以AlCl3·6H2O和TEOS(Tetraethyl Orthosilicate)为主要原料,分别用NH4OH和(NH4)2CO3作为沉淀剂,采用Sol-Gel法结合真空冷冻干燥技术制备出两种Al2O3-SiO2气凝胶,使用TG-DSC、XRD和BET等技术分析了两种气凝胶在热处理过程中的变化.结果表明:用NH4OH作沉淀剂所获气凝胶为一种双相凝胶,其未经热处理时结构中含有AlOOH物相,热处理过程中首先生成过渡相铝硅尖晶石,再生成莫来石.而用(NH4)2CO3为沉淀剂时所获的气凝胶是一种单-双相混合凝胶,其DSC曲线在831.4 ℃处存在着由于Si-O-Al-O键断裂吸热而产生的吸热峰,热处理过程中铝硅尖晶石与莫来石同时生成.
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