Tribological Properties of Plasma-Sprayed Coatings Under Water-Lubricated Sliding

Tribological properties of plasma-sprayed self-mated Cr3C2-NiCr, WC-Co and Cr2O3 coatings and the Cr2O3 coating against WC+Co hard alloy and toughened SiC ceramics were investigated under water-lubricated sliding. It was found that Cr2O3 coating was the most wear-resistant among the three kinds of self-mated coatings and had a wear coefficient less than 10-6mm3N-1m-1. Wear mechanisms of the coatings were explained in terms of microcracking and grain fracturing. The higher the fracture toughness, and the lower the porosity and the length of microcrack of the coating, the more wear-resistant the coating was. The friction coefficient and wear coefficient of Cr2O3 coating were obviously reduced when it was mated to WC+Co hard alloy and toughened SiC ceramics, which may be related to surface condition and tribochemical reaction of material of friction pair.