Wear behavior of brazed WC/NiCrBSi(Co) composite coatings

Abstract

A metallurgically bonded composite coating of a Ni–Cr–B–Si alloy reinforced with cobalt-coated tungsten carbide (WC-Co) particles was produced on a carbon steel substrate by high temperature vacuum brazing. The bond strength of the coating/substrate interface and the tensile strength of the coating itself reached 300–360 and 100–140 MPa, respectively. Effects of Co and WC-17Co contents on the wear behavior of the coating have been systematically investigated at two different wear conditions, namely the high speed rotating slurry erosive wear and the wet sand/rubber wheel abrasive wear. Results show that the higher was the Co content in the coating, the lower were the hardness and wear resistance. In the slurry erosive wear, the WC reinforcement of the composite coating plays an important role protecting the matrix from being worn-out, whereas in the abrasive wear, the wear mechanism is mainly controlled by the scratching and micro-cutting of the matrix followed by the pull out of WC particles due to the scratching action of abrasives. The wear resistance of the brazed composite coating (WC/NiCrBSi(Co)) is better than that of the flame overlaid coating.