Stannate and permanganate conversion coatings on AZ31 magnesium alloy
2007; Elsevier BV; Volume: 49; Issue: 12 Linguagem: Inglês
10.1016/j.corsci.2007.04.011
ISSN1879-0496
AutoresF. Zucchi, A. Frignani, V. Grassi, G. Trabanelli, C. Monticelli,
Tópico(s)Aluminum Alloys Composites Properties
ResumoThe formation of stannate and permanganate–phosphate conversion coatings on AZ31 magnesium alloy was investigated in situ by EIS measurements and their protective performances were studied by different electrochemical techniques in diluted (0.05 M) sodium sulphate solution. The influence that short or long treatment times exert on the performances of such conversion coatings is discussed. While permanganate–phosphate baths always built layers characterized by penetrating cracks, long stannate baths produced layers without interconnected porosity, but were defective. This accounted for the initial greater protectiveness achieved with the stannate treatment; nevertheless, the easy penetration of the electrolytic solution through such a layer quickly decreased its corrosion resistance.
Referência(s)