Solid lubrication by carbon nanotubes: Understanding transfer layer formation and sliding at a fundamental level using atomistic simulations and experimental nano analytics

摩擦和磨损造成了巨大的成本，约占高度工业化国家国内生产总值的5%。同时，出于环境原因以及为了减少对化石油资源的依赖，人们做出了许多努力来将液体润滑剂改变为固体润滑剂。然而，目前固体润滑剂仅应用于液体润滑失效的地方。这是在极端条件下的情况，如在真空中，在高温，压力和滑动速度。因此，进一步开发和设计固体润滑系统，特别是在高机械载荷下的固体润滑系统，具有很高的技术相关性。碳纳米管（CNTs）是由碳原子制成的圆柱形纳米结构，具有优异的机械、物理和化学性能，是与石墨或石墨烯密切相关的一类材料。与精心准备和结构化的摩擦表面结合，它们可以作为高效和耐用的固体润滑剂。另一方面，决定碳纳米管的摩擦学行为的微观机制知之甚少。主要的未回答的问题涉及摩擦和转移层的形成，润滑过程和机械和摩擦化学负载下的碳纳米管的降解。因此，CNT润滑的受控设计需要进一步的研究activitites。本研究提案的目标是在微观水平上更深入地了解摩擦力学和摩擦化学方面。我们的研究成果将用于开发高机械负荷下球轴承目标应用的设计规则。这意味着我们必须找出哪些参数一方面决定了转移层的形成，另一方面决定了摩擦的减少。该研究方案将原子模拟与摩擦学实验以及物理和化学分析相结合。

Friction and wear cause tremendous costs which amount to about 5 % of the gross domestic product of highly industrialized countries. At the same time, there are many efforts to change from liquid to solid lubricants for environmental reasons and in order to reduce the dependence on fosil oil resources. However, at the moment solid lubricants are only applied where liquid lubrication fails. This is the case under extreme conditions as in vacuum, at high temperatures, pressures and sliding velocities. The further development and design of solid lubrication systems especially also under high mechanical loading is thus of high technological relevance.Carbon nanotubes (CNTs) are cylindrical nano structures made from carbon Atoms with excellent mechanical, physical and chemical properties and are as a materials class closely related to graphite or graphene. In combination with well prepared and structured tribo surfaces they can act as highly efficient and durable solid lubricants. On the other side, the microscopic mechanisms determining the tribological behaviour of CNTs is only poorly understood. The main unanswered questions concern the formation of tribo- and transfer layers, the lubrication processes and the Degradation of CNTs under mechanical and tribochemical loading. The controlled design of CNT lubrication therefore requires further Research activitites.Goal of this research proposal is a more in-depth understanding of the tribomechanical and tribochemical aspects at the microscopic level. The outcome of our research will be used to develop design rules for the target application of ball bearings under high mechanical loading. That means we have to find out which parameter determine the formation of transfer layers on one hand and the friction reduction on the other.The research proposal combines atomistic simulations with tribological experiments and physical as well as chemical analytics.