Thermal fatigue of fibrous ceramic matrix composites

This paper is devoted to the study of 2D SiC/C/SiC composites which are subjected to thermal cycling. Previous work has already shown that variation in Young's modulus can be used to monitor damage in ceramic-ceramic composites. Samples were rapidly heated by moving them up into a tubular furnace and rapidly cooled by moving them down through a gas flow, which can be either air or Ar-H2. After each thermal cycle, the uniaxial Young's modulus was measured by an ultrasonic method. The results show that a regular decrease of Young's modulus is observed in air up to 100 cycles, though it remains constant in Ar-H2. In comparison to isothermal ageing, the effects of thermal cycling on oxidation mechanisms are discussed. (orig.)