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

Abstract

Ternary Ni-Zn-P alloy thin films with a thickness of 15-20 μm 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 ZnSO₄·7H₂O 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 <em>vs.</em> saturated calomel electrode (SCE) for the corrosion potential and 13.4 μA·cm^-2 for the corrosion current density. The calculated value for the corrosive attack protection efficiency is 67.7%.