Constant Magnetic Field Refinement of Chromium-free Conversion Coatings on AZ31 Magnesium Alloy
G. Bikulcius, A. Rucinskiene, E, Sudavicius, and A. Selskis
Institute of Chemistry, ul. Goshtauto 9, Vilnius, 01018 Lithuania
Received October 02, 2007
Abstract—By the electrochemical protective efficiency of conversion coatings on an AZ31 alloy, it is shown that the corrosion stability of AZ31 alloy depends on the activating solution treated with magnetic field. Scanning electron microscopic studies demonstrate that the surface morphology of conversion coatings is identical irrespective of the magnetic field treatment. The cross-section composition of conversion coatings is deter-mined by x-ray photoelectron spectroscopy (XPS). XPS data demonstrate that a conversion coating treated with magnetic field is thicker than coatings nonsubjected to this treatment. It is also shown that a conversion coating of AZ31 alloy mainly consists of oxides and hydroxides, namely, MgO, Mg(OH)2, MgF2 and 
Al2O3, MgAl2O4. However, when magnetic field is applied, the aluminum concentration increases from 0.73 to 6.65 at. %, and the fluorine concentration decreases from 12.06 to 8.11 at. %.
Al2O3, MgAl2O4. However, when magnetic field is applied, the aluminum concentration increases from 0.73 to 6.65 at. %, and the fluorine concentration decreases from 12.06 to 8.11 at. %.
PACS numbers: 81.65.Kn
DOI: 10.1134/S2070205109020178