Al2O3-SiO2复合纳米气凝胶材料耐高温性能研究OA

Using tetraethyl orthosilicate(TEOS)and aluminum chloride hexahydrate(AlCl3·6H2O)as the mixed precursor and propylene oxide as the network trapping agent,the aerogel with different molar ratios of Al2O3-SiO2 was prepared by sol-gel process and carbon dioxide supercritical drying method without adding chelating agent.The samples were heat-treated at 600 ℃,800 ℃,1 000 ℃ and 1 200 ℃ respectively,and the micro-morphology,structure and thermal stability of the Al2O3-SiO2 composite aerogel were characterized by Fourier infrared spectros-copy,scanning electron microscopy,X-ray diffractometer,specific surface area analyzer,thermogravimetric differ-ential thermal analyzer and other instruments.The results show that when AlCl3·6H2 O∶TEOS=8∶1,the thermal conductivity of Al2O3-SiO2 aerogel samples after heat treatment at 1 000 ℃ and 1 200 ℃ is 0.062 1 W/m·K and 0.080 3 W/m·K,respectively.The pore size is more uniform and the mesoporous structure is preserved above 1 000℃.At normal temperature and 1 200 ℃,the specific surface area is 617.14 m2/g and 102.9 m2/g,with uniform mesoporous structure(pore diameter is 8～32 nm),and the pore size is lower than the average free path of air at normal temperature.After heat treatment at 1 200 ℃,the total weight loss rate of the sample is 16.3％,which proves the sample has good high temperature thermal stability.