A Study On Corrosion Resistance Of Aluminum Cathode And Adhesion In Zinc Electrodeposition

Aluminum cathodes are corroded by acid mist,electrolyte and the fluoride,chloride ion in zinc eletrowinning plant operation.This causes side damage and fracture of cathode and increases production costs.In the meantime,the sticking problem resulting from surface deterioration and the effect of fluoride and chloride ion increases difficulties in removing zinc plates from cathodes,which discontinued stripping operation.In this paper,surface modification of the aluminum cathode was performed by boiling water sealing,cerium salt sealing and sol-stearic acid sealing to form the boehmite layer with corrosion resistance.Copper accelerated acetic acid salt spray test and corrosion electrolyte weight loss test were performed to study the differences of corrosion resistance and work out the optimum scheme.Cathodic polarization curve test,Tafel polarization curve test and galvanostatic polarization curve test were used to investigate the effects of surface treatment processes on polarisation,corrosion resistance and energy consumption.Electrodeposition to study zinc nucleation,current efficiency,adhesion and the surface,thickness,weight of cathode was carried out.The result showed that the corrosion resistance of aluminum cathode sealed by boiling water,cesium salt and sol-stearic acid increased respectively,and the sol-stearic acid sealing worked better.The results of electrochemical measurement demonstrated the sol-stearic acid sealing can contribute to the higher hydrogen evolution potential resulting in more difficult hydrogen evolution,a far lower corrosion current of the sealed aluminum cathode than that of the untreated and lower zinc deposition potential leading to energy saving.In addition,the adherence strength of the cathode sealed by sol-stearic acid was reduced by 25–30% than that of the untreated,which decreased the stripping difficulty effectively.In industrial zinc electrodeposition,the probility of fracture above the electrolyte/air interface,insulation-bar`s dropping and sticking was far lower than that of the untreated.Moreover,the cathode sealed by solstearic acid had the more stable current efficiency and a lifespan 30% longer than that of the untreated.In summary,the sol-stearic acid sealing can be used to improve corrosion resistance of cathode,prolong its lifespan and decrease sticking problem in zinc electrodeposition,which is of good industrial value.