A Direct Experimental Link Between Atomic-Scale and Macroscale Friction

摩擦控制着几乎所有机器的运行限制、耐用性、能耗和控制，包括那些对医疗保健、经济繁荣和国家安全具有重要影响的机器。虽然我们在宏观尺度上感觉到摩擦，但我们知道它起源于原子尺度。尽管科学根源可以追溯到达芬奇，但我们对这些基本的原子尺度相互作用如何导致日常摩擦的理解仍然很差。该奖项将支持从原子尺度到实际尺度的界面摩擦的受控研究，以阐明这种关系。研究结果将用于开发一个可测试的摩擦结垢模型。需要这样的模型来通知摩擦控制应用的材料设计和表面工程工作。 这些结果将通过我们与工业合作伙伴的现有合作转化为实践，这些合作伙伴的产品都广泛使用了本文研究的模型固体润滑剂材料。最后，该项目资助一项教育工作，覆盖6- 12年级人口、大学生和教职员工以及更广泛的科学界。原子力显微镜能够对原子尺度的摩擦现象进行基础研究，而传统的摩擦测量法则在更实际的宏观尺度上测量摩擦。由于缺乏研究两者之间的长度、力和速度尺度所需的工具，人们无法将机器摩擦与其根本起源联系起来。 该项目的团队开发了两项关键技术来实现该项目：1）可靠校准和定量测量原子尺度摩擦的方法，2）能够将原子尺度测量与宏观尺度测量相结合的微摩擦计。 本项目的目标是通过仔细控制材料、载荷、探针半径和速度，在原子尺度和宏观尺度之间的差距中，将这些长度尺度缝合在一起。 研究结果将用于开发界面摩擦的可测试缩放模型，使我们的材料科学家合作者能够设计材料和工程界面，以改善摩擦控制。 为了促进科学翻译到更广泛的受众，该团队将：1）在最知名的期刊上发表; 2）出席高影响力的会议; 3）教育合作者; 4）将实践和成果注入教学; 5）指导研究生和本科生进行研究;和6）通过在校园和摩擦学会议上开展外展活动来吸引7- 12年级的人群。

Friction governs the operating limitations, durability, energy consumption, and control of virtually every machine including those with important implications for healthcare, economic prosperity, and national security. Although we sense friction at the macroscale, it is known to originate at the atomic-scale. Despite having scientific roots dating back to da Vinci, our understanding of how these fundamental atomic-scale interactions contribute to everyday friction remains poor. This award will support a controlled study of interfacial friction from the atomic-scale to the practical-scale to elucidate this relationship. The results will be used to develop a testable model of frictional scaling. Such a model is needed to inform materials design and surface engineering efforts for friction control applications. The results will translate to practice through our existing collaborations with industrial partners whose products all make extensive use of the model solid lubricant material studied here. Lastly, the project funds an educational effort that reaches 6-12th grade populations, university students and faculty, and the broader scientific community. Atomic force microscopy enables fundamental studies of atomic-scale friction phenomena whereas traditional tribometry measures friction at the more practical macro-scale. A lack of the tools needed to study the length, force, and speed scales in between has prevented the community from linking machine friction to its fundamental origins. The team on this project has developed two key technologies to enable this project: 1) a method to reliably calibrate and quantitatively measure atomic-scale friction and 2) a microtribometer capable of bridging measurements from the atomic-scale to those from the macroscale. The objective of this project is to stitch these length-scales together by carefully controlling material, load, probe radius and speed in the gap between the atomic and macro size-scales. The results will be used to develop a testable scaling model for interfacial friction that will enable our materials scientist collaborators to design materials and engineer interfaces for improved frictional control. To promote translation of the science to broader audiences, the team will: 1) publish in the most visible journals; 2) present at high impact conferences; 3) educate collaborators; 4) inject practices and outcomes into instruction; 5) mentor graduate and undergraduate students in research; and 6) engage 7-12th grade populations by conducting outreach activities on campus and at tribology conferences.