Nano-SiC Ceramic Sintering at Ultra-high Pressure and High Temperature

High-density SiC ceramics doped with 2wt% Al_2O_3 additives were fabricated by ultra-high pressure and high temperature technique (4.5GPa,1250℃,20min).The structures,grain size,lattice parameters,chemical component,morphology and mechanical property of the sintered SiC ceramics were characterized by X-ray diffraction (XRD),X-ray photoelectron energy spectroscope (XPS),scanning electron microscope (SEM),energy dispersive X-ray spectroscope (EDX) and nano impress indenter. The results show that nano-SiC ceramic is fully densified by ultra-high pressure technique at relative low temperature (1250±50℃).No phase transfer or holes is found in the sintered nano-SiC ceramic.The hardness and elastic modulus of the sintered SiC ceramic with grain size of 22nm and lattice parameters of 4.355(?) are 33.TGPa and 407GPa,respectively.