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

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.