U.S. patent application number 14/821099 was filed with the patent office on 2016-06-09 for lubricant additive.
This patent application is currently assigned to UES, INC.. The applicant listed for this patent is Amarendra K. Rai. Invention is credited to Amarendra K. Rai.
Application Number | 20160160148 14/821099 |
Document ID | / |
Family ID | 56093744 |
Filed Date | 2016-06-09 |
United States Patent
Application |
20160160148 |
Kind Code |
A1 |
Rai; Amarendra K. |
June 9, 2016 |
LUBRICANT ADDITIVE
Abstract
A lubricant formulation. The lubricant formulation includes a
polyol-based base lubricant, an ionic liquid, and an organic
nanoparticle. The ionic liquid is selected from the group
consisting of trihexyltetradecylphosphonium
bis(2-ethylhexyl)phosphate, trihexyl(tetradecyl)phosphonium
bis-2,4,4-(trimethylpentyl)phosphinate, and
trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide,
or a combination thereof. The organic nanoparticle has a median
particle size less than about 200 nm. The organic nanoparticle
forms about 0.01 to about 5% by weight of the lubricant
formulation. The ionic liquid forms about 0.5 to about 10% by
weight of the lubricant formulation.
Inventors: |
Rai; Amarendra K.;
(Beavercreek, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Rai; Amarendra K. |
Beavercreek |
OH |
US |
|
|
Assignee: |
UES, INC.
Dayton
OH
|
Family ID: |
56093744 |
Appl. No.: |
14/821099 |
Filed: |
August 7, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62037438 |
Aug 14, 2014 |
|
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Current U.S.
Class: |
508/116 ;
508/128 |
Current CPC
Class: |
C10N 2040/044 20200501;
C10M 171/00 20130101; C10M 107/20 20130101; C10M 137/12 20130101;
C10N 2030/06 20130101; C10M 2223/0603 20130101; C10N 2020/077
20200501; C10N 2040/04 20130101; C10M 125/02 20130101; C10M 141/10
20130101; C10N 2040/042 20200501; C10M 2201/041 20130101; C10M
2207/2835 20130101; C10M 169/04 20130101; C10N 2020/06
20130101 |
International
Class: |
C10M 141/10 20060101
C10M141/10; C10M 169/04 20060101 C10M169/04; C10M 137/12 20060101
C10M137/12; C10M 107/20 20060101 C10M107/20; C10M 125/02 20060101
C10M125/02 |
Goverment Interests
GOVERNMENT LICENSE RIGHTS
[0002] This invention was made with government support under
Contract No. W911 QX-13-C-0174. The government has certain rights
in the invention.
Claims
1. An additive composition comprising: an ionic liquid; and an
organic nanoparticle.
2. The additive composition of claim 1, wherein the ionic liquid is
halogen-free.
3. The additive composition of claim 2, wherein the ionic liquid is
a phosphonium-based ionic liquid.
4. The additive composition of claim 3, wherein the ionic liquid is
selected from the group consisting of trihexyltetradecylphosphonium
bis(2-ethylhexyl)phosphate, trihexyl(tetradecyl)phosphonium
bis-2,4,4-(trimethylpentyl)phosphinate, and
trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide,
and combinations thereof.
5. The additive composition of claim 1, wherein the organic
nanoparticle is graphene.
6. The additive composition of claim 1, wherein the organic
nanoparticle has a median particle size less than about 200 nm.
7. The additive composition of claim 1, wherein the organic
nanoparticle includes at least one of a nanopore and a
mesopore.
8. A lubricant formulation comprising: a base lubricant; an ionic
liquid; and an organic nanoparticle.
9. The lubricant formulation of claim 8, wherein the base lubricant
is a polyol-based lubricant.
10. The lubricant formulation of claim 8, wherein the ionic liquid
is halogen-free.
11. The lubricant formulation of claim 10, wherein the ionic liquid
is a phosphonium-based ionic liquid.
12. The lubricant formulation of claim 11, wherein the ionic liquid
is selected from the group consisting of
trihexyltetradecylphosphonium bis(2-ethylhexyl)phosphate,
trihexyl(tetradecyl)phosphonium
bis-2,4,4-(trimethylpentyl)phosphinate, and
trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide,
and combinations thereof.
13. The lubricant formulation of claim 8, wherein the organic
nanoparticle is graphene.
14. The lubricant formulation of claim 8, wherein the organic
nanoparticle has a median particle size less than about 200 nm.
15. The lubricant formulation of claim 8, wherein the organic
nanoparticle includes at least one of a nanopore and a
mesopore.
16. The lubricant formulation of claim 8, wherein the organic
nanoparticle comprises about 0.01-10% by weight of the lubricant
formulation.
17. The lubricant formulation of claim 16, wherein the organic
nanoparticle comprises about 0.01 to about 5% by weight of the
lubricant formulation.
18. The lubricant formulation of claim 8, wherein the ionic liquid
comprises about 0.5 to about 10% by weight of the lubricant
formulation.
19. The lubricant formulation of claim 8, wherein the ionic liquid
comprises about 3 to about 6% by weight of the lubricant
formulation.
20. A lubricant formulation comprising: a polyol-based base
lubricant; an ionic liquid selected from the group consisting of
trihexyltetradecylphosphonium bis(2-ethylhexyl)phosphate,
trihexyl(tetradecyl)phosphonium
bis-2,4,4-(trimethylpentyl)phosphinate, and
trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide,
or a combination thereof; and an organic nanoparticle having a
median particle size less than about 200 nm; wherein the organic
nanoparticle comprises about 0.01 to about 5% by weight of the
lubricant formulation; and wherein the ionic liquid comprises about
1 to about 15% by weight of the lubricant formulation.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Patent
Application No. 62/037,438 filed Aug. 14, 2014, the entirety of
which is incorporated by reference herein.
TECHNICAL FIELD
[0003] The present invention relates to lubricant additives and
formulations, and more particularly to lubricant additives and
formulations for use in connection with rotorcraft transmission and
gearbox systems, and other rotary platforms.
BACKGROUND
[0004] Metal parts in close tolerances and contacts are a design
feature of many electromechanical and mechanical devices.
Lubricants maintain viscosity and protect components more
effectively under the high shear stresses that these systems place
on metal parts. The benefits of a well-lubricated system include an
increase in the effective service life of the constituent parts of
the system and the system as a whole, as well as enhanced fuel
efficiency, which can lead to significant cost savings. In a
typical engine set-up, 10-15% of the energy is lost due to
friction.
[0005] Certain systems, such as rotorcraft transmission systems and
rotary platforms more generally, are frequently operated in extreme
conditions which require the use of a high quality lubricant
capable of carrying a high load. This is especially true in the
context of transmission and gearbox systems for military and
civilian rotorcraft, as the main gearbox is one of the most
vulnerable portions of the rotorcraft. This is true even if
redundant systems are employed to provide emergency lubrication
systems, which add additional weight, complexity, and a risk of
dormant failure. When such redundant systems fail, these failures
cause both a dangerous situation as well as widespread
inconvenience for both the operators of the rotorcraft as well as
those served by the rotorcraft, such as offshore workers. In some
countries, including the U.S., the use of a lubricant capable of
supporting an aircraft in safe flight for at least 30 minutes after
the crew has detected lubrication system failure or loss of
lubrication is required for use in certain contexts.
[0006] Accordingly, an improved lubrication system, deliverable
through conventional service channels is therefore desirable. Ionic
liquids have been known to enhance the lubricity of a
system/material, for example as disclosed in U.S. Pat. Nos.
8,318,644 and 7,754,664, and the article "Ionic Liquids in
Tribology" (Minami, Ichirio, Molecules 14, no. 6 (2009):
2286-2305), each of which is incorporated by reference herein in
its entirety. Due to the inherent polarity of ionic liquids, they
adsorb strongly on the metallic tribocontact surfaces leading to a
robust tribofilm when compared to conventional lubricants. However
ionic liquids have an intrinsically high cost. Also, the use of
some ionic liquids having halogens can also result in undesirable
corrosion of metal surfaces having specific compositions.
[0007] Metal nanoparticles have also emerged as an approach to
advanced development for enhanced lubrication and heat transfer
capability. For example, incorporating metal nanoparticles into the
tribofilm can enhance rolling friction between the contact
surfaces, thereby reducing wear.
SUMMARY
[0008] In one aspect, an additive composition is disclosed. The
additive composition includes an ionic liquid and an organic
nanoparticle.
[0009] In another aspect, a lubricant formulation is disclosed. The
lubricant formulation includes a base lubricant, an ionic liquid,
and an organic nanoparticle.
[0010] In yet another aspect, a lubricant formulation is disclosed.
The lubricant formulation includes a polyol-based base lubricant,
an ionic liquid, and an organic nanoparticle. The ionic liquid is
selected from the group consisting of trihexyltetradecylphosphonium
bis(2-ethylhexyl)phosphate, trihexyl(tetradecyl)phosphonium
bis-2,4,4-(trimethylpentyl)phosphinate, and
trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide,
or a combination thereof. The organic nanoparticle has a median
particle size less than about 200 nm. The organic nanoparticle
forms about 0.01 to about 5% by weight of the lubricant
formulation. The ionic liquid forms about 1 to about 10% by weight
of the lubricant formulation.
[0011] Other aspects of the disclosed additive composition and
lubricant formulation will become apparent from the following
description, the accompanying drawings and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The embodiments set forth in the drawings are illustrative
and exemplary in nature and not intended to limit the subject
matter defined by the claims. The following detailed description of
the illustrative embodiments can be understood when read in
conjunction with the following drawings.
[0013] FIG. 1 is a chart showing comparative friction coefficient
profiles for embodiments of a lubricant formulation.
DETAILED DESCRIPTION
[0014] For simplicity and illustrative purposes, the principles of
the present invention are described by referring to various
exemplary embodiments thereof. Although the preferred embodiments
of the invention are particularly disclosed herein, one of ordinary
skill in the art will readily recognize that the same principles
are equally applicable to and can be implemented in other systems,
and that any such variation would be within such modifications that
do not part from the scope of the present invention. Before
explaining the disclosed embodiments of the present invention in
detail, it is to be understood that the invention is not limited in
its application to the details of any particular arrangement shown,
since the invention is capable of other embodiments. The
terminology used herein is for the purpose of description and not
of limitation.
[0015] An additive composition for a base lubricant is disclosed
including one or more ionic liquids and one or more organic
nanoparticles. Lubricant formulations incorporating the disclosed
additive provide enhanced performance in terms of wear protection
of system parts, reduced coefficient of friction, lower electrical
resistance, and longer oil-out run time as compared to the
performance of the base lubricant alone, under identical operating
conditions.
[0016] The term "base lubricant," as used herein, may refer to an
unformulated lubricant or a fully-formulated lubricant with
additives added thereto, including but not limited to
commercially-available formulated and/or unformulated
lubricants.
[0017] The base lubricant may be any of a variety of base
lubricants known in the art, or combinations thereof, including but
not limited to base lubricants conventionally used in any of a
variety of applications, including lubrication of engines and/or
rotorcraft transmission and gearbox systems, such as natural or
synthetic oils. In one embodiment, the base lubricant may be a
polyol ester or a polyol-based lubricant including hindered polyol
esters and any of a variety of additives, and it may be a
commercially-available base lubricant approved for use under U.S.
military specification DOD-L-85734. For example, the base lubricant
may be AEROSHELL.RTM. Turbine Oil 555, which is commonly used in
current rotorcraft systems. Other non-limiting examples of base
lubricants include but are not limited to transmission oils such as
Herco A (polyol ester, unformulated) and MOBIL SHC.RTM. 626
(formulated) and internal combustion engine oils such as mineral
oil (unformulated) and MOBIL 1.TM. 5W-30 (formulated).
[0018] The ionic liquid of the additive composition may be any of a
variety of ionic liquids, or combinations thereof. The addition of
an ionic liquid to the base lubricant appears to facilitate rapid
formation of a protective tribocoating on metal surfaces of the
system incorporating the lubricant. In one embodiment, the ionic
liquid is a non-corrosive ionic liquid, such as a halogen-free
ionic liquid, to reduce wear on system parts. The halogen-free
nature of the ionic liquid reduces sensitivity for hydrolysis,
which in turn reduces the incidence of corrosion. Ionic liquids are
known in the art, and selection of a suitable ionic liquid may be
based on factors such as lubricity and the ability to protect
against corrosion. Under given test conditions gear steel (for
example, AISI 9310 alloy steel) with the ionic liquid may have a
coefficient of friction less than that of the base lubricant. In
one non-limiting example (ball-on-disc test, Hertzian stress 800
MPa), the ionic liquid is trihexyltetradecylphosphonium
bis(2-ethylhexyl)phosphate, which yields a coefficient of friction
of about 0.044 with AISI 9310 alloy steel, as compared to
AEROSHELL.RTM. 555, which yields a coefficient of friction of about
0.057 with AISI 9310 alloy steel.
[0019] Representative ionic liquids that may be used include
phosphonium-based ionic liquids such as
trihexyltetradecylphosphonium bis(2-ethylhexyl)phosphate,
trihexyl(tetradecyl)phosphonium
bis-2,4,4-(trimethylpentyl)phosphinate and
trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide.
One of ordinary skill will appreciate that other ionic liquids
known in the art, including non-corrosive ionic liquids, may be
incorporated into the additive composition alone or in combination
without departing from the scope of this disclosure. The additive
composition may be incorporated into the lubricant formulation such
that the ionic liquid is provided in the lubricant formulation in
an amount of about 0.01-15% by weight, or various embodiments,
about 0.01-1.0%, about 0.01-2.0%, about 0.01-3.0%, about 0.01-4.0%,
about 0.01-5.0%, about 0.01-6.0%, about 0.01-7.0%, about 0.01-8.0%,
about 0.01-9.0%, about 0.01-10.0%, about 0.5%-10.0%, about
1.0%-5.0%, about 1.0%-6.0%, about 1.0%-7.0%, about 1.0%-8.0%, about
1.0%-9.0%, about 1.0%-10.0%, about 1.0%-15.0%, about 2.0%-6.0%,
about 3.0%-6.0%, about 2.0-10.0% by weight, about 4.0-6.0%, about
1%, about 2%, about 3%, about 4% about 5%, about 6%, about 7%,
about 8%, about 9%, or about 10% by weight.
[0020] The organic nanoparticles of the additive composition may be
any of a variety of carbon-based or carbon-containing
nanoparticles, or combinations of multiple varieties of
nanoparticles, including but not limited to nanographene (including
nanographene platelets), graphene oxide, carbon, carbon nanotubes
(single, double, or multi-walled), carbon nanofibers, fullerenes,
nanodots, nanopowders, nano-diamond and the like, in any of a
variety of morphological configurations. Carbon nanoparticles are
less expensive than metal nanoparticles of metals such as copper,
silver, and gold, and carbon nanoparticles may be less toxic and
safer to handle than metal-based nanoparticles. The organic
nanoparticles may range in size from about 0.1 to 999 nm in median
particle size, and in one embodiment no greater than about 200 nm
in median particle size. The nanoparticles may include mesopores
and/or micropores, which may improve buoyancy of the nanoparticles
within the resultant lubricant formulation and prevent settling.
The additive composition may be incorporated into the lubrication
formulation such that the organic nanoparticles are provided in the
lubricant formulation in the amount of about 0.01-10% by weight, or
in various embodiments, about 0.01%, about 0.02%, about 0.03%,
about 0.04%, about 0.05%, about 0.06%, about 0.07%, about 0.08%,
about 0.09%, about 0.10%, about 0.01-0.03%, about 0.01-0.04%, about
0.01-0.05%, about 0.01-0.06%, about 0.01-0.07%, about 0.01-0.08%,
about 0.01-0.09%, about 0.01-0.10%, about 0.01-1.0%, about
0.01-2.0%, about 0.01-5.0%, about 0.05-0.5%, or about 0.1-1.0% by
weight.
[0021] The ranges disclosed herein with respect to the ionic liquid
content and the organic nanoparticle content of the additive
compositions may be interchangeably combined in any combination,
with any ionic liquid or organic nanoparticle disclosed herein. For
example, the additive composition of the lubricant formulation may,
in one embodiment, include about 1.0-8.0% by weight ionic liquid
(trihexyltetradecylphosphonium bis(2-ethylhexyl)phosphate) and
about 0.01-0.10% by weight organic nanoparticle (graphene
platelets), and in another embodiment, about 5% by weight ionic
liquid (trihexyl(tetradecyl)phosphonium
bis-2,4,4-(trimethylpentyl)phosphinate) and about 0.01-5% organic
nanoparticle (carbon nanotubes). Each permutation of the
embodiments of these ranges may be further used in combination with
any of the base lubricants described herein.
[0022] Without wishing to be bound by the theory, when the
lubrication formulation incorporating the additive composition is
utilized in an engine system, the organic nanoparticles aggregate
in wear grooves, patterns, and/or facets in the surfaces of the
parts being lubricated that may form during the operation of the
system or otherwise, thereby having a mending effect on the
pertinent surfaces as the nanoparticles accumulate. Accordingly,
the organic nanoparticles may provide lubrication and hence
additional protection to the system even without the presence of
the liquid lubricant components (i.e. the base lubricant and/or the
ionic liquid additive component), for example if the liquid
lubricant components are lost or removed for any reason, followed
by the loss of the ionic liquid-induced tribocoating. This improves
the ability of the lubricant formulation to provide protection to
system parts even in the event of a lubrication failure or the loss
of lubricant during operation.
[0023] The disclosed additive composition therefore provides a
number of benefits over state of the art lubricants because it
provides at least the dual benefits of rapidly establishing the
triboprotective coating on system surfaces via the ionic liquid,
and also synergistically filling in irregularities on the metal
surfaces to be lubricated via aggregation of the organic
nanoparticles. Together, these dual benefits greatly enhance the
ability of a system, such as a rotorcraft, to continue to operate
safely post-lubrication system failure or lubricant loss for a
significantly longer period of time than a base lubricant lacking
the ionic liquid and organic nanoparticle components of the
additive composition. Further, because the additive composition
provides these benefits as an additive to a relatively inexpensive
base lubricant, there is significant cost savings as compared to
formulating lubricants composed primarily of an expensive ionic
liquid base.
[0024] The additive composition enhances the function of
formulation used for both internal combustion engines and also
transmission lubrications, and is therefore suitable for a wide
variety of applications beyond rotorcraft transmission and gearbox
systems, such as use in bearing applications and/or other
tribomechanical systems that require lubrication.
[0025] In one non-limiting example, the additive composition
included carbon nanoparticles and the ionic liquid
trihexyltetradecylphosphonium bis(2-ethylhexyl)phosphate, which
were added to the base lubricant of AEROSHELL.RTM. 555 in the
amounts of 5.0% by weight ionic liquid, 0.1% by weight carbon
nanoparticle, and 94.9% by weight AEROSHELL.RTM. 555. A protocol
for an oil-out simulation was created on the Cameron-Plint
tribometer to test the effectiveness of this lubricant formulation.
For the first 5 minutes, the test was run at 20N load as a run-in
period in a fully flooded (2 ml of lubricant formulation)
condition. After 5 minutes, the load was increased to 250N
(Hertzian stress 700 MPa). After a 30 minute run with the 250N
load, an oil-out event was simulated by completely removing the
lubricant formulation. The test was continued under the "oil-out"
condition. For each run, the test was terminated when the friction
coefficient increased to 0.3, or the test duration (typically 300
minutes) ended. The tribological performance of the lubricant
formulation was compared with AEROSHELL.RTM. 555 (base line) under
such simulated oil-out conditions. The increase in run time after
oil-out test in the lubricant formulation was greater than 2108% of
the base line result.
[0026] In another non-limiting example, and with reference to FIG.
1, the additive composition included nano-graphene platelets and
the ionic liquid trihexyltetradecylphosphonium
bis(2-ethylhexyl)phosphate, which were added to the base lubricant
of AEROSHELL.RTM. 555 in the amounts of 1%, 3%, and 5.0% by weight
ionic liquid, 0.02% by weight graphene, and 98.98%, 96.98% and
94.98% by weight AEROSHELL.RTM. 555. A protocol for the oil-out
simulation was created on the Cameron-Plint tribometer to test the
effectiveness of these lubricant formulations. In each case, for
the first 5 minutes, the test was run at 20N load as a run-in
period in a fully flooded (1 ml of lubricant formulation)
condition. After 5 minutes the load was increased to 250N (Hertzian
stress 700 MPa). To create the oil-out event, the lubricant was
completely removed after a 60 minute run with the 250N load, and
the test was continued under the "oil-out" condition. In FIG. 1,
the "oil-out" time is represented by the hash mark at 60 minutes on
the x-axis. The test was terminated when the friction coefficient
increased to 0.3, or the test duration (typically 300 minutes)
ended. As shown in FIG. 1, the friction coefficient of certain
lubricant formulations rises sharply (>0.3) after a certain
amount of time in an oil-out condition. The tribological
performances of the three different lubricant formulations were
compared with AEROSHELL.RTM. 555 (base line) under such simulated
oil-out conditions. The results are detailed in Table 1, below:
TABLE-US-00001 TABLE 1 Average Increase in Run Friction Average
Wear Time from Oil-Out Until Time After Oil- Lubricant Formulation
Coefficient Reduction % Friction Coefficient >0.3 Out, %
AEROSHELL .RTM. 555 (baseline) 0.12 -- 12.65 minutes -- AEROSHELL
.RTM. 555, with 1% 0.13 3% 25.55 minutes 102% ionic liquid and
0.02% organic nanoparticle AEROSHELL .RTM. 555, with 3% 0.12 -32%
143.11 minutes 1031% ionic liquid and 0.02% organic nanoparticle
AEROSHELL .RTM. 555, with 5% 0.11 -35% >304.67 minutes >2308%
ionic liquid and 0.02% organic nanoparticle
[0027] As shown in Table 1, the 1% ionic liquid formulation
provided similar results to the baseline in terms of lubricity and
wear, but more than doubled the effective run time of the engine
after lubricant removal as compared to the baseline test. Each of
the 3% and 5% ionic liquid formulations provided both significant
wear reduction and also significant improvements in run time--at
least about 10 to 25 times the baseline without the additive
composition.
[0028] The effectiveness of carbon nanoparticles to reduce wear was
also tested. Under fully-flooded conditions, about 35% reduction of
wear was observed for a blend of AEROSHELL.RTM. 555+0.1% carbon
nano-particle as compared to baseline of AEROSHELL.RTM. 555, alone,
under the same conditions.
[0029] While the invention has been described with reference to
certain exemplary embodiments thereof, those skilled in the art may
make various modifications to the described embodiments of the
invention without departing from the scope of the invention. The
terms and descriptions used herein are set forth by way of
illustration only and not meant as limitations. In particular,
although the present invention has been described by way of
examples, a variety of compositions and processes would practice
the inventive concepts described herein. Although the invention has
been described and disclosed in various terms and certain
embodiments, the scope of the invention is not intended to be, nor
should it be deemed to be, limited thereby and such other
modifications or embodiments as may be suggested by the teachings
herein are particularly reserved, especially as they fall within
the breadth and scope of the claims which are to be appended. Those
skilled in the art will recognize that these and other variations
are possible within the scope of the invention as defined in the
claims and their equivalents.
* * * * *