Electrochemical and Analytical Studies of Corroding and Reactive Surfaces

材料的腐蚀是一个主要的工业和环境问题，具有安全、环境和主要成本问题。工业材料对腐蚀的敏感性取决于化学、冶金和环境因素的混合。局部腐蚀（点蚀、缝隙腐蚀、应力腐蚀开裂）特别隐蔽，因为虽然很少发生腐蚀，但它高度集中在化学和生物学上脆弱的位置，并可迅速导致结构失效。这使得了解腐蚀机理以及材料的性质如何影响损伤分布至关重要。对这些过程的研究需要采用涉及化学、冶金、物理和工程技术的多学科方法。本研究的总体目标是调查的功能，决定局部腐蚀的敏感性，以确定如何腐蚀损伤将被分配，并调查的过程，最终可能导致再钝化和防止腐蚀。实验技术范围从那些能够解决在原子水平上的表面反应的机械细节，那些能够确定在纳米到厘米的尺度上的材料损坏的程度和位置将被应用。这些技术将从电化学和表面分析到分析和微观。考虑到这些目标，将研究以下领域。(a)金属钝化所依赖的氧化膜的性质将以镍-铬-钼高温合金为重点进行研究。将使用电化学、X射线光电子和俄歇光谱以及飞行时间二次离子质谱技术的组合。(b)利用拉曼光谱和共聚焦激光扫描显微镜研究了镍基高温合金缝隙腐蚀损伤演化的影响因素。(c)将发展和应用显微技术（特别是电子背散射衍射和原子探针场离子显微镜）来表征控制腐蚀的物理和化学过程。(d)氧化膜及其金属衬底的关键性能，这是不可用的其他技术将确定使用电化学和中子反射计的原位组合。这些性质包括介电常数、绝对膜厚度和氢含量。研究将集中于钛和锆，后者是反应堆内重要的核材料。(d)采用电化学原位拉曼光谱技术研究了含硫化物水溶液环境中输气管道的腐蚀机理。主要目标是确定胶片特性如何随各种管道曝光条件而变化。

Corrosion of materials is a major industrial and environmental issue with safety, environmental and major cost issues. The susceptibility of industrial materials to corrosion depends on a mixture of chemical, metallurgical and environmental factors. Localized corrosion (pitting, crevice corrosion, stress corrosion cracking) is particularly insidious since, while very little corrosion occurs, it is highly focussed at chemically and metallurgically vulnerable locations and can lead rapidly to structural failures. This makes it essential to understand both the corrosion mechanism and how the properties of the material influence damage distribution. The study of such processes requires a multidisciplinary approach involving chemical, metallurgical, physical and engineering techniques. The general goals of this research are to investigate the features that dictate susceptibility to localized corrosion, to determine how corrosion damage would be distributed, and to investigate the processes that might eventually lead to repassivation and the prevention of corrosion. Experimental techniques ranging from those able to resolve the mechanistic details of surface reactions at the atomic level to those able to determine the extent and location of materials damage over the scale of nanometers to centimeters will be applied. These techniques will range from electrochemical and surface analytical to analytical and microscopic. With these goals in mind the following areas will be studied. (a) The properties of the oxide films on which metals rely for passivity will be investigated with an emphasis on nickel-chromium-molybdenum superalloys. A combination of electrochemical, X-ray photoelectron and Auger spectroscopic, and time-of flight secondary ion mass spectrometric techniques will be used. (b) The factors influencing the evolution of crevice corrosion damage on Ni superalloys will be studied using Raman spectroscopy and confocal laser scanning microscopy. (c) The development and application of microscopic techniques (especially electron backscatter diffraction and atomic probe field-ion microscopy) will be undertaken to characterize corrosion controlling physical and chemical processes. (d) Key properties of oxide films and their metal substrates which are unavailable by other techniques will be determined using an in-situ combination of electrochemistry and neutron reflectometry. These properties include the dielectric constant, absolute film thickness and hydrogen content. Studies will concentrate on titanium and zirconium, the latter being an important in-reactor nuclear material. (d) The corrosion mechanisms occurring on gas transmission pipelines in sulphide-containing aqueous environments will be studied electrochemically using in-situ Raman spectroscopy. The primary goal is to determine how film properties change with the various pipeline exposure conditions.