Wear behavior of laser cladded WC-reinforced Ni-based coatings under low temperature

Abstract

In this paper, three groups of spherical WC-reinforced Ni-based coatings were fabricated by laser cladding on EH40 steel. The microstructure, microhardness and wear mechanism of Ni-WC composite coatings at low temperatures (20 °C, 0 °C and −20 °C) were studied systematically. The effect of temperature change on friction properties of Ni-WC coatings was analyzed. The results showed that the microstructure of the coating is mainly composed of M23C6 hard phase, Cr2Ni3 compound and γ-Ni solid solution. The coating's hardness gradually increased as the WC content increased. It turns out that Ni+ 15%WC shows excellent wear resistance at −20 °C, having the minimum wear volume and lowest wear rate, which are 0.0159 mm3 and 6.36 × 10−5 mm3/N.m−1, respectively. The existence of WC and hard phase reduces the plastic deformation caused by the friction ball and the coating surface, and adhesive wear dominates the wear mechanism. As the temperature dropped from room temperature to low temperature, the wear mechanism transforms from adhesive wear to abrasive wear. Compared to those at 20 ℃ room temperature, the coefficients of friction, wear volume and wear rate all increase at low temperatures.