This process is used in the iron and steel industry for the production of electrolytically zinc-plated iron coil, from a lightly acid Zinc sulphate solution.
The coil, with variable width ranging from around 600 to 1400 mm, quickly goes through a series of electrolytic cells under cathodic polarisation. Anodes can be in soluble Zinc, Lead or activated Titanium. The latter has considerable advantages compared with the others due to stability in its size, lightness and non polluting towards the bath. It doesn’t require maintenance and compared to Lead it enables the benefit of energy saving, thanks to its low over-voltage for the oxygen discharge.
Due though to frequent contacts between coil and Anode, caused by the extreme proximity ( < 1 cm) which the process requires, short circuits arise which cause damages that compromise the performance and the duration of the coating.
Chemical Newtech has developed a coating which is particularly resistant to this kind of strain with protective action on the titanium base which, following the local polarity inversions caused by the short circuits, loses the passivation and protective TiO2 layer and tends undergo corrosion, with subsequent detachment of the coating layer.
This coating’s special formulation, with Iridium, Tantalum and Tin Oxide is particularly compact and it allows a very good separation of the Titanium base from the solution and therefore a barrier from the attack of the acids of the solution itself.