A method for determining the layer thickness of the aluminium layer and the iron - aluminum - alloy layer of aluminized steel sheets or - bands

摘要

Thickness of the aluminium coating (and of the aluminium-iron layer) can be rapidly measured when the plant is in operation by anodical dissolution in an electrolyte contg. (in g/l.): AlCl3 40-60, citric acid 40-60, FeCl2 120-150, and KCl 5-15, at a pH of 0.8-1.2 at room temp. and a current density of 40-55 mA/cm2, and continuous recording of the potential-time curve, which shows separate steps for the Al and Al-Fe layers. The anode is made from pure Al, and a calomel electrode is used as a reference electrode.