基于散粒噪声理论分析锌合金(ZnAl4Cu1)在干湿循环下的腐蚀行为

摘要

采用电化学噪声理论,研究锌合金(ZnAl4Cu1)在3.5％(质量分数)NaCl,7.3％(质量分数)Na2SO4和模拟酸雨溶液中干湿循环条件下的腐蚀行为.采用快速傅里叶变换(FFT)、快速小波变换(FWT)和散粒噪声理论结合统计方法分析原位电化学电位噪声.散粒噪声分析的fn累计曲线图表明,在干循环中电子转移事件的频率高于湿循环中的,在NaCl溶液中的腐蚀比在Na2SO4中的腐蚀更均匀,腐蚀事件的条件产生速率r(t)对于受扩散控制的事件来说随着干湿循环时间的延长而降低.锌合金在NaCl溶液中湿循环时,均匀腐蚀和扩散控制的事件的r(t)值最大；在Na2SO4溶液中湿循环时,点蚀事件的r(t)值最大.在酸雨溶液中可明显观察到锌合金的晶间腐蚀.%The corrosion behaviors of zinc alloy (ZnAl4Cu1) in 3.5％ (mass fraction) NaCl,7.3％ (mass fraction) Na2SO4 and simulated acid rain solutions were investigated using electrochemical measurements.The potential noise during dry-wet cycle was monitored and analyzed by fast Fourier transform (FFT),fast wavelet transform (FWT),shot noise theory and stochastic theory.Cumulative probability curves of event frequency fn indicate that the corrosion events in the dry cycles are greater than those in the wet cycles.Uniform corrosion was observed in the NaC1 solution compared with more localized corrosion in the Na2SO4 solution,which is evidenced by FWT and SEM.Conditional events generation rate r(t) for diffusion controlled reactions decreases with increasing the time.r(t) values for uniform corrosion and diffusion controlled process are the largest in the wet cycle in 3.5％ NaCl solution.The values of r(t) for pitting corrosion in Na2SO4 solution are observed to become large during spraying periods,and r(t) for pitting corrosion has the largest value in the Na2SO4 solution.The intergranular corrosion of zinc is serious in simulated acid rain solution.