Microstructural development of silicon carbide containing large seed grains
- Seoul City Univ. (Korea, Republic of). Dept. of Materials Science and Engineering
- National Inst. for Research in Inorganic Materials, Ibaraki (Japan)
- Denki Kagaku Kogyo Co., Tokyo (Japan). Research Center
Fine ({approximately}0.1 {micro}m) {beta}-SiC powders, with 3.3 wt% large ({approximately}0.44 {micro}m) {alpha}-SiC or {beta}-SiC particles (seeds) added, were hot-pressed at 1,750 C and then annealed at 1,850 C to enhance grain growth. Microstructural development during annealing was investigated using image analysis. The introduction of larger seeds into {beta}-SiC accelerated the grain growth of elongated large grains during annealing, in which no appreciable {beta}{yields}{alpha} phase transformation occurred. The growth of matrix grains in materials with {beta}-SiC seeds was slower than that in materials with {alpha}-SiC seeds. The material with {beta}-SiC seeds, which was annealed at 1,850 C for 4 h, had a bimodal microstructure of small matrix grains and large elongated grains. In contrast, the material with {alpha}-SiC seeds, also annealed at 1,850 C for 4 h, had a uniform microstructure consisting of elongated grains. The fracture toughnesses of the annealed materials with {alpha}-SiC and {beta}-SiC seeds were 5.5 and 5.4 MPa{center_dot}m{sup 1/2}, respectively. Such results suggested that further optimization of microstructure should be possible with {beta}-SiC seeds, because of the remnant driving force for grain growth caused by the bimodal microstructure.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 455160
- Journal Information:
- Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 1 Vol. 80; ISSN 0002-7820; ISSN JACTAW
- Country of Publication:
- United States
- Language:
- English
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