Abstract: The Al_2O_3-Si material has been prepared by using fused corundum aggregates and fines, 5%-8% Si powder as starting materials and sulfite lye as binder. Changes in phase composition and microstructure of Al_2O_3-Si material during heating at 1000-1600 ℃ under carbon embedded condition have been studied. The results show that after firing at 1200 ℃, Si begins to react with CO to form SiC whiskers which are interlocked with each other within the pores of the materials. After firing at 1300-1400 ℃, SiC whiskers are found to increase noticeably in amount together with growth in crystal size. The SiC whiskers are observed to be interspersed within the corundum skeleton structure mostly in the form of continuous interlocking network. Minor amount of O'-SiAlON crystals are observed at 1400 ℃. After firing at 1500-1600 ℃, SiC continues to grow in crystal size, most of them exhibit bending and arborization tendency. The residual Si is melt exhibiting plastic deformation and takes as sintering aid.

Key words: corundum%Si%phase composition%microstructure