Method for preparing equiaxed alpha-phase silicon nitride powder

Abstract

The invention discloses a method for preparing equiaxed alpha-phase silicon nitride powder. The method comprises the steps that with silicon tetrachloride and liquid ammonia as raw materials, a silicon imine solid is synthesized under a liquid phase condition, and then the silicon imine solid is thermally decomposed to obtain amorphous silicon nitride; the amorphous silicon nitride and auxiliary additives are treated by a ball milling process for full and uniform mixing; the obtained mixture is put into a graphite or boron nitride crucible, crystallization is carried out for 0-48 hours in an atmosphere sintering furnace under a certain atmosphere condition, and then the equiaxed high-alpha-phase silicon nitride powder with few impurities is obtained. The preparation process of the siliconnitride powder is short in period, the particle morphology of silicon nitride is easy to control, and large-scale industrial production is facilitated.

Description

technical field

[0001] The invention relates to a method for preparing equiaxed α-phase silicon nitride powder, which belongs to the field of inorganic non-metallic materials. Background technique

[0002] Silicon nitride ceramics have the characteristics of high temperature resistance, good chemical stability, high mechanical strength, and self-lubrication. They are widely used in cutting ball bearings and other wear-resistant parts, high-temperature ceramic bearings, and high-temperature resistant parts for automobile engines. Compared with aluminum nitride ceramics and alumina ceramics, high thermal conductivity silicon nitride ceramics have both high thermal conductivity and high mechanical strength. In addition, during the demoulding process of polysilicon, the α-phase silicon nitride powder does not react with molten silicon, which is suitable for the requirements of crucible coating in the process of purifying polysilicon. High-quality silicon nitride raw material po...

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