JPH05106010A - Sliding member - Google Patents

Abstract

PURPOSE:To obtain a sliding member excellent in wear resistance, causing no seizure when subjected to high load, requiring no finish working after the formation of a sprayed coating layer, and minimal in attacks on mating materials. CONSTITUTION:In the sprayed coating formed on a sliding surface, wear resistance can be maintained by using a cobalt alloy having high strength at high temp. and also seizure resistance can be secured by means of the self- lubricity of molybdenum incorporated by 2-60wt.%. Moreover, the selection of the grain size of a thermal spraying powder suffices for inhibiting the attacks on mating materials and securing required frictional force, and the conventional expensive finish working can be dispensed with. As a result, the sliding member of this invention has superior wear resistance and seizure resistance in itself and can minimize the attacks on mating materials, and further, costs can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding member such as an internal combustion engine and a transmission which are required to have wear resistance and seizure resistance, and more particularly to a synchronizer ring for a manual transmission of an automobile.

[0002]

2. Description of the Related Art Conventionally, sliding members such as an internal combustion engine and a transmission, particularly a synchronizer ring of a manual transmission of an automobile, have a predetermined frictional force at the time of synchronization and a sufficient wear resistance. Since it is required that the sliding surface has a sprayed coating of metallic molybdenum, it has been used.

Further, in Japanese Utility Model Application Laid-Open No. 57-197935, a strip-shaped resin piece obtained by dispersing and complexing a friction coefficient adjusting material made of powdery or fibrous metal or ceramics in a thermosetting resin matrix is used as a sliding surface. A synchronizer ring adhered to is proposed.

[0004]

These thermal spray coatings are usually formed by powder type flame spraying, but flame spraying has a relatively low flight speed of sprayed particles.
Since a porous film is formed, the surface roughness is rough, it cannot be used in a sprayed state, and finishing is required.

However, when the molybdenum sprayed coating is formed by flame spraying, the molybdenum is greatly oxidized and the hardness is high, so that the finishing process after forming the sprayed layer becomes expensive. Moreover, since the thermal spray coating itself is hard, the opponent's aggression is high, and the amount of wear of the opponent gear cone increases when the load is high.

On the other hand, when a thermal spray coating is formed by plasma spraying, the surface roughness can be reduced by using fine powder, but molybdenum is less oxidized and the hardness is low.
If the sliding load on the surface of the thermal spray coating is large during high load operation,
There is a drawback that the surface undergoes plastic flow and lacks durability.

In the above-mentioned proposal that the strip-shaped resin pieces in which the friction coefficient adjusting material is dispersed and composited in the thermosetting resin matrix are adhered to the sliding surface, even if the heat-resistant resin is thermosetting, a high load is applied. At this time, the temperature of the sliding surface becomes higher than the decomposition temperature of the resin due to friction, so that there is a problem in the heat resistance of the resin forming the matrix.

The present invention has been made to solve the above-mentioned problems of a sprayed coating applied to a sliding surface of a sliding member, particularly a synchronizer ring of a manual transmission of an automobile. An object of the present invention is to provide a sliding member that has a small amount of wear, is excellent in wear resistance, does not cause seizure under high load, does not require finishing work after forming a sprayed coating layer, and has a low opponent attacking property.

[0009]

In order to solve the above-mentioned problems, the inventors of the present invention have made it a material to be compounded as a sprayed coating in plasma spraying which does not require finishing after the sprayed coating is formed. We have earnestly conducted research on a material having less wear and excellent wear resistance. As a result, it was newly discovered that extremely excellent results can be obtained by using a cobalt alloy.

Further, it was found that the porosity of the sprayed layer, the size of the pores and the distribution thereof were strongly related to the aggressiveness and durability of the opponent, and the particle size of the sprayed powder for making them appropriate was found. ..

The gist of the sliding member of the present invention is that a sprayed coating composed of 2 to 60% by weight of molybdenum and the balance being a cobalt alloy is formed on the surface of the sliding portion of the base material.

Suitable cobalt alloys are so-called stellite type alloys containing up to about 6% W or Mo and up to 35% Ni, especially Japanese automobile standard JASO.
A material represented by CoCr6 or the like used as a filler material for an intake valve as shown in E101-85, for example, C: 0.5 to 4% by weight, W: 1 to 20%, C by weight ratio.
Excellent results can be obtained by using a cobalt alloy containing r: 20 to 40%, Ni: 0.5 to 30%, and the balance being Co and an impurity element.

In the thermal spraying, molybdenum powder and cobalt alloy powder, which are thermal spraying materials, may be separately supplied to a thermal spraying apparatus and simultaneously sprayed to form a desired thermal spray coating. It may be supplied to a thermal spraying device to form a thermal spray coating.

As the base material, iron-based alloys such as cast iron and steel or non-ferrous alloys such as aluminum alloys and copper alloys are used. Since the surface of these base materials usually has irregularities of 30 to 50 μm, thermal spraying is performed. The thickness of the coating is preferably 50 μm or more.

The thermal spraying method is not particularly limited, but it is preferable to use the plasma thermal spraying method in order to prevent the oxidation of molybdenum particles and suppress the opponent attack of the thermal spray coating.

In order to make the porosity of the thermal spray coating, the size of the pores and the distribution state thereof appropriate, and further to enhance the effect of the present invention, the thermal spray coating is formed using a thermal spray material having a powder particle size of 200 mesh or less. Preferably.

Further, in order to secure a required friction coefficient, the surface roughness of the sprayed coating is 20 μm in terms of ten-point average roughness.
Rz to 70 μmRz is preferable.

[0018]

When a cobalt alloy is used alone, seizure occurs at high loads, but since the sprayed coating contains 2 to 60% by weight of molybdenum, which has self-lubricating properties, seizure at high loads is prevented. Cobalt alloy is a material having excellent wear resistance at high temperature operation, but it imparts wear resistance to the sprayed layer and suppresses opponent attack.

In the present invention, if the molybdenum powder and the cobalt alloy powder, which are thermal spraying materials, are made to be 200 mesh or less, the opponent attacking property can be further suppressed.

Further, in the present invention, by setting the surface roughness of the thermal sprayed layer to be 10-point average roughness of 20 μmRz to 70 μmRz, a proper friction coefficient is secured, and the opponent attacking property is suppressed and the durable life is improved. To do.

In the present invention, the content of molybdenum in the thermal spray coating is set to 2 to 60% by weight. When the content is less than 2%, the thermal spray coating cannot be provided with sufficient self-lubricating property and seizure occurs under high load. This is because if the content exceeds 60%, the hardness of the thermal spray coating decreases, plastic flow occurs on the surface at high load, and wear resistance deteriorates.

Generally, the thermal spray coating has pores, and on the sliding friction surface of the synchronizer ring, the lubricating oil present on the surface of the mating gear cone at the time of friction is allowed to escape to the pores, so that the spray coating surface and the gear cone are provided. It generates metal contact and secures the required friction coefficient.

Therefore, when the pores are large, the displacement of the lubricating oil is promoted, the metal contact is strengthened, the aggressiveness against the opponent is strengthened, and the durability life is shortened. In order to make the porosity, the size of the pores and the distribution state thereof appropriate, the particle size of the thermal spray powder has a great influence, and in consideration of this, the powder particle size is preferably 200 mesh (74 μm) or less.

If the surface roughness of the surface of the sprayed coating is less than 20 μmRz, the desired coefficient of friction cannot be secured as described above. On the other hand, when it exceeds 70 μmRz, the attacking property against the opponent becomes large and the durability life becomes short.

[0025]

EXAMPLES Examples of the present invention will be described together with conventional examples and comparative examples to clarify the effects of the present invention. As a thermal spraying powder, C; 1.0%, W; 4.0%, Cr; 28 by weight ratio.
%, Ni: 3.0%, Fe: 3.0%, and the balance being Co and impurity elements (cobalt alloy powder (Co
Cr6, commonly known as stellite No. 6) and molybdenum powder, as a conventional example, a comparative example and an invention example, using the compounding ratio and the thermal spraying method shown in Table 1, a general structural rolled steel sheet (SS41).
A thermal spray coating having a thickness of 0.2 mm was formed on the above. The average particle size of the sprayed powder was 200 mesh. Measuring the porosity and coating cross-section hardness of the resulting sprayed coating,
The results are also shown in Table 1.

[0026]

[Table 1]

Next, the same thermal spray coating as shown in Table 1 was applied to the friction surface of the synchronizer ring and a wear test was conducted. The synchronizer ring is a base material made of high-strength brass and sprayed on the friction surface. Also, the base material is SC as the mating material.
A cone, which is a carburized and quenched material of M415, was used, and the friction surface of the cone was ground and finished.

The test condition is a pressing load of 1960 N (200
kgf), sliding speed 4 m / sec, pressing frequency 5000 times,
It was performed by dipping in oil. The oil used was 75W-90 gear oil. FIG. 1 shows the wear amounts of the sprayed surface of the synchronizer ring and the mating cone.

From the results of Table 1 and FIG. 1, the conventional example (A)
Since the sprayed powder was only molybdenum and was flame sprayed, the porosity was as large as 20%, the repulsion of the lubricating oil on the mating cone was large during sliding, metal contact occurred, and the sprayed coating Since the hardness was as high as Hv700, the amount of wear of the sprayed surface itself was small, but the amount of wear of the mating material cone was large.

In the conventional example (B), the sprayed powder was molybdenum only, but plasma spraying was performed, so that the sprayed coating had Hv2.
It was as soft as 80, and when pressed against the mating material, the surface underwent plastic flow. Therefore, wear of the mating material was small, but wear of the thermal spray coating itself was large.

In the conventional example (C), only the cobalt alloy was plasma-sprayed, but the sprayed surface was slightly seized and the amount of wear was large. Comparative Example (D) contains a larger amount of molybdenum than the composition range of the present invention, but due to the large amount of molybdenum, as in the case of Conventional Example (B), the surface of the sprayed surface was plastically flowed, resulting in a large amount of wear. ..

On the other hand, invention examples (E) and (F)
Has a porosity of 4% and a hardness of Hv315 to 335, which is within an appropriate range, so that seizure does not occur, self-abrasion is equal to or less than the flame spraying of molybdenum in (A), and abrasion of the mating cone is (B). It was found to be equal to or less than that of the plasma spraying of molybdenum), and the effect of the present invention was confirmed.

[0033]

As described above, the sliding member of the present invention is characterized in that a sprayed coating composed of 2 to 60% by weight of molybdenum and the balance of cobalt alloy is formed on the surface of the sliding portion of the base material. The thermal spray coating of the present invention maintains wear resistance with a cobalt alloy having high strength at high temperature, and contains 2 to 60% by weight of molybdenum, and seizure resistance is secured by self-lubrication of molybdenum. Further, in the present invention, in order to suppress the opponent attacking property and to secure the necessary frictional force, it suffices to select the particle size of the sprayed powder and does not require expensive finishing as in the prior art. Therefore, the sliding member of the present invention is excellent in wear resistance and seizure resistance by itself, and can minimize the opponent attacking property, and further, the cost is low, and besides the synchronizer ring, the claw of the shift fork is provided. It is also extremely useful for parts, pistons, cylinder liners, piston rings and transmission friction plates.

[Brief description of drawings]

FIG. 1 is a diagram showing a wear amount in a wear test of a sliding member of a conventional example, a comparative example, and an invention example with a counterpart member.

Claims (4)

[Claims] 1. A weight ratio of 2 to 60% on the surface of the sliding portion of the base material.
2. A sliding member, characterized in that a sprayed coating of molybdenum and the balance of cobalt alloy is formed. 2. The cobalt alloy comprises C; 0.
5-4%, W; 1-20%, Cr; 20-40%, N
i: 0.5 to 30%, with the balance being Co and an impurity element, The sliding member according to claim 1. 3. The sliding member according to claim 1, wherein the thermal spray coating is formed using a thermal spray material having a powder particle size of 200 mesh or less. 4. The sliding member according to claim 1, wherein the surface roughness of the thermal spray coating is a ten-point average roughness of 20 μmRz to 70 μmRz.