Microstructure and corrosion resistance of Ni-based alloy coating by plasma cladding on 316L stainless steel

A wear-resistant and corrosion-resistant coating was prepared by plasma cladding on 316L stainless steel with Ni-based alloy powder.The microstructure of the coating was investigated by optical microscope(OM),scanning electron microscopy(SEM) with energy dispersive spectroscopy(EDS),X-Ray diffractometer(XRD).The microhardness of the coating was tested by microhardness tester.The corrosion resistance of the coating in 3.5% NaCl solution was evaluated by linear polarization.The results showed that the microstructure of the coating consisted of dendritic γ-(Ni,Fe) solid solution and Cr₂₃C₆.The microhardness of the coating varied from 400 HV0.2 to 440 HV0.2,greater than that of the substrate(170~200 HV0.2).The corrosion potential of the coating in 3.5% NaCl solution moved reversely 178 mV,the breakdown potential(0.1 V) of the substrate was higher than that of coating(-0.1 V),which demonstrated the corrosion resistance of the substrate was better than coating.