Fundamental interfacial chemical processes, structures, and compositions underlying corrosion reactions

腐蚀反应的基本界面化学过程、结构和成分

• 批准号: RGPIN-2018-06672
• 负责人: Noël, James
• 金额: $ 2.48万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=685256
• 关键词: Fundamental; interfacial; chemical; processes; structures

Many of the metals that we use to construct such diverse items as nuclear reactors, coins, aircraft, orthopaedic implants, and pop cans are so unstable that, without the protection of a 3-5 nanometres-thick layer of oxide (a “passive film”), they would quickly react with their surroundings and revert to the chemical forms in which they existed before we mined and refined them.***This project uses advanced surface analysis and electrochemical techniques capable of probing such thin layers to investigate how passive films form on titanium, zirconium, and nickel-based superalloys, their physical structure, their composition (which varies from metal to metal), and how they degrade or react with their surroundings. The goals are to learn how to form passive oxide films that resist degradation and how to make passive films that repair themselves if they become damaged.****Another significant challenge for metals is localized corrosion, in which the damage, rather than being distributed across the metal surface, is focused in a small area, resulting in deep penetration. An insidious form of localized corrosion is crevice corrosion, which occurs largely unseen in cracks and hidden areas in joints and under coatings where the narrow geometry restricts movement of chemical species into or out of the crevice. A build-up of corrosive chemical species occurs within the crevice, leading to accelerated attack.****This project develops innovative electrochemical methods to analyze and map the distribution of corrosive species and resultant corrosion damage inside crevices, which we will relate to the geometry of the crevice and the composition of the materials from which it is formed. We will also use X-ray imaging to “see” the internal structure inside a crevice as it corrodes. The knowledge gained will be used to help understand, avoid, and mitigate the effects of crevice corrosion and to design more resistant alloys.****Finally, we will explore the role of hydrogen in corrosion reactions. Hydrogen is abundant in corrosion, as it is produced by the reaction of a metal with water or acid, but difficult to detect in or on metal surfaces without destroying the metal being analyzed. We will use beams of neutrons or electrons to determine concentration of hydrogen on metal surfaces during or following corrosion reactions to investigate the possibility that surface hydrogen is responsible for two curious phenomena in corrosion called the “negative difference effect” (which accelerates corrosion of magnesium alloys) and “cathodic modification” (which protects titanium alloys from corrosion). We will also measure amounts of hydrogen-driven corrosion occurring hidden within crevices, unaccounted for in damage predictions based only on oxygen-driven corrosion occurring outside the crevice. Preliminary measurements on titanium and nickel-based alloys suggest that hydrogen reactions multiply corrosion damage by 60-500% or more.***

我们用来构建诸如核反应堆，硬币，飞机，骨科罐头和流行罐之类的潜水物品的许多金属是如此不稳定，以至于如果没有3-5纳米厚的氧化物层（“一个被动膜”）（一种“被动膜”），它们会迅速与周围的形式反应并恢复为我们的化学物质，并将其恢复到我们的层面上，并在我们的层面上进行了分析，并进行了改进的技术。能够探测如此薄的层以研究钛，锆和基于镍的超合金上的被动膜如何形成，其物理结构，其成分（从金属到金属变化），以及它们如何降解或与周围环境降解或反应。目标是学习如何形成抵抗降解的被动氧化物膜，以及如何制作被动膜，如果它们受到损坏。局部腐蚀的一种阴险形式是缝隙腐蚀，在关节和涂料下，狭窄的几何形状限制了化学物种向缝隙的运动限制了狭窄的几何形状的涂层，这在很大程度上看不见。裂缝内发生了腐蚀性化学物种的积聚，导致加速攻击。我们还将使用X射线成像在腐蚀时“查看”缝隙内的内部结构。获得的知识将用于帮助理解，避免和减轻缝隙腐蚀的影响并设计更具耐药性。合金。****最后，我们将探索氢在腐蚀反应中的作用。氢的腐蚀丰富，因为它是由金属与水或酸的反应产生的，但在金属表面或金属表面上很难检测而不会破坏被分析的金属。我们将使用中性或电子的光束来确定腐蚀反应期间或之后金属表面上的氢浓度，以调查表面氢负责腐蚀中的两个好奇现象，称为“负差异效应”（加速了镁合金的腐蚀）和“降低了磷酸化的腐蚀”（该腐蚀性）和“降低了滴管质含量”（可保护钛合金的corsosion alloys alloys yrosions corrosion salloys yrosion sarforosion sarforosion a corrosion salloys a corrosion sar corrosion sarforoys a corrosion sailoys a corrosion sailoys a corrosion sailoys。我们还将测量隐藏在缝隙内发生的氢腐蚀的量，仅基于基于氧气驱动的腐蚀而在缝隙外发生的损伤预测中未被误解。对钛和镍基合金的初步测量表明，氢反应将腐蚀损伤造成60-500％或更多。***