This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Corrosion Mechanism of Zn-Ni Alloy Electrodeposited Coatings
Annotation ability available
Sector:
Language:
English
Abstract
Electrodeposited Zn-Ni alloy coatings show a maximum resistance to salt spray corrosion at 12% to 15% Ni. To gain an increased understanding of this behavior, we studied the corrosion mechanisms of 13% Ni coatings in sodium chloride solutions with electrochemical, microscopic, x-ray, and Auger electron spectroscopic methods. We observed that the Zn-Ni alloy initially corrodes with the preferential dissolution of zinc. As the coating dezincifies, tensile stresses are created in the coating causing development of a fine network of cracks. As corrosion progresses, the coating transforms into a composite barrier layer consisting of a micro cracked nickel-rich metallic phase and zinc corrosion products. This behavior contrasts with that of pure zinc coatings which corrode by a simple mechanism of uniform dissolution. The superiority of Zn-Ni alloy coatings in salt spray corrosion appears to result from slower anodic dissolution kinetics and some barrier protection afforded by the remaining composite layer.
Recommended Content
Authors
Topic
Citation
Lambert, M., Hart, R., and Townsend, H., "Corrosion Mechanism of Zn-Ni Alloy Electrodeposited Coatings," SAE Technical Paper 831817, 1983, https://doi.org/10.4271/831817.Also In
References
- Baboian, R. Automotive Corrosion by Deicing Salts National Association of Corrosion Engineers Houston 1981
- VandeWalle, L. J. Efficient Materials and Coatings Applications for Improved Design and Corrosion Resistance American Society for Metals Metals Park, Ohio 1981
- Cracking Down on Corrosion, Publication No. SG 731-1078-20M-SP American Iron and Steel Institute Washington, DC 1978
- King, J. H. Automotive Corrosion Protection in the 1980’s Abstract No. 51, Extended Abstracts of the Fall Meeting October 17-21 1982 The Electrochemical Society Pennington, New Jersey 1982
- Shibuya, A. Kurimoto, T. Korekawa, K. Noti, K. Tetsu-To-Hagane 66 7 771 778 1980
- Hilley, M. E. Residual Stress Measurement by X-ray Diffraction-SAE J784a Society of Automotive Engineers, Inc. New York, New York 1971
- Chang, Y. A. Metallography, Structures, and Phase Diagrams, Metals Handbook 8 Eighth Edition American Society for Metals Metals Park, Ohio 1973 326
- Kitazawa, Y. Electro-Alloy-Coated Steel Sheets Developed by Nippon Steel for the Auto Body Paper No. 8201-034 presented at the 1982 ASM Metals Congress American Society for Metals Metals Park, Ohio 1982
- Siitari, D. Sagiyama, M. Hara, T. Corrosion of Electrodeposited Ni/Zn Alloy: Electrochemical and Morphology Studies Tetsu-To-Hagane 68 5 130 1982
- Pourbaix, M. Atlas of Electrochemical Equilibria in Aqueous Solutions Pergamon Press London 1966 333 406