The mechanical behavior of ceramic-metal laminate under thermal shock

摘要

A new material system for applications involving thermal shock is proposed. The system consists of thin layers of ceramics and thinner metallic interlayers. In this study, a ceramic/metal laminate was constructed from Coor's ADS96R thin plates alternating with thinner Wesgo Cusil Active Braze Alloy interlayer foils and joined in active brazing. The maximum brazing temperature was 845 deg. C Square laminated plates were quenched in room-temperature distilled water, where a very large heat transfer coefficient exists, and therefore, severe conditions of thermal shock occur. The laminated plates, initially at temperatures of 600 and 800 deg C, were quenched at their bottom surface only in a specially designed apparatus. The temperatures at the top and the bottom surfaces of the specimens were measured by means of two thermocouples during quenching. The basic features of this architecture are described. The dominant behavior was the absence of interaction between the biaxial cracking mechanisms in a ceramic layer with those in an adjacent ceramic layer, and localization of the damage to those layers that experienced sufficient tensile stresses. The result was a dramatic increase of the residual strength after thermal shock. In addition, R-curve behavior upon mechanical loading caused by plastic deformation of the metallic interlayer was observed.