纤维状γ-氧化铝/碳复合气凝胶网络结构生长调控及其自增强机制研究

The typical drawbacks of traditional oxide aerogels are poor mechanical property and low thermal resistance. In addition the fiber-reinforced aerogels composites exhibit high apparent density, heterogeneous pore structure and relatively high thermal conductivity. This project focus on the basic research on the control of network formation and self-reinforced mechanism of fibrous γ-alumina/carbon composite (γ-Al2O3/C) aerogels with low density, high strength and high thermal resistance. These composite materials will be prepared by the sol-gel method, supercritical fluid CO2 drying and thermal treatment process. Some key technologies, such as structure design, preparation process optimization，control of physical and chemical properties. The microstructure, mechanical property and thermal insulation performance of γ-Al2O3/C aerogels will be tested and analyzed. The mechanism of the fiberous γ-Al2O3’ formation, thermal insulation and self-reinforced, and the microstructure evolution of the composite aerogels in the preparation will systematically investigated. The target properties of the produced composites to be achieved include the following parameters: apparent density range of 0.15～0.20g/cm3; compressive strength over 5MPa, a Young's modulus over 280MPa；mesoporous specific surface area above 500m2/g; thermal conductivity at room temperature (25℃), 1000℃ and 1500℃ below 0.026, 0.10 and 0.30W/(m∙K), respectively.

传统氧化物气凝胶机械性能和耐温性差，纤维复合气凝胶密度大，孔结构不均匀，热导率偏高。本项目将针对低密度、高强度、耐高温纤维状γ-氧化铝/碳复合气凝胶网络结构生长调控及其自增强机制开展基础研究工作。采用溶胶-凝胶法、二氧化碳超临界干燥及热处理技术，研究纤维状γ-氧化铝/碳复合气凝胶的结构设计、制备工艺优化、物化性能控制等关键技术。对该复合气凝胶进行微观组织结构、力学性能和隔热性能进行测试分析，并总结出其在制备过程中纤维状γ-氧化铝生长机理、自增强机制、隔热机理及微观组织结构的演变规律。制备出满足如下性能的纤维状γ-氧化铝/碳复合气凝胶材料：表观密度在 0.15～0.20g/cm3；压缩强度在≥5MPa，杨氏模量≥280Mpa；介孔比表面积≥500m2/g；室温（25℃）热导率≤0.026W/(m∙K)，1000℃热导率≤0.10W/(m∙K)，1500℃热导率≤0.30W/(m∙K)。

传统氧化物气凝胶机械性能和耐温性差，纤维复合气凝胶密度大，孔结构不均匀，热导率偏高。本项目针对低密度、高强度、耐高温纤维状γ-氧化铝/碳复合气凝胶网络结构生长调控及其自增强机制开展基础研究工作。采用溶胶-凝胶法、二氧化碳超临界干燥及热处理技术，研究了纤维状γ-氧化铝/碳复合气凝胶的结构设计、制备工艺优化、物化性能控制等关键技术。对该复合气凝胶进行微观组织结构、力学性能和隔热性能进行了测试分析，并总结了其在制备过程中纤维状γ-氧化铝生长机理、自增强机制、隔热机理及微观组织结构的演变规律。最终制备出的纤维状γ-氧化铝/碳复合气凝胶材料的相关性能如下：表观密度在 0.15～0.20g/cm3；压缩强度在5.0～9.1MPa，杨氏模量在280～475Mpa；介孔比表面积在579～831m2/g；室温（25℃）热导率在0.026～0.049W/(mK)，1000℃热导率在0.100～0.140W/(mK)，1500℃热导率在0.250～0.280W/(mK)。