Investigation on the failure mechanism of graphite-like carbon coatings under cavitation erosion in distilled water

Abstract

In this study, the use of graphite-like carbon (GLC) coatings deposited via magnetron sputtering to enhance the cavitation erosion (CE) resistance of 316L stainless steel is presented. The cross-sectional analysis and Rockwell testing show that the GLC coating exhibits the dense structure and good adhesion. The hardness and elastic modulus of the coating measured by nanoindentation reached 17.3 GPa and 197.3 GPa, respectively. Furthermore, the GLC coating exhibits excellent corrosion resistance upon electrochemical measurements. With the analysis of surface topography, chemical composition and carbon bonds, a model describing the CE failure mechanism of the GLC coatings is presented. The CE failure of the GLC can be divided into four primary stages: an initial generation of striated bulges with the release of internal stress accompanied with graphitization, followed by the generation of micro-cracks, the coating spallation with the interlinked micro-cracks and the final coating delamination.