石墨烯润滑膜层间结构与作用力的润滑机理与可控成形方法

Existing solid lubricants such as diamond-like carbon and MoS2 are hard to be applied in harsh working conditions such as high temperature, etc. Graphene has been proved to have nano-scale super-lubricating property and good high-temperature stability; hence, it is considered as one of the most promising solid lubricants in future. However, the contact area of frictional parts is much larger than nanometers, and the graphene lubrication film is easily worn out after a long service. How to process a large-area high-performance graphene lubricating film is the key issue for its application. In many past studies, the graphene lubrication performance was shown to strongly depend on the interlayer structure and interactions..Here, in this project the influence of graphene interlayer interaction on the tribological behavior will be firstly studied by simulation to unveil the lubrication mechanism. Next, based on the simulation results, chemical modification of graphene sheets will be adopted to control the interlayer interaction. Then, a new electromagnetic-field assisted fabrication method will be used to fabricate large area graphene lubrication film, in which graphene orientation and distribution can be controlled depending on the graphene magnetization/polarization and uniform property of the electromagnetic field. Thus a large graphene lubricating film with a uniform, continuous and orientated interlayer structure and tailored interlayer interaction will be obtained; Finally, characterization and high-temperature friction tests will be conducted to verify the film structure and lubrication mechanism. If the project succeeds, it will provide a feasible way for fabricating high-performance graphene lubrication films under extreme servicing conditions, such as high temperature

现有的类金刚石碳、硫化钼等固体润滑剂在高温等极端工况下难以适用，石墨烯已被证实具有纳米尺度下超润滑特性及高温惰性，被认为是未来最有潜力的固体润滑材料之一。然而实际工况下零部件接触面积远大于纳米尺度且目前石墨烯润滑膜易损耗，如何制备成形大面积高性能润滑膜仍是制约其应用的瓶颈。基于已有研究，石墨烯层间结构和层间作用力被认为是影响润滑性能的关键因素。.因此，本项目首先借助模拟仿真研究石墨烯层间作用力对润滑性能的影响规律和润滑机理；在此基础上利用化学改性调控石墨烯层间作用力，并提出电磁辅助成形大面积润滑膜新工艺，利用石墨烯磁化极化效应和电磁场均匀连续性控制石墨烯取向和均匀连续分布；试图制造出兼具均匀连续取向的层间结构且层间作用力可控的石墨烯润滑膜；最后通过高温实验测试验证石墨烯润滑膜成形工艺和润滑机理。项目成功后，可为高性能石墨烯润滑膜加工成形提供一种可行途径，对高温等极端工况下润滑具有重要意义。

本项目针对石墨烯层间作用力及其超润滑特性，开展了多层石墨烯层间作用力、石墨烯固体润滑性能、及石墨烯改性涂层/复材的润滑耐磨性能方面的研究，并基于多层石墨烯层间滑移特性，进一步扩展应用至复合材料阻尼领域。具体研究如下。.1 设计双层石墨烯面内拉伸微型实验装置，在线观察双层石墨烯边界距离随基底拉伸的变化，同时结合有限元分析，剖析石墨烯界面未脱粘、部分脱粘、面内滑移、石墨烯面内失效等情况。分析得石墨烯层间界面刚度1×102 MPa/mm。该课题宏观分析可与现有诸多微纳尺寸研究形成互补，对石墨烯润滑等实际应用奠定理论基础。.2 分析石墨烯及石墨纳米粉在不同压力和速度下的润滑效果，获得了超低摩擦系数0.03，且数据表明石墨烯对正压力敏感，对摩擦速度不敏感，而石墨与之相反相反。表征结果表明石墨烯被压实后片与片之间相连，形成了完整的润滑膜。同时，实验表明石墨烯片剪切应力0.4MPa，与诸多文献报道的微观实验结果相当接近。该课题实验结果对石墨烯固体润滑剂的应用具有很好的指导意义。.3 将三维石墨烯改性环氧涂层，与石墨形成多尺度的三维结构，可显著提高涂层的耐磨润滑及导热性能，摩擦系数由1.10降至0.51，磨损量63.7×10-6降低至4.1×10-6。表征结果证实石墨烯与石墨剥落在摩擦面上形成完整的润滑膜，进而显著提高复材的耐磨润滑性能。该实验不仅证实了本课题大面积石墨烯膜润滑效果，并拓展了润滑领域的应用。.4 通过电泳方法，成功在金属基底、碳纤维布等基体表面沉积宏观尺度石墨烯膜。并结合石墨烯层间滑移特性，将应用进一步拓展至复合材料阻尼领域。阻尼测试结果表明在宽温度/频率/应变扫描模式下，石墨烯均可明显提高复合材料的阻尼特性；同时通过限元分析可得到多层石墨烯层间属性，杨氏模量1GPa，阻尼损耗因子0.20。