In-situ Reinforced SiC Ceramics

SiC ceramics with rod-like grains were obtained by pressureless sintering of β-SiC powders with Y2O3and Al2O3 as additives. The materials were densified based on liquid phase sintering mechanism. Thephase transformation of 3C→4H in SiC occurred during sintering, which was associated with the formationof rod-like grains. The mechanical properties of the materials depended on the aspect ratio of SiC grains,on the optimum, the maximum values of the flexural strength and fracture toughness reached 620MPaand 6.1MPa.m1/2 respectively. The trajectory of indentation crack revealed that the crack deflection andgrain-bridging were the main tougheing mechanisms due to the weak grain-boundary.