Influence of substrate orientation on anodic films of aluminium

Abstract Three types of aluminium single crystals of crystallographic orientation (100), (110) and (111) respectively were anodized under typical anodizing conditions. It was found that the influence of the substrate orientation on the anodized films varied with the anodizing conditions. The films on the (111) plane gave the lowest reflectance. When pulsed d.c. was used, the reflectance difference between the films on each plane became particularly large, e.g. a difference of above 15% existed between films on the (100) and the (111) planes anodized for 40 min in H 2 SO 4 . The microstructure and dissolution behaviour of the films contributed to the differences of colour and other properties exhibited by films on each plane.