Fabrication of highly dense pure SiC ceramics via the HTPVT method

Abstract

A high-temperature physical vapor transport (HTPVT) method was used to grow highly dense SiC ceramics free of sintering aids, and the effects of growth time and temperature upon the grain size, growth rate, thickness and orientation of silicon carbide were explored. Silicon carbide ceramics with a thickness of 8mm and a bulk density of 3.208g/cm−3 were obtained after 4h of growth. The silicon carbide texture exhibited a preferred orientation along (000l) planes. The degree of grain size and orientation of the silicon carbide increased with increased growth time, and the growth rate increased with the growth temperature and temperature gradient. Silicon carbide ceramics exhibited a bending strength of only 290±34MPa, primarily due to the large grain size (average grain size: 2mm), and a Vickers hardness of 29.7±0.6GPa.