Abstract

Silicon carbide powder was prepared from mixtures of Sangdong silica sand and carbon black by SHS (Self propagating High temperature Synthesis) method which utilizes magnesiothermic reduction of silica. In the powder preparation process, the reacted powder was leached by chloric acid to remove the magnesium oxide and was subsequently roasted to remove free carbon. The impurities were mostly eliminated by hot acid treatment. The resultant SiC powder showed the mean particle size of 0.22 µtextrmm and the specific surface area of 66.55 m2/g. The SiC powder was mixed with 1 wt% of boron and of carbon to increase densification rate. The mixed powder was pressed and sintered pressurelessly at 2100°C for 30 min in argon gas. The sintered body showed the hardness of 2550 kgcdotf/mm2 and the fracture toughness, KIC of 3.47 MN/m3/2.