Thermal Stability of Low‐Oxygen Silicon Carbide Fiber (Hi‐Nicalon) Subjected to Selected Oxidation Treatment

Abstract

Low‐oxygen silicon carbide fibers (Hi‐Nicalon) were oxidized at temperatures from 1073 to 1773 K under an oxygen partial pressure of 0.25 atm. The strength of the unoxidized core was practically unaffected by the oxidation temperatures. The strength of the as‐oxidized fibers with an SiO 2 film decreased markedly with increasing oxidation temperature. When exposed subsequently to 1773 K in argon, the fibers with a SiO 2 film of 0.3–0.5 μm thickness had the best thermal stability.