JPS62120465A - Wear resistant iron-base sintered sliding material - Google Patents

Abstract

PURPOSE:To obtain an iron-base sintered sliding material having superior wear resistance and reducing the extent of wear of an opposite material at a low cost by specifying a composition consisting of C, Si, Mn, Cr, Ni, W, Mo and Fe and by uniformly crystallizing and dispersing graphite particles in a matrix. CONSTITUTION:This wear resistant iron-base sintered sliding material consists of, by weight, 2.0-4.0% C, 1.0-3.0% Si, <=0.8% Mn, <=0.3% Cr, <=2.0% Ni, <=3.0% W+Mo and the balance Fe with inevitable impurities and contains graphite particles dispersed uniformly in the matrix. Alloy powder having said composition is produced by a water atomizing process. At this time, a large amount of fine spheroidal graphite is uniformly crystallized and dispersed in the matrix by rapid cooling and the resulting alloy powder is compacted and sintered to obtain the sintered sliding material. The sintered body is used after the hardness HRC of the matrix is regulated to 55-65 by a prescribed heat treatment.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to iron-based sintered materials, and more specifically to sliding materials such as vanes, bushes, and cams, which require wear resistance of their own. This invention relates to iron-based sintered materials used in mechanical parts that need to minimize the amount of wear on mating materials while at the same time minimizing the amount of wear on mating materials.

[Conventional technology Mechanical parts, products, and electrical products have many sliding parts.

Recently, there has been an increasing demand for these parts and products to be lighter in weight, smaller in size, and higher in performance. Low alloy steel, high speed steel, etc. are generally used as sliding materials for such parts and products.

However, these materials are materials in which highly hard carbides are dispersed and precipitated in a highly hard matrix, and although they themselves have excellent wear resistance, the amount of wear on the mating material increases. Furthermore, rubbing abrasion occurs due to shedding of carbide particles and the like. This tendency becomes more noticeable as the rotational speed increases. -As an example.

Let's talk about air conditioner compressor vanes.

The vanes slide on the rotor and cylinder.

In order to improve the performance of air conditioners, the rotational speed of compressors continues to rise, and with conventional materials, both the wear resistance of vanes and the wear of rotors and cylinders increase, hindering improvements in air conditioner performance. To solve this problem, attempts have been made to use graphite vanes, but while graphite vanes are superior in terms of wear resistance and wear of mating materials, they are expensive and have low toughness. Therefore, there has been a need for a material that is low cost, has excellent wear resistance, and can minimize the amount of wear on the mating material.

Furthermore, graphite steel has been known in which some of the carbides are dispersed as graphite to improve wear resistance and workability. This is due to the lubricating effect of crystallized graphite.

This is because the coefficient of friction is small. However, the amount of graphite crystallized in this graphite steel is about 0.3 to LL%, and the remaining C forms carbides. Also, the C content is about 1
．． The limit is about 2 to 1.5%. This is because the inclusion of more C than this per ring impairs hot workability. Therefore, the level of graphite crystallization in graphite steel cannot satisfy the characteristics required of current sliding materials.

[Problem that the invention seeks to solve]

The properties required for a sliding material are wear resistance and minimal wear of the mating material.

Graphite has excellent sliding properties due to its low coefficient of friction, but its mechanical strength is low and its cost is high.

Graphite steel has high mechanical strength, but its sliding properties make it unusable for high-speed rotating parts with the current amount of graphite products available.

The present invention has been made in view of the above problems.

That is, the object of the present invention is to provide a low-cost iron-based sintered material that has properties comparable to those of graphite sliding materials, has excellent mechanical properties, and a method for producing the same.

[Means for solving problems]

The present invention is a sliding material that has improved wear resistance, minimizes wear on the mating material, is low in cost, and has high mechanical strength. S
L 1.0-3.0%, Mn 0.8% or less, Cr
O, 3% or less.

Nj, 2.0% or less, total amount of W+2Mo is 3°0% or more]
; and the balance is Fe and unavoidable impurities, and is an iron-based sintered material characterized by having graphite particles uniformly dispersed in the matrix.

[Effect]

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

C is an important element added to finely crystallize graphite in the matrix by the rapid solidification method described later. The remainder precipitates as cementite.

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

If it is 4.0% or more, the moldability and sinterability deteriorate, so that it is not practical as a mechanical structural part. Therefore, C
was set at 2.0 to 4.0%.

Si is a ferrite stabilizing element that prevents cementite crystallization and is a graphite crystallization promoting element.

If it is less than 1.0%, the crystallization effect of graphite is insufficient, and 3
．． Addition of 0% or more makes the material brittle, so 1.0~
It was set at 3.0%.

Mn acts as a deoxidizer and prevents the precipitation of FeS.
and suppress the harmfulness of S. Addition of 0.8% or more
It has no effect commensurate with the amount added and makes the material brittle. Therefore, it should be 0.8% or less.

Although Cr is a carbide-forming element, the formation of carbides is not preferable in the alloy according to the present invention, and if the content exceeds 0.3%, carbides will be formed.

Although it is preferable to have as little Cr as possible, there is an advantage that even materials containing 0.3% or less of Cr can be used as raw materials. Therefore, the Cr content was set to 0.3% or less.

Ni has the function of preventing the coarsening of crystallized graphite caused by Si, thereby increasing the tensile strength, but if it is added in excess of 2.0%, the effect is not commensurate with the amount added and it is not economical. 0% or less.

Both Mo and W are strong carbide-forming elements, but at the same time they dissolve in the matrix and strengthen the base. However, if the total amount exceeds 3.0%, it is not preferable for the sintered material of the present invention because it precipitates as a carbide rather than forming a solid solution in 71-Rix. Therefore, it should be 3.0% or less.

In the present invention, a large amount of graphite particles are uniformly and finely dispersed in the crosspiece of the sintered material having the following composition, and the friction coefficient is lowered by the lubricating effect of the graphite particles, resulting in wear and tear on the sliding material. This is to minimize the amount of

The sintered material of the present invention is subjected to a predetermined heat treatment to reduce the base hardness to I.
(RC55-65. I (If it is less than RC55, the base hardness is insufficient and the wear resistance is insufficient. Also, I-I)?
If it exceeds C65, the mechanical properties will deteriorate and the wear of the mating material will increase, so l-111G55-65 was selected.

Further, it is desirable that the graphite particles uniformly dispersed in the matrix be spherical in order to improve wear resistance and sliding properties.

According to the present invention, it is possible to produce a sintered alloy in which a large amount of graphite is uniformly and finely crystallized and dispersed, exceeding the amount of graphite in ordinary graphite steel, and is an inexpensive material with excellent wear resistance and sliding properties. can be provided.

〔Example〕

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

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

Among the alloy powders, a powder with a particle size of 150 μm or less was used, and after reduction treatment, 0.7% zinc stearate was added.
Add and mix. After press molding at a molding pressure of 6 t/d and degreasing, sintering was performed under vacuum at a temperature of 1210 to 1240°C for 1 hour. Their physical property values are also shown in Table 1.

Two types of sintered materials according to the present invention (quenched at 780-830°C, tempered at 200°C) and SKI shown in Table 1 as conventional materials.
Using sintered material equivalent to +9 and graphite steel (molten material), the 6 mating materials for which the Okoshi type wear test was conducted were FC25 rings.

Table 2 shows the results of the wear test, and the amount of wear of the sintered material of the present invention itself and the amount of wear of the mating material were compared with conventional materials.
I can see that you are doing it.

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

Table 3 Unit: μm Rotational speed 650 rpm [Effects of the invention] As explained above, according to the present invention, it is possible to improve the wear resistance of the sintered material itself and to suppress the amount of wear of the mating material as much as possible. It contributes to reducing the weight and improving the performance of products and electrical appliances, and is extremely useful in industry.

Agent Patent Attorney Hashuma Takaishi 7.2′′y″゛、°＼、
Pa.) 1-6] procedure supplement j-E + glance (['1 shot] Showa 64■1/91/6 1, Indication of the case 1985 Patent application No. 260172 2, Name of the invention Durability Wear, sliding iron-based sintered materials 3, and relationship with the amended case Patent applicant address 2-1-2 Marunouchi, Chiyoda-ku, Tokyo Name (sag) Hitachi Metals, Ltd. 4
, Claims and Detailed Description of the Invention of the specification to be amended.

5. Contents of amendment Contents of amendment 1: The claims section of the specification is amended as follows.

"1 Weight ratio Tec 2.0-4.0%, Si 1.0-
3.0%, Mn 0.8% or less, CrO, 3% or less, N
i 2.0% or less, total of W+Mo! 3.0% or less remainder F
A wear-resistant, sliding iron-based sintered material consisting of e and inevitable impurities and characterized in that graphite particles are uniformly dispersed in the matrix.

2. The wear-resistant, sliding iron-based sintered material according to claim 1, which has a base hardness of HRC55-65.

3. The wear-resistant, sliding iron-based sintered material according to claim 1 or 2, wherein the graphite particles uniformly dispersed in the matrix are spherical. ” 2. The detailed description of the invention column in the specification is amended as follows.

(1) Same book, page 4, line 17 r W + 2 M o J
rw + as shown in the attached sheet.

Claims (1)

[Claims] 1. C2.0-4.0%, Si1.0-3.0% by weight
%, Mn 0.8% or less, Cr 0.3% or less, Ni 2.0
% or less, the total amount of W + 2Mo is 3.0% or less, the balance is Fe and unavoidable impurities, and the wear-resistant sliding iron-based sintered material is characterized in that graphite particles are uniformly dispersed in the matrix. 2. The wear-resistant, sliding iron-based sintered material according to claim 1, which has a base hardness of HRC 55 to 65. 3. The wear-resistant, sliding iron-based sintered material according to claim 1 or 2, wherein the graphite particles uniformly dispersed in the matrix are spherical.