Stress-rupture, overstrerssing, and a new methodology to assess the high-temperature durability and reliability of CFCCs

A testing methodology is proposed to assess the durability and reliability of non-oxide continuous fiber-reinforced ceramic composites for high temperature applications. The strategy is based on determining the reliability of these materials when subjected to random loading schedules consisting of mechanical load and temperature spikes that are superimposed upon otherwise constant stress and temperature values. The frequency and magnitude of the mechanical load and temperature spikes would be representative of the number and characteristics of the transients that are associated with a particular industrial application and that are expected to occur over the life of the component. The effect of overstressing on the stress-rupture behavior of a ceramic grade (CG) Nicalon(TM) fiber-reinforced silicon carbide (SiC) matrix composite was investigated and results are presented from tests conducted in ambient air at 950 degreesC.