Ultra-fast high temperature sintering (UHS) of silicon carbide (SiC) ceramics with oxide-based sintering additives

Abstract

SiC is an attractive ceramic material for a wide range of industries. There exist many techniques for sintering SiC to fabricate products of interest. However, these conventional techniques can be time consuming and/or energy intensive, driving up costs of production. A recently discovered technique known as Ultra-fast High Temperature Sintering (UHS) promises rapid sintering times. For any sintering process, the mechanism of ceramic sintering is enhanced by addition of metal oxides as sintering aids. For SiC systems, Al2O3 and Y2O3 powders in the ratio of 6:4 is often used as sintering aid since this ratio forms a eutectic point in the phase diagram that allows for lower sintering temperature. However, the possibilities of a different sintering aid ratio having positive effects on density and/or sintering temperatures cannot be ruled out as the exact mechanisms of Liquid Phase Sintering for SiC with UHS is not well understood. This study aims to uncover the effects of varying the ratio of sintering aids, by observing the effects of varying ratios of Al2O3 and Y2O3. While there were difficulties in demonstrating any effects, due to unexpectedly low densities obtained, this study serves to highlight the challenges faced in UHS and provides recommendations for future work.