JPS642471B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a composite material containing reinforcing materials such as fibers, fine wires, powders, whiskers, etc. in a matrix metal.

Fiber-reinforced metal materials (FRM), which have a matrix metal and are reinforced with high-tensile fibers such as metal, boron, or carbon, are known as composite materials. Various proposals have been made.

One of the manufacturing methods is to make sheets of fibers and matrix metal by metal spraying in a vacuum atmosphere, stack many sheets and press them at high temperature in a vacuum atmosphere, and then diffuse the matrix metal. A so-called diffusion bonding method (hot press method) is known in which sheets are bonded to each other to produce a fiber-reinforced metal material. With this manufacturing method, a high-quality fiber-reinforced metal material can be obtained, but the manufacturing cost and manufacturing time are large, and mass productivity is lacking, making it difficult to use in general industry.

Another known method for manufacturing fiber-reinforced metal materials is a permeation impregnation method, mainly an autoclave method. In this permeation impregnation method, the fibers are loaded into a container, the container is kept in a vacuum state, and one end ^of the container is immersed in molten matrix metal. A fiber-reinforced metal material is manufactured by applying fluid pressure with gas and impregnating the molten metal between the fibers in the container. With this manufacturing method, a high-density fiber-reinforced metal material can be obtained, but due to insufficient pressure, a fiber-reinforced metal material with a combination of materials with poor wettability cannot be manufactured. As a countermeasure to this, the matrix metal is aluminum or its alloys, etc.
When the reinforcing material is alumina fiber, several percent of lithium is added to the matrix metal to improve the wettability between the matrix metal and the fibers.

In yet another method for manufacturing a fiber-reinforced metal material, a mold is filled with fibers, then a molten matrix metal is poured into the mold, and a plunger element engaging the mold is used to 1000 ml of molten metal in the mold
A so-called high-pressure casting method is known in which a fiber-reinforced metal material is obtained by pressurizing at a high pressure of Kg/cm ² or higher to impregnate molten metal between the fibers and solidifying the matrix metal under pressure. There is. In this high-pressure casting method, when the molten metal impregnates between the fibers, the temperature of the fibers is lower than the melting point of the matrix metal, so the molten metal that has penetrated between the fibers is cooled by the fibers. It becomes a semi-molten state or a solid state. For this reason, even if the molten metal is pressurized at a high pressure of 1000 kg/cm ² , the impregnation pressure of the molten metal between the fibers is low, making it impossible to obtain a material with sufficient strength, and the high impregnation resistance causes the fibers to buckle. It is difficult to obtain a homogeneous material because of changes in density and density. Furthermore, even with this manufacturing method, it is difficult to composite the fiber and matrix metal unless the combination has good wettability.

In view of the above-mentioned drawbacks of conventional methods for manufacturing composite materials such as fiber-reinforced metal materials, the present invention provides a method for manufacturing composite materials that can efficiently manufacture high-quality composite materials at relatively low cost. is intended to provide.

According to the present invention, the purpose is to heat a reinforcing material with a porous structure to a temperature higher than the melting point of the matrix metal outside the mold, and place the reinforcing material inside the mold in a state where it is supported by a stand from the bottom of the mold. by placing it so that it is spaced apart from both the bottom and side surfaces of the mold,
By pouring molten matrix metal into the mold to a height at which the reinforcing material is buried, the porous reinforcing material is completely filled with the molten matrix metal, and the reinforcing material in the porous structure is completely filled with the molten matrix metal. A method for manufacturing a composite material, characterized in that the molten metal in the mold is pressurized by a plunger that engages with the part, impregnating the reinforcing material with the molten metal, and solidifying the molten metal in the pressurized state. It will be achieved.

According to the manufacturing method of the present invention, the reinforcing material is heated to a temperature higher than the melting point of the matrix metal by any means outside the mold, and in the heated state is placed inside the mold separated from both the bottom and side surfaces of the reinforcing material. In this state, molten matrix metal is poured into the mold, and the reinforcing material is completely cast in the molten matrix metal, forming a layer of molten matrix metal on the mold wall. The reinforcing material is kept in a more insulated and warmed state, which is then pressurized by the plunger, so that the reinforcing material is heated to a temperature above the melting point of the matrix metal until the molten matrix metal has sufficiently penetrated into its interior and it is sufficiently pressurized. This results in a good quality composite material with good penetration of the matrix metal within the reinforcement.

In addition, in the conventional high-pressure casting method, the reinforcing material is not preheated, so a composite material with a healthy structure can only be obtained if the volume fraction of the reinforcing material is around 20 to 30% at most. In contrast to staying with things;
According to the manufacturing method of the present invention, the volume fraction of the reinforcing material can be increased to 50% or more as shown in the examples described below, and a composite material with superior mechanical strength compared to conventional materials can be produced. Obtainable.

Next, an example will be described.

Example 1 As shown in Figures 1 and 2, the length
A 100 mm alumina fiber 1 (fiber diameter 20μ, FP fiber manufactured by Dupont) was oriented in one direction, formed to have a volume ratio of 50%, opened at one end, length 130 mm, height 10 mm, Square cylindrical case 2 made of stainless steel (JIS standard SUS310S) with a width of 20 mm
loaded inside. The alumina fibers 1 were shorter than the case 2, and the alumina fibers 1 were loaded into the case 2 so that an air chamber 3 was formed at the closed end of the case 2. The alumina fiber 1 filled in the case 2 is heated to 750°C, and as shown in FIG. Pure aluminum molten metal at 850°C was quickly poured into the mold and pressurized at 1000 Kg/cm ² by plunger element 6 at 200°C. This pressurized state was maintained until the molten aluminum solidified completely.

After the molten metal in the mold has completely solidified, it is taken out from the mold, the aluminum around the case 2 is removed by cutting, the case 2 is taken out, and a composite material made of alumina fiber 1 and pure aluminum is further removed from the case. I took it out. From observation of the composite material taken out, it was found that an aluminum solidified body containing air bubbles formed by compressing the air between the alumina fibers and the air existing in the air chamber was cast in the air chamber 3. Therefore, the molten metal flows relatively vigorously in one direction from the open end of the case 2 toward the closed end due to the pressure applied by the plunger element.
It is presumed that as a result, the molten metal pushed out the air between the alumina fibers and entered between them, and the air was also forced into the air chamber 3 of the case 2. Incidentally, the solidified body containing air bubbles was removed as a draft part.

A tensile test of the composite material produced in the manner described above in the 0 degree fiber orientation direction showed a tensile strength of 55 to 60 Kg/mm ² .

FIG. 4 is a scanning electron micrograph of the tensile fracture surface of the composite material. As is clear from this photograph, the fibers of the composite material do not pull out due to tension, and as a result, a composite material exhibiting high tensile strength is obtained.

As a comparative example, alumina fiber was heated to 450℃.
℃, 550℃, 650℃, 750℃ and 900℃ to produce composite materials. The composite materials thus obtained were subjected to a tensile strength test under the same conditions. The results are shown in FIG. This graph also shows that the tensile strength of the composite material increases as the heating temperature of the fiber increases, and it is 650
It can be seen that it is saturated at about ~750℃.

FIG. 6 is a scanning electron micrograph of the tensile fracture surface of a composite material obtained by heating alumina fibers to 450°C. As can be seen from the comparison between FIG. 4 and FIG. 6, when the fibers were heated to about 450°C, the fibers pulled out, but when the fibers were heated to 750°C, the fibers did not pull out.

Further, a composite material manufactured in the same manner as in Example 1 was subjected to a four-point bending fatigue test in the 0° fiber orientation direction. The results of this test are shown in FIG.

In this graph, the solid line shows the test results of the composite material manufactured by the method of the present invention, and the broken line shows the test results of the composite material manufactured by the method of the present invention, and the broken line shows the test results of the composite material manufactured by the method of the present invention.
AC8P) is the same test result. As is clear from this graph, the composite material produced by the method of the present invention exhibited excellent mechanical properties with a 10 ⁷ cycle strength of 35 Kg/mm ² .

Example 2 The same stainless steel case as in Example 1 was made, and the volume ratio was 60.
% high elasticity type carbon fiber (Toray trading card)
Filled with M40) and boron fiber (manufactured by AVCO),
After replacing the inside of the case with oxygen, the fibers were immersed in 750°C molten magnesium, and the molten metal heated the fibers to 750°C. Thereafter, a composite material of carbon fibers, boron fibers, and magnesium was manufactured in the same manner as in Example 1.

A composite material of magnesium and high modulus type carbon fiber has a tensile strength of 80
It showed a tensile strength of Kg/ ^mm2 . A composite material of magnesium and boron showed a tensile strength of 130 Kg/mm ² in a tensile test in the 0 degree fiber orientation direction.

[Brief explanation of drawings]

1 to 3 are explanatory diagrams showing the manufacturing process of manufacturing a composite material by the method of the present invention, FIG. 4 is a scanning electron micrograph of the tensile fracture surface of the composite material obtained by the method of the present invention, and FIG. The figure is a graph showing the relationship between the fiber heating temperature and the tensile strength of the composite material. Figure 6 is a scanning electron micrograph of the tensile fracture surface of a composite material manufactured without heating the fibers in the method of the present invention. , FIG. 7 is a graph showing the results of a four-point bending fatigue test. 1~Alumina fiber, 2~Case, 3~Air chamber,
4~type, 5~stand, 6~plunger element.

Claims (1)

[Claims] 1. A reinforcing material with a porous structure heated outside the mold above the melting point of the matrix metal is placed inside the mold in a state where it is supported by a stand from the bottom of the mold, so that the bottom surface of the mold and The reinforcing material having the porous structure is made of the molten matrix metal by placing the reinforcing material in the mold so as to be spaced apart from any of the side surfaces, and pouring molten matrix metal into the mold to a height that embeds the reinforcing material in the mold. Completely cast,
The molten metal in the mold is pressurized by a plunger that engages with a part of the mold to impregnate the porous structure of the reinforcing material, and the molten metal is solidified under pressure. A method for manufacturing a composite material.