Flaw-tolerance and R-curve behavior of liquid-phase-sintered silicon carbides with different microstructures
Journal Article
·
· Journal of the American Ceramic Society
- Korea Advanced Inst. of Science and Technology, Taejon (Korea, Republic of). Dept. of Ceramic Science and Engineering
{beta}-SiC powder containing 6 wt% Al{sub 2}O{sub 3} and 4 wt% Y{sub 2}O{sub 3} as sintering additives was pressureless sintered at 2,000 C for 1 h (AYE-SiC) and 3 h (AYP-SiC). AYE-SiC consisted of an equiaxed grain structure and AYP-SiC exhibited a microstructure with platelike grains as a result of grain growth related to {beta} {yields} {alpha} phase transformation during sintering. R-curve behavior and flaw tolerance for these silicon carbides were evaluated by the indentation-strength technique. For comparison, the R-curve behavior of conventional sintered, boron- and carbon-doped SiC (SS-SiC) was evaluated. AYE-SiC and AYP-SiC exhibited rising R-curve behavior with toughening exponents of m = 0.042 and m = 0.135, respectively. AYP-SiC exhibited better flaw tolerance and more sharply rising R-curve behavior than AYE-SiC. The more sharply rising R-curve behavior and the better flaw tolerance of AYP-SiC were attributed mainly to grain bridging of crack faces by platelike grains. Because of the high degree of transgranular fracture, SS-SiC exhibited a flat R-curve despite a microstructural feature with platelike grains.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 182643
- Journal Information:
- Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 1 Vol. 78; ISSN 0002-7820; ISSN JACTAW
- Country of Publication:
- United States
- Language:
- English
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