Microstructure and slurry erosion-wear behaviors of high-speed laser cladding Stellite6/60 %WC composite coatings

Erosion-wear is one of the principal failure forms for the underwater components. To improve the erosion-wear resistance, cladding Stellite6/WC composite coatings has been regarded as a suitable method. However, it has always been a bottleneck problem to prepare Stellite6/WC composite coatings with high (≥60 wt%) WC content by laser cladding, which significantly limits their applications and the understanding of erosion-wear behaviors. In this work, Stellite6/WC composite coatings with WC content varying from 0 to 60 wt% have been fabricated using high-speed laser cladding. Furthermore, the effects of WC addition on the microstructure and erosion-wear behaviors in NaCl solution-SiO₂ slurry have been systematically investigated. The results show that the dissolution of WC is slight during the high-speed laser cladding process, and metallic carbides form in the surrounding regions. The addition of WC can refine the microstructure of the Stellite6 matrix as well as induce solid solution strengthening. The hardness of the 60WC coating was significantly increased to 1170.78 HV₅, attributed to the enhanced presence of the WC hard phase. The erosion-wear resistance increases with the addition of WC, and 60WC coating shows the lowest erosion-wear volume loss, with a decrement of 95.19 %. Although WC can hinder scratching and ploughing by SiO₂ abrasive, the fracture and spalling caused by abrasive impact play a negative role in the erosion-wear resistance. On the other hand, WC particles can inhibit damage to the surrounding regions, exhibiting a “shadow-protective” effect. Synergistic protection occurs among WC particles in the 60WC coating, contributing to reducing the fracture and spalling of WC.