Abstract: A corrosion resistant Ni-Si silicides composite coating is fabricated on substrate of a low carbon steel A3 by laser cladding using the Ni, Si, Cr powders. The laser clad silicides composite coating, which is metallurgically bonded to the steel substrate, has a rapidly solidified microstructure consisting of cellular dendritic Ni2Si primary phase and small amount of interdendritic FeNi/Ni31Si12 eutectics. The average microhardness of the laser clad silicide alloy coating ranges from HV800 to HV950. The corrosion resistances of the silicides composite coating in the water solutions of 0.5 mol/L H2SO4 and 3.5% NaCl were evaluated utilizing the anodic polarization electrochemical corrosion test method. Because of the inherent excellent corrosion resisting properties of the constituting phases of Ni2Si and Ni31Si12 , and the rapidly solidified homogeneous microstructure, the laser clad nickel silicides composite coating exhibits excellent corrosion resistance.
Microstructure and corrosion resistance of laser clad Ni-Si silicides composite coating
Abstract:
A corrosion resistant Ni Si silicides composite coating is fabricated on substrate of a low carbon steel A3 by laser cladding using the Ni, Si, Cr powders. The laser clad silicides composite coating, which is metallurgically bonded to the steel substrate, has a rapidly solidified microstructure consisting of cellular dendritic Ni 2Si primary phase and small amount of interdendritic FeNi/Ni 31 Si 12 eutectics. The average microhardness of the laser clad silicide alloy coating ranges from HV800 to HV950. The corrosion resistances of the silicides composite coating in the water solutions of 0.5?mol/L H 2SO 4 and 3.5% NaCl were evaluated utilizing the anodic polarization electrochemical corrosion test method. Because of the inherent excellent corrosion resisting properties of the constituting phases of Ni 2Si and Ni 31 Si 12 , and the rapidly solidified homogeneous microstructure, the laser clad nickel silicides composite coating exhibits excellent corrosion resistance.
Fig.2 Liquidus projection of Fe-Ni-Si ternary alloy system showing sampling location of chemical composition analysis of laser clad Ni-Si silicides composite coating
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Fig.3 OM photograph showing transverse cross-section microstructure of laser clad Ni-Si silicides composite coating (a) and SEM photograph showing metallurgical bonding to substrate (b)
图4 激光熔覆Ni-Si金属硅化物复合材料涂层典型组织照片
Fig.4 SEM micrographs showing typical microstructures of laser clad Ni-Si silicides composite coating