It is shown that an electrodeposited Zn-Ni-Cd alloy coating produced from sulfate electrolyte inhibits the discharge of hydrogen on carbon steel. The newly developed ternary alloys have approximately ten times higher corrosion resistance when compared to a Zn-Ni alloy. Hydrogen permeation characteristics of Zn-Ni-Cd alloy coatings were studied and compared with those of a bare and a Zn-Ni alloy coated steel. The transfer coefficient, a, exchange current density, io, thickness dependent adsorption-absorption rate constant, k0, recombination rate constant, k3, surface hydrogen coverage, θH, were obtained by applying a mathematical model to experimental results. Alloys obtained from baths containing higher concentration than 3 g/L of CdSO4 in the sulfate plating bath are seen to have superior permeation inhibition properties compared to the Zn-Ni alloy coating and bare steel. The hydrogen permeation current was zero under normal corroding conditions for Zn-Ni-Cd alloy and it increased to 0.3 mA/cm2 at a cathodic overpotential of 250 mV. The hydrogen permeation current density for steel and Zn-Ni alloy under similar conditions were 62.1 and 1.3 mA/cm2, respectively.
Journal of the Electrochemical Society, 2000, pages 4507-4511.
© The Electrochemical Society, Inc. 2000. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS). The archival version of this work was published in the Journal of the Electrochemical Society.
Publisher's link: http://dx.doi.org/10.1149/1.1394093