JPH03114649A - Production of metal-base reinforced material - Google Patents

Abstract

PURPOSE:To prevent the development of casting blow hole in inner part of a product and to produce a metal-base reinforced material having uniform mechanical strength from the outer circumference to the inner part of product by arranging heating means at a base material metal introducing part in a die and pressing the base material metal into the die while heating. CONSTITUTION:To the introducing part 3 for supplying the base material metal, a pipe-shaped block 7 preheated at the temp. higher than the m.p. of the base material metal 5 by the prescribed temp. is fitted. SiC whisker preforming body is laid in the die 1 and Al alloy is introduced into the die 1 to impregnate the preforming body with the Al alloy. Then, after holding the pressurizing condition at the prescribed pressure, the casting body is taken out from the die to produce the metal base composite material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a metal matrix composite material using a high-pressure solidification casting method.

[Prior Art] Conventionally, a high-pressure solidification casting method (squeeze casting method) has been used as a method for manufacturing metal matrix composite materials. In the squeeze casting method, a preform made of reinforcing material such as ceramic whiskers is placed in the cavity of a casting mold in advance, and then molten base metal (molten metal) is poured into the preform at a rate of several tens of meters per second. It is press-fitted and cast at a speed of 100 mm. The metal matrix composite obtained by this method has mechanical properties such as high strength and excellent wear resistance.

FIG. 3(a) is a cross-sectional view schematically showing a part of an apparatus used in a conventional method for manufacturing a metal matrix composite material. 2 in the diagram
1 indicates a mold. The mold 21 consists of two thick metal plates 21a,
21. When the two metal plates 21a and 21b are put together, a cavity 22 and an introduction part 23 for supplying the molten base metal are formed. A preformed body (not shown) made of a reinforcing material such as ceramic whiskers is placed in the cavity 22 in advance. Further, a plunger 24 is inserted into a flow section 25 communicating with the introduction section 23, and molten base metal is supplied from a molten metal supply source (not shown).

When manufacturing metal matrix composites using such equipment,
Particularly when manufacturing a preform with a complex shape, a pressure above a certain level is required to sufficiently impregnate the entire preform with molten metal. In other words, depending on the product shape,
It is necessary to ensure the predetermined pressure necessary for impregnation. on the other hand,
There are certain limits to the ability of the drive to push plunger 24.

Therefore, it is generally necessary to make the cross-sectional area of the introduction part 23 smaller than the cross-sectional area of the cavity 22.

On the other hand, the purpose of using the high-pressure solidification casting method is to prevent defects (so-called cavities) from occurring inside the metal matrix composite material obtained. Therefore, in order to sufficiently impregnate the entire preform with molten metal, it is necessary to rapidly supply the required amount of molten metal to the cavity 22 until it completely solidifies.

[Problem to be solved by the invention] However, in the conventional manufacturing method, the introduction part 23
is narrow, and the temperature drop of the molten metal passing through it is large.

For this reason, the molten metal completely solidifies in the introduction section 23 before the molten metal sufficiently penetrates the entire preform. As a result, as shown in FIG. 3(b), the completely solidified base metal 26 separates from the molten base metal 27.
The introduction section 23 is closed. As a result, the molten metal cannot further flow into the cavity 22, and the pressurized state cannot be maintained. As a result, cavities occur inside the
Mechanical strength such as tensile strength of the product decreases.

The present invention has been made in view of the above, and provides a method for manufacturing a metal matrix composite material that can prevent the formation of blowholes inside the product and can produce a metal matrix composite material that has excellent mechanical strength. The purpose is to provide

[Means for Solving the Problems] The present invention provides a method for manufacturing a metal matrix composite material in which a molten base metal is press-fitted into a mold into a preformed body made of a half-breasted main reinforcement material, in which the heating means is It is characterized in that it is provided in a base metal introduction part of a mold, and press-fits into the mold while heating the base metal.

[Function] According to the method for manufacturing a metal matrix composite material of the present invention, the base metal introduction part of the casting mold is heated to maintain the molten state of the base metal while pressurizing the molten metal into the mold, and pre-heating the base metal introduction part of the casting mold. The molded body is impregnated with molten metal.

Therefore, the temperature drop of the base metal at the base metal introduction portion is reduced, and the molten state of the base metal is maintained. As a result, the pressurized state is maintained until the entire preform is covered with the base metal, and a complex-shaped product without internal defects such as blowholes can be obtained.

[Examples] Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view schematically showing a part of an apparatus used in a method for manufacturing a metal matrix composite material according to an example of the present invention. In the figure, 1 indicates a mold. Mold 1 consists of two thick metal plates 1
a, lb, and when two metal plates are put together, a cavity 2 and an introduction part 3 that supplies the molten base metal.
It is designed to form a A preformed body made of a reinforcing material such as ceramic whiskers is placed in the cavity 2 in advance. The introduction section 3 includes a flow section 6 into which the plunger 4 is inserted and through which the base metal 5 in a molten state flows.
It is communicated with. A plunger 4 is inserted into the flow portion 6 . Furthermore, a pipe-shaped block 7 that has been preheated to 200 to 300° C. or higher than the melting point of the base metal 5 is fitted into the introduction portion 3 . The pipe-shaped block 7 heats the molten metal press-fitted by the plunger 4 in the introduction section 3 . Here, as a heating means for heating the molten metal through the introduction section 3, a general heating means such as a heater may be attached near the introduction section 3.

Using this apparatus, a metal matrix composite material was manufactured in the following manner.

Here, SiC whiskers were used for the preform.

Further, an aluminum alloy (AC8A) was used as the base metal.

First, it was placed in a molded body 1 for forming a SiC whisker child. Next, aluminum alloy was introduced into the mold 1 at a feed rate of 100 mm/see and a feed temperature of 800° C. to impregnate the preform. At this time, the preformed body was also heated to 800°C in advance. Then 80 C1kg/mm
After maintaining the pressurized state at a pressure of 2 for 2 minutes, the cast body was taken out from the mold to produce a metal matrix composite.

The strength of each part of the obtained metal matrix composite was examined. The results are shown in Figure 2. In addition, the ratio of the blow hole area to the product volume of the obtained metal matrix composite was investigated. The results are shown in Table 1 below. In addition, the strength was measured by a tensile test, and the proportion of the blowhole area was investigated by X-ray photography.

Comparative Example A metal matrix composite material was produced in the same manner as in the example using the apparatus shown in FIG. 3(a). Note that the reinforcing material and base metal of the preform were the same as in the examples.

The ratio of the blow hole area to the volume of the obtained metal matrix composite product was investigated in the same manner as in the examples. The results are shown in FIG. 2 for strength and in Table 1 below for the proportion of porosity area.

FIG. 2 is a graph showing the relationship between the distance from the center of the product and the strength. Here, the horizontal axis is the distance from the center of the product, and the vertical axis is the strength. Furthermore, white circles in the figure represent products obtained by the method of the present invention, and black circles represent products obtained by the conventional method.

As is clear from Table 1, the metal matrix composite material (Example) produced by the method of the present invention had no blowholes at all. On the other hand, the metal matrix composite material (comparative example) manufactured by the conventional method had cavities.

Moreover, as is clear from FIG. 2, the metal matrix composite material manufactured by the method of the present invention had substantially uniform strength from the center to the outer periphery of the product. On the contrary,
Metal matrix composites manufactured by conventional methods have low strength due to the presence of cavities in the center.

[Effects of the Invention] As explained above, the method for producing a metal matrix composite material of the present invention prevents the formation of blowholes inside the product and produces a metal matrix composite material that has uniform mechanical strength from the outer periphery to the interior of the product. material can be manufactured.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view schematically showing a part of the apparatus used in the method for manufacturing a metal matrix composite material of the present invention, and Fig. 2 is a graph showing the relationship between the distance from the center of the product and the strength. , Figure 3 (
a) and FIG. 3(b) are cross-sectional views schematically showing a part of an apparatus used in a conventional method for manufacturing a metal matrix composite material. DESCRIPTION OF SYMBOLS 1...Mold, 2...Cavity 3...Introduction part, 4...Plunger 5...Base metal, 6...
Flow section, 7...pipe-shaped block.

Claims (1)

[Claims] In a method for producing a metal matrix composite material, in which a molten base metal is press-fitted into a mold into a preformed body made of a reinforcing material, a heating means is provided in the base metal introduction part of the mold, and the base metal is heated. A method for producing a metal matrix composite material, comprising press-fitting the material into the mold while heating it.