Effect of Tungsten on Corrosion Resistance of Electroless Ni-W-P Coating

The effect of tungsten content on the corrosion resistance of as-plated and 700 ℃ heat-treated Ni-W-P deposits were investigated by electrochemical impendence spectroscopy(EIS), energy dispersive spectroscopy(EDS) and X-ray diffraction(XRD). The results showed that the corrosion resistance of as-plated coatings was determined by the amorphous degree. The corrosion resistance of heat-treated coatings was sharply improved and affected by the compactness of tungsten oxidation formed during the heat-treatment.