JPH09202930A - Metal-ceramics composite material and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce the composite material having sufficient strength at ordinary temp. and minimal in the reduction of strength even at high temp. by previously forming aluminum nitride layer on the surface of alumina fiber at the time of making aluminum penetrate into a preform constituted of alumina fibers. SOLUTION: The metal-ceramics composite material is produced by making aluminum or aluminum alloy, as base material, penetrate into a preform constituted of alumina fibers or grains as reinforcement. At this time, the alumina fibers or grains are mixed with carbon powder, and the resultant mixture is heated in a nitrogen atmosphere at >=1,700 deg.C, by which aluminum nitride layer is formed on the surface of the alumina fibers or grains previously. By this method, wettability between the alumina fibers or grains and the aluminum or aluminum alloy can be improved, and the metal-ceramics composite material, having strength at ordinary temp. and high temp. strength higher than those of the conventional one, can be obtained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a metal-ceramic composite material, and more particularly to a metal-ceramic composite material in which the metal is aluminum or its alloy and the ceramic is alumina.

[0002]

2. Description of the Related Art Light metals such as aluminum and their alloys are widely applied to metallic materials used in the fields of transportation and aviation because of their favorable characteristics of light weight. However, as the applications of these metals have become more sophisticated, it has become difficult to meet the requirements in terms of performance such as specific strength and specific elasticity of the metals.

Under these circumstances, in recent years, MMC (Me) in which these metals are reinforced with inorganic fibers or particles is used.
A metal-ceramic composite material, which is abbreviated as "tal Matrix Composite", has been attracting attention as a material satisfying the above requirements. This is a composite material in which a preform is formed by previously molding inorganic fibers or particles that are a reinforcing material, and a metal that is a base material (matrix) is infiltrated between fibers or particles of the preform. As the reinforcing material used, ceramics such as alumina, silicon carbide, silica, and carbon are used, and among them, alumina is considered to be the most promising in terms of cost.

[0004]

However, a composite material reinforced by using this alumina as a reinforcing material has a problem that it is difficult to obtain sufficient strength for the following reasons, and the strength is largely decreased at high temperature. was there. (1) Since the molten matrix aluminum or its alloy has poor wettability with alumina which is a reinforcing material,
Even when it is permeated at a high pressure, it is difficult for the matrix to completely spread over the entire preform, and voids are formed between fibers or particles, resulting in incomplete strength enhancement. (2) When the matrix comes into contact with the preform, the alumina reacts with the additive element in the matrix at the interface,
For example, if the additive element is magnesium, spinel is generated at the interface to form an embrittlement layer, resulting in incomplete strength enhancement. (3) Since the finished composite material is exposed to a high temperature during its use, a similar embrittlement layer is further formed by the reaction and diffusion of the matrix and the preform, which leads to a large decrease in strength at a high temperature.

The present invention has been made in view of the problems of the conventional metal-ceramic composite material using aluminum or its alloy as the metal and alumina as the ceramic and the method for producing the same. ,
An object of the present invention is to provide a metal-ceramic composite material which has a sufficient strength at room temperature and has a small decrease in strength even at a high temperature, and a method for producing the same.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above-mentioned object, and as a result, if alumina fibers or particles having an aluminum nitride (AlN) layer formed on the surface were used as a reinforcing material, at room temperature, Demonstrate sufficient strength,
The present invention has been completed based on the finding that a metal-ceramic composite material can be obtained which has a small decrease in strength even when used at high temperatures.

That is, the present invention relates to (1) a metal-ceramic composite material obtained by impregnating aluminum or its alloy as a base material into a preform composed of alumina fibers or particles as a reinforcing material. A metal-ceramic composite material (claim 1) characterized in that the particles are alumina fibers or particles having an aluminum nitride layer on the surface thereof, and (2) reinforced alumina fibers or particles having an aluminum nitride layer on the surface. Forming a preform as a material, in the method for producing a metal-ceramic composite material in which aluminum or an alloy thereof is infiltrated into the preform, the method of forming an aluminum nitride layer on the surface of alumina fibers or particles, alumina fibers or particles Mix with carbon powder and place the mixture in a nitrogen atmosphere. A method of heating at 1700 ° C. or higher, a method of infiltrating aluminum or its alloys, metal characterized in that it is a high-pressure casting - and gist a method for manufacturing a ceramic composite material (claim 2).
This will be described in more detail below.

Alumina has poor wettability with metals, but Al
Focusing on the fact that N has good wettability with metal, by making only the surface of alumina AlN, alumina has good wettability with metal.
Since it is a composite material produced by using 1N-ized alumina, the above-mentioned problem (1) using alumina in which an AlN layer is not formed on the surface is improved.

Further, since the surface of the alumina is covered with the AlN layer, the reaction between the alumina and the additive element in the aluminum is suppressed, and the above-mentioned problem (2) is improved. Furthermore, the reaction under high temperature is also suppressed, and the problem (3) is improved. Thus, by using the alumina fibers or particles having the AlN layer formed on the surface as the reinforcing material, it is possible to obtain a metal-ceramics composite material which can have high strength at normal temperature and less decrease in strength at high temperature. Obtainable.

As a method for forming the AlN layer on the surface of the alumina fibers or particles, a method of mixing the alumina fibers or particles with carbon powder and heating them at a temperature of 1700 ° C. or higher in a nitrogen atmosphere was used. Although this does not completely form the AlN layer on the surface, it is a cheap and easy method, and the cost does not increase so much.

As a method for infiltrating aluminum or its alloy into a preform formed by using the alumina fibers or particles, a high pressure casting method was used. AlN on the surface
It is difficult for the alumina without forming the layer to sufficiently penetrate the matrix even in the high pressure casting, but in the case of the alumina fibers or particles of the present invention, the matrix is sufficiently spread in the high pressure casting.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A method for producing a metal-ceramic composite material of the present invention will be described. First, a predetermined amount of carbon powder is mixed with alumina fibers or particles (powder) as a reinforcing material, and the mixture is heated to 1700 ° C. in a nitrogen atmosphere. By heating at the above temperature, alumina fibers or particles having an AlN layer formed on the surface are obtained.

The obtained particles are used as they are, or particles obtained by mixing a predetermined amount of fibers with the particles are mixed with a binder, dried, and pressed into a predetermined shape with a mold or the like. Form a preform. The formed preform is placed in a mold for aluminum casting, and aluminum or its alloy which is heated and melted at a predetermined temperature is separately poured into the mold in which the preform is placed, and high-pressure casting is performed at a predetermined pressure to form an alumina fiber. Alternatively, a metal is permeated between the particles to produce a metal-ceramic composite material.

As mentioned above, the surface of the alumina, which is the reinforcing material, is A
If alumina fibers or particles having an IN layer are used,
A metal-ceramic composite material having high strength at room temperature and little decrease in strength at high temperature can be obtained.

[0015]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to specific examples of the present invention together with comparative examples.

(Example) (1) Preparation of Reinforcing Material As a reinforcing material, 100 parts by weight of alumina particles (A-21 manufactured by Sumitomo Chemical Co., Ltd., average particle size 40 μm) and 10 parts of carbon powder (MA-200RB manufactured by Mitsubishi Kasei Co., Ltd.) were used. By adding parts by weight and mixing, and heating at a temperature of 1700 ° C. in a nitrogen atmosphere, a reinforcing material having an AlN layer formed on the surface of alumina powder was produced.

(2) Formation of preform IPA and polyvinyl butyral (BL-1 manufactured by Sekisui Chemical Co., Ltd.) were added to the obtained particles, mixed and dried, and then filled in a mold (100 mm × 50 mm). And pressure 20
A preform (100 mm × 50 mm × 15 mm) was formed by applying a pressure of 0 kgf / cm ² for 3 minutes. The filling rate of the preform at this time was 42%.

(3) Preparation of metal-alumina composite material Diameter 50 mm x thickness 15 mm from the formed preform
Was cut out and set in a cylindrical aluminum casting mold (diameter 50 mm × height 50 mm). Separately, an aluminum alloy (JIS name AC7A) was placed in a graphite crucible for casting (# 2 manufactured by Nippon Crucible Co., Ltd.) and 750 ° C.
It was heated and melted. This molten aluminum alloy is poured into a mold with a preform set, and a punch bar is used for 50M.
A pressure of Pa was applied for 3 minutes, and a molten aluminum alloy was permeated between alumina particles to prepare a metal-alumina composite material.

(4) Evaluation A test piece was cut out from the obtained composite material and JIS R16
According to No. 01, the flexural strength was measured at normal temperature and at the temperatures shown in Table 1. Table 1 shows the results.

Comparative Example For comparison, a composite material was prepared and evaluated in the same manner as in Example except that alumina particles having no AlN layer on the surface were used as the reinforcing material. Table 1 shows the results.

[0021]

[Table 1]

As is clear from Table 1, in Examples, both room temperature strength and high temperature strength were higher than those of Comparative Examples. On the other hand, in the comparative example, the strength was significantly reduced at a high temperature as compared with the examples, and particularly at 400 ° C., which has the highest temperature, the strength was significantly reduced.

[0023]

As described above, according to the present invention, since the alumina fibers or particles having the AlN layer on the surface are used as the reinforcing material, the wettability with aluminum or its alloy is improved, the room temperature strength and the high temperature are improved. It has become possible to provide a metal-ceramics composite material which has higher strength than conventional ones and has less strength reduction at high temperatures. This allows
A metal-ceramic composite material having excellent strength, particularly strength performance at high temperature, has been obtained.

Claims (2)

[Claims] 1. A metal-ceramic composite material in which a base material, aluminum or its alloy, is impregnated into a preform composed of reinforcing alumina fibers or particles, and the alumina fibers or particles are formed on the surface of the composite material. A metal-ceramic composite material comprising alumina fibers or particles having an aluminum nitride layer. 2. A method for producing a metal-ceramic composite material, comprising forming a preform by using alumina fibers or particles having an aluminum nitride layer on the surface as a reinforcing material, and infiltrating aluminum or an alloy thereof into the preform. A method of forming an aluminum nitride layer on the surface of particles is to mix alumina fibers or particles with carbon powder, and mix the mixture in a nitrogen atmosphere for 17 minutes.
A method for producing a metal-ceramic composite material, which is a method of heating at a temperature of 00 ° C. or higher, and a method of infiltrating aluminum or its alloy is a high-pressure casting method.