Study on Electroless Plating Ni-W-P Ternary Alloy with High Tungsten from Compound Complexant Bath

The Ni-W-P alloy coatings have been widely used in the fields of electronic, aviation and anticorrosion, owing to their high hardness, good wear resistance and strong corrosion resistance. Herein, we study the effects of complexants on the chemical composition, morphology and plating rate of the Ni-W-P ternary alloy coatings by developing a near-neutral plating solution with disodium edetate, sodium citrate and lactic acid as complex complexants. The results of scanning electron microscope (SEM) and energy-dispersive spectrometer (EDS) indicate that a flat and dense coating with the W content up to 11.75 wt.% is acquired by adjusting the composition of plating solution. Meanwhile, the plating rate of Ni-W-P coating can reach up to 22.4 µm/h. Furthermore, the characterization results indicate that the Ni-W-P ternary alloy coating possesses higher hardness, better wear and corrosion resistance compared to Ni-P coating. These findings may exploit a broader field for searching better complexants in electroless coating and for understanding the related mechanisms to provide guidance for the design of ternary alloy coatings.