Electrochemical studies of general and localized corrosion processes

本研究的主要目的是建立模型来预测工业和环境重要材料的腐蚀过程随时间的演变。关键领域包括高水平核废料储存库和天然气输送管道钢中重要材料的腐蚀。环境绩效评估模型的主要目标是证明所选择的情景将满足设定的监管目标。工业腐蚀模型的主要目标是要么证明系统适合继续使用，要么优化维护操作的调度，以最小化过程干扰。在大多数这些应用中，材料表面的氧化膜和/或腐蚀产物沉积是防止腐蚀的主要防御。如果要合理使用它们，就必须彻底了解它们的性质以及它们对时间和暴露环境的反应。本建议的主要焦点是必要的机制理解和确定基本模型参数值的实验发展。建议研究局部腐蚀过程的各个方面，从局部过程启动必须失效的薄膜和沉积物的性质，到特定腐蚀过程的损伤函数的发展，这些函数描述了在重要暴露期间损伤是如何累积的。这将通过耦合电化学技术来实现，电化学技术在这些问题上有着悠久的应用历史，以及我们在过去几年中开发或适应这些应用的一系列新的表面分析技术。其中包括电化学方法与中子反射法的新型耦合，以及扫描电化学显微镜的适应，这种技术可以绘制不均匀分布的腐蚀部位。

The primary aim of this research is to develop models to predict the evolution with time of industrially and environmentally important materials corrosion processes. Key areas of interest include corrosion of important materials in high level nuclear waste repositories and gas transmission pipeline steels. The primary goal of an environmental performance assessment model is the demonstration that the chosen scenario will meet the set regulatory goals. The primary goal of an industrial corrosion model is to either demonstrate that the system is fit to remain in service or to optimize the scheduling of maintenance operations for minimal process disturbance. In the majority of these applications oxide films and/or corrosion product deposits on the surface of the materials are the primary defense against corrosion. A thorough understanding of their properties and how they respond with time and exposure environment is essential if their use is to be justified. The primary focus of this proposal is the experimental development of the necessary mechanistic understanding and the determination of the values of essential model parameters. It is proposed that all aspects of localized corrosion processes be studied, from the properties of the films and deposits which must fail for localized processes to initiate, to the development of damage functions for specific corrosion processes, which describe how damage accumulates over the important exposure period. This will be achieved by coupling electrochemical techniques, which have a long history of application to these problems, with a range of novel surface analytical techniques which we have developed or adapted to these applications over the past few years. These include the novel coupling of electrochemical methods and neutron reflectometry and the adaptation of scanning electrochemical microscopy, a technique which can map inhomogeneously distributed corrosion sites.