Ultra-high pressure densification and properties of nanostructured SiC

Abstract

Cubic SiC nano-powder particles were synthesized by a sal-gel process with an average grains size of 9.5 nm which were subsequently densified by using a high-pressure "anvil-type with hollows" apparatus at a pressure of 4 GPa in order to obtain nanostructured bulk ceramic compacts. The density obtained was gt 98% at a sintering temperature of 1500 degrees C with a holding time of only 60s. The calculation of the average crystallite size (D) was performed on the basis of the full width at half maximum intensity (FWHM) of the XRD peaks. Williamson-Hall plots were used to separate the effect of the size and strain in the nanostructured SiC compacts. Sintered nanostructured SiC ceramic exhibits hardness and elastic modulus of 32-420 GPa respectively. Wear properties were investigated and the average value of dynamic friction coefficient obtained was 0.16.