JPS6051549B2 - thermal spray material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal spray material, and more particularly to a thermal spray material for applying a layer with different properties to the surface of a workpiece.

Thermal spraying is one method for applying a layer with properties different from those of the workpiece to the surface of the workpiece, such as structures and machinery.

This is because the material with different properties from the workpiece is exposed to oxygen.
It is melted using a chemical combustion flame such as an acetylene flame or an oxygen-hydrogen flame, or electric energy such as an electric arc or a plasma jet, and is sprayed onto the workpiece as fine particles in the form of a spray to form a coating layer. The thermal spraying material used is one that enhances rust prevention, corrosion resistance, wear resistance, seizure resistance, heat resistance, etc. In general, coatings made by thermal spraying are rapidly solidified by thermal spraying, and therefore have properties that are significantly different from melted materials with the same components. Even with the same composition, thermal sprayed coatings have higher hardness than cast lumber. In addition, the presence of pores in the coating provides lubricity and generally improves wear resistance. In particular, thermal spray materials for imparting wear resistance include metal materials and non-metal materials.

Metal materials include steel, cast iron, aluminum-silicon alloys, aluminum or aluminum alloys, copper or copper alloys, self-fusing alloys, cemented carbide, etc., and these are used depending on operating conditions or friction conditions. , as shown below, has both advantages and disadvantages. First of all, regarding steel, this thermal spray layer partially becomes martensite due to thermal spraying, so it becomes hard and has high wear resistance.

However, this coating is brittle and has low seizure resistance, so there are limits to its application to parts that can further improve wear resistance.
A self-fusing alloy is a nickel- or cobalt-based alloy with boron and silicon added to form a eutectic alloy, which has a fluxing effect, and also has high adhesion because the coating is heated above its melting point after thermal spraying. This coating has various hard intermetallic compounds and has high wear resistance, but the coating is brittle due to the action of boron, and there are problems in terms of galling resistance and compatibility with mating materials on sliding surfaces. Since cemented carbide with high wear resistance is generally a high melting point material, coating is performed by plasma spraying. This coating is extremely hard;
Due to its high wear resistance, it is often used in mechanical seals and sliding parts of molds. However, although this coating has high wear resistance, it is hard and brittle and requires a long time for finishing, so it is limited to special uses. Coatings made of aluminum and copper alloys are soft and have good conformability due to partial plastic flow on sliding surfaces, and are also tough and have excellent finishing workability, so they are sometimes used on friction surfaces, but they are not wear resistant. However, there are problems in terms of seizure resistance, especially in areas where oil runs out. On the other hand, ceramic materials are used as non-metallic thermal spraying materials, and the coating obtained by thermal spraying ceramic materials is extremely hard and has high wear resistance, so it is suitable for mechanical seals and sliding parts of molds. It is widely used.

However, when a ceramic material or a non-metallic powder such as molybdenum disulfide is used as the thermal spray material to form a thermal spray layer, there is a drawback that the adhesion of the thermal spray layer is extremely low.

Further, even when these nonmetallic powders and metal powders are simply mixed, the adhesion of the sprayed layer is low. In other words, these nonmetallic powders generally have a significantly uneven surface, and therefore a large amount of adsorbed gas is absorbed.According to the study by the present inventors, this adsorbed gas increases the bonding force between metal powders or nonmetals during thermal spraying. It became clear that the The purpose of the present invention is to improve the above-mentioned drawbacks of the prior art and improve wear resistance, adhesion, galling resistance, and self-lubrication. The object of the present invention is to provide a thermal spraying material that has excellent properties such as properties and is suitable for obtaining sliding members and the like.

The gist of the present invention resides in a thermal spray material characterized by comprising metal powder and molybdenum disulfide powder coated with metal.

Examples of the metal powder include the above-mentioned metallic thermal spray materials, ie, steel, cast iron, aluminum-silicon alloy, aluminum or aluminum alloy, copper or copper alloy, self-fusing alloy, cemented carbide, and the like.

Further, the coating metal for coating molybdenum disulfide is preferably one that forms a solid solution with the metal powder or is metallically bonded to the metal powder through eutectic or the like, and further has a similar hardness.

As such a coating metal, one having the same composition as the metal powder or the same as the main component of the metal powder can be used, and a metal having a different composition from the metal powder can also be used. In the present invention, molybdenum disulfide and the coating metal must not react with each other or be compatible with each other. This is because if the two react or become compatible, the properties of molybdenum disulfide cannot be utilized. Therefore, the above considerations must be taken when selecting the coating metal. The coating metal surrounds the molybdenum disulfide, and the molybdenum disulfide is uniformly dispersed by thermal spraying, and the coating metal is alloyed with itself, the workpiece, and the metal powder, resulting in strong adhesion and durability. A thermally sprayed layer with excellent wear resistance, anti-galling properties, self-lubricating properties, etc. can be obtained.

The coating of molybdenum disulfide with the coating metal is preferably carried out by chemical plating.

This is because coating by chemical plating can drive out the gas adsorbed on the surface of molybdenum disulfide, and by thermal spraying, it is possible to obtain a thermally sprayed layer with high adhesion and no pores. be. That is, the present inventors have found that when gas is adsorbed in molybdenum disulfide, the adsorbed gas expands during thermal spraying, which causes pores to be formed in the thermal sprayed layer. In order to firmly adhere the metal-coated molybdenum disulfide to the surface of the material to be thermally sprayed, at least a part of the surface of the thermal spray particles is melted in a heat source, and the particles are flown onto the surface of the material to be thermally sprayed, and their kinetic energy is used to flatten them. , it is necessary to make it expand. Molybdenum disulfide burns when mixed with oxygen and does not form a solid solution with the base material. According to the conventional method, molybdenum disulfide powder is mechanically mixed directly into the base material and then thermally sprayed. Molybdenum disulfide scatters on the surface and hardly remains in the coating. Furthermore, even if molybdenum disulfide is included, it will inevitably adhere to the oxygen gas that comes into the thermal spray heat source from the atmosphere while burning, so there will be spaces between it and the base material, resulting in an extremely fragile coating and sliding. It is unsuitable as a material. Generally, a certain degree of strength or compressive strength is required for application as a sliding member. The present inventors have found that the most preferred embodiment of the thermal spraying material of the present invention is that it is composed of copper or copper-based alloy powder and molybdenum disulfide powder coated with copper or copper-based alloy, and that the material is formed as a base on the surface of molybdenum disulfide. By chemically plating copper or copper-based alloys with copper or copper-based alloys that have solid solubility limits, and then mixing this with base copper or copper-based alloy powder and thermal spraying, it is possible to improve wear resistance, adhesion, It has been found that a thermal sprayed layer with particularly excellent galling resistance and self-lubricating properties can be obtained.
The particle size of molybdenum disulfide affects the workability of thermal spraying and the uniformity in the coating, so it is preferably 5 to 100 pm, preferably 20 to 74 pm. During chemical plating, particles with a diameter of 5 μm or more are preferable in order to prevent them from floating in the plating solution and to form plating with a uniform thickness on the surface of each particle. When molybdenum disulfide plated with copper or copper-based alloys is thermally sprayed,
The metal part on the surface melts and reacts with the base to form a strong bond.
The molybdenum disulfide portion remains intact even though it is flattened. On the other hand, since the base copper or copper-based alloy is melted and sprayed, the surface of the material to be thermally sprayed becomes largely flattened. Therefore, the particle size of the copper-coated molybdenum disulfide is preferably 100 pm or less in order to form a dense sprayed layer. The thickness of the plating film is 1
-70 pm (preferably 5-10 pm) is good. That is, if the thickness is 1 μm or more, it is possible to prevent the molten copper plating film from agglomerating due to surface tension during thermal spraying, thereby preventing part of the molybdenum disulfide from being exposed and not being tightly adhered. Further, from the viewpoint of ensuring the necessary amount of molybdenum disulfide and wear resistance, the thickness is preferably 70 μm or less. The amount of molybdenum disulfide coated with copper as a wear-resistant sliding part is preferably 5% by volume or more to prevent a decrease in wear resistance. In addition, as the amount of molybdenum disulfide increases, the wear resistance and seizure resistance improve, but in order to obtain a coating with high adhesion, it is recommended that the amount of molybdenum disulfide coated with copper be 7% by volume or less. good. In addition, when copper-coated molybdenum disulfide powder, which is made by chemically plating copper or a copper-based alloy on the surface of molybdenum disulfide, is dispersed and cast into copper or copper-based alloy, when oxygen mixes with the copper-coated molybdenum disulfide, the dispersion occurs. Alternatively, molybdenum disulfide is burned, leaving almost no molybdenum disulfide, but by thermal spraying copper-coated molybdenum disulfide powder, which is copper-plated molybdenum disulfide, mixed with copper or copper-based alloy powder, It has become clear that molybdenum disulfide can be firmly adhered to the sprayed layer.

The present invention will be further explained below with reference to Examples.

Example 1 Copper was coated with a particle size of 5 μm by electroless chemical plating on copper-based alloy powder (11% by weight aluminum, balance copper) with a particle size of 37 to 78 μm and molybdenum disulfide powder with a particle size of 44 to 78 μm.
powder coated to a thickness of 0,5,10,20,
The powder obtained by mixing to give a volume% of 30, 40, 50, 60, 7% by volume was made into a circle with a diameter of 25 TWL by the oxygen-acetylene method, the oxygen-hydrogen method, and the plasma method (400A (7) Ar, N2 plasma). Rod end face and thickness 30wn18h17
? Thermal spraying was applied to the mild steel surface.

After roughening the surface to be sprayed by grit blasting,
Preheated to 50°C. The spray thickness is approximately 0.7WL.
FIG. 1 is a diagram showing the results of measuring the adhesion of a thermally sprayed layer of a material coated with copper plating and thermally sprayed using molybdenum disulfide.

The adhesion strength decreased as the amount of copper-coated molybdenum disulfide increased, but it showed a high value of about 100 kg/d even when the amount of copper-coated molybdenum disulfide was 70% by volume. Comparative Example 1 A mixture of the same copper-based alloy powder as in Example 1 and molybdenum disulfide powder without plating coating (molybdenum disulfide amount 20
, 40 and 6 volume %), but in all cases, the molybdenum disulfide powder was oxidized and almost completely disappeared, and no adhesion of molybdenum disulfide was observed.

Example 2 5 μm of nickel was applied to 37-78 μm copper-based alloy powder (aluminum 11 weight ('n%, balance copper) and 44-78 μm molybdenum disulfide powder by electroless plating).
powder coated to a thickness of m, the latter being 0,5,10,20
The powder obtained by mixing the powder to give a volume% of Round bar end face and thickness 30TWL, 8-,
It was sprayed onto the mild steel surface of 7 gourds.

After the surface to be thermally sprayed is roughened by grit blasting,
Preheated to 150°C. The sprayed layer thickness is approximately 0.7Wr! n
It is. Figure 2 shows the thermal sprayed layers sprayed on mild steel plates in Examples 1 and 2 and Comparative Example 1, which were finished to JIS standard 0.5S by machining and lapping, and then subjected to wear resistance tests using the Ohkoshi abrasion test method. It is a diagram showing the results obtained. a and b were produced in Example 1, c was produced in Example 2
and d are those manufactured in Comparative Example 1 without a blind coating. A, c and d are friction speeds 2.0
77! ．． /sec and b is the friction speed 0.67TL. /second data. The material used for the wear test is JIS standard SU.
J2 bearing steel (hardness 800-850HV). The friction distance is 200rr], the load is 18.9k9, and the lubricant is turbine oil. As shown in the figure, the wear resistance of the material sprayed using the thermal spraying material of the present invention increases significantly as the amount of molybdenum disulfide coated with copper increases.

In particular, it can be seen that the mixture (a) in which copper-based alloy powder is mixed with copper-plated molybdenum disulfide has significantly better wear resistance than the mixture (c) in which nickel-plated molybdenum disulfide is mixed. However, those without plating coating (d
), almost no molybdenum disulfide remains in the sprayed layer.
Therefore, when the amount of molybdenum disulfide in the thermal spray material is increased, the wear resistance tends to decrease. As mentioned above,
The excellent abrasion resistance of the thermal sprayed layer obtained using the thermal spraying material of the present invention is due to the fact that it contains molybdenum disulfide, but it is also thought to be due to its high adhesion.

FIG. 3 is a 10@ micrograph of the thermally sprayed layer produced in Example 1 with an amount of molybdenum disulfide of 4% by volume.

The sprayed layer had almost no pores and was formed in close contact with the material to be sprayed. As described above, the present invention provides a thermal spraying material that has excellent wear resistance, adhesion, galling resistance, self-lubricity, etc. and is suitable for obtaining sliding members and the like.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the adhesion of a thermally sprayed layer using plating-coated molybdenum disulfide and the amount of copper-coated molybdenum disulfide, and Figure 2 is a diagram showing the relationship between the specific wear amount and (copper-coated) disulfide. A diagram showing the relationship with the amount of molybdenum and FIG. 3 are micrographs of a sprayed layer obtained using the sprayed material of the present invention.

Claims (1)

[Scope of Claims] 1. A thermal spray material comprising metal powder and molybdenum disulfide powder coated with metal. 2. The metal for coating molybdenum disulfide is a material that is dissolved in solid solution or metallically combined with the metal powder,
The thermal spray material according to claim 1, which is a material that is neither reactive nor compatible with molybdenum disulfide. 3. The thermal spray material according to claim 1, wherein the metal powder is copper or copper-based alloy powder, and the metal coating molybdenum disulfide is copper or copper-based alloy.