Electrochemical behaviour of ternary Ni-Zn-P thin films deposition on steel substrate

Ternary Ni-Zn-P alloy thin films with a thickness of 15-20 mu m are considered as a replacement for cadmium sacrificial coatings for anticorrosive protection of steel parts working in highly corrosive media. Anticorrosive Ni-Zn-P thin films has been electrochemically deposited from aqueous sulphate solutions on carbon steel substrate. The influence of bath composition (variable ZnSO4 center dot 7H(2)O contents) and electrodeposition type (potentiostatic or galvanostatic) on physical-chemical and corrosion characteristics of obtained films have been studied. Films are characterized by energy dispersive analysis (EDAX) and scanning electron microscopy (SEM). The corrosion tests are performed in 3% NaCl solution with optimal resulting values of -916.2 mV vs. saturated calomel electrode (SCE) for the corrosion potential and 13.4 mu A.cm(-2) for the corrosion current density. The calculated value for the corrosive attack protection efficiency is 67.7%.