Wear-Resistant WC Composite Hard Coatings by Brazing

A wear-resistant tungsten carbide/copper (WC/Cu) brazing alloy coating was deposited onto a steel substrate by high-temperature furnace brazing. Compared with other hard surfacing processes, much larger WC particles could be used to make a metal layer with higher wear resistance. ASTM G-65 wear test results for the brazed composite coating showed a higher wear resistance when compared with some WC-Co hard coatings that are commonly used. In this paper, the brazing alloy, the brazing process, and the after-brazing heat treatment are studied. The microstructure of the brazing alloy and the as-deposited coating were characterized, and no significant porosity was found. A good metallurgical bond was formed at the WC/Cu alloy interface and at the composite coating/substrate interface. Little or no dilution was observed. The bond strength between the Cu alloy and substrate is also much higher than for a thermal spray coating.