中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 19 No. 2 April 2009 |
（1. Department of Chemistry, College of Science, Zhejiang Forestry University, Hangzhou 311300, China;
2. Department of Chemistry, Zhejiang University, Hangzhou 310027, China;
3. College of Chemical Engineering and Materials Science, Zhejiang University of Technology,
Hangzhou 310032, China;
4. Key Laboratory for Ultra-light Materials and Surface-treatment Technology of Education Ministry of China,
Harbin 150001, China）
Abstract: The corrosion process of AZ91D magnesium alloy in neutral 1% (mass fraction) sodium chloride aqueous solution was investigated by electrochemical noise(EN), SEM and EDX. Fractal theory was primarily used to depict the corrosion process of the alloy. The fast wavelet transform(FWT), as well as the fast Fourier transform(FFT), was employed to analyze the EN data. The results show that the overall corrosion process can be described by three stages. The first stage corresponds to the pit nucleation and growth; the second stage involves the growth of a passive oxide layer; and the third stage involves reactivation. With increasing immersion time, fractal dimension increases fast initially, fluctuates in the medium and increases again at last. Pitting corrosion and fractal dimension increase due to the initiation and formation of pits in the initial and the end of immersion, while depresses due to the passivation in the medium period. The results of SEM and EDX support the above conclusions.
Key words: AZ91D magnesium; corrosion; electrochemical noise; fractal dimension
