【摘要】 采用浸渍法制备SiO₂凝胶/铝硅纤维复合材料。研究Si粉质量分数为0%,0.2%,0.4%,0.6%和0.8%时,SiO₂凝胶/铝硅纤维复合材料的微观形貌、体积密度、回弹率和物相组成。结果表明:Si粉质量分数低于0.6%时,其氧化产生的体积膨胀填补了纤维与凝胶间的裂纹,体积密度由0.468g/cm³增大到0.723g/cm³,回弹率由43.1%升高为59.6%,并且Si粉高温下的结晶化抑制了纤维析晶和促进了辉石的生成,这是材料的力学性能提高及高温损坏程度降低的重要原因;Si粉质量分数为0.8%时,高温下的Si粉产生了过分的体积膨胀,导致复合材料内部出现较大裂纹,压缩回弹率降低为44.5%。更多还原

【Abstract】 SiO₂ gel/alumina-silica fibers composites were prepared by impregnation method.Silicon powder with different mass fractions of 0%,0.2%,0.4%,0.6%and 0.8% was added in the slurry,and the effects of silicon powder on the microstructure,bulk density,compression-resilience ratio and phase compositions of the SiO₂ gel/alumina-silica fiber composites were investigated.The results show that when the mass fraction of the silicon powder is lower than 0.6%,the volume expansion of silicon resulting from the silicon oxidation fills the cracks between fibers and gel,the volume density of the composites increases from 0.468g/cm³ to 0.723g/cm³,and the resilience ratios increase from43.1%to 59.6%.Besides,it is found that the mechanical property is improved and the degree of high-temperature damage for the composites is decreased by the silicon crystallization,which restrains the fibers crystallization and facilitates the generation of pyroxene.However,when the mass fraction of silicon powder is 0.8%,the compression-resilience ratio of the composites significantly declines to44.5%,which is attributed to the big cracks generated from the excessive volume expansion of silicon powder at high temperature.更多还原