JPH0685997B2 - Manufacturing method of short fiber reinforced metal composite - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to the production of a composite material of a metal matrix composite reinforced by ceramics whiskers such as oxides, carbides and nitrides, especially by a high pressure molten metal impregnation method. Concerning the law.

[Conventional technology]

As one of the methods for producing a composite material, there is a high pressure molten metal impregnation method. This method takes the following steps.

First, silicon carbide whiskers are mixed with water, an organic resin solution, or an aqueous solution to which inorganic salts are added to form a slurry. This is filled in a mold and compressed to obtain a molded body of a prescribed size (this is called a preform). The preform is then heated to the required temperature and loaded into the mold. Further, the molten metal is poured into a mold and the molten metal is impregnated into the preform by pressurizing the plunger to form a composite.

In the composite material obtained by the above method, whiskers are randomly dispersed. It is possible to use this,
In addition, by hot working, rolling, forging and other plastic working, round bar,
It is often used for plates, molds, forgings, etc. According to this type of plastic working, whiskers are randomly dispersed, but whiskers are oriented in the working direction along with the plastic flow of matrix metal. There is an effect that mechanical properties such as strength and elastic modulus are improved.

[Problems to be Solved by the Invention] Although there are satisfactory composite materials manufactured by the above-mentioned high pressure molten metal impregnation method, the preform may be cracked or deformed due to the pressure action of the molten metal during impregnation. It is considered that the main reason for this is that the molten metal is not evenly distributed around the entire circumference of the preform, so that the molten metal is offset and compounded.

When these composite materials are subjected to plastic working such as hot extrusion, rolling, and forging, it is judged that the composite material with cracks cannot be processed already. Directly contacts the die for machining, the difference in friction coefficient between the ceramics and the metal matrix is large, and the deformation rate becomes unbalanced, and the machined surface has rough skin and contains defects such as cracks. Further, when the whisker content is high, the composite material becomes more difficult to plastically work. Therefore, in order to improve the reliability of the composite material properties, it is necessary to devise a technique for forming the molten metal uniformly over the entire circumference of the preform during compounding.

[Means for Solving the Problems]

The present invention has been made to solve the above-mentioned problems, and the present invention is to insert a short fiber molding into a mold having a plurality of mountain projections on the inner peripheral surface thereof to form the mountain mold. A method for producing a short fiber reinforced metal composite material, comprising supporting the short fiber molded body by a protrusion so that the short fiber molded body is located at a central portion of the mold, and then press-fitting and supplying a molten metal into the mold. is there.

[Action]

According to the present invention, since the molten metal is uniformly pressed and pressed into the preform, defects such as deformation, cracking and deviation are eliminated. Furthermore, when applying a plastic working method such as hot extrusion to the short fiber reinforced metal composite material obtained by the method of the present invention, the composite material is covered with a ductile metal matrix, so that whiskers are directly processed. Since it does not contact the mold, it is possible to prevent defects such as cracks and rough skin.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to FIG. FIG. 1A is a plan view of the mold used in this example, and FIG. 1B is a sectional view taken along the line AA of FIG.

Silicon carbide whisker preform (volume ratio of whisker content)
30%) 1 is heated in an air furnace at 700 ° C., and then loaded into a mold 5 having a pressurizing mechanism by a plunger 3 and having a mountain projection 4. The aluminum alloy is melted at 750 ° C., and the molten metal 2 is poured into the mold 5. Immediately evacuated melt 2 and the mold 5 inside (including internal whisker pre foam) (1.33 × 14 ⁴ pa) was then, the melt 2 at plunger 3 pressing (800 kg / cm ²⁾ to into the preform 1 An impregnated composite ingot was produced.

The top surface (top side) and bottom surface (bottom side) of the composite material produced by the method of the present invention was polished and finished (# 600 emery paper) and confirmed to be No flaws are recognized.

Next, this ingot is isothermally heated to 400 ° C to 420 ° C,
A round bar was obtained by performing forward extrusion with an extrusion rate in the range of 10 to 30 mm and an extrusion ratio of 10: 1. The extrudability of the ingot covered uniformly is
We were able to obtain a good extruded product with no tearing or rough skin.

On the other hand, regarding the composite material manufactured by the conventional method using the mold 5'as shown in FIG. 2, in the same inspection as above, as shown in the figure, the preform 1 is compounded in a biased state. , Top surface of the obtained composite material (top side)
Crack 6 was found in. 2A is a plan view of a conventional mold 5 ', and FIG. 2B is a sectional view taken along the line BB of FIG. 1A. The same parts as those in FIG. 1 are designated by the same reference numerals. .

〔The invention's effect〕

According to the present invention, it is possible to prevent defects such as cracking, deformation and offset for producing a composite material by the molten metal impregnation method, and the obtained composite material is also applicable to plastic working such as hot extrusion. The effect of having good lubricity was recognized.

[Brief description of drawings]

FIG. 1 is a schematic view of a mold used in one embodiment of the present invention.
(A) is a plan view thereof, (b) is a sectional view taken along the line AA of (a), and FIG. 2 is a schematic view of a mold used in the conventional method.
Is a plan view thereof, and (b) is a BB sectional view of (a). In the drawing, 1; silicon carbide whisker preform, 2; molten aluminum alloy, 3; plunger, 4; chevron protrusion, 5,
5 ': mold, 6: crack.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Bibliographic references Sho 60-146559 (JP, U)

Claims (1)

[Claims] 1. A short fiber molding is inserted into a mold having a plurality of mountain projections on its inner peripheral surface, and the short fiber molding is positioned at the center of the mold by the mountain projection. The method for producing a short fiber-reinforced metal composite material, comprising: pressurizingly supplying the molten metal into the mold after supporting the molten metal.