Assessment of damage induced by thermal shock in SiC-fiber-reinforced borosilicate glass composites

Glass matrix composites reinforced with Nicalon silicon carbide fibres were subjected to thermal shock by the water-quench technique. Analysis of dama ge evolution in the material was carried out by means of measurements of th e dynamic mechanical properties, with a forced resonance technique, and of interfacial properties by fiber push-out testing. Samples which were subjec ted to thermal shocks from 650 degrees C to room temperature exhibited chan ges in Young's modulus and internal friction with increasing number of shoc ks, indicating damage development in the form of creation of new internal s urfaces. Fiber push-out tests showed that no significant changes in the pro perties of the fiber/matrix interface occurred, suggesting that damage in t he composite was concentrated mainly in the development of matrix microcrac king with less incidence of oxidation effects on the interface. The results from this analysis show that composite damage can be detected non-destruct ively by resonant analysis before any significant interfacial degradation o ccurs. (C) 1999 Elsevier Science Ltd. All rights reserved.