Investigation on the Ni60-WC composite coatings deposited by extreme-high-speed laser-induction hybrid cladding technology: Forming characteristics, microstructure and wear behaviors

In this work, Ni60-WC composite coatings with 35 wt% WC (Ni65-WC35), 50 wt% WC (Ni50-WC50) and 65 wt% WC (Ni35-WC65) were deposited by the extreme-high-speed laser-induction hybrid laser cladding technology (EH-LIHC), and the forming characteristics, microstructure, hardness and wear behaviors were investigated systematically. Results indicated that all the EH-LIHCed Ni60-WC coatings displayed low-roughness surfaces and even-distributed WC particles, where the dilution ratio and WC's heat-loss increased with the rise of induction heating temperature (T) and WC's content. Crack-free single-layer Ni60-WC coatings could be obtained at T ≥ 600 °C, whereas some micro-cracks were inevitably induced during the multi-layer depositions. The WC particles mainly presented the decomposition/ dissolution-diffusion, collapse-dissolution and decomposition/dissolution-precipitation heat damages, corresponding to the W-rich dendritic/wing-like/filamentary structures, dendritic facet structures and blocky facet structures on the metal matrix, respectively. Under both loading forces of F = 50 N and 80 N, the wear rates Ni60-WC composite coatings presented the order of Ni35-WC65 < Ni65-WC35 < Ni50-WC50. Spalling of the matrix, cracking and crushing of the WC particles were detected on all worn surfaces. The Ni35-WC65 coating possessed the highest contents of WC particles and facet carbides, making its damage threshold and wear resistance enhanced significantly. Nonetheless, the wear debris in Ni65-WC35 coating had formed a metal layer covering on the worn surface, helping to alleviate the damage of the beneath WC particles significantly, therefore it possessed lower wear rate than that of Ni50-WC50 coating.