Effect of Alloying Elements on the Colour Development of Anodised Al-Mg-Si Alloys
Colour of the anodised Al-Mg-Si alloys was quantified by spectrophotometric method defining L* (lightness), a* (greenness-redness) and b* (blueness- yellowness) values. All alloys exhibited yellow and green colour. The yellowness of the anodised surfaces increased significantly with the increase of Cu while increasing Mn reduced the greenness. Effect of trace elements V and Ni was negligible while Zn caused slightly yellowness. Fe reduced the lightness of the surfaces, while its effect on colour was insignificant. Smut layer being formed during alkaline etching (prior to anodising) was desmutted/deoxidised in different acid solutions, some of which failed to clean the etched surfaces. Remaining smut however caused minor effect on colour.
Knut Marthinsen, Bjørn Holmedal and Yanjun Li
E. Senel and M. Hallenstvet, "Effect of Alloying Elements on the Colour Development of Anodised Al-Mg-Si Alloys", Materials Science Forum, Vols. 794-796, pp. 247-252, 2014