温度和催化剂添加量对催化合成SiC粉体的影响

Effects of Temperature and Catalyst Content on Synthesis of SiC Powder via Catalytic Method

采用Si粉、酚醛树脂和硝酸铁为原料,通过简单的催化碳化工艺在氩气下合成SiC粉体。研究了热处理温度和硝酸铁添加量对合成SiC形貌和生成量的影响,并揭示了SiC的形成机理。结果表明,热处理温度为1450℃,硝酸铁添加量为5%时,可以制备结晶度和生成量较高的SiC粉体;不添加硝酸铁的试样中,SiC晶须以直线形和表面粗糙的絮状形貌存在;添加硝酸铁促进了SiC晶须的生成,晶须以絮状形貌为主,其直径尺寸减小,且表面变得光滑;热处理温度低于1410℃(Si熔点温度),不添加催化剂和添加催化剂的样品中晶须分别遵循气-固和气-液-固生长机制,而热处理温度高于1410℃时,晶须遵循气-液-固生长机制。

Si powder,phenolic resin and ferric nitrate were used as raw materials to synthesize SiC powder under Ar gas through a simple catalytic carbonization process.The effects of heat treatment temperature and ferric nitrate content on the morphology and yield of synthesized SiC were investigated,and the formation mechanism of SiC was revealed.The results showed that when the heat treatment temperature was 1450℃and the addition of ferric nitrate was 5%,SiC powders with higher crystallinity and content were prepared;In the samples without adding ferric nitrate,the SiC whiskers existed in the shape of linear morphology and flocculent morphology with rough surface.The addition of ferric nitrate promoted the formation of SiC whiskers,their morphologies were mainly flocculent,the diameter decreased and the surface became smooth.When the temperature was lower than 1410℃(the melting point temperature of Si),the whiskers in the samples without catalyst and with catalyst followed the gas-solid and gas-liquid-solid growth mechanisms,respectively;When the temperature was higher than 1410℃,the whiskers followed the gas-liquid-solid growth mechanism.