Controlling the roughness of aluminium substrates by electrochemical processing

Electrochemical processesing can be used to obtain aluminium surfaces with a well defined roughness. This is based on the use of DC or AC of polarisation of aluminium in an acid eletrolyte containing either chloride or nitrate anions. The roughness is obtained by a controlled pitting process. This DC or AC electrograining process is used for the preparation of aluminium litho material or for the production of Al capacitor foil. In the case of aluminium litho the water retentive properties and the adhesion of the polymer film are important. In the case of capacitor foil it is important to create a very high specific surface area. In the paper the electrochemical process is introduced and the link between the basic electrochemical parameters, such as aluminium alloy composition, current density, electrolyte composition, type of the anion in relation to the obtained morphology is discussed.