EROSION RESISTANT COATING BY LOW-PRESSURE PLASMA SPRAYING

Cavitation erosion and drain erosion are major causes of failure of me chanical devices in fluid handling systems. The authors investigated t he application of plasma spraying technique to the formation of coatin gs with high resistance against the cavitation and drain erosion damag e. By using low pressure plasma spraying, some coatings of cermet and metallic alloy materials were prepared and tested for the cavitation e rosion behavior. Cobalt base alloy coating shows much more excellent r esistance to the erosion than that of Stellite-6, which has been widel y used as the wrought product to shield a steam turbine blade from the damage. In spite of the similar chemical composition of the Co alloy to that of Stellite-6, the erosion-performance is different. Microscop ic characterization of the deposite reveals that the superiority of th e coating is caused by the extended solid solubility of carbon resulte d from the rapid solidification of the sprayed droplets.