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Chromate-Free Pre-Treatment for Zinc and Galvanized Steel
CCHV/M-10

Authors

Aranka Pilbath - Chemical Research Centre of the Hungarian Academy of Sciences, Department of Surface Modification and Nanostructures
Franciska H. Karman - Chemical Research Centre of the Hungarian Academy of Sciences, Department of Surface Modification and Nanostructures
Ilona Felhosi - Chemical Research Centre of the Hungarian Academy of Sciences, Department of Surface Modification and Nanostructures
Judit Telegdi - Chemical Research Centre of the Hungarian Academy of Sciences, Department of Surface Modification and Nanostructures
Erika Kalman - Chemical Research Centre of the Hungarian Academy of Sciences, Department of Surface Modification and Nanostructures

Abstract

ABSTRACT

Zinc and zinc coated products corrode in ambient air and in the presence of water rapidly, producing a white corrosion product – named as white rust. Chromate conversion coatings provide very effective corrosion protection against white rust. Due to the toxic and carcinogenic properties of Cr6+ ion, the corrosion protection with chromating technique needs replacement. The objective of our studies was to protect zinc surface against corrosion, with a thin phosphonate layer. For surface pre-treatment, aqueous solutions of diphosphonic acid with different alkyl-chain length were applied with different treatment times. The spontaneously formed 1,5-diphosphono-pentane layer on zinc surface has protective effect in corrosive environment.

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