石墨烯/纳米颗粒新型复合结构调控原理及润滑机理研究

Metal-based nanoparticles and two-dimensional graphene nanosheets as lubricant additives show significant meaning for study and application, because of their unique surface interface effects, high thermal conductivities and excellent mechanical properties. However, the tribological properties of the additives are faced with severe challenges under extreme conditions of high temperature and high load: the nanoparticles are prone to being agglomeration and precipitation due to high surface activity; Friction-induced structural defects of graphene results in unstable tribofilm. Taking the advantages of the nanoparticles and graphene, this project aims to green in-site synthesis of graphene-based lubricant additives: to propose the new ideas and methods of the nucleation and grown of nanoparticles simultaneously on graphene surfaces and between their layers, and to obtain the new structure and system of "sheet/particle" nanocomposite lubricant additive. This project firstly investigates the inhibitory effect of compound effect on the agglomeration of the lubricant additives, secondly study the tribological properties of the additives when the reduction and exfoliation degree of graphene and physical and chemical structure of nanoparticles change, thirdly analyze the contribution of the graphene and the nanoparticles respectively to the anti-friction and anti-wear resistance under the extreme conditions, and then reveal the lubrication mechanism of graphene interlayer sliding and nanoparticle micro-rolling effects and further establish a "slide-roll" synergistic coupling lubrication model, finally solve the scientific problems of severe agglomeration and unstable tribofilm and overcome the failure bottleneck of the tribological properties under the extreme conditions.

金属基纳米颗粒和二维石墨烯纳米片具有独特表界面效应、极高导热性能和优异力学特性，作为润滑添加剂的研究和应用具有重大意义。然而，在高温重载极端工况下，其摩擦学性能受到严峻挑战：高表面活性促使纳米颗粒相互团聚沉淀；摩擦诱发石墨烯结构缺陷导致成膜性能不稳定。本项目结合纳米颗粒和石墨烯各自摩擦学特性优势，绿色原位制备调控石墨烯纳米复合润滑添加剂：提出纳米颗粒在石墨烯表面和层间并行成核生长新思路和新方法，获得纳米润滑添加剂“薄片/颗粒”复合新结构和新体系。考察复合效应对纳米润滑添加剂团聚抑制作用，研究石墨烯还原剥离程度和纳米颗粒物理化学结构对摩擦学性能影响规律，解析极端工况下二者对减摩性能和耐磨性能各自贡献，揭示石墨烯层间滑动效应和纳米颗粒微滚动作用机制，构建石墨烯纳米复合润滑添加剂“滑-滚”协同润滑模型，解决纳米润滑添加剂团聚和成膜性能不稳定科学问题，从而突破其在极端工况下摩擦学性能失效瓶颈。

在高温重载极端工况下，零维纳米润滑颗粒和二维石墨烯纳米片摩擦学性能受到严峻挑战：高表面活性促使纳米颗粒相互团聚沉淀；摩擦诱发石墨烯结构缺陷导致边界润滑膜磨损失效。申请人在自然科学基金青年基金的资助下，结合石墨烯和纳米颗粒各自摩擦学特性优势，提出了纳米润滑颗粒的原位均质复合调控思想，发明了绿色原位制备石墨烯/颗粒纳米复合润滑颗粒方法；探究其微结构演变规律与摩擦学性能构效关系，获得了耐高温重载纳米润滑油脂及其复配工艺；揭示石墨烯和纳米颗粒协同润滑机制，建立了润滑颗粒的层间滑移及“滑-滚”协同润滑模型。同时取得了一系列成果，包括：发明了石墨烯纳米复合润滑颗粒微结构调控新方法新体系，揭示了摩擦诱导作用下纳米润滑颗粒界面演化机制，解释了纳米流体边界润滑膜与动压润滑膜“固-液”耦合效应，建立了石墨烯纳米复合颗粒边界膜的“滑-滚”协同润滑模型，克服了润滑颗粒高温团聚和成膜性能不稳定关键问题，获得了高温（125℃）“近零磨损”耐磨特性。自主研发石墨烯航空润滑脂将航空作动器电机的启动电流降低33.8%，电机动子滑动行程增大4.1-37.0%。基于以上成果，申请人在ACS Nano，Nano-Micro Letters，Chemical Engineering Journal等期刊发表研究论文18篇，其中第一作者及通讯作者SCI论文15篇，包括5篇期刊封面论文，授权发明专利1项，出版学术专著1部，参加学术会议4次。