Determination and analysis of crack growth resistance in plasma-sprayed thermal barrier coatings

Ceramic thermal barrier coatings (TBCs) are increasingly applied to enhance the performance of advanced gas turbine engines. However, the delamination cracks initiated in these coatings limit their applications. In this research, a sandwiched four-point bend specimen is used to evaluate the crack growth resistance in plasma-sprayed TBCs. Well controlled, stable and measurable crack extension is obtained. A rising crack growth resistance curve is found. The steady state strain energy release rate is obtained to be about 170 J/m2. The delamination crack evolution behavior is in situ observed and simulated by the finite element analysis based on a crack bridging model.