Effect of sintering atmosphere on the microstructure evolution and mechanical properties of silicon carbide ceramics

Abstract

The densification and grain growth behaviors of β-SiC were investigated using nitrogen containing liquids by manipulating sintering atmosphere and/or by adding AlN to Al2O3-Y2O3 liquid phase sintering aids. In general, N2 atmosphere retarded β→α phase transformation and grain growth, while Ar atmosphere enhanced β→α phase transformation and the formation of platelike grains. When the sintering was carried out in N2/Ar atmosphere, substantially improved flexural strength SiC was obtained due to higher sintered density and fine grain size. AlN addition also showed a similar influence on densification behavior to the switching atmosphere. Nitrogen containing liquid is likely to inhibit phase transformation and grain growth by being incorporated into the lattice and to improve densification by retention of higher liquid amount due to higher viscosity.