Abstract
Effect of anodizing film thickness (12-60μm) and sealing time (120-900s) on corrosion behavior of anodized diecast magnesium alloy AZ91D-F has been investigated by salt spray test (SST). X-ray diffraction, EDX and ESCA showed that anodizing film consisted mainly of Cr2O3, MgF2 and NaMgF3, and that silicon oxide was thought to deposited on the anodized surface by sealing treatment. Corrosion test showed that weight loss was independent of film thickness, but that estmated maximum corrosion depth increased and corrosion area ratio decreased with increasing anodizing film thickness. Coupling test between anodizing film and magnesium alloy showed the presence of galvanic current between them, in which anodizing film was cathode and magnesium alloy was anode. Corrosion behavior of anodized magnesium alloy in SST is discussed in terms of galvanic corrsoion model.
