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.