Microstructural development of liquid-phase-sintered silicon carbide during annealing with uniaxial pressure

beta-SiC powders containing 1.1 wt.% alpha-SiC particles as seeds were hot-pressed at 1800 degreesC and then annealed at 2000 degreesC under 25 MPa uniaxial pressure to enhance grain growth. Microstructural development during annealing with pressure was investigated quantitatively and statistically using image analysis. The bimodal grain-thickness distribution in samples annealed with pressure was obtained due to abnormal grain growth of some grains. In situ-toughened microstructure has been developed after 3-h annealing. The grain-thickness and aspect ratio of large grains increase with annealing time, but grain growth comes mainly from increases in thickness after 3-h annealing, owing to the impingement of large gains. Typical flexural strength and fracture toughness of 4-h 2 annealed sample were similar to500 MPa and similar to7.5 MPa m(1/2), respectively. (C) 2002 Elsevier Science Ltd. All rights reserved.