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1.引言金属的局部腐蚀是在金属或合金表面或内部局部发生的腐蚀现象,例如点腐蚀(小孔腐蚀)、缝隙腐蚀、应力腐蚀(SCC)、晶间腐蚀等等。在局部腐蚀过程中,通常同时存在一相对“钝化”而积较大的阴极区(还原反应在此进行)和一面积较小的活化的阳极区(氧化,或说腐蚀反应在此进行)。在影响金属和合金的钝性和活性的诸因素中,金属的电极电位和介质的pH值通常起着极其重要的作用。因此,由M.布拜(M.Pourbaix)教授所创造的电位(E)-pH图(Pourbaix图)越来越广泛地被用于局部腐蚀的研究工作中。关于应用E-pH图研究局部腐蚀的基本方法,可参阅参考文献(1～6]。本文着重举例介绍近年来在这方面的某些最新的进展。
1. INTRODUCTION Local corrosion of metals is localized corrosion on or in the surface of metals or alloys such as pitting corrosion (crevice corrosion), crevice corrosion, stress corrosion (SCC), intergranular corrosion, and the like. During local etching, a relatively “passivated” relatively large cathode area (where the reduction reaction takes place) and a smaller activated anode area (oxidation or corrosion reaction) are usually present simultaneously. . Of the factors that affect the passivity and activity of metals and alloys, the electrode potential of the metal and the pH of the medium generally play an extremely important role. Therefore, the Potential (E) -pH plot (Pourbaix plot) created by Professor M. Pourbaix is increasingly used in the study of localized corrosion. For basic methods of studying localized corrosion using E-pH charts, see References (1 ~ 6). This article highlights some of the most recent advances in this area in recent years.