Direct Current Electrodeposition of Tin for the Colouration of Aluminium Oxide Films, in the Presence of Malachite Green

SummaryThe present study deals with the colouration of porous anodic aluminium oxide films by the dc electrodeposition of tin metal, in the presence of the cationic dye Malachite Green in these films. The adsorption of this dye at the pore base surface is assisted electrochemically during the process of colouring. The adsorbed dye molecules have a positive influence on the changes in the barrier layer characteristics (thickness, number of defects, etc.) and on the intensity of colour, while their influence on the uniformity of colour becomes negative after the second min of treatment at 13 V dc. The intensity of the colour obtained increases rapidly with the increase of colouring voltage until 13 V and 3 min, at a concentration of 1.42 g 1−1 of the dye in the colouring solution (SnSO4+H2SO4) and then tends to become stable. In this case, a deep bronze colouration is achieved, while in the absence of the dye it is light bronze.