STUDY OF THE VISUAL AND THE UNIFORM APPEARANCE OF THE ETCHING AND ANODIZING OF Al ALLOYS

摘要

The surface mattness and colour of etched and anodized Al 1050 and Al 5005 surfaces have been investigated. To this end two physical properties have been measured, i.e. the angle resolved surface scattering and the total integrated scattering. It is revealed that the AA1050 substrate is intrinsically highly reflecting and that the anodic oxide film formed on AA1050 is relatively transparent. AA5005 and its anodic oxide are however optically absorbing. Furthermore, AA5005 has a compositional interphase region at the surface compared to the bulk properties of the alloy. This causes a transient optical behaviour if the alloy is anodized. Preliminary etching removes this interphase and creates a much more regular reflective behaviour. It also increases the mattness of the surface. Anodizing does not affect the mattness but rather the specular and near specular reflection.