Corrosion resistance and mechanism of zinc rich paint in corrosive media

Zinc is widely used as sacrificial protecting coating in process industries, constructions and buildings. Due to the fact that, zinc is less noble metal and cathodically protects the steel from corrosion. A zinc rich paint (ZRP) was sprayed onto metal substrate, using electrochemical impedance spectroscopy (EIS) the electrochemical properties was investigated. Coated samples were immersed in 0.5 M NaCl solution in various time period, EIS measurements were regularly performed. Then, an electrical equivalent circuit (EEC) was applied to model electrochemical mechanism. Using this model, it was found that the dispersion of the zinc particles was inhomogeneous. The electrochemical responses was slightly different with the increases of coating thickness and zinc contents.