Heat Treatments as a Method of Protection for a Ceramic Fiber—Glass Matrix Composite

Thermal exposure in air has been shown to embrittle a ceramic fiber‐glass matrix composite by the infiltration of oxygen to the fiber‐matrix interface. Samples exposed at sufficiently high temperatures demonstrate less embrittlement and less strength loss than samples exposed at intermediate temperatures, because of a material flow which seals the surface. It is shown that the protection against embrittlement provided by a short, high‐temperature thermal treatment remains in force for materials subsequently exposed to intermediate temperatures under both loaded and unloaded conditions.