Injection of Vacancy-Type Defects and Hydrogen by Metallic Corrosion

金属腐蚀注入空位型缺陷和氢气

• 批准号: 0605957
• 负责人: Kurt Hebert
• 金额: $ 42万
• 依托单位: Iowa State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2010-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0605957&HistoricalAwards=false
• 关键词: Injection; Vacancy; Type; Defects; Hydrogen

TECHNICAL: Recent work in the PI's laboratory has revealed potentially important aspects of pit initiation on aluminum. In particular, positron annihilation studies have detected nanometer-scale voids near the oxide/metal interface, which because their metal surface is oxide-free, can function as highly reactive sites at which localized corrosion initiates. The observation of interfacial void formation by ambient-temperature corrosion processes has led to the hypothesis that voids result from the injection of vacancy-hydrogen defects. The project will determine the mechanism of void nucleation and growth using positron methods in combination with microscopy and surface analytical probes. Studies using high-purity Al will characterize the behavior of subsurface defects during a simple corrosion process, including effects due to trapping of defects by metal solute atoms. In tandem with the experiments, an atomistic-level simulation of void formation will be developed, based on calculated energies governing defect formation, binding, and mobility, derived from rigorous theoretical approaches. The combined experimental-theoretical approach will provide a fundamental basis of understanding for formation of corrosion-relevant defects, as affected by metal-phase composition. The results are expected to elucidate the mechanism of hydrogen entry into aluminum during corrosion, and its diffusion and reactions in the near-surface region. NON-TECHNICAL: Pitting corrosion, in which metal dissolution is confined to a small area on an otherwise oxide film-protected surface, is widespread among structural metals. Since the nature of inherent surface defects where pits form is not well understood, damage due to pitting cannot be effectively predicted. Results are also of critical interest for understanding of environment assisted cracking, and so the fundamental understanding obtained should impact this field. Through this work, students will be trained by an interdisciplinary team assembled from faculty in chemical engineering, physics, materials science and chemistry. They will learn to bring condensed matter physics modeling approaches into the realm of engineering science, in order to confront a problem of significant economic relevance. Even in today's atmosphere of interdisciplinary research, such educational experiences are unusual. Student training will take advantage of the strong presence at Iowa State of graduate and undergraduate programs promoting under-represented groups, both at the Departmental and University levels.

技术：PI实验室的最新工作揭示了铝上矿坑启动的潜在重要方面。特别是，正电子的歼灭研究检测到氧化物/金属界面附近的纳米尺度空隙，因为它们的金属表面不含氧化物，它可以充当高度反应性的位点，在该位点上，局部腐蚀引发了局部腐蚀。通过环境温度腐蚀过程观察界面空隙的形成导致了这样一种假设，即在空位 - 氢缺陷的注射下导致空隙。该项目将使用正电子方法与显微镜和表面分析探针结合使用空隙成核和生长的机制。使用高纯度AL的研究将表征简单腐蚀过程中地下缺陷的行为，包括由于金属溶质原子捕获缺陷引起的影响。与实验同时，将基于根据严格的理论方法得出的缺陷形成，结合和迁移率的计算能量来开发空隙形成的原子级模拟。合并的实验理论方法将为受到金属相组成的影响，为形成与腐蚀相关的缺陷形成的基本基础。预计该结果将阐明在腐蚀过程中氢进入铝的机理，以及其在近地表区域的扩散和反应。非技术：矿化腐蚀，其中金属溶解仅限于原本氧化物膜保护的表面上的小区域，在结构金属中普遍存在。由于固有的表面缺陷的性质无法很好地理解凹坑的形成，因此无法有效预测由于斑点而造成的损害。结果对于理解环境辅助破裂也具有关键的兴趣，因此获得的基本理解应影响该领域。通过这项工作，学生将接受由化学工程，物理，材料科学和化学教师组成的跨学科团队的培训。他们将学会将凝结的物理建模方法带入工程科学领域，以面对重大经济相关性的问题。即使在当今的跨学科研究氛围中，这种教育经历也不寻常。学生培训将利用在爱荷华州的研究生和本科课程的强大领域，这些课程促进了在系和大学级别的代表性不足的群体。