Corrosion resistance of Zn-Co alloy coatings
1994; Elsevier BV; Volume: 63; Issue: 1-2 Linguagem: Inglês
10.1016/s0257-8972(05)80013-1
ISSN1879-3347
AutoresR. Fratesi, G. Roventi, C. Branca, S. Simoncini,
Tópico(s)Concrete Corrosion and Durability
ResumoThe corrosion behaviour of commercial zinc and Zn-Co alloy coatings, with and without chromate conversion treatment, was studied by means of salt spray tests and electrochemical tests in aerated 0.6 M NaCl solution at various pH values. At almost neutral pH values, the chromated Zn-Co coatings show a better corrosion resistance than that for conventional chromated zinc coatings, as a result of a particularly protective chromate conversion layer which increases both the cathodic and anodic overvoltages. At lower pH values, the corrosion resistance of both chromated zinc and chromated Zn-Co alloy decreases. This is attributed to the depolarization of the cathodic reaction (hydrogen reduction) and to the quick destruction of the chromate layer.
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