Anodizing of Magnesium Alloys

The presence of iron in magnesium alloys pose problems by reducing the corrosion resistance of magnesium alloys. Mg-1%Fe alloy was deposited onto an aluminium substrate by magnetron sputtering. The sputtered mg-Fe alloy was anodised to voltages of 25, 50 and 100 V, at a constant current density of 15mA/cm2 in 0.05 M KOH + 0.25 M Na2SiO3 electrolyte with pH ~12, at room temperature of ~20 0C. The Voltage-time tracer was used to study the anodising process. The sputtered Mg-1%Fe alloy and anodic film formed on the alloy were studied using some techniques such as the SEM, EDX, GDOES, AFM and XRD analyses were employed to identify the structure, morphology and composition. For anodic films grown at 25 and 50 V there were no holes found in the anodic films. Holes were found at the bottom the anodic film of the specimen anodised to 100 V. The possibility of Fe enrichment in Mg alloy by growth of anodic films was studied. With the results presented there was insufficient evidence to show that there was Fe enrichment just below the anodic film.