Utilization of Chemically Synthesized Fine Powders of SiC/Al₂O₃Composites for Sintering

Abstract

Fine powders of (Al2O3)100–x(SiC)x (0 ≤ x ≤ 50) composites were prepared by chemical route (named as pyrophoric technique) to achieve a uniform mixture of SiC in an alumina matrix. The chemically synthesized fine SiC/Al2O3 composite powders were sintered to form composites at 1450°C which is well below the sintering temperature of SiC. Sintering was performed in an argon atmosphere. Highly dense SiC/Al2O3 microstructures were achieved. An improvement in bulk density and hardness has been achieved for SiC/Al2O3 composites with 20 wt% of SiC. Hexagonal-shaped grains have been obtained in (Al2O3)50(SiC)50 composite with well-connected grain boundaries. The peak position of alumina in SiC/Al2O3 composites shifts toward lower wavenumbers in Fourier transform infrared spectroscopy and higher wavenumbers in Raman spectroscopy due to the incorporation of SiC in the composites. The optical band gap decreases with the addition of SiC and the composite behaves more like a semiconductor rather than an insulator. These properties make SiC/Al2O3 composites attractive for various industrial applications.