材料期刊网

The corrosion behavior of zinc and its alloy under thin electrolyte layers (TEL) in 0.1M NaCl solution was investigated by cathodic polarization curves and EIS. There was only one phase in pure zinc while zinc alloy consisted of eutectic phase and primary phase. Corrosion rate of zinc alloy was faster than that of pure zinc due to the effect of the micro-galvanic couples between the primary phase and the eutectic phase. The results indicated that corrosion rate of zinc alloy was greatly enhanced under TEL than that in bulk solution. Pure zinc exhibited minimum corrosion resistance as TEL decreased to 198 μm. Zinc and its alloy exhibited localized corrosion under TEL while it was more uniform in bulk solution. There were two capacitive loops in high frequency (HF) and middle frequency (MF) respectively, with finite length diffusion in low frequency (LF) presented in EIS. For pure zinc under TEL below 300 μm an additional inductive loop presented in MF-LF. The corrosion products and morphology were respectively examined by X-ray diffraction (XRD), FTIR (Fourier Transform Infra Red) and SEM-EDS. FTIR micro spectroscopy results indicated that the component of the corrosion products was similar at different section of the specimen surface but different in content.