Method for preparing self-toughening silicon nitride ceramics

Abstract

The invention provides a method for preparing self-toughening silicon nitride ceramics, and the method comprises the following steps that first a silicon nitride foam ceramic billet is prepared, then sintered to prepare a silicon nitride crystal whisker skeleton body, and finally a silicon nitride organic precursor is dipped, cracked and made into ceramics and the self-toughening silicon nitride ceramics is prepared. According to the method for preparing self-toughening silicon nitride ceramics, the silicon nitride ceramic foam body is obtained by directly foaming; then the silicon nitride ceramic foam body is sintered; a long column-shaped beta-silicon nitride crystal bar is fully grown through the special structure of a large number of pore spaces of the ceramic foam when in sintering; the grown long column-shaped beta-silicon nitride (Si3N4) crystal bar is nearly fully filled in each foam pore in the silicon nitride foam ceramic body; the average slenderness ratio of the beta-Si3N4 crystal bar is 20, and the maximum slenderness ratio can reach about 30; and the silicon nitride crystal whisker skeleton body which is obtained by sintering the silicon nitride foam ceramic billet is dipped and cracked to obtain the self-toughening silicon nitride ceramics, and the toughening effect is good.

Description

technical field [0001] The invention relates to a method for preparing self-toughened silicon nitride ceramics, belonging to the technical field of silicon nitride ceramics. Background technique [0002] Silicon nitride (Si 3 N 4 ) Ceramic is a high-temperature structural ceramic with excellent performance developed in the 1950s. It has high high-temperature strength, high hardness (Mohs hardness is 9), low high-temperature creep, low thermal conductivity, small thermal expansion coefficient, and good thermal shock resistance. , stable chemical performance, corrosion resistance and other characteristics. Taking advantage of the above properties, silicon nitride, as a high-temperature structural ceramic, has been applied to cutting tools, wear-resistant parts, automobile bearings, piston tops, cylinder liners, precision machinery and aircraft bearings, etc. In the end parts, there are also broad application prospects. [0003] However, since silicon nitride ceramics is a ...

AI Technical Summary

Problems solved by technology

By the end of the 1980s, many researchers controlled the β-Si 3 N 4 Self-toughening Si with excellent mechanical properties due to small grain size 3 N 4 Materials, Luo Xuetao and others have done a lot of research in this area, studying the growth of silicon nitride whiskers in homogeneous or dense silicon nitride, and the β-Si in the prepared silicon nitride ceramics 3 N 4 The aspect ratio is about 10, and the longest is no more than 15. The obtained grain has a small aspect ratio and the toughening effect is not good.

Images