Oxidation-dominated wear behaviors of carbide-based cermets: A comparison between WC-WB-Co and Cr3C3-NiCr coatings

A WC-40WB-12Co coating has been developed and demonstrated to have comparable oxidation resistance, remarkably enhanced hardness (over 2 times higher) and improved wear resistance (2-4 times higher) than the widely used Cr3C2-25NiCr coating at elevated temperatures. Wear failure of Cr3C2-NiCr coating was dominated by severe subsurface cracking due to oxidation and its poor high-temperature mechanical properties. By contrast, in the WC-WB-Co coating, the thin oxide scale formed on the surface increased lubrication and hindered further oxidation. The WC-WB-Co coating provided strong mechanical support for the oxide layer. The coating thereby achieved an outstanding high-temperature wear performance. Based on detailed comparisons, the wear mechanisms of these carbide-based cermet coatings at elevated temperatures were proposed.