FRICTION AND WEAR BEHAVIOR OF A NUMBER OF CERAMIC-COATED STEELS MATCHED AS SLIDING PAIRS TO VARIOUS SURFACE-TREATED STEELS

Ceramic-coated steels (WC + 12%Co and Cr3C2 + 25%NiCr applied by continuous detonation spraying, and Cr2O3 applied by plasma spraying) were mated as sliding pairs to surface-treated steels (case hardened, tufftrided) under both dry wear and lubricated conditions in order to assess their tribological potential. Under dry wear conditions, WC-Co demonstrates the lowest coefficient of friction but surface-treated steels paired with Cr3C2-NiCr possess the best wear resistance under both dry wear and lubricated conditions. Five different types of generalized friction behavior were identified among the pairs studied. Under dry wear conditions, the worn surface of Cr3C2-NiCr is covered with continuous and ''island''-transferred layers, while that of Cr2O3 exhibits numerous cracks. The worn surface of WC-CO can be divided into four distinct regions, each possessing a major wear characteristic in addition to that of surface polishing. Wear mechanisms for TF1 surface-treated steels include surface polishing, strain fatigue and fracture of the work-hardened layer, while those for carburized steel include surface polishing, plastic deformation, material transfer and pile-up of back-transferred material. Under lubricated conditions, the amount of material transferred is reduced.