DETAILS OF ELECTROCHEMICAL TIN DEPOSITION ON STEEL FROM FERROSTAN BATH

Results of an electrochemical evaluation of the most commonly used bat h for industrial electroplating of steel are presented. Cyclic voltamm etry, linear sweep voltammetry and chronopotentiometry results were ob tained with an electrolytic cell under industrial conditions of temper ature, concentration of electroactive species, steel quality and anode . Characteristic electrochemical values (Ep, Ip) and interrelationship of these parameters with sweep potential rate, nu, as well as informa tion about mass transference and crystallization of metallic tin on th e steel sheet are discussed. An irreversible process with progressive nucleation and further tridimensional growth can explain these results , which are also confirmed by Scanning Electronic Microscopy(SEM). Usi ng current densities of 2.9 A dm(-2) an optimal deposition time of 90 s could be defined. Under these conditions an uniform, homogeneous, fi ne grain and low porosity deposit was obtained.