Microstructure modification and enhanced high-temperature tribological properties of Stellite 12 matrix coatings via in-situ synthesized silicides assisted laser cladding

• Silicides modified Stellite 12 matrix coatings were fabricated by laser cladding. • 3.6–6.8 wt. % Si in-situ formed silicides and refined microstructure of coatings. • The coating with 5.2 wt. % silicon had the best self-lubrication. • The wear rate of modified coating was reduced by 1.46–7.08 times. The objective of this study is to reinforce the wear resistance of Stellite coatings over a broad temperature range. The microstructure and wear performance of Stellite 12 coatings were modified via in-situ synthesized silicides assisted laser cladding technology on the Inconel 718 alloy, and the chemical compositions of coatings were optimized to enhance the wear performance of coatings. Dry-sliding wear of coatings was evaluated via a ball-on-disk tester from room temperature to 1000 °C. The results suggested that in-situ formed W 3 Cr 12 Si 5 , CrSi, WSi 2 and SiC phases in coatings by addition of silicon, and the microstructure of coatings was refined. In-situ formed silicides greatly enhanced the hardness and wear performance of modified coatings. The wear rate of modified coatings was reduced by 1.46–7.08 times as compared with that of Stellite 12 coating, which was ascribed to the high microhardness, and the network structure of carbides and silicides as well as the antioxidation and the lubricity of SiO 2 . Considering the wear and friction, there was a threshold value of silicon content for the wear behavior of Stellite 12 coating at test conditions. This research provides a reference for improving the wear resistance of Stellite 12 as a protective coating of parts via laser cladding within a broad range of temperature.