Collaborative Research: Quantitative Prediction of Sliding Friction Using Integrated Theory and Experiments

本研究旨在对模型边界膜的能量耗散、界面结构和摩擦力进行定量研究。 虽然迄今为止的理论方法已经能够提供定性的见解滑动摩擦，他们还没有能够定量地描述的结构的滑动界面和相关的摩擦力。 本研究的方法将是联合收割机实验在真空中定义良好的模型边界膜组成的一系列的同构碱金属卤化物的金属基板与分子动力学模拟使用定制的，高精度的相互作用势从密度泛函理论计算相同的系统。 如果成功的话，这项研究的好处将包括了解边界膜的摩擦性能，这些边界膜是由润滑剂添加剂或气相润滑剂在滑动的固-固界面处的化学反应形成的。 这一基本认识将有助于设计有效的润滑剂，形成低摩擦或磨损的薄膜，从而节省能源和延长机器寿命，并使美国受益。经济 此外，理解滑动摩擦提出了一个独特的实验挑战，因为该过程发生在一个不可接近的，滑动的固体-固体界面，不能直接询问。 这意味着理解这些界面的进展将依赖于在相同系统上进行的实验和理论方法的整合。 能够实现这一点的简单系统中探索的建议将开发理解更复杂的滑动界面的理论和实验策略。 最后，综合实验和理论方法将为学生提供基础广泛的教育，并将涉及本科生和代表性不足的少数民族。 在过去的几十年里，理论方法的发展和实验方法的改进导致了科学研究方式的根本转变，这将需要将理论和实验相结合的研究生和本科教育。 这一点在最近一期的《摩擦学快报》中得到了强调，这一期由该提案的主要研究者共同编辑，标题为？模拟与实验相结合的摩擦学研究进展。

This research is about obtaining a quantitative understanding of energy dissipation, interfacial structure and friction of model boundary films. While theoretical methods have hitherto been able to provide qualitative insights into sliding friction, they have not yet been able to quantitatively describe the structure of a sliding interface and the associated friction forces. The approach of this research will be to combine experiments in ultrahigh vacuum on well-defined model boundary films consisting of a range of isostructural alkali halides on metal substrates with molecular dynamics simulations using tailored, high-precision interaction potentials obtained from density function theory calculations of the same systems. If successful, the benefits of this research will include an understanding of the friction properties of the boundary films that are formed by chemical reactions between lubricant additives or gas-phase lubricants at a sliding, solid-solid interface. This fundamental understanding will underpin efforts to design effective lubricants that form films with low friction or wear, thereby resulting in energy savings and longer machine lifetimes, and benefit the United States? economy. In addition, understanding sliding friction poses a unique experimental challenge because the processes occur at an inaccessible, sliding solid-solid interface that cannot be interrogated directly. This means that advances in understanding such interfaces will rely on integrating experiments and theoretical methods carried out on the same systems. Being able to achieve this for the simple systems explored in this proposal will develop the theoretical and experimental strategies for understanding more complex sliding interfaces. Finally, the integrated experimental and theoretical approaches will provide a broad-based education for students and will involve both undergraduates and under-represented minorities. Developments in theoretical methods and the refinement of experimental approaches over the past few decades have resulted in a fundamental shift in the way that science is carried out and will require both graduate and undergraduate education that integrates theory and experiment. This has been emphasized in a recent special issue of Tribology Letters co-edited by the Principal Investigators of this proposal entitled ?Progress in Tribology Through Integrated Simulations and Experiments?.