Influence of various inhibition conditions on the structure of zinc electrodeposited on a rotating disc electrode from a sulphate bath

Abstract

The influence of hydrodynamic conditions and of cathodic inhibition on zinc electrodeposition kinetics from weakly acid sulphate baths and on its structure has been studied. The investigations were carried out in both pure electrolyte and solutions with synthetic inhibitors added. It has been found that in the zinc electrocrystallization process two types of inhibition occur— primary and secondary (autoinhibition). The conditions of cathode deposit formation — and consequently the crystallites orientation — are signifactly altered by hydrogen codischarge. Within the cathodic layer, zinc hydroxide is produced which acts as a secondary inhibitor, resulting in the texture type of deposited coatings being modified. In the conditions examined, adding primary inhibitors — synthetic organic compounds— did not significantly influence either the cathodic process or the deposit texture, while the surface morphology was obviously affected.