Initial corrosion behavior of pure zinc in simulated tropical marine atmosphere

The initial corrosion behavior of pure zinc in a simulated tropical marine atmosphere was investigated using gravimetric method, scanning electron microscope combined with energy dispersive spectroscopy (SEM-EDS), X-ray diffractometry (XRD), Fourier transform infrared spectrometry (FTIR) and electrochemical impedance spectroscopy (EIS). The kinetics of corrosion process is a decelerating process following the empirical equation D=Atⁿ (n<1). The protectiveness of the corrosion product layer could be attributed to the formation of simonkolleite, Zn₅(OH)₈Cl₂·H₂O, which could inhibit the rate determining step, namely charge transfer step, of the electrochemical corrosion process. A model of the evolution process of the product layers formed on zinc was proposed. In addition, the regularity of the corrosion rate of zinc as a function of the NaCl deposition rate can be described by a power function.