JPH0645861B2 - Sliding member - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sliding member that exhibits excellent seizure resistance and the like even under conditions where a lubricating oil film is difficult to form.

<Prior Art> In recent years, various sliding members such as shift fork claw portion, synchronizer ring inner surface, cylinder liner inner surface, piston ring, and mesh friction plate have been subjected to higher surface pressure due to the demand for higher output and lower heat cost of automobiles. Has come to be used in. In such a case, seizure and abnormal wear are likely to occur in the sliding portion, and therefore, it is required to improve the performance of the sliding member, especially seizure resistance and wear resistance, more than ever. Regarding sliding members, for example, shift forks, induction hardening, hard chrome plating, and aluminum bronze thermal spraying were conventionally performed on the claws, but they are no longer applicable under the recent severe sliding conditions. It's starting. Therefore, a method has been proposed and adopted in which a material having excellent sliding characteristics is sprayed on the surface of the sliding portion by plasma spraying or the like to improve the sliding characteristics.

The main prior art is to provide a thermal sprayed layer consisting of 5-85 wt% high carbon ferrochrome and the balance aluminum bronze alloy (see Japanese Patent Laid-Open No. 56-99525), particle size 5 μm.
The area ratio of the following primary silicon is 2 to 20% in the matrix.
One provided with a dispersed hypereutectic Al-Si alloy sprayed layer (see JP-A-56-166368), and a sprayed layer consisting of 2 to 30% by weight of molybdenum and the balance aluminum alloy or copper alloy. The one provided (see Japanese Patent Application Laid-Open No. 57-19370) is known.

<Problems to be Solved by the Invention> However, recently, in order to reduce friction loss, the direction of reducing the friction area, sliding at high speed and under high surface pressure, and lowering the viscosity of lubricating oil has been strongly pursued. In some cases, there is a problem that the conventional product cannot be used.

This is because the oil film is less likely to be formed on each sliding part and it is more likely to cause seizure or abnormal wear.Therefore, the sliding member itself lacks self-lubricity. It is due.

The present invention has been made for the purpose of solving the above problems, and the problem to be solved is to provide excellent seizure resistance and wear resistance even when used under conditions where a lubricating oil film is difficult to form. It is to provide a sliding member that exhibits the property.

<Means for Solving the Problems> A sliding member of the present invention capable of solving the above problems is a thermal sprayed layer made of 2 to 35% by weight of silver and the balance aluminum alloy or copper alloy on the sliding part surface of a base material. Is provided.

The aluminum alloy used in the present invention includes Al-Si
Although there are alloys, Al-Pb alloys, etc., a hypereutectic Al-Si alloy is preferable. As the copper alloy, an aluminum bronze alloy, a phosphor bronze alloy, or the like is preferable.

It is necessary to set the amount of silver to 2 to 35% by weight is 2% by weight
If it is less, the seizure resistance is not improved, while if it exceeds 35% by weight, the strength of the thermal sprayed layer itself is reduced and wear is increased, and as a result, the seizure resistance is also reduced.

As the base material, an iron-based alloy such as copper or cast iron, or a light metal alloy such as an aluminum alloy or a magnesium alloy can be used.

In the thermal spraying, each of the aluminum alloy or copper alloy powder as a matrix material and the silver powder may be separately supplied to the thermal spraying apparatus and simultaneously sprayed to form a target thermal sprayed layer, or the thermal spraying may be performed. It may be performed by using a mixture of the matrix material powder and the silver powder in advance before the supply to the apparatus, or a composite material in which the silver powder is attached to the surface of the matrix material powder. It is desirable that the particle size of each powder be smaller than 350 mesh (44μ). This is because if it is coarser than 44μ, the sprayed layer has many pores and wear resistance decreases.

As for the thickness of the sprayed layer, since the roughness of the sprayed layer is about 30 to 50 μ, a sprayed layer of 50 μ or more is suitable, and about 200 μ is preferable.

As the thermal spraying method, plasma type, gas melting type, gas powder type,
Any method such as a linear explosion method may be used.

<Operation> The present sliding member configured as described above shows the same or higher level of wear resistance and a further improved level of seizure resistance as compared with a sliding member having a single thermal spray layer of matrix material. Also, the wear of the mating material (cast iron FC25, carbon copper S45C, etc.) is further reduced, which is thought to be due to the following action.

The disadvantage of the matrix material, which is easy to seize when the formation of a lubricating oil film is small, is compensated by silver, which excels in self-lubrication, and the abrasion weakness of silver is compensated by the matrix material, which has excellent abrasion resistance. Even under conditions where an oil film is unlikely to be formed, the self-lubricating property of silver prevents seizure, which also has a positive effect on preventing abnormal wear of itself and the mating material.

<Example> Hereinafter, the sliding member of the present invention will be specifically described based on Examples. In the examples,% represents% by weight (wt%) unless otherwise specified.

Example 1 Carbon steel having an outer diameter of 25.6 mm, an inner diameter of 20.0 mm and a length of 16 mm (JIS S45
Each of the end faces of the cylindrical piece made of C) was subjected to the treatment shown in Table 1 below, and then the treated surface was ground to produce various rotary friction test pieces (Examples F to I, Comparative examples A to E, J, K) was produced. The thickness of the plated layer and the sprayed layer was 0.02 to 0.3 mm, and the treatment operation itself was performed according to a conventional method.

A seizure test for measuring the seizure limit load was carried out under the following conditions by rotating each of the test pieces A to K and a separately prepared mating material in rotary contact while increasing the load.

Counterpart material… Induction hardening of carbon steel JIS S45C (Shape dimensions are the same as the test piece, Hv600) Lubricating oil… Motor oil SAE30 (manufactured by KATSUSURU) Load… 25Kg to 500Kg Revolution… 7000rpm (Lubrication condition of contact surface) Shows a rotational speed at which the centrifugal force significantly deteriorates.) The result of the seizure test is shown in FIG.

Then, a wear test was carried out in which a frictional load of 50 kg was applied for 1 hour to measure the amount of wear of both the test piece itself and the mating material. The results of this wear test are shown in FIG.

The following can be understood from the results of the above-mentioned seizure test and abrasion test.

(A) The thermal sprayed products (C to J) using the hypereutectic Al-Si alloy are more excellent in seizure resistance and wear resistance than the other products (A, B, K).

(B) Above all, rather than hypereutectic Al-Si alloy single thermal spraying (C),
Those sprayed by adding Mo or Ag (DJ) are superior.

(C) In the comparison between the addition of Mo and the addition of Ag, the addition of Ag shows a great improvement in wear resistance, particularly seizure resistance.

(D) However, it is affected by the amount of Ag added, and the addition of 20% by weight of Ag maximizes the seizure resistance, and the addition of 10% by weight minimizes the wear resistance of itself. It can be said that the preferable range is 2 to 35% by weight.

Example 2 Various thermal spray materials each containing 10% by weight of Ag powder were used,
Rotational friction test pieces (Examples M to Q, Comparative Example) as in Example 1.
L, R ~ T) were manufactured. The matrix materials are shown in Table 2.

The test pieces L to T were subjected to a seizure test and an abrasion test in the same manner as in Example 1, and the results shown in Table 3 were obtained.

The results shown in Table 3 show the following.

(i) For seizure resistance, aluminum alloy (MO)
It is preferable to use a copper alloy (P, Q) as a matrix material.

(ii) The same applies to wear resistance, but especially Al-15% Si
Alloy (N) and aluminum bronze alloy (P) are good.

(iii) The effect of adding Ag (the effect of improving seizure resistance) is remarkable in aluminum alloys and copper alloys, but 0.8% carbon steel, pure Cr,
It is a little in pure Ni. As for wear resistance, Ag
It seems that the effect of the matrix material itself is higher than that of the addition.

Example 3 A carbon steel material for machine structure (JIS S45C) was forged to manufacture a shift fork main body part, and the A, C, D and G sprayed layers of Example 1 were formed on the claws corresponding to the sliding parts. It was formed and a shift fork was made as a prototype.

I attached this shift fork to an automobile drive transmission,
Using low-viscosity gear oil, the following conditions: Shift load: 100 kg Sleeve speed: 5000 rpm Endurance cycle: 50000 ∞ The actual machine evaluation was performed, and the wear depth of shift fork claws and hub sleeves (JIS SCr420H, carburized and hardened) Was measured. The results are shown in Table 4.

As can be seen from Table 4, the shift fork having the claws formed by the sliding member of the present invention is significantly superior to the conventional general-purpose shift fork in abrasion resistance and significantly reduces the wear of the mating material. ing.

Although the example of the shift fork has been described in the example related to the evaluation of the actual machine, it is obvious that the same effect can be obtained when applied to other sliding members such as the inner surface of the cylinder liner and the inner surface of the synchronizer ring. is there.

<Effects of the Invention> As can be seen from the above description, the sliding member of the present invention has excellent seizure resistance and wear resistance (including the mating material) even when used under conditions where a lubricating oil film is difficult to form. Indicates.

Further, since the sliding member of the present invention is manufactured by the thermal spraying method, the degree of freedom of the base material is large, and various base materials such as aluminum alloy, steel and cast iron can be used. Therefore, by appropriately selecting the base material, It has the advantage that it can meet a wide range of requirements such as productivity, strength, and wear resistance.

[Brief description of drawings]

1 and 2 are graphs showing seizure test results and wear test results of various sliding members.

Claims (1)

[Claims] 1. A sliding member, characterized in that a thermal sprayed layer consisting of 2 to 35% by weight of silver and the balance of aluminum alloy or copper alloy is provided on the surface of the sliding portion of the base material.