【摘 要】
：
气凝胶具有较好的耐高温和热稳定性,但是Al2O3气凝胶在高的烧结温度下,会发生一系列的相变导致体积收缩、比表面积下降,对其高温隔热、力学等性能可能产生重要影响,极端
【机 构】
：
国防科学技术大学航天科学与工程学院新型陶瓷纤维及其复合材料重点实验室,湖南长沙410073国防科学技术大学航天科学与工程学院新型陶瓷纤维及其复合材料重点实验室,湖南长沙410073;洛阳特种材料研究院
【出 处】
：
2016’中国溶胶-凝胶学术研讨会暨国际论坛
论文部分内容阅读
气凝胶具有较好的耐高温和热稳定性,但是Al2O3气凝胶在高的烧结温度下,会发生一系列的相变导致体积收缩、比表面积下降,对其高温隔热、力学等性能可能产生重要影响,极端情况下会使材料失去隔热效果,导致材料失效.为了探究高温烧结机制,本文分别以仲丁醇铝(ASB)和正硅酸乙酯(TEOS)为铝源和硅源,通过溶胶-凝胶和超临界干燥工艺制备出Al2O3-SiO2气凝胶.采用FT-IR、XRD、TG-DSC、SEM、BET等对Al2O3-SiO2气凝胶在高温下的结构和性能进行分析和表征,结果表明：Al2O3-SiO2气凝胶的热重-差示曲线存在三次失重过程,主要包括物理吸附水和醇溶剂的去除,以及未完全水解的Al-OR基团的分解.Al2O3-SiO2气凝胶经1200℃热处理900s后,气凝胶结构中出现θ-Al2O3,随着热处理时间(9000s)的延长未发生α-Al2O3晶型转变,气凝胶在1200℃具有较好的耐温性能；Si-O-Si伸缩振动峰在1200℃热处理后基本消失,出现了Al-O-Si吸收峰.经过900℃热处理,气凝胶内部开始出现大孔；随着热处理温度的增加,气凝胶比表面积下降,1200℃热处理1500s后,能具有较高的比表面积170m2/g,材料具有较好的耐温性.
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