Preparation of Al ₂ O ₃ –SiC composite powder from kyanite tailings via carbothermal reduction process

Al2O3–SiC composite powders were prepared from kyanite tailings mixed with 20% excess carbon coke via carbothermal reduction (CR) reaction. The optimised synthesis condition for synthesising Al2O3–SiC composite powders was at 1600°C for 6 h. The equilibrium relationship curves of the condensed phases were presented and the temperature dependence of the phase composition was also studied. The results show that irregular Al2O3 and SiC grains first formed at 1500°C, and the elements C, O, Al, and Si randomly distributed in the each crystal particles. The amount of Al2O3–SiC composites increased with the increasing synthesis temperature and reaction time. Finally, Al2O3–SiC composite bulk materials were further prepared by pressureless sintering using the synthesised Al2O3–SiC composite powders as raw materials, and their mechanical properties were investigated in detail. All these results indicate that the CR method can offer a niche application for the development of kyanite tailings.