Effect of Microstructure on the Thermomechanical Properties of SIC Fibers
Abstract
Polymer-derived SiC-based fibers with fine-diameter (10-15 mm) and high strength (3 GPa) were prepared with carbon-rich and near-stoichiometric compositions. Fiber tensile strengths were determined after heat treatments at temperatures up to 1950 deg C in non-oxidizing atmospheres and up to 1250 deg C in air. The creep resistance of fibers was assessed using bend stress relaxation (BSR) measurements. Fibers showed excellent strength retention after heat treatments in non-oxidiziing atmospheres at temperatures up to 1700 deg C for the carbon-rich fibers and up to 1950 deg C for the near-stoichiometric fibers. The near-stoichiometric fibers also showed considerably better strength retention after heat treatments in air. Creep resistance of the as-fabricated fibers was greatly improved by high-temperature heat treatments. Heat-treated near-stoichiometric fibers could be prepared with 3 GPa tensile strengths and BSR creep behavior which was significantly better than that reported for i-Nicalon TM Type S fibers. It was also shown that the near-stoichiometric fibers could be coated with hexagonal BN using an in-situ processing method.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1998
- Accession Number
- ADA397423
Entities
People
- J. H. Simmons
- M. D. Sacks
Organizations
- University of Florida