JPS6321076B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Field of Industrial Application This invention is applicable to metal contact surfaces such as rolling surfaces of various rolling parts such as rolling bearings, ball screws, and ball joints, and sliding surfaces of various sliding parts such as sliding bearings. The present invention relates to a method for lubricating a metal contact surface by forming a self-lubricating dispersed plating film in which a solid lubricant is dispersed in a metal matrix. (b) Conventional technology For example, methods of lubricating the rolling surfaces of rolling bearings, ball screws, ball joints, etc. include applying oil or grease.Electroplating or electroless plating of metals with solid lubricating properties such as gold and silver. Coating by wet plating such as Coating the same metal as above by ion plating Applying a solid lubricant such as molybdenum disulfide (MoS ₂ ) together with a synthetic resin binder and baking Same as above Coating with a solid lubricant by sputtering is used. However, the conventional methods of lubricating rolling surfaces described above each have the following drawbacks. That is,
In this case, the evaporation rate of oil or grease is high in a vacuum, so it is often unusable, and the grease, etc. deteriorates due to radiation. next,
In this case, the lubricity varies greatly due to impurities and dirt mixed into the plating film, making it unreliable. Next, in the case of , the processing temperature is as high as 300 to 600°C, so the materials that can be processed are limited. for example,
In the case of bearing steel type 2 (SUJ-2), which is the most common rolling bearing material, the tempering temperature is around 180°C, so dimensional changes occur during processing. Furthermore, processing equipment is expensive, and it is difficult to uniformly coat bearings with complex shapes. Then, if
In a vacuum, gas is released from the binder, which contaminates the inside of the vacuum device and causes deterioration of the film. Furthermore, in a radiation environment, the binder deteriorates due to radiation, resulting in peeling of the film or falling off of the solid lubricant. In the final stage, the adhesion strength between the substrate and the coating is low, making it easy to peel off. Therefore, in order to solve the above-mentioned drawbacks, progress is being made in the development of a lubrication method that forms a self-lubricating dispersed plating film in which a solid lubricant is dispersed in a metal matrix. This type of lubrication method was published in Japanese Patent Application Laid-Open No. 1986-
This method is disclosed in Japanese Patent Publication No. 75598 and Japanese Patent Application Laid-open No. 105500/1983. That is, these have a self-lubricating dispersed plating film formed on the sliding surface in which a solid lubricant such as boron nitride (BN) or molybdenum disulfide (MoS ₂ ) is dispersed in a nickel matrix. By the way, in order for the dispersed plating film to fully perform its function, the solid lubricant particles must be co-deposited into the metal matrix to the extent that they affect friction and wear. In the case, the experimental data shows that the eutectoid amount of BN particles is 8.6vol%
It wasn't enough. Furthermore, in the case of MoS ₂ , it was difficult to eutectoid because it showed almost no wettability to the plating solution and it was difficult to uniformly disperse it in the plating solution. Therefore, in order to obtain a Ni-MoS ₂ dispersed plating film, the plating solution and MoS ₂ are pre-stirred in a blender at 1800 rpm, and then the dispersion plating is performed while circulating the plating solution with a pump at 20/min. The eutectoid amount of the _two particles varies greatly, ranging from 15 to 88 vol%, and the resulting plating film contains MoS ₂
Agglomeration of particles was observed, and the film had weak adhesion and was easily peeled off. Therefore, this cannot withstand the rolling surfaces of various rolling parts such as rolling bearings, ball screws, and ball joints. (c) Purpose of the Invention This invention provides a method for lubricating a contact surface to obtain a self-lubricating dispersed plating film with adhesiveness and wear resistance that can withstand rolling by highly eutectoid and uniformly dispersing a solid lubricant in a metal matrix. The purpose is to provide the following. (d) Structure of the Invention This invention involves stirring in a circulating manner a plating liquid prepared by dispersing graphite as a solid lubricant in a nickel bath and further adding a cationic hydrocarbon surfactant as a surfactant. A self-lubricating dispersion is created in which nickel and graphite are simultaneously precipitated on the surface of the workpiece by immersing the anode metal and the cathode workpiece, on which a nickel strike has been previously applied, in this plating solution and electrolyzing the workpiece. The gist of this paper is a method of lubricating the contact surfaces that form the plating film. According to this invention, graphite, which is a solid lubricant, can be co-deposited in a nickel matrix at a maximum of about 56 vol%. As the plating solution of this invention, Wat bath nickel plating solution is used. The composition of Watsuto bath nickel sulfate liquid is 200% nickel sulfate.
~400g/, nickel chloride 40-50g/, boric acid
It is 20-40g/. Graphite is pretreated for the purposes of removing oil, dissolving metals attached to graphite with nitric acid, and separating (filtering) water and solids (graphite) when plating this Wat bath nickel plating solution. Distribute. In order to uniformly disperse graphite in the Watts bath nickel liquid and to simultaneously precipitate graphite and nickel, it is necessary to prevent the graphite from agglomerating and to give it a positive charge. Therefore, in order to give the graphite wettability to the plating liquid, 0.1 to 10 g of a cationic hydrocarbon surfactant is added and stirred in a circulating manner. Satisfies the above conditions, current density 1 to 10 A/dm ² ,
When electrolysis is performed using pure nickel for the anode and a treated material that has been previously given a nickel strike for the cathode under electrolytic conditions at a temperature of 20 to 60℃ and a pH of 0.1 to 6, graphite is formed in the nickel matrix on the cathode. A nickel-graphite dispersed plating film was formed. According to this invention, graphite is highly eutectoid and uniformly dispersed in the nickel matrix,
A self-lubricating dispersed plating film with good adhesion and wear resistance is formed. Next, the effects of this invention will be explained according to examples. (E) Example Dispersion plating was performed on rolling parts using the plating liquid composition and plating conditions as shown below. Gamma plating liquid composition: Nickel sulfate 240g / Nickel chloride 45g / Boric acid 30g / Surfactant (cetyltrimethylammonium chloride) 0.2g / Graphite 110g / This plating liquid is uniformly stirred in a circulating system. Γ plating conditions PH PH5 Plating liquid temperature 30℃ Cathode current density 5A/dm ² , 1A/dm ² Plating time 5 min, 25 min Also, since the adhesion is insufficient with the above dispersion plating alone, please do the following before dispersion plating. Perform nickel strike on rolling parts in advance using appropriate liquid composition and plating conditions. Γ solution composition Nickel chloride 120g / hydrochloric acid 60ml / Γ plating conditions Plating solution temperature Room temperature cathode current density 3.5A/dm ² Plating time 2.5 min The dispersion plated film obtained under the above conditions is as follows:
Approximately 50 vol% of graphite is uniformly dispersed and eutectoid in the nickel matrix. The rolling parts thus formed were subjected to an operational test using the testing apparatus shown in the drawings. In the drawing, 1 is test bearing #6200, 2 and 3 are support bearings,
4 is the shaft and 5 is the ball. That is, the inner and outer rings of the test bearing #62001 were plated with 5 μm nickel-graphite dispersion plating, and the shaft 4 was driven by a belt and subjected to a thrust load of 6 kg・f as shown in the drawing.
Rotated at 30.000rpm. The test conditions were no oil, one cycle was 10 min, and this was repeated for a maximum of 10 cycles until torque fluctuation (reduction in rotational speed) occurred. As a comparative test, bearings were coated with baked molybdenum disulfide, porous chrome plating (plating thickness: 10 μm), bearings impregnated with graphite, and electroless gold plating (plating thickness:
0.4 μm) was included in the operational test. The performance test results are shown in Table 1.

【table】

[Table] As shown in Table 1, the bearings coated with nickel-graphite dispersion plating showed overwhelmingly superior durability compared to other surface-treated bearings. In addition, after this performance test, these bearings were disassembled and the raceway surfaces were observed under a microscope. As a result, no peeling of the plating film or abnormal wear was observed in the dispersion-plated bearings, but other surface-treated bearings showed no peeling of the plating film or abnormal wear. Peeling of the plating and abnormal wear were observed. Incidentally, although the above explanation deals with rolling surfaces, it goes without saying that similar results can be obtained with respect to sliding surfaces. (f) Effect of the invention According to the invention, since graphite is dispersed as a solid lubricant and a cationic hydrocarbon surfactant is added as a surfactant, the solid lubricant can be highly eutectoid in the metal matrix. Moreover, it can be uniformly dispersed, and the lubricity and wear resistance can be improved. In addition, since nickel strike is performed in advance before dispersion plating, adhesion that can withstand rolling is obtained, increasing the life of various rolling parts such as rolling bearings, ball screws, and ball joints.

[Brief explanation of the drawing]

The drawing is a schematic diagram of an apparatus for testing the performance of the metal contact surface lubrication method of the present invention.

Claims (1)

[Claims] 1 A plating solution prepared by dispersing graphite as a solid lubricant in a nickel bath and adding a cationic hydrocarbon surfactant as a surfactant is stirred in a circulating manner, and an anode is placed in the plating solution. It is characterized by forming a self-lubricating dispersed plating film on the surface of the workpiece in which nickel and graphite are simultaneously precipitated by immersing the metal and the workpiece, which is the cathode, on which a nickel strike has been applied in advance, and electrolyzing the workpiece. How to lubricate metal contact surfaces.