Electrodeposition of Re–Ni–W Ternary Alloy from EDDS Solution

Re–Ni–W coatings were electrodeposited from an ethylenediamine-N,N′-disuccinic acid (EDDS)-based aqueous electrolyte, and the effects of EDDS concentration, ReO 4 − /WO 4 2− supply, anode type, NiSO 4 concentration, and deposition time on alloy composition, growth behavior, morphology, structure, and corrosion resistance were investigated. EDDS concentration strongly affected both coating growth and the relative incorporation of Re and W. Low EDDS concentrations produced Re-rich deposits containing 50.3–50.6 wt.% Re, whereas higher EDDS concentration promoted W incorporation up to 14.5 wt.% but reduced the deposited amount. ReO 4 − and WO 4 2− concentrations showed opposite effects on relative incorporation of Re and W, indicating a competitive relationship between these two refractory elements. Compared with Ni plate anode, Ti mesh anode favored higher total refractory-element contents under the investigated conditions. In Ti mesh system, 34 mM NiSO 4 gave the highest total Re + W content of 75.6 wt.%. The deposition conditions affected surface morphology, local crack formation, and coating buildup, while the alloy coatings exhibited nanocrystalline or amorphous-like structures. Re 29.5 Ni 53.6 W 16.9 coating in 3.5 wt.% NaCl solution exhibited the good corrosion resistance with the lowest i corr value of 3.39×10 −6 A·cm −2 and the highest R p and R ct values of 8394 Ω·cm 2 and 5693 Ω·cm 2 , respectively.