U.S. patent application number 14/372934 was filed with the patent office on 2015-10-15 for sliding member.
This patent application is currently assigned to DAIDO METAL COMPANY LTD.. The applicant listed for this patent is DAIDO METAL COMPANY LTD.. Invention is credited to Hiroyuki ASAKURA, Shigeya HANEDA, Mikihito YASUI.
Application Number | 20150291904 14/372934 |
Document ID | / |
Family ID | 48799166 |
Filed Date | 2015-10-15 |
United States Patent
Application |
20150291904 |
Kind Code |
A1 |
YASUI; Mikihito ; et
al. |
October 15, 2015 |
SLIDING MEMBER
Abstract
Provided is a sliding member which has high seizure resistance
though an overlay layer comprising Ag as the main component is used
therein. The sliding member of an embodiment comprises a base and
an overlay layer which is disposed on the sliding-side surface of
the base and which comprises Ag as the main component and contains
Al. The overlay layer comprising Ag as the main component is
relatively soft. Due to this, the overlay layer comprising Ag as
the main component can ensure high seizure resistance even when the
use of Pb is avoided. Furthermore, the overlay layer comprising Ag
as the main component has excellent thermal conductivity. Due to
this, frictional heat generating at the sliding part rapidly
dissipates to the base side.
Inventors: |
YASUI; Mikihito;
(Inuyama-shi, JP) ; ASAKURA; Hiroyuki;
(Inuyama-shi, JP) ; HANEDA; Shigeya; (Inuyama-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DAIDO METAL COMPANY LTD. |
Nagoya-shi, Aichi |
|
JP |
|
|
Assignee: |
DAIDO METAL COMPANY LTD.
Nagoya-shi, Aichi
JP
|
Family ID: |
48799166 |
Appl. No.: |
14/372934 |
Filed: |
January 15, 2013 |
PCT Filed: |
January 15, 2013 |
PCT NO: |
PCT/JP2013/050538 |
371 Date: |
July 17, 2014 |
Current U.S.
Class: |
508/103 |
Current CPC
Class: |
B32B 15/018 20130101;
C22C 5/06 20130101; F16C 2204/20 20130101; F16C 9/00 20130101; C10M
125/04 20130101; F16C 2204/04 20130101; F16C 33/124 20130101; F16C
17/022 20130101 |
International
Class: |
C10M 125/04 20060101
C10M125/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 18, 2012 |
JP |
2012-007969 |
Claims
1. A sliding member comprising: a base; and an Ag-based overlay
layer disposed on a sliding-side surface of the base and comprising
Al.
2. A sliding member comprising: a base; and an Ag-based overlay
layer disposed on a sliding-side surface of the base and comprising
Al, the overlay layer further comprising at least one of Sn and
Zn.
3. The sliding member according to claim 1, wherein the overlay
layer comprises 0.1% by mass to 15% by mass of Al.
4. The sliding member according to claim 2, wherein the overlay
layer comprises 0.1% by mass to 15% by mass of Al.
Description
TECHNICAL FIELD
[0001] The present invention relates to a sliding member.
BACKGROUND ART
[0002] Conventionally, a sliding member of a slide bearing for an
internal-combustion engine etc. comprises an overlay layer on a
sliding-side surface of a base such as a steel back plate. For such
an overlay layer, there is proposed an overlay layer which
comprises Ag as a main component and to which In, Sn, Bi, or the
like is added, in order to obtain sliding characteristics to the
same degree as those of a sliding member containing Pb, while
avoiding the use of Pb (Patent Literature 1).
[0003] However, although In, Sn, and Bi are softer than Ag, their
thermal conductivities are extremely smaller than that of Ag.
Therefore, an overlay layer which comprises Ag as a main component
and to which In, Sn, or Bi is added cannot easily dissipate the
heat generated in the sliding part with a mating member, to the
base side. As a result, the temperature of an overlay layer of this
type easily rises under severer conditions, causing reduction in
strength and hardness, which causes a problem of easily resulting
in seizure.
CITATION LIST
Patent Literature
[0004] PATENT LITERATURE 1: JP-A-11-257355
SUMMARY OF INVENTION
Technical Problem
[0005] Therefore, an object of the present invention is to provide
a sliding member having high seizure resistance even when an
Ag-based overlay layer is used.
Solution to Problem
[0006] The sliding member according to claim 1 comprises: a base;
and an Ag-based overlay layer disposed on a sliding-side surface of
the base and comprising Al.
[0007] Moreover, the sliding member according to claim 2 comprises:
a base; and an Ag-based overlay layer disposed on a sliding-side
surface of the base and comprising Al, the overlay layer further
comprising at least one of Sn and Zn.
[0008] The Ag-based overlay layer is relatively soft. Therefore,
the Ag-based overlay layer can ensure high seizure resistance even
when the use of Pb is avoided. Moreover, the overlay layer
comprising Ag has excellent thermal conductivity. Therefore, the
frictional heat generated at a sliding part is rapidly dissipated
to the base side. The present inventors have found that the
addition of Al to an Ag-based overlay layer does not cause
significant reduction in the thermal conductivity of the overlay
layer. That is, the addition of In, Sn, Bi, or the like to an
Ag-based overlay layer has been known as a prior art. However, In,
Sn, and Bi as additive elements have small thermal conductivity,
and they have a problem of disturbing rapid dissipation to the base
side of the heat generated in the sliding part with a mating
member. On the other hand, Al in the present invention has a
relatively large thermal conductivity and facilitates the function
of an Ag-based overlay layer, that is, rapid heat dissipation to
the base side by the high thermal conductivity. Therefore, the
sliding member of the present invention can achieve high seizure
resistance even when an Ag-based overlay layer is used, and it can
endure even in the use under severer conditions.
[0009] Moreover, the Ag-based overlay layer of the present
invention may comprise not only Al but also at least one of Sn and
Zn as an additive element. Thus, the essence of the present
invention is in that an Ag-based overlay layer comprising Al is
provided. Therefore, the present invention does not eliminate that
an additive element other than Al and unavoidable impurities are
contained in the overlay layer.
[0010] In the sliding member according to claim 3, the overlay
layer comprises 0.1% by mass to 15% by mass of Al. In the Ag-based
overlay layer, the original thermal conductivity of Ag is exhibited
as the proportion of Ag increases, and the heat dissipation from
the overlay layer to the base side is facilitated. On the other
hand, as the proportion of Al contained in the overlay layer
increases, the thermal conductivity of the overlay layer comes
close to the thermal conductivity of Al from the original thermal
conductivity of Ag. Thus, in the present invention, when adding Al
to an overlay layer, the upper limit of Al is 15% by mass.
BRIEF DESCRIPTION OF DRAWINGS
[0011] FIG. 1 is a schematic sectional view of a sliding member
according to an embodiment.
[0012] FIG. 2 is a schematic view showing the test results of a
sliding member according to an embodiment.
[0013] FIG. 3 is a schematic view showing the conditions of the
seizure resistance test of a sliding member according to an
embodiment.
[0014] FIG. 4 is a schematic view showing a sample used for the
seizure resistance test of a sliding member according to an
embodiment.
DESCRIPTION OF EMBODIMENTS
[0015] Hereinafter, a specific embodiment of a sliding member will
be described.
[0016] First, the procedures for producing a sliding member to be
used as a sample in the present embodiment will be described.
[0017] As shown in FIG. 1, a sliding member 10 comprises a base 11
and an overlay layer 12. The base 11 has a back plate layer 13 and
a Cu-based or Al-based bearing alloy layer 14. The back plate layer
13 is formed from steel. Thus, the base 11 is a so-called bimetal
comprising the steel back plate layer 13 and the Cu-based or
Al-based bearing alloy layer 14. The base 11 formed from the back
plate layer 13 and the bearing alloy layer 14 is shaped into a
semicylindrical or cylindrical shape. The surface of the shaped
base 11 on the side of the bearing alloy layer 14 is subjected to
surface machining such as boring. The surface of the base 11
subjected to surface machining is washed by electrolytic degreasing
and with acid. Thus, after the surface of the base 11 is washed, an
Ag-based overlay layer 12 made of an Ag--Al alloy is formed thereon
by sputtering or the like. Further, instead of sputtering, the
overlay layer 12 can also be formed by plating Ag on a layer made
of Al and by forming an Ag--Al alloy comprising Ag as a main
component utilizing diffusion. In this case, the diffusing capacity
and distribution of Al in the overlay layer 12 can be controlled by
temperature and time. Moreover, one or two or more intermediate
layers (not shown) may be disposed between the base 11 and the
overlay layers 12.
[0018] In the present embodiment, the overlay layer 12 is formed by
sputtering using a magnetron sputtering system (not shown). A
specific example for forming the overlay layer 12 will be described
using the sliding member 10 of sample 1, which is an Example shown
in FIG. 2. In the case of sample 1, a base 11 after washing
consisting of bimetal is mounted on a base mounting part of a
magnetron sputtering system. Moreover, Ag and Al serving as the
materials for the overlay layer 12 are mounted on a target mounting
part of the magnetron sputtering system as targets.
[0019] After the base 11 and Ag and Al which are the targets are
mounted, the chamber of the magnetron sputtering system is
decompressed to 1.0.times.10.sup.-6 Torr and adjusted to
2.0.times.10.sup.-3 Torr by supplying Ar gas. After the pressure of
the chamber is adjusted, the surface of the base 11 is cleaned with
Ar gas. In this case, a bias voltage of 1000 V is applied to the
surface of the base 11. This produces Ar plasma between the base 11
and Ag and Al serving as targets, and reverse sputtering is
performed for 15 minutes. After the cleaning with Ar plasma is
performed, voltage is applied to each target so that a current of 8
A to 14 A may flow into Ag as a target and a current of 0.5 A to 6
A may flow into Al as a target. At this time, the bias voltage
between the base 11 and the targets is set between 100 V and 200 V.
According to these procedures, Ag and Al serving as targets are
sputtered by the collision of Ar ions and form a film on the
surface on the side of the bearing alloy layer 14 of the base
11.
[0020] When a produced sample corresponding to sample 1 was
subjected to EPMA (Electron Probe Micro Analysis), it was verified
that Al was uniformly dispersed in the overlay layer 12 with Ag
being used as a matrix. The amount of Al added to the Ag-based
overlay layer 12 can be controlled by adjusting the mass ratio of
Ag and Al to be mounted on a target mounting part as the targets of
sputtering and the current to be passed through the Ag and Al
serving as targets.
[0021] Sliding members 10 of samples 1 to 16 corresponding to
Examples and sliding members 10 of samples 17 to 20 corresponding
to Comparative Examples as shown in FIG. 2 were formed according to
the above procedures.
(Seizure Resistance Test)
[0022] The resulting sliding members 10 of samples 1 to 16 as
Examples and samples 17 to 20 as Comparative Examples were verified
for seizure resistance by a shim biting test.
[0023] The test conditions of the shim biting test are shown in
FIG. 3. In the shim biting test, a test sample is prepared by
attaching a metal shim 15 having a size of 2 mm.times.2 mm.times.t
to the outer circumferential surface of each of the sliding members
10 of samples 1 to 16 as Examples and samples 17 to 20 as
Comparative Examples, as shown in FIG. 4. In the test, the
thickness t of the shim 15 is set to 10 .mu.m. The thickness t of
the shim 15 can be set from about 10 .mu.m to 30 .mu.m depending on
the conditions of the test. The test sample of the sliding member
10 is installed in a rotational load tester which is a seizure
tester (not shown). The shim 15 is attached to the test sample of
the sliding member 10. Thus, when the test sample of the sliding
member 10 is installed in the seizure tester, a portion
corresponding to the shim 15 on the test sample of the sliding
member 10 projects to the inner circumferential side depending on
the thickness of the shim 15. This projected portion generates heat
by contacting with the test shaft of the seizure tester. Therefore,
the amount of heat generated by the contact of the test sample of
the sliding member 10 with the test shaft is increased by
increasing the load applied to the test sample of the sliding
member 10 in contact with the test shaft. As a result, the lower
the thermal conductivity of the overlay layer 12 in the test sample
of the sliding member 10 is, the more easily seizure will be
occurred on the overlay layer 12 at an early stage. In the test in
the present embodiment, the load applied to the test sample of the
sliding member 10 is increased by 5 MPa every 10 minutes. Then,
when the back temperature of the test sample of the sliding member
10 exceeds 200.degree. C., or when a slide occurs in a shaft drive
belt of the seizure tester by the variation of torque applied to
the seizure tester, it is determined that seizure has been occurred
in the test sample of the sliding member 10.
[0024] Hereinafter, concerning the seizure resistance, verification
results will be examined based on FIG. 2 from the viewpoint of the
maximum specific load without seizure (MPa).
[0025] Samples 1 to 16 are Examples in which Al is added to the
Ag-based overlay layer 12. The seizure resistances of these
Examples have improved as compared with samples 17 to 20 as
Comparative Examples. That is, samples 1 to 16 as Examples have
better seizure resistance by adding Al to the Ag-based overlay
layer 12 than sample 17 in which the overlay layer 12 comprises
only Ag. This is probably because conformability is improved by
adding Al that is softer than Ag, thereby improving seizure
resistance. Similarly, samples 1 to 16 as Examples have better
seizure resistance than sample 18 in which Sn is added to the
Ag-based overlay layer 12 without adding Al, sample 19 in which In
is added similarly, and sample 20 in which Bi is added similarly.
The seizure resistances of samples 1 to 16 have been improved
probably because the thermal conductivity of the overlay layer
thereof is larger than that of samples 18, 19, and 20.
[0026] On the other hand, although the seizure resistances of
samples 15 and 16 as Examples are higher than that of sample 17 as
a Comparative Example, it is lower than that of sample 14 as an
Example. This shows that, in the Ag-based overlay layer 12, an
increase in the amount of Al added tends to reduce the seizure
resistance. That is, when the amount of Al added to the Ag-based
overlay layer 12 becomes excessive, the thermal conductivity of the
overlay layer 12 will be closer to that of Al than Ag. Therefore,
it is considered that samples 15 and 16 in which the amount of Al
added is high have lower seizure resistance than sample 14.
Consequently, it has been found that the addition of Al to the
overlay layer 12 achieves improvement in seizure resistance, and
the addition of a predetermined amount of Al contributes to the
exertion of excellent seizure resistance.
[0027] Moreover, the seizure resistance of sample 5 as an Example
is better than that of sample 4, and the seizure resistance of
sample 8 is better than that of sample 9. Similarly, the seizure
resistance of sample 11 is better than that of samples 12 and 13.
This shows that, in the case of the Ag-based overlay layer 12
comprising Al, when the content of Al is approximately the same,
the seizure resistance can be more improved by not adding Sn, Cu,
Zn, or Bi. That is, when an element having a smaller thermal
conductivity than Al is added to the Ag-based overlay layer 12, the
thermal conductivity of the overlay layer 12 will be smaller than
the case where only Al is added. Therefore, it is considered that
samples 4, 9, 12, and 13 in which an element other than Al is added
to the overlay layer 12 have a lower seizure resistance than a
sample in which substantially only Al is added and the content of
Al in the overlay layer 12 is about the same. Consequently, it has
been found that although seizure resistance can be ensured even if
an element other than Al is added to the overlay layer 12, the
addition of an element other than Al is not advantageous to seizure
resistance.
[0028] Moreover, it has been found that, based on samples 1 to 16
as Examples, the presence or absence of an intermediate layer, the
type of an intermediate layer, and the type of the bearing alloy
layer 14 have only a small influence on seizure resistance.
Furthermore, although not particularly shown, it has been found
that, even if Al is added to the Ag-based overlay layer 12, and, in
addition, hard particles and metal elements other than those shown
in Examples are added thereto, a higher seizure resistance than
that of the overlay layer 12 comprising only Ag can be achieved.
Consequently, if Al is added to the Ag-based overlay layer 12, an
improvement in seizure resistance can be achieved regardless of the
presence or absence of other additive components or the type of
additive components, as long as the amount of Al added is not
excessive.
[0029] Moreover, in the sliding member 10, other layers such as a
conformable layer may further be disposed on the sliding-side
surface of the Ag-based overlay layer 12. A further layer such as a
conformable layer is preferably a layer comprising, for example, Bi
or a Bi alloy. Although not particularly shown, a sliding member of
an embodiment in which a conformable layer is disposed also has
excellent seizure resistance and, in particular, had excellent
initial conformability. Thus, the sliding member 10 of an
embodiment in which a conformable layer is disposed was naturally
able to exhibit high seizure resistance even if the conformable
layer was worn out to expose the Ag-based overlay layer 12.
[0030] The present invention as described above is not limited to
the above embodiments and can be applied to various embodiments
without departing from the scope of the present invention.
REFERENCE SIGNS LIST
[0031] 10 Sliding member [0032] 11 Base [0033] 12 Overlay layer
[0034] 13 Back plate layer [0035] 14 Bearing alloy layer
* * * * *