Microstructure and tribological performance of WC-Co cermet strengthened nickel alloy composite coatings manufactured by extreme high-speed laser cladding (EHLA)

Composite coatings composed of blended nickel alloy (IN625) and WC-Co cermet were applied via the extreme high-speed laser cladding (EHLA) process to investigate its feasibility as a coating replacement for hard chrome plating. A range of laser powers was investigated. These cermet coatings were benchmarked against an IN625-only coating, in the analysis of their macrostructure, microstructure, phase composition, Vickers microhardness and sliding wear resistance by the pin-on-disc test. The EHLA process resulted in crack-free coatings, with a good metallurgical bonding to the substrate and homogenous distribution of cermet particles within the coatings. The microhardness of the EHLA composite coatings increased by 81–102 % as compared to the IN625 EHLA coating. The wear rates of the composite coatings were only 0.5–1.4 % that of the IN625 coating, and only 1–4 % that of hard chrome coating. A decrease in laser power demonstrated an increase in the carbide-occupied cross-sectional area from 11.2 % to 17.2 %, which corresponded to a 64 % enhancement in wear resistance. This study highlights the critical balance required between laser power, carbide area fraction and microstructural characteristics, on the performance of EHLA-deposited composite coatings. • Crack-free composite coatings achieved at improved efficiency with high-speed EHLA. • Dense EHLA coatings of nickel alloy and WC-Co show good substrate bonding. • Coatings show better wear resistance than base nickel alloy and hard chrome. • Rapid solidification from EHLA results in homogeneous cermet distribution. • Lower laser power reduces dilution of carbides and enhances wear resistance.