JPH04210165A - Sliding member - Google Patents

Abstract

PURPOSE:To obtain a piston ring excellent in abrasion resistance and initial conformability by setting the average particle size of silicon carbide in an upper composite plating layer to within the range of 0.2 to 3mum, and using a layer in which particles of average size 0.2 to 3mum are mixed with those of average size 5 to 15mum as a lower composite plating layer located beneath the upper layer. CONSTITUTION:A composite plating film 5 having silicon carbide 3 of average particle size 1mum and silicon carbide 2 of average particle size 10mum dispersed in a matrix of a nickel-phosphorous alloy 4 and deposited as eutectoid materials is formed by electrodeless plating into a thickness of 30mum on the surface of a base member 1 and the base member 1 is then filtrated through plating bath to form a composite plating layer 6 of thickness 5mum including only the silicon carbide 3 of average particle size 1mum. The base member 1 is then heated at 400 deg.C in a heat treatment furnace so that the adhesion property of the silicon carbide to the matrix on the surface of the base is strengthened, the silicon carbide having hardness as high as Hv 1000 and serving as an eutectoid material. The base member is then surface finished by wrapping to provide a smooth surface having a center-line average roughness Ra of 0.06mum or less.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a sliding member having excellent initial conformability and wear resistance.

(Prior Art and Problems to be Solved by the Invention) Conventionally, piston rings used in internal combustion engines such as automobiles and motorcycles, which slide at high speed on cylinder liners, are required to have wear resistance. For this reason, piston rings whose outer peripheral sliding surfaces are plated with hard chrome have been widely used. However, the plating process takes a long time and
There is a problem in that it is expensive to take measures to prevent pollution caused by plating waste liquid, which increases plating costs. In addition, as a method other than this, dispersion plating using hard fine particles such as silicon carbide as a dispersion has been adopted.

All of these conventional surface-treated piston rings have excellent wear resistance, but piston rings with even better wear resistance and initial conformability are required as speeds increase.

(Means for Solving the Problems) The present invention provides a sliding member for use in power machinery and textile equipment that has better wear resistance and initial conformability than the conventional surface-treated sliding members. The purpose is to

In order to achieve the above object, the present invention provides a sliding member in which a composite plating layer having silicon carbide as a eutectoid and a nickel alloy as a matrix is provided on at least the sliding surface of a metal base material. The average particle size of hard fine particles in the upper layer within 1 μm to 5 μm from the surface is 0.2 μm to 3 μm.
m, and the particle size of the hard fine particles of the subsequent lower composite plating layer is a mixed layer in which particles with an average particle size of 0.2 μm to 3 μm and particles with an average particle size of 5 μm to 15 μm are uniformly mixed, Moreover, the surface roughness of the composite plating layer is set to a center line average roughness RaO of 2 μm or less, and the composite plating layer is formed with a thickness of 8 μm to 35 μm.

The average particle size of silicon carbide in the layer within 5 μm from the surface layer of the composite plating layer is preferably 0.2 μm to 3 μm, and 0.2 μm.
If it is less than 3 μm, the wear resistance will be poor, and if it exceeds 3 μm, the surface roughness of the sliding member will become rough after plating, making it difficult to perform surface lapping and polishing after plating. In addition, the layer with an average particle size of silicon carbide of 0.2 μm to 3 μm is 1 μm thicker than the surface layer.
It is preferable that it is between 1 μm and 5 μm. If it is less than 1 μm, the surface roughness of the sliding member after plating will become rough due to the influence of the large silicon carbide in the lower layer, making it difficult to perform surface burping and polishing after plating, or causing large carbonization. Silicon particles appear on the surface before the operation is completed and wear out the mating material. 5
If it is more than μm, the initial period of high wear will be long and the life of the sliding member will be shortened.

The silicon carbide fine particles in the lower layer of composite plating have an average particle size of 0.2
A mixed layer in which particles with a diameter of 5 μm to 3 μm and particles with an average particle size of 5 μm to 15 μm were uniformly mixed was formed when the 5 μm layer was formed.
Particles of ~15 μm have higher wear resistance than particles of 0.2 μm to 3 μm, and play the main role of supporting friction in the steady state after initial wear and reducing wear of sliding members.
The m particles have the function of suppressing rapid wear of the N1-P plating layer of the matrix and gradually exposing particles of 5 μm to 15 μm on the ring surface. The ratio by weight is preferably 1 = 1 to 1:5, and if the ratio of particles of 5 μm to 15 μm is less than 1 = 1, there is no effect of improving wear resistance;
: If it is 5 or more, after the initial wear of the surface layer containing only particles of 0.2 μm to 3 μm, particles of 5 μm to 15 μm will rapidly appear on the surface, resulting in roughness of the surface and increased wear of the mating material. .

In addition, the amount of eutectoid silicon carbide fine particles in the composite plating layer is 2 to 2.
20 wt% is good; if it is less than 2 wt%, the wear resistance of the composite plating layer is poor, and if it is more than 20-t%, the proportion of silicon carbide on the surface of the dispersion plating becomes large, resulting in poor sliding properties.

Furthermore, if the thickness of the composite plating layer is less than 8 μm, the life of the sliding member will be short, and if it exceeds 35 μm, the plating process cost will increase or pits will easily form in the plating.

(Example) Hereinafter, one example of the present invention will be described based on the drawings.
- As shown in Figure 1, a cylindrical steel material (315CK) is cut to form a base material (1), and then carburized and quenched.

After the base material (1) is subjected to plating pretreatment such as degreasing and pickling, at least the surface of the sliding surface is electroless plated.
After forming a composite plating film of 30 μm in which silicon carbide (3) with an average grain size of 1 μm and silicon carbide (2) with an average grain size of 10 μm are dispersed and precipitated as eutectoid substances in a matrix of nickel-phosphorus alloy (4), plating is performed. The bath is filtered through a 3 μm filter to form a 5 μm composite plating film containing only silicon carbide (3) with an average particle size of 1 μm in the matrix.

The base material (1) coated with the SiC composite N1-P amorphous alloy is heat treated in a heat treatment furnace at a heat treatment temperature of 400° C. for about 1 hour.

In this way, in the SiC composite N1-P amorphous alloy plating, the nickel-phosphorous matrix is crystallized,
Changes to a mixed structure of Ni, -P and Ni crystals, forming the base material (1)
The surface has a high hardness of Hv 1000, and the adhesion between silicon carbide, which is a eutectoid substance, and the matrix is strengthened, and silicon carbide (3) with an average particle size of 1 μm and silicon carbide (2) with an average particle size of 10 μm are eutectoid. A composite plating layer (5) in which silicon carbide (3) with an average particle size of 1 μm was dispersed and precipitated as a eutectoid material was formed.

Next, the sliding surface is polished by lapping,
A desired sliding member having a smooth surface with a center line average roughness RaO of 06 μm or less was constructed.

Next, the sliding properties of the sliding member having the film obtained in the above example were investigated using a bottle-on-disk type abrasion tester.

The test pieces used were a pin-shaped test piece and a disc-shaped test piece, on which the film obtained by the present invention (A) and the conventional dispersion plating film (B) were formed.

Using each of the above test pieces, the same coatings were slid against each other to examine changes in the coefficient of friction and changes in the amount of wear.

Test conditions are test temperature 180°C2 sliding speed 3.0m
/sec, and a 100-hour wear test was conducted using engine oil (SAE #20) as the lubricant. As shown in Figures 2 and 3, the test results show that the coating formed by the present invention (A) has a friction coefficient at the initial stage that is about the same as that of the conventional dispersion plating coating (B). As wear progresses, the friction coefficient of the conventional dispersion plating film (B) increases, while the coefficient of friction of the film formed according to the present invention (A) remains constant. In addition, the change in the amount of wear was also observed in the product of the present invention (A) at the initial stage of operation.
The comparison product (B) also shows similar wear tendency. As the operating time elapses, the progress of wear in the product of the present invention (A) decreases, but the progress of wear in the comparative product (B) remains constant at the initial state.

After 100 hours of testing, the product of the present invention (A) was superior to the comparative product (B).
), the leveling wear is about 2/3, which means that it can be used for a longer period of time.

The reduction in wear of product A of the present invention is due to the wear of the plating layer containing only 1 μm hard particles on the surface layer and the 10 μm layer below it.
This is because the layer containing hard fine particles of m had higher wear resistance than the exposed layer.

(Effects of the invention) Since the product of the present invention has the above structure, wear resistance is improved,
This invention has excellent effects such as good familiarity and stable continuous operation over a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional structural diagram of the sliding part of a sliding member showing one embodiment of the present invention, and FIG. 2 is a comparison diagram of the coefficient of friction of the sliding member of the present invention product (A) and comparative product (B). FIG. 3 is a comparison diagram of the amount of wear. (1)... Base material, (2)... Hard fine particles with an average particle size of 10 μm, (3)... Average particle size 1
μm hard fine particles, (4) Nickel-phosphorus alloy, (5) Composite plating lower layer, (6) First
Figure 2: ν3 branching area Figure 3: Testing area

Claims (2)

[Claims] (1) In a sliding member in which a composite plating layer containing silicon carbide as a eutectoid and a nickel alloy as a matrix is provided on at least the sliding surface of a metallic base material, 1 μm or more and within 5 μm from the surface of the composite plating layer. The average particle size of silicon carbide in the upper layer is 0.2 μm to 3 μm, and the average particle size of silicon carbide in the subsequent lower composite plating layer is 0.2 μm to 3 μm.
It has a mixed layer in which particles of 3 μm and particles with an average particle size of 5 μm to 15 μm are mixed, and the surface roughness of the surface of the composite plating layer is set to a center line average roughness Ra of 0.2 μm or less. sliding member. (2) The sliding member according to claim 1, wherein the composite plating layer has a thickness of 8 μm to 35 μm.