JPS5810986B2 - sliding member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sliding member with excellent seizure resistance.

In recent years, due to the demand for lower fuel consumption in automobiles, the friction area of various sliding parts such as shift fork pawls, inner surfaces of cylinder liners, piston rings, inner surfaces of synchronizer rings, and transmission friction plates has been reduced in order to reduce friction loss. In addition, efforts are being made to reduce the viscosity of lubricating oil.

However, this makes it difficult for an oil film to form on each sliding part, causing seizure and abnormal wear. Therefore, it is necessary to improve the performance of sliding parts, especially seizure resistance and wear resistance, more than ever before. In some cases, conventional products cannot be used.

For example, if we look at the shift fork among sliding members,
Conventionally used claw treatment methods such as induction hardening, hard chrome plating, and aluminum bronze spraying have caused the above-mentioned problems.

Further, molybdenum (Mo 2 ) thermal spraying is a good treatment method with excellent seizure resistance and wear resistance, but it is very expensive and has resource problems, so it cannot be used with full satisfaction.

The present invention is intended to solve the above problems, and uses inexpensive and particularly low viscosity oil, and has excellent seizure resistance and
The present invention provides a sliding member that exhibits wear resistance.

The sliding member of the present invention has 2 to 3
It is characterized by providing a sprayed layer consisting of 0% by weight of molybdenum and the remainder aluminum alloy or copper alloy.

The aluminum alloy used in the present invention includes Al-
8i alloy or A7-Pb alloy, and hypereutectic Al-8i alloy is particularly preferred.

Further, as the copper alloy, an aluminum bronze alloy or a phosphor bronze alloy is used, and an aluminum bronze alloy is particularly preferred.

Thermal spraying may be performed by separately supplying the aluminum alloy, copper alloy, and Mo as matrix materials to the thermal spraying device and spraying them simultaneously to form the desired thermal spraying layer, or by Alternatively, a matrix material and Mo powder may be mixed in advance, or a composite material in which Mo powder is adhered to the surface of the matrix material may be used.

The base material used is iron-based alloys such as cast iron and steel, or light metal alloys such as aluminum alloys, but since the surface of these base materials usually has irregularities of about 30 to 50 μm, thermal spraying to a sufficient thickness is used. Otherwise, the base material will be exposed and the adhesion between the sprayed layer and the base material will be weakened, so the thickness of the sprayed layer should be 50 μm.
The above is preferable.

Thermal spraying can be done using any of the following methods: gas wire, gas powder, plasma, and explosion. The sprayed material is sufficiently melted in the high-temperature frame portion 7 and rapidly cooled once it leaves the frame portion, which is advantageous for obtaining a fine sprayed layer of Mo powder.

Hereinafter, the present invention will be explained in detail with reference to Examples, where % indicates weight %.

Example 1 Hypereutectic A with a silicon content of 23.9% was added to a carbon steel 545C plate-shaped test piece (base material) with dimensions of 30 mm x 30 mm x 5 mm.
The l-8i alloy powder and the following amount of pure Mo powder were used alone or as a mixed powder of both, and 200
Abrasion test pieces (numbers 1 to 7) were prepared by thermal spraying to a thickness of μm.

In this case, the particle size of the thermal spray powder is hypereutectic Al-8i alloy,
Pure Mo powder is within the range of 100 to 400 meshes, and thermal spraying is performed after degreasing the base material and pre-treating the plastic.
It was preheated to 0°C and conducted under the following conditions.

A METCO 3M plasma spraying device was used as the thermal spraying device, and the gas was N2 (70,81/min).
+H2 (4,71/min), spraying distance 120mm
The powder feeding rate was set at 50 g/min.

Table 1 shows the surface hardness (Hv) of the test pieces thus prepared.

The state of Mo distribution in the sprayed layer of the mixed powder is shown in FIG. 1 as a micrograph of the sprayed layer for test piece number 3, and as can be seen from FIG. 1, the distribution of Mo is uniform.

Next, a) a seizure limit test and b) an abrasion test were conducted using these plate-shaped test pieces.

The mating test piece was 5Cr420 (JIS G41
Mechanical tests were conducted using a carburized and quenched cylindrical test piece (inner diameter 20 m5, outer diameter 25.6 m, length 16 mm) of No. 04) using a new friction and wear tester under the following test conditions.

Sliding speed: 24 m/sec Lubricating oil: Low viscosity oil Temperature: 60°C In the seizure limit test, the surface pressure was measured every 2 minutes. 125kg/cm2
Subsequently, the pressure was increased to a maximum of 250 kg/cm2, and the surface pressure at the time of seizure was measured.

In the abrasion test, the abrasion weight of the plate-shaped and cylindrical specimens was measured after being abraded for 1 hour under a surface pressure of 200 kg/cm2.

These results are shown in Table 1.

For comparison, the following surface treatment was applied to the base material.

Abrasion test pieces (numbers 8 to 10) were prepared and tested in the same manner as above.

The results are also listed in Table 1.

As can be seen from Table 1 above, the seizure resistance and wear resistance of the thermal sprayed layer of the hypereutectic AA-3i alloy alone (number 1) are the same as those of induction hardening (number 8) or hard chromium plating (number 9). Although it is better than that of M.

Inferior to those of thermal spraying (numbers 7 and 10).

However, by adding pure Mo powder to the hypereutectic Ag-8i alloy, the seizure resistance and wear resistance were significantly improved by 3%.
Even when added, the effect is just as good, and adding 30% gives almost the same performance as Mo spraying alone, and the abrasion weight of the plate specimen is superior to Mo spray spraying alone.

Example 2 Mo powder was used as 10% of the thermal spray material, and Mad IJ
Abrasion test pieces (numbers 11 to 20) were prepared in the same manner as in Example 1 using the following various Tux materials, and a) seizure limit test and b) abrasion test were conducted. It is shown in Table 2.

As can be seen from Table 2 above, aluminum alloys and copper alloys have relatively good seizure resistance as matrix materials, and when Mo powder is added, the seizure resistance is greatly improved. In the case of Nos. 17 to 20), the effect of adding Mo powder is very small.

Furthermore, when comparing the wear weight, there are fewer aluminum alloys than Al-15%Si alloys, and copper alloys and aluminum bronze alloys.

Although not shown in the table, this is due to the fact that the wear weight of the matrix material itself is small, indicating that even when Mo powder is added, the influence of the matrix material itself is high.

For the seizure limit tests of Examples 1 and 2, Fig. 2 shows the changes in the seizure surface pressure with respect to the amount of Mo added for test pieces Nos. 1 to 20 (excluding 8, 9, and 10). The figure also shows that the seizure resistance of the test piece obtained by adding Mo powder to the hypereutectic AA-8i alloy is improved.

Example 3 A shift fork main body part was produced by forging carbon steel material (S55C) for machine structures, and sprayed layers No. 3.9 and 10 of Example 1 were formed on the pawls corresponding to the sliding parts. I let it happen.

Attach this shift fork to an automobile drive transmission,
An actual machine evaluation was performed using low viscosity gear oil, and the wear depth (μm) of the shift fork pawl and hub sleeve was measured.

The results are shown in Table 3.

As can be seen from Table 3 above, in actual machine evaluations, the shift fork with claws formed from the sliding member of the present invention has significantly superior wear resistance compared to comparative shift forks that are commonly used in the past. There was also significantly less wear on the mating material.

In this embodiment, an example of a shift fork has been described, but the same effect can be obtained not only when applied to a shift fork but also to other sliding members, such as the inner surface of a cylinder liner, a piston ring, or a transmission friction plate. .

As is clear from the above results, the sliding member according to the present invention has excellent seizure resistance and wear resistance even when using low viscosity oil, is significantly lower in cost than thermal spraying of Mo alone, and is The manufacturing of sliding members by this method has the advantage that the degree of freedom of the base material can be increased, so that it can meet a wide range of demands for productivity, strength, wear resistance, etc. by combining it with the base material.

[Brief explanation of the drawing]

FIG. 1 is a micrograph (X400) showing the cross-sectional structure of the sliding member of the present invention, and FIG. 2 is the Mo
A graph showing changes in seizure pressure with respect to addition amount. In the figure, A... Matrix (Al-23,9%
Si), B...Mo, Number...Test piece number.

Claims (1)

[Claims] 1. A sliding member characterized in that a sprayed layer comprising 2 to 730% by weight of molybdenum and the balance aluminum alloy or copper alloy is provided on the surface of the sliding part of a base material.