FABRICATION OF ZrO_2-SiC COMPOSITES FROM NATURAL ZIRCON ORE BY CARBOTHERMAL REDUCTION

摘要

ZrO_2-SiC composite powders were synthesized from natural zircon ore by carbothennal reduction in immerged carbon coke and the effects of synthesis temperature, carbon content, different reducing agents and oxide additives on the phase composition of the products were investigated. The phase composition of the products was characterized by X-ray diffraction. The results show that ZrO_2-SiC composite powders could be prepared from natural zircon ore by carbothermal reduction between 1500 ℃ and 1600 ℃ for 4 hours and the ideal synthetic requirement is 1600 ℃ using carbon black as reducing agent. The phase composition of zirconia in the products with 8 wt% CaO, Y_2O_3 or TiO_2 addition exists in the form of tetragonal zirconia. cubic zirconia and monoclinic zirconia respectively.