JPS60231467A - Composite ceramics - 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 relates to composite ceramics that can be used in various fields such as solid lubricants, molten metal holding materials, bearings, and others.

(Prior art) Hexagonal boron nitride heat exchangers have good lubricity and mold release properties, so they are used as solid lubricants, molten metal holding materials, etc. However, boron nitride molded bodies are It has poor compressive strength and bending strength, and easily breaks when stress is applied. In addition, the wear resistance is low, and the wear and tear is significant when used as a lubricant. The object of the present invention is to obtain a ceramic material with improved strength and wear resistance without impairing mold releasability.

(Means for Solving the Problems) The present invention improves strength and wear resistance by mixing short ceramic fibers into a hexagonal nitrided boron heat exchanger. If short ceramic fibers are used as a reinforcing material for hexagonal nitrided cavities, the short ceramic fibers themselves exhibit good lubricity, so nitriding does not impair the lubricity and mold release properties of boron. According to the compound rule, nitriding improves the strength of the borax heat exchanger and also improves its wear resistance.

Note that the above-mentioned short fibers are whiskers or continuous fibers cut into pieces, and the length is approximately several tens of micrometers to several micrometers.

The fiber-reinforced hexagonal boron nitride sintering body according to the present invention is prepared by adding 5 to 50% by weight of a short material such as Al2O3, Sic, Si3N4, etc. After adding fibers alone or in combination, the amount of ceramic short fibers is 5 to 60%, which is press-molded and sintered by hot pressing or hot isostatic pressing.
The weight percentage is based on the fact that at least 5 layers of steel are required to improve strength and abrasion resistance, and additional 7Jll
There is no particular limit to the upper limit of the amount, but due to manufacturing technology, it is
The limit is heavy electric power.

(Function) As shown in Table 1, the ceramic fibers contained in the hexagonal nitride boron body have high strength and elastic modulus, and randomly oriented short fibers are applicable to unidirectionally oriented long fibers. Composite agent [σ. (Strength of composite material) = σf'
Vf+σ, ・vm, where σf: strength of fiber, vf: volume fraction of fiber, σm: strength of base material, vm: volume fraction of base material]
Gives strength of about 100.

Table 1 Furthermore, since ceramic short fibers are in the form of fibers rather than grains, they are difficult to fall off even if they appear on the surface, and even after the base material, boron nitride, is worn out, some of them remain in the wired state. remain. These short fibers are elastically deformed by contact with the mating material, exhibiting lubricity, and reducing the contact pressure with the base material, boron nitride, thereby reducing the amount of wear on the base material.

(Example) Hexagonal nitriding consists of only boron, plus Al, O, SiC.

Regarding the composite material obtained by adding short fibers of Si3N4 in the proportions shown in Table 2, and adding B, 034% by weight, and 2% by weight of CaO as binders, the material was really pressed at 1800°C x 3ookg/horse gas. The friction coefficient was measured and the wear loss was measured using a Suzuki type wear tester.This result was used in the second test.
Shown in the table.

Table 2 *Continuous fiber cut into 2 to 5 pieces Ji indicates the weight person.

As is clear from Table 2, the short fiber content is 5
If the nitriding is less than t%, the amount of wear of boron is large;
It can be seen that the amount of wear decreases when 5% by weight or more is added.
It is also clear that there is little or no change in the coefficient of friction for any of the samples.

Among the sub-agents: 1) Akira Sub-agent Ryo Hagi Hara -

Claims (1)

[Claims] Hexagonal nitride is a composite ceramic made by adding 5% by weight or more of short ceramic fibers to a boron molded body.