摘要
利用激光电子散斑干涉(ESPI)、电化学噪声(EN)及三维视频显微技术研究304不锈钢在3,5%NaCl溶液中点蚀早期单个蚀孔的发展动力学及其机理.结果表明在0.05 V恒电位极化下,点蚀过程可分为4个阶段:首先,电流噪声在740 s时发生剧烈波动,钝化膜开始破裂,点蚀孕育期为740s;其次,ESPI图像在750 s时产生可见光斑,稳态蚀孔萌生期为10 s;再次,750—780 s时,蚀孔的发展速率不断增加,表明点蚀处于活性溶解期:最后,蚀孔生长速率迅速下降,发生钝化,而在793 s后,由于出现次生蚀孔,生长速率再次上升.使用三维视频显微镜观察蚀孔形貌并测量蚀坑体积的变化,印证了由腐蚀产物浓度分析法得到的单个蚀孔的生长速率,并在蚀坑底部观察到了次生蚀孔.
Pitting rate of a single pit and pitting mechanisms of the 304 stainless steel in 3.5%NaC1 solution were investigated by utilizing electronic speckle pattern interferometer （ESPI）, electrochemical noise （EN） and three dimensional video microscope. The results show that under 0.05 V polarization, the pitting corrosion process can be divided into four stages： drastic fluctuations of the current noise occured at 740 s, which means the passivation film was breaking, thus it can be concluded that the span of pitting incubation period is 740 s; a speckle occurred on the ESPI image at 750 s, thus the span of initiation period of the steady pitting is about 10 s; the growth rate of the pit increased during 750--780 s, which indicates that the pit corrosion is in active dissolution period; since then, the growth rate of the pit declined rapidly which means the pit was repassivated. After 793 s, the growth rate of the pit raised again as secondary pits emerged. The pit image was observed and its volume was measured by three dimensional video microscope, and the results were in agreement with those which were obtained by corrosion product concentration analysis. Some secondary pits were found in the bottom of the Pit in three-dimensional reconstruction images.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2012年第7期807-814,共8页
Acta Metallurgica Sinica
基金
国家自然科学基金资助项目51071083~~
