Effect of Porosity and Laminar Structure on Erosion Resistance of WC-Co-Cr Coatings

Three different HVOF/HVAF spray devices and six kinds of commercial powders were used to prepare specimens of WC-Co-Cr coatings with different microstructure on 0Cr13Ni5Mo stainless steel substrate. Their erosion behaviors were investigated on a self-manufactured slurry pot erosion tester. The effects of porosity and laminar structure on erosion resistance of coatings were researched. The result shows that the poor erosion resistance was due to their porosity and laminar structure. In low velocity and concentration slurry, the effect of porosity on erosion resistance of coatings was more pronouced than that of laminar structure. The erosion resistance of high porosity coatings was even worse than that of substrate. In high velocity and concentration slurry, the coatings with laminar structure showed the worst erosion resistance. The validity of characterization about laminar structure of coating by specific energy consumption (SEC) in single pendulum impact scratch testing was explored. Moreover, the possibility of deduction about the erosive resistance from the porosity and SEC of coating was discussed.