The Wear and Corrosion Behaviors of Fe-Based Coating Fabricated by High-Speed Laser Cladding for Hydraulic Support Column Application

Abstract

In this study, the tribological and corrosion properties of multilayer Fe-based coating fabricated on the hydraulic support column (27SiMn steel substrate) by high-laser speed cladding (HLC) were investigated. The phase structural, microstructural observation and hardness distribution of the Fe-based coating were analyzed, and its electrochemical properties after the immersion test and the corrosion performance in the field service environment were adopted to probe the corrosion resistance of Fe-based coating. The results show that the eight-layer Fe-based coating forms around 1.59 μm equiaxed crystal structure with a single BCC phase, and the hardness increases by 39.8% compared to the substrate. The coating exhibits a higher wear resistance with a wear rate of 3.34×10-4 mm3·(N·m)-1, which is 82.5% lower than that of the substrate. The corrosion rate of the coating is far lower than that of the substrate, even at immersion for 45 days, the corrosion resistance of the coating remains higher than that of the substrate at immersion for 15 days. Based on the electrochemical and Mott-Schottky measurements, the corrosion resistance of coating presents a downward trend with the immersion time prolonged, which is related to the increased defect density and inhomogeneity of oxide films formed on the coating surface, increasing the susceptibility of corrosion pitting. After 300 days in the mine environment, the corrosion rate of coating is 1.73 mm/a, which is only 8% of that of substrate, proving that the protective coating can significantly improve the service life of the substrate.

Keywords: High-speed laser cladding, Fe-based coating, friction-wear mechanism, immersion corrosion mechanism, electrochemical corrosion behavior