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以正硅酸乙酯为原料,通过二甲基二乙氧基硅烷引入碳元素,以乙醇为溶剂,盐酸和氨水为催化剂,莫来石纤维为增强相,采用溶胶–凝胶、超临界干燥和1 200℃高温裂解工艺制备Si-C-O气凝胶隔热复合材料,并对材料的结构和性能进行了分析和表征。结果显示:1 200℃裂解得到的Si-C-O气凝胶复合材料为黑色且加工成型性较好,纤维表观体积密度为0.15 g/cm3时,800℃和1 000℃热导率分别为0.031 9 W/(m K)和0.043 0W/(m K)。纤维表观体积密度增大(0.15～0.30 g/cm3),复合材料的拉伸和压缩强度增大,密度为0.25 g/cm3时,抗弯强度最大。1 200℃裂解得到的Si-C-O气凝胶的比表面积为217.7 m2/g,空气中1 000℃煅烧后,比表面积为208.6 m2/g。Si-C-O气凝胶复合材料在1 000℃空气中煅烧后没有出现收缩。
Using tetraethyl orthosilicate as raw material, carbon was introduced by dimethyl diethoxysilane, ethanol as solvent, hydrochloric acid and ammonia as catalyst, mullite fiber as reinforcing phase, and sol-gel, supercritical drying And 1 200 ℃ pyrolysis process Si-CO airgel insulation composite material, and the structure and properties of the material were analyzed and characterized. The results show that the thermal conductivity at 800 ℃ and 1 000 ℃ of Si-CO aerogels composites obtained by pyrolysis at 200 ℃ is black and the formability is good, and the apparent bulk density of fiber is 0.15 g / 9 W / (m K) and 0.043 0 W / (m K). The apparent bulk density of fiber increased (0.15 ~ 0.30 g / cm3), the tensile strength and compressive strength of the composites increased, and the flexural strength reached the maximum at the density of 0.25 g / cm3. The specific surface area of Si-C-O airgel prepared by pyrolysis at 200 ℃ was 217.7 m2 / g. After calcination in air at 1 000 ℃, the specific surface area was 208.6 m2 / g. Si-C-O airgel composites did not shrink after calcination in air at 1000 ° C.