U.S. patent application number 15/296302 was filed with the patent office on 2017-02-09 for sliding member and sliding bearing.
This patent application is currently assigned to Taiho Kogyo Co., Ltd.. The applicant listed for this patent is Taiho Kogyo Co., Ltd.. Invention is credited to Hitoshi Wada.
Application Number | 20170037899 15/296302 |
Document ID | / |
Family ID | 51624161 |
Filed Date | 2017-02-09 |
United States Patent
Application |
20170037899 |
Kind Code |
A1 |
Wada; Hitoshi |
February 9, 2017 |
SLIDING MEMBER AND SLIDING BEARING
Abstract
A sliding member includes a base layer that includes soft
particles made of a soft material deposited in a matrix and a soft
layer made of a soft material. The soft material is softer than the
matrix, the soft layer is formed on a surface of the base layer,
and an average epitaxial index of the soft particles at the
boundary portion of the sliding member is equal to or greater than
70% and less than or equal to 100%. The epitaxial index of a soft
particle at the boundary portion is a ratio of: a portion of a
length between a first endpoint and a second endpoint of a soft
particle where an edge of the boundary portion is not visible
within an area less than 1 .mu.m from the length between the first
endpoint and the second endpoint, to the length between the first
endpoint and the second endpoint.
Inventors: |
Wada; Hitoshi; (Aichi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Taiho Kogyo Co., Ltd. |
Aichi |
|
JP |
|
|
Assignee: |
Taiho Kogyo Co., Ltd.
Aichi
JP
|
Family ID: |
51624161 |
Appl. No.: |
15/296302 |
Filed: |
October 18, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14773415 |
Sep 8, 2015 |
9500228 |
|
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PCT/JP2014/058265 |
Mar 25, 2014 |
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15296302 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16C 17/02 20130101;
F16C 2204/36 20130101; C30B 29/02 20130101; B32B 15/01 20130101;
C30B 30/02 20130101; C30B 7/12 20130101; F16C 2204/10 20130101;
C22C 9/02 20130101; F16C 33/12 20130101; C22C 12/00 20130101; F16C
33/14 20130101; C30B 19/103 20130101; F16C 2202/04 20130101; F16C
2223/30 20130101; F16C 33/122 20130101 |
International
Class: |
F16C 33/12 20060101
F16C033/12; C30B 29/02 20060101 C30B029/02; C30B 7/12 20060101
C30B007/12; F16C 17/02 20060101 F16C017/02; F16C 33/14 20060101
F16C033/14 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 29, 2013 |
JP |
2013-072010 |
Claims
1. A sliding member, comprising: a base layer comprising soft
particles made of a soft material deposited in a matrix; and a soft
layer made of a soft material, wherein the soft material is softer
than the matrix, wherein the soft layer is formed on a surface of
the base layer, wherein an average epitaxial index of the sliding
member is equal to or greater than 70% and less than or equal to
100%, wherein the average epitaxial index of the sliding member is
an average of all of an epitaxial index of the soft particles at
the boundary portion, and wherein the epitaxial index of the soft
particles at the boundary portion is a ratio of: a portion of a
length between a first endpoint of a soft particle and a second
endpoint of the soft particle where an edge of the boundary portion
is not visible within an area not farther than 1 .mu.m from the
length between the first endpoint and the second endpoint, to the
length between the first endpoint and the second endpoint.
2. The sliding member according to claim 1, wherein the soft layer
comprise an epitaxial growth portion that comprises epitaxially
grown soft particles.
3. The sliding member according to claim 2, wherein the matrix is
made of Cu alloy, and the soft material is Bi.
4. A sliding bearing, comprising: a base layer comprising soft
particles made of a soft material deposited in a matrix; and a soft
layer made of a soft material, wherein the soft material is softer
than the matrix, wherein the soft layer is formed on a surface of
the base layer, wherein an average epitaxial index of the sliding
member is equal to or greater than 70% and less than or equal to
100%, wherein the average epitaxial index of the sliding member is
an average of all of an epitaxial index of the soft particles at
the boundary portion, and wherein the epitaxial index of the soft
particles at the boundary portion is a ratio of: a portion of a
length between a first endpoint of a soft particle and a second
endpoint of the soft particle where an edge of the boundary portion
is not visible within an area not farther than 1 .mu.m from the
length between the first endpoint and the second endpoint, to the
length between the first endpoint and the second endpoint.
5. The sliding bearing according to claim 4, wherein the soft layer
comprise an epitaxial growth portion that comprises epitaxially
grown soft particles.
6. The sliding bearing according to claim 5, wherein the matrix is
made of Cu alloy, and the soft material is Bi.
7. The sliding member according to claim 1, wherein the average
epitaxial index is 70%.
8. The sliding bearing according to claim 4, wherein the average
epitaxial index is 70%.
Description
TECHNICAL FIELD
[0001] The present invention relates to a sliding member and a
sliding bearing whereon a mating member is sliding.
BACKGROUND ART
[0002] A technology that an intermediate layer made of a material,
e.g. Ni on Cu alloy is formed and an overlay made of Bi is formed
on the intermediate layer, is known (Patent documents
JP2011-163382A). Accordingly, the overlay made of soft Bi can
improve conformability.
CITATION LIST
Patent Literature
[0003] [PTL1]
JP2011-163382A
SUMMARY OF THE INVENTION
Technical Problem
[0004] However, there is a problem that adhesiveness between the
intermediate layer and the overlay is poor. That is, there is a
problem that the overlay is peeled from the intermediate layer
because, cleavage fractures progress between the intermediate layer
and the overlay.
[0005] The present invention is made in consideration of such a
problem, and provides a technology to improve adhesiveness of a
soft layer.
Solution to Problem
[0006] The present invention discloses a sliding member that
includes a base layer that includes soft particles made of a soft
material deposited in a matrix and a soft layer made of a soft
material. The soft material is softer than the matrix, the soft
layer is formed on a surface of the base layer, and an average
epitaxial index of the sliding member is equal to or greater than
70% and less or equal to 95%. The average epitaxial index of the
sliding member is an average of all of an epitaxial index of the
soft particles at the boundary portion. The epitaxial index of the
soft particles at the boundary portion is a ratio of a portion of a
length between a first endpoint of a soft particle and a second
endpoint of the soft particle where an edge of the boundary portion
is not visible within an area not farther than 1 .mu.m from the
length between the first endpoint and the second endpoint, to the
length between the first endpoint and the second endpoint
[0007] The adhesiveness between the intermediate layer and the
overlay can be improved, because the soft layer made of the soft
material, same to the material of the soft particles deposited in
the matrix, adhere to the soft particles. The soft particles
adhered to the soft layer can be anchors to improve the
adhesiveness of the soft layer with the base layer, because the
soft particles are originally deposited in the base layer.
Especially, the epitaxial growth portion of the soft layer can
strongly adhere to the soft particles of the base layer, because
the epitaxial growth portion is formed of the soft material
epitaxially grown from the soft particles. The strongly adhered
portion comprised of the epitaxial growth portion and the soft
particles of the base layer, is formed penetrating an interface
between the base layer and the soft layer. Therefore, the strongly
adhered portion can refrain progress of the cleavage fractures at
the interface between the base layer and the soft layer and can
improve the adhesiveness between the base layer and the soft
layer.
[0008] The base layer can be any layers as long as including the
matrix and the soft particles, and the base layer can be supported
by the back metal. The soft material can be any materials that are
softer than the matrix and are able to deposit in the matrix when
the base layer is formed. For example, the soft material can be
included in the lining in an amount which is more than solid
solubility limit for the matrix. The soft layer includes a portion
adhering to the matrix of the base layer and a portion adhering to
the soft particles exposed on the surface of the base layer. In the
portion adhering to the soft particles exposed on the surface of
the base layer, the epitaxial portion epitaxially grown from the
soft particles is formed.
[0009] The matrix of the base layer can be Cu alloy and the soft
material can be Bi. The conformability can be realized by forming
the soft layer made of Bi, because Bi is softer than Cu alloy. In
addition, Cu alloy means the alloy including Cu as a main
component. The soft particles of Bi can deposit in Cu alloy because
Bi does almost not have solid solubility for Cu. However, the
matrix of the base layer does not limit to Cu alloy and the
material of the matrix can be selected according to circumstances
e.g. the hardness of the mating member or the load affecting to the
mating member. Further, materials e.g. Pb, Sn, In as long as softer
than the matrix and are able to deposit in the matrix, can be the
soft material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a perspective view of a sliding member.
[0011] FIGS. 2A and 2B are cross sectional views of sliding
member.
[0012] FIGS. 3A and 3B are graphs of acoustic emission.
[0013] FIGS. 4A and 4B are photographs showing cross sectional view
of sliding member.
DESCRIPTION OF EMBODIMENT
[0014] Preferred embodiments of the present invention will be
described in the following order.
(1) First Embodiment (1-1) Configuration of a sliding member:
[0015] (1-2) Measuring method:
[0016] (1-3) Manufacturing method of a sliding member:
(2) Other Embodiment
(1) First Embodiment
(1-1) Configuration of a Sliding Member
[0017] FIG. 1 is a perspective view of a sliding member 1 as an
embodiment of the present invention. The sliding member 1 is
comprised of a back metal 10, a lining 11 and an overlay 12. The
sliding member 1 is a metal member in a half pipe shape that is a
bisection shape of a hollow cylinder sectioned at a diametral
plane. A cross-sectional shape of the sliding member 1 is a half
circular arc. A sliding bearing A can be manufactured by combining
two sliding members 1 to be in a cylindrical shape. A mating shaft
2 (e.g. a crankshaft of an engine) is inserted in an inner hollow
space of the sliding bearing A. An outer diameter of the mating
shaft 2 is a little smaller than an inner diameter of the sliding
bearing A. A lubricating oil (e.g. engine oil) is provided to a
clearance formed between an outer surface of the mating shaft 2 and
an inner surface of the sliding bearing A. Then the outer surface
of the mating shaft 2 can slide on the inner surface of the sliding
bearing A.
[0018] The sliding member 1 has a layered structure that the back
metal 10, the lining 11 and the overlay 12 are laminated in order
from a far side of the center of curvature. Therefore, the back
metal 10 is an outermost layer of the sliding member 1 and the
overlay 12 is an innermost layer of the sliding member 1. Each of
the back metal 10, the lining 11 and the overlay 12 has a constant
thickness in a circumferential direction. The thickness of the back
metal 10 is 1.3 mm. The thickness of the lining 11 is 0.2 mm. And
the thickness of the overlay 12 is 10 .mu.m. A radius of a surface
of the overlay 12 facing the center of curvature (an inner radius
of the sliding member 1) is 40 mm. In this specification, "the
inner side" means a side nearby the center of curvature of the
sliding member 1 and "the outer side" means an opposite side to the
center of curvature of the sliding member 1. The inner surface of
the overlay 12 corresponds to a sliding surface between the sliding
member 1 and the mating shaft 2.
[0019] The back metal 10 is made of steel consisted of 0.15 wt %
(weight percentage for the back metal 10) of C (copper), 0.06 wt %
of Mn (manganese) and the balance Fe (ferrum). In addition, the
back metal 10 can be made of a material that can support a load
transmitted from the mating shaft 2 through the lining 11 and the
overlay 12. Therefore the back metal 10 can be made of a material
other than the steel. The lining 11 is a layer laminated on an
inner surface of the back metal 10. The lining 11 corresponds to a
base layer of the present invention. The lining 11 is consisted of
10 wt % (weight percentage for the lining 11) of Sn (tin), 8 wt %
of Bi (bismuth) and the balance. The balance is consisted of Cu and
unavoidable impurities. The unavoidable impurities included in the
lining 11 are elements e.g. Mg (magnesium), Ti (titanium), B
(boron), Pb (lead) and Cr (chromium). The unavoidable impurities
are contaminated when the materials of the lining 11 are refined
and/or scraped. Total weight percentage of the unavoidable
impurities is less than 1.0 wt %.
[0020] FIG. 2A is a schematic cross sectional views of the sliding
member 1. In FIG. 2A, the curve of the sliding member 1 is ignored.
In the lining 11, Bi particles 11b are deposited in a matrix 11a
made of Cu--Sn alloy. Bi particles 11b are softer than the matrix
11a and correspond to the soft particles of the present invention.
Strength and wear resistance can be improved by adopting hard
Cu--Sn alloy as the matrix 11a of the lining 11.
[0021] The average equivalent circle diameter of Bi particles 11b
on the cross sectional plane of the lining 11 was 100 .mu.m. That
is, the average area of Bi particles 11b on the cross sectional
plane of the lining 11 was 2500.PI. .mu.m.sup.2. The area ratio of
Bi particles 11b on the cross sectional plane of the lining 11 was
10%. The average equivalent circle diameter, the average area and
the area ratio of Bi particles 11b on a boundary surface X between
the lining 11 and the overlay 12 can be considered as same as the
average equivalent circle diameter, the average area and the area
ratio of Bi particles 11b on arbitrary cross sectional planes,
because the distribution of Bi particles 11b in the lining 11 has
uniformity and no directional dependency.
[0022] The overlay 12 is a layer laminated on an inner surface of
the lining 11. The overlay 12 corresponds to the soft layer of the
present invention. The inner surface of the lining 11 corresponds
to the boundary surface X between the lining 11 and the overlay 12.
The overlay is consisted of Bi and unavoidable impurities. The
unavoidable impurities included in the overlay 12 are elements e.g.
Sn, Fe and Pb. The unavoidable impurities are impurities
contaminated from plating liquid for the overlay 12. In the lining
11, total weight percentage of the unavoidable impurities is not
more than 1.0 wt % and the weight percentage of Bi is not less than
99%.
[0023] The overlay 12 includes epitaxial growth portions 12b and
original growth portions 12a. The epitaxial growth portions 12b are
portions made of Bi crystal epitaxially grown from Bi particles 11b
exposed on the inner surface of the lining 11, as growth starting
points. Therefore, the crystal grain structure of the epitaxial
growth portions 12b is identical to the crystal grain structure of
Bi particles 11b included in the lining 11. The crystal grain
structure of Bi particles 11b included in the lining 11 is
determined according to the crystal growth condition of Bi
particles 11b in the lining 11.
[0024] The epitaxial growth portions 12b strongly adhere to Bi
particles 11b included in the lining 11, because the epitaxial
growth portions 12b are portions made of Bi crystal epitaxially
grown from Bi particles 11b exposed on the inner surface of the
lining 11. The united portions formed by strong adhesion between
the epitaxial growth portions 12b and Bi particles 11b included in
the lining 11, is shaped to penetrate the boundary surface X
between the lining 11 and the overlay 12.
[0025] FIG. 2B is a schematic diagram showing a state wherein the
overlay 12 is peeled from the lining 11. As shown in the FIG. 2B,
even if a cleavage fracture E peeling the overlay 12 from the
lining 11 is arisen, the united portions formed by adhesion between
the epitaxial growth portions 12b and Bi particles 11b included in
the lining 11 can refrain the cleavage fracture E from progressing.
Therefore, adhesiveness between the lining 11 and the overlay 12
can be improved.
[0026] FIG. 3A and FIG. 3B are graphs showing magnitude of acoustic
emission in case a friction force is worked on the sliding surface
of the sliding member 1. In the FIG. 3A and FIG. 3B, a horizontal
axis shows a vertical load worked on the overlay 12, and a first
vertical axis (right side axis) shows the friction force. As shown
in the FIG. 3A and FIG. 3B, the friction force (broken line) is
mostly proportional to the vertical load. A second vertical axis
(left side axis) in the FIG. 3A and FIG. 3B shows the magnitude of
the acoustic emission. The larger value of the second vertical axis
is, the larger the magnitude of the acoustic emission is. The
magnitude of the acoustic emission corresponds to a sound pressure
of a sound generated when the friction force was worked on the
overlay 12.
[0027] FIG. 3A shows the acoustic emission in case the friction
force was worked on the sliding surface of the sliding member 1
(embodiment of the present invention) whose average epitaxial index
was 70%. FIG. 3B shows the acoustic emission in case the friction
force was worked on the sliding surface of the sliding member 1
(comparison example) whose maximum epitaxial index was 10%. The
acoustic emission is a sound wave generated by inner fracture of
the sliding member 1 caused by the friction force worked on the
sliding surface. The inner fracture of the sliding member 1 that is
main cause of the acoustic emission, is generally considered to the
cleavage fracture at the boundary surface X between the lining 11
and the overlay 12. The reason is that the lining 11 and the
overlay 12 are easy to peel because Bi composing the overlay 12 is
not solid-solved in Cu and does not form a compound with Cu. The
epitaxial index is an index that becomes larger if area occupying
ratio of the epitaxial growth portions 12b on the boundary surface
X between the lining 11 and the overlay 12. Details of the
epitaxial index will be explained hereinafter.
[0028] Comparing FIG. 3A and FIG. 3B, the acoustic emission almost
did not occur in the sliding member 1 whose average epitaxial index
was 70% shown in the FIG. 3A, meanwhile the acoustic emission
occurred in the sliding member 1 whose average epitaxial index is
less than 50% shown in the FIG. 3B. Therefore, in case the
epitaxial index becomes large, the cleavage fracture at the
boundary surface X between the lining 11 and the overlay 12 can be
refrained, and adhesiveness between the lining 11 and the overlay
12 can be improved.
[0029] The original growth portions 12a are the portions made of Bi
crystal epitaxially grown from crystal nucleus formed on the
surface of the matrix 11a. Therefore, Bi crystal grain structure in
the original growth portions 12a is determined according to the
crystal growth condition of forming the overlay 12 on the surface
of the lining 11. Consequently, Bi crystal grain structure of the
original growth portions 12a and the crystal grain structure of the
epitaxial growth portions 12b are determined according to different
crystal growth conditions each other. Therefore it can be said that
the overlay is composed of the original growth portions 12a and the
epitaxial growth portions 12b whose Bi crystal grain structure are
different each other.
[0030] A boundary portion Y (shown by a bold line in the FIG. 2A)
whose Bi crystal grain structures is discontinuous, is formed
between the original growth portions 12a and the epitaxial growth
portions 12b, because the original growth portions 12a and the
epitaxial growth portions 12b have different Bi crystal grain
structures each other. In the present embodiment, the boundary
portion Y between the original growth portions 12a and the
epitaxial growth portions 12b has a convex shape protruding to the
inner side of the sliding member 1
[0031] In the boundary portion Y between the original growth
portions 12a and the epitaxial growth portions 12b, Bi crystal
grain boundary is also discontinuous. Therefore, as shown in the
FIG. 2B, even if a fatigue fracture D cleaving the crystal grain
boundary in the original growth portions 12a occurs, it can be
refrained the fatigue fracture D from penetrating the boundary
portion Y between the original growth portions 12a and the
epitaxial growth portions 12b. In the present embodiment, it can be
refrained transmission of the fatigue fracture D from advancing
into Bi particles 11b included in the lining 11, because the
boundary portion Y between the original growth portions 12a and the
epitaxial growth portions 12b exists in the overlay (closer to the
overlay 12 than the boundary surface X between the lining 11 and
the overlay 12). Consequently, deterioration of mechanical
characteristics of the lining 11 can be refrained.
(1-2) Measuring Method
[0032] The measurement values mentioned in the embodiment were
measured by methods explained hereinafter.
[0033] The masses of atoms included in the layers of the sliding
member 1 were measured by an ICP (Inductively Coupled Plasma)
atomic emission spectrometry analyzer (ICPS-8100 made by SHIMADZU
CORPORATION).
[0034] The average equivalent circle diameter of Bi particles 11b
included in the lining 11 was measured by the methods as follows.
First, the arbitrary cross sectional planes of the lining 11 (not
limited in directions vertical to the rotation axis of the mating
shaft 2) were polished by alumina abrasive grains whose diameter
were 2 .mu.m. Observation image (backscattered electron images) was
prepared by imaging an observation view field covering an area of
0.02 mm.sup.2 on the arbitrary cross sectional plane of the lining
11 by an electron microscope (JSM-6010A made by JEOL Ltd.) with 500
times of the optical magnification. Next, the observation image was
input to an image analyzing system (LUZEX II made by NIRECO
CORPORATION) and images of Bi particles 11b were detected from the
observation image. There were edges (boundary where brightness,
chroma or hue was changed more than a predetermined threshold)
along outlines of the images of Bi particles 11b. So, areas closed
by the edges are detected from the observation image, as the images
of Bi particles 11b, by the image analyzing system.
[0035] Next, the images of Bi particles 11b were extracted from the
observation image and the projected area-equivalent diameters
(measurement parameter: HEYWOOD) of the images of all Bi particles
11b was measured by the image analyzing system. The projected
area-equivalent diameter was a diameter of a circle having an area
identical to the area of the image of Bi particles 11b and a
real-space length converted from the diameter of image of Bi
particles 11b based on the optical magnification. Further, an
arithmetic mean (sum total/number of Bi particles 11b) of projected
area-equivalent diameters of all Bi particles 11b was measured as
the average equivalent circle diameter of Bi particles 11b.
Further, the total area of Bi particles 11b was measured by
multiplying the area of a circle with a diameter identical to the
average equivalent circle diameter of Bi particles 11b and the
number of Bi particles 11b existing in the observation view field.
Finally, the area ratio of Bi particles 11b was measured by
dividing the total area of Bi particles 11b by an area of the
observation view field. In addition, the projected area-equivalent
diameters less than 1.0 .mu.m were ignored for calculation of the
average equivalent circle diameter of Bi particles 11b. e.g.,
because the projected area-equivalent diameters less than 1.0 .mu.m
might decrease a reliability of the projected area-equivalent
diameter and a reliability of detection of the components.
[0036] The epitaxial index was measured by the methods as follows.
First, a diametral cross sectional plan of the sliding member 1 was
polished by a cross section polisher. Observation image was
prepared by imaging an arbitrary observation view field covering an
area of 0.02 mm.sup.2 (rectangular area with 0.1 mm vertical length
and 0.2 mm horizontal width) on the cross sectional plane of the
lining 11 by an electron microscope with 7000 times of the optical
magnification. FIG. 4A and FIG. 4B are photographs of the
observation images. As shown in the FIG. 4A, a portion of the
observation image where Bi particles 11b existed at the boundary
surface X between the lining 11 and the overlay 12 is visually
observed. Further, as shown in the FIG. 4B, a line segment L
(broken line) connecting both endpoints of the Bi particle 11b at
the boundary surface X was detected and a length of the line
segment L was measured.
[0037] Next, portions of the line segment L that edges existed in
an area not farther than 1 .mu.m and portions B (arrow) of the line
segment L that edge did not exist in the area not farther than 1
.mu.m were detected. The epitaxial index was measured by dividing
the length of the portions B by the length of the line segment L.
The epitaxial index of each of Bi particles 11b existing at the
boundary surface X was measured.
[0038] In addition, the minimum epitaxial index of the sliding
member 1 (embodiment of the present invention) shown in FIG. 3A was
50%, the average epitaxial index of the same was 70% and the
maximum epitaxial index of the same was 95%. On the other hand, the
maximum epitaxial index of the sliding member 1 (comparison
example) shown in the FIG. 3B was 10%. In addition, the continuous
edge connecting both endpoints of the line segment L corresponds
the boundary portion Y (one dot chain line) between the original
growth portions 12a and the epitaxial growth portions 12h. The edge
can be found between the original growth portions 12a and the
epitaxial growth portions 12b because the size and the array
direction of the Bi crystal grains are different between the
original growth portions 12a and the epitaxial growth portions 12b.
In addition, the edge can be detected by the image analyzing system
input the observation image.
(1-3) Manufacturing Method of a Sliding Member
[0039] In the beginning, a low carbon steel flat plate whose
thickness was same as the thickness of the back metal 10 was
prepared.
[0040] Next, the powder of the materials for the lining 11 was
scattered on the flat plate made of the low carbon steel.
Concretely, Cu powder, Bi powder and Sn powder were scattered on
the low carbon steel flat plate to be same weight ratio as the
weight ratio of the components of abovementioned lining 11. As long
as the weight ratio of the components of the lining 11 can be
satisfied, powder of alloy e.g. Cu--Bi and Cu--Sn can be scattered
on the low carbon steel flat plate. The particle diameter of the
powder was regulated to be not larger than 150 .mu.m by a test
sieve (JIS Z8801).
[0041] Next, the low carbon steel flat plate and the powder
scattered on the low carbon steel flat plate were sintered. The
sinter was performed in inert atmosphere and the sintering
temperature was set to the range of 700 to 1000.degree. C. Cooling
was performed after sinter.
[0042] The Cu alloy layer was formed on the low carbon steel flat
plate after completion of the cooling. The soft Bi particles 11b
deposited were included in this Cu alloy layer.
[0043] Next, the low carbon steel flat plate whereon the Cu alloy
layer was formed, was processed by the press working to be in the
bisection shape of the hollow cylinder sectioned at a diametral
plane. Then, the press working was performed to make the outer
diameter of the low carbon steel flat plate same as the outer
diameter of the sliding member 1.
[0044] Next, the Cu alloy layer formed on the low carbon steel flat
plate was processed by grinding. Then, the grinding depth was
controlled to make the thickness of the Cu alloy layer formed on
the low carbon steel flat plate same as the thickness of the lining
11. The grinding was performed by the lathe on which it set the
cutting tool made of the abrasive e.g. sintered diamonds. The
surface of the lining 11 after grinding was the boundary surface X
between the lining 11 and the overlay 12.
[0045] Next, the overlay 12 was formed by laminating Bi as the soft
material with thickness of 10 .mu.m on the surface of the lining
11, by the electroplating. The procedure of the electroplating was
as follows. First, the degreasing of the surface of the lining 11
was performed by flowing direct current to the surface of the
lining 11 in an electrolyte. Next, the surface of the lining 11 was
rinsed with water. Further, unnecessary oxides on the surface of
the lining 11 except for oxide films formed by an anodic oxidation
were removed by pickling. After that, the surface of the lining 11
was rinsed with water again. After completion of abovementioned
pretreatments, the electroplating was performed by supplying
current to the surface of the lining 11 immersed in the plating
liquid. The composition of the plating liquid included Bi with
density range of 10 to 50 g/L, the organic sulfonic acid with
density range of 25 to 100 g/L and additive agents with density
range of 0.5 to 50 g/L. The temperature of the plating liquid was
25.degree. C. Further, the current supplied to the surface of the
lining 11 was direct current and the current density of the direct
current was in the range of 0.5 to 5.0 A/dm.sup.2.
[0046] By performing the electroplating as remarked above, Bi
crystal was epitaxially grown from Bi particles 11b existing on the
boundary surface X between the lining 11 and the overlay 12 and the
epitaxial growth portions 12b were formed in the overlay 12. After
completion of lamination of the overlay 12, the manufacturing of
the sliding member 1 was completed by rinsing with water and
drying. Further the sliding bearing A was manufactured by combining
two sliding members 1 to be in the cylindrical shape.
(2) Other Embodiment
[0047] The sliding member 1 composing the sliding bearing A that
supports the crankshaft for the engine was exemplary shown in the
above embodiment, the sliding bearing A for other use can be made
of the sliding member 1 of the present invention. For example, gear
bushes for transmission, piston bushes and boss bushes can be made
of the sliding member 1. Needless to say, the sliding member 1 can
be parts whereon any mating members other than shafts are sliding.
The matrix of the lining 11 does not limit to Cu alloy, the
material of the matrix can be selected according to the hardness of
the mating shaft 2. Further, materials e.g. Pb, Sn, In (indium)
that are softer than the matrix and are able to deposit in the
matrix, can be the soft material.
DESCRIPTION OF THE REFERENCE NUMERALS
[0048] 1:sliding member, 2:mating shaft, 10:back metal, 11:lining,
11a:matrix, 11b:Bi particles, 12:overlay, 12a:original growth
portion, 12b:epitaxial growth portion, X:boundary surface,
Y:boundary portion
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