A metallurgical approach to civil- and mechanical-engineering corrosion problems

解决土木和机械工程腐蚀问题的冶金方法

• 批准号: RGPIN-2020-04530
• 负责人: Hansson, Carolyn
• 金额: $ 3.35万
• 依托单位: University of Waterloo
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=760420
• 关键词: metallurgical; approach; civil; mechanical; engineering

The proposed program addresses two major problems: (i) the corrosion of reinforcing steels in concrete and (ii) the corrosion and stress corrosion cracking behaviour of aluminum alloys for structural automobile components. In both cases, the corrosion is predominantly caused by exposure to de-icing salts. While these are practical engineering problems in need of effective solutions, a basic understanding of the mechanism of corrosion is required to optimise the solutions. The mechanisms are influenced by the composition, microstructure and surface condition of the alloys, and the in-service environmental conditions. The anti-icing agents applied to Ontario highways are no longer simply "rock salt" but are concentrated brines of different chloride salts: calcium chloride, magnesium chloride as well as sodium chloride and a mixture of all three chlorides. The goal of the proposed program is to develop an understanding of the influence of the different salts on corrosion behaviour of metals and alloys both in the highway infrastructure and automobile components. This will enable the most appropriate anti-icing agents to be selected for specific applications. During the current Discovery Grant period, the development of the passive films in concrete and their breakdown by sodium chloride on both carbon and stainless-steel reinforcement have been studied using the Mott Schottky analysis. It is anticipated the application of calcium chloride and magnesium chloride as anti-icing agents will be even more deleterious than sodium chloride to the reinforcement. We have already shown the calcium-and magnesium-based salts affect the mechanical properties of concrete: they reduce the compressive strengths of concrete by as much as 30% over a period of five years. In the proposed program, these effects will be further investigated. Since highway structures are required to provide service over many decades, this will include thermodynamic calculations to provide expected functionality in the long-term. Most corrosion studies of aluminum alloys have been in sodium chloride environments but it is expected that the corrosion can will be influenced by the different de-icing agents. The general corrosion behaviour will be investigated by conventional electrochemical techniques, while the localized corrosion of individual phases will be studied by scanning electrochemical microscopy. X-ray photoelectron spectroscopy and Mott-Schottky analysis will be used to study the structure, semiconducting properties and composition of the passive films formed before and after exposure to the salts. During the course of the program, two doctoral students and three master's students will be conducting their research on these topics. There is a demand for engineering graduates with a knowledge of corrosion, as evidenced by the multiple offers of employment received by my recent graduates.

提出的计划解决了两个主要问题：（i）在混凝土中加固钢的腐蚀和（ii）铝合金对结构汽车组件的腐蚀和应力腐蚀开裂行为。在这两种情况下，这种腐蚀主要是由于暴露于去冰盐而引起的。尽管这些是需要有效解决方案的实用工程问题，但需要对腐蚀机制的基本理解来优化解决方案。这些机制受合金的组成，微观结构和表面状况以及服务中环境条件的影响。适用于安大略高速公路的抗染色剂不再简单地“岩盐”，而是不同氯化物盐的浓盐水：氯化钙，氯化镁以及氯化钠以及所有三个氯化物的混合物。该计划的目的是建立对高速公路基础设施和汽车组件中不同盐对金属和合金腐蚀行为的影响的理解。这将使最合适的抗染色剂被选为特定应用。在当前的发现赠款期间，使用Mott Schottky分析研究了混凝土中的被动膜的开发以及氯化钠对碳和不锈钢增强的破裂。预计将氯化钙和氯化镁施用为抗冰剂将比氯化钠更有害。我们已经显示了钙和镁的盐会影响​​混凝土的机械性能：它们在五年内将混凝土的抗压强度降低了30％。在拟议的计划中，将进一步研究这些效果。由于需要高速公路结构在数十年中提供服务，因此这将包括热力学计算，以便长期提供预期功能。 铝合金的大多数腐蚀研究都在氯化钠环境中，但预计这种腐蚀会受到不同冰水剂的影响。一般的腐蚀行为将通过常规电化学技术研究，而单个相位的局部腐蚀将通过扫描电化学显微镜研究。 X射线光电子光谱和Mott-Schottky分析将用于研究在暴露于盐之前和之后形成的被动膜的结构，半导体特性和组成。 在计划的过程中，两名博士生和三名硕士学生将对这些主题进行研究。我最近毕业生收到的多重就业机会证明了对具有腐蚀知识的工程毕业生的需求。