Effect of boron carbide additive and sintering temperature - Dwelling time on silicon carbide properties

Abstract

Sintering temperature and composition are two important factors that affect the properties of ceramic materials. In this study, the effects of sintering temperature, dwelling time, intermediate dwell, and B4C content on the density, microstructure, and elastic properties of dense SiC ceramics were investigated. 1.5 wt% C and 0.25 wt% or 0.5 wt% B4C were added to SiC which was spark plasma sintered (SPS) at 1900 °C, 1950 °C, or 2000 °C under a pressure of 50 MPa in flowing argon with an intermediate dwell at 1400 °C (for 1 or 30 min). The results of the sintering study showed that the best microstructure was obtained in the sample sintered at 1900 °C for 10 min with an intermediate dwell at 1400 °C for 30 min. Under these conditions, the sintered sample has reached full density (>99%) with elastic, shear and bulk modulus values of 436 GPa, 184 GPa and 233 GPa, respectively. In addition, it was observed that 0.5 wt% B4C content gave preferred results over 0.25 wt% B4C content. These conditions allow the production of fully dense silicon carbide ceramics with fine-grained microstructure.