Deformation and tensile cyclic fatigue of plasma-sprayed ZrO2-8wt % Y2O3 thermal barrier coatings

Deformation (constitutive relations) of free-standing, thick thermal barrier coatings of plasma-sprayed ZrO2-8wt% Y2O3 was determined at ambient temperature in both pure tension and pure compression using cylindrical bar test specimens. The material exhibited both significant nonlinearity and hysteresis in its load-strain curves. The load-strain relations in four-point uniaxial flexure were determined from tension and compression sides and were compared with individual pure tension and compression constitutive data. Effect of sintering on deformation behavior was significant, resulting in a dramatic change in constitutive relation. Cyclic fatigue testing of the coating material in tension-tension at room temperature showed an insignificant susceptibility to fatigue, similar to the slow crack growth behavior of the material in flexure in 800degreesC air.