Zn-Ni-Cd alloy was electroplated from an alkaline sulfate bath under potentiostatic conditions. The corrosion and hydrogen permeation characteristics of Zn-Ni-Cd alloy coatings electrodeposited from alkaline bath were studied and compared with those of Cd and Zn-Ni coatings obtained using commercial baths. Zn-Ni-Cd alloy was electroplated from an alkaline sulfate bath under potentiostatic conditions. The corrosion potential of this Zn-Ni-Cd coating was -0.62 V vs. SCE, which is still negative potential compared to iron. The corrosion rate of Zn-Ni-Cd coated steel was 0.073 mm y-1, which is estimated in a 0.5 M Na2SO4 + 0.5 M H3BO3 solution at a pH of 7. This value is much lower than the corrosion rate of Zn-Ni alloy (0.502 mm y-1) and Cd (0.306 mm y-1) coatings deposited from commercial baths. Zn-Ni-Cd alloys are also demonstrated to have superior hydrogen permeation inhibition properties compared to Cd and Zn-Ni coatings. Kinetic parameters of hydrogen permeation such as the transfer coefficient, α, the modified exchange current density, i′0, thickness dependent adsorption-absorption rate constant, k″, recombination rate constant, k3, surface hydrogen coverage, θs, were evaluated by applying a mathematical model to analyze experimental results.
Bibliographical noteFunding Information:
Financial Support by Dr. Vinod Agarvala, the Office of Naval Research under Grant no. N00014-00-1-0053 and AESF Research Contract, Project 107 are gratefully acknowledged. This work was also partially supported by Sandia National Laboratories. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94-AL85000.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Materials Science(all)