EFFECT OF THERMAL SPRAY PROCESS SELECTION ON TRIBOLOGICAL PERFORMANCE OF WC–Co AND Al₂O₃–TiO₂ COATINGS

Abstract

High velocity oxyfuel (HVOF), air plasma spraying (APS), and low pressure plasma spraying (LPPS)techniques were used to deposit WC–Co and APS was used to deposit A1₂O₃–TiO₂ coatings on ASTM 4130 steel in a study of the effect of process selection on the friction and wear of the coatings under dry sliding conditions in air. The LPPS WC–Co, which had a cobalt matrix with few brittle η-carbides (CO₃w₃C and C0₆w₆C), small and evenly dispersed WC, and high residual compressive stress, was most abrasive to Al₂O₃–TiO₂.