JPS61143533A - Forming method of whisker preform for composite material - Google Patents

Abstract

PURPOSE:To form efficiently a titled preform having an intricate shape by introducing a whisker dispersion into a filter tank contg. a porous female mold having a desired shape and packing whiskers into the female mold by filtering operation. CONSTITUTION:The porous female mold 7 of a desired shape consisting of an upper die 8 and a lower die 9 is contained in the filter tank 1 and the liquid 11 prepd. by dispersing uniformly the whiskers (consisting of SiC, etc. and having about 0.1-5.0mu diameter and about 10-500mu length) is charged therein. Air is then forced into a hermetic space S via an orifice 5 of a cap part 6 and the liquid is filtered through a filter 4 and flow holes 2, by which the whiskers are packed into the female mold 7. The female mold 7 is then recovered from the filter tank 1 and the wet whisker molding is taken out of the tank and is dried, by which the molded whisker preform 12 is obtd. The preform 12 of approximately the same shape as the shape of the female mold is thus formed.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a complex fiber reinforced composite material used as a fibrous skeleton when manufacturing a fiber-reinforced composite material by infiltrating or impregnating matrix materials such as metals, alloys, or various plastics. The present invention relates to a method of forming a shaped whisker preform.

[Conventional technology]

As an effective means for manufacturing fiber-reinforced composite materials using whiskers as reinforcing materials, a method is known in which a whisker aggregate preform is placed in a predetermined mold and a liquid matrix material is press-fitted into the preform.

The composite material obtained by this method is extremely difficult to process and involves processing loss as a material, so it is desirable to form it into a shape that follows the final application part in advance at the stage of the whisker preform, which will become the fiber skeleton. .

The applicant has previously disclosed that as an effective means for producing a whisker preform for composite materials, the whisker product is dispersed in water or an organic solvent, and the resultant is filtered under normal pressure or gas pressure to remain. A method of drying a wet whisker cake as it is or after compressing it to a specified density (
JP 59-121196, JP 59-12049)
proposed. Although it is possible to form a benign whisker preform having an extremely homogeneous integrated structure even though it is an aggregate of whiskers alone, the obtained preform shape is limited to a relatively simple one. It was getting worse. Therefore, when a preform with a complex shape is required, the method used is to first form an integrated preform using the above method and then process it into the desired shape using cutting or other means. Due to its fragility, detailed machining requires considerable effort.

[Problem that the invention seeks to solve]

The present invention solves the above-mentioned problems and provides a method for extremely efficiently molding complex-shaped composite whisker preforms.

[Means for solving problems]

In the present invention, a whisker dispersion liquid is introduced into a filtration tank containing a porous female mold having a predetermined shape, a filtration operation is performed, and the porous female mold completely filled with whiskers is recovered from the filtration tank to form a wet whisker structure. The structural feature is to dry the shape.

The whiskers targeted by the present invention are SiC, Sj.

Non-metallic single crystal such as N4 or graphite with a diameter of 0.1~
A 5.0 μl, length lO~500 μ true aspect material is used as a starting material. The generated whiskers are placed in water or an organic solvent such as alcohol, acetone, or ether, and stirred using a stirring device such as a mixer or a vortex-type stirring tank until the whiskers are uniformly dispersed. When aggregates are mixed in the whiskers, it is effective to loosen them in advance by appropriate means in order to improve dispersibility.

The whisker dispersion thus prepared is passed through a sieve to remove poorly dispersed components, if necessary, and then filtered using a filtration device as illustrated in FIG.

The filtration tank 1 is composed of a bottom plate 3 in which T-liquid inflow and outflow 2 are perforated, a filter 4 made of filter paper, furnace cloth, ceramic furnace material, etc. is spread on the top surface of the bottom plate 3, and a lid part having an orifice 5 in the upper part. 6 is covered. 8 is a porous female mold and is housed at the bottom of the filtration tank l.

This porous female mold 8 is composed of a non-deformable mesh or perforated plate made of metal such as iron or copper or synthetic resin such as epoxy resin, phenol resin, polyethylene, etc., and is made by pressing, injection molding, etc. It is molded into a desired complex shape as illustrated in FIG. Structurally, holes with a diameter of 500μ1 or more are uniformly distributed on the outer surface with an area ratio of 10 to 90%, and, for example, as shown in FIG. It is desirable to design a split aperture mechanism that allows for The filtration operation is performed by flowing the whisker dispersion liquid 11 into the filtration tank 1, and then connecting the orifice 5 to a compressor or gas cylinder or the like, and pressurizing a gas such as air or nitrogen into the upper closed space S. The filtration proceeds rapidly as the gas is pressurized, and the dispersion medium, water or organic solvent, is separated as a filtrate in an extremely short time through the filtrate distributor 〇. During this process, the whiskers enter the female mold from all directions through the pores, and the over-operation continues until the female mold is completely filled with whiskers. When the filtration is completed, the female type 7
is embedded in the whisker residual cake in the filtration tank 1. Next, the porous female mold 7 is recovered from the filter tank 1, whiskers adhering to its surroundings are removed, and the wet whisker-constituting form is left in the female mold or taken out from the female mold and dried. When drying as a female mold, the mold is released as a molded preform after the drying process. The whisker preform 12 (FIG. 3) molded in this manner has the same shape as the female mold, and almost no dimensional shrinkage due to drying is observed.

〔Example〕

Density 3, 18 g/cm3. Diameter 0.5~1.
5μm.

β-5iC whiskers having a length of 50 to 100 μm were placed in a vortex-type stirring tank together with a 10-fold volume of water and uniformly dispersed by rotational stirring.

A porous female mold with a two-part opening structure was created by contacting a zinc iron wire mesh with an opening of 1 mm+ to the wooden mold of the rocker arm, and the entire surface was coated with acrylic resin to improve mold release. Using a filtration device having the structure shown in FIG. 1, the porous female mold described above was set in a filtration tank, and whisker-dispersed water was poured into the filtration tank. Air was forced into the upper sealed space and filtered while maintaining the air pressure at 5 kg/cm. After this filtration operation was performed until the female mold was filled with SiC whiskers, the female mold was removed from the filtration tank and the wet whiskers inside were removed. The constructed body was released from the mold.

The mold release was extremely smooth and no damage occurred to the details.

The wet whisker construct was dried in a 120° C. thermostat.

The SiC whisker preform thus obtained had the same shape in every detail as the original wooden mold, and exhibited homogeneous texture.

〔Effect of the invention〕

According to the present invention, it is possible to quickly and reproducibly mold a complex-shaped whisker preform for a composite material, which has been difficult to mold using conventional techniques.

Moreover, by housing the same type or multiple types of porous female molds in the f-container tank, multiple polymorphic whisker preforms can be molded at the same time, which is highly effective in mass production.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view illustrating a filtration device used in the present invention, and FIG. 2 is a perspective view illustrating a porous female mold. and the third
The figure is a perspective view of a whisker preform molded by the porous female mold of FIG. 2.

Claims (1)

[Claims] 1. A whisker dispersion liquid is poured into a filtration tank containing a porous female mold of a desired shape, a filtration operation is performed, and then the first porous female mold completely filled with whiskers is removed from the filtration tank. A method for forming a whisker preform for a composite material, the method comprising collecting and drying a wet whisker structure. 2. The method for molding a whisker preform for a composite material according to claim 1, wherein the porous female mold is constituted by a non-deformable mesh or perforated plate made of metal or synthetic resin, and has a dividing opening mechanism. .