Interface failure behavior of YSZ thermal barrier coatings during thermal shock

Abstract

A high temperature interface deformation test system was built for failure analysis of YSZ thermal barrier coatings during 1100 °C thermal shock and thermal cycles. The strain distribution and evolution law near the thermal barrier coatings interface were in-situ real-time observed and measured by the developed high temperature interface deformation test system. After repeated thermal shock, crack initiation vertical to the interface will periodically come into being at the location of strain concentration area near the ceramic top coat surface. These cracks extend from the top coat surface to the interface, of which the period of crack agrees well with the theoretical analysis. EDS analysis indicate that the inter-diffusion lead to an influential tensile strain in the interface area and bond coat layer. Tensile tests indicate that with increase of thermal shock times, not only the bonding strength of the TBCs decreases, but also the tensile failure location change significantly.