Corrosion Behavior of Pure Zinc in Acidic Red Soil under AC Interference

The corrosion behavior of pure zinc in red soil under the interference of AC with current density of 10-100 mA/cm² was studied through static corrosion weight loss test. The corrosion rate was calculated using the weight loss method, and the electrode potential was continuously recorded using a 500 Hz data acquisition card. The surface morphology was observed using a stereo microscope and scanning electron microscopy (SEM), while the composition and morphology of the corrosion products were analyzed using energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The results show that the corrosion rate of pure zinc under an applied AC current of 10 mA/cm² to 100 mA/cm² was 3.243 to 9.675 times that without AC interference. By substituting the weight loss into Faraday's law to calculate the net Faraday charge of corrosion, it was found that the efficiency of net Faraday charge produced by AC interference of 10 mA/cm² to 100 mA/cm² was only 1.852% to 4.783%. There was a linear relationship between the total anodic charge produced by the alternating current and the net Faraday charge, and a relationship formula to estimate the corrosion rate through current density had been established, that was v_C=2.880+0.071i_max(10 mA≤i_max≤100 mA). The corrosion potential of pure zinc exhibited a sinusoidal variation pattern, with the amplitude of change increasing as the AC current density increased. Compared to the corrosion potential of pure zinc, there was a net negative shift in corrosion potential, and this negative shift increased with the increase of AC current density. After applying the AC current, the corrosion traces on the surface of pure zinc became more severe and pitting was induced. After 24 hours of AC current interference, the corrosion products on the surface of pure zinc were ZnO, Zn(OH)₂, Zn₄Si₂O₇(OH)₂, and SiO₂.