Fabrication and characterisation of functionally graded Ni-P coatings with improved wear and corrosion resistance

摘要

In this study, the functionally graded Ni-P coatings with low phosphorus top most layers were deposited on the copper substrates by the electroless plating process. The surface morphology and cross-section observations were made by using scanning electron microscopy and optical microscopy. The results showed that electroless deposition of the Ni-P coatings with gradual change of phosphorus content led to a crack-free compact nodular morphology. Also, by using the graded Ni-P coatings, the wear and corrosion resistance were improved. The multilayer coating with the sequence of Ni-high P/Ni-medium P/Ni-low P layers from the substrate to the top surface exhibited the best wear and corrosion resistance.