A Direct Experimental Link Between Atomic-Scale and Macroscale Friction

摩擦力支配着几乎每台机器的操作限制、耐用性、能源消耗和控制，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，但众所周知，它起源于原子尺度。尽管科学上的根源可以追溯到达芬奇，但我们对这些基本的原子规模的相互作用如何导致日常摩擦的理解仍然很差。该奖项将支持对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。研究结果将被用于开发可测试的摩擦结垢模型。这样的模型对于摩擦控制应用中的材料设计和表面工程工作是必要的。我们将通过与工业合作伙伴的现有合作将成果转化为实践，这些合作伙伴的产品都广泛使用了这里研究的模型固体润滑剂材料。最后，该项目资助了一项面向6-12年级人群、大学生和教职员工以及更广泛的科学界的教育努力。原子力显微镜能够对原子尺度的摩擦现象进行基础研究，而传统的摩擦计量学则在更实际的宏观尺度上测量摩擦。由于缺乏研究长度、力和速度范围所需的工具，社区无法将机器摩擦与其根本根源联系起来。该项目的团队开发了两项关键技术来实现这一项目：1)可靠地校准和定量测量原子尺度的摩擦的方法；2)能够将原子尺度的测量与宏观尺度的测量联系起来的微型摩擦测量仪。该项目的目标是通过在原子尺度和宏观尺度之间仔细控制材料、载荷、探测器半径和速度，将这些长度尺度缝合在一起。结果将用于开发界面摩擦的可测试比例模型，使我们的材料科学家合作者能够设计材料和设计界面，以改进摩擦控制。为了将科学翻译给更广泛的受众，该团队将：1)在最引人注目的期刊上发表文章；2)出席影响较大的会议；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；以及6)通过在校园和摩擦学会议上开展外联活动，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.