SBIR Phase I: Self-healing Corrosion Protection Coatings to Enable Use of Magnesium in Automobiles

该小型企业创新研究（SBIR）第一阶段旨在通过为镁合金部件开发一种自修复、无铬转化涂层，使镁合金在汽车中得到广泛应用。与镁的使用相关的重量减轻将使汽车更省油，并减少二氧化碳排放。在汽车应用中使用镁的主要障碍是其对腐蚀的高度敏感性。虽然铬酸盐转化涂层提供了足够的腐蚀抑制，六价铬是一种致癌物质。因此，汽车制造商不得不使用铬酸盐涂层的替代品。商业非铬预处理显示出阻隔性能，但不提供足够的损伤响应行为，导致相对于铬酸盐涂层的性能差。因此，需要一种显示出与铬酸盐类似的损伤响应腐蚀行为的无铬预处理。在这项研究中提出的关键创新是一种新的非铬腐蚀抑制预处理技术，预计将赋予自我修复行为的发展。如果成功，将为第二阶段计划奠定基础。在第二阶段计划中，将在模拟使用条件下进行测试，从而实现原型汽车部件的制造和测试。该研究的更广泛影响将主要集中在汽车应用领域，其中使用重量更轻的镁合金（与目前使用的铝合金相比）将有助于减少汽车尾气中的二氧化碳排放。目前，一些部件（变速器壳体和转向柱）由镁合金制成，但这项研究将允许将镁合金用于其他部件，如发动机缸体，齿轮箱，离合器壳体和发动机支架。该技术也将适用于航空航天和水下应用中使用的铝合金。无铬酸盐技术不仅将为该公司带来可观的收入（估计数百万美元），而且还将帮助美国汽车制造商为海外市场，特别是欧盟（EU）提供更轻、更省油的汽车。这项工作将发表在领先的腐蚀科学期刊和会议上，从而为大学提供新的知识，以培训和教育新的年轻工程师和科学家。

This Small Business Innovation Research (SBIR) Phase I aims to enable the widespread use of magnesium alloys in automobiles by developing a self-healing, chromate-free conversion coating for magnesium alloy components. The weight reduction associated with the use of magnesium will make automobiles more fuel-efficient and reduce CO2 emissions. A major impediment to the use of magnesium in automotive applications has been its high susceptibility to corrosion. Although chromate conversion coatings provide adequate corrosion inhibition, hexavalent chromium is a carcinogen. As a result, automotive manufacturers have resorted to using alternatives to chromate-based coatings. Commercial non-chrome pretreatments exhibit barrier properties, but do not provide adequate damage-response behavior, resulting in poor performance relative to chromate coatings. Hence, there is a need for a chrome-free pretreatment that displays damage-responsive corrosion behavior similar to that of chromates. The key innovation proposed in this research is the development of a novel non-chrome corrosion inhibiting pretreatment technology that is expected to impart self-healing behavior. If successful, it will set the stage for a phase II program, where tests will be conducted under simulated use conditions, leading to the fabrication and testing of prototype automotive components.The broader impact of this research will mainly be in the automotive applications, where the use of lighter-weight magnesium alloys (as compared to the currently used aluminum alloys) will help reduce CO2 emissions from the automobile exhaust. Currently some components (transmission housing and steering column) are made of magnesium alloys, but this research will permit the use of magnesium alloys for other components, such as engine blocks, gear boxes, clutch housing and engine cradle. This technology will also be applicable to aluminum alloys used in aerospace and underwater applications. The non-chromate technology will not only generate substantial revenue (estimated several million dollars) for the company, but will also help U.S. automotive manufacturers to provide lighter and more fuel-efficient cars for the overseas markets, especially in the European Union (EU). The work will be published in leading corrosion science journals and conferences, thereby providing new knowledge for the universities for the training and education of new, young engineers and scientists.