JPS6360165A - Manufacture of fiber reinforced ceramics - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a method for producing a high-toughness ceramic material, and more specifically, when producing a fiber-reinforced ceramic material,
It is characterized by the ability to obtain ceramic materials with even higher toughness by processing using the sol-gel method.

(Prior art) Fine ceramic materials represented by S13N4 (silicon nitride) and SiC (silicon carbide) have high bonding strength and excellent heat resistance, so they are used as strength materials or wear-resistant materials used in high-temperature environments. Applications are expected, and some of them have already begun to be used in engine turbo rotors, etc. but.

Ceramics are brittle materials, and in order to increase their reliability, it is necessary to overcome their brittleness. In other words, high toughness is a characteristic that has always been sought after in ceramic materials.

(Problem to be solved by the invention) Recently, various methods have been devised for the purpose of increasing the toughness of this ceramic material, and one of the methods that has attracted attention is the composite of ceramic fibers or whiskers and a matrix. ing. In the case of these composites, their strength characteristics and fracture mechanisms are very complex and cannot be generalized, but in general, the strength of ceramic materials is
It is greatly influenced by the density of the material itself, and can be improved by reducing the size and number of defective pores existing inside the material. In order to achieve this densification in a composite material, the first condition is uniform dispersion of the fibers or whiskers and the matrix, but when conventionally mixed with fibers or whiskers, the fibers are entangled with each other and the inside of the matrix is dispersed. It is difficult to uniformly disperse the matrix, and it is very difficult to obtain a sintered body that is dense and homogeneous in roughness. Furthermore, when it is desired to control the interface state between fibers or whiskers and the matrix, conventional methods may be difficult, and as a result, it is currently difficult to obtain a densified sintered body of the above-mentioned composite. .

The present inventors have repeatedly made improvements to solve the above problems, and have discovered that a homogeneous densified sintered body of the above composite material can be obtained by using the sol-gel method. 6 [Structure of the Invention] (Means for Solving the Problems) The present inventors have , SiC fibers or whiskers are coated with a hydrolysis product of silicon alkoxide and carbon mixture, and Si is coated on the fibers or whiskers by heating and reacting in a nitrogen atmosphere.
It has been found that the above objective can be achieved by precipitating 3N4 and sintering them. That is, the method of the present invention uses silicon ethoxide as silicon alkoxide,
Mix carbon with silicon propoxide, etc. At the edge of the frame, Si produced by hydrolysis of silicon alphoxide
The amount of n is preferably 0.4 to 1 part by weight per 18 parts by weight of carbon. SiC fibers or whiskers are immersed in this mixed solution, hydrolyzed in an acidic or alkaline solution, and then dried. In some cases, the fiber or whisker surface may be uniformly coated with 510. and carbon is coated. These are nitrided and reduced in a nitrogen stream, and S is uniformly distributed on the SiC fiber or whisker surface.
i3N is precipitated. Furthermore, if necessary, by adding an alkoxide or the like as a sintering aid, these can also be coated uniformly. It has been found that by forming and sintering these, a densified sintered body in which fibers or whiskers are uniformly dispersed in the matrix can be obtained, and the toughness can be improved. Further, the carbon is not limited to carbon powder, and a carbon compound that produces carbon upon firing may be mixed.

[Embodiments of the invention]

(Example) 100 g of silicon tetraethoxide and 4.5 g of yttrium ethoxide were placed in a beaker. , ethanol 30-, carbon source 20H, Sj, and 10 g of C fiber were added and kept at 30° C. while stirring. The pH was maintained at approximately 1 using I(C1!).

Next, 22g of distilled water was gradually added to carry out a hydrolysis reaction for 70 hours.After one reaction, these were taken out from the beaker and
After drying at 10°C, it is nitrided and reduced at 1450°C for 10 hours in a nitrogen atmosphere. After molding these, 1780℃-400
HOT-PIIES under kg/cd -1 hour condition
Using the 5ENB method, the fracture toughness value [Ie
(MN-m-'')) was measured and found to be 10.1.

Conventional S13 N493 K T AQ2032 g
35 g of each powder were mixed in butanol using a ball mill.

After dry molding, when the fracture toughness value (KIc) of the product was measured using the 5ENB method under the conditions of 1780℃-400℃/-11 hours, the value was about 7 to 8. .

〔Effect of the invention〕

According to the present invention, a highly tough ceramic material with excellent mechanical properties can be provided.

Agent: Patent Attorney Noriyuki Chika Same as Hisao Takehanakawa

Claims (1)

[Claims] When producing Si_3N_4 (matrix)-SiC (fiber or whisker) based fiber-reinforced ceramics, hydrolysis of alkoxides containing silicon (
Sol-gel method) A fiber-reinforced type characterized by coating SiC fibers or whiskers with a mixture of the product and carbon and heating them in a nitrogen atmosphere to precipitate matrix components on the surface of the SiC fibers or whiskers. Ceramics manufacturing method.