Effect of Silicon Powder on Properties of SiO₂ Gel/Alumina-silica Fibers Composites

• Main Authors: ZHANG Jing, TIAN Geng, LIU Jia-chen
• Format: Article
• Language: zho
• Published: Journal of Materials Engineering 2016-10-01
• Series: Journal of Materials Engineering
• Subjects: silicon powder; SiO₂ gel/alumina-silica fiber composite; high-temperature damage; mechanical property
• Online Access: http://jme.biam.ac.cn/CN/10.11868/j.issn.1001-4381.2016.10.014

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 from 43.1% 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 to 44.5%, which is attributed to the big cracks generated from the excessive volume expansion of silicon powder at high temperature.