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.***

我们用来构造核反应堆、硬币、飞机、整形外科植入物和易拉罐等各种物品的许多金属都非常不稳定，如果没有 3-5 纳米厚的氧化物层（“钝化膜”）的保护， ”），它们会快速与周围环境发生反应，并恢复到我们开采和精炼它们之前存在的化学形式。***该项目使用先进的表面分析和电化学技术，能够探测如此薄的层，以研究如何钛、锆和镍基高温合金的钝化形式、它们的物理结构、它们的成分（因金属而异）以及它们如何降解或与周围环境发生反应，目标是学习如何形成钝化氧化膜。抵抗降解以及如何制造在损坏时能够自我修复的钝化膜。****金属的另一个重大挑战是局部腐蚀，其中损坏不是分布在整个金属表面，而是集中在一个小区域，导致深局部腐蚀的一种隐蔽形式是缝隙腐蚀，这种腐蚀在接头和涂层下方的裂缝和隐藏区域中发生，这些区域的狭窄几何形状限制了化学物质进出缝隙的运动。发生在缝隙内，导致加速攻击。****该项目开发创新的电化学方法来分析和绘制腐蚀物质的分布以及缝隙内由此产生的腐蚀损伤，我们将其与缝隙的几何形状相关联我们还将使用 X 射线成像来“查看”缝隙内部腐蚀的结构，所获得的知识将用于帮助理解、避免和减轻缝隙腐蚀的情况。缝隙腐蚀的影响并设计更耐腐蚀的合金。****最后，我们将探讨氢在腐蚀反应中的作用。氢在腐蚀中含量丰富，因为它是由金属与水或酸反应产生的，但难以在金属内部或金属上检测到我们将使用中子或电子束来确定腐蚀反应期间或之后金属表面上的氢浓度，以研究表面氢导致两种奇怪的腐蚀现象（称为“负差效应”）的可能性。 “”（加速镁合金的腐蚀）和“阴极改性”（保护钛合金免受腐蚀）我们还将测量隐藏在缝隙中的氢驱动腐蚀的数量，而这些腐蚀在仅基于氧驱动的损坏预测中未被考虑在内。对钛和镍基合金的初步测量表明，氢反应会使腐蚀损伤增加 60-500% 或更多。***