Time-dependent strength degradation of a siliconized silicon carbide determined by dynamic fatigue
- Oak Ridge National Lab., TN (United States). High Temperature Materials Lab.
Both fast-fracture strength and strength as a function of stressing rate at room temperature, 1,100, and 1,400 C were measured for a siliconized SiC. The fast-fracture strength increased slightly from 386 MPa at room temperature to 424 MPa at 1,100 C and then dropped to 308 MPa at 1,400 C. The Weibull moduli at room temperature and 1,100 were 10.8 and 7.8, respectively, whereas, at 1,400 C, the Weibull modulus was 2.8. The very low Weibull modulus at 1,400 C was due to the existence of two exclusive flaw populations with very different characteristic strengths. The data were reanalyzed using two exclusive flaw populations. The ceramic showed no slow crack growth (SCG), as measured by dynamic fatigue at 1,100 C, but, at 1,400 C, an SCG parameter, n, of 15.5 was measured. Fractography showed SCG zones consisting of cracks grown out from silicon-rich areas. Time-to-failure predictions at given levels of failure probabilities were performed.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 131534
- Journal Information:
- Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 10 Vol. 78; ISSN 0002-7820; ISSN JACTAW
- Country of Publication:
- United States
- Language:
- English
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