Novel Corrosion Control of Mg Alloys in Structural Lightweight Multi-Materials Assemblies

通过使用坚固的轻质材料来减少运输车辆的总质量可以说是提高燃料效率的最佳手段，从而减少有害排放。锻造ZE（Zn-Zr-稀土）镁合金具有高的比强度、刚度和热成形性，可作为轻质多材料结构组件的组成部分，实现这一目标。阻止镁合金部件广泛应用的一个关键技术问题是在水性环境中的高溶解速率（腐蚀）。这在很大程度上是由Mg的固有反应性（工业工程金属中最低的标准还原电位）、主导阴极过程的析氢反应的高速率以及天然氧化物表面膜破裂并被显著更厚且保护性更低的腐蚀产物膜替代的趋势驱动的。我的研究计划的长期目标是开发一个基础知识库，使结构轻质多材料组件的制造包括新兴的先进材料和工艺（连接和表面处理），具有更好的耐用性（腐蚀和疲劳），这刺激了加拿大制造的独创性，以支持全球运输业。一个综合的目标是提供一个包容性的多学科（电化学，表面科学和物理冶金）的研究栖息地，将教育和培训加拿大的下一代HQP谁将推动开发和实施创新的腐蚀控制解决方案的强大的轻质材料。基于我最近的研究进展，下一个研究计划的里程碑是开发一个使能知识库，该知识库将支持ZE镁合金在轻质多材料组件中的成功部署，使用新方法改善腐蚀控制。具体的短期目标包括：（i）开发由Li 2CO 3转化涂层组成的新型电涂涂层方案，（预处理）能够封闭愈合缺陷部位，（ii）开发一种新的再填充搅拌摩擦点焊连接技术，其机械地结合无毒阴极动力学抑制剂以控制焊缝的腐蚀，以及（iii）证明了通过两种提出的创新的组合实现的改进的腐蚀控制：具有与涂覆的铝合金所表现出的类似程度的腐蚀控制的坚固的轻质涂覆的ZE镁合金接头。三名HQP将在本研究计划中接受教育和培训：两名博士生和一名MASc学生。

Reducing the overall mass of transportation vehicles by the use of strong lightweight materials is arguably the best enabling means to improve fuel efficiency and, thus reduce harmful emissions. Wrought ZE (Zn-Zr-rare earth) Mg alloys with high specific strength, stiffness and warm formability provide enabling opportunities as an integral part of lightweight multi-material structural assemblies to achieve this goal. One key technical issue preventing widespread implementation of Mg alloy components is the high rate of dissolution (corrosion) in aqueous environments. This is driven in large part by the inherent reactivity of Mg (lowest standard reduction potential among industrial engineering metals), the high rate of the hydrogen evolution reaction that dominates the cathodic process and the tendency of the native oxide surface film to breakdown and be replaced with a significantly thicker and much less protective corrosion product film. The long-term goal of my research program is to develop a fundamental knowledge base that enables fabrication of structural lightweight multi-materials assemblies comprised of emerging advanced materials and processes (joining and surface treatment) with improved durability (corrosion and fatigue) that spurs a made-in-Canadian ingenuity to support the global transportation industry. An integrated goal is to provide an inclusive multi-disciplinary (electrochemistry, surface science and physical metallurgy) research habitat that will educate and train Canada's next generation HQP whom will drive development and implementation of innovative corrosion control solutions for strong lightweight materials. Building upon my recent research progress, the next research program milestone is to develop an enabling knowledge base that will underpin successful deployment of ZE Mg alloy in lightweight multi-material assemblies using novel approaches for improved corrosion control. Specific short-term goals include: (i) develop a novel electro-coat coating scheme comprised of a Li2CO3 conversion coating (pre-treatment) that is capable of seal-healing defects sites, (ii) develop a novel refill friction stir spot welding joining technology that mechanically incorporates a non-toxic cathode kinetics inhibitor to control corrosion of the weld and (iii) demonstrate the improved corrosion control achieved through combination of the two proposed innovations: strong lightweight coated ZE Mg alloy joints with a similar extent of corrosion control exhibited by coated Al alloys. Three HQP will be educated and trained in this research proposal: two PhD level students and one MASc level student.