JPS60248802A - Production of copper-infiltrated ferrous sintered alloy member - Google Patents

Abstract

PURPOSE:To obtain the titled member having a smooth and beautiful finish surface without pitting holes and deposit on the surface by subjecting the copper- infiltrating surface of a ferrous sintered body to a mechanical sealing treatment prior to a copper infiltration treatment of the sintered body. CONSTITUTION:A metallic powder mixture composed essentially of iron or alloy powder mixture or the powder mixture composed thereof is molded to a green compact and is then sintered or hot pressed in a vacuum or inert atmosphere, by which the sintered body is obtd. The sintered body is subjected to shot blasting, sand blasting, etc. and at least the copper-infiltrating surface is subjected to the mechanical sealing treatment. The sintered body is subjected to the copper infiltration treatment in succession thereto, by which the copper-infiltrated ferrous sintered alloy member is obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a copper-infiltrated iron-based sintered alloy member,
In particular, the present invention relates to a method for improving the finished surface of copper-infiltrated iron-based sintered alloy members used as members for valve seats, ball seats, ratchets, racks, etc. that require corrosion resistance and impact resistance.

[Prior art and its problems]

Conventionally, in order to improve the strength, density, airtightness, and corrosion resistance of iron-based sintered alloys, which are generally used as materials for parts such as valve seats, ball seats, ratchets, and racks, mixtures containing iron as the main component have been used. 1 in a sintered body obtained by sintering a green compact of metal powder and/or mixed alloy powder.
A so-called copper infiltration process is used to fill the remaining pores of 0 to 30 volume with copper or copper alloy. The temperature is higher than the melting point of copper or copper alloy, with a plate-shaped infiltration material mainly composed of copper or copper alloy placed on top of or below the sintered body.

For example, the sintered body is heated and maintained at 1,100 to 1,200° C., and a melt of copper or copper alloy is infiltrated into the pores of the sintered body, thereby filling the pores with copper or copper alloy.

The sintered body subjected to copper infiltration has strength and density of 5. Because it improves properties such as airtightness and corrosion resistance, it is used in the production of various parts as mentioned above. Conventionally, when full copper infiltration is performed, the copper or copper alloy is fused during infiltration. As a result of the reaction between the liquid and the sintered body, a part of the sintered body melts into the melt, or a compound with a high melting point is generated, causing a worm-eaten appearance mainly on the copper-infiltrated surface of the sintered body. The high melting point compound or copper or copper alloy remaining without infiltration may form and the copper infiltrated surface of the sintered body cannot be finished smoothly, resulting in a lower incidence of defective products. The cost is extremely high, and it takes a long time to finish such a surface neatly. Therefore, at present, such defects on the copper-infiltrated surface of a sintered body are a major hindrance in practical use.

[Purpose of the research and findings based on the research] From the above-mentioned viewpoints, the present inventors aimed to obtain an iron-based sintered alloy member in which the above-mentioned defects do not appear on the copper-infiltrated surface of the sintered body. As a result of research, we found that if mechanical sealing treatment such as shot blasting or sandblasting is applied to at least the copper infiltrated surface of the sintered body before copper infiltration, the above-mentioned defects may occur on the surface. C. I have found that it is possible to obtain a product that is not available.

The reason why this is possible is not clear, but
This is thought to be due to the combined effect of improving surface wettability by increasing the contact surface area, leveling out penetration by increasing the contact surface area, and preventing insect bite by making the surface uniform. This is thought to be due to some of the existing pores being sealed or some change occurring in the surface condition.

[Components of the invention]

The present invention was made based on the above knowledge, and consists of forming a mixed metal powder whose main component is iron, a crushed powder or a mixed alloy powder, or a mixed powder of both into a green compact, and then forming the powder into a compact. In a method for manufacturing a copper-infiltrated iron-based sintered alloy member by performing copper infiltration treatment on the surface of a sintered body obtained by sintering a green compact, prior to the copper infiltration treatment, sintering is performed. This method is characterized in that at least the copper infiltrated surface of the body is mechanically sealed in advance to produce a sintered alloy member with a smooth and clean surface after the copper infiltration treatment.

[Detailed description of the invention]

The present invention can be carried out using a conventional powder metallurgy method, copper infiltration treatment, and sealing treatment such as shot blasting or sandblasting, and can be carried out, for example, by the following method.

First, as raw material powder, iron, and if necessary carbon,
Metals such as copper, nickel, Fe-Ni alloy, Fe
-C! Particle size of alloys such as u alloy and Fe-Mo alloy,
Prepare each powder of 350 mesh or less and mix these powders under normal conditions to have a predetermined composition to produce a mixed metal powder whose main component is iron, a mixed alloy powder, or a mixture of both. Prepare a powder and press this mixed powder to a pressure of 3 to 6 t/cr! After compacting to form a green compact with a density ratio of about 0 to 90%, a sintered body is produced by pressing with an ordinary pressure sintering ring or real pressing in a vacuum or inert atmosphere at a temperature of 1100 to 1200°C. do.

Next, Shot Plus) or Sand Plus) is applied to this sintered body to mechanically seal at least the copper infiltrated surface, and some other pores on the surface of the sintered body are mechanically sealed. Any method such as barreling, liquid honing, or mechanical polishing can be used as long as it can be sealed and the surface condition can be changed by the treatment.

In addition, although the defects on the surface of the sintered body are likely to occur on the copper infiltrated surface, they may also occur on the surface after copper infiltration treatment, so in this case, the defects should be sealed on the copper infiltrated surface and other surfaces as well. It is necessary to carry out processing.

After the sealing treatment, a green compact of copper powder or infiltration material whose main component is copper powder, brass, bronze, or copper alloy powder containing Co, Mn, Fe, etc., prepared separately, or copper or the above-mentioned A plate-shaped infiltration material whose main component is copper alloy,
An amount sufficient to fill a predetermined amount of pores in the sintered body is placed in contact with the infiltrated surface of the sintered body, in a vacuum or in a non-oxidizing atmosphere, at a temperature in the range of 1100 to 1200°C. Copper-infiltrated iron-based sintered alloy parts are manufactured through a series of steps in which the sintered body and the infiltrant are heated and held, the infiltrated material is infiltrated into the open pores of the sintered body, and the infiltrated material is embedded. be done.

[Examples and effects based on the examples]

As a raw material powder, all commercially available particle size 10
0mesh atomized iron powder, same 150meh natural graphite, same 100mesh electrolytic copper powder, same 350m
Carbonyl nickel powder of θ8h is prepared, these raw material powders are blended into a composition corresponding to a predetermined sintered body composition, and V
After mixing for 15 minutes with a mold mixer, 4t~6t/
The green compact is molded at a pressure of ca, and then the green compact is heated in ammonia decomposition gas at a temperature of 1100 to 1150°C.
for 15 minutes to reduce the outer diameter to 30 mm as shown in the attached drawings.
It exhibits a thick ring shape with dimensions of throat x 10 inner diameter x height 10, and each contains 0.7% C-104Ou-remaining 5Fe, and (B) 0.5%V3%Ni-1.
Separate iron-based sintered alloy members having two different compositions of %Cu-remaining Fe (the above is based on weight) were manufactured.

(2) After performing sandblasting for 15 minutes using sand with a diameter of 0 and 3 mm, as shown in the drawing, the entire annular upper surface of the member subjected to the above sealing treatment ( (Fig. 1) The disc or part of it (diameter 7 brain disk) (Fig. 2)
A plate-like infiltration material made of a) 5% co-balance 9 Cu or (b) pure copper and having a thickness of 10 cm was placed, and copper infiltration treatment was performed at a temperature of 1100°C in an ammonia decomposition gas atmosphere. provided.

Furthermore, for comparison, (3) sintered '
-1 or no treatment, and (4) 3t/
The copper infiltration treatment was also performed on the sample that had been recompressed with ca in the same manner as above.

The surfaces of all the copper-infiltrated sintered alloy members obtained as described above were observed with the naked eye to evaluate the surface condition.

The above results are summarized in Table 1.

From the results shown in Table 1, all the members manufactured by the present invention have better surface conditions than the comparative copper-infiltrated iron-based sintered alloy members that were not subjected to sealing treatment. One thing is clear.

[Overall effect]

As described above, the method of the present invention produces a copper-infiltrated iron-based sintered alloy member that has a smooth and clean finished surface with no corrosion holes or adhered substances on the surface compared to conventional manufacturing methods. Therefore, when manufacturing various parts such as valve seats, ball seats, ratchets, racks, etc. that require such characteristics, it has excellent effects.

[Brief explanation of drawings]

1 and 2 are diagrams for explaining the present invention in detail, and show two methods of placing an infiltration material on a sintered alloy member of the same size. , FIG. 1 is a longitudinal sectional view when the member is placed on the entire upper surface, and FIG.
The figure (&) is a vertical sectional view when it is placed on a part of it, and the second
Figure (b) shows a plan view of the case. In the figure, 1... sintered metal member, 2... infiltration mill. Applicant Mitsubishi Metals Co., Ltd. Agent Tomi 1) Kazuo and 1 other person

Claims (1)

[Claims] Mixed metal powder or mixed alloy powder whose main component is iron,
Alternatively, a mixed powder of both of these may be molded into a green compact, and then the green compact may be sintered to obtain a copper infiltrated surface. A method for manufacturing a copper-infiltrated iron-based sintered alloy member, characterized in that, prior to the copper infiltration treatment, at least the copper-infiltrated surface of the sintered body is subjected to a mechanical sealing treatment in advance. .