Effect of YAG on $\beta$-Sic-$ZrB_2$ Composites

$\beta$-Sic-$ZrB_2$계 복합체에 미치는 YAG의 영향

The mechanical and electrical properties of the hot-pressed and annealed $\beta$-Sic-$ZrB_2$ electroconductive ceramic composites were investigated as function of the liquid forming additives of $Al_{2}O_{3}+Y_{2}O_{3}$. Phase analysis of composites by XRD revealed $\alpha$-SiC(6H), $ZrB_2$, and YAG($Al_{5}Y_{3}O_{12}$). The relative density of composites were increased with increasing $Al_{2}O_{3}+Y_{2}O_{3}$ contents. The flexural strength showed the highest value of 390.6MPa for composites added with 20wt% $Al_{2}O_{3}+Y_{2}O_{3}$ additives at room temperature. Owing to crack deflection, crack bridging. phase transition and YAG of fracture toughness mechanism. the fracture toughness showed the highest value of 6.3MPa${\cdot}m^{1/2}$ for composites added with 24wt% $Al_{2}O_{3}+Y_{2}O_{3}$ additives at room temperature. The electrical resistivity of the composites was all positive temperature coefficient resistance (PTCR) in the temperature range of 25$^{\circ}C$ to 900$^{\circ}C$.