U.S. patent application number 15/766509 was filed with the patent office on 2018-10-11 for nano suspension lubricants.
The applicant listed for this patent is Hindustan Petroleum Corporation Limited. Invention is credited to Sri Ganesh Gandham, Amitabh Kumar Jain, Annaji Rajiv Kumar Tompala, Venkateswarlu Choudary Nettem, Venkata Chalapathi Rao Peddy, Srinivas Vadapalli.
Application Number | 20180291305 15/766509 |
Document ID | / |
Family ID | 56801666 |
Filed Date | 2018-10-11 |
United States Patent
Application |
20180291305 |
Kind Code |
A1 |
Kumar Tompala; Annaji Rajiv ;
et al. |
October 11, 2018 |
Nano Suspension Lubricants
Abstract
A method for preparing a nano suspension lubricant comprises
providing substantially spherical nano particles of size ranging
from about less than 50 nanometers to about 100 nanometers. The
method further comprises mixing the nano particles and a surfactant
in about 1:1 ratio in a solvent to form a mixture. The solvent is
evaporated from the mixture to obtain surface modified nano
particles. The surface modified nano particles include the nano
particles coated with the surfactant. The method comprises mixing
the surface modified nano particles with a lubricating fluid to
form the nano suspension lubricant, where the lubricating fluid
comprises about 90% to 99% base oil and about 1% to 10%
additives.
Inventors: |
Kumar Tompala; Annaji Rajiv;
(Bengluru, IN) ; Vadapalli; Srinivas;
(Visakhapatnam, IN) ; Jain; Amitabh Kumar; (Navi
Mumbai, IN) ; Peddy; Venkata Chalapathi Rao;
(Bengluru, IN) ; Nettem; Venkateswarlu Choudary;
(Bengluru, IN) ; Gandham; Sri Ganesh;
(Visakhapatnam, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hindustan Petroleum Corporation Limited |
Mumbai |
|
IN |
|
|
Family ID: |
56801666 |
Appl. No.: |
15/766509 |
Filed: |
June 30, 2016 |
PCT Filed: |
June 30, 2016 |
PCT NO: |
PCT/IN2016/050208 |
371 Date: |
April 6, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10N 2030/06 20130101;
C10N 2030/10 20130101; C10N 2020/06 20130101; C10N 2070/00
20130101; C10M 171/06 20130101; C10M 2203/1006 20130101; C10M
2207/289 20130101; C10M 2215/04 20130101; C10M 2201/065 20130101;
C10M 177/00 20130101; C10M 2201/066 20130101; C10M 101/02 20130101;
C10M 2203/022 20130101; C10M 2207/126 20130101; C10N 2020/061
20200501; C10M 157/10 20130101; C10N 2030/54 20200501; C10M 2201/05
20130101; C10N 2030/12 20130101; C10M 2203/06 20130101; C10N
2040/25 20130101 |
International
Class: |
C10M 171/06 20060101
C10M171/06; C10M 177/00 20060101 C10M177/00; C10M 101/02 20060101
C10M101/02 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 6, 2015 |
IN |
3793/MUM/2015 |
Claims
1. A method for preparing a nano suspension lubricant, the method
comprising: providing substantially spherical nano particles of
size ranging from about less than 50 nanometers to about 100
nanometers; mixing the nano particles and a surfactant in about 1:1
ratio in a solvent to form a mixture; evaporating the solvent from
the mixture to obtain surface modified nano particles, wherein the
surface modified nano particles include the nano particles coated
with the surfactant; and mixing the surface modified nano particles
with a lubricating fluid to form the nano suspension lubricant,
wherein the lubricating fluid comprises about 90% to 99% base oil
and about 1% to 10% additives.
2. The method as claimed in claim 1, wherein the mixing the surface
modified nano particles with the lubricating fluid includes
sonicating the surface modified nano particles in the lubricating
fluid in an ultra-sound sonicator at an amplitude of about 50% and
a power of about 200 watts.
3. The method as claimed in claim 2, wherein the sonicating the
surface modified nano particles in the lubricating fluid takes
place for about 60 minutes, wherein the sonicating is performed in
pulse mode with 0.5 second pulse for about 30 minutes and the
sonicating is performed in continuous mode for remaining 30
minutes.
4. The method as claimed in claim 1, wherein the mixing the nano
particles and the surfactant in the solvent includes stirring the
nano particles and the surfactant in the solvent in an ultra-sound
sonicator for about 7 to 8 hours.
5. The method as claimed in claim 1, wherein the evaporating the
solvent from the mixture includes allowing the solvent to evaporate
from the mixture at room temperature.
6. The method as claimed in claim 1, wherein the solvent is one of
n-hexane, iso octane and toluene.
7. The method as claimed in claim 1, wherein the nano particles are
selected from one of copper, molybdenum disulphide, and tungsten
disulphide.
8. The method as claimed in claim 1, wherein the surfactant is
selected from one of lauric acid, sorbitan monooleate, and
cetrimonium bromide based on the electronegativity of the
surfactant.
9. The method as claimed in claim 1, wherein the base oil is
selected from one of petroleum fractions, mineral oils, crude oils,
and a combination thereof.
10. The method as claimed in claim 1, wherein the additives in the
lubricating fluid are selected from one of antioxidants,
detergents, anti-foaming agents, anti-friction agents, anti-wear
agents, and a combination thereof.
11. A nano suspension lubricant comprising: a lubricating fluid
comprising of about 90% to 99% base oil and about 1% to 10%
additives; and surface modified copper nano particles from about
0.05 weight % to 0.1 weight % dispersed in the lubricating fluid,
wherein the surface modified copper nano particles include copper
nano particles coated with lauric acid surfactant, wherein the
copper nano particles have a size less than about 50
nanometers.
12. A nano suspension lubricant comprising: a lubricating fluid
comprising of about 90% to 99% base oil and about 1% to 10%
additives; and surface modified molybdenum disulphide nano
particles from about 0.05 weight % to 0.1 weight % dispersed in the
lubricating fluid, wherein the surface modified molybdenum
disulphide nano particles include molybdenum disulphide nano
particles coated with Sorbitan Monooleate surfactant, wherein the
molybdenum disulphide nano particles have a size less than about
100 nanometers.
13. A nano suspension lubricant comprising: a lubricating fluid
comprising of about 90% to 99% base oil and about 1% to 10%
additives; and surface modified tungsten disulphide nano particles
from about 0.05 weight % to 0.1 weight % dispersed in the
lubricating fluid, wherein the surface modified tungsten disulphide
nano particles include tungsten disulphide nano particles coated
with Cetrimonium Bromide surfactant, wherein the tungsten
disulphide nano particles have a size less than about 100
nanometers.
Description
TECHNICAL FIELD
[0001] The present subject matter relates, in general, to
lubricants and, in particular, to nano suspension lubricants.
BACKGROUND
[0002] Lubricants play an important role in improving machine life
and performance characteristics of a machine. Lubricants are
generally used in mechanical components of machines and automobiles
to reduce friction and wear. Friction and wear between moving
mechanical components of machines and automobiles often result in
energy and material losses. Thus, lubricants are used to improve
energy efficiency and mechanical durability of the moving
mechanical components.
[0003] In general, the functions of a lubricant are to: (a) keep
surfaces of moving components separated under all loads,
temperatures and speeds, thus minimizing friction and wear; (b) act
as a cooling fluid removing the heat produced by friction or from
external sources; (c) remain adequately stable in order to ensure
uniform behavior over the forecasted useful life; and (d) protect
surfaces of the moving mechanical components from the attack of
corrosive products formed during operation.
[0004] In order to meet the various requirements, one or more types
of additives or property modifiers are added into a base oil in a
lubricant composition. These additives can be, for example,
antioxidants, detergents, anti-wear substances, metal deactivators,
corrosion inhibitors, rust inhibitors, etc.
BRIEF DESCRIPTION OF DRAWINGS
[0005] The detailed description is described with reference to the
accompanying figures. In the figures, the left-most digit(s) of a
reference number identifies the figure in which the reference
number first appears. The same numbers are used throughout the
drawings to reference like features and components. For simplicity
and clarity of illustration, elements in the figures are not
necessarily to scale.
[0006] FIG. 1 illustrates a method for preparing a nano suspension
lubricant, according to an example implementation.
[0007] FIG. 2 graphically illustrates X-ray Diffraction analysis
test results for a copper based nano suspension lubricant,
according to an example implementation.
[0008] FIG. 3(a) illustrates wear test results for a Molybdenum
Disulphide (MoS.sub.2) based nano suspension lubricant with diesel
engine oil as the lubricating fluid at a load of 40 kgf, according
to an example implementation.
[0009] FIG. 3(b) illustrates wear test results for a Molybdenum
Disulphide (MoS.sub.2) based nano suspension lubricant with diesel
engine oil as the lubricating fluid at a load of 60 kgf, according
to an example implementation.
[0010] FIG. 3(c) illustrates wear test results for a Molybdenum
Disulphide (MoS.sub.2) based nano suspension lubricant with petrol
engine oil as the lubricating fluid at a load of 40 kgf, according
to an example implementation.
[0011] FIG. 3(d) illustrates wear test results for a Molybdenum
Disulphide (MoS.sub.2) based nano suspension lubricant with petrol
engine oil as the lubricating fluid at a load of 60 kgf, according
to an example implementation.
[0012] FIG. 3(e) illustrates wear test results for a Molybdenum
Disulphide (MoS.sub.2) based nano suspension lubricant with gear
oil of viscosity grade SAE 80 W 90 as the lubricating fluid at a
load of 40 kgf, according to an example implementation.
[0013] FIG. 3(f) illustrates wear test results for a Molybdenum
Disulphide (MoS.sub.2) based nano suspension lubricant with gear
oil of viscosity grade SAE 80 W 90 as the lubricating fluid at a
load of 80 kgf, according to an example implementation.
[0014] FIG. 3(g) illustrates wear test results for a Molybdenum
Disulphide (MoS.sub.2) based nano suspension lubricant with gear
oil of viscosity grade EP 140 as the lubricating fluid at a load of
40 kgf, according to an example implementation.
[0015] FIG. 3(h) illustrates wear test results for a Molybdenum
Disulphide (MoS.sub.2) based nano suspension lubricant with gear
oil of viscosity grade EP 140 as the lubricating fluid at a load of
80 kgf, according to an example implementation.
[0016] FIG. 4(a) graphically illustrates friction test results
indicating the variation in coefficient of friction for the
MoS.sub.2 based nano suspension lubricant with diesel engine oil as
the lubricating fluid, according to an example implementation.
[0017] FIG. 4(b) graphically illustrates friction test results
indicating the variation in seizure load for the MoS.sub.2 based
nano suspension lubricant with diesel engine oil as the lubricating
fluid, according to an example implementation.
[0018] FIG. 4(c) graphically illustrates friction test results
indicating the variation in coefficient of friction for the
MoS.sub.2 based nano suspension lubricant with petrol engine oil as
the lubricating fluid, according to an example implementation.
[0019] FIG. 4(d) graphically illustrates friction test results
indicating the variation in seizure load for the MoS.sub.2 based
nano suspension lubricant with petrol engine oil as the lubricating
fluid, according to an example implementation.
[0020] FIG. 4(e) graphically illustrates friction test results
indicating the variation in coefficient of friction for the
MoS.sub.2 based nano suspension lubricant with gear oil of
viscosity grade SAE 80 W 90 as the lubricating fluid, according to
an example implementation.
[0021] FIG. 4(f) graphically illustrates friction test results
indicating the variation in seizure load for the MoS.sub.2 based
nano suspension lubricant with gear oil of viscosity grade SAE 80 W
90 as the lubricating fluid, according to an example
implementation.
[0022] FIG. 4(g) graphically illustrates friction test results
indicating the variation in coefficient of friction for the
MoS.sub.2 based nano suspension lubricant with gear oil of grade EP
140 as the lubricating fluid, according to an example
implementation.
[0023] FIG. 4(h) graphically illustrates friction test results
indicating the variation in seizure load for the MoS.sub.2 based
nano suspension lubricant with gear oil of viscosity grade EP 140
as the lubricating fluid, according to an example
implementation.
[0024] FIG. 5(a) graphically illustrates extreme pressure (EP) test
results indicating the variation in Load wear index (LWI) of the
MoS.sub.2 based nano suspension lubricant with gear oil of
viscosity grade SAE 80 W 90 as the lubricating fluid, according to
an example implementation.
[0025] FIG. 5(b) graphically illustrates the extreme pressure (EP)
test results indicating the variation in weld load of the MoS.sub.2
based nano suspension lubricant with gear oil of viscosity grade
SAE 80 W 90 as the lubricating fluid, according to an example
implementation.
[0026] FIG. 5(c) graphically illustrates the extreme pressure (EP)
test results indicating the variation in Load wear index (LWI) of
the MoS.sub.2 based nano suspension lubricant with gear oil of
viscosity grade EP 140 as the lubricating fluid, according to an
example implementation.
[0027] FIG. 5(d) graphically illustrates the extreme pressure (EP)
test results indicating the variation in weld load of the MoS.sub.2
based nano suspension lubricant with gear oil of viscosity grade EP
140 as the lubricating fluid, according to an example
implementation.
[0028] FIG. 6 graphically illustrates characterization of worn out
balls on a scanning electron microscope with X-ray diffraction
attachment for the MoS.sub.2 based nano suspension lubricant,
according to an example implementation.
[0029] FIG. 7 graphically illustrates variations in brake thermal
efficiency of the MoS.sub.2 based nano suspension lubricant in a
petrol engine test rig, according to an example implementation.
[0030] FIG. 8 graphically illustrates variations in brake thermal
efficiency of the MoS.sub.2 based nano suspension lubricant in a
diesel engine test rig, according to an example implementation.
[0031] FIG. 9 graphically illustrates variation in total fuel
consumption for the MoS.sub.2 based nano suspension lubricant,
according to an example implementation.
[0032] FIG. 10(a) illustrates wear test results for a Tungsten
Disulphide (WS.sub.2) based nano suspension lubricant with diesel
engine oil as the lubricating fluid at a load of 40 kgf, according
to an example implementation.
[0033] FIG. 10(b) illustrates wear test results for the Tungsten
Disulphide (WS.sub.2) based nano suspension lubricant with diesel
engine oil as the lubricating fluid at a load of 60 kgf, according
to an example implementation.
[0034] FIG. 10(c) illustrates wear test results for the Tungsten
Disulphide (WS.sub.2) based nano suspension lubricant with petrol
engine oil as the lubricating fluid at a load of 40 kgf, according
to an example implementation.
[0035] FIG. 10(d) illustrates wear test results for the Tungsten
Disulphide (WS.sub.2) based nano suspension lubricant with petrol
engine oil as the lubricating fluid at a load of 60 kgf, according
to an example implementation.
[0036] FIG. 10(e) illustrates wear test results for the Tungsten
Disulphide (WS.sub.2) based nano suspension lubricant with gear oil
of viscosity grade SAE 80 W 90 as the lubricating fluid at a load
of 40 kgf, according to an example implementation.
[0037] FIG. 10(f) illustrates wear test results for the Tungsten
Disulphide (WS.sub.2) based nano suspension lubricant with gear oil
of viscosity grade SAE 80 W 90 as the lubricating fluid at a load
of 80 kgf, according to an example implementation.
[0038] FIG. 10(g) illustrates wear test results for the Tungsten
Disulphide (WS.sub.2) based nano suspension lubricant with gear oil
of grade EP 140 as the lubricating fluid at a load of 40 kgf,
according to an example implementation.
[0039] FIG. 10(h) illustrates wear test results for the Tungsten
Disulphide (WS.sub.2) based nano suspension lubricant with gear oil
of viscosity grade EP 140 as the lubricating fluid at a load of 80
kgf, according to an example implementation.
[0040] FIG. 11(a) graphically illustrates friction test results
indicating the variation in coefficient of friction for the
WS.sub.2 based nano suspension lubricant with diesel engine oil as
the lubricating fluid, according to an example implementation.
[0041] FIG. 11(b) graphically illustrates friction test results
indicating the variation in seizure load for the WS.sub.2 based
nano suspension lubricant with diesel engine oil as the lubricating
fluid, according to an example implementation.
[0042] FIG. 11(c) graphically illustrates friction test results
indicating the variation in coefficient of friction for the
WS.sub.2 based nano suspension lubricant with petrol engine oil as
the lubricating fluid, according to an example implementation.
[0043] FIG. 11(d) graphically illustrates friction test results
indicating the variation in seizure load for the WS.sub.2 based
nano suspension lubricant with petrol engine oil as the lubricating
fluid, according to an example implementation.
[0044] FIG. 11(e) graphically illustrates friction test results
indicating the variation in coefficient of friction for the
WS.sub.2 based nano suspension lubricant with gear oil of viscosity
grade SAE 80 W 90 as the lubricating fluid, according to an example
implementation.
[0045] FIG. 11(f) graphically illustrates friction test results
indicating the variation in seizure load for the WS.sub.2 based
nano suspension lubricant with gear oil of viscosity grade SAE 80 W
90 as the lubricating fluid, according to an example
implementation.
[0046] FIG. 11(g) graphically illustrates friction test results
indicating the variation in coefficient of friction for the
WS.sub.2 based nano suspension lubricant with gear oil of viscosity
grade EP 140 as the lubricating fluid, according to an example
implementation.
[0047] FIG. 11(h) graphically illustrates friction test results
indicating the variation in seizure load for the WS.sub.2 based
nano suspension lubricant with gear oil of viscosity grade EP 140
as the lubricating fluid, according to an example
implementation.
[0048] FIG. 12 graphically illustrates characterization of worn out
balls on a scanning electron microscope with X-ray diffraction
attachment for the WS.sub.2 based nano suspension lubricant,
according to an example implementation.
[0049] FIG. 13 graphically illustrates variations in brake thermal
efficiency of the WS.sub.2 based nano suspension lubricant in the
petrol engine rig, according to an example implementation.
[0050] FIG. 14 graphically illustrates variations in brake thermal
efficiency of the WS.sub.2 based nano suspension lubricant in the
diesel engine rig, according to an example implementation.
[0051] FIG. 15 graphically illustrates the variation in total fuel
consumption for the WS.sub.2 based nano suspension lubricant,
according to an example implementation.
[0052] FIG. 16(a) graphically illustrates extreme pressure (EP)
test results indicating the variation in Load wear index (LWI) of
the WS.sub.2 based nano suspension lubricant with gear oil of
viscosity grade SAE 80 W 90 as the lubricating fluid, according to
an example implementation.
[0053] FIG. 16(b) graphically illustrates the extreme pressure (EP)
test results indicating the variation in weld load of the WS.sub.2
based nano suspension lubricant with gear oil of viscosity grade
SAE 80 W 90 as the lubricating fluid, according to an example
implementation.
[0054] FIG. 16(c) graphically illustrates the extreme pressure (EP)
test results indicating the variation in Load wear index (LWI) of
the WS.sub.2 based nano suspension lubricant with gear oil of
viscosity grade EP 140 as the lubricating fluid, according to an
example implementation.
[0055] FIG. 16(d) graphically illustrates the extreme pressure (EP)
test results indicating the variation in weld load of the WS.sub.2
based nano suspension lubricant with gear oil of viscosity grade EP
140 as the lubricating fluid, according to an example
implementation.
DETAILED DESCRIPTION
[0056] Typically, lubricants are prepared by adding additives to a
base oil. Generally, on fractional distillation of crude oil,
different base oils separate out as distillates. Examples of base
oils are petroleum distillates, mineral oils, vegetable oils,
esters, polyolefin, etc. Recently, nano particles have been tested
for use as additives in the base oils for lubricants in automobile
and other industrial applications. The nano particles may be
metals, non-metals, or salts of metals and non-metals having an
average particle diameter up to 100 nanometers. Nano particle based
lubricants exhibit better tribological properties as compared to
ordinary lubricants without nanoparticles. Nanoparticles are
considered well suited for tribological applications since
lubrication takes place at nano scale level. For instance, certain
nano particle molecules can form a thin coating with the thickness
of just one or two molecules to separate surface asperities of the
moving components of a machine. This may result in better friction
resistance between the moving components.
[0057] Nano particles have a high surface affinity and chemical
reactivity and their small sizes enable them to penetrate into wear
crevices. Thus, nano particles are emerging as suitable additives
for industrial lubricants, such as, lubricating engine oils,
greases, dry film lubricants, and forging lubricants. Several types
of nanoparticles have been studied as potential additives for
lubricants, including metal oxides of silicon, titanium, nickel,
tin, aluminium, and zinc; fluorides of metals such as cerium,
lanthanum, and calcium; and zinc, tin, and lead sulfides, and
metals, such as nickel, zinc, tin, and silver, and non-metals like
carbon nanotubes.
[0058] It is generally postulated that rigid spherical and
cylindrical nanoparticles dispersed in the base oils protect
contacting metal surfaces that are in relative motion from wear by
rolling actions, i.e., the nano particles act as miniature ball
bearings. However, at higher loads and speeds, the nano particles
fall short in the intended lubricating functions. In particular,
high wear rates and friction failures remain to be challenging
issues for nano particle based lubricants. Thus, nano particles
dispersed in base oils are not able to sufficiently provide the
intended functions of the nano particle based lubricant.
[0059] Better lubricating properties may be obtained when the nano
particles are dispersed in lubricating fluids, such as fully
formulated lubricants, for example, petrol engine oil of SM grade,
diesel engine oil of CI 4 grade, and gear oil GL 4 grade. The
lubricating fluids include base oils and other additives, such as,
detergents, anti-foaming agents, antioxidants, etc., that have
different property modifying effects which make them suitable for
use as lubricants. However, there lies a crucial challenge with
dispersing the nano particles in the lubricating fluid. On mixing
the nano particles in the lubricating fluid, the nano particles
have a tendency to agglomerate and settle down after a certain
period of time. This results in an unstable solution of the nano
particles in the lubricating fluid. Additionally, it is a challenge
to obtain a uniform dispersion of the nano particles in the
lubricating fluid.
[0060] The subject matter described herein relates to a method for
preparing a nano suspension lubricant. The nano suspension
lubricant described herein includes nano particles dispersed in the
lubricating fluid. The lubricating fluid includes a base oil, such
as, mineral oils, vegetable oils, esters, etc., and other
additives, such as, boron, calcium, etc., that act as antioxidants,
anti-wear agents, and the like. In an example implementation, the
lubricating fluid may be a fully formulated lubricant, such as,
petrol engine oil of SM grade, diesel engine oil CI 4 grade, and
gear oil GL 4 grade. The nano suspension lubricant is prepared by
mixing surface modified nano particles in the lubricating fluid. As
explained later based on test results, the nano suspension
lubricant has a greater stability in the lubricating fluid. In an
example implementation, surface modification of the nano particles
results in the nano particles being coated with an appropriate
surfactant selected based on the electrostatic charge of the nano
particle and the surfactant that coats on the nano particle. The
surface modified nano particles are mixed in the lubricating fluid
to form the nano suspension lubricant. The surfactant coated on the
surface of the nano particles prevents agglomeration of the nano
particles in the lubricating fluid and ensures formation of a
stable suspension of the surface modified nano particles in the
lubricating fluid. In addition, the nano suspension lubricant
obtained on mixing the surface modified nano particles in the
lubricating fluid also has better tribological properties, such as,
better friction resistance, wear resistance, and an improved brake
thermal efficiency, as compared to a conventional nano particle
lubricant in which the nano particles are dissolved in a base
oil.
[0061] Further, tests reveal that there is no deterioration of the
physico-chemical properties, such as viscosity index, total acid
number, total base number, etc. of the nano suspension lubricant
and hence the nano suspension lubricant is suitable for use in the
automobile environment.
[0062] These and other advantages of the present subject matter
would be described in greater detail in conjunction with the
following figures. It should be noted that the description and
figures merely illustrate the principles of the present subject
matter and in no way limit the present subject matter to the
description and figures illustrated herein.
[0063] FIG. 1 illustrates a method 100 for preparing the nano
suspension lubricant, according to an example implementation of the
present subject matter. The method 100 for preparing the nano
suspension lubricant includes providing substantially spherical
nano particles, at block 102. The nano particles may have different
structures. For instance, metallic nano particles, such as zinc,
tin, copper, tungsten, etc., generally have a substantially
spherical structure, while non-metallic nano particles like,
tungsten disulphide nano rods and carbon nano tubes have a
cylindrical structure with diameters in the nanometric range. The
present method includes providing substantially spherical nano
particles having an average particle diameter ranging from about
less than 50 nanometers to about 100 nanometers. It has been tested
that the substantially spherical nano particles over the mentioned
range exhibit optimal lubricating properties. Nano particles having
a greater particle diameter may tend to wear out the surfaces of
the moving mechanical components that are lubricated using the nano
suspension lubricant. In an example implementation, the nano
particles used for the method 100 may be selected from one of
copper, molybdenum disulphide, and tungsten disulphide.
[0064] At block 104, the method 100 includes mixing the nano
particles and a surfactant in about 1:1 ratio in a solvent to form
a mixture. In an example implementation, the solvent may be one of
n-hexane, iso octane and toluene. In an example implementation, the
solution is stirred in a probe sonicator for about 1 hour for
thorough mixing. For stability in a fluid medium, the surface of
the nano particles needs to be suitably modified with the
surfactant. The surfactants include compounds that lower the
surface tension between two liquids or a liquid and a solid and may
be used as detergents, anti-foaming agents, and dispersants. Common
examples of surfactants include oleic acid, palmitic acid, lauryl
alcohol, etc. When the surfactants are mixed with the Nano
particles, one end of the surfactant molecule attach to the surface
of the nano particle through chemical bonds. The other end of the
surfactant molecule is free and extends into the lubricating fluid.
Thus, the surfactants generate an effective repulsive force between
the nano particles due to steric repulsion between the surfactant
molecules attached to the surface of the nano particles. The
effective repulsive force between the nano particles coated with
the surfactant results in a stable mixture of the nano particles in
the lubricating fluid. According to an example implementation, the
surfactant may be selected from one of lauric acid, and cetrimonium
bromide based on the electronegativity of the surfactant and the
type of nano particle on which it is to be coated. In an example
implementation, the nano particles and the surfactant are mixed in
the solvent by stirring the nano particles and the surfactant in
the solvent in an ultra-sound sonicator for about 7 to 8 hours.
[0065] At block 106, the method 100 includes evaporating the
solvent from the mixture to obtain surface modified nano particles.
In an example implementation, the solvent may evaporated at room
temperature. On evaporation of the solvent, one end of the
surfactant molecule properly bonds to the surface of the nano
particles. The surface modified nano particles include the nano
particles coated with the surfactant. The surfactant ensures that
the surface modified nano particles do not agglomerate when mixed
in the lubricating fluid. Thus, a stable dispersion of the surface
modified nano particles in the lubricating fluid may be
obtained.
[0066] At block 108, the method 100 includes mixing the surface
modified nano particles with the lubricating fluid. The lubricating
fluid includes base oil and additives. In an example
implementation, the lubricating fluid includes about 90% to 99%
base oil and about 1% to 10% additives. The additives present in
the lubricating fluid may include corrosion inhibitors often used
in engine coolant like Boron, alkaline or detergent additives, such
as magnesium and calcium used to neutralize acids which form during
a combustion process in an engine, a friction-reducer and
anti-oxidant, such as molybdenum, an anti-foaming agent, such as
silicon, and an anti-oxidant and anti-wear agent, such as Zinc
dialkyl dithio phosphate (ZDDP). The lubricating fluid contains the
above mentioned elements as additives for functioning under severe
conditions. In an example implementation, mixing the surface
modified nano particles with the lubricating fluid may include
sonicating the surface modified nano particles in the lubricating
fluid. The sonication may be performed in an ultra-sound sonicator
at an amplitude of about 50% and a power of about 200 watts for a
duration of about 60 minutes. To obtain optimal results, in an
example implementation, the sonication of the surface modified nano
particles in the lubricating fluid may be performed in two
different modes of sonication. In the example implementation, for
30 minutes the sonication may be performed in pulse mode with 0.5
second pulse. This prevents the agglomeration of the surface
modified nano particles. For remaining 30 minutes the sonication is
performed in continuous mode which uniformly disperses the surface
modified nano particles into the lubricating fluid.
[0067] The following discussion is directed to various examples of
the present subject matter. Although certain methods and
compositions have been described herein as examples, the scope of
coverage of this patent application is not limited thereto. On the
contrary, the present subject matter covers all methods and
compositions fairly falling within the scope of the claims either
literally or under the doctrine of equivalents.
[0068] Certain terms are used throughout the description to refer
to certain components and are to be construed as being mentioned by
way of example and for purposes of explanation and not as
limiting.
[0069] The term "viscosity index" as used in the examples refers to
change in viscosity of a lubricant with change in temperature. The
lower the viscosity index, the greater is the change of viscosity
of a lubricant with temperature. Thus, the higher the viscosity
index, the better is the quality of the lubricant. A viscosity
index value greater than 90 is preferred for the lubricant.
[0070] The term "American Society for Testing and Materials (ASTM)
D 445" as used in the examples refers to a test method that
specifies a procedure for determination of kinematic viscosity of
the lubricant by measuring the time for a volume of liquid to flow
under gravity through a calibrated glass capillary viscometer.
[0071] The term "total acid number" (TAN) ASTM D 664 as used in the
examples refer to a measure of weak organic and strong inorganic
acids present in a lubricant. The TAN is the amount of potassium
hydroxide in milligrams required to neutralize the acids in one
gram of the lubricant. The TAN value indicates potential
corrosiveness of the lubricant. A TAN value lesser than 3 indicates
that the lubricant is stable.
[0072] The term "total base number" (TBN) as used in the examples
refers to effectiveness of the lubricant in controlling acid
formation during combustion process. The higher the TBN, the more
effective the lubricant is in suspending wear-causing contaminants
and reducing the corrosive effects of acids over an extended period
of time. A TBN value higher than 9 indicates that the lubricant has
good control over acid formation during the combustion process.
[0073] The term "ASTM D 2896" as used in the examples refers to a
test method for determination of the TBN of the lubricant by
potentiometric titration with perchloric acid in glacial acetic
acid.
[0074] The term "ASTM copper strip corrosion standard as per ASTM D
130" as used in the examples refers to a standard used for
representing corrosion protection of the lubricant. The standard
has classification numbers from 1 to 4 for various color and
tarnish levels of a copper strip immersed in the lubricant. A
classification number of 1a indicates excellent corrosion
protection, 1b indicates good corrosion protection, and 1c
indicates sufficient corrosion protection of the lubricant.
[0075] The term "copper strip corrosion test" as used in the
examples refers to a test used for determining the classification
number of the lubricant. The test involves immersion of a polished
copper strip in the lubricant at elevated temperature for a period
of time and testing the color and tarnish levels of the copper
strip.
[0076] The term "four-ball wear test machine" as used in the
examples refers to a machine used for testing various performance
characteristics of the lubricant. The machine comprises of a ball
pot in which three balls are clamped together and thereby kept
stationary or fixed in one position. These balls are then covered
with the lubricant. A fourth ball is pressed against a cavity
formed by the three stationary balls and the fourth ball is
rotated.
[0077] The term "wear scar diameter" as used in the examples refers
to diameter of wear scars on the three stationary balls tested on
the four-ball wear test machine. The larger the wear scar, the
poorer is the lubricating ability of the lubricant.
[0078] The term "ASTM D 4172" as used in the examples refers to a
test method for evaluation of the anti-wear properties of the
lubricants in sliding contact by means of the Four-Ball Wear Test
Machine.
[0079] The term "seizure load" as used in the examples refers to a
load at which a sudden increase in coefficient of friction value
occurs. The higher the seizure load, the better the anti-friction
property of the lubricant.
[0080] The term "ASTM D 5183" as used in the examples refers to a
test method for determining coefficient of friction of the
lubricant by means of the Four-Ball Wear Test Machine. Initially, a
load is applied which gradually increased at regular time intervals
until the lubricant undergoes seizure.
[0081] The term "friction test" as used in the examples refers to a
test performed for determining the seizure load and the coefficient
of friction of the lubricant. The seizure load refers to the load
at which there is a sharp rise in fractional torque characterized
on a graph while the machine is running. The coefficient of
friction is determined by considering the loads between initial
load and the seizure load.
[0082] The term "ASTM D 2783" as used in the examples refers to a
test method for determination of the load-carrying properties of
lubricating fluids. The following two determinations are made using
ASTM D 2783: 1. Load-wear index, and 2. Weld load by means of the
four-ball extreme-pressure tester.
[0083] The term "load-wear index" as used in the examples refers to
an extreme pressure (EP) property of the lubricant calculated using
the four-ball wear test machine Here the speed of rotation is
maintained at 1760 RPM and the whole test procedure is done under
room temperature. A series of tests of 10-s duration are carried
out with increasing loads during each tests until 4 balls weld
under extreme pressure. The load at which weld occurs is called the
weld load. The first run is made at an initial load of 40 kgf and
the additional runs are carried out at consecutively higher loads
until and the 4 balls weld under extreme pressure. A total of 10
readings are considered in the test and the corrected load is
calculated for all ten readings. The load wear index is calculated
from the corrected load. The corrected load is calculated as
follows:
Corrected load=LDh/X;
where L is the applied load in kgf, Dh is hertz scar diameter in
mm, and X is average scar diameter in mm. Hertz scar diameter is
the average diameter, in mm, of an indentation caused by
deformation of the balls under static load before application of
the load. It may be calculated from the equation Dh=8.73.times.10-3
(P).sup.1/3.
[0084] The term "endurance test" as used in the examples refers to
a test conducted on an engine by subjecting it to varying loads and
varying speeds for a continuous period of 80 hours without
stoppage. This is used to determine the engine wear & tear and
fuel consumption over a period of time.
[0085] The term "bench test" as used in the examples refers to a
test performed on the engine at a particular load and a particular
speed to determine the efficiency of the engine at that particular
load and speed.
[0086] The term "petrol engine rig" as used in the examples refers
to a test rig consisting of petrol engine connected to a
dynamometer for applying speed and loads to an engine.
[0087] The term "diesel engine rig" as used in the examples refers
to test rig consisting of diesel engine connected to dynamometer
for applying speed and loads to an engine.
EXAMPLES
[0088] The following general compositions of nano suspension
lubricants, are used in the Examples.
Example 1
Copper Based Nano Suspension Lubricant
[0089] In an example implementation, the nano suspension lubricant
includes surface modified copper nano particles. The copper nano
particles have a particle diameter of less than about 50
nanometers. At this range the copper nano particles used in the
nano suspension lubricant gives optimal results. A surface of the
copper nano particles is modified using a surfactant to prevent
agglomeration of the copper nano particles and to get a uniform
dispersion of the copper nano particles in the lubricating fluid.
Generally, carboxylate groups attach themselves to metal and metal
oxide nano particles making them stable in fluids. The carboxylate
groups are soluble in both water as well as oils as they contain
both lipophilic and hydrophilic ends. Some of the carboxylate
groups mostly used for oil dispersion are lauric acid, stearic
acid, and maleic acid. In an example implementation, lauric acid is
selected as a surfactant for surface modification of the copper
nano particles. The copper nano particles are coated with the
lauric acid surfactant to form the surface modified copper nano
particles. As a result of the surface modification, the polar head
of the lauric acid surfactant attaches to the copper nano particles
and the hydrophobic end of the lauric acid surfactant attaches to
the oil molecule enabling a stable dispersion of the surface
modified copper nano particles in the lubricating fluid. In the
example implementation, the surface modified copper nano particles
from about 0.05 weight % to 0.1 weight % is dispersed in the
lubricating fluid. Mixing the surface modified copper nano
particles at the mentioned range gives optimal results for the nano
suspension lubricant. Beyond the above mentioned range of weight %
of the surface modified nano particles there may be an increase in
wear effects on mechanical moving components of an engine where the
nano suspension lubricant is being used. This may be due to
overcrowding of the surface modified copper nano particles at an
interface between the mechanical moving components of the engine in
relative motion. In the example implementation, the lauric acid
surfactant is mixed in approximately 25.0 ml of n-hexane or toluene
solvent by proper stirring to form a mixture. In an example
implementation, lauryl alcohol and triton-X may also be used as
surfactants. The copper nano particles are added to the mixture and
stirred again for 7-8 hours. The n-hexane or toluene solvent is
evaporated at room temperature by keeping the mixture undisturbed
overnight thus leaving behind the surface modified copper nano
particles. The surface modified copper nano particles are coated
with the lauric acid surfactant. The surface modified copper nano
particles are mixed in the lubricating fluid using an ultra-sound
sonicator for 1 hour to achieve a stable suspension of the surface
modified copper nano particles in the lubricating fluid.
[0090] In an example implementation, the amount of the copper nano
particles and surfactant to be mixed in the lubricating fluid to
form the stable suspension of the surface modified copper nano
particles in the lubricating fluid is given in the following
table.
TABLE-US-00001 TABLE 1.1 Amount of the copper nano particles and
surfactants used to obtain a stable nano suspension lubricant
according to an example implementation Amount of surfactant Mass of
nano to be mixed with Mass fraction particles to be nano particles
of nano dispersed in of and solvent for Surfactant particles
lubricant surface modification Lauric acid 0.05% 0.45 gm 0.4 gm
0.1% 0.9 gm 0.8 gm Lauryl alcohol 0.05% 0.45 gm 12 ml 0.1% 0.9 gm
20 ml Triton X-100 0.05% 0.45 gm 12 ml 0.1% 0.9 gm 24 ml
[0091] To test the stability of the copper nano suspension
lubricant, an accelerated stability test on a high speed centrifuge
has been conducted. In a centrifuge due to the centrifugal action
the lighter object move to the top and heavier objects move to the
bottom. Different suspensions of nano lubricants made of bare and
surface modified nano particles are tested on a centrifuge for
accelerated agglomeration of the nano particles under centrifugal
action. The centrifugal force applied in the centrifuge tends to
bring the nano particles together and agglomerates them. Thus, an
uniformly dispersed solvent would remain stable for a longer period
of time in the centrifuge.
[0092] The following conditions are employed in the test [0093]
Duration of the test 20 mins [0094] Speed of the centrifuge 10,000
RPM
[0095] The test results indicate that when uncoated nano particles
are dispersed in the lubricating fluid, the nano particles get
agglomerated and settle within the first minute of the test. In an
example implementation, the nano suspension lubricant containing 2
mMol of lauryl alcohol as surfactant remains stable for about 10
minutes and the nano suspension lubricant containing 2.5 mMol of
lauryl alcohol remains stable for about 20 minutes under the
centrifugal action.
[0096] Further, tests are also being performed for evaluating
changes in Physico-chemical properties, such as, density, viscosity
index, total acid number, total base number, sulfonated ash, flash
Point, fire point, pour point, etc., of the nano suspension
lubricant dispersed with surface modified copper nano particles
according to an example implementation of the present subject
matter. Any deterioration of the Physico-chemical properties of the
nano suspension lubricant below predetermined standards may render
the nano suspension lubricant unsuitable for use in automotive
environment. The Table 1.2 depicts test results of the
physico-chemical properties of the copper based nano suspension
lubricant.
TABLE-US-00002 TABLE 1.2 Test results of the physico chemical
properties of the copper based nano suspension lubricant Base
lubricant + Base lubricant + SR. TEST Base 0.05% nano 0.1% nano NO.
PROPERTIES METHOD lubricant copper copper 1 DENITY @ 15 DEG C. g/ml
ASTM D 1298 0.8897 0.8899 0.8912 2 Kinematic Viscosity at 40 deg
C., m ASTM D 445 138.8 135.7 141 cst 3 Kinematic Viscosity at 100
deg C., ASTM D 445 15.68 15.33 15.84 cst 4 TBN mgKOH/gm ASTN D 2896
10.4 9.84 10.3 5 TAN mgKOH/gm ASTM D 664 1.95 1.99 1.93 6 Sulphated
Ash % ASTM D 874 1.43 1.31 1.57 7 Viscosity Index ASTM D 2270 118
116 117 8 Flash Point, deg C. ASTM D 92 >190 >190 >190 9
Pour Point, deg C. ASTM D 97 -24 -24 -24 10 Evaporated Losses (%
max 250 ASTM D 5800 5.6 5.7 5.4 deg C.) 11 Cold Crank Simulator cP
@ -20 ASTM D 5293 >12000 >12000 >12000 deg C.) 12 High
Temperature High Shear, cP ASTM D 4863/ 7.9 7.8 8.1 5481 13 BPT, cP
ASTM D 4863 14 12 18 14 Low temp pumping viscosity, cp ASTM 4684
>300000 >300000 >300000 15 Copper strip corrosion at 100
deg C. ASTM D 130 1A 1A 1A 16 Conradson Carbon Residue ASTM D 189
2.5 2.23 2.78
[0097] The test results tabulated in table 1.2 indicate that there
is no significant change in the physico-chemical properties of the
nano suspension lubricant that may render the nano suspension
lubricant unsuitable for use in the automotive environment.
[0098] The tribological properties, such as friction resistance,
wear resistance, etc., of the copper based nano suspension
lubricant is also tested to evaluate improvements in lubricating
properties of the nano suspension lubricant. Table 1.3 illustrates
the same.
[0099] A detailed Tribological analysis and testing is being done
as per ASTM G99 standard on a pin on disc tribometer. Prior to
conducting the test, the discs are ground in a grinding machine and
ensured to be smooth uniformly. The surface roughness is checked
for all discs under testing and ensured that they are in the same
range (0.2-0.4 .mu.m Ra). This is done to ensure that all the tests
are conducted under the same conditions to achieve uniformity.
[0100] The test conditions are listed below: [0101] Load: 5, 10, 15
& 20 kgf [0102] Speed of rotation: 300, 600, 1200 RPM [0103]
Pin & Disc materials: Cast Iron
TABLE-US-00003 [0103] TABLE 1.3 Variation in coefficient of
friction of the copper based nano suspension lubricant at a range
of increasing speeds at constant loads Pin on disc results % Change
from base Average Coefficient of friction lubricant Speed Base Cu
Cu Cu Cu Cu Cu RPM lubricant 0.05% 0.1% 0.2% 0.05% 0.1% 0.2% 300
0.0383 0.0342 0.0307 0.0236 10.70 19.84 38.38 600 0.0405 0.0358
0.0332 0.0315 11.60 18.02 22.22 900 0.0466 0.0426 0.0338 0.0334
8.58 27.47 23.33 1200 0.0487 0.0436 0.0366 0.0358 50.47 24.85
26.49
It may be noted from the above table that the copper based nano
suspension lubricant exhibits improved friction resistance.
[0104] Tribological Testing with ASTM 4 Ball Wear Tester
[0105] The wear preventive and anti-friction properties of the
lubricants mixed with nano particles are being evaluated using ASTM
4 ball wear tester. As per ASTM D 4172, the wear preventive
properties of the nano suspension lubricant can be characterized
from the test results tabulated below.
TABLE-US-00004 TABLE 1.4 Variation in wear scar diameter with the
copper based nano suspension lubricant Lubricant Wear scar in micro
meters Base lubricant 554 Base lubricant + 0.05% Cu nano particles
455 Base lubricant + 0.1% Cu nano particles 432
[0106] It may be noted from the wear scar diameter has
substantially reduced with increase in the weight % of the surface
modified copper nano particles dispersed in the lubricating fluid.
This indicates improvement in wear preventive properties of the
copper based nano suspension lubricant.
[0107] X-Ray Diffraction (XRD) Analysis
[0108] Metallographic studies are conducted to assess the reduction
in wear due to use of the nano suspension lubricant according to an
example implementation. After conducting wear tests, the balls of
wear test are subjected to XRD analysis for analysis of the
possible deposition of the copper nano particles on surfaces of the
worn balls. FIG. 2 graphically illustrates the XRD analysis test
results for the copper based nano suspension lubricant according to
an example implementation. The graph 200 shown in FIG. 2 depicts
the amount of deposition of the copper nano particles present in
the nano suspension lubricant onto the worn out surfaces of the
metallic balls. In x-axis a diffraction angle of the X-ray
diffraction is plotted and in the y-axis the amount of deposition
of the copper nano particles on the surface of the worn our
metallic balls is depicted. The diffraction angle is measured in
degrees and the amount of deposition is expressed in an arbitrary
unit of number of cycles of measurement in the XRD. From the FIG. 2
it may be noted that along with iron (Fe), Nickel (Ni), Chromium
(Cr) and oxygen (O) copper (Cu) can also be seen at peaks of the
graph 200. This suggests deposition of the copper nano particles on
the surface of the worn out balls and form a protective coating
thereby offering resistance to wear.
[0109] Friction Test as Per ASTM D 5183 Standard
[0110] The friction test has been conducted to determine the
coefficient of friction of the copper based nano suspension
lubricant under the following prescribed test conditions using the
ASTM 4 Ball wear tester.
[0111] The test is conducted under the following test conditions:
[0112] Temperature 75.+-.2.degree. C. [0113] Speed 600 RPM [0114]
Duration 10 min at each load starting from 10 kgf [0115] Load 98.1
N (10 kgf) per 10 min increment to a load that indicates incipient
seizure, i.e., sudden increase in friction force value over steady
state on the friction trace.
TABLE-US-00005 [0115] TABLE 1.5 Variation in coefficient of
friction of the copper based nano suspension lubricant with
increasing loads at a constant speed Oil coefficient oil seizure
load of friction Base lubricant 120 0.11 Base lubricant + 0.05% Cu
nano particles 140 0.095 Base lubricant + 0.1% Cu nano particles
150 0.088
[0116] Thus, the test results depicted in the Table 1.5 suggest
that the coefficient of friction decreases with increase in the
surface modified copper nano particles dispersed in the lubricating
fluid and thus at 0.1 weight % of the surface modified copper nano
particles dispersed in the lubricating fluid the results are
optimum.
[0117] Tests Conducted on Roller Test Bench
[0118] Tests have been done using roller test bench with a
two-wheeler mounted on it. Hydraulic load is applied on the rollers
of the test bench and the rollers in turn apply braking action on
the rear wheel. Tests were carried out with the lubricating fluid
without nano particles and the lubricating fluid mixed with 0.05
weight % & 0.1 weight % of the surface modified copper nano
particles. The hydraulic loading is done by means of water forcing
through a dynamometer at a particular pressure. The pressure may be
regulated by operating a gate valve. To increase or decrease the
load, the gate valve is opened or closed thereby regulating the
pressure. The tests were carried out at constant speeds of 40, 50
& 50 KMPH at various gate openings of the dynamometer. The
initial gate opening is fixed at 40 KMPH and 2 kgf, 3 kgf & 4
kgf load respectively and the speed is increased with a
corresponding increase in load.
[0119] The rated brake power of the engine is 5.733 kW (7.8 HP) and
the testing was carried out up to a maximum load 8 kgf @ 60 KMPH
which corresponds to 3.5 kW of brake power or 62% of Maximum brake
power. The following sample results compare the results of the
lubricating fluid and lubricating fluid mixed with the surface
modified copper nano particles. From the results tabulated below it
can be observed that when the two-wheeler uses the lubricating
fluid mixed with surface modified copper nano particles better
mileage and brake thermal efficiency is obtained.
TABLE-US-00006 TABLE 1.6 Test results for roller test bench with
the copper based nano suspension lubricant % Change SPEED MILEAGE
LOAD N Brake tfc From base (KM/HR) (KM/LITRE) (KG) RPM power kW
kg/hr .eta..sub.bth lubricant Lubricating fluid 40 82.75 2.01
786.35 0.582 0.358 13.01 Lubricating fluid + 40 93.91 2.03 786.35
0.587 0.315 14.90 13.48 0.05% surface modified Cu nano particles
Lubricating fluid + 40 88.13 2.02 786.35 0.585 0.336 13.94 6.5 0.1%
surface modified Cu nano particles Lubricating fluid 40 76.23 3.01
786.35 0.869 0.388 17.91 Lubricating fluid + 40 79.01 3.03 786.35
0.876 0.375 18.70 3.64 0.05% surface modified Cu nano particles
Lubricating fluid + 40 81.85 3.06 786.35 0.883 0.362 19.54 7.34
0.1% surface modified Cu nano particles Lubricating fluid 40 63.51
4.08 786.35 1.178 0.466 20.22 Lubricating fluid + 40 64.48 4.03
786.35 1.163 0.459 21.01 1.5 0.05% surface modified Cu nano
particles Lubricating fluid + 40 70.29 4.05 786.35 1.171 0.421
22.25 10.67 0.1% surface modified Cu nano particles SPEED MILEAGE
LOAD N Brake tfc % (KM/HR) (KM/LITRE) (KG) RPM power kW kg/hr
.eta..sub.bth change Lubricating fluid 50 69.05 2.73 982.94 0.987
0.536 14.73 Lubricating fluid + 50 77.73 2.77 982.94 1.002 0.476
16.84 12.57 0.05% surface modified Cu nano particles Lubricating
fluid + 50 78.49 2.80 982.94 1.010 0.472 17.14 13.67 0.1% surface
modified Cu nano particles Lubricating fluid 50 61.03 4.32 982.94
1.562 0.606 20.61 Lubricating fluid + 50 65.53 4.30 982.94 1.552
0.566 21.98 7.37 0.05% surface modified Cu nano particles
Lubricating fluid + 50 67.94 4.30 982.94 1.552 0.545 22.79 11.32
0.1% surface modified Cu nano particles Lubricating fluid 50 50.81
6.00 982.94 2.168 0.729 23.82 Lubricating fluid + 50 53.06 5.93
982.94 2.140 0.698 24.54 4.42 0.05% surface modified Cu nano
particles Lubricating fluid + 50 56.54 5.97 982.94 2.158 0.655
26.38 11.27 0.1% surface modified Cu nano particles Lubricating
fluid 60 50.75 4.15 1179.52 1.801 0.875 16.47 Lubricating fluid +
60 65.34 4.04 1179.52 1.753 0.680 20.62 16.27 0.05% surface
modified Cu nano particles Lubricating fluid + 60 65.66 4.09
1179.52 1.772 0.677 20.96 22.34 0.1% surface modified Cu nano
particles Lubricating fluid 60 39.69 6.04 1179.52 2.618 1.119 18.72
Lubricating fluid + 60 41.83 6.04 1179.52 2.619 1.063 19.74 5.44
0.05% surface modified Cu nano particles Lubricating fluid + 60
46.67 6.02 1179.52 2.607 0.954 21.93 17.16 0.1% surface modified Cu
nano particles Lubricating fluid * the bike could not run at this
speed and load with the lubricating fluid Lubricating fluid + 60
32.73 8.00 1179.52 3.466 1.363 20.44 0.05% surface modified Cu nano
particles Lubricating fluid + 60 39.93 8.09 1179.52 3.508 1.121
25.24 0.1% surface modified Cu nano particles
[0120] It can be noted from the table 1.6 that at lower loads and
speeds, the percentage change in brake thermal efficiency is medium
and at higher loads and speeds it is quite high. It is also
observed that the lubricating fluid mixed with 0.1 weight % of the
surface modified copper nano particles gives best mileage at all
loads and speeds. It can be inferred that the optimum amount of the
surface modified copper nano particles to be added to the
lubricating fluid for best performance of the two-wheeler
corresponds to 0.1 weight %. Further increase in the weight % of
the surface modified copper nano particles in the lubricating
fluid, may increase viscous effects of the copper based nano
suspension lubricant thereby increasing pumping losses of the
engine and hence decreasing mileage of the engine.
[0121] Test for Deceleration of the Two-Wheeler
[0122] The friction in moving parts of an engine of the two-wheeler
is directly related to acceleration and deceleration of the
two-wheeler. A high acceleration and low deceleration of the
two-wheeler infers lesser friction in the moving parts. The test
method of assessing the reduction in friction of the moving parts
is being done by noting the acceleration and deceleration of the
two-wheeler. The two-wheeler is accelerated to 60 KMPH speed and
the power of the two-wheeler is switched off. The time required by
the two-wheeler to decelerate from 60 KMPH to 0 KMPH is noted down.
The results are tabulated below.
TABLE-US-00007 TABLE 1.7 Variation in deceleration time with the
copper based nano suspension lubricant Deceleration time in seconds
Base lubricant + 0.05% cu nano Base lubricant + Load Base lubricant
particles 0.1% cu nano particles 2 8.21 secs 8.58 9.51 3 6.86 7.25
8.15 4 6.56 6.88 7.10
It may be observed from Table 1.7 that the copper based
nano-suspension lubricant has taken more time for deceleration than
the lubricating fluid without any nano particle dispersed in it.
This suggests that the friction in the moving parts of the
two-wheeler while using the copper nano suspension lubricant is
less and thus loss of energy due to friction is reduced.
[0123] Field Test on Actual Road Conditions
[0124] Field tests have been conducted in actual road conditions at
different speeds and different loads on the two-wheeler. 10
observations were made at each load and speed taking a sample of
250 ml of petrol in each observation. The results of the test are
tabulated below.
Acceleration (Pickup) of the Two-Wheeler in Road Conditions with
160 kg Load (2 Persons)
TABLE-US-00008 TABLE 1.8 Variations in acceleration time with
copper based nano suspension lubricant Acceleration time is seconds
(0-60 KMPH) With base lubricant 6.12 s Acceleration with base
lubricant + 0.05% cu nano particles 5.65 s Acceleration with base
lubricant + 0.1% cu nano particles 5.34 s
From table 1.8 it may be observed that the acceleration time has
reduced and hence the pickup of the two-wheeler has increased.
There has also been observed substantial increase in mileage of the
two-wheeler with use of the copper based nano suspension based
lubricant. The test results illustrating the same have been
tabulated below in table 1.9.
TABLE-US-00009 TABLE 1.9 Variations in mileage with copper based
nano suspension lubricant Results of tests done in actual road
conditions 40 and 40 and 160 kgs load % increase 80 kgs load %
increase 50 % increase Oil 2 person) in mileage (1 person) in
mileage (2 persons) in mileage Base lubricant 72-75 76-80 68-40
Base lubricant + 73-77 2.04% 78-82 2.56% 70-74 4.34% 0.05% nano
particles Base lubricant + 76-84 8.84% 80-88 7.70% 74-80 11.60%
0.1% nano particles 50 % increase 60 % increase 60 % increase Oil
(1 person) in mileage (2 persons) in mileage (1 persons) in mileage
Base lubricant 71-73 53-55 54.56 Base lubricant + 74-78 5.55% 59.66
15.74% 60-67 15.45% 0.05% nano particles Base lubricant + 76-82
9.72% 60-66 16.60% 61-67 16.30% 0.1% nano particles indicates data
missing or illegible when filed
[0125] Exhaust Gas Analysis on Four Stoke Bike
[0126] A typical exhaust gas analysis on a 4 stroke bike with the
copper based nano suspension lubricant is presented in the table
1.10.
TABLE-US-00010 TABLE 1.10 Variations in emission properties for the
copper based nano suspension lubricant Results of Exhaust gas
analysis Lubricant CO CO2 HC NOX Bass lubricant 2.587% 8.36% 485
PPM 71 PPM Base lubricant + 0.05% Cu 2.873% 7.01% 446 PPM 28 PPM
Bass lubricant + 0.1% Cu 2.672% 7.15% 489 PPM 15 PPM
[0127] From table 1.10 it may be noted that the emission of
poisonous gases such as, CO.sub.2, HC and NOX are substantially
reduced when the lubricating fluid is mixed with the surface
modified copper nano particles.
Example 2
MoS.sub.2 Based Nano Suspension Lubricant
[0128] The nano suspension lubricant described herein can be based
on a number of different exemplary compositions. In example 1,
metallic copper can be used as a nano particle to be dispersed into
the lubricating fluid. Likewise, metallic sulphides such as,
molybdenum sulphide is used as a nano particle in the nano
suspension lubricant. Typically, the surfactants used for modifying
the surface of the metallic sulphides are cationic surfactants. The
cationic surfactant molecules carry a positive charge at the
hydrophilic end of the surfactant molecule. Examples of cationic
surfactants include quaternary ammonium salts, cetrimonium bromide
(CTAB), etc. Thus, according to an example implementation of the
present subject matter, the nano suspension lubricant includes
surface modified molybdenum disulphide nano particles from about
0.05 weight % to 0.1 weight % dispersed in the lubricating fluid.
The lubricant fluid includes about 90% to 99% base oil, such as,
petroleum fractions, mineral oils, vegetable oils, synthetic oils,
solvent refined mineral oils, hydrocracked mineral oils,
polyalphaolefins, polyalkylglycols, synthetic esters, and the like.
The lubricating fluid also includes about 1% to 10% additives, such
as, antioxidants, detergents, and antiwear agents. The molybdenum
disulphide (MoS.sub.2) nano particles are coated with sorbitan
monooleate surfactant in a similar method as employed for coating
the copper nano particles with lauric acid in the example 1 to
obtain surface modified MoS.sub.2 nano particles. The surface
modified molybdenum disulphide nano particles from about 0.05
weight % to 0.1 weight % are dispersed in the lubricating fluid by
stirring for about 1 hour in an ultra sound sonicator. The
MoS.sub.2 nano particles used have a size less that about 100
nanometers. In an example, Silane can be used for being coated on
the MoS.sub.2 nano particles for surface modification of the
MoS.sub.2 nano particles.
[0129] Evaluation of Stability of Lubricating Oil Suspension
Containing the Surface Modified MoS.sub.2 Nano Particles Using
Light Scattering Techniques
[0130] Dynamic light scattering (DLS) is a technique used to
determine the size distribution profile of small particles in
suspension or polymers in a mixture. The stability of any
suspension is measured in terms of relative change in average
particle size of the dispersed particles in the suspension. In a
good suspension the size of the particles remain more or less same
over a period of time. The stability of the surface modified
MoS.sub.2 nano particles in lubricating fluid is tested using DLS.
The stability of the suspension in terms of average particle size
is investigated over a period of 2 months. The variation of the
MoS.sub.2 nano particles surface modified with Sorbitan Monooleate
is shown in the following table.
TABLE-US-00011 TABLE 2.1 The average particle size of the surface
modified MoS.sub.2 nano particles over a period of 60 days Average
particle size of surface modified MoS.sub.2 nano particles Day
expressed in nanometers (nm) 1.sup.st Day 308.1 15.sup.th Day 293.3
30.sup.th Day 376.8 60.sup.th Day 392.2
As may be understood from the table 2.1, the average particle size
of the surface modified MoS.sub.2 nano particles over a period of
60 days did not have substantial change. This indicates good steric
repulsions between the surface modified MoS.sub.2 nano particles.
Thus, in case of MoS.sub.2 nano particles, the Sorbitan Monooleate
keeps the suspension of the modified MoS.sub.2 nano particles in
the lubricating fluid stable.
[0131] In an example implementation, the MoS.sub.2 based nano
suspension lubricant described herein can be used for lubrication
in vehicles the automotive industry. Thus, to determine the
suitability of the MoS.sub.2 based nano suspension lubricant in the
automotive industry evaluation of physico chemical properties of
the MoS.sub.2 based nano suspension lubricant becomes necessary.
The physico-chemical properties of a lubricant include viscosity
index, total acid number, total base number of a nano suspension
lubricant that determine the suitability of the nano suspension
lubricant for use in vehicles, such as in engines of two-wheelers
and four-wheelers. In particular, the physico-chemical properties
of the nano suspension lubricants are evaluated to investigate the
suitability of the surfactant and the surface modification process
to the automotive environment.
[0132] Further, a nano suspension lubricant exhibits different
physico-chemical properties depending on a kind of base oil used in
the lubricating fluid. Accordingly, test results are illustrated
below for the MoS.sub.2 based nano suspension lubricant including
lubricating fluids having different compositions for the base
oil.
[0133] Tests for Physico-Chemical Properties
[0134] In an example implementation to analyze the physico-chemical
properties of the MoS.sub.2 based nano suspension lubricant,
different tests such as Kinematic viscosity test, total acid number
test, total base number test, and copper strip corrosion test are
performed.
[0135] Kinematic Viscosity Test
[0136] Viscosity of the nano suspension lubricant is closely
related to its ability to reduce friction. Viscosity index is a
parameter that indicates the variation of viscosity with
temperature. The Viscosity index is calculated as per ASTM D 445
standard by measuring viscosity of the MoS.sub.2 based nano
suspension lubricant at 40.degree. C. and 100.degree. C. A high
value (normally >90) of the viscosity index indicates that the
nano suspension lubricant has good lubricating properties.
TABLE-US-00012 TABLE 2.2 Viscosity index for the MoS.sub.2 based
nano suspension lubricant with SM petrol engine oil (SAE 20 W 40)
as the lubricating fluid Lubricant used Viscosity index Petrol
engine oil SM grade >110 (SAE 20 W 40) + 0.05 MoS.sub.2 Petrol
engine oil SM grade >110 (SAE 20 W 40) + 0.1 MoS.sub.2
TABLE-US-00013 TABLE 2.3 Viscosity index for the MoS.sub.2 based
nano suspension lubricant with diesel engine oil CI 4 grade (SAE 20
W 40) as the lubricating fluid Lubricant used Viscosity index
Diesel engine oil CI 4 (SAE >110 15 W 40) + 0.05 MoS.sub.2
Diesel engine oil CI 4 (SAE >110 15 W 40) + 0.1 MoS.sub.2
[0137] Total Acid Number Test
[0138] Total Acid Number (TAN) is a measure of presence of acids
within the nano suspension lubricant. The Total Acid Number is the
amount of potassium hydroxide in milligrams that is needed to
neutralize the acids in one gram of the nano suspension lubricant.
The TAN value indicates potential corrosiveness of the nano
suspension lubricant. Thus, maintaining a low TAN value is
essential to maintain and protect components of engines. Generally,
a low TAN value (<3) gives an indication that the nano
suspension lubricant is non-corrosive. The table below illustrates
the TAN values of the MoS.sub.2 based nano suspension lubricant
including surface modified MoS.sub.2 nano particles dispersed in
different lubricating fluids having different base oil
compositions.
TABLE-US-00014 TABLE 2.4 Total Acid number with MoS.sub.2 based
nano suspension lubricant having petrol engine oil SM grade (SAE 20
W 40) as the lubricating fluid Lubricant used Total Acid number
Petrol engine oil SM grade (SAE <2 20 W 40) Petrol engine oil SM
grade (SAE <2 20 W 40) + 0.05 MoS.sub.2 Petrol engine oil SM
grade (SAE <2 20 W 40) + 0.1 MoS.sub.2
TABLE-US-00015 TABLE 2.5 Total Acid number with MoS.sub.2 based
nano suspension lubricant having diesel engine oil CI4 grade (SAE
15 W 40) as the lubricating fluid Lubricant used Total Acid number
Diesel engine oil CI4 grade (SAE <2.2 15 W 40) Diesel engine oil
CI4 grade (SAE <2.2 15 W 40) + 0.05 MoS.sub.2 Diesel engine oil
CI4 grade (SAE <2.2 15 W 40) + 0.1 MoS.sub.2
[0139] Thus, as may be understood from the tables above, the Total
Acid Number of the nano suspension lubricant dispersed with surface
modified MoS.sub.2 nano particles does not result in substantial
change or deterioration of the total acid number of the nano
suspension lubricant and is suitable for use in the automotive
industry.
[0140] Total Base Number Test
[0141] The nano suspension lubricant is required to prevent acidic
corrosion within the combustion chamber of a running engine and
should protect different engine components, such as, piston rings,
cylinder liner and piston crown from damage by sulphur or nitrogen
containing acids. The Total Base Number (TBN) of the nano
suspension lubricant determines how effectively acids formed during
combustion process of the engine are reduced. The higher the TBN
(typically >9), the more effective the nano suspension lubricant
is in suspending wear-causing contaminants and reducing the
corrosive effects of acids over an extended period of time.
Typically, the TBN of the nano suspension lubricant is measured by
the ASTM D 2896 standard potentiometric titration with perchloric
acid. The TBN of the nano suspension lubricant may vary depending
on the different kinds of lubricating fluid that is being used. For
example, depending on the composition of the lubricating fluid,
i.e., the kind of base oil and additives used in the lubricating
fluid, the TBN of the nano suspension lubricant may differ. The
tables below illustrate the TBN values of the MoS.sub.2 based nano
suspension lubricant including surface modified MoS.sub.2 nano
particles dispersed in different lubricating fluids having
different base oil compositions.
TABLE-US-00016 TABLE 2.6 Total Base number with the MoS.sub.2 based
nano suspension lubricant having diesel engine oil CI4 grade (SAE
15 W 40) as the lubricating fluid Lubricant used Total Base number
Diesel Engine oil CI4 grade >10 Diesel Engine oil CI4 grade +
0.1% >10 surface modified MoS.sub.2 nano particles with
surfactant SPAN 80 Diesel Engine oil CI4 grade + 0.1% >10
surface modified MoS.sub.2 nano particles with surfactant
Silane
TABLE-US-00017 TABLE 2.7 Total Base number with MoS2 nano
suspension lubricant having petrol engine oil SM grade (SAE 20 W
40) as the lubricating fluid Lubricant used Total Base number
Petrol engine oil >6 Petrol engine oil + 0.1% surface modified
>6 MoS.sub.2 nano particles with surfactant SPAN 80 Petrol
engine oil + 0.1% surface >6 modified MoS.sub.2 nano particles
with surfactant Silane
[0142] Copper Strip Corrosion Test
[0143] The Copper Strip Corrosion Test is carried out to assess the
relative degree of corrosiveness of a number of petroleum products,
including aviation fuels, automotive gasoline, lubricating oils and
other products. Hence, the copper strip corrosion test is performed
for the MoS.sub.2 based nano suspension lubricant. In the test, a
classification number from 1-4 is assigned based on a comparison
with the ASTM Copper Strip Corrosion Standards. A value of 1a, 1b,
and 1c indicates corrosion protection provided by the MoS.sub.2
based nano suspension lubricant under test. Further, it may be
understood by a person skilled in the art that the value of 1a
denotes excellent protection, 1b denotes good protection, and 1c
denotes sufficient protection provided by the MoS.sub.2 based nano
suspension lubricant.
[0144] In these tests, the petrol engine oil of SM 4 grade is
selected as the lubricating oil. The lubricating oil mixed with
MoS.sub.2 was tested for copper strip corrosion test at 100.degree.
C. for 3 hours and their tarnish level was assessed against the
ASTM Copper Strip Corrosion Standard.
[0145] The results are shown in the table below.
TABLE-US-00018 TABLE 2.8 Copper strip corrosion test results for
the MoS.sub.2 based nano suspension lubricant Lubricant used Copper
strip corrosion result Petrol engine oil of SM grade 1a Petrol
engine oil of SM grade + 1a surface modified MoS.sub.2 nano
particles using surfactant sorbitan monooleate Petrol engine oil of
SM grade + 1b surface modified MoS.sub.2 nano particles using
surfactant Silane
[0146] From the above test results of the physico-chemical
properties of the MoS.sub.2 based nano suspension lubricant, it may
concluded that the surface modified MoS.sub.2 nano particles have
no substantial effect on the total acid number and the total base
number of the MoS.sub.2 based nano suspension lubricant. Thus, it
may concluded that there is no abnormal deterioration of the
physico-chemical properties of the MoS.sub.2 based nano suspension
lubricant and hence the MoS.sub.2 based nano suspension lubricant
is suitable for the automotive environment.
[0147] Further, in order to assess the tribological properties,
such as friction resistance, wear resistance, etc., of the nano
suspension lubricant, wear and friction tests are performed on the
MoS.sub.2 based nano suspension lubricant. The wear and friction
tests are conducted for the surface modified MoS.sub.2 nano
particles dispersed in different lubricating fluids.
[0148] Four Ball Wear Test
[0149] The Four Ball Wear Test determines the wear protection
properties of a lubricant. The wear tests are conducted for each of
petrol engine oil and diesel engine oil as the lubricating fluid at
40 kgf load and 60 kgf load. The wear tests on gear oils of GL 4
grade are conducted at 40 kgf and 80 kgf loads. The wear scar
diameters (WSD) on the stationary balls were measured using a
Metallurgical microscope.
[0150] FIGS. 3(a)-3(h) illustrate the wear test results for the
MoS.sub.2 based nano suspension lubricant with the surface modified
MoS.sub.2 nano particles suspended in different lubricating fluids,
according to an example implementation. In the graphs illustrated
in the FIGS. 3(a)-3(h), the y-axis depicts the wear scar diameter
and the x-axis depicts different compositions of the MoS.sub.2
based nano suspension lubricant with different lubricating fluids,
such as diesel engine oil, petrol engine oil, and gear oil. The
wear scar diameter is represented in microns.
[0151] The graph 300(a) illustrated in FIG. 3(a) depicts the wear
test results of the MoS.sub.2 based nano suspension lubricant
having diesel engine oil of CI 4 grade as the lubricating fluid at
40 Kgf load, according to an example implementation. It may be
noted from the graph 300(a) that the wear scar diameter is greater
without the MoS.sub.2 nano particles dispersed in the lubricating
fluid and on mixing the MoS.sub.2 nano particles in the lubricating
fluid the wear scar diameter substantially reduces.
[0152] The graph 300(b) illustrated in FIG. 3(b) depicts the wear
test results of the MoS.sub.2 based nano suspension lubricant
having diesel engine oil of CI 4 grade as the lubricating fluid at
60 Kgf load, according to an example implementation. It may be
noted that minimum wear scar diameter or in other words, maximum
wear protection is possible when the lubricating fluid is mixed
with 0.1 weight % of MoS.sub.2 nano particles.
[0153] The graph 300(c) illustrated in FIG. 3(c) depicts the wear
test results of the MoS.sub.2 based nano suspension lubricant
having petrol engine oil of SM grade as the lubricating fluid at 40
Kgf load, according to an example implementation. It may be noted
that optimum wear protection is possible when 0.1 weight % of
MoS.sub.2 nano particles is mixed in the lubricating fluid.
[0154] The graph 300(d) illustrated in FIG. 3(d) depicts the wear
test results of the MoS.sub.2 based nano suspension lubricant
having petrol engine oil of SM grade as the lubricating fluid at 60
Kgf load, according to an example implementation. Again, minimum
wear scar diameter at 0.1% MoS.sub.2 is mixed in the lubricating
fluid.
[0155] The wear properties of the MoS.sub.2 based nano suspension
lubricant having gear oil of GL 4 grade as the lubricating fluid
are also tested. The gear oil of GL 4 grade having two different
viscosity grades, such as EP 140 and SAE 80 W 90 have been used for
the tests. The graph 300(e) illustrated in FIG. 3(e) depicts the
wear test results of MoS.sub.2 based nano suspension lubricant
having gear oil of GL 4 grade with viscosity grade SAE 80 W 90 as
the lubricating fluid at 40 Kgf load, according to an example
implementation. The gear oil having 0.1% of MoS.sub.2 nano
particles dispersed in it shows optimal results with minimum scar
diameter. The graph 300(f) illustrated in FIG. 3(f) depicts the
wear test results of MoS.sub.2 based nano suspension lubricant
having gear oil of GL 4 grade with viscosity grade SAE 80 W 90 as
the lubricating fluid at 80 Kgf load, according to an example
implementation. As can be seen from the graph 300(f), the gear oil
having 0.05% of MoS.sub.2 nano particles dispersed in it shows
optimal results with minimum wear scar diameter value of
512.42.
[0156] The graph 300(g) illustrated in FIG. 3(g) depicts the wear
test results of the MoS.sub.2 based nano suspension lubricant
having gear oil of GL 4 grade with viscosity grade EP 140 as the
lubricating fluid at 40 Kgf load, according to an example
implementation. The gear oil mixed with the MoS.sub.2 nano
particles shows substantial improvement in wear protective
properties, as can be understood from the graph 300(f).
[0157] The graph 300(h) illustrated in FIG. 3(h) depicts the wear
test results of the MoS.sub.2 based nano suspension lubricant
having gear oil of GL 4 grade with viscosity grade EP 140 as the
lubricating fluid at 80 Kgf load, according to an example
implementation.
[0158] From the above graphical illustrations it may be concluded
that based on the lubricating oil an optimum weight percentage of
the nano particles may be chosen for best performance. As may be
observed from the graphs, in general, the optimum weight % of the
surface modified MoS.sub.2 nano particles for best results lies
between 0.05% to 0.1%.
[0159] Further, to determine the tribological properties of the
MoS.sub.2 based nano suspension lubricant friction tests as per
ASTM D 5183 standard have been performed. The frictions tests have
been conducted to determine the coefficient of friction of the
MoS.sub.2 based nano suspension lubricant under the following
prescribed test conditions using ASTM 4 Ball wear test machine.
TABLE-US-00019 Temperature 75 .+-. 2.degree. C. Speed 600 RPM
Duration 10 min at each load starting from 10 kgf Load 98.1N (10
kgf) per 10 min increment to a load that indicates incipient
seizure (sudden increase in friction force value over steady state)
on the friction trace
[0160] FIGS. 4(a)-4(h) graphically illustrate the friction test
results for the MoS.sub.2 based nano suspension lubricant with the
surface modified MoS.sub.2 nano particles suspended in different
lubricating fluids, according to an example implementation. In the
graphs 400(a), 400(c), 400(e), and 400(g) illustrated in the FIGS.
4(a), 4(c), 4(e), and 4(g) the y-axis depicts the coefficient of
friction of the MoS.sub.2 based nano suspension lubricants and the
x-axis depicts different compositions of the MoS.sub.2 based nano
suspension lubricant with varying percentages of the MoS.sub.2 nano
particles dispersed in the lubricating fluid. In the graphs
illustrated in 400(b), 400(d),400(f), and 400(h) the y-axis depicts
seizure load and the x-axis depicts different compositions of the
MoS.sub.2 based nano suspension lubricant with varying percentages
of the MoS.sub.2 nano particles dispersed in the lubricating
fluid.
[0161] The graph 400(a) illustrates the variations in the
coefficient of friction in MoS.sub.2 based nano suspension
lubricant having diesel engine oil of CI 4 grade as the lubricating
fluid, according to an example implementation. It may be noted from
the 400(a) that the coefficient of friction of the lubricating
fluid, i.e., CI 4 grade diesel engine oil is greater without the
MoS.sub.2 nano particles and on mixing the surface modified
MoS.sub.2 nano particles in the lubricating fluid the coefficient
of friction substantially reduces. This reduces the frictional
force between the moving mechanical components in the engine.
[0162] The graph 400(b) illustrates the variations in seizure load
of the MoS.sub.2 based nano suspension lubricant having diesel
engine oil of CI 4 grade as the lubricating fluid, according to an
example implementation. It may be noted that when the lubricating
fluid, i.e., diesel engine oil of CI 4 grade in this case, is mixed
with 0.05% of the surface modified MoS.sub.2 nano particles, the
nano suspension lubricant can endure a maximum seizure load of up
to 140 Kgf.
[0163] The graph 400(c) illustrates the variations in the
coefficient of friction in the MoS.sub.2 based nano suspension
lubricant having petrol engine oil of SM grade as the lubricating
fluid, according to an example implementation. It may be noted,
that the nano suspension lubricant having 0.05% of the surface
modified MoS.sub.2 nano particles dispersed in the lubricating
fluid has a minimum coefficient of friction value of 0.0908. Thus,
it may be concluded that the mentioned composition has optimal
friction resistance properties.
[0164] The graph 400(d) illustrates the variations in seizure load
of the MoS.sub.2 based nano suspension lubricant having petrol
engine oil of SM grade as the lubricating fluid, according to an
example implementation. The graph 400(d) depicts that the MoS.sub.2
based nano suspension lubricant having 0.05% of the surface
modified MoS.sub.2 nano particles dispersed in the lubricating
fluid can endure a maximum seizure load of up to 140 Kgf.
[0165] In an example, a lubricating oil such as gear oil of GI 4
grade oil having two different viscosity grades, such as EP 140 and
SAE 80 W 90 have been used for the tests. The graph 400(e)
illustrates the variations in the coefficient of friction in the
MoS.sub.2 based nano suspension lubricant having gear oil of GL 4
grade of viscosity grade SAE 80 W 90 as the lubricating fluid,
according to an example implementation. The gear oil having 0.05%
of the surface modified MoS.sub.2 nano particles dispersed in it
shows optimal results with a minimum value of friction coefficient
of 0.071. The graph 400(f) illustrates the variations in seizure
load of the MoS.sub.2 based nano suspension lubricant having gear
oil of GL 4 grade with viscosity grade SAE 80 W 90 as the
lubricating fluid, according to an example implementation. As can
be seen from the graph 400(f), the gear oil having 0.05% of the
surface modified MoS.sub.2 nano particles and 0.1% of the surface
modified MoS.sub.2 nano particles dispersed in the lubricating
fluid can endure a maximum seizure load of up to 160 Kgf.
[0166] The graph 400(g) illustrates the variations in the
coefficient of friction in the MoS.sub.2 based nano suspension
lubricant having gear oil of GL 4 grade of viscosity grade EP 140
as the lubricating fluid, according to an example implementation.
The gear oil mixed with the MoS.sub.2 nano particles shows
substantial improvement in friction protective properties, as can
be understood from the graph 400(g). A minimum coefficient of
friction value of 0.071 is observed for 0.05% of the surface
modified MoS.sub.2 nano particles mixed in the lubricating fluid,
i.e., the gear oil.
[0167] The graph 400(h) illustrates the variations in seizure load
of the MoS.sub.2 based nano suspension lubricant having gear oil of
GL 4 grade of viscosity grade EP 140 as the lubricating fluid,
according to an example implementation. As can be seen from the
graph 400(h) the gear oil having 0.05% of the surface modified
MoS.sub.2 nano particles dispersed in the gear oil can endure a
maximum seizure load of up to 160 Kgf.
[0168] Thus, from the above friction test results it may be
concluded that the MoS.sub.2 based nano suspension lubricant
evidences substantially improved friction properties with endurance
over higher seizure loads. Further, for optimum results the surface
modified MoS.sub.2 nano particles between 0.05 weight % to 0.1
weight % can be mixed in the lubricating fluid.
[0169] Extreme pressure lubricants, such as gear oils are designed
for use in severe applications across a variety of conditions,
including high load, moisture and a wide range of operating speeds
and loads. Thus, extreme pressure (EP) properties of the MoS.sub.2
based nano suspension lubricant with the gear oil as the
lubricating fluid are tested.
[0170] Evaluation of EP Properties of the Nano Suspension Lubricant
Using ASTM D 2783 Standard
[0171] The EP test determines the load carrying properties of the
nano suspension lubricant. Generally, two parameters, such as
Load-wear index and Weld load are evaluated to make this
determination. Higher the value of the load wear index and weld
load for a lubricant, the lubricant may be understood to have
better EP properties.
[0172] The EP tests are carried out on the MoS.sub.2 based nano
suspension lubricant having Gear oils of GL4 grade of viscosity
grade SAE 80 W 90 and EP 140 as the lubricant fluid.
[0173] FIGS. 5(a)-5(d) graphically illustrates the variation of
extreme pressure (EP) properties of the MoS.sub.2 based nano
suspension lubricant, according to an example implementation. The
results of Table 2.13 are plotted in the graphs 500(a) and 500(b)
illustrated in FIGS. 5(a) and 5(b), respectively. The graph 500(a))
depicts the variation in Load wear index of the MoS.sub.2 based
nano suspension lubricant having gear oil of GL 4 grade with
viscosity grade of SAE 80 W 90 as the lubricating fluid. The y-axis
of the graph 500(a) illustrated in FIG. 5(a) depicts the load-wear
index and the x-axis depicts different compositions of the
MoS.sub.2 based nano suspension lubricant, varying in the weight %
of the surface modified MoS.sub.2 nano particles mixed in the
lubricating fluid. The graph 500(b) depicts the variation in weld
load of the MoS.sub.2 based nano suspension lubricant having gear
oil of GL 4 grade with viscosity grade of SAE 80 W 90 as the
lubricating fluid, according to an example implementation. The
y-axis of the graph 500(b) represents the weld load and the x-axis
depicts different compositions of the MoS.sub.2 based nano
suspension lubricant, varying in the weight % of the surface
modified MoS.sub.2 nano particles mixed in the lubricating fluid.
The weld load is represented in Kgf.
[0174] The graph 500(c) illustrates the variation in Load wear
index of the MoS.sub.2 based nano suspension lubricant having gear
oil of GL 4 grade with viscosity grade of EP 140 as the lubricating
fluid, according to an example implementation. The results of the
Table 2.14 are plotted in the graphs 500(c) and 500(d). The y-axis
of the graph 500(c) depicts the load-wear index and the x-axis
depicts different compositions of the MoS.sub.2 based nano
suspension lubricant. The graph 500(d) depicts the variation in
weld load of the MoS.sub.2 based nano suspension lubricant having
gear oil of GL 4 grade with viscosity grade of EP 140 as the
lubricating fluid, according to an example implementation. It may
be noted that with addition of the surface modified MoS.sub.2 nano
particles from 0.5 weight % to 0.1 weight % into the lubricating
fluid, the weld load characteristics have substantially improved.
Particularly, it may be noted that on mixing 0.1 weight % of the
surface modified MoS.sub.2 nano particles in the lubricating fluid,
the lubricant can endure a weld load as high as 280 Kgf.
[0175] Further, to determine the wear characteristics of the
MoS.sub.2 based nano suspension lubricant, metallographic studies
of worn out metallic balls used in the wear test can be performed.
The scar area of the worn out metallic balls after the wear test
are magnified in a Scanning Electron Microscope (SEM) and observed
for deposition of particles on the worn out surface of the balls.
On viewing the balls in the SEM deposition of nano particles on the
surface of the worn out balls can be seen. FIG. 6 illustrates
characterization of the worn out balls on scanning electron
microscope with X-ray diffraction attachment, according to an
example implementation.
[0176] The graph 602 in FIG. 6 depicts the deposition of particles
on the worn out balls when the lubricating fluid, such as gear oil
GL 4 grade is being used. The graph 604 depicts the deposition of
particles on the worn out balls when the lubricating fluid, such as
gear oil of GL 4 grade mixed with 0.05 weight % of the surface
modified MoS.sub.2 nano particles is being used for lubrication.
The graph 606 depicts the deposition of particles on the worn out
balls when the lubricating fluid, such as gear oil GL 4 grade mixed
with 0.10 weight % of the surface modified MoS.sub.2 nano particles
is being used for lubrication. The y-axis of the graphs 602, 604,
and 606 depict the amount of deposition of the nano particles on
the moving components of an engine and the x-axis depicts the
energy of the x-ray radiation used by the SEM. The energy of the
x-ray radiation is represented in Kilo electron volts (Kev). In the
graph 604, at peak 607 it may be noted that, the surface modified
MoS.sub.2 nano particles result in deposition of Molybdenum (Mo)
and sulphide (S) on the surface of the worn out balls thereby
providing wear resistance.
[0177] Performance Test on Petrol Engine Test Rig
[0178] The performance test with lubricating oil is carried out on
petrol engine by means of a specially designed test rig. The petrol
engine test rig consists of an 800 cc 3 cylinder mpfi petrol engine
of connected to an eddy current dynamometer. The morse test is
generally used to determine brake power or power available at a
crank shaft of the engine and various efficiencies of an engine.
Morse test is carried out at different speeds and loads to
determine various efficiencies of the engine with lubricants.
[0179] FIG. 7 illustrates graphical representations of variations
in brake thermal efficiency of the MoS.sub.2 based nano suspension
lubricant in a petrol engine test rig, according to an example
implementation.
[0180] The graph 700 illustrated in FIG. 7 depicts the variation of
brake thermal efficiency with brake power at 2500 RPM speed of the
engine and the graph 702 illustrated in FIG. 7 depicts the
variation of brake thermal efficiency with brake power at 4000 RPM
speed of the engine. In the graphs 700 and 702 the y-axes depicts
the brake thermal efficiency (.eta..sub.brake thermal) and the
x-axes depicts the brake power. The brake power is represented in
watts.
[0181] From the graphs 700 and 702, an improvement in the brake
thermal efficiency at lower as well as higher speeds of the engine
is observed with the MoS.sub.2 based nano suspension lubricant. The
MoS.sub.2 based nano suspension lubricant shows higher efficiency
improvement at lower loads and lower speeds of the engine.
[0182] Performance Testing on Diesel Engine Test Rig
[0183] The performance test with a diesel engine oils carried out
on Diesel engine test rig consisting of 1200 cc four cylinder, four
stroke, Turbocharged CRDI diesel engine connected to an eddy
current dynamometer for loading of the engine.
[0184] The specifications of the engine are as follows:
TABLE-US-00020 Type 4 Cylinder, 4 stroke, CRDI engine Ignition
microprocessor based engine management system(ECU), Displacement
1250 cc Bore and stroke Bore 69.6 mm, stroke 82 mm Maximum Power 55
kW @ 4000 rpm Maximum Torque 190 Nm @ 2500 rpm Lubricant SAE 15 W40
oil (factory recommended)
[0185] FIG. 8 graphically illustrates variations in brake thermal
efficiency of the MoS.sub.2 based nano suspension lubricant in a
diesel engine test rig, according to an example implementation. The
graph 800 illustrated in FIG. 8 depicts the variation of brake
thermal efficiency with brake power at 2500 RPM speed of the engine
and the graph 802 illustrated in FIG. 8 depicts the variation of
brake thermal efficiency with brake power at 4000 RPM speed of the
engine. In the graphs 800 and 802 the y-axis depicts the brake
thermal efficiency (.eta.brake thermal) and the x-axis depicts the
brake power. The brake power is represented in watts. It may be
understood from the FIG. 8 that the MoS.sub.2 based nano suspension
lubricant has enhanced brake thermal efficiency in the diesel
engine test rig.
[0186] Endurance Test for Wear and Life of Engine with the
MoS.sub.2 Based Nano Suspension Lubricant
[0187] The wear performance of lubricant is tested by subjecting
the engine lubricated with the MoS.sub.2 based nano suspension
lubricant to 80 hour test under cyclic loading on a test rig. The
engine test rig consists of a 100 cc single cylinder petrol engine
connected to an alternating current dynamometer.
[0188] The specifications of the engine are as follows:
TABLE-US-00021 Type Single Cylinder, 4 stroke, Twin spark
Displacement 100 cc Bore .times. stroke 50 mm .times. 49.5 mm
Compression Ratio 8.8:1 Maximum Power 7.8 bhp @ 7500 rpm Maximum
Torque 8 Nm @ 4500 rpm Ignition System Digital Electronic Ignition
Engine Start Electric/Kick Maximum speed 7500 RPM
[0189] The alternating current dynamometer is used for loading the
engine. The speed of dynamometer, voltage & current developed
by dynamometer, fuel consumption and temperature of exhaust gases
are measured. The cyclic loading is conducted with 16 cycles of 5
hrs cyclic loading. The cyclic loading of 21/2 hour is done as per
the sequence given in following table.
TABLE-US-00022 TABLE 2.9 Cyclic loading sequence for endurance test
Test hours Test Conditions 2 hr 75% of full load at declared max
speed 2 hr 100% load at speed to maximum torque 10 min Idling 50
min 100% load at declared max speed.
[0190] After the completion of the endurance test, the engine is
dismantled and the conditions of the aforementioned design
features, such as the cylinder liner of the engine and the piston
rings are inspected for possible wear and tear. The wear of the
cylinder liner is measured in terms of increase in diameter of the
cylinder liner. The readings of diameter of the cylinder liner
before & after the test are noted down and the difference is
reported as wear loss of the cylinder liner. The wear losses of the
cylinder liner for the MOS.sub.2 based nano suspension lubricant is
given in the table below.
TABLE-US-00023 TABLE 2.10.1 Results of wear of the cylinder liner
with the MOS.sub.2 based nano suspension lubricant at different
positions of the cylinder Cylinder liner wear in .mu.m Position
from petrol engine oil + 0.1% TDC in cm petrol engine oil surface
modified MoS.sub.2 2 5.0 4.5 4 6.5 4.75 4 7.5 4.75 8 7.55 3.0 Mean
Wear in .mu.m 6.64 4.25
Another parameter to be determined for determination of endurance
of the engine is the wear of the piston rings in the engine. The
wear of the piston rings are reported in terms of weight loss of
the piston rings. The test results for weight loss of the piston
rings are tabulated below.
TABLE-US-00024 TABLE 2.10.2 Results for weight loss of the piston
rings and gudgeon ring in 80 hr test oil petrol engine oil + 0.1%
surface modified petrol engine oil MoS.sub.2 Piston rings. Serial
Weight loss mg Weight loss mg Compression ring 1 1IP 2 1
Compression ring 1 2IP 18 11 Expanding ring E1 2 1 Oil ring 1 1SR 7
4 Oil ring 2 2SR 5 2 Total weight loss, mg 34 17 Gudgeon pin wear,
mg 11 7
[0191] It may be noted from the Table 2.10.2 that the nano
suspension lubricant having the MoS.sub.2 nano particles dispersed
therein have substantially reduced the wear in the piston rings and
the cylinder liners of the engine. Thus, the MoS.sub.2 based nano
suspension lubricant offers better endurance to the engine.
[0192] Fuel Consumption Test
[0193] The fuel consumption is measured during the endurance test
at an interval of 2 hours to assess the fuel efficiency of the nano
suspension lubricant. The fuel consumption at an instant and total
fuel consumption were recorded and tabulated in the table given
below.
TABLE-US-00025 TABLE 2.11 Total fuel consumption rates during 80 Hr
test Total fuel Percentage Lubricant used consumed in litres
improvement Lubricating fluid (petrol engine 93.300 oil)
Lubricating fluid + 0.1% surface 83.440 10.568 modified MoS.sub.2
nano particles
[0194] The results tabulated in the Table 2.11 is plotted in the
graph 900 of FIG. 9. FIG. 9 graphically illustrates variation in
total fuel consumption for the MoS.sub.2 based nano suspension
lubricant, according to an example implementation. The y-axis of
the graph 900 illustrated in FIG. 9 depicts the total fuel
consumption and the x-axis depicts the time duration of the test.
The time duration is expressed in hours and the total fuel
consumption is expressed in Kg/hr. As may be observed from the
graph 900 and the Table 2.11, the fuel consumption has reduced with
the MoS.sub.2 based nano suspension lubricant as compared to the
lubricating fluid without having nano particles. Based on the
endurance test it may be concluded that the MoS.sub.2 based nano
suspension lubricant exhibits a reduction in the wear of the
components of the engine and improvement in the mileage of the
engine. Further, based on the stability test, tribological tests,
bench tests, and endurance tests, it may be concluded that for
optimal results MoS.sub.2 nano particles from about 0.05 weight %
to 0.1 weight % may mixed in the lubricating fluid.
Example 3
Tungsten Disulphide (WS.sub.2) Based Nano Suspension Lubricant
[0195] According to an example implementation of the present
subject matter, the nano suspension lubricant includes surface
modified tungsten disulphide nano particles from about 0.05 weight
% to 0.1 weight % dispersed in the lubricating fluid. The lubricant
fluid includes about 90% to 99% base oil, such as, petroleum
fractions, mineral oils, vegetable oils, synthetic oils, solvent
refined mineral oils, hydrocracked mineral oils, polyalphaolefins,
polyalkylglycols, synthetic esters, and the like. The lubricating
fluid also includes about 1% to 10% additives, such as,
antioxidants, detergents, and antiwear agents. The WS.sub.2 nano
particles are coated with Cetrimonium Bromide (CTAB) surfactant to
obtain surface modified WS.sub.2 nano particles. The surface
modified WS.sub.2 nano particles from about 0.05 weight % to 0.1
weight % are dispersed in the lubricating fluid by stirring for
about 1 hour in an ultra sound sonicator. The WS.sub.2 nano
particles used have a size less that about 100 nanometers. In an
example, SPAN 80 surfactant may be used for surface modification of
the WS.sub.2 nano particles.
[0196] Stability Test for WS.sub.2 Based Nano Suspension
Lubricant
[0197] Stability of the WS.sub.2 based nano suspension lubricant is
evaluated using a Dynamic Light Scattering (DLS) technique. The DLS
technique determines the size distribution profile of small
particles in suspension or polymers in a mixture. The stability of
any suspension is measured in terms of relative change in average
particle size of the dispersed particles in the suspension. In a
good suspension the size of the particles remain more or less same
over a period of time.
[0198] The stability of the suspension in terms of average particle
size is investigated over a period of 2 months. The variation of
the WS.sub.2 nano particles surface modified with CTAB is shown in
the following table.
TABLE-US-00026 TABLE 3.1 The average particle size of the surface
modified WS.sub.2 nano particles over a period of 60 days Average
particle size of surface modified WS.sub.2 nano particles Day
expressed in nm. 1.sup.st Day 214.4 15.sup.th Day 244.3 30.sup.th
Day 248.3 60.sup.th Day 255.32
[0199] As may be understood from the table 3.1, the average
particle size of the surface modified WS.sub.2 nano particles over
a period of 60 days did not have substantial change. This indicates
good steric repulsions between the surface modified WS.sub.2 nano
particles in the lubricating fluid and consequently better
stability. Test results are illustrated below for the WS.sub.2
based nano suspension lubricant including lubricating fluids having
different compositions for the base oil.
[0200] Tests for Physico-Chemical Properties
[0201] In an example implementation to analyze the physico-chemical
properties of the WS.sub.2 based nano suspension lubricant,
different tests such as Kinematic viscosity test, Total Acid Number
test, Total Base Number test, and copper strip corrosion test are
performed.
[0202] Kinematic Viscosity Test
[0203] Viscosity of the nano suspension lubricant is closely
related to its ability to reduce friction. Viscosity index is a
parameter that indicates the variation of viscosity with
temperature. The Viscosity index is calculated as per ASTM D 445
standard by measuring viscosity of the WS.sub.2 based nano
suspension lubricant at 40.degree. C. and 100.degree. C. A high
value (normally >90) of the viscosity index indicates that the
nano suspension lubricant has good lubricating properties.
TABLE-US-00027 TABLE 3.2 Viscosity index for the WS.sub.2 based
nano suspension lubricant with SM petrol engine oil (SAE 20 W 40)
as the lubricating fluid Lubricant used Viscosity index Petrol
engine oil SM grade >110 (SAE 20 W 40) + 0.05% surface modified
WS.sub.2 nano particles Petrol engine oil SM grade >110 (SAE 20
W 40) + 0.1% surface modified WS.sub.2 nano particles
TABLE-US-00028 TABLE 3.3 Viscosity index for the WS2 based nano
suspension lubricant with diesel engine oil CI 4 grade (SAE 20 W
40) as the lubricating fluid Lubricant used Viscosity index Diesel
engine oil CI 4 (SAE >110 15 W 40) + 0.05% surface modified
WS.sub.2 nano particles Diesel engine oil CI 4 (SAE >110 15 W
40) + 0.1% surface modified WS.sub.2 nano particles
[0204] Total Acid Number Test
[0205] As explained above, maintaining a low TAN value is essential
for lubricants to protect components of engines from acidic
corrosion. Generally, a low TAN value (<3) gives an indication
that the nano suspension lubricant is non-corrosive.
[0206] The table below illustrates the TAN values of the WS.sub.2
based nano suspension lubricant including surface modified WS.sub.2
nano particles dispersed in different lubricating fluids having
different base oil compositions.
TABLE-US-00029 TABLE 3.4 Total Acid number with WS.sub.2 based nano
suspension lubricant having petrol engine oil SM grade (SAE 20 W
40) as the lubricating fluid Lubricant used Total Acid number
Petrol engine oil SM grade (SAE 20 <2 W 40) Petrol engine oil SM
grade (SAE 20 <2 W 40) + 0.05% surface modified WS.sub.2 nano
particles Petrol engine oil SM grade (SAE 20 <2 W 40) + 0.1
surface modified WS.sub.2 nano particles
TABLE-US-00030 TABLE 3.5 Total Acid number with WS.sub.2 based nano
suspension lubricant having diesel engine oil CI4 grade (SAE 15 W
40) as the lubricating fluid Lubricant used Total Acid number
Diesel engine oil CI4 grade (SAE 15 <2.2 W 40) Diesel engine oil
CI4 grade (SAE 15 <2.2 W 40) + 0.05% surface modified WS.sub.2
nano particles Diesel engine oil CI4 grade (SAE 15 <2.2 W 40) +
0.1% surface modified WS.sub.2 nano particles
[0207] Thus, as may be understood from the tables above, the Total
Acid Number of the nano suspension lubricant dispersed with surface
modified WS.sub.2 nano particles does not result in substantial
change or deterioration of the total acid number of the nano
suspension lubricant and is suitable for use in the automotive
industry.
[0208] Total Base Number Test (TBN)
[0209] As explained earlier, the higher the TBN (typically >9),
the more effective the nano suspension lubricant is in suspending
wear-causing contaminants and reducing the corrosive effects of
acids over an extended period of time. The tables below illustrate
the TBN values of the WS.sub.2 based nano suspension lubricant
including surface modified WS.sub.2 nano particles dispersed in
different lubricating fluids having different base oil
compositions.
TABLE-US-00031 TABLE 3.6 Total Base number with the WS.sub.2 based
nano suspension lubricant having diesel engine oil CI4 grade (SAE
15 W 40) as the lubricating fluid Lubricant used Total Base number
Diesel engine oil >10 Diesel engine oil + 0.1% surface >10
modified WS.sub.2 nano particles with surfactant SPAN 80 Diesel
engine oil + 0.1% surface >10 modified WS.sub.2 nano particles
with surfactant CTAB
TABLE-US-00032 TABLE 3.7 Total Base number with WS.sub.2 based nano
suspension lubricant having petrol engine oil SM grade (SAE 20 W
40) as the lubricating fluid Lubricant used Total Base number
Petrol engine oil >6 Petrol engine oil + 0.1% surface modified
>6 WS.sub.2 nano particles with surfactant SPAN 80 Petrol engine
oil + 0.1% surface >6 modified WS.sub.2 nanoparticles with
surfactant CTAB
[0210] Copper Strip Corrosion Test
[0211] The Copper Strip Corrosion Test is carried out to assess the
relative degree of corrosiveness of a number of petroleum products,
including aviation fuels, automotive gasoline, lubricating oils and
other products. Hence, the copper strip corrosion test is performed
for the WS.sub.2 based nano suspension lubricant.
[0212] In these tests, the petrol engine oil of SM 4 grade is
selected as the lubricating oil. The lubricating oil mixed with
surface modified WS.sub.2 nano particles was tested for copper
strip corrosion test at 100.degree. C. for 3 hours and the tarnish
level of the copper strips were assessed against the ASTM Copper
Strip Corrosion Standard. The results are shown in the table
below.
TABLE-US-00033 TABLE 3.8 Copper strip corrosion test results for
the WS.sub.2 based nano suspension lubricant Lubricant used Copper
strip corrosion result Petrol engine oil of SM grade 1a Petrol
engine oil of SM grade + surface 1a modified WS.sub.2 nano
particles using CTAB as surfactant Petrol engine oil of SM grade +
surface 1b modified WS.sub.2 nano particles using SPAN 80 as
surfactant
[0213] Thus, it may concluded that there is no abnormal
deterioration of the physico-chemical properties of the WS.sub.2
based nano suspension lubricant. Further, it may be noted from the
table 3.8 that CTAB is suitable as a surfactant for surface
modification of the WS.sub.2 nano particles, at least for uses in
the automotive industry.
[0214] Further, to assess the tribological properties, such as
friction resistance, wear resistance, etc., of the nano suspension
lubricant, wear and friction tests are performed on the WS.sub.2
based nano suspension lubricant. The wear and friction tests are
conducted for the surface modified WS.sub.2 nano particles
dispersed in different lubricating fluids at different load
conditions.
[0215] The wear tests are conducted for each of petrol engine oil
and diesel engine oil as the lubricating fluid at 40 kgf load and
60 kgf load. The wear tests on gear oils of GL 4 grade are
conducted at 40 kgf and 80 kgf loads. Wear scar diameters (WSD) on
the stationary balls are measured using a Metallurgical
microscope.
[0216] FIGS. 10(a)-10(h) graphically illustrate the wear test
results for the WS.sub.2 based nano suspension lubricant with the
surface modified WS.sub.2 nano particle suspended in different
lubricating fluids, according to an example implementation. In the
graphs illustrated in the FIGS. 10(a)-10(h), the y-axis depicts the
wear scar diameter and the x-axis depicts different compositions of
the WS.sub.2 based nano suspension lubricant with different
lubricating fluids, such as diesel engine oil, petrol engine oil,
and gear oil. The wear scar diameter is represented in microns.
[0217] The graphs 1000(a)-1000(h) illustrate the wear test results
for the WS.sub.2 based nano suspension lubricant. It may be
concluded that based on the lubricating oil an optimum weight
percentage of the nano particles may be chosen for best
performance. As may be observed from the graphs, in general, the
optimum weight % of the surface modified WS.sub.2 nano particles
for best results lies between 0.05% to 0.1%.
[0218] Further, to determine the tribological properties of the
WS.sub.2 based nano suspension lubricant friction test as per ASTM
D 5183 standard have been performed. The friction tests have been
conducted to determine the coefficient of friction of the WS.sub.2
based nano suspension lubricant under the following prescribed test
conditions using ASTM 4 Ball wear test machine.
TABLE-US-00034 Temperature 75 .+-. 2.degree. C. Speed 600 RPM
Duration 10 min at each load starting from 10 kgf Load 98.1 N (10
kgf) per 10 min increment to a load that indicate incipient seizure
(sudden increase in friction force value over steady state) on the
friction trace
[0219] FIGS. 11(a)-11(h) graphically illustrates the friction test
results for the WS.sub.2 based nano suspension lubricant with the
surface modified WS.sub.2 nano particle suspended in different
lubricating fluids, according to an example implementation. It may
be noted from the graphs 1100(a)-1100(h) that the WS.sub.2 based
nano suspension lubricant has enhanced friction protection
capabilities.
[0220] Further, to determine the wear characteristics of the
WS.sub.2 based nano suspension lubricant, metallographic studies of
worn out metallic balls used in the wear test can be performed.
FIG. 12 graphically illustrates characterization of the worn out
balls on scanning electron microscope with X-ray diffraction
attachment for the WS.sub.2 based nano suspension lubricant,
according to an example implementation. The graph 1202 depicts the
deposition of tungsten and sulphur particles at peak 1203 on the
worn out balls when the lubricating fluid, such as gear oil of GL 4
grade mixed with 0.05 weight % of the surface modified WS.sub.2
nano particles is being used for lubrication. The graph 1204
depicts the deposition of tungsten and sulphur particles at peak
1205 on the worn out balls when the lubricating fluid, such as gear
oil GL 4 grade mixed with 0.10 weight % of the surface modified
WS.sub.2 nano particles is being used for lubrication.
[0221] Performance Test on Petrol Engine Test Rig
[0222] The performance test with lubricating oil is carried out on
the petrol engine test rig, as explained earlier. FIG. 13
graphically illustrates variations in brake thermal efficiency of
the WS.sub.2 based nano suspension lubricant in a petrol engine
rig, according to an example implementation. The graph 1300
illustrated in FIG. 13 depicts the variation of brake thermal
efficiency with brake power at 2500 RPM speed of the engine and the
graph 1302 illustrated in FIG. 13 illustrates the variation of
brake thermal efficiency with brake power at 4000 RPM speed of the
engine. In the graphs 1300 and 1302 the y-axes depicts the brake
thermal efficiency (.eta..sub.brake thermal) and the x-axes depicts
the brake power. The brake power is represented in watts.
[0223] From the graphs 1300 and 1302, an improvement in the brake
thermal efficiency at lower as well as higher speeds of the engine
is observed with the WS.sub.2 based nano suspension lubricant. The
WS.sub.2 based nano suspension lubricant shows higher efficiency
improvement at higher loads and higher speeds of the engine.
[0224] Performance Testing on Diesel Engine Test Rig
[0225] The performance test of the WS.sub.2 based nano suspension
lubricant with a diesel engine oil is carried out on the Diesel
engine test rig, as explained earlier. FIG. 14 graphically
illustrates variations in brake thermal efficiency of the WS.sub.2
based nano suspension lubricant in a diesel engine rig, according
to an example implementation. The graph 1400 illustrated in FIG. 14
depicts the variation of brake thermal efficiency with brake power
at 2500 RPM speed of the engine and the graph 1402 illustrated in
FIG. 8 depicts the variation of brake thermal efficiency with brake
power at 4000 RPM speed of the engine. In the graphs 1400 and 1402
the y-axis depicts the brake thermal efficiency (.eta..sub.brake
thermal) and the x-axis depicts the brake power. The brake power is
represented in watts. From the graphs of FIG. 14 it is evident that
the WS.sub.2 based nano suspension lubricant has an improved brake
thermal efficiency.
[0226] Endurance Test for Wear and Life of Engine with the WS.sub.2
Based Nano Suspension Lubricant
[0227] The wear performance of the WS.sub.2 based nano suspension
lubricant is tested by subjecting the engine lubricated with the
WS.sub.2 based nano suspension lubricant to 80 hour test under
cyclic loading on a test rig. The test conditions are same as for
the endurance test performed in example 2 on the WS.sub.2 based
nano suspension lubricant.
TABLE-US-00035 TABLE 3.9 Results of wear of the cylinder liner with
the WS.sub.2 based nano suspension lubricant at different positions
of the cylinder Cylinder liner wear in micrometer (.mu.m) petrol
engine oil + 0.1% Position from surface modified WS.sub.2 TDC in cm
petrol engine oil nano particles 2 5.0 4.00 4 6.5 3.50 4 7.5 3.00 8
7.55 4.50 Mean Wear in microns 6.64 3.75
[0228] Another parameter to be determined for determination of
endurance of the engine is the wear of the piston rings in the
engine. The wear of the piston rings are reported in terms of
weight loss of the piston rings. the test results for weight loss
in the piston rings are tabulated below.
TABLE-US-00036 TABLE 3.10 Results for weight loss of the piston
rings and gudgeon ring in 80 hr test Components petrol engine oil +
0.1% surface modified WS.sub.2 nano petrol engine oil particles
Piston rings. Serial Weight loss mg Weight loss mg Compression 1IP
2 1 ring 1 Compression 2IP 18 10 ring 1 Expanding ring E1 2 2 Oil
ring 1 1SR 7 3 Oil ring 2 2SR 5 1 Total weight loss, mg 34 19
Gudgeon pin wear, mg 11 5
[0229] It may be noted from the Table 3.10 that the nano suspension
lubricant having the WS.sub.2 nano particles dispersed therein have
substantially reduced the wear in the piston rings and the cylinder
liners of the engine. Thus, the WS.sub.2 based nano suspension
lubricant offers improved endurance to the engine.
[0230] Fuel Consumption Test
[0231] The fuel consumption is measured during the endurance test
at an interval of 2 hours to assess the fuel efficiency of the nano
suspension lubricant. The fuel consumption at an instant and total
fuel consumption were recorded and tabulated in the table given
below.
TABLE-US-00037 TABLE 3.11 Total fuel consumption rates for the
WS.sub.2 based nano suspension lubricant during the fuel
consumption test Total fuel consumed in Percentage Lubricant used
litres improvement Lubricating fluid (petrol engine oil) 93.300
Lubricating fluid + 0.1% WS.sub.2 82.970 11.072
[0232] The results tabulated in the Table 3.11 is plotted in the
graph 1500 of FIG. 15. FIG. 15 graphically illustrates the
variation in total fuel consumption for the WS.sub.2 based nano
suspension lubricant, according to an example implementation. As
may be observed from the graph 1500 and the Table 3.11, the fuel
consumption has reduced with the WS.sub.2 based nano suspension
lubricant as compared to the lubricating fluid without having nano
particles. Thus, the WS.sub.2 based nano suspension lubricant
provides improved mileage to automobiles.
[0233] Evaluation of EP Properties of the WS.sub.2 Based Nano
Suspension Lubricant Using ASTM D 2783 Standard
[0234] The EP test determines the load carrying properties of the
nano suspension lubricant. Generally, two parameters, such as
Load-wear index and Weld load are evaluated to make this
determination. Higher the value of the load wear index and weld
load for a lubricant, the lubricant may be understood to have
better EP properties.
[0235] The EP tests are carried out on the WS.sub.2 based nano
suspension lubricant having gear oils of GL4 grade of viscosity
grades of SAE 80 W 90 and EP 140 as the lubricant fluid. The
results of the EP test are tabulated below:
TABLE-US-00038 TABLE 3.12 Variations in EP properties for the
WS.sub.2 based nano suspension lubricant with gear oil of GL 4
grade of viscosity grade SAE 80 W 90 as the lubricating fluid load
wear weld Lubricant used index load Gear oil GL 4 (SAE 80W90) 55.17
250 Gear oil GL 4 (SAE 80W90) + 0.05% 60.94 315 WS.sub.2 surface
modified with CTAB Gear oil GL 4 (SAE 80W90) + 0.1% 60.32 315
WS.sub.2 surface modified with CTAB
[0236] FIGS. 16(a)-16(d) graphically illustrates the variation of
extreme pressure (EP) properties of the WS.sub.2 based nano
suspension lubricant, with the surface modified WS.sub.2 nano
particle suspended in different lubricating fluids, according to an
example implementation. The results of Table 3.12 are plotted in
the graphs 1600(a) and 1600(b) illustrated in FIGS. 16(a) and
16(b), respectively. From the graphs of FIGS. 16(a)-16(d), it may
be understood that the WS.sub.2 based nano suspension lubricant has
improved EP properties.
[0237] Other embodiments of the present subject matter will be
apparent from consideration of the present specification. It is
intended that the present specification and examples be considered
as illustrative only and as encompassing the equivalents
thereof.
* * * * *