SYNTHESIS AND MECHANISM OF SiC-ZrC COMPOSITE POWDERS BY CARBOTHERMAL REDUCTION METHOD

Abstract

SiC-ZrC composite powders were synthesized by carbothermal reduction method using starch as carbon source, zirconium dioxide as zirconium source, and silica sol as silicon source. The effects of reaction temperature on the phase composition and microstructure of SiC-ZrC composite powders were investigated. The reaction process was thermodynamically analyzed and calculated, and the synthesis mechanism of SiC-ZrC composite powder was analyzed. The synthesized powder samples were characterized and analyzed by X-ray diffraction, scanning electron microscopy, and other testing methods. Results show that the optimum reaction condition for the synthesis of SiC-ZrC composite powders is at 1550 ̊C-1600 ̊C for 1.5 h. High temperature and low pressure are beneficial in conducting the synthesis reaction. The SiC-ZrC composite powders synthesized by calcining at 1550 ̊C and holding for 1.5 h are mainly composed of a certain amount of whiskers, spherical particles, floc particles, and other structures. Moreover, their grain size is small (100-200 nm). The powder samples synthesized at 1600 ̊C produced a larger number of whiskers. The length of the whiskers was mostly 10 μm, the arrangement was complex and irregular, and a diverse microstructure was formed.

Keywords

• reaction temperature
• sic-zrc
• carbothermal reduction method
• synthesis
• composite powders
• mechanism