Cost-effective and Environmentally-friendly Manufacturing of Magnesium-based Hybrid Nanocomposite with High Engineering Performance for Next-Generation Automotive Applications

在过去的二十年里，由于镁的重量轻，它在汽车中的使用量显著增加。从工程性能的角度来看，镁合金的机械性能、高温性能、腐蚀性能和磨损性能与铝合金和钢相比，并不具有很强的竞争力。近年来的研究表明，纳米级增强剂的加入在不显著影响镁塑性的情况下提高了镁的力学性能。然而，将纳米复合材料应用于实际工程应用，特别是汽车零部件，正面临挑战，而且仍处于起步阶段，因为纳米颗粒的高成本和实验制备过程的复杂性使它们对竞争激烈的汽车工业的吸引力不如微尺寸增强和传统方法，即搅拌铸造和/或预成型和挤压铸造。该研究项目的总体目标是开发具有高工程性能的镁基混合纳米复合材料（MHNC）的成本效益和环境友好型制造工艺，以便汽车工业在下一代结构和动力系统应用中充分利用其独特的性能，这些应用不仅需要承受高循环机械载荷，而且需要在使用期间承受恶劣和腐蚀的环境。在提议的方案中，规划了两条相互交织的溪流。首先，通过开发预挤压铸造技术，适当选择微米和纳米尺寸的增强材料，以及对加工-结构-性能关系的综合评估，来制造MHNCs。该研究计划的第二部分将寻求利用等离子体电解氧化（PEO）工艺的优势，并将其应用于镁基混合复合材料的防腐和磨损保护。

Magnesium usage has significantly increased in vehicles for the past two decades due to its light weight in nature. From the viewpoint of engineering performance, magnesium alloys are not very competitive owing to their inferior mechanical and high-temperature and corrosion and wear properties in comparison with aluminum alloys and steels. Recent studies show that the addition of nanosize reinforcements enhances the mechanical properties without substantially affecting the plasticity of magnesium. However, applying the nanocomposites for real engineering applications, especially automotive components, is facing challenges and still in infancy because the high cost of nanoparticles and the complexity of experimental preparation processes make them less attractive to the highly competitive automotive industry than micro-size reinforcement and conventional approaches, i.e., stir casting and/or preform and squeeze casting. The overall objective of this research program is to develop cost-effective and environmentally-friendly manufacturing processes for fabrication of magnesium-based hybrid nanocomposite (MHNC) with high engineering performance in order for the automotive industry to make full use of their unique properties in next-generation structural and powertrain applications, which not only suffer high cyclic mechanical loading but also need to sustain harsh and corrosive environment during service. In the proposed program, two intertwined streams are planned. The first involves the fabrication of MHNCs by developing preform-squeeze casting technologies with appropriate selection of micron and nano-size reinforcements, and a comprehensive evaluation of processing-structure-property relationships. A second stream within this program of research will seek to exploit the advantages of the Plasma Electrolytic Oxidation (PEO) process and apply it to the magnesium-based hybrid composites for anti-corrosion and wear protection. The outcome of the project will maintain Canada as a world leader in producing light weight magnesium-based engineering components since Canada is presently hosting the largest magnesium casting producer in the world, Meridian Lightweight Technologies in Ontario. The success in the development of new technologies for potential advanced components will lead to an increase in magnesium component shipment in Canada as well as an expansion of world-wide use of Canadian value-added magnesium products.