JPH09324229A - Production of titanium carbide particle dispersion type metal-matrix composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the process without deteriorating the characteristics of the obtd. composite material in the method for producing a titanium carbide particle dispersion type metal matrix composite and to reduce the cost. SOLUTION: This producing method is constituted in such a manner that titanium powder, carbon powder and aluminum powder or aluminum alloy powder are mixed, this mixture is formed into a formed body having a prescribed shape, and then, this formed body is heated at 900 to 1800 deg.C in an inert atmosphere. In this case, in the mixture, the titanium powder and carbon powder are allowed to exist in a ratio by which titanium carbide is stoichiometrically formed, and the aluminum powder or aluminum alloy powder are allowed to exist by >=60wt.% expressed in terms of aluminum to the total weight of the titanium powder and carbide powder.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a metal matrix composite material (MMC), and more particularly to a method for producing a titanium carbide particle-dispersed metal matrix composite material.

[0002]

2. Description of the Related Art Titanium carbide particle-dispersed metal matrix composite materials are those in which hard fine particles of titanium carbide (TiC) are dispersed in a metal matrix to strengthen the matrix. In such a titanium carbide particle-dispersed metal-based composite material, since titanium carbide has a very high hardness, if the particle size of titanium carbide particles is large, it becomes difficult to process the MMC. Therefore, the titanium carbide particles have a particle size of 1
Fine particles of micron or smaller are effective for improving workability, but it is difficult to make the titanium carbide particles into such fine particles by the conventional method for producing a titanium carbide particle-dispersed metal-based composite material. It was

In order to solve such a problem, Japanese Patent Laid-Open No.
In Japanese Patent Laid-Open No. 17165, there has been proposed a method for producing a titanium carbide particle-dispersed metal matrix composite material in which particles of titanium carbide are made fine. This method uses titanium carbide particles in-situ
The titanium powder, carbon powder, and aluminum powder are uniformly mixed to form a compact, which is impregnated in molten aluminum and then heated to produce titanium carbide particles in the compact. And finally, the step of dissolving the molded body in a molten aluminum.

According to this method, the molded body composed of titanium powder, carbon powder and aluminum powder is porous,
By impregnating this molded body with molten aluminum, the voids in this molded body are filled with aluminum. When this is heated in an inert atmosphere, titanium carbide particles are generated in the molded body, but titanium and carbon chemically react with each other by diffusion in the state where aluminum is present around them, so that they are in direct contact with each other. Coarsening and agglomeration of the produced titanium carbide particles are suppressed as compared with the case of chemically reacting with, and as a result, finely dispersed titanium carbide particles are formed.

[0005]

However, in this conventional method, the steps of forming a molded body from powder, impregnating in molten aluminum, heating, and melting in molten aluminum are required, so that the cost is low. There is a problem of being expensive. It is an object of the present invention to provide a method for producing a simple titanium carbide particle-dispersed metal matrix composite material that enables cost reduction without impairing the properties of the obtained titanium carbide particle-dispersed metal matrix composite material. To do.

[0006]

In order to solve the above problems, according to the first invention, titanium powder, carbon powder and aluminum powder or aluminum alloy are mixed,
In the method for producing a titanium carbide particle-dispersed metal-based composite material, which comprises molding the mixture into a molded product having a predetermined shape, and then heating the molded product at 900 to 1800 ° C. in an inert atmosphere. In, the titanium powder and the carbon powder are present in a stoichiometric ratio to form titanium carbide,
In addition, aluminum powder or aluminum alloy powder is present in an amount of 60% by weight or more in terms of aluminum based on the total weight of titanium powder and carbon powder.

In order to solve the above problems, according to the second invention, titanium powder, carbon powder and aluminum powder or aluminum alloy powder are mixed, and this mixture is molded into a molded product having a predetermined shape. Then, this molded body is heated at 900 to 1800 ° C in an inert atmosphere to produce pellets, and then the pellets are melted and dispersed in a molten aluminum powder or aluminum alloy powder. In the method for producing a metal-based composite material, titanium powder and carbon powder are present in the mixture in a stoichiometric ratio to form titanium carbide, and aluminum powder or aluminum alloy powder is the total weight of titanium powder and carbon powder. On the other hand, 60% by weight or more of aluminum is present.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The size of titanium powder, carbon powder, aluminum powder or aluminum alloy powder used in the method of the present invention may be any size as long as it is not coarse, but a homogeneous composite material. In order to obtain the above, those having an average particle size of about 0.1 to 500 μm are preferable.

Any aluminum alloy may be used as long as it can form a matrix in a composite material, and examples thereof include an Al-12 wt% Si alloy.

In the method of the present invention, when these powders are mixed to form a mixture, the titanium powder and the carbon powder are mixed in a stoichiometric ratio to form titanium carbide. That is, the titanium powder and the carbon powder are mixed in a weight ratio of about 4: 1. Further, the amount of aluminum powder or aluminum alloy powder to be mixed is 60% by weight or more in terms of aluminum based on the total weight of titanium powder and carbon powder.

When synthesizing titanium carbide particles in-situ as described in the above-mentioned JP-A-6-17165, the size of the particles is large at the maximum temperature reached by the shaped body during the synthesis. To be affected. The reaction that produces titanium carbide from titanium and carbon is an exothermic reaction, and the maximum temperature reached during synthesis rises to around 2500 ° C. At such a high temperature, the titanium carbide produced becomes coarse and fine particles cannot be obtained. Therefore, as described in the above publication, it was necessary to synthesize carbonized particles after impregnating a mixture of powders into a molten aluminum and dispersing the powders.

However, as in the method of the present invention, when the content of aluminum in the powder mixture is 60% by weight or more, fine titanium carbide particles can be obtained without causing such a problem. That is, as the content of aluminum in the molded body increases, the heat capacity of aluminum also increases, and the heat capacity of the molded body itself also increases. Then, the maximum temperature reached during the synthesis of titanium carbide is also lowered, and fine particles can be formed.

The particle size of the obtained titanium carbide is also influenced by the temperature rising rate when heating the molded body. That is, if the temperature rising rate is high, even if aluminum is present in the molded body, the temperature becomes high temporarily or locally, resulting in a large particle size. This heating rate varies depending on the content of aluminum present in the compact, but generally, if the aluminum content is high, particles having an acceptable particle size can be obtained even if the heating rate is high. On the contrary, if the aluminum content is small, it is necessary to slow down the heating rate. Generally, with the aluminum content of 60% by weight or more, the heating rate may be 1 to 50 ° C./min.
C./min. Is preferred.

The heating temperature of the molded body varies depending on the size of the molded body and the heating time, but it may be a temperature sufficient to cause the synthesis reaction of titanium carbide, that is, 900 ° C. or higher,
Also, if this temperature is too high, the above problems occur,
Since fine particles cannot be obtained, it is preferably 1800 ° C or lower. Further, it is preferable to keep the molded body at the heating temperature for 5 seconds or more so that the center of the molded body is sufficiently heated in this temperature range.

As described above, by adjusting the content of aluminum in the powder mixture to a predetermined value or more, fine titanium carbide particles can be obtained by heating the mixture without impregnating it in the molten aluminum. It can be simplified and the manufacturing cost can be significantly reduced. Further, by dissolving / dispersing the obtained molded body in the molten aluminum, it is possible to manufacture a component having a complicated shape.

[0016]

【Example】

Example 1 8 g of titanium powder (average particle size 50 μm), 2 g of carbon powder (average particle size 10 μm) and 10 g of aluminum powder (average particle size 50 μm) were uniformly mixed and molded into a mold as shown in FIG. A disk-shaped molded body 1 having a diameter of 30 mm and a height of 10 mm as shown in the drawing was molded. Then, as shown in FIG. 2, the molded body is placed in a heating device 2 and heated to 1200 ° C. at a heating rate of 1, 2, 5, 10, 20 and 50 ° C./min by a heater 3 in an argon gas atmosphere, After heating for 10 seconds to cause an exothermic reaction, the mixture was cooled.

After cooling, each molded body was cut and the internal structure was observed. As a result, a large number of fine particles were deposited inside each molded body, and the measurement results of the average particle diameter of these fine particles are shown in FIG. 3 shows. As is clear from FIG. 3, 1 to 20 ° C. /
The particles precipitated in the molded body heated at a heating rate of 1 minute had a particle size of 1 micron or less. On the other hand, the particles precipitated in the molded body heated at a heating rate of 50 ° C./min were several times as large as the above particles, and some of them were 5 to 10 μm. When these precipitated particles were identified by an X-ray diffraction method, it was confirmed to be titanium carbide.

Example 2 After heating a molded body in the same manner as in Example 1 except that heating was performed at a temperature rising rate of 2 ° C./minute to a final temperature of 900 to 1800 ° C. (interval of 100 ° C.), the inside of each molded body was heated. The tissue was observed. The particles precipitated inside the molded body were confirmed to be titanium carbide by the X-ray diffraction method, and the average particle size of these particles is shown in FIG.
It was found that the titanium carbide particles precipitated in any of the compacts were fine, but the particle size was 1 micron or less at a temperature of 900 to 1500 ° C., which was preferable. Then, the titanium carbide particle-dispersed aluminum pellets which could be well synthesized were put into a molten aluminum at 750 ° C. and a molten aluminum-5 wt% copper, and the pellets were easily dissolved to uniformly disperse the titanium carbide particles. It was possible to manufacture MMC.

Example 3 For 8 g of titanium powder (average particle size 40 μm), 2 g of carbon powder (average particle size 20 μm) and 5, 6, 7, 8, 10, 15, 20 g (mixture of titanium powder and carbon powder). 50 to 200 by weight
%) Aluminum powder (average particle size 80 μm) was uniformly mixed and mold-molded to form a molded body. After heating the molded body in the same manner as in Example 1 except that the molded body was heated to 1200 ° C. at a temperature rising rate of 5 ° C./minute, the structure inside each molded body was observed. The particles deposited inside the molded body were confirmed to be titanium carbide by X-ray diffraction method, and the average particle size of these particles is shown in FIG. Further, FIGS. 6 and 7 show SEM photographs of molded bodies having aluminum powder contents of 5 g and 10 g, respectively. As shown in FIG. 7, a large number of fine titanium carbide particles having a particle size of 1 micron or less were precipitated in the molded product mixed with 6 to 20 g of aluminum powder. Meanwhile, 5g
As shown in FIG. 6, a large number of particles are precipitated in the molded body mixed with the aluminum powder, but the particle size is 5 to 10 times as large as the above, and in some places lumps of a ceramic-like substance. (This was also confirmed to be titanium carbide by the X-ray diffraction method). From this result, it was found that in order to deposit fine titanium carbide particles, it is necessary to mix the aluminum powder with the mixture of titanium powder and carbon powder in an amount of 60% by weight or more.

Next, the titanium carbide particle-dispersed aluminum pellets which could be well synthesized were placed in a molten aluminum at 700 ° C. and a molten aluminum-1.5 wt% magnesium, and the pellets were easily dissolved to give titanium carbide particles. It was possible to produce uniformly dispersed MMC. Further, when the same experiment was performed except that a molded body having a height of 7.5 mm was molded using 6 g of titanium powder and 1.5 g of carbon powder, the same result was obtained. Furthermore, instead of aluminum powder, aluminum-12 wt%
Similar results were obtained when a silicon alloy powder was used.

[0021]

INDUSTRIAL APPLICABILITY In the method for producing a titanium carbide particle-dispersed metal-based composite material, the steps can be simplified and the cost can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a schematic view of a molded body of a metal matrix composite material manufactured by the method of the present invention.

FIG. 2 is a schematic view showing a heating process of a molded body of a metal matrix composite material.

FIG. 3 is a graph showing the relationship between the temperature rising rate when heating a molded body of a metal-based composite material and the average particle diameter of titanium carbide particles obtained.

FIG. 4 is a graph showing the relationship between the heating temperature when heating a molded body of a metal-based composite material and the average particle size of titanium carbide particles obtained.

FIG. 5 is a graph showing the relationship between the aluminum content in a molded body of a metal-based composite material and the average particle size of titanium carbide particles obtained.

FIG. 6 is a photograph replacing a drawing, which shows a morphology of titanium carbide particles in the obtained metal matrix composite material when the aluminum content in the molded body is 50% by weight.

FIG. 7 is a photograph replacing a drawing showing a morphology of titanium carbide particles in the obtained metal matrix composite material when the aluminum content in the molded body is 100% by weight.

[Explanation of symbols]

 1 ... Molded body 2 ... Heating device 3 ... Heater

Claims (2)

[Claims] 1. A titanium powder, a carbon powder and an aluminum powder or an aluminum alloy powder are mixed, the mixture is molded into a molded product having a predetermined shape, and the molded product is then heated in an inert atmosphere at 900 to 1800 ° C. Heating, wherein the titanium powder and the carbon powder are present in the mixture in a stoichiometrically forming titanium carbide, and the aluminum powder or aluminum alloy powder is relative to the total weight of the titanium powder and the carbon powder. A method for producing a titanium carbide particle-dispersed metal matrix composite material, which is present in an amount of 60% by weight or more in terms of aluminum. 2. Titanium powder, carbon powder and aluminum powder or aluminum alloy powder are mixed, the mixture is molded into a molded product having a predetermined shape, and the molded product is then heated in an inert atmosphere at 900 to 1800 ° C. The method comprises heating to produce pellets, and then dissolving and dispersing the pellets in a molten aluminum powder or aluminum alloy powder, wherein titanium powder and carbon powder stoichiometrically form titanium carbide in the mixture. A titanium carbide particle-dispersed metal-based composite material, characterized in that the aluminum powder or aluminum alloy powder is present in a proportion of 60% by weight or more in terms of aluminum based on the total weight of titanium powder and carbon powder. Manufacturing method.