CAREER: Lamellar Lubricity - Linking Structure, Properties and Tribological Performance of Molybdenum Disulphide

这项学院早期职业发展(Career)计划拨款支持对重要的干式、非油基、固体润滑剂材料的摩擦和磨损过程的基础研究，这些材料对于在恶劣环境(包括太空)中的使用至关重要。这项工作有助于增进我们对润滑机理的科学认识，有助于干式润滑剂的进一步发展。这些润滑剂对我们的国防和繁荣至关重要，因为它们影响了许多商业应用，在这些应用中，润滑性差会导致磨损，从而限制机器的使用寿命并浪费能源。这项研究将使用原子级工具来了解这些干润滑剂的表面结构，重点是二硫化钼，它是使用中最重要的干润滑剂。这种润滑剂由于在MoS2内形成缺陷和缺陷结构而不能使用。为了确定这种缺陷结构的演变，样品将在实验室中进行受控磨损，或者将长期暴露在国际空间站(空间站)的空间环境中。摩擦和润滑性能的变化以及原子级结构将被确定。这些信息将产生对缺陷形成过程的基本了解，有助于设计在所有环境中都具有更长使用寿命的新型润滑剂和添加剂。推广和教育特色包括一个综合的研究/教育计划，以增加社会各阶层对摩擦学的教育、接触和兴趣，并通过亲身实践的K-12扩展活动、课程开发以及学生本科生和研究生的研究经验。实验、先进的表征和模型将探索极端环境(包括空间)下MoS2涂层的结构、工艺、性能和摩擦学性能之间的联系。该技术计划以两个研究主题为中心：1)评估二硫化钼的微观结构和成分在防止在氧化和潮湿环境中暴露时的化学和摩擦学退化方面的作用；2)了解MoS2摩擦学的能量学，以开发一个摩擦模型，该模型基于在滑动过程中形成的摩擦膜的取向、公度、缺陷密度和微晶尺寸随温度、环境和开始/演变的微观结构的函数。将对不同微观结构、成分和加工工艺的MoS2薄膜进行系统的测试，以开发MoS2摩擦学相互作用的机理框架。实验包括环境摩擦学研究，通过最先进的表面化学表征和原子分子动力学模型，寻找超高真空、湿度、O2、原子氧和极端温度的影响。最后，将对国际空间站返回的摩擦学实验和材料样本进行分析。这一裁决反映了NSF的法定任务，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This Faculty Early Career Development (CAREER) Program grant supports fundamental studies of the friction and wear processes of the important dry, non-oil-based, solid lubricant materials that are critical for use in harsh environments, including space. The work serves to promote our scientific base of understanding of the mechanism of lubrication aiding in the further development of dry lubricants. These lubricants are critical to our national defense and prosperity by impacting the many commercial applications where poor lubrication can lead to wear that limits the machine lifetime and wastes energy. The research will use atom-level tools to understand surface structure of these dry lubricants, with an emphasis on MoS2 which is the most important dry lubricants in use. This lubricant fails in use through the development of defects and a defect structure within the MoS2. To determine the evolution of this defect structure, samples will undergoing controlled wear in the laboratory or will have been exposed to the environment of space on the international space station (ISS) for an extended time. The changes in friction and lubricating properties together with the atomic level structure will be ascertained. This information will generate the basic understanding of the defect formation process aiding in the design of new lubricants and additives with extended lifetime in all environments. The outreach and education features include an integrated research/education plan to increase education, exposure and interest in tribology at all levels of society, with hands-on K-12 outreach activities, curriculum development, and student undergraduate and graduate research experiences.Experiments, advanced characterization and models will probe the links between structure, processing, properties and tribological performance of MoS2 coatings for extreme environments (including space). The technical program is centered 2 research themes: 1) assess the role of molybdenum disulphide microstructure and composition in preventing chemical and tribological degradation during exposure to oxidative and humid environments; 2) understand the energetics of MoS2 tribology to develop a model of friction based on orientation, commensurability, defect density and crystallite size as a function of temperature, environment and starting/evolving microstructure of tribofilms formed during sliding. MoS2 films of varying microstructure, composition and processing techniques will be systematically tested to develop a mechanistic framework for tribological interactions of MoS2. Experiments include environmental tribological studies looking to the effects of ultrahigh vacuum, humidity, O2, atomic oxygen and temperature extremes through state-of-the-art surface chemical characterization and atomistic molecular dynamics models. Finally, tribological experiments and material samples returned from the international space station will be analyzed.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.