Comparison Study of Potassium Hydroxide (Caustic Potash) Alkaline Non Cyanide Zinc VS Sodium Hydroxide (Caustic Soda) Alkaline Non Cyanide Zinc

摘要

Haring cell and Hull cell studies were carried out to evaluate zinc deposit plating efficiencies and throwing power, appearance etc. of alkaline non cyanide zinc baths using Sodium Hydroxide and Potassium Hydroxide electrolytes. Study showed that even at low zinc metal concentration ( 1.0 oz/gal) under certain conditions up to 95percent plating efficiencies can be achieved from both the alkaline non cyanide zinc baths. Plating efficiency decreases as current density increases with both the plating baths however, Potassium Hydroxide bath gave higher plating efficiencies than Sodium Hydroxide bath at higher current densities applied in this test series. Carbonates were not freezing out from Potassium Hydroxide bath. Presence of carbonate reduced plating efficiency in both the plating baths although Potassium Hydroxide bath gave higher plating efficiency than Sodium Hydroxide bath. Zinc plate distribution or throwing power was inferior with Potassium Hydroxide bath at lowest current density utilized in this test although it was equal to Sodium Hydroxide bath at other two higher current densities applied in this test series. Distribution or throwing power and efficiency remained just about unchanged with hard water. Effect of hard water on appearance was inconclusive at this time. In general higher current density appearance was better with Potassium Hydroxide bath than Sodium Hydroxide bath. Potassium Hydroxide bath costs higher than Sodium Hydroxide bath.