U.S. patent application number 10/426788 was filed with the patent office on 2003-11-20 for process for lubrication-treating aluminum or aluminum alloy material.
Invention is credited to Kawagoshi, Ryosuke, Sumiya, Hiroshi, Yoshida, Masayuki.
Application Number | 20030213698 10/426788 |
Document ID | / |
Family ID | 29397453 |
Filed Date | 2003-11-20 |
United States Patent
Application |
20030213698 |
Kind Code |
A1 |
Kawagoshi, Ryosuke ; et
al. |
November 20, 2003 |
Process for lubrication-treating aluminum or aluminum alloy
material
Abstract
A lubrication-treating process for an Al or Al alloy material is
carried out by cleaning the material; applying an anodic oxidation
to the cleaned material surface to form a 3 to 30 .mu.m thick anode
oxidation coating; and forming a lubrication coating including a
polyester resin (30 to 70 mass parts), a particulate PTFE (30 to 70
mass parts) and ceramic (alumina) particles (0.5 to 5 mass parts),
and 2 to 20 .mu.m thick, to thereby impart excellent resistances to
adhesion and seizure, and a low friction, to the Al or Al alloy
material at a low cost and with no or a very low pollution of the
environment.
Inventors: |
Kawagoshi, Ryosuke; (Tokyo,
JP) ; Yoshida, Masayuki; (Tokyo, JP) ; Sumiya,
Hiroshi; (Hekinan-City, JP) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
1100 N GLEBE ROAD
8TH FLOOR
ARLINGTON
VA
22201-4714
US
|
Family ID: |
29397453 |
Appl. No.: |
10/426788 |
Filed: |
May 1, 2003 |
Current U.S.
Class: |
205/201 |
Current CPC
Class: |
C23C 28/00 20130101;
C25D 11/18 20130101 |
Class at
Publication: |
205/201 |
International
Class: |
C25D 011/18 |
Foreign Application Data
Date |
Code |
Application Number |
May 9, 2002 |
JP |
2002-134341 |
Claims
1. A process for lubrication-treating an aluminum or aluminum alloy
material, comprising: cleaning a surface of the aluminum or
aluminum alloy material; applying an anodic oxidation treatment to
the cleaned surface of the aluminum or aluminum alloy material, to
form an anodic oxidation coating layer having a thickness of 3 to
30 .mu.m on the wear-resistant material surface; and forming a
lubrication coating layer comprising a polyester resin, a
particulate polytetrafluoroethylene and ceramic particles and
having a thickness of 2 to 20 .mu.m on the anodic oxidation coating
layer.
2. The lubrication-treating process for an aluminum or aluminum
alloy material as claimed in claim 1, wherein the anodic oxidation
treatment is carried out in a sulfuric acid bath or an oxalic acid
bath, at a treatment temperature of 0 to 30.degree. C. at an
current density of 0.5 to 4 A/dm.sup.2.
3. The lubrication-treating process for an aluminum or aluminum
alloy material as claimed in claim 1, wherein the lubrication
coating layer is formed by coating a coating liquid comprising a
polyester resin, a particulate polytetrafluoroethylene and ceramic
particles on the anodic oxidation coating layer, and then baking
the coated coating liquid layer at a temperature of 100 to
250.degree. C. for 1 to 20 minutes.
4. The lubrication-treating process for an aluminum or aluminum
alloy material as claimed in claim 1, wherein the polyester resin
(A), the particulate polytetrafluoroethylene (B) and the ceramic
particles (C) in the lubrication coating layer are present in the
mass contents in the ranges of (A): 30 to 70 parts, (B): 30 to 70
parts and (C): 0.5 to 5 parts, per 100 parts of the total
(A)+(B)+(C).
5. The lubrication-treating process for an aluminum or aluminum
alloy material as claimed in claim 1, wherein the ceramic particles
are alumina particle having an average particle size of 0.01 to 0.2
.mu.m.
6. The lubrication-treating process for aluminum or an aluminum
alloy material as claimed in claim 1, wherein the aluminum or
aluminum alloy material is a sliding material.
Description
BACKGROUND OF INVENTION
[0001] (1) Field of the Invention
[0002] The present invention relates to a process for
lubrication-treating an aluminum or aluminum alloy material. More
particularly, the present invention relates to a process for
lubrication-treating aluminum or an aluminum alloy material such
as, for example, an aluminum or aluminum alloy sliding material to
form a wear-resistant composite coating on the surface of the
material. The process of the present invention is applied to
productions of high wear-resistant sliding materials, for example,
pistons and scrolls for compressors of air conditioners.
[0003] (2) Description of the Related Art
[0004] Generally, sliding materials are required to have a low
friction property to prevent an energy transfer loss. Also, when a
load is applied to the sliding material, an important property of
the sliding material is high load-resistance to prevent a seizure
of the sliding material under a high face pressure. Also, from an
industrial viewpoint, it is strongly required that the
above-mentioned properties of the sliding materials can be
maintained for a long time that the sliding material have a high
durability (a high wear resistance), and that they can be produced
at low cost. As a method of forming sliding coatings for the
sliding materials made of aluminum or an aluminum alloy, a hard
anodic oxidation treatment method is a well-known practice. The
resultant coatings of the anodic oxidation treatment, per se, do
not cause the friction coefficients of the sliding material
surfaces to decrease. However, the anodic oxidation coatings cause
the resultant sliding material surface to exhibit an enhanced wear
resistance and have a large number of pores which causes the
sliding material surface to exhibit an enhanced oil-holding
property and thus an improved surface lubrication property.
[0005] The seizure phenomenon is caused by contacting the same type
of metals with each other. To prevent the seizure, various methods
in which the surfaces contacting each other are plated with
metallic materials different from each other have been carried out
as well-known practices. For example, Japanese Examined Patent
Publications No. 56-18080 and No. 59-9160 disclose plating of the
sliding material surfaces with tin, iron and nickel materials. In
tin-plating, the plated tin per se serves as a solid lubrication
material and can reduce the friction coefficient of the sliding
material surface. However, a plated tin layer is soft and thus
exhibits a poor durability (a poor wear resistance). Also, in
general, there are problems that materials having a complicated
form and surface are difficult to uniformly plate and the plating
cost is generally high.
[0006] As an industrially low cost surface-treatment, a chemical
conversion treatment is known. As a chemical conversion treatment,
for the aluminum or aluminum alloy material, for a sliding material
with a lubrication coating, Japanese Unexamined Patent Publication
No. 11-193,478 discloses a method in which the aluminum or aluminum
alloy material is immersed in a treatment liquid containing a
fluorine compound and ammonium silicofluoride and treated at a
temperature in the range of from 70 to 100.degree. C. The Japanese
Publication reports that, as a result of the treatment, a coating
layer comprising an AlOH--F compound and/or a NH.sub.4MgAlF.sub.6
compound is formed. However, in fact, the resultant coating layer,
per se, does not cause the friction coefficient of the treated
material surface to decrease. Also, this treatment is
disadvantageous in that since the treatment liquid contains a large
amount of a fluorine compound, a load for purifying the waste water
from the treatment is high and thus a problem of the preservation
of the global environment occurs.
[0007] As a method of overcoating a lubricating agent on an anodic
oxidation layer, for example, Japanese Examined Patent Publication
No. 52-39,059 discloses a method in which an anodic oxidation
coating is formed on an aluminum or aluminum alloy material, and
then the resultant material is immersed in a solution of
polytetrafluoroethylene (PTFE) to impregnate the aluminum or
aluminum alloy material with the PTFE solution,. Also, Japanese
Unexamined Patent Publication No. 5-51,794 discloses a method in
which fine particles of polytetrafluoroethylene are
electrochemically or chemically absorbed on a surface of a hard
anodic oxidation coating formed on an aluminum or aluminum alloy
sliding material, the absorbed particle layer is dried, and the
dried particle layer surface is rubbed with a counterpart material
of the sliding material, to form a lubrication coated layer. In
each of the above-mentioned methods, PTFE is contained and held in
fine pores formed in the anodic oxidation coating layer. In these
methods, however, the close adhesive property of PTFE to the anodic
oxidation coating layer formed on the aluminum or an aluminum
material is low, and thus the PTFE layers formed by the
above-mentioned methods are unsatisfactorily close-bonded to the
anodic oxidation layer on the aluminum or aluminum alloy material.
The overcoated PTFE layer contributes to decreasing the friction
coefficient of the anodic oxidation layer. However, the PTFE layer
per se is soft and easily worn and thus a problem that the PTFE
layer is unsatisfactory in durability occurs.
[0008] For the purpose of decreasing the friction coefficient of
the sliding material, usually, a lubricating paint is used. In
practice, the lubricating paint contains a polyamideimide resin, as
a base material, and a solid lubricating agent such as molybdenum
disulfide, graphite and/or polytetrafluoroethylene (PTFE), as a
pigment. In this lubricating paint, the polyamideimide resin serves
as a binder and, thus, the lubrication paint is closely adhered to
the anodic oxidation layer on the aluminum or aluminum alloy
material. In this treatment, usually, a diluted lubrication paint
with an organic solvent is sprayed onto the anodic oxidation layer
on the aluminum or aluminum alloy material and then stored. This
method causes a problem that a harmful vapor of the organic solvent
is diffused into the air atmosphere. To solve the problem for the
purpose of keeping the global environment clean, a development of a
new lubricating means using no organic solvent is strongly
desired.
SUMMARY OF THE INVENTION
[0009] An object of the present invention is to provide a process
for lubrication-treating an aluminum or aluminum alloy material to
form a coating having an excellent wear resistance, a decreased
friction coefficient and a superior sliding property, on a surface
of the aluminum or aluminum alloy material, with a low cost and
with a low load on prevention of environmental pollution.
[0010] The above-mentioned object can be attained by the process of
the present invention.
[0011] The process of the present invention for
lubrication-treating an aluminum or aluminum alloy material,
comprises:
[0012] cleaning a surface of an aluminum or aluminum alloy
material;
[0013] applying an anodic oxidation treatment to the cleaned
surface of the aluminum or aluminum alloy material, to form an
anodic oxidation coating layer having a thickness of 3 to 30 .mu.m
on the wear-resistant material surface; and
[0014] forming a lubrication coating layer comprising a polyester
resin, a particulate polytetrafluoroethylene and ceramic particles
and having a thickness of 2 to 20 .mu.m on the anodic oxidation
coating layer.
[0015] In the lubrication-treating process, of the present
invention, for an aluminum or aluminum alloy material, the anodic
oxidation treatment is preferably carried out in a sulfuric acid
bath or an oxalic acid bath, at a treatment temperature of 0 to
30.degree. C. at an current density of 0.5 to 4 A/dm.sup.2.
[0016] In the lubrication-treating process of the present invention
for an aluminum or aluminum alloy material, the lubrication coating
layer is preferably formed by coating a coating liquid comprising a
polyester resin, a polytetrafluoroethylene and ceramic particles on
the anodic oxidation coating layer, and then baking the coated
coating liquid layer at a temperature of 100 to 250.degree. C. for
1 to 20 minutes.
[0017] In the lubrication-treating process of the present invention
for an aluminum or aluminum alloy material, the polyester resin
(A), the particulate polytetrafluoroethylene (B) and the ceramic
particles (C) in the lubrication coating layer are preferably
present in the mass contents in the ranges of (A): 30 to 70 parts,
(B): 30 to 70 parts and (C): 0.5 to 5 parts, per 100 parts of the
total (A)+(B)+(C).
[0018] In the lubrication-treating process of the present invention
for an aluminum or aluminum alloy material, the ceramic particles
are preferably alumina particle having an average particle size of
0.01 to 0.2 .mu.m.
[0019] In the lubrication-treating process of the present invention
for an aluminum or aluminum alloy material, the aluminum or
aluminum alloy material is preferably a sliding material.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] The metallic materials to which the process of the present
invention is applied are aluminum and aluminum alloy materials.
[0021] In the process of the present invention, first, a surface of
the aluminum or aluminum alloy material is cleaned. The purpose of
cleaning is to eliminate oiling materials (for example, cutting
oils) applied to the material surface during the production of the
aluminum or aluminum alloy material and soil on the material
surface. There is no limitation to the types of the cleaning
procedures. In view point of keeping the global environment clean,
organic solvent-containing cleaning materials are not desirable for
the process of the present invention. Preferably, an aqueous
alkali-containing cleaning agents are used. The surface-cleaned
aluminum or aluminum alloy material is subjected to an anodic
oxidation step in accordance with the process of the present
invention.
[0022] In the process of the present invention, the thickness of
the anodic oxidation coating is controlled to 3 to 30 .mu.m,
preferably 10 to 20 .mu.m. The anodic oxidation coating serves to
hold a lubrication coating thereon and to enhance the wear
resistance and the resistance to seizure of the resultant
lubrication-treated aluminum or aluminum alloy material. When the
aluminum or aluminum alloy material is subjected to a sliding
operation, a considerable pressure may be locally applied to the
sliding material. The anodic oxidation coating which is a
pressure-resistant layer prevents direct contact of the aluminum or
aluminum alloy sliding material with a metallic material on which
the sliding material slides and a seizure of the sliding material.
If the thickness of the anodic oxidation coating is less than 3
.mu.m, the resultant lubrication treated material exhibits an
insufficient wear resistance. Also, if the thickness of the anodic
oxidation coating is more than 30 .mu.m, while the performance of
the resultant material is saturated, the treatment cost is too
high, and thus an economical disadvantage occurs.
[0023] In the formation of the anodic oxidation coating in the
process of the present invention, a conventional sulfuric acid
anodic oxidation bath or oxalic acid bath may be used. When the
sulfuric acid bath is employed, preferably, the anodic oxidation
procedure is carried out at a sulfuric acid concentration of 10 to
20% by mass, at a treatment temperature of 10 to 20.degree. C. at a
current density of 0.5 to 1.5 A/dm.sup.2. When the oxalic acid bath
is employed, the anodic oxidation procedure is preferably carried
out at an oxalic acid concentration of 2 to 5% by mass at a
treatment temperature of 25 to 30.degree. C. at a current density
of 2 to 3A/cm.sup.2.
[0024] In the process of the present invention, the lubrication
coating is formed on the front surface side of the aluminum or
aluminum alloy material. A main purpose of the lubricating coating
is to decrease friction between the aluminum or aluminum alloy
material and a metallic material on which the aluminum or aluminum
alloy material slides during a sliding operation. In the process of
the present invention, the thickness of the lubrication coating is
controlled in the range of from 2 to 20 .mu.m, preferably from 6 to
14 .mu.m: If the thickness of the lubrication coating is less than
2 .mu.m, the resultant layer exhibits an insufficient
friction-reducing effect and thus an unsatisfactory sliding
property. If the thickness of the lubrication coating is more than
20 .mu.m the friction-reducing effect is saturated and the coating
cost becomes high, and thus an economical disadvantage occurs.
[0025] The material for forming the lubrication coating comprises,
as essential components, a polyester resin, a
polytetrafluoroethylene and ceramic particles, the polyester resin
serves as a binder to hold and bind the another components and to
form a firm coating. For the purpose of imparting a high mechanical
strength to the lubrication coating during the sliding operation,
the lubrication coating preferably contains a polyester resin
having a high mechanical strength. Also, when the sliding material
is subjected to a sliding operation, the lubrication coating is
brought into contact with a lubrication oil. In the case where the
sliding material is used in a compressor for an air conditioner,
the sliding circumstances contains a cooling medium (fluorocarbon
compounds, flon), in addition to the lubrication oil. Therefore,
the lubrication coating must be stable in the medium. As a result
of research on binder resins having a high resistance to the
lubrication oils and the fluorocarbon compounds, it was confirmed
that the polyester resins are most suitable for this use. The
particulate polytetrafluoroethylene is contained as a
friction-reducing agent in the lubrication coating.
[0026] The particulate polytetrafluroethylene preferably has an
average particle size of 0.05 to 30 .mu.m, more preferably, of 0.5
to 5 .mu.m.
[0027] Further, the ceramic particles are used to enhance the
resistance to seizure of the lubrication coating. When a seizure
occurs on the lubrication treated aluminum or aluminum alloy
sliding material produced by the process of the present invention,
the lubrication coating is destroyed and then the anodic oxidation
coating is destroyed by a metallic material on which the sliding
material slides, to such an extent that the aluminum or aluminum
alloy material comes into dry contact with the metallic material.
Thus, the total resistance of the aluminum or aluminum alloy
sliding material to the seizure can be enhanced by enhancing the
seizure resistance of the lubrication coating and thus the total
durability of the lubrication-treated aluminum or aluminum alloy
sliding material can be improved.
[0028] In a preferable method of forming the lubrication coating in
accordance with the process of the present invention, from the view
point of keeping the global environment clean, the lubrication
coating is formed from an aqueous lubrication agent. Particularly,
after an anodic oxidation coating is formed, an aqueous treatment
liquid containing a polyester resin, polytetrafluoroethylene
particles and ceramic particles dispersed in an aqueous medium is
coated on the anodic oxidation coating and then, the resultant
aqueous treatment liquid layer is baked at a temperature of 100 to
250.degree. C., more preferably 160 to 200.degree. C. for a time of
1 to 20 minutes, more preferably 5 to 15 minutes.
[0029] The thickness of the lubrication coating can be controlled
by controlling the coating amount of the aqueous treatment liquid.
If the baking temperature is lower than 100.degree. C., an
undesirable long time may be necessary to complete the baking
procedure. Also, if the baking temperature is higher than
250.degree. C., the polyester resin may be undesirably
deteriorated. If the baking time is less than one minute, the
baking procedure may not be sufficiently completed. If the baking
time is more than 20 minutes, the baking effect may be saturated
and the productivity of the target product may be reduced. To
enhance the drying effect in the lubrication coating-forming
procedure, a pre-heat treatment of the anodic oxidation-treated
sliding material to a temperature of 80 to 12.degree. C. may be
effectual.
[0030] The proportions of the contents of the components contained
in the lubrication coating to each other can be controlled by
controlling the concentrations of the components contained in the
aqueous-treatment liquid. In the process of the present invention,
the polyester resin (A) the particulate polytetrafluoroethylene (B)
and the ceramic particles (C) are preferably present in the mass
contents in the ranges of (A): 30 to 70 parts, preferably 40 to 60
parts, (B): 30 to 70 parts, preferably 40 to 60 parts and (C): 0.5
to 5 parts, preferably 1 to 3 parts, per 100 parts of the total
(sum) of (A), (B) and (C).
[0031] If the content of the polyester resin (A) is less than 30
parts by mass on the basis of (A)+(B)+(C)=100 parts by mass, the
binding effect of the polyester resin (A) in the lubrication
coating may be insufficient and, thus, a firm lubrication coating
may not be formed. Also, if the content of the polyester resin (A)
is more than 70 parts per 100 parts of the total (A)+(B)+(C), the
content of the particulate polytetrafluoroethylene (B) becomes too
low, and thus the resultant coating may exhibit an insufficient
lubrication effect.
[0032] If the content of the particulate polytetrafluoroethylene is
less than 30 parts per 100 parts of the total (A)+(B)+(C), the
resultant coating may exhibit an insufficient lubrication effect.
Also, if the content of the particulate polytetrafluoroethylene is
more than 70 parts per 100 parts of the total (A)+(B)+(C), the
resultant lubrication coating contains polyester resin in an
insufficient content, and thus the binding effect of the polyester
resin may become insufficient, and the resultant lubrication
coating may exhibit an insufficient mechanical strength. Further,
if the content of the ceramic particle is less than 0.5 parts per
100 parts of the total (A)+(B)+(C), the resistance to seizure of
the resultant lubrication coating may be insufficient, and if the
content of the ceramic particles is more than 5 parts, the
resultant lubrication coating may have an insufficient continuity,
and thus may exhibit an insufficient mechanical strength.
[0033] The ceramic particles usable for the process of the present
invention are preferably selected from alumina particles having an
average particle size of 0.01 to 0.2 .mu.m, more preferably 0.05 to
0.01 .mu.m. If the particle size is less than 0.01 .mu.m, the
particles are too fine and the resultant lubrication coating may
exhibit an insufficient seizure resistance. Also, if the particle
size is more than 0.2 .mu.m, the resultant particles may easily
agglomerate with each other and, as a result, the resultant
lubrication coating may have an insufficient continuity and
undesirable local adhesions of the lubrication coating may
occur.
[0034] The ceramic particles usable for the present invention may
be selected from silicon dioxide, zirconium oxide and/or titanium
dioxide. These ceramic particles may be used in mixture with
alumina particles.
EXAMPLES
[0035] The present invention will be further illustrated by the
following examples. Also, comparative examples will be shown for
the purpose of illustrating the advantages and effects of the
present invention in comparison with the comparative examples.
[0036] The aluminum or aluminum alloy materials, treatment
procedures for the materials, the measurements of the thickness of
coatings and evaluation of the resultant products of the examples
and comparative examples were as shown below.
[0037] (1) Starting Material
[0038] Type of material: ADC10
[0039] Form and dimensions: plate (40 mm.times.40 mm.times.1.5 mm
(thickness))
[0040] (2) Treatment Procedure
[0041] The aluminum alloy material is immersed in a 2% aqueous
solution of a cleaning agent (trademark: FINE CLEANER 315, made by
NIHON PARKERIZING K.K.) at a temperature of 60.degree. C. for 3
minutes; withdrawn from the cleaning solution; and rinsed with
water, to make the material clean. The cleaned aluminum alloy
material was subjected to an anodic oxidation treatment under the
conditions shown in each of the examples and comparative examples;
the anodic oxidation-treated aluminum alloy material is rinsed with
tap water for 30 seconds and dried at a temperature of 100.degree.
C. for 5 minutes. The surface of the resultant anodic oxidation
coating layer was coated with the aqueous lubrication liquid having
the composition shown in each of the examples and comparative
examples, by a spray coating procedure using an air spray gun, and
the coated lubrication liquid layer was dried and baked under the
conditions shown in each of the examples and comparative
examples.
[0042] (3) Measurement of Thickness of Coatings
[0043] The thickness of each coating formed on the aluminum alloy
material was measured in .mu.m.
[0044] (4) Evaluation
[0045] (a) Adhesion test
[0046] For the adhesion test, a lubrication tester (trademark:
TRYVOGUIER HEIDON-14DR, made by SHINTOKAGAKU K.K.) was
employed.
[0047] A specimen of a lubrication-treated aluminum alloy material
was brought into contact with a non-lubrication treated speed ball
(SUJ2, diameter: 5 mm); and the specimen and the ball were rubbed
with each other under a load of 10N at a rubbing speed of 0.1 m/sec
at a rubbing amplitude of 10 mm. The rubbing procedure was carried
out in two different ways, in one of which two ways, the rubbing
faces of the specimen and the ball were coated with a lubrication
oil (trademark: ND Oil 8, made by K.K. DENSO), and in the other one
of which, no lubrication oil was applied. The total rubbing
distance at which the specimen was adhered to the ball and the
friction coefficient between the specimen and the ball were
determined and evaluated. The longer the determined total rubbing
distance, the higher the lubrication property. In the case of no
lubrication oil, when the total rubbing distance was 20 m or more,
or in the case using the lubrication oil, when the total rubbing
distance was 400 m or more, the specimen was evaluated as
satisfactory (good) in the lubrication property. Also, the friction
coefficient must be as low as possible. Usually, the friction
coefficient of the specimen is evaluated as satisfactory
(good).
[0048] (b) Seizure Test
[0049] For seizure test, a friction and wear tester (model:
EFM-III-E, made by TOYO BALDWIN) was employed.
[0050] A treated specimen to be tested was brought into contact
with a non-treated aluminum collar (ADC10, an inside diameter: 23
mm, an outside diameter: 25 mm), the sliding faces of the specimen
and collar were coated with a lubrication oil; and then the
specimen and collar were rubbed against each other under a load of
50N at a rubbing speed of 2 m/second. The load was increased by 50N
each 2 minutes after, and the load under which a seizure of the
specimen with the collar occurred was determined. The higher the
seizure-generating load, the higher the seizure resistance of the
specimen.
[0051] When the seizure-generating load was 800N or more, the
specimen was evaluated as satisfactory (good) in the seizure
resistance.
Example 1
[0052] The aluminum alloy material for a sliding material as
mentioned above was subjected to the following procedures under the
conditions shown below.
[0053] Anodic Oxidation Coating-Forming Conditions
1 Treatment bath: Sulfuric acid 18% by mass Treatment temperature:
15.degree. C. Current density: 1 A/dm.sup.2 Treatment time: 60
minutes Thickness of coating: 20 .mu.m
[0054] Lubrication Coating-Forming Conditions
[0055] Composition
2 Polyester resin: 50% by mass Particulate PTFE: 48% by mass
Ceramic particles: 2% by mass (Alumina particles having an average
particle size of 0.1 .mu.m) Baking temperature: 180.degree. C.
Baking time: 10 minutes Thickness of coating: 10 .mu.m
[0056] The test results are shown in Table 1.
Example 2
[0057] The aluminum alloy material for a sliding material was
subjected to the following procedures under the conditions shown
below.
[0058] Anodic Oxidation Coating-Forming Conditions
3 Treatment bath: Sulfuric acid 18% by mass Treatment temperature:
15.degree. C. Current density: 1 A/dm.sup.2 Treatment time: 75
minutes Thickness of coating: 25 .mu.m
[0059] Lubrication Coating-Forming Conditions
[0060] Composition
4 Polyester resin: 30% by mass Particulate PTFE: 66% by mass
Ceramic particles: 4% by mass (Alumina particles having an average
particle size of 0.04 .mu.m) Baking temperature: 220.degree. C.
Baking time: 5 minutes Thickness of coating: 6 .mu.m
[0061] The test results are shown in Table 1.
Example 3
[0062] The aluminum alloy material for a sliding material was
subjected to the following procedures under the conditions shown
below.
[0063] Anodic Oxidation Coating-Forming Conditions
5 Treatment bath: Oxalic acid 4% by mass Treatment temperature:
28.degree. C. Current density: 2.5 A/dm.sup.2 Treatment time: 40
minutes Thickness of coating: 5 .mu.m
[0064] Lubrication Coating-Forming Conditions
[0065] Composition
6 Polyester resin: 68% by mass Particulate PTFE: 30% by mass
Ceramic particles: 2% by mass (Alumina particles having an average
particle size of 0.05 .mu.m) Baking temperature: 240.degree. C.
Baking time: 3 minutes Thickness of coating: 20 .mu.m
[0066] The test results are shown in Table 1.
Example 4
[0067] The aluminum alloy material for a sliding material was
subjected to the following procedures under the conditions shown
below.
[0068] Anodic Oxidation Coating-Forming Conditions
7 Treatment bath: Oxalic acid 4% by mass Treatment temperature:
28.degree. C. Current density: 2.5 A/dm.sup.2 Treatment time: 80
minutes Thickness of coating: 10 .mu.m
[0069] Lubrication Coating-Forming Conditions
[0070] Composition
8 Polyester resin: 35% by mass Particulate PTFE: 63% by mass
Ceramic particles: 2% by mass (Alumina particles having an average
particle size of 0.05 .mu.m) Baking temperature: 150.degree. C.
Baking time: 15 minutes Thickness of coating: 15 .mu.m
[0071] The test results are shown in Table 1.
Example 5
[0072] The aluminum alloy material for a sliding material was
subjected to the following procedures under the conditions shown
below.
[0073] Anodic Oxidation Coating-Forming Conditions
9 Treatment bath: Sulfuric acid 18% by mass Treatment temperature:
15.degree. C. Current density: 1 A/dm.sup.2 Treatment time: 60
minutes Thickness of coating: 20 .mu.m
[0074] Lubrication Coating-Forming Conditions
[0075] Composition
10 Polyester resin: 40% by mass Particulate PTFE: 59% by mass
Ceramic particles: 1% by mass (Alumina particles having an average
particle size of 0.15 .mu.m) Baking temperature: 200.degree. C.
Baking time: 5 minutes Thickness of coating: 10 .mu.m
[0076] The test results are shown in Table 1.
Comparative Example 1
[0077] The aluminum alloy material for a sliding material 5 was
subjected to only the cleaning procedure. No anodic oxidation
treatment and no lubrication treatment was applied to the cleaned
material.
Comparative Example 2
[0078] The aluminum alloy material for a sliding material was
subjected to an anodic oxidation treatment under the following
conditions, and no lubrication coating-forming treatment was
applied.
[0079] Anodic Oxidation Coating-Forming Conditions
11 Treatment bath: Sulfuric acid 18% by mass Treatment temperature:
15.degree. C. Current density: 1 A/dm.sup.2 Treatment time: 30
minutes Thickness of coating: 20 .mu.m
[0080] Lubrication Coating-Forming Treatment
[0081] This treatment was not applied.
Comparative Example 3
[0082] An aluminum alloy material for a sliding material was
directly subjected to a lubrication treatment under the conditions
shown below. No anode oxidation treatment was applied to the
material.
[0083] Anodic Oxidation Treatment
[0084] This treatment was omitted.
[0085] Lubrication Coating-Forming Conditions
[0086] Composition
12 Polyester resin: 50% by mass Particulate PTFE: 48% by mass
Ceramic particles: 2% by mass (Alumina particles having an average
particle size of 0.05 .mu.m) Baking temperature: 180.degree. C.
Baking time: 5 minutes Thickness of coating: 10 .mu.m
[0087] The test results are shown in Table 1.
Comparative Example 4
[0088] The aluminum alloy material for a sliding material was
subjected to a tin-plating procedure under the following
conditions.
[0089] Tin-Plating Conditions
13 Treatment bath: Alkali-substituted tin-plating bath Treatment
temperature: 60.degree. C. Treatment time: 4 minutes Thickness of
coating: 1 .mu.m
[0090] The test results are shown in Table 1.
14 TABLE 1 Item Seizure test Lubrication Adhesion test Lubrication
oil oil used Not used Used Seizure- Total rubbing Friction Total
rubbing Friction occurring Example No. distance (m) coefficient
distance (m) coefficient load (N) Example 1 50 0.11 >400 0.12
950 2 25 0.11 >400 0.12 950 3 100 0.11 >400 0.12 950 4 75
0.11 >400 0.12 950 5 50 0.11 >400 0.12 950 Com- 1 *.sub.1 --
70 0.15 450 parative 2 *.sub.1 -- >400 0.15 750 Example 3 20
0.11 >400 0.13 500 4 10 0.16 >400 0.14 500 Note: *.sub.1 . .
. Adhesion occurred immediately after the start of rubbing
procedure.
[0091] In view of Table 1, it is clearly confirmed that in Examples
1 to 5, in accordance with the treatment process of the present
invention, the resultant lubrication-treated aluminum alloy
material having excellent resistances to adhesion and seizure was
produced by simple and easy procedures. However, the product of
Comparative Example 1, in which only a cleaning procedure was
applied, exhibited extremely bad properties. The product of
Comparative Example 2 having no lubrication coating exhibited a
very poor resistance to adhesion. The product of Comparative
Example 3 having no anodic oxidation coating also exhibited a poor
resistance to seizure. The tin-plated product of Comparative
Example 4 was unsatisfactory in the adhesion resistance and the
friction coefficient.
[0092] The process of the present invention enables a composite
coating, comprising an anodic oxidation coating and a lubrication
coating and having excellent resistances to adhesion and seizure,
to be formed on an aluminum or aluminium alloy material for sliding
materials by a simple and easy procedures within a short time and
at a low cost. Also, the process of the present invention subjects
the global environment to a very low load.
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