JPH03186667A - Sliding member - Google Patents

Abstract

PURPOSE:To improve wearing resistance and initial conformability by providing an electroless nickel-phosphorus dispersed plating layer of specific hardness, dispersion-contained with silicon carbide of specific grain size by specific weight ratio, in a sliding surface and an electroless nickel-phosphorus plating layer of equal hardness in a surface of the electroless nickel-phosphorus dispersed plating layer and setting the surface roughness to not more than a specific value. CONSTITUTION:An electroless nickel-phosphorus dispersed plating layer 1 of HV 800 to 1,200 hardness, in which silicon carbide grains 4 of 0.2 to 3.0mu mean grain size are dispersedly contained 2 to 15% by weight ratio, is formed with a nickel-phosphorus alloy as matrix in surfaces of a metal base material 2. Next, an electroless nickel-phosphorus plating layer 5 of HV 800 to 1,200 hardness, not contained with silicon carbide, is formed in surfaces of the dispersed plating layer 1. Polishing work of lapping or the like is applied to a sliding surface of the nickel-phosphorus plating layer 5 with the surface roughness set to Ra0.2 or less. In this way, a sliding member, excellent in durability and wearing resistance and possible to maintain good initial conformability, can be obtained.

Description

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

(Prior Art and its Problems) Conventionally, piston rings that slide at high speed on cylinders or cylinder liners used in internal combustion engines of automobiles, motorcycles, etc. 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, there are problems in that the plating process takes a long time, and measures to prevent pollution caused by plating waste liquid are expensive, increasing the plating cost. 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

That is, the present invention provides plating hardness that contains 2% to 15% by weight of silicon carbide having an average particle size of 0.2μ to 3.0μ dispersed on at least the sliding surface of the metal base material constituting the sliding member. H
An electroless nickel/phosphorous dispersion plating layer with a matrix of nickel/phosphorus alloy of V800 to HV1200,
It has a two-layer plating layer with a silicon carbide-free electroless nickel phosphorus plating layer with a plating hardness of HV800 to HV1200 on its surface, and the surface roughness of the sliding surface is Ra 0.2μ or less. This problem has been solved by providing a sliding member characterized by having a plating layer formed thereon.

(Function) In the sliding member of the present invention, the outermost nickel-phosphorus plating layer has superior sliding properties and initial stain resistance than the lower dispersion plating layer, so that at the initial stage of operation, only the conventional dispersion plating layer is used. It has better initial stain resistance and stable initial performance than treated products.

Regarding wear resistance, since a good stain surface is formed between the mating material and the mating material at the initial stage of operation, the wear resistance is also improved. Next, the configuration of the present invention will be explained.

The sliding member of the present invention has a base material of steel, alloy, etc., and is coated with a nickel-phosphorus alloy (3) on the sliding surface of the base material (2) in an electroless nickel-phosphorus plating bath in which silicon carbide (1) is suspended. ) as a matrix and the above silicon carbide as a dispersion, forming a dispersion plating layer (4), and further applying an electroless nickel/phosphorous plating layer (5) that does not contain silicon carbide on the surface to form a two-layer structure. Form a plating layer. Next, heat treatment is performed in a heat treatment furnace at approximately 400"C for approximately 1 hour, thereby increasing the hardness of the plating layer to a high Vickers hardness of 1000 by crystallization of nickel and phosphorus, and at the same time, the dispersion. The adhesion between silicon carbide and the nickel-phosphorus alloy of the matrix is strengthened, and diffusion occurs at the boundary between the dispersion plating layer and the nickel-phosphorus plating layer, and the adhesion between both plating layers is also strengthened.

Furthermore, the surface of the outermost nickel-phosphorus plating layer is polished such as lapping to have a surface roughness of Ra 0.2μ.
The sliding member of the present invention is constructed by forming the following smooth surface.

An embodiment of the present invention will be described below based on the drawings.

(Example) As shown in the drawings, FIG. 1 is a cross-sectional structure diagram near the sliding surface of the sliding member of the present invention, and (1) is the base material (2) of carbon steel, alloy steel, cast iron, etc. Silicon carbide particles (4) uniformly dispersed in a nickel-phosphorus alloy layer (3) formed on the surface of
), and is constructed by further providing a nickel-phosphorous plating layer (5) on the surface of the above-mentioned dispersion plating layer. The average diameter of silicon carbide in the above-mentioned dispersed plating layer is preferably 0.2μ to 3.0μ; if it is finer than 0.2μ, wear resistance is poor, and if it exceeds 3.0μ,
Particles fall off quickly from the plating layer, resulting in poor wear resistance.

In addition, the content of silicon carbide in the dispersed menki in terms of weight ratio,
2% to 15%, but if it is less than 2%, sufficient wear resistance cannot be obtained, and if it exceeds 5%, the proportion of silicon carbide on the surface of the dispersed coating layer will increase, and the sliding property will deteriorate. to degrade. Further, it is desirable that the dispersion plating layer (4) has a thickness of 30μ or more, and the nickel-phosphorous plating layer (5) has a thickness of 3μ to 10μ.

The reason why the thickness of the dispersed plating layer is set to be 30 μm or more is because if it is less than 30 μm, the wear resistance is insufficient. In addition, the thickness of the nickel-phosphorus plating layer was set to 3μ to 10μ, but if it is less than 3μ, polishing such as lapping may be performed to reduce Ra 0.2.
In processing to obtain a smooth surface of less than μ, the thickness is
As a result, the plating layer having a two-layer structure, which is a feature of the present invention, cannot be formed. Moreover, if it exceeds lOμ, the nickel-phosphorus plating layer has inferior wear resistance than the dispersed plating layer, so that initial wear becomes large, which is not preferable.

The sliding properties of the coated sliding members obtained in the above examples were investigated using a vinyl-on-disc type abrasion tester.

The test pieces were a pin type test piece and a disk type test piece. (A) and a conventional dispersion plating film (B) were used.

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°C1 sliding speed 1.8m/sec
The lubricant is engine oil (SAE #20), and 1
A 00 hour wear test was conducted. The results of the test are as shown in Figures 2 and 3.
Compared to the conventional product (B), it was found that the coefficient of friction at the initial stage was lower, the amount of wear was also reduced, and it had excellent initial conformability and wear resistance.

(Effects of the Invention) As described above, the present invention has a nickel plated structure with a two-layer plating structure.
The crystallization of phosphorus increases the hardness of the Menki layer and at the same time strengthens its adhesion with silicon carbide, and the boundary layer is also strengthened by diffusion, resulting in a sliding member with excellent durability and wear resistance. Furthermore, since a smooth surface is formed by lapping the outermost layer, this invention has the advantage of maintaining good initial fit and wear resistance.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional structural diagram of the sliding part of a sliding member showing one embodiment of the present invention, FIG. 2 is a comparison diagram of the coefficient of friction between the sliding member of the present invention (A) and the conventional sliding member (B), and FIG. The figure is a comparison diagram of the amount of wear.

Claims (1)

[Claims] At least on the sliding surface of the metal base material, the average particle size is 0.2 μ to 3
．． An electroless nickel/phosphorus dispersion plating layer with a matrix of a nickel/phosphorus alloy with a hardness of HV800 to HV1200 containing silicon carbide of 0μ dispersed at 2% to 15% by weight, and a hardness on the surface of the dispersion plating layer. HV800～
It has a two-layer plating layer with an electroless nickel-phosphorus plating layer of HV1200, and the surface roughness of the sliding surface of the nickel-phosphorus plating layer is 0 in center line average roughness (Ra).
．． A sliding member characterized by being formed to have a thickness of 2μ or less.