Adhesion strength evaluation for plasma-sprayed coatings based on intensity of singular stress

This paper presents a new test method, including coated specimen, shear testing procedure, and algorithm for evaluation of critical intensity of singular stress for coating, for more accurate and complete characterization of adhesion strength. A procedure for determining the critical intensity of singular stress for coating is presented in this paper. In this paper, the coated specimen has been analysed in terms of the intensity of singular stress field. The adhesion strength of plasma-sprayed coatings was estimated in terms of the intensity of singular stresses in the vicinity of the free edge of the coating. The finite element analysis for normal and tensile stress distributions of the coated specimens are obtained by using different mesh sizes (fine, medium, and coarse size). Tensile testing of flat metal samples with plasma-sprayed coatings of Co-Cr alloy of various thicknesses (90, 100, 160 mm) was performed. The results show that the adhesion strength of the tested coatings can be represented by a critical stress of 1.34, 0.94, 0.88 MPa m0.43 for thicknesses of 90, 100, 160 mm, respectively.