PHYSICAL, THERMAL, AND MECHANICAL PROPERTIES OF Al2O3-CaAl12O19 COMPOSITES PROCESSED BY IN-SITU REACTION SINTERING

The physical, thermal, and mechanical characteristics of Al 2 O 3 -CaAl 12 O 19 composites processed by in-situ reaction sintering are described.  The presence of CaAl 12 O 19 phase in Al 2 O 3 matrix has significant effect on the physical, thermal and mechanical properties of the final products. The porosity values increased rapidly for higher CaAl 12 O 19 content, whereas the bulk density of the composite product decreased with increasing in CaAl 12 O 19 content. The thermal expansion and densification behaviour results showed that the presence of CaAl 12 O 19 phase hinders the processes of sintering and densification of alumina matrix. Although the presence of CaAl 12 O 19 caused the reduction of hardness, the Al 2 O 3 -CaAl 12 O 19 composites have improved fracture toughness when compared to alumina but not for CaAl 12 O 19 exceeds 50 wt%. Keywords : Al 2 O 3 -CaAl 12 O 19 composites, in-situ reaction sintering, hardness, fracture, toughness