非水解溶胶-凝胶法结合碳热还原法制备β-SiC粉体

摘要

为了用较为简便的方法以及廉价原料制备出β-SiC粉体,采用非水解溶胶-凝胶法,以分析纯的四氯化硅(SiCl4)、正硅酸四乙酯(TEOS)为原料,加入催化剂无水氯化铁(FeCl3)制备出溶胶,然后转移至反应釜中能制备出SiO2干凝胶.分别以SiO2干凝胶或石英砂为硅源,与炭黑混合,SiO2干凝胶或石英砂与炭黑的质量比为3∶2,采用碳热还原技术,在氩气气氛中于1 500℃保温2.5h制备出SiC粉体.采用FTIR、XRD和SEM测试方法研究凝胶过程以及碳热还原产物.结果表明:原料TEOS经过非水解缩合反应制备出的SiO2干凝胶活性较高,而后用其制备出物相较为纯净的SiC粉体,其晶粒尺寸细小,粒径均匀,粉体表面存在少量的短晶须.%In order to prepare β-SiC powder using simple methods and cheap materials,the silica xerogel was firstly prepared by non-hydrolytic sol-gel method using analytically pure silicon tetrachloride (SiCl4) and tetraethyl orthosilioate (TEOS) as raw materials,and adding anhydrous ferric chloride (FeCl3) as the catalyst.Then the SiO2 xerogel or quartz sand was mixed with carbon black repectively according to 3∶2 of the mass ratio of silica xerogel or quartz sand to carbon black and firing at 1 500 ℃ for 2.5 h in argon atmosphere to prepare silicon carbide powder by carbothermal reduction.The gel process and carbothermal reduction products were studied by FTIR,XRD and SEM.The results show that the SiO2 xerogel prepared from TEOS through non-hydrolytic condensation reaction has high reactivity;when the SiO2 xerogel is used as the silica source,pure SiC powders with uniform and small particle size are obtained and there are a small amount of short whiskers in the powder surface.