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氧化硅气凝胶具有极低的热导率和密度,可作为很好的隔热材料,而脆弱的力学性能限制了其在隔热领域的应用。在不影响隔热效果的前提下,通过复合陶瓷纤维可增加氧化硅气凝胶的强度及韧性。试验探索了陶瓷纤维增强氧化硅气凝胶在室温下的拉伸、压缩和剪切等基本力学性能,分别研究了300℃、600℃和900℃下复合材料纤维铺层面方向的压缩性能,并采用扫描电子显微镜对高温试样微观结构进行了观察分析。结果表明:陶瓷纤维增强氧化硅气凝胶的性能表现出方向性,弹性模量在铺层面内方向与厚度方向的数值最大相差约28倍,强度极限亦然;在室温条件下,复合材料的拉伸和压缩弹性模量不同,X、Y和Z方向拉伸模量与对应的压缩模量之比分别为1.60、1.83和0.56;高温下复合材料沿厚度方向收缩,收缩量随温度升高而增大,900℃下的最大收缩量可达10.8%;高温下复合材料铺层面内方向压缩性能随温度升高而增强。
Silicon oxide airgel with very low thermal conductivity and density, can be used as a good thermal insulation material, and its weak mechanical properties limit its application in the field of insulation. Without affecting the insulation effect of the premise, through the composite ceramic fibers can increase the strength and toughness of silica airgel. The basic mechanical properties of ceramic fiber-reinforced silica aerogels at room temperature such as tensile, compressive and shear were explored. The compressive properties of the composite fiber lay in the direction of 300 ℃, 600 ℃ and 900 ℃ were investigated respectively. The microstructure of high temperature sample was observed and analyzed by scanning electron microscope. The results show that the properties of ceramic fiber-reinforced silica aerogels show the directionality. The elastic modulus has a maximum difference of 28 times in the direction of thickness and the maximum value of the strength, and at room temperature, The tensile and compressive elastic moduli are different. The ratio of the tensile modulus in the X, Y and Z directions to the corresponding compressive modulus is 1.60, 1.83 and 0.56, respectively. The composite shrinks along the thickness at high temperature, and the shrinkage increases with temperature While the maximum shrinkage at 900 ℃ can reach 10.8%. The compressive property of the composite in the plane of the composite layer increases with the increase of temperature at high temperature.