Cavitation Erosion of Coation Materials Based on the Propagation of Stress Waves

Abstract

Based on analyses of stress wave propagation, cavitation erosion was studied on coating materials such as welding deposit metals and platings. The MDPR (mean depth of penetration rate) increased, decreased or kept constant as a function of the coating thickness depending on the combination of the acoustic impedances of the coating and its substrate. A critical thickness T_c was observed, above which the MDPR kept constant for all coatings. The critical thickness T_c and the MDPR at a given thickness was predicted in terms of physical parameters of the material such as the modulus of longitudinal elasticity and the density of both coating and its substrate. In case of a very thin coating, the time to entire removal of coating layer was greatly influenced by the combination of the acoustic impedances as well as by the erosion resistance of the materials. Thus, it was concluded that the erosion life of the coatings can be predicted from analyses of the stress wave propagation.