Effect of Microstructure on the Thermomechanical Properties of SiC Fibers
Abstract
The effect of non-oxidizing heat treatments on the creep resistance and strength retention for carbon-rich and near-stoichiometric SiC-based fibers was investigated. Carbon-rich fibers showed excellent strength retention and greatly improved creep resistance when heat treated at 1700 deg C in argon. This was attributed to the increased grain sizes and possibly more highly crystallized graphitic carbon. The measured creep resistance was comparable to or better than observed for as-prepared near-stoichiometric fibers. This result indicated that diffusion is inhibited in SiC-based fibers which contain larger amounts of excess carbon. The creep resistance of the near-stoichiometric fibers was also greatly enhanced by annealing heat treatments at 1940 deg C. This was attributed to increased grain size and possibly to reduced boron concentration within the bulk fiber. The combination of high strength (approximately equal 3 GPa) and high creep resistance that was obtained for the annealed near-stoichiometric fibers has not been observed for other SiC based fibers.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 08, 2001
- Accession Number
- ADA388218
Entities
People
- M. D. Sacks
Organizations
- Georgia Tech