Determination of creep behavior of thermal barrier coatings under laser imposed high thermal and stress gradient conditions

A laser sintering/creep technique has been established to determine the cre ep behavior of thermal barrier coatings under steady-state high heat flux c onditions. For a plasma sprayed zirconia-g wt. % yttria coating, a signific ant primary creep strain and a low apparent creep activation energy were ob served. Possible creep mechanisms involved include stress induced mechanica l sliding and temperature and stress enhanced cation diffusion through the splat and grain boundaries. The elastic modulus evolution, stress response, and total accumulated creep strain variation across the ceramic coating ar e simulated using a finite difference approach. The modeled creep response is consistent with experimental observations.