Preparation of high wear resistance nickel based WC coating by carefully adjusting interface structure

Abstract

In recent years, many scholars have paid attention to wear-resistant coatings for shield machine cutterheads due to their very high consumption rates. Among these coatings, nickel-based tungsten carbide (Ni-based WC) is one of the best, showing both corrosion resistance and wear resistance. However, to further improve the wear resistance of such coatings, there are still numerous issues that need to be resolved. Herein, a new method, distinct from conventional methods, is presented. Specifically, the brittle phase W2C is not widely regarded as the main wear-resistant phase, but we were surprised to find that careful adjustment of its rigid structure can yield satisfactory results. Experimental results and first-principles simulations have indicated that the friction coefficient and weight loss of a coating with a suitable distribution of W2C are only half of those of a traditional Ni-based WC coating (about five times higher than those of the substrate), which can mainly be attributed to the excellent thermal expansion coefficient and hardness of the W2C phase. As we expected, the surface morphology of the material after wear revealed that the suitable W2C layer has a well-defined friction morphology. We hope to provide new ideas for the study of Ni-based WC coatings in shield machine cutterheads.