The corrosion behavior of coated materials after painting were investigated in cyclic corrosion tests and outdoor exposing tests. The coatings of pure Zn, Zn-Fe alloy, Zn-Ni alloy, and Zn-Co-Cr alloy with dispersed particles of Al2O3 were submitted to the tests. Several cyclic corrosion tests whose time ratio of wet environments in a cycle were different from each other were conducted. The outdoor exposing tests were also carried out at the seashores in both Okinawa and Chiba, Japan. The samples were sprayed with seawater twice a week in the test at Chiba to accelerate corrosion. Corrosion properties of samples were estimated by the blistering width at the knife-cut. In a cyclic corrosion test which contains less than 40 % of wet environment in a cycle the coated materials were proved to have an excellent anti-blistering property comparing with cold rolled steel sheet. The results of the two outdoor exposing test proved that the coated materials more than 30 g/m2 of Zn and Zn-alloy have satisfactory anti corrosion property after painting but that the decrease in coating weight to 20 g/m2 makes the property unstable independantly of the kind of coating. Among the tested materials, the Zn-Co-Cr alloy containing dispersed particles of Al2O3 showed the highest resistance for blistering.
Cosmetic corrosion of Zn alloy coated sheet steels
Kosmetische Korrosion von mit Zinklegierung beschichteten Stahlblechen
1988
7 Seiten, 9 Bilder, 4 Tabellen, 10 Quellen
Aufsatz (Konferenz)
Englisch
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