JPH02197536A - Manufacture of metal-matrix composite material - Google Patents

Abstract

PURPOSE:To easily obtain the composite material of which short fibers are uniformly dispersed into a molten metal by immersing a composite material reinforced with short fibers or the like into the molten metal of a matrix metal and giving high frequency vibration to the composite material while a brush is brought into contact therewith. CONSTITUTION:A composite material 16 constituted of a metal reinforced compositely with fine short fibers or grains is fixed to a supporting matter 18 of ceramics or the like and is immersed to hold into the molten metal 22 of the matrix metal such as Al alloy. Bristles 26 of a heat-resistant brush 28 planted with the ones constituted of Al fibers, etc., are brought into contact with the composite material 16 to oscillate the brush 28 by an ultrasonic oscillator 30 via a horn 32. Together with this, the molten metal 22 is stirred with a propeller 34 and the short fibers or grains in the composite material 16 are dispersed into the molten metal 22. The short fibers or grains are uniformly dispersed in the condition of tight adhesion with the matrix metal, by which the composite material contg. no flaws such as void can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a metal matrix composite material, and more particularly to a method for producing the same.

2. Prior Art As a method for manufacturing a metal matrix composite material using fine short fibers or particles with a relatively low volume fraction as a reinforcing material, for example, in the 1980s,
As described on pages 396 to 399 of "Basics of Aluminum Materials and Industrial Technology" (edited by the Light Metals Association), published by the Light Metals Association in 2010, a molten matrix metal in a semi-molten state is stirred. Conventionally, a composite casting method in which a reinforcing material is added to the molten metal, and a powder metallurgy method in which a matrix metal powder and a reinforcing material are mixed and the mixture is sintered are known.

According to these methods, a molded body of the reinforcing material is formed, and compared to the pressure casting method in which a molten matrix metal is infiltrated into the molded body under pressure, fine reinforcement with a relatively low volume fraction is produced. It is possible to easily manufacture composite materials reinforced with materials.

Problems to be Solved by the Invention However, in the composite casting method, the reinforcing material cannot be dispersed in the molten matrix metal unless the reinforcing material has excellent wettability to the molten metal. Very fine reinforcing materials such as particles of 1 μm or less tend to form clusters, making it difficult to produce composite materials in which the reinforcing materials are uniformly dispersed. Furthermore, strict temperature control is required to maintain the molten metal in a semi-molten state, making it difficult to easily manufacture composite materials.

Furthermore, in the powder metallurgy method, it is difficult to produce a composite material that has excellent adhesion between the reinforcing material and the matrix metal and does not contain defects such as pores. It is difficult to mix the reinforcing material with the metal powder, making it difficult to produce a composite material in which the reinforcing material is uniformly dispersed. There is a problem in that short fibers are easily damaged during the process.

Furthermore, in the composite casting method, it is essential to stir the molten metal in a semi-molten state, and in the powder metallurgy method, it is necessary to compress the mixture of metal powder and reinforcing material.
For example, it is difficult to manufacture components made of composite materials that have complex shapes, such as components that include undercuts.

In view of the above-mentioned problems in the composite casting method and powder metallurgy method, the present invention aims to achieve a method in which fine short fibers or particles with a relatively low volume fraction are uniformly dispersed in a state in which they are in close contact with the matrix metal, and voids are formed. The purpose of the present invention is to provide a method that can easily produce a composite material that does not contain defects such as.

Means for Solving the Problems According to the present invention, the above-mentioned object is achieved by immersing a composite material made of a metal reinforced with fine short fibers or particles into a molten metal of a matrix metal; This is achieved by a method for manufacturing a metal matrix composite material, which includes bringing a heat-resistant brush into contact with the molten metal and stirring the molten metal while applying high-frequency vibration to the brush.

Effects and Effects of the Invention According to the present invention, a heat-resistant brush is brought into contact with the composite material, and the molten matrix metal is stirred while high-frequency vibrations are applied to the brush. The reinforcing material, i.e., short fibers or particles, is gradually released into the molten matrix metal by being gradually peeled off, and the reinforcing material is mixed with the molten matrix metal by being stirred with the molten metal. Even in the case of reinforcing materials with poor wettability, they are uniformly dispersed in the molten matrix metal without forming clusters. In addition, the molten matrix metal does not need to be in a semi-molten state as in the case of the composite cast method, but may be in a completely molten state, so strict temperature control etc. are not required, and therefore, compared to the case of the composite cast method, Composite materials can be easily manufactured using this method.

In addition, since the reinforcing material is mixed with the molten matrix metal by stirring immediately after it is released from the original composite material, the adhesion between the reinforcing material and the matrix metal is degraded and defects such as pores occur, compared to the powder metallurgy method. Composite materials that do not contain can be easily manufactured. Additionally, since the reinforcement is mixed with the matrix metal in a completely molten state, problems such as breakage of the reinforcement can be avoided as in the case of composite casting, where the reinforcement is mixed with solid metal powder. Furthermore, it can be mixed uniformly with the molten metal of the matrix metal, making it easier to produce a composite material in which the reinforcing material in its normal state is uniformly dispersed, compared to the case of composite casting.

Further, according to the present invention, it is possible to form a composite metal molten metal in which fine reinforcing materials with a relatively low volume fraction are uniformly dispersed, so that the composite metal molten metal can be simply poured into a mold for gravity casting, for example. By hot water solidification, it is possible to easily manufacture a composite material member having a complex shape and having reinforcing material uniformly dispersed throughout.

According to the results of experimental research conducted by the inventors of the present application, it has been found that when the vibration direction of the brush is along the direction of bristles, the reinforcement can be dispersed more evenly. According to one detailed feature of the invention, therefore, the brush is vibrated in a direction substantially along the direction of extension of its bristles.

Further, in the method of the present invention, the matrix metal of the composite material prepared in advance may be a metal of the same composition as the matrix metal in which it is immersed, or may be a metal of a different composition, In the former case, a composite material prepared in advance and the same matrix metal can be manufactured, and in the latter case, the composition of the matrix metal can be changed at the same time as the composite material is manufactured.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will be explained in detail below by way of example embodiments with reference to the accompanying figures.

Example 1 By compression molding silicon carbide whiskers (“Toka Whiskers” manufactured by Tokai Carbon Co., Ltd.), a volume ratio of approximately 30
Made of % silicon carbide whiskers 20X40X100m
A molded body having dimensions of m was formed. Next, the molded body was
After preheating to 50°C, as shown in FIG. Approximately 1000 k by the plunger 14 that fits into
A casting containing a composite material made of an aluminum alloy composite reinforced with silicon carbide whiskers with a volume ratio of 30% by pressurizing the molten metal to a pressure of g/C- and maintaining the pressurized state until the molten metal completely solidifies. was formed.

Next, the composite material is extracted from the casting by performing machining on the casting, and as shown in FIG. 5k maintained at
Molten metal 2 of aluminum alloy (JIS standard AC4C) of g
It was kept immersed in 2. Next, as shown in FIG. 2, the bristles of a heat-resistant brush 28, in which bristles 26 made of alumina fibers having a diameter of 10 μm are implanted on an alumina substrate 24, are brought into contact with the composite material 16, and the brush 28 is connected to an ultrasonic oscillator 30. 28kHz, 150W through the horn 32 to the board 24.
Vibration was applied in a direction perpendicular to the extending direction of the bristles 26, that is, in a direction along the extending direction of the bristles 26, and the molten metal 22 was simultaneously stirred by the propeller 34. In this case, all the silicon carbide whiskers were dispersed in the molten metal 22 after about 5 minutes had passed. A total of 10 composite materials were treated in the same manner, and then the molten metal 22 was further stirred for 30 minutes, and then the molten metal was allowed to solidify as it was.

Next, when the composite material thus formed was cut and its cross section was observed, it was found that silicon carbide whiskers accounted for approximately 10% by volume.
It was confirmed that the silicon carbide whiskers were uniformly dispersed throughout the composite material, and that the adhesion between the silicon carbide whiskers and the aluminum alloy was also good.

Also, under the same procedure and conditions as above, the volume ratio is approximately 10.
% of silicon carbide whiskers are uniformly dispersed, and by pouring the molten metal into a mold of a gravity casting device, the mold has dimensions of 150 mm in length, 90 mm in outer diameter, and 80 mm in inner diameter, A sleeve having a groove having a width of 10 mm and a depth of 2I11 was formed on the outer surface of the central portion in the longitudinal direction. Next, the thus formed sleeve was cut in the direction along the axis and in the direction perpendicular to the axis, and the cross sections were observed. It was found that silicon carbide whiskers were present throughout the sleeve at a volume ratio of about 10%. It was found that the silicon carbide whiskers were uniformly dispersed and that the adhesion between the silicon carbide whiskers and the aluminum alloy was good.

Embodiment 2 As shown in FIG.
A composite material was formed in the same manner and under the same conditions as in Example 1 above, except that the vibration was applied along the extending direction.

In this example as well, the volume ratio of silicon carbide whiskers is about 10.
%, but the uniformity of the dispersion state of silicon carbide whiskers was not so good in the composite material of Example 1.

Comparative Example A composite material was prepared in the same manner and under the same conditions as in Example 1, except that the composite material was loosened by manually driving the comparative example brush 28 rather than by vibrating it with an ultrasonic oscillator. Formed.

As a result, the composite material crumbled into large clumps at its weak points, making it impossible to manufacture a composite material in which silicon carbide whiskers were uniformly dispersed.

In addition, the brush 28 does not loosen the composite material, and the propeller 3
When an attempt was made to manufacture a composite material in the same manner by only stirring the molten aluminum alloy according to No. 4, the composite material did not loosen, and therefore, no silicon carbide whiskers were dispersed in the molten metal 22.

Example 3 By compression molding silicon carbide particles with an average particle size of 0.5μ, 20
A molded body with dimensions of x 40 x 100 m+s was formed. Next, after preheating the molded body to 600°C, the molded body was placed in the same mold as that used in Example 1, and an aluminum alloy (J
A molten metal of IS standard ACIA) is poured, the molten metal is pressurized to a pressure of approximately 1000 kg/cd with a plunger, and the pressurized state is maintained until the molten metal completely solidifies. A casting containing a composite material consisting of an aluminum alloy composite reinforced with particles was formed.

Next, the composite material was extracted from the casting by performing machining on the casting, and the composite material thus obtained was used, and an aluminum alloy (JIS'ML rated ACIA) at 750°C was used as the molten metal for the matrix metal. A total of eight composite materials were treated in the same manner and under the same conditions as in Example 1 above, except for the following.

Next, when the thus formed composite material was cut and its cross section was observed, silicon carbide particles with a volume fraction of 11% were uniformly dispersed throughout the composite material, and the adhesion between the silicon carbide particles and the aluminum alloy was also good. One thing was recognized.

Also, under the same procedure and conditions as above, the volume ratio is approximately 11.
A sleeve having the same dimensions and shape as the sleeve of Example 1 was formed by forming a composite molten metal in which % of silicon carbide particles were uniformly dispersed, and pouring the molten metal into a mold of a gravity casting device. When the sleeve was cut along the axis and in the direction perpendicular to the axis and the cross sections were observed, it was found that silicon carbide particles were uniformly dispersed throughout the sleeve at a volume percentage of about 11%. It was also confirmed that the adhesion between the silicon carbide particles and the aluminum alloy was good.

Although the present invention has been described in detail with reference to several embodiments above, the present invention is not limited to these embodiments, and various other embodiments may be made within the scope of the present invention. It will be obvious to those skilled in the art that this is possible.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a pressure casting process, FIG. 2 is a sectional view showing a state in which a composite material is manufactured according to an embodiment of the present invention, and FIG. 3 is an alternative method of vibrating a brush. FIG. 2 is an illustration showing two embodiments. 10... Molded body, 12... Mold, 14... Plunger. 16... Composite material, 18... Support, 20... Heater. 22... Molten aluminum alloy, 24... Substrate,
26... Hair, 28... Brush, 30... Ultrasonic oscillator, 32... Horn, 34... Propeller Figure 1

Claims (1)

[Claims] A composite material made of a metal reinforced with fine short fibers or particles is immersed in a molten matrix metal, a heat-resistant brush is brought into contact with the composite material, and high-frequency vibration is applied to the brush while the A method for producing a metal matrix composite material comprising stirring a molten metal.