Wear and corrosion resistance of laser clad Ni2Si/NiSi composite coatings

Wear- and corrosion-resistant Ni2Si/NiSi composite coatings were fabricated on a substrate of 0.2% C carbon steel by laser-cladding using Ni–40 at.% Si elemental powder blends. Microstructure of the Ni2Si/NiSi composite coatings consists of plate-like Ni2Si primary phase and small amount of Ni2Si/NiSi eutectics in the inter-plate regions. Corrosion properties were evaluated using the anodic polarization and immersion corrosion methods in H2SO4 and NaCl water solutions. Wear resistance was tested under room-temperature block-on-wheel dry sliding wear test conditions. Because of the high hardness and abnormal temperature dependence and excellent corrosion-resisting properties inherent to the nickel silicides Ni2Si and NiSi, the laser clad/rapidly solidified Ni2Si/NiSi composite coatings have excellent chemical and electrochemical corrosion resistance and exhibit outstanding wear resistance and low friction coefficient under dry sliding wear test conditions.