镁合金表面石墨烯涂层的构筑机制及耐蚀/耐磨一体化研究

Graphene, a new class of two-dimensional carbon nanostructure, has a great potential application in the surface treatment of Mg alloy, due to its high hardness, high modulus, and low friction coefficient. The poor corrosion and wear resistances of Mg alloy can be improved via the application of graphene materials, which will be benefit to the automotive lightweighting, and reducing the oil consumption and haze pollution. Unfortunately, the interface bonding between the graphene coating and Mg surface is very weak, because of the chemical inertness of graphene, which hinders its application. Therefore, in order to conquer the restriction of pure graphene material with high chemical inertness, the graphene oxide with superior chemical activity will be selected as a precursor in the current study. A functionalized graphene coating can be covalently bonded to the surface of Mg alloy, via chemical reduction and rare-earth-doped silane coupling agent. The main purpose of this study is to improve the bond strength and demonstrate the construction mechanism between the graphene coating and Mg alloy. The effects of rare-earth doping, the reduction, concentration of graphene oxide dispersion and pH value on the microstructure, corrosion and fraction/wear behavior of graphene coatings, will be systematically investigated. The bonding mechanism and the essential roles of intrinsic property/internal structure of graphene coating on the integrated anti-corrosive/wearable properties of Mg alloy will be clarified, which can provide the theoretical basis and technical support for the development of novel surface treatment technology of Mg alloy in the interdisciplinary field of material science and chemical science.

新型二维纳米材料石墨烯以高硬度、高模量及低摩擦系数等优点，在镁合金表面处理领域具有极大的应用潜力，有望解决镁合金中普遍存在的耐蚀、耐磨性差问题，对实现汽车材料轻量化、减轻油耗及雾霾污染等有着积极的意义。然而，惰性结构的石墨烯很难与镁合金形成良好的界面结合，限制了其在镁合金表面处理中的应用。本项目突破了理想石墨烯材料的化学惰性壁垒，拟采用高活性的氧化石墨烯为前驱体，结合化学还原调控技术，以稀土掺杂硅烷作为过渡层，设计出一种与镁合金表面以共价键结合的功能化石墨烯涂层，重点解决二者之间的结合强度及构筑机制问题。通过系统地研究稀土掺杂、氧化石墨烯还原、浓度、pH值等对涂层组织、腐蚀、摩擦磨损行为的影响规律，揭示石墨烯涂层与镁合金的键合反应机理，从石墨烯的本征属性/涂层结构角度，阐明其在实现镁合金耐蚀/耐磨一体化中的本质作用，为材料/化学交叉领域中的镁合金表面处理新技术开发提供理论依据和技术支持。

新型二维纳米材料石墨烯以高硬度、高模量及低摩擦系数等优点，在镁合金表面处理领域具有极大的应用潜力，有望解决镁合金中普遍存在的耐蚀、耐磨性差问题，对实现汽车材料轻量化、节能减排和可持续发展有着积极的意义。针对惰性较高的理想石墨烯材料难以与镁合金表面形成良好的界面结合问题，本项目采用高活性的氧化石墨烯为前驱体，通过碱性化学还原调控技术，结合多种高活性硅烷过渡层设计（如APTES，BTSE等），在镁合金表面成功制备出高质量的石墨烯超薄涂层。系统地研究了基团类型、氧化石墨烯的还原程度/浓度以及pH值等对涂层显微组织以及耐蚀、耐磨性能的影响规律，揭示了硅烷过渡层的“双亲分子桥”效应在提升镁合金与石墨烯片结合强度中的本质作用及涂层的构筑原理；以本征属性/微观结构的耦合调控为导向，阐明了镁合金表面新型石墨烯涂层的耐蚀/耐磨一体化机制，为材料/化学交叉领域中的金属表面防护技术开发提供理论依据和技术支持。