期刊Oxidation behavior and mechanical properties of low-oxygen SiC fibers prepared by vacuum heat-treatment of electron-beam-cured poly(carbosilane) precursor.pdfVIP

J O U R N A L O F M A T E R I A L S S C I E N C E 3 8 (2 0 0 3 ) 1653 – 1660 Oxidation behavior and mechanical properties of low-oxygen SiC fibers prepared by vacuum heat-treatment of electron-beam-cured poly(carbosilane) precursor T. SHIMOO, K. OKAMURA Department of Metallurgy and Materials Science, Graduate School of Engineering, Osaka Prefecture University, 1-1, Gakuen-cho, Sakai, 599-8531 Osaka, Japan E-mail: shimoo@mtl.osakafu-u.ac.jp W. MUTOH Graduate School of Engineering, Osaka Prefecture University, 1-1, Gakuen-cho, Sakai, 599-8531 Osaka, Japan EB-cured PCS fibers were heat-treated at 1273–1673 K under a reduced pressure of 1.33 Pa, and subsequently they were exposed to 1773 K in air. The thermal stability and oxidation resistance of the fibers were investigated through TG, XRD analysis, specific resistivity measurement, SEM observation and tensile tests. The oxidation rates at initial stage are thought to be strongly dependent upon the microstructure of the fibers in the as-heat treated state and the presence of water vapor. Incomplete ceramization and the occurrence of active-oxidation during heat-treatment yielded poor oxidation resistance to the fibers. The oxidation caused the grain growth of SiC, drop of resistivity and degradation of strength. The oxidation of the fibers was retarded at later stage. The fibers heat-treated at 1573 K had high strength and high oxidation resistance. C 2003 Kluwer Academic Publishers 1. Introduction However, the heat-treatment above 1673 K caused the Poly(carbosilane)-derived silicon carbide fibers are of active-oxidation of SiC grains in the fibers, resulting great importance as a reinforcing material for ceramic- in marked degradation of fiber strength. The oxidation matrix composites for a variety of high-temperature resistance also is one of co