Wear Resistance of Fe-Based Amorphous Powder Deposited Coatings in Air, Water, and SBF Solution: Effect of Layer Number

Abstract

Amorphous alloys have high strength and high hardness, showing their potential applications as tribological materials. In order to improve the wear resistance of 316L stainless steel (SS), Fe-based amorphous powder was deposited on 316L SS by laser cladding. Since the microstructure of the laser clad coating was sensitive to the dilution between coating and substrate, multilayer Fe-based metallic coatings were fabricated layer by layer. When the laser cladding layer number increased, the microstructure evolved from a complete crystalline phase to a mixed structure with amorphous phase and dendrite. Meanwhile, the amorphous content increased and the average microhardness was enhanced. Accordingly, the wear resistance was improved generally under all the sliding conditions, including in air, distilled water, and simulated body fluid (SBF) solution. For the lubricant effect of liquid, the coefficients of friction in distilled water and SBF solution are relatively lower than that in air. Compared with 316L SS, the volume loss rate of nine-layer coating decreased by two orders of magnitude in air and about 5.5 times in SBF solution. Except for one-layer coating, the predominant wear mechanism of the laser clad coatings in air is abrasive wear accompanied by oxidative wear. The wear mechanism in SBF solution is dominated by abrasive wear and corrosive wear. The superior hardness and good corrosion resistance are responsible for the outstanding wear resistance improvement. Therefore, the laser clad coating with Fe-based amorphous alloy has a potential application in the surface strengthening of mechanical parts or metallic implants.