基于扫描电化学显微镜产生/收集和反馈模式研究纯Mg腐蚀行为

CORROSION BEHAVIOR OF PURE Mg BASED ON GENERATION/COLLECTION AND FEEDBACK MODES OF SCANNING ELECTROCHEMICAL MICROSCOPY

应用扫描电化学显微镜的产生/收集和反馈模式,研究纯Mg在NaCl和Na2SO4溶液中腐蚀过程中的微区(点、线、面)析氢行为和活性点的演变过程.实验结果显示,无论在NaCl还是Na2SO4溶液中,阴极极化和阳极极化均促进析氢,与传统集气法获得的纯Mg腐蚀过程存在负差数效应一致,但析氢速率在微区范围内波动加大,不稳定,且与极化程度有关.析氢速率随NaCl浓度增加而增加,但随Na2SO4浓度增加而减少.NaCl浓度增大、pH值降低、阳极极化有利于Mg表面活性点的产生.

Since electrochemical impedance spectroscopy, polarization curve and hydrogen collection were the main technologies for corrosion research of Mg and its alloy. However, those methods only provide the mean information of entire surface of corrosion electrode. In this work, H2 evolution and active sites of pure Mg from localized sites（point, line and surface） in Na Cl and Na2SO4 solution based on generation/collection and feedback modes of scanning electrochemical microscopy（SECM） were studied. The results indicate that both cathodic and anodic polarization are in favor of H2 evolution in Na Cl and Na2SO4 solution, which is well in line with the negative difference effect by the classical H2 collection, but the SECM results show that the H2 evolution in localized sites is not uniform and stable. The H2 evolution rate increases with Na Cl concentration increasing, which is opposite in Na2SO4 solution. The higher Na Cl concentration, anodic polarization and lower p H value accelerate the formation of active sites on pure Mg surface.