JPS62142733A - Manufacturing method of fiber reinforced metal composite material - Google Patents

Abstract

PURPOSE:To obtain a fiber-reinforced metallic composite body always free from abnormal segregation and having homogeneous characteristics, by setting whisker preforms in a preheated insert metal mold, by inserting the above in a mold, and by pouring under pressure a molten matrix metal into the above preforms. CONSTITUTION:The whisker preforms 1 which are to be a fibrous skeleton and consist of SiC, Si3N4, etc., are set in the preheated insert metal mold 5, and said metal mold 5 is inserted in the mold 2 and disposed above the lower punch 6. It is desirable that the heating of the mold 2 is continued via a heating system attached to the mold 2 during the course of infiltration. Successively, the melt 3 of matrix metal such as Al, etc., is poured into the mold 2, which is pressurized by means of a plunger 4 from above so as to infiltrate the melt 3 only from the surface of the preforms 1 in the direction of arrows. After the melt 3 is sufficiently infiltrated into the whole of the preform structure, solidification is carried out while maintaining the pressure, so that desired fiber-reinforced metallic composite material can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an improved method for producing a fiber 11:reinforced metal) 11 composite material by a pressure casting method.

[Conventional technology]

The whiskers, which are composed of sword-shaped medium crystals such as SiC, SiJN 4, or graphite, have excellent physical properties in terms of specific strength, specific modulus, heat resistance, and chemical stability. In particular, it is used as a composite reinforcing material for light metals such as AQ.

Pressure casting is known as an effective means for manufacturing fiber-reinforced metal composites using this type of whiskers. The pressure casting method involves assembling preformed whisker aggregates brifono 1 as shown in Figure 1:
Cast 11′ as a boner! Place the molten metal 3 in the matrix metal 4-1) and apply pressure with the plunger 4 to impregnate and solidify the inside of the tissue.This method is used. The most important operational conditions in this case are the matrix gold 111 throughout the impregnation process.
It is to maintain the molten metal state normally. During the impregnation process, solidification of trisox metal in molten or cold water impedes smooth penetration into the glyph 4-me structure;
This means that property defects such as cracks of <4, extreme shrinkage deformation of the composite, and heterogeneity of the composite structure should be eliminated.

In addition, in order to ensure smooth impregnation, the conventional method was to infiltrate the molten metal from the top surface of the whisker blank and the gold side in the direction of the arrows as shown in Figure 1. This causes a phenomenon in which gas components occluded within the microstructure or segregation of components due to certain reactions that occur during impregnation with a solution are trapped in the composite central portion, and rather causes tissue defects.

[Problems that need to be invented or solved]

In addition to the above phenomenon, in order to prevent solidification of the matrix metal, means for preheating the mold and the pref +-11 are commonly used. However, the temperature of the mold cannot be raised sufficiently due to equipment constraints, and is insufficient to maintain a normal molten metal state throughout the impregnation process.

On the other hand, no effective countermeasures have been taken so far regarding the structural segregation caused by the entire surface penetration of the molten metal into the brief A--me.

The present invention has been made to solve these problems simultaneously.

[Means for solving problems]

The method for producing a fiber-reinforced metal composite material provided by the present invention includes placing whisker blanks 4-1 as fibers in a mold, and pouring a 7-trix metal molten metal into the mold. When forming a composite by the pressure casting method, the main structural feature is that the whisker preform is set in a preheated inner mold and inserted into the mold with four holes.

Hereinafter, the present invention will be explained in detail with reference to the explanatory diagram of FIG.

First, a whisker preform l that will become a fiber skeleton is set in a preheated insert mold 5. The whisker preform is an aggregate of short fibers formed by a dry or wet method after decomposing generated whiskers such as SiC, 5izN4, or graphite, and is formed into an outer shape that matches the inner shape of the inner mold 5. . Insertion 5 The mold 5 is made of a hard metal with excellent thermal conductivity, such as tool steel, and the inner surface is formed to follow the final shape such as a cylinder, inverted cone, or uneven I/4, and the outer surface is made of a hard metal with excellent thermal conductivity, such as tool steel. It is designed and processed so that it comes into close contact with the inner wall of the mold 2 when it is young. In addition to the integrated structure, this
It can also be made into a separate split type structure.

Before inserting the insert mold 5 into the mold 2, it is heated using an electric furnace or the like to be preheated to 91% or higher than the melting point of the matrix metal. Whisker preform 1 to be set on this
6. It is effective to preheat the whisker preform, and for this purpose, it is operationally convenient to preheat the whisker preform while it is set in the insertion mold.

At this time, it is possible to control the degree of contraction of the composite material in the vertical direction by adjusting the preheating temperature of the insert mold and the preform 4. (2) The U volume fraction (Vr) can be adjusted appropriately by setting the

The inner mold 5 in which the whisker preform 1 is set is inserted into the mold 2 and placed on the top of the knife bunch 6 3, and the mold is heated through the impregnation process through the attached heating device. That is desirable. Subsequently, a molten matrix metal 3 is poured into the mold, and pressure is applied from above with a bran shear 4. Due to the pressurization, the molten metal 3 penetrates only from the upper surface of the whisker preform 1 in the direction of the arrow. After the matrix metal molten metal 3 is sufficiently impregnated into the entire Bran structure 4, it is solidified while the pressure is maintained.

[For production]

According to the manufacturing method, the whisker BRIFO 1 is set in a preheated insert mold and impregnated with molten metal, so that a normal molten state of the matrix metal can be maintained in the system throughout the impregnation process. Achieves sufficient heat retention゛4°
Ru. Moreover, since the molten matrix metal permeates unidirectionally from the top surface of the whisker preform, occluded gas components that are not present inside the preform structure are discharged out of the system from the bottom. It has the ability to effectively eliminate the imbalance of reaction components that tends to occur during use.

〔Example〕

Diameter 0.5~! , 5 μm 1 length 60-100 μw 1 density 3, l 8y/cm3, crystal form β type properties (=7
After dissolving the SiC whiskers well, they are dispersed in pure water, a wet whisker cake is formed by pressurization and filtration, and then heated and dried to form a cylindrical bluff with a diameter of 80 mm, a height of 130 cm, and a fiber volume ratio of 15%. Created A.-mu and created Noni.

” Two pairs of SiC whiskers with an inner diameter of 74 mm and an inner diameter of 80 mm
'llm1 Tool steel with an outer diameter of 120um and a height of 140+m (
It was inserted into an inner mold made of SK material and set, and then placed in an electric furnace and preheated to 700°C. Next, the preheated inner mold was inserted into a mold (inner diameter 12
0sR), and molten AC alloy (JIS standard 2014) at a temperature of 800°C was injected.

Subsequently, pressure was applied from above at a pressure of IO 00 kg/cm'' using a Brancier, and the pressurized state was maintained until the molten metal was completely solidified.

In the thus obtained SiC whisker-reinforced A12 composite material, the height of the composite portion shrank to 116zz, but no defects such as cracks or cracks in the structure were observed. The photograph in Figure 3 shows the metallographic structure of a cross section of a composite cast body that has been vertically split, solution-treated, and treated, so the leader line 7 indicates the composite part, and 8 indicates the composite part where the components are unevenly distributed. It is. From this situation, the composite, l(min) structure has homogeneous properties with no component segregation.
There was a f.

In addition, for this composite material, stagnation gas H was added using the Lansley method.
14: all + set, K-15. Icc/I
00g, the local deviation was slight.

For comparison, a SiC whisker-reinforced composite material was prepared using the same method as in the above example except that no interpolation mold was used. In this case, the whisker preform was placed in the center of the mold so that the elution penetrated in the direction of the arrow in FIG.

The composite material obtained in this comparative example was shrunk and deformed to a height of 125 m and a diameter of 75 m. FIG. 4 is a photograph of the metallographic structure of a cross section that has been insolubilized and treated with TG. An abnormal tissue portion 9 due to component segregation appeared in the center of the composite portion 7, and heterogeneity of the structure was observed. In addition, when the amount of gas contained in the composite material was measured, it was found that the central portion was 21. lcc/100g, outer circumference 8.3cc
/l OCJg and shows a higher value than the present invention example,
The results showed that the amount increased significantly in the center compared to the outer periphery.

〔Effect of the invention〕

According to the present invention, the maintenance of a normal molten metal state during the impregnation process during pressure casting and the effect of unidirectional penetration from the upper surface work synergistically, and a composite structure with homogeneous properties without any segregation abnormalities can be obtained. . Therefore, it has great value as a mass production technology for manufacturing high-performance fiber-reinforced metal composites with reinforced whiskers (4).

[Brief explanation of drawings]

FIG. 1 is a sectional view of an apparatus for explaining a conventional pressure casting method, and FIG. 2 is a sectional view of an apparatus for explaining a method of the present invention. FIG. 3 is a photograph of the metallographic structure of a processed cross section of a composite obtained by the method of the present invention, and FIG. 4 is a photograph of the metallographic structure of a processed cross section of the composite obtained by the conventional method. ! ...whisker preform, 2...mold, 3
...Elution of matrix metal, 4...Plunge γ-1
5...Insertion mold, 6...Lower punch, 7...m unit part, Yu I m 2nd x Certain 3 figure 4E

Claims (1)

[Claims] 1. A whisker preform is placed in a mold as a fiber skeleton, and a molten matrix metal is injected into the mold to form a composite by pressure casting, in which case the whisker preform is preheated. A method for manufacturing a fiber-reinforced metal composite material, which comprises setting it in an inserting mold and inserting it into the mold. 2. The method for manufacturing a fiber-reinforced metal composite material according to claim 1, wherein the whisker preform is set in an insertion mold, preheated, and then inserted into the mold.