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

小型企业创新研究(SBIR)第一阶段旨在通过开发镁合金部件的自愈性、无铬转化涂层，使镁合金在汽车上得到广泛使用。与使用镁相关的重量减轻将使汽车更省油，并减少二氧化碳排放。镁在汽车应用中使用的一个主要障碍是它对腐蚀的高度敏感性。虽然铬酸盐转化膜提供了足够的缓蚀作用，但六价铬是一种致癌物质。因此，汽车制造商已经求助于使用铬酸盐涂料的替代品。商用非铬前处理具有阻隔性能，但不能提供足够的损伤响应行为，导致与铬酸盐涂层相比性能较差。因此，需要一种无铬前处理，其表现出与铬酸盐类似的损伤响应腐蚀行为。本研究提出的关键创新是开发了一种新型的无铬缓蚀预处理技术，有望实现自愈行为。如果成功，它将为第二阶段计划奠定基础，该计划将在模拟使用条件下进行测试，导致原型汽车零部件的制造和测试。这项研究的更广泛影响将主要在汽车应用中，使用更轻的镁合金(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(变速箱壳体和转向柱)是由镁合金制成的，但这项研究将允许将镁合金用于其他部件，如发动机机体、变速箱、离合器壳体和发动机底座。这项技术也将适用于航空航天和水下应用中的铝合金。这项非铬酸盐技术不仅将为该公司带来可观的收入(估计为数百万美元)，还将帮助美国汽车制造商为海外市场提供更轻、更省油的汽车，特别是在欧盟(EU)。这项工作将发表在领先的腐蚀科学期刊和会议上，从而为大学培训和教育新的年轻工程师和科学家提供新的知识。

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.