JPS5943801A - Manufacture of sintered aluminum or aluminum alloy material - Google Patents

Abstract

PURPOSE:To obtain stably a high strengh sintered material by sintering each green compact of Al powder under a specified pressure so as to extend the sintering temp. range and to make various kinds of atmospheric gases applicable. CONSTITUTION:Green compacts 3 formed by press-molding powder of Al or an Al alloy as a starting material are held between surface plates 1, 1 while interposing partition plates 2 made of iron, ceramics or the like, and the compacts 3 are sintered under 0.1-10kg/cm<2> oil pressure or other pressure. By this method, the sintering temp. range can be extended, and a reducing gas typified by decomposed gaseous NH3 or air as well as a conventional high purity inert gas is applicable as the atmospheric gas.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for stably and reliably manufacturing highly durable aluminum and aluminum alloy sintered materials.

In recent years, aluminum or aluminum alloy sintered materials have been widely used as parts for automobiles and home appliances because they are lightweight, have excellent corrosion resistance, and can produce products with high precision in dimension. It is becoming more and more common.

Conventionally, pure AI, At-Cu alloy, At-Mg alloy.

When manufacturing aluminum-based sintered materials such as AL-8t alloy and At-Cu-C alloy, these raw material powders are extremely susceptible to oxidation, and sinterability is significantly inhibited by oxidation. After compacting, sintering is performed in a high purity inert gas such as liquefied N2 gas.

However, sintering under such conditions has the problem that the temperature range that can be sintered is extremely narrow, resulting in large variations in the strength and other properties of the manufactured sintered bodies. It has not been possible to solve the problem of difficulty in mass production and high costs because it is sensitive to changes in the amount of gas during bonding, resulting in oxidation or a decrease in strength due to this.

From the above-mentioned viewpoint, the present inventors have achieved stable and high-strength aluminum and aluminum alloy sintering without being particularly affected by the effects of the sintering atmosphere, such as the atmospheric gas or the sintering temperature. We need to find a way to produce all the phased products ('
As a result of conducting 47F research, it was found that when sintering aluminum and aluminum alloy green compacts, the sintering temperature range can be expanded by pressurizing 4 times at a specific pressure. Haku: In addition to gas, NH
3 Reducing gases represented by decomposition gases, and even the atmosphere, can be applied, and high strength I
We have come to the knowledge that it takes only a few hours to stably produce the sintered phase (2).

This invention was made based on the above knowledge, p1
In the production of aluminum or aluminum alloy 931 material, the raw material powder is subjected to Sores formation 11*1 and then sintered under a pressure of 0.1 to 10 kf/cn to form aluminum or aluminum with the highest strength. This method is characterized by producing a sintered aluminum alloy material.

Note that the raw material powder used in this invention can be the one used in the production of ordinary aluminum-based sintered materials, and any sintering atmosphere gas can be used as long as it is not strongly oxidizing. can do.

In addition, in the method of this invention, the reason why the pressurizing force during sintering is set at 0.1 to 10 kg/cn as described above is that if the pressurizing force is less than 0.1 kp/cJ, In gases (NHa gas, etc.), the inside of the green compact is oxidized and sintering does not proceed, resulting in a decrease in the strength of the sintered product, and even in Nz gas, sintering at low temperatures may be impossible. On the other hand, the pressing force is I Okg/Cr! If it exceeds 0, the dimensional precision U of the sintered product cannot be obtained sufficiently, and the above improvement effect cannot be expected due to the improvement in strength of the sintered product, the density of manual hammering, and the reduction of the sintering temperature.

And, in the method of this invention, baked L! At time i, a predetermined pressing force is applied to the powder compact in one J=stage and L5 at 7, for example, a method as shown in FIGS. 1, 2, and 3 can be adopted.

In the method shown in FIG. 1, an aluminum or aluminum alloy green compact 3 is sandwiched between surface plates 1.1 via a partition plate 2 such as an iron plate or a ceramic plate, and then
This applies a pressing force of ~10 kg/cn, and the one shown in FIG. 2 is similar to that shown in FIG. 0.0 by a lever rod 4 which is swingably supported at one end and a load is applied to the other end.
This shows a method of applying a pressurizing force adjusted to 1 to 10 kv/m.

In addition, in FIG. 2, 5 indicates a fulcrum. And the third
The one shown in the figure is related to a pressurizing method that enables continuous sintering, in which a powder compact 3 is placed on a moving belt 6 via a surface plate 1, and a weight is placed on top of it. I! 7 is applied to apply a pressing force, and can be applied to a device that applies a pressing force of about 0.1 to 0.5 kr/crI.

Next, the present invention will be explained using examples and comparing with comparative examples.

Example First, the composition was as shown in Table 1, and 5.5
Compressed with tons/LyI, dimensions are 7X51X91 (
m) Green compacts (test materials) A to C were prepared.

Next, this green compact was sintered under the sintering conditions shown in Table 2 to obtain a plate-shaped sintered material. In this case, it goes without saying that the higher the pressure, the more effectively the sintering temperature can be lowered, and the sintering time can also be shortened.

The results of measuring the tensile strength of the sintered material thus obtained are also shown in Table 2.

The results shown in Table 2 also show that the aluminum and aluminum alloy sintered materials manufactured by methods 1 to 18 of the present invention have high strength without being oxidized except for the surface layer. Sintered 4= produced by comparative methods 19 to 22 and 24 where the applied force is lower than the range of the method of the invention
No. 4 had low strength due to oxidation, etc., and had large cracks. Furthermore, the sintered material sized by Comparative Method 23, in which the pressing force was greater than the range of the method of the present invention, had poor dimensional accuracy, although the strength was almost the same as that of the method of the present invention.

As described above, according to the present invention, high-strength aluminum and aluminum alloy sintered materials can be stably and reliably mass-produced without being affected by the sintering car surroundings and within a wide sinterable temperature range. It can be used as brake shoes and sliding materials in place of general iron-based sintered materials.

Alternatively, industrially useful effects can be brought about, such as being able to take a step further in terms of the strip fl applied to clutch materials and the like.

[Brief explanation of drawings]

FIG. 1, FIG. 2, and FIG. 3 are conceptual diagrams showing a method for pressurizing a green compact after sintering, and each figure shows a different embodiment. On one side, 1...surface plate, 2...partition plate, 3...
Green compact, 4... lever, 5... fulcrum,
6... Belt, 7... Weight. Applicant Mitsubishi Metals Corporation

Claims (1)

[Claims] In the production of aluminum or aluminum alloy sintered materials, the raw material powder is press-molded and then press-molded (1,1~
1. A method for producing a high-strength aluminum or aluminum alloy sintered material, which comprises sintering under Okf/crl.