Effect of Continuous Rotation Evolutional Control on the Surface Color of Anodized Al–Mg Alloys

Abstract

Al–Mg alloys treated by continuous rotation evolutional control (CREO) were anodized and colored by alternating current electrolysis at 10 V in sulfate solutions containing Cu, Sn, Ni, or Co at 303 K. Electrolysis turned the anodized Al–Mg alloys to rufous (Cu), yellow to gold (Sn), or reddish brown (Ni and Co). Their lightness was enhanced significantly by CREO, regardless of the metal deposited. The gloss of the Al–Mg alloys decreased probably due to increase in surface waviness resulting from CREO, and the enhancement in lightness with CREO is attributed to this decrease in the glossiness. SEM images showed that the micropore density in anodic oxide films on Al–Mg alloys decreased as a result of CREO. The decrease in the micropore density is assumed to enhance the lightness of colored Al–Mg alloys treated by CREO.