The Model for Estimating the Failure Mechanism of Tensioned Plasma-Sprayed Zirconia Ceramic Hard Coating

Abstract

Loading flat coated specimens with tensile forces is a universal method to determine the nature of fracture of hard coatings in maritime applications. Such an approach allows the determination of the shear strength at the interfaces between layers and the cohesive properties. Thus, the authors studied the fracturing processes of plasma-sprayed yttria-stabilized zirconia two-layer coatings under the action of tensile forces. The results revealed cracking characteristics in the outer ceramic layer and delamination of flat metal specimens. An analytical method led to normal stress determination in the coating. It also exhibited shear stresses at the bond coat-substrate interface and the top coat-bond coat interfaces. The results include normal and shear stress distributions before and after fragmentation of the ceramic top layer. Tested substrate, the metal bond coat, and the ceramic top coat exhibit a modulus of elasticity of 196, 142, and 47 GPa, respectively. Engineers could apply the proposed methodology and the mathematical analysis to study the causes of cracks and delamination between layers.