Initial corrosion behavior of pure zinc in simulated tropical marine atmosphere
(1. Environmental Corrosion Center, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China;
2. School of Materials Science and Engineering, University of Science and Technology of China, Shenyang 110016, China)
2. School of Materials Science and Engineering, University of Science and Technology of China, Shenyang 110016, China)
Abstract: 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.
Key words: zinc; corrosion kinetics; corrosion product; electrochemical impedance spectroscopy (EIS); simonkolleite