Bare magnesium is not compatible with the zinc phosphate process commonly used in automotive manufacturing today. If a magnesium component is assembled onto the vehicle prior to the phosphate process, it must be coated beforehand to prevent magnesium dissolution in the phosphate bath. In addition, for a component that must function in very corrosive environments, galvanic corrosion problems also need to be addressed because the component is most likely to be connected with a more noble metal such as steel fasteners or to another component made of steel or aluminum. In this paper, several coatings were evaluated for their effectiveness in stopping magnesium dissolution during phophate process and preventing galvanic corrosion. The results show that a porous anodized or a very thin chemical conversion coating does not completely stop magnesium dissolution during the phosphate process. An epoxy E-coat stops magnesium dissolution during the phosphate process but is not very effective in preventing galvanic corrosion. An epoxy powder coat or a properly sealed anodized film notonly prevents magnesium dissolution in the phophate bath but also provides good glavnaic corrosion protection.


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    Title :

    Evaluation of protective coatings on magnesium for phosphate process compability and galvanic corrosion prevention


    Additional title:

    Bewertung von Beschichtungen für Magnesium für die Phosphatverträglichkeit und Verhinderung von galvanischer Korrosion


    Contributors:
    Gao, G. (author) / Ricketts, M. (author)


    Publication date :

    2002


    Size :

    7 Seiten, 6 Bilder, 3 Tabellen, 6 Quellen




    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English






    2002-01-0081 Evaluation of Protective Coatings on Magnesium for Phosphate Process Compatibility and Galvanic Corrosion Prevention

    Gao, G. / Ricketts, M. / Society of Automotive Engineers | British Library Conference Proceedings | 2002


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    Galvanic Corrosion Prevention of Steel-Aluminum Couples

    Doyle, D. P. / Courval, G. J. / Allin, J. | SAE Technical Papers | 1993