초록
The effect of the additives, $Y_2O_3$ and MgO, on the sintering and properties of $Al_2O_3-TiC$ composites was investigated. It is known that MgO is used as additive for improving densification and $Y_2O_3$ is applied as sintering aid. In this study, the amounts of TiC were varied in the range of 30-47 wt%. The 0.5 wt% MgO and also varied amounts of $Y_2O_3$ from 0.3 to 1 wt% were added into the composites. The sintering of $Al_2O_3-TiC$ composites was performed in a graphite-heating element furnace at different sintering temperature, 1700 and $1900\;^{\circ}C$, for 2 hr under an argon atmosphere. The results demonstrated that the properties of the composites sintered at $1700\;^{\circ}C$ were much better than those sintered at $1900\;^{\circ}C$. The comparisons on physical properties, mechanical properties and microstructure of composites with and without additives were reported. Comparing with other samples, $Al_2O_3-30wt%TiC$ composites with 0.5wt% MgO and $1\;wt%Y_2O_3$ exhibited the highest density of approximately 98% of theoretical and flexural strength of 302 MPa.