Multiple-Approach Evaluation of WSP Coatings Adhesion/Cohesion Strength

Adhesion/cohesion testing represents one of the most common methods for benchmarking and optimization of thermal spray coatings. However, due to the inhomogeneous coating microstructure, such testing may be quite troublesome, namely due to the presence of pores, microcracks and phase boundaries. In this study, adhesion/cohesion strength of representative metallic and ceramic coatings deposited by Water Stabilized Plasma (WSP) spraying was evaluated by different methods, namely tensile adhesion test, shear load resistance test and newly utilized pin test. Combination of various methods enabled evaluation of the splat bonding quality in different loading modes. Advantages and drawbacks of various methods for testing of WSP coatings are discussed. Dominant coating failure micromechanisms were determined by supplementary fractographic analysis.