Corrosive sliding wear behavior of laser clad Mo2Ni3Si/NiSi intermetallic coating

Many ternary metal silicides such as W2Ni3Si, Ti2Ni3Si and Mo2Ni3Si with the topologically closed-packed (TCP) hP12 MgZn2 type Laves phase crystal structure are expected to have outstanding wear and corrosion resistance due to their inherent high hardness and sluggish temperature dependence and strong atomic bonds. In this paper, Mo2Ni3Si/NiSi intermetallic coating was fabricated on substrate of an austenitic stainless steel AISI321 by laser cladding using Ni-Mo-Si elemental alloy powders. Microstructure of the coating was characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDS). Wear resistance of the coating is evaluated under corrosive sliding wear test condition. Influence of corrosion solutions on the wear resistance of the coating was studied and the wear mechanism was discussed based on observations of worn surface morphology. Results showed that the laser clad Mo2Ni3Si/NiSi composite coating have a fine microstructure of Mo2Ni3Si primary dendrites and the interdendritic Mo2Ni3Si/NiSi eutectics. The coating has excellent corrosive wear resistance compared with austenitic stainless steel AISI321 under acid, alkaline and saline corrosive environments.