Evaluation of mechanical properties of ceramic coatings on a metal substrate

Nanoindentation and tensile tests were performed for TiN coatings on a stainless steel substrate to investigate the indentation induced deformation behavior of the coatings and the adhesion of the coating–substrate interface. Load–displacement curves show the transition of plastic deformation state from coating only to coating–substrate composite in a penetration depth of 1/10 of the coating thickness, which is approximately two times smaller than that of metal coatings. We employed two specimens with different interface characteristics for the evaluation of the adhesion. The tensile test can clearly detect the difference by the analysis of statistics of extremes for the maximum crack spacing, while the indentation results show no difference, suggesting that the tensile test is superior in detecting the adhesion of the coating–substrate interface.