Degradation Mechanisms of Silicon Carbide Fibers

The effects of high temperatures on polymer‐derived Nicalon and chemically vapor‐deposited (CVD) SiC fibers have been investigated by mass‐spectrometric vapor pressure studies and by SEM observations of exposed fibers. Vaporization is kinetically limited for both materials; the predominant species vaporizing from Nicalon is SiO, whereas CO predominates in vaporization of CVD SiC fibers. The inherent instability of Nicalon and other SiC fibers in contact with matrices must be considered in ceramic composite fabrication and use.