代替クロムめっき用無電解Ni-W-P合金めっき膜の作製

抄録

An environmentally friendly chromium-free Ni-W-P alloy plating was prepared as an alternative to hard chrome plating by electroless plating. The alloy plating film, which was electroless plated in an alloy plating bath containing 0.22 M Na₂WO₄, contained 16 mass% W. The alloy plating film calcined at 600 °C had a NiO layer (0.5 μm), a Ni-W-P layer (10.8 μm), and a Ni layer (1.0 μm) from the surface. The Vickers hardness of the plating film calcined was over 1000 Hv. Ni-W solid solution crystals and Ni₃P crystals were formed in this hard plating film. The corrosion potential of the alloy plating film was found to be 0.32 V greater than that of the nickel plate, which indicates a potential for improvement in corrosion resistance.