JPS61113738A - Low density whisker forming body for composite material, and its production - Google Patents

Abstract

PURPOSE:To produce low density whisker forming body for a homogeneous composite material provided with a non-destructive deforming property by dispersing an SiC whisker and an inorganic short fiber into a solvent with a specified ratio and thereafter, filtrating it at a high speed and drying an obtained wet cake. CONSTITUTION:The SiC whisker consisting of an SiC needle-shaped single crystal of about 0.1-2.0mum diameter and about 30-200 aspect ratio, and an inorganic short fiber of 2.0-4.2g/cm<2> Al2O3, etc. and about 50mum length are added into an organic solvent such as water or alcohol, in the ratio of 0.1-2 volume ratio, stirred and dispersed uniformly. Subsequently, the obtained dispersed solution is filtrated at a high speed by using a filtrating device and pressing in a gaseous body such as air. The obtained wet whisker cake is dried, and a low density whisker forming body for the composite material provided with a homegeneous organization structure and a non-destructive deforming property for resisting an external force, and with <=10% volume rate Vf, is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention provides a method for manufacturing fiber-reinforced composite materials by soaking or impregnating matrix materials such as metals, alloys, or various plastics. SiC used as
This article relates to a whisker low-density compact and its manufacturing method.

[Conventional technology]

FRP or FR using SiC whiskers as reinforcement material
As an effective composite means for manufacturing M, a method is known in which a liquid matrix is press-fitted into a pre-formed whisker aggregate and solidified. The properties of the composite material obtained by this method largely depend on the properties of the whisker molded body that forms the fibrous skeleton, and it is especially important to impart density and homogeneity of the microstructure to the molded body, as well as non-destructive deformability that can withstand external forces. It is an important property factor in manufacturing performance composite materials.

The applicant previously proposed a method for forming a whisker preform for composite materials by dispersing the whisker product in water or an organic solvent, filtering it under normal pressure or gas pressure, and dispersing the remaining wet whisker cake as it is or in a predetermined form. Developed a method of drying after compressing to a high density
196, patent application 1982-+2049). Since the whisker reform made by the prior art is an aggregate of individual whiskers, it has an extremely homogeneous integrated structure, which is an ideal property; In the case of a low-density structure of less than 10%, the non-destructive deformability of the molded product cannot be sufficiently maintained, resulting in breakage during handling or plastic deformation during the compound process, resulting in poor quality. There were drawbacks such as deterioration of the

A method for imparting non-destructive deformability to a molded body is to strengthen the bond using a binder. However, the use of a binder has many problems, as it may impede smooth impregnation of the matrix material and wettability with the skeletal fibers, and may also cause unfavorable chemical reactions with the matrix material.

[Problem that the invention seeks to solve]

The present invention solves the problems of the prior art and provides a low-density SiC whisker molded body for composite materials that has sufficient non-destructive deformability without using a binder component, and a method for producing the same.

[Means for solving the problems] The SiC whisker molded body provided by the present invention is made of S
It has a low-density structure with a volume fraction (Vf) of 0% or less as an iC whisker, and is made of a structure in which SiC whiskers are mixed with inorganic short fibers.

The SiC whisker serving as a reinforcing material has a diameter of 0.1 to 2.
A material made of SiC needle-shaped single crystal with 0 micron particles and an aspect ratio of 30 to 200 is used.

The inorganic short fiber is a material that functions to provide formability and non-destructive deformability to a dense and dense structure with SiC whiskers.
The fiber length used is at least longer than the SiC whisker. For example, A12t's.

C, B, and SiC L" are targeted for chopped fibers with a length of 500 uz or more, which are obtained by chopping ANtOs' 840w long fibers, but these common short fibers inhibit the wettability with the matrix material. Si should not be used at the molding stage.
It is necessary to have density characteristics that allow homogeneous dispersion and mixing with C whiskers.

The staple fiber that best meets these requirements is A Q Os
and short fibers of SiC.

By aggregating the above SiC whiskers and inorganic short fibers, the volume fraction (Vf) of the SiC whiskers is 1.
In order to form a low-density compact of 0% or less, the following manufacturing method is used.

SiC whiskers and short inorganic fibers are immersed in water or a growth solvent such as alcohol, acetone or ether and stirred using a mixing device such as a mixer or vortex stirring tank until uniformly dispersed.

When aggregates are mixed in the SiC whiskers, it is effective to loosen them in advance by appropriate means in order to improve the dispersibility.

On the other hand, inorganic short fibers have a density of 2,0-4,29/c
m'.

It is desirable to select from a property range of 500 to 5000 micro degrees in length. In particular, the density range of 20 to 4.29/cm'' is an important requirement for forming a homogeneous mixed structure, and when the density of the common inorganic short fibers is less than 20 g/cm' or more than 4.2 g/cm' Due to the large difference in the density of SiC whiskers (3,1897 cm"), differences in the degree of floating and sedimentation occur in the above dispersion process or the next filtration process, resulting in inhibiting uniform mixing. .

The ratio of SiC whiskers and inorganic short fibers to be dispersed in water or a growing solvent is set in advance at a volume ratio of 1:o, from a range of 1 to 2, taking into consideration the desired Vf value when used as a composite material.
The volume ratio of inorganic short fibers to SiC whiskers is 0.
．． When it is less than 1, the SiC whisker volume fraction (Vf) is 10
It becomes difficult to form a molded body with a low density of less than 2%, and if this ratio exceeds 2, the reinforcing performance as a SiC whisker will not be exhibited.

This dispersion solution is passed through a sieve to remove poorly dispersed components, if necessary, and then flows into a filtration device. The filtration device has a structure in which a filter such as filter paper, filter cloth, or ceramic filter media is inserted at the bottom of a container with the desired dimensions.
High-speed filtration is performed using a method such as pressurizing a gas such as air or nitrogen into the upper closed space.

The wet whisker molded body remaining on the top of the filter is then subjected to a drying process to remove the solvent component. The molded article produced in this manner has an extremely low-density structure in which the volume fraction of SiC whiskers (■'') is 10% or less.

[For production]

The molded article according to the present invention has a SiC whisker volume ratio (v r) of 10% due to the shaping effect of the mixed inorganic short fibers.
Since it has the following loose and dense structure, it has sufficient non-destructive deformability. Furthermore, since the inorganic short fibers used have a density similar to that of SiC whiskers, mutual dispersion will not deteriorate during the manufacturing process. Therefore, a molded article with a homogeneous structure without density unevenness can always be obtained.

[Example I]

Density 3, 18g/c1m3. straight 10.5~1.5
μ shoulder.

Using β-5iC whiskers with a length of 50 to 100 μl and AQ fibers with a density of 3.4 g/c@” as inorganic short fibers, directly scratched 2 to 4 μl, and a length of 1000 to 4000 μl, the volume ratio is 1:0. .25.1・1.l: 1.5
The SiC whiskers and short fibers were placed in a vortex type stirring tank together with pure water at various ratios, and the SiC whiskers and short fibers were homogeneously dispersed by rotational stirring.

The aqueous dispersion solution was poured into a cylindrical filter and filtered, and the resulting wet whisker cake was dried at a temperature of 120°C. In this way, a molded body for composite material having a diameter of 70 tx and a height of 805,111 mm was formed.

The density homogeneity of each molded body formed is taken as the Vf (%) measurement value of specimens cut from the upper and lower ends, and the results are compared with the blended volume ratio of SiC whiskers and AQ20° short fibers, and are shown in Table I. It was shown to.

For comparison, a molded body similarly formed using only the SiC whiskers described above is also listed (comparative example).

The results in Table 1 show that all the low-density whisker molded bodies according to the examples of the present invention have density homogeneity equivalent to that of the comparative examples, and A
Q, 03 SiC whisker Vrl according to short fiber blending ratio
It is recognized that less than alO% can be obtained.

[Example 2] Each of the whisker molded bodies formed in Example 1 was preheated to 650°C, placed in a mold, and pure aluminum (1060) with a molten metal temperature of 750°C was poured into the mold. A pressure of cm' was applied. Then, matrix AQ was solidified while maintaining this pressurized state.

Regarding the FRM composited in this way, the degree of compressive deformation in the pressurizing direction of the molded body, the fracture situation, and the reinforcement performance (
The tensile strength) was measured and observed. The results are summarized in Table ■.

The results in Table ① show that the whisker molded body according to the present invention is SiC.
Although the volume fraction (Vf) of the whiskers is at a low level of 10% or less, there is no destruction during compounding and the degree of deformation is small. Moreover, the tensile strength of FRM is S due to the hybrid effect of Aσ20□ short fibers
The increase is greater than when using a molded article containing only iC whiskers. This situation is shown in Run No. 4 from Run No.
This can be confirmed by the fact that I has improved strength performance.

〔Effect of the invention〕

The whisker molded article for composite materials provided by the present invention can be used with SiC whiskers and (il) irrespective of the shaping shape.
[ffl ff It has a homogeneous structure in which short fibers are intertwined in no direction, and has non-destructive deformability that can sufficiently withstand handling or heat-pressure conditions during +U association. Therefore, SiC whisker volume fraction (Vf) 1 that does not contain a binoder component
Even though it is a low-density whisker molded product with less than 0%, the composite progresses smoothly without damage or plastic deformation due to matrix press-fitting, and this combined with the hybrid effect due to the common use of inorganic short fibers results in a consistently high-performance composite. Material (FR
P.

FRM). In particular, the whisker molded body for composite materials of the present invention is suitable for forming FRM composites using molten metal matrix, which requires severe heat-pressing conditions, and the obtained FRM billet is processed to form a composite material by hot forging, extrusion, rolling, etc. - It can be formed into products for a wide range of applications, including aircraft parts such as blades, automobile parts such as connecting rods, cam levers, pistons, and gears, and sports-related parts such as inserts for tennis clubs and golf clubs.

Patent applicant: Tokai Carbon Co., Ltd. Agent: Patent Attorney Masaya Takahata, i

Claims (1)

[Scope of Claims] 1. A low-density whisker molded product for a composite material, in which SiC whiskers are mixed with inorganic short fibers and the volume fraction (Vf) of the SiC whiskers is 10% or less. 2. SiC whiskers and density 2.0-4.2g/cm^
3 inorganic short fibers are dispersed in water or an organic solvent at a volume ratio of 1.0.1 to 2, followed by high-speed filtration, and the resulting wet whisker cake is dried. A method for producing a low-density whisker molded body for composite materials having a volume fraction (Vf) of 10% or less.