JPS60204660A - Formation of whisker preform for composite material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Technical Field] The present invention provides a method for manufacturing a fiber-reinforced composite phase by infiltrating or impregnating matrix materials such as various plastics. The present invention relates to a method of forming a whisker preform used as a quality/n-grade.

[Technical background]

As an effective means for manufacturing fiber-reinforced composite materials using Tsudzu scars such as silicon carbide and silicon nitride as reinforcing materials,
A known method is to place a whisker aggregate preform in a mold, and to press and solidify a liquid matrix material into the preform. The properties of the composite material obtained by this method largely depend on the density and homogeneity of the structure of the whisker preform, which becomes the kasto skeleton. It is required to have sufficient non-deformability to

Applicants have previously disclosed that as an effective means of forming a composite whisker preform, the whisker product is dispersed in a water head or an organic solvent, and then subjected to Kfp under normal pressure or gas pressure.
proposed a method of drying the remaining wet whisker cake either as it is or after compressing it to a predetermined density (4? Application No. 57-226545, No. 59-1204).
9).

Although the whisker preforms according to the prior art are aggregates of single whiskers, they have an ideal form with extremely homogeneous and integrated tissue structure, but the formed preforms are less than 0.3t/σ8. In the case of a low-density structure, the non-deformability during compositing is not sufficiently maintained, resulting in plastic deformation which impairs the composite performance.

On the other hand, when manufacturing a fiber-reinforced metal composite phase by a high-pressure casting method, a method is known in which a fiber molded body that is mixed with the reinforcing phase is immersed in an inorganic binder solution to impregnate and fix the outer periphery (
4'jl-Kaisho 58-'34150). However, although this method is effective in maintaining non-deformability when the reinforcing material is long fibers, it is difficult to treat whisker preforms that are aggregates of extremely small short fibers. A situation occurs in which the preform itself deforms and collapses, and the application becomes a turning point.

[Structure of the Invention] In view of the above-mentioned circumstances, the present invention has succeeded in imparting effective non-deformability by applying and developing the whisker preforming/forming method according to the prior art. That is, in the structure of the present invention, generated whiskers are dispersed in an aqueous solution containing an inorganic binder, flowed into a filtration device, and filtered under atmospheric pressure with setake gas. It is characterized by being compressed to a high density and dried.

The target whiskers of the present invention are nonmetallic J11 crystals such as silicon carbide, silicon nitride, or graphite, and have a diameter of 0.
．． 1-5. A reaction product with a length of 10-50071 m is used as the starting material. When the whisker product exhibits a nodular, cake-like structure that intertwines with each other in no direction, it is disentangled in advance by an appropriate means before being used.

The above generated whiskers are placed in an aqueous solution containing an inorganic binder, and stirred using a stirring device such as a mixer or a vortex stirring tank until the whiskers are uniformly dispersed.

As the inorganic binder, materials such as water glass, colloidal silica, and alumina sol can be used, but because the solution becomes viscous or suspended, it is difficult to ensure uniform dispersion of whiskers and smooth interaction in the next filtration process. It is necessary to give sufficient consideration to the following. Suitable inorganic binder components are halonic acid and inorganic compounds belonging to the borates or aluminates of alkali metal scraps, such as sodium 119ate, sodium aluminate, potassium aluminate, etc., which, when combined, exhibit non-deformability. It has sufficient retention capacity and does not adversely affect composite performance, and does not generate viscosity that inhibits filtration operations in an aqueous solution state. The aqueous solution concentration of inorganic binder is generally 0.0
The effect of imparting non-deformability occurs from about 5 folds, but
．． If it exceeds zero, the residual ratio of the binder component increases, which is considered to be a factor that prevents circular penetration of the matrix. Therefore, it is desirable to set the concentration within the range of 0.5 to 5.0% by weight.

The whisker-dispersed aqueous solution is passed through a sieve to remove poorly dispersed components, if necessary, and then flows into the filtration device. The filtration device has a structure in which a filter made of VCF paper, P cloth, ceramic PI, etc. is inserted at the bottom of a container of the desired shape and size, and a gas such as air or nitrogen is injected under normal pressure or into the closed space above. Filter from the inside.

The wet whisker cake remaining on the top of the filter is compressed to a predetermined density in consideration of the Vf value when it is left or is made into a composite material in advance, and then dried.

The binder component functions to coat the surface of the whiskers through the dispersion and overtreatment process and to bond the whiskers together during the subsequent drying step to strengthen the formed preform.

[Effect of the invention] The whisker preform formed in this way is
It has an extremely homogeneous, strong, and non-deformable tissue structure in which whiskers are arranged in no direction, regardless of the shape of the excipient.

The whisker preform obtained in the present invention is made into a composite by infiltrating or impregnating it with IJ lux material selected from various types of fibers, alloys, or synthetic resins under pressure. However, due to the non-deformable force effect, plastic deformation due to compression can be kept to a minimum even in a low-density preform of 0.3 P 7 cm8 or less. Therefore, a very high performance FR
M, FRp) is guaranteed to be produced.

Practical TM Example 1 After a high-temperature reaction between the silicon source material and the next phase in a non-oxidizing ambient atmosphere in a temperature range of 1600° C., residual carbonaceous components were removed by combustion. Diameter 0.5-1.5 l thus obtained
A spongy cake (bulk density 0・Q 4
y/cm", average porosity 987 cm) was placed in a vortex type diode along with 10 times the volume of each f/Tt inorganic binder aqueous solution, and the mixture was rotated and stirred for 10 seconds to homogeneously disperse the whiskers.

The aqueous dispersion was passed through a cylindrical filter and the resulting wet whisker cake was dried at a temperature of 120°C. By the above process, a whisker preform with a diameter of 100 mm and a height of 125 mm was formed.

The density homogeneity of each of the formed whisker preforms was measured, and the results are shown in Table 1 in comparison with the type of inorganic binder used and the concentration of the aqueous solution. For comparison, an example (comparative example) K of a whisker preform formed under the same conditions without using an inorganic binder is also shown.

In addition, the result of density homogeneity was the bulk density of specimens cut from the upper and lower ends of the preform.

Table 1 The results in Table 1 show that all of the invention examples have excellent density homogeneity equivalent to that of the comparative examples.

Example 2 The whisker preform obtained in Example 1 was heated to 650°C.
The mold was preheated to 100°C, placed in a mold, and after pouring aluminum (lamb alloy) (AC8A) at a molten metal temperature of 800°C, a maximum pressure of 1000 kg/a' was applied using a bran shear. Next, the aluminum alloy was solidified while maintaining this pressurized state.

For the fiber-reinforced metal composited in this way, the degree of compression in the pressing direction of the whisker preform was measured. The results are shown in Table 1IK in correspondence with the original dimensions.

Table 11 The results in Table 11 show that although the whisker 7s7 ohm according to the present invention has a low bulk density of 0.16 Wlcr&, the compressive deformation when composited is only 1J·.

4V rr applicant Tokai Carbon Co., Ltd. agent Patent attorney Masaya Takahata

Claims (1)

[Claims] The whiskers produced in 1 are dispersed in an aqueous solution containing an inorganic binder, flowed into a filtration device, and filtered under normal pressure or gas pressure.
J. A method for forming a composite whisker preform, comprising compressing it to a predetermined density and drying it. 2. Free binder, 11 fluoric acid, alkaline gold.
A method for forming a composite whisker preform according to claim 1, wherein the whisker preform is an inorganic compound such as a filtrate or an aluminium salt.