JPH11158568A - Copper alloy excellent in wear resistance and sliding characteristics and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper alloy having wear resistance and excellent in slidability by mixing copper alloy powder with a specified amt. of ceramic powder of specified particle size previously coated with copper or the component the same as those in the copper alloy or the same alloy series and executing sintering. SOLUTION: Into copper alloy powder, ceramic particles previously coated with the components the same as those in the copper or the same alloy series or copper only by a sputtering method are dispersed. As for the ceramic particles, the particle size is regulated to <=10 μm. The coating layer of the components the same as those in the copper alloy or copper is applied so as to regulate the thickness to 0.1 to 3 μm. The dispersing ratio of the ceramic powder to the copper alloy powder is regulated to 5 to 30 vol.%. As the ceramic powder, diamond, boron nitride, sapphire, graphite, molybdenum disulfide, tungsten disulfide, silicon carbide and boron carbide are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in wear resistance and sliding properties of a copper alloy widely used as a sliding member for automobiles and industrial machines.

[0002]

2. Description of the Related Art Up to now, brass (copper-zinc alloy) and bronze (copper-tin alloy) have been used for sliding parts such as bearings of automobiles and industrial machines from the viewpoints of wear resistance, strength, corrosion resistance and formability. It has been widely used. However, in recent years, the demands for the miniaturization and high efficiency of the parts described above have been severe, and the wear resistance has been further improved.
There has been a demand for highly efficient sliding parts having a small coefficient of friction. In response to these demands, as a method of responding to the improvement of wear resistance, various additional elements have been added to conventional copper alloys to refine crystal grains, precipitation hardening, solid solution hardening, etc. Basically, when the wear resistance is improved by an alloy component, a decrease in the dynamic friction coefficient can hardly be expected, and it is very difficult to improve the slidability. Accordingly, if the wear resistance of these copper alloys is unnecessarily improved, the wear of the mating material increases, and as a result, the life of the entire machine cannot be extended.

[0003] While improving such mechanical properties,
In order to improve the slidability, it is necessary to rely on the use of a lubricant. As a result, the cost is increased and the use environment is restricted. In order to achieve both abrasion resistance and a reduction in the friction coefficient, which is a sliding property, it is effective to add ceramics, which are materials that have a low friction coefficient with respect to metals and plastics as sliding matrices and are themselves hard materials. It is. It is also effective to add graphite, molybdenum disulfide, tungsten disulfide, boron nitride or the like having self-lubricating properties.

[0004] However, when these ceramic particles are dispersed in a copper alloy, the wettability is poor and separation occurs, or oxidation or reaction with the matrix occurs during the sintering or casting process, resulting in an expected effect. It was difficult to get. For that purpose, surface treatment of ceramic particles is considered to be useful. However, electroplating or electroless plating of the particles cannot be applied unless the particle diameter is 100 μm or more, and thus cannot be applied to such sliding members. . Also, in these methods, it is necessary to pay great attention to environmental problems such as waste liquid.

[0005]

SUMMARY OF THE INVENTION In view of the above situation, the problem to be solved by the present invention is to use ceramic particles, which are expected to improve wear resistance and slidability, as a base material and a matrix. Another object of the present invention is to provide a production method in which a surface treatment is carried out with improved wettability or binding property, and these surface treatments can exert a sufficient effect. Another problem is that no environmental problem such as waste liquid occurs in the manufacturing process.

[0006]

In order to solve the above-mentioned problem, the present invention disperses, in a copper alloy powder, ceramic particles previously coated with the same component, the same alloy, or only copper by a sputtering method. At this time, the dispersion ratio of the ceramic powder to the copper alloy powder is set to 5 to 30% by volume. At this time, the crystallite diameter calculated by Scherrer's formula from the half width of the peak intensity of the X-ray diffraction of the surface coating layer is 30.
When the thickness is 0 nm or less, the wettability with the copper alloy as the matrix is excellent and the bonding strength is excellent. Further, the sintering method uses a discharge plasma method, and the holding time at 500 ° C. or more in the sintering process is set to 10 minutes or less to suppress excessive diffusion between the surface coating layer and the matrix layer, and It has been found that, in addition to maintaining the affinity for, the oxidation and thermal decomposition of the dispersed particles can be suppressed, and as a result, a copper alloy having excellent wear resistance and sliding properties can be obtained.

[0007]

In the copper alloy of the present invention, the ceramic particles to be dispersed are hard and contribute to the improvement of wear resistance and have a low coefficient of friction with respect to mainly iron-based materials such as steel and tool steel. Specifically, diamond, boron nitride, sapphire, graphite, molybdenum disulfide, tungsten disulfide,
Silicon carbide and boron carbide. These ceramic particles need to have a particle size of 10 μm or less. When the particle size exceeds 10 μm, unevenness in slidability occurs, and as a result, the life is shortened. A coating layer of the same component or copper as the copper alloy dispersed in these ceramic particles having a thickness of 0.1 to 0.1
It is applied to be 3 μm. At this time, if the thickness of the coating layer is
If it is less than 1 μm, there is a possibility that it will be released during dispersion or sintering, or will be missing after sintering. If it exceeds 3 μm,
The internal stress of the coating film increases, and peeling of the surface film occurs. At this time, the shape of the powder to be coated is not particularly limited, but it is preferable to use a spherical powder in order to reduce the variation in the binding property with the matrix. It is also desirable that the particle size is about 0.1 to 1 μm.

[0008] As a method of coating the ceramic particles, a sputtering method is desirable from the viewpoint of suppressing the thermal influence of the base material, further densifying the coating state, coating the alloy components, and the like. As a method of coating particles by sputtering, for example, Japanese Patent Application Laid-Open No.
According to the publication No. 53068, this is possible. Specifically, coating can be performed by putting predetermined powder into a rotating barrel and applying vapor-deposited particles or sputtered particles with stirring.

Further, it is necessary for the surface layer film to have a crystallite diameter of 300 nm or less, as described in the claims. If the crystallite diameter is larger than this, film peeling is likely to occur, and sufficient wettability and bondability with the matrix may not be ensured even in the film thickness of the claims, or variation between particles may increase. There is. If the crystallite diameter becomes smaller (crystal grains become finer), slip occurs due to crystal grain boundaries, so that it has sufficient deformability to reduce the thermal stress generated between the base material particles and the surface metal layer. The present inventors have found that a crystallite diameter sufficient for this purpose needs to be 300 nm or less as a crystallite diameter calculated from Scherrer's formula.

The crystallite diameter according to Scherrer's equation described herein is calculated by the following equation. D = k × λ / β × cos θ D: crystallite diameter (angstrom) k: constant (= 0.9 where measured X-ray is Cu Kα
Λ: wavelength of the measured X-ray (angstrom) β: spread of the diffraction line (half width) (radian) θ: Bragg angle of the diffraction line (radian).

The crystallite diameter of the conductive layer can be reduced by reducing the deposition rate and the temperature of the substrate. Specifically, as a guide of the deposition rate, the amount of metal coating per 1 g of resin particles is 0.01 g.
/ hr, and the temperature of the substrate is preferably 200 ° C. or less.

Next, the copper alloy powder and the surface-coated ceramic particles are mixed and sintered. In this case, as a sintering method, a discharge plasma sintering method which can suppress the influence of heat and has an effect of cleaning the oxide film on the particle surface is preferable. At this time, the time during which the temperature is maintained at 500 ° C. or more is set to 10 minutes or less. If the time is maintained for more than this time, oxidation may occur depending on the ceramic particles, and thermal decomposition and phase transformation may be a concern. Moreover, as a result of excessive diffusion of the metal layer on the surface of the ceramic particles into the matrix, the bonding force with the ceramic particles is reduced, and as a result, particles may be missing. The matrix copper alloy powder is desirably about 20 to 100 μm from the viewpoint of dispersibility, oxidation, and the like.

The metal-coated ceramic particles produced in this manner are easily sintered and dispersed with the copper alloy as the matrix. There is no change in characteristics. Therefore, it is possible to reduce the coefficient of friction as slidability and improve the wear resistance. Further, wastewater treatment is not required due to simplification of the process, and furthermore, as a result of suppressing the amount of coating, the cost can be reduced and industrial use is extremely large.

[0014]

EXAMPLES Example 1 Various metal-coated ceramics were dispersed in various copper alloy powders having an average particle size of 50 μm and sintered. For this sintering, a spark plasma sintering method is used.
The conditions are as follows: the sintering temperature is set to the melting point (absolute temperature) of the copper alloy.
8 to 0.9, the sintering time is 5 minutes, and the sintering pressure is 10
It was set to 0 MPa. The abrasion resistance of the sintered body was evaluated by the amount of abrasion when the cylinder was slid at a sliding speed of 1 m / min for 30 minutes at a pressure of 1 MPa on a cylindrical SiC grinding wheel. The atmosphere at the time of evaluation was dry in the air. The evaluation criterion was based on the evaluation that the ceramic particles were not dispersed, and those having a wear amount of 0.1 times or less, that is, those having a wear resistance of 10 times or more were obtained.極 め て as extremely excellent in ○, similarly ３ as 3 to 10 times or less as excellent in wear resistance, を as 1 or more to less than 3 as no improvement in abrasion resistance, 見 as 1 or less Indicates that the wear resistance is deteriorated, and is evaluated as x.

Next, a dynamic friction coefficient was measured and evaluated as a sliding characteristic. The evaluation method uses a pin-on-disc device, the partner material is a spherical material of carbon steel for machine structure (equivalent to S45C of JIS G 4051), a pressure of 9.8 N, a sliding speed of 1 m / min, dry type, in the air Done. At this time, when the coefficient of kinetic friction was 0.1 or less, it was determined that the slidability was particularly excellent,
A larger value of 0.25 or less is considered excellent in slidability,
When the value was greater than 0.25 and 0.5 or less, the slidability was not improved, and when the value was greater than 0.5, the slidability was degraded. Tables 1 and 2 summarize these results. In addition, similarly, a sintered material and a material produced by a coating method other than the claims were used as comparative materials for the surface metal, film thickness, ceramic particle diameter, etc. other than the claims.

[0016]

[Table 1]

[0017]

[Table 2]

From these results, it can be seen that the materials within the scope of the present invention are evaluated as ○ or と も に in both abrasion resistance and sliding characteristics. As a coating method, a sputtering method capable of coating an alloy over a wide composition is desirable.

Example 2 Various thicknesses of copper and JI were formed by sputtering on boron nitride particles having an average particle size of 5 μm.
A coating equivalent to SH 2203 Class 1 bronze alloy was applied, mixed with 10% by volume of the same bronze alloy powder (average particle size: 50 μm), and fired by discharge plasma at a temperature of 0.8 times the melting point (absolute temperature). Tied. The sintering time is 3 minutes. At this time, the film thickness, wear resistance and sliding characteristics were evaluated in the same manner as in Example 1. In addition, the crystallite diameter of these coating layers was 50 to 200 nm. FIG. 1 shows the evaluation results. From these results, it is understood that the suitable coating thickness of the surface metal layer is 0.1 to 3 μm. It can also be seen that the characteristics are particularly excellent when the coating thickness is 0.5 to 1 μm.

Example 3 Diamond particles having various average particle diameters were sputtered to a thickness of 0.5 μm.
A coating equivalent to Class 1 bronze alloy of JIS H 2203, 15% by volume was mixed with the same bronze alloy powder (average particle size: 30 μm), and spark plasma sintered at a temperature of 0.75 times the melting point. . The sintering time is 4 minutes. At this time, the average particle size, abrasion resistance and sliding characteristics were evaluated in the same manner as in Example 1.
The crystallite diameter of these coating layers was 60 to 300 nm. FIG. 2 shows the evaluation results. From this result, it is understood that the average particle diameter of the dispersed ceramic particles is suitably 10 μm. In addition, it can be seen that the characteristics are particularly excellent when the average particle diameter is 0.5 to 5 μm.

Example 4 Sapphire particles having an average particle diameter of 10 μm were subjected to a sputtering method to form a JIS H film having a thickness of 0.2 μm.
Coating equivalent to 2202 type 1 brass alloy was applied, mixed with the same brass alloy powder (average particle size: 30 μm) in various volume percentages, and spark plasma sintered at a temperature of 0.8 times the melting point. The sintering time is 2 minutes. At this time, the dispersion ratio of ceramic particles, abrasion resistance and sliding characteristics were evaluated in the same manner as in Example 1. The crystallite diameter of these coating layers is 60 to 15
It was 0 nm. FIG. 3 shows the evaluation results. From these results, the ratio of the dispersed ceramic particles was 5 to 30% by volume.
Is suitable. Also, especially when the volume fraction is 10
It can also be seen that the characteristics are excellent at 20% by volume.

Example 5 Tungsten disulfide particles having an average particle size of 1.5 μm were formed to a thickness of 3 μm by sputtering.
JIS H 2202 Class 1 brass alloy equivalent or pure copper coating, this is the same brass alloy powder (average particle size: 50 μm)
And sintered by spark plasma at a temperature of 0.85 times the melting point. The sintering time is 2 minutes. At this time,
The crystallite diameter of the coating layer was changed by changing the coating conditions to change the crystallite diameter of the coating layer, and the changes in wear resistance and sliding characteristics due to this were evaluated in the same manner as in Example 1. FIG. 4 shows the evaluation results. From this result, it is also understood that the characteristics are excellent when the crystallite diameter of the coating layer is 300 nm or less.

Example 6 A molybdenum disulfide particle having an average particle size of 0.5 μm and a diamond particle having an average particle size of 6 μm were sputtered on a JIS H 220 film having a thickness of 0.1 μm.
2 was coated with a brass alloy equivalent to Class 1 brass alloy, mixed with the same brass alloy powder (average particle size: 50 μm) at 20% by volume, and spark plasma sintered at a temperature 0.9 times the melting point. At this time,
The time during which the temperature was maintained at 500 ° C. or higher was changed. In addition, the crystallite diameter of the coating layer was 200 nm or less. 500
FIG. 5 shows the results of examining the change in the abrasion resistance and the sliding characteristics evaluated by the same method as in Example 1 and the holding time at a temperature of not less than ° C. From this result, it is also understood that the characteristics are excellent if the holding time at 500 ° C. or more is within 10 minutes. Particularly, good characteristics are exhibited in 3 to 9 minutes.

[0024]

As described above, according to the present invention, a copper alloy having abrasion resistance and excellent sliding characteristics can be provided, and high efficiency and miniaturization of automobiles, industrial machine parts and the like can be provided. Contribution is extremely large.

[Brief description of the drawings]

FIG. 1 is a summary of evaluations of Example 2.

FIG. 2 is a summary of evaluations of Example 3.

FIG. 3 is a summary of evaluations of Example 4.

FIG. 4 is a summary of evaluations of Example 5.

FIG. 5 is a summary of evaluations of Example 6.

Claims (4)

[Claims] 1. The method according to claim 1, wherein the copper alloy powder has a thickness of 0.1 to
3 μm copper or a ceramic powder coated with the same component or the same alloy system as the copper alloy and having a particle size of 10 μm or less,
A copper alloy having excellent wear resistance and sliding characteristics, characterized by being mixed and sintered at 5 to 30% by volume. 2. Abrasion resistance and sliding characteristics according to claim 1, wherein diamond particles, boron nitride, sapphire, graphite, molybdenum disulfide, tungsten disulfide, silicon carbide, and boron carbide are used as the ceramic particles. Excellent copper alloy. 3. A method for coating the ceramic particles according to claim 1 or 2 with copper or the copper alloy, wherein a physical vapor deposition method is used, and X of the coated metal layer is coated.
A copper alloy having excellent wear resistance and slidability, wherein the crystallite diameter calculated from the half width of a line diffraction peak by the Scherrer's formula is 300 nm or less. 4. The sintering of the powder mixture according to claim 1, wherein the sintering process is performed at a temperature of 500 ° C. or more for 10 minutes or less. Manufacturing method of copper alloy with excellent mobility.