JPH0772330B2 - Abrasion resistant, sliding iron-based sintered material - Google Patents

Description

TECHNICAL FIELD The present invention relates to an iron-based sintered material, and more particularly to a sliding material such as a vane, a bush, and a cam, which requires its own wear resistance. At the same time, the present invention relates to an iron-based sintered material used for a machine part that requires minimizing the amount of wear of the mating material.

[Conventional technology]

Mechanical parts / products and electrical products have many sliding parts.
Recently, demands for weight reduction, miniaturization, and high performance of these parts and products are increasing. Low-alloy steel, high-speed steel, and the like are commonly used as sliding materials for such parts and products. However, these materials
It is a material in which high-hardness carbide is dispersed and precipitated in a high-hardness matrix, which itself has excellent wear resistance,
The amount of wear of the mating material increases. Furthermore, rubbing wear occurs due to falling of the carbide particles. This tendency becomes remarkable as the rotation speed increases. As an example, the vane of an air conditioner compressor will be described.

The vane slides on the rotor and cylinder. In order to improve the performance of air conditioners, the number of revolutions of compressors keeps increasing, and with conventional materials, both vane wear and rotor and cylinder wear increase, impeding the improvement of air conditioner performance. In order to solve this problem, it has been attempted to use graphite vanes, but the graphite vanes are excellent in terms of wear resistance and the amount of wear of the mating material, but they are high in cost and low in toughness. Therefore, there has been a demand for a material that is low in cost, has excellent wear resistance, and can minimize the amount of wear of the mating material.

Further, conventionally, graphite steel is known in which a part of carbon is dispersed as graphite to improve wear resistance and workability. This is because the coefficient of friction is small due to the lubricating effect of crystallized graphite. However, the crystallized amount of graphite in this graphite steel is
It is about 0.3 to 1.1%, and the remaining C forms carbide. The C content is limited to about 1.2 to 1.5%. The reason is that the inclusion of C in excess of this deteriorates the hot workability. Therefore, at the graphite crystallization amount level of graphite steel, the properties required for the current sliding materials cannot be satisfied.

[Problems to be solved by the invention]

The characteristics required of the sliding material are wear resistance and minimizing the wear of the mating material.

Graphite has excellent sliding characteristics due to its low coefficient of friction,
Low mechanical strength and high cost.

Graphite steel has high mechanical strength, but its sliding properties cannot be used as high-speed rotating parts with the current graphite crystallization amount.

The present invention has been made in view of the above problems, that is, an object thereof is to provide a low-cost iron-based sintered material having frictional properties similar to those of a graphite sliding material and further excellent mechanical properties. To do.

[Means for solving problems]

The present invention is a sliding material having improved wear resistance and reduced wear of the mating material as much as possible, low cost and high mechanical strength, that is, C2.0 to 4.0% by weight and Si1.0 to 3.0. %, M
n 0.8% or less, Cr 0.3% or less, Ni 2.0% or less, the total amount of W + Mo is 3.0% or less, and the balance Fe and unavoidable impurities,
The iron-based sintered material is characterized in that graphite particles are uniformly dispersed in the matrix.

[Action]

 The reasons for limiting the components of the sintered material of the present invention will be described below.

C is an important element added for finely crystallizing graphite in the matrix by the rapid solidification method described later. The rest precipitates as cementite.

When C is less than 2.0%, the amount of graphite is at the level of the current graphite steel, and there is no improvement in sliding characteristics and wear resistance.

If it exceeds 4.0%, the formability and sinterability will deteriorate and it will not be practically used as a mechanical structural part. Therefore,
C was set to 2.0 to 4.0%.

Si is a ferrite stabilizing element that prevents crystallization of cementite and is an element that promotes crystallization of graphite.

If less than 1.0%, the crystallization effect of graphite is insufficient and 3.0%
If it exceeds 1.0%, the material becomes brittle, so the content was made 1.0 to 3.0%.

Mn is a deoxidizing agent and prevents precipitation of FeS to MnS, S
Control the harmful effects of. Addition in excess of 0.8% has no effect of matching the addition amount and embrittles the material. Therefore 0.
8% or less.

Although Cr is a carbide-forming element, in the alloy according to the present invention, carbide formation is not preferable, and carbide is formed at a content exceeding 0.3%.

It is preferable that Cr is as small as possible, but there is an advantage that even a material containing 0.3% or less of Cr can be used as a raw material. Therefore, Cr is set to 0.3% or less.

Ni has a function of preventing coarsening of crystallized graphite due to Si,
As a result, the tensile strength is increased, but if it exceeds 2.0%, there is no effect corresponding to the added amount and it is not economical, so it is made 2.0% or less.

Both Mo and W are strong carbide-forming elements, but at the same time they form a solid solution in the matrix to strengthen the matrix. However, if the total amount exceeds 3.0%, it precipitates as a carbide rather than as a solid solution in the matrix, which is not preferable for the sintered material of the present invention. Therefore, it should be 3.0% or less.

In the present invention, graphite particles are uniformly dispersed in a large amount in the matrix of the sintered material having the above composition, the coefficient of friction is lowered by the lubricating effect of the graphite particles, and the wear of the sliding mating material is minimized. It is a thing.

The sintered material of the present invention is subjected to a predetermined heat treatment to have a base hardness of H.
RC-55 to 65. If it is less than HRC55, the matrix hardness is insufficient and the wear resistance is not sufficient. Also, if HRC65 is exceeded, mechanical properties will deteriorate and wear of the mating material will increase.
It was set to 55-65.

Further, it is desirable that the graphite particles uniformly dispersed in the matrix have a spherical shape in order to improve wear resistance and sliding characteristics.

According to the present invention, it is possible to manufacture a sintered alloy in which a large amount of crystallization is dispersed uniformly and finely in excess of the amount of graphite of ordinary graphite steel, and an inexpensive material excellent in wear resistance and sliding characteristics. Can be provided.

〔Example〕

 Hereinafter, the present invention will be described in detail based on examples.

Example 1 An alloy powder having the composition shown in Table 1 was produced by a water atomizing method.

Of the alloy powder, a powder having a particle size of 150 μm or less is used,
After the reduction treatment, 0.7% of zinc stearate was added and mixed. Press-molded at a molding pressure of 6 t / cm ² and degreased, then under vacuum 1210-12
Sintering was carried out at a temperature of 40 ° C. for 1 hour. Those plant values after heat treatment under the following conditions are also shown in Table 1.

Two kinds of sintered materials according to the present invention (quenching at 780 to 830 ° C, 200
The mating material subjected to the Ogoshi-type wear test was FC25 ring, using tempered material (° C tempering) and conventional materials such as SKH9 sintered material shown in Table 1 and graphite steel (molten material).

The results of the abrasion test are shown in Table 2, and it can be seen that both the abrasion amount of the sintered material of the present invention and the abrasion amount of the mating material are improved as compared with the conventional material.

Example 2 The same material used in Example 1 was processed as a compressor vane, and the vane, cylinder, and rotor wear amounts after 100 hours of continuous operation were measured, and the results are shown in Table 3.

[Effects of the Invention] As described above, according to the present invention, it is possible to improve the wear resistance of the sintered material itself and suppress the wear amount of the mating material as much as possible, and reduce the weight and mechanical weight of mechanical parts / products and electrical products. It contributes to performance improvement and is very useful in industry.

Claims (2)

[Claims] 1. A weight ratio of C2.0-4.0%, Si1.0-3.0%, Mn
0.8% or less, Cr 0.3% or less, Ni 2.0% or less, W + Mo total amount
3.0% or less The balance consists of Fe and unavoidable impurities, graphite particles are uniformly dispersed in the matrix, and the matrix hardness is HR.
A wear-resistant, sliding iron-based sintered material characterized by C55 to 65. 2. A wear-resistant, sliding iron-based combustion material according to claim 1, wherein the graphite particles uniformly dispersed in the matrix are spherical.