TEOS的溶胶-凝胶行为对合成碳化硅晶须的影响

Effect of TEOS sol-gel behavior on synthesis of SiC whiskers

为了制备直晶率高，光洁度好，长径比均匀，强度大的碳化硅晶须，以正硅酸乙酯（TEOS）和蔗糖为原料，无水乙醇为溶剂，pH为1～2的HCl为催化剂，采用溶胶-凝胶法制备碳化硅晶须，重点考察了TEOS溶胶凝胶行为即HCl的引入方式（直接滴加法和水溶液法）、水解温度（20、40和60℃）、搅拌时间（15、30、45和60min）对合成碳化硅晶须的影响。结果表明：pH为1～2的盐酸以水溶液的形式加入正硅酸乙酯中，在40℃恒温水浴锅中搅拌30min，可使正硅酸乙酯充分水解缩聚；在氩气气氛下1500oC煅烧1h制得的β—SiCw量最多，表面光洁，直径在60～100nm，直晶率高，且长径比均匀。

This work aimed at preparing silicon carbide crystal whiskers with high straight crystal rate,good smoothness,uniform length to diameter ratio, and high strength. Tetraethoxysilane （TEOS） and sucrose were used as starting materials,absolute ethyl alcohol as the solvent,and HCI with pH value of ] -2 as the catalyzer. The effect of the TEOS sol - gel behavior namely the introduction method of HCi （ direct adding and aqua-solution method）, hydrolysis temperature （20,40, and 60℃）, stirring time （ 15,30,45, and 60 min） on the synthesized whiskers was investigated. The results show that adding HCI solution into tet-raethoxysilane and stirring for 30 min at a 40 ℃ water bath can make the tetraethoxysilane hydrolyze and condense completely. The specimen calcined at 1500℃ for 1 h in Ar atmosphere has the highest β-SiCw content and the obtained fibers have smooth surface, diameter of 60 - 100 nm, high straight crystal rate, and uniform length to diameter ratio.