JPS61209946A - Manufacture 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] [Field of Industrial Application] The present invention is applicable to the production of fiber-reinforced composite materials by infiltrating or impregnating matrix materials such as metals, alloys, or various plastics. The present invention relates to a method for producing a whisker preform to be used.

[Conventional technology]

An effective composite method for producing FRP or FRM using whiskers as a reinforcing material is a method of press-fitting a liquid matrix into a preform of a pre-shaped collection of whiskers and solidifying it. The tubular shape of the composite material obtained by this method is greatly influenced by the organizational structure of the whisker preform, which serves as the fibrous skeleton, and particularly by the degree of homogeneity thereof.

Furthermore, in order to mass-produce composite materials, it is an important condition to quickly and accurately form a whisker preform as an intermediate.

The applicant previously proposed the pressure filtration method (Japanese Patent Application No.
9-12049).

[Problem that the invention seeks to solve]

The pressure filtration method according to the prior art is a process in which the whisker product is dispersed in water or an organic solvent, this is filtered under gas pressure, and the remaining wet whisker cake is dried as it is or after being compressed to a predetermined density. Although the formed preform is an aggregate of whiskers alone, it exhibits ideal properties with a homogeneous integrated structure.

However, when using this method, agglomerated solid matter due to intertwining of whiskers may be mixed in, resulting in localized non-uniform portions in the preform structure.

Generally, the poorly dispersed nodule component contained in the whisker dispersion can be effectively removed by passing it through a sieve before filtration as described in JP-A-59-121196. It is not possible to capture fine solid matter of about 150 microns or secondary aggregates formed by intertwining of whiskers in the subsequent process.

The present invention aims to further improve the pressure filtration method by solving the above problems and effectively preventing the contamination of fine solids and secondary aggregates.

[Means for solving problems]

The structure of the present invention is that after the produced whiskers are dispersed in water or an organic solvent, they flow into a filtration device equipped with a sieve plate of 100 mesh or less and are filtered at high speed under gas pressure, and the resulting wet whisker cake is It is characterized by being dried as it is or compressed to a predetermined density.

Target whiskers are S r C, S 13N 4
Or a non-metallic single crystal such as graphite with a diameter of 0.
．． A reaction product with a length of 1 to 5.0 μm and a length of 10 to 500 μm serves as the starting material. These whisker products are usually
Since the short fibers have a cake-like structure in which they are intertwined in no direction, they are first loosened by an appropriate means, then placed in an organic solvent such as water, alcohol, acetone, or ether, and then placed in a mixer or a vortex stirring tank. Stir until the whiskers are evenly dispersed using a mixing device such as a . It is desirable to use water or an organic solvent as a dispersion medium in an amount 5 to 20 times the volume of the whisker in order to maintain smooth operation.

The dispersion then flows into a filtration device with a sieve plate and is filtered at high speed under gas pressure, and this operation is carried out using a device as exemplified in the figure.

In the figure, 1 is a lid portion equipped with a gas inflow orifice 2;
3 is a furnace tank, 4 is a sieve plate, 5 is a filter, and 6 is a bottom panel in which a large number of f-liquid flow holes 7 are installed.

The furnace vessel 3 can be designed in various shapes depending on the purpose, and in the case of a complicated shape, it can also have a split structure to facilitate the release of the molded preform.

The sieve plate 4 is interposed above the desired preform molding height, preferably at a position 10 to 25 mm above the height, but the sieve plate 4 is not limited to one stage and may be installed in multiple stages.

The opening of the sieve plate 4 needs to be 100 mesh or less, and if it is larger than this, it becomes difficult to capture fine solid matter of about 100 to 150 microns.

However, when the mesh exceeds 200, the filtration rate rapidly decreases. Therefore, the appropriate eye opening range is 100~
It is 200 meshes.

As the filter 5, ceramic furnace materials can be effectively used in addition to ordinary paper and furnace cloth. The joints between the furnace tank 3, the lid part 1, the filter 4, and the bottom plate part 6 are fixed in an airtight structure.

In the process, first fill the liquid 8, which is the same as the dispersion medium, up to just above the sieve plate 4, then flow the whisker dispersion liquid 9 into the furnace tank 3, and immediately connect the gas inlet orifice 2 to a compressor, gas cylinder, etc. Then, a gas such as air or nitrogen is pressurized into the upper sealed space S. By pressurizing the gas, the whisker dispersion 9 passes through the sieve plate 4 and is rapidly filtered, and the dispersion medium, water or organic solvent, is separated as a filtrate through the filtrate flow holes 7 within a very short time.

The wet whisker cake formed by filtration is dried as it is or after being compressed to a predetermined density considering the Vr value when it is made into a composite material.

Burn it.

[For production]

According to the present invention, since the whisker dispersion liquid is filtered under pressure while passing through a sieve plate of 100 mesh or less,
All forms of undispersed foreign matter, including fine solids on the order of 150 microns or secondarily generated whisker aggregates, are almost completely removed, and at the same time, the short time before the difference in sedimentation velocity occurs in the Stokes diameter distribution of whiskers. The filtration operation is completed.

In addition, if the same liquid as the dispersion medium is filled in advance to just above the sieve plate during filtration, it is possible to prevent the whiskers from settling unevenly before the gas is pressurized, and this has a better effect on homogenizing the preform structure. do.

〔Example〕

A generated S having a diameter of 0.5 to 1.5μ, a length of 50 to 100μ, a density of 3.189/cm', and a β-type crystal.
The iC whiskers were placed in a vortex-type stirring tank together with 10 times the amount of pure water, rotated and stirred for 10 seconds, and then passed through a 55 mesh sieve to obtain a whisker dispersion.

Using the filter device shown in the figure, which consists of a cylindrical furnace tank 3 (inner diameter 77 mm) with a 150-mesh sieve plate 4 interposed on the 110 mm upper part of the filter 5, pure water was poured to just above the sieve plate 4 with the bottom sealed. I put it in. The whisker dispersion liquid was introduced into the filtration device in this state, and air was immediately injected from the gas inlet orifice 2 via the compressor. The filtration process was continued while maintaining the air pressure in the upper closed space S at 5 to 9 cm'.

Through this pressure filtration, the whisker dispersion passed through a 150 mesh sieve plate, and the filtration was completed within 5 minutes.

The molded wet whisker cake was transferred to a constant temperature bath at 120°C and dried to obtain a cylindrical SiC whisker preform with a height of 98 mm.

The above SiC whisker preform was horizontally sliced into seven equal parts, and the values were measured for each disk specimen.

For comparison, a SiC whisker preform was formed under the same conditions using a filtration device without the sieve plate 4, and the vr value was measured in the same manner.

Table 1 shows a comparison of these results. In the table, No. indicates the order of each disk specimen cut from the top.

The results in Table 1 demonstrate that the whisker preform obtained by the present invention has a more improved structure homogeneity than the whisker preform obtained by the pressure filtration method before improvement (comparative example).

Note that the same results as in the above example can be obtained even when the present invention is applied using 5isN4 whiskers or graphite whiskers instead of SiC whiskers, and an organic solvent such as ethyl alcohol, acetone, or ether is used as a dispersion medium instead of pure water. I got it.

[Effects of the Invention] According to the present invention, all forms of foreign matter including fine solids and secondary agglomerates are effectively removed by the sieve separation action in the f-passing step, so regardless of the molded shape, A whisker preform with a highly homogeneous structure can be rapidly manufactured.

Therefore, the combination of a wide range of application fields including aircraft parts, automobile parts, and leisure and sports-related parts (
There are benefits that can greatly contribute to F'RP, FRM).

[Brief explanation of drawings]

The figure is a longitudinal sectional view illustrating a filtration device used in the present invention. l...Lid part, 2...Gas inflow orifice, 3...
Furnace tank, 4... Sieve plate, 5... Filter, 6... Bottom panel, 7... Liquid distribution hole, 8... Same liquid as dispersion medium, 9... Whisker dispersion liquid , S... Upper closed space.

Claims (1)

[Claims] After dispersing the generated whiskers in water or an organic solvent,
A composite material characterized by flowing into a filtration device with a sieve plate of 100 mesh or less and performing high-speed filtration under gas pressure, and drying the resulting wet whisker cake either as it is or by compressing it to a predetermined density. Manufacturing method of whisker preform for use.