Lubrication by Chemical Reaction Products at Sliding Interface

机械的滑动和摩擦界面，无论是大的还是小的，都需要润滑来减轻摩擦和磨损，以便可靠地运行。否则，这些接口最终必然会失败。滑动界面的最后一道防护层是边界润滑层，它以化学或物理方式附着在固体表面上。这一层可以在机械装置装配和完全运行之前施加到摩擦学界面上，也可以在装置运行期间原位形成。这项工作的重点是在设备运行过程中，直接在滑动界面上原位合成边界润滑膜。本研究可以产生一种新型的润滑油添加剂，可以降低汽车行业的寄生摩擦能损失。这项工作还可以重振需要移动和滑动结构部件可靠操作的微型机电技术。该项目将培养具有多学科技能的学生，包括表面科学、分子表征和成像以及摩擦学；这些学生将为新兴的纳米工程领域以及传统的润滑行业做出实质性贡献。研究成果将被纳入研究生表面表征课程，并传播到广泛的科学和工程领域，包括化学、化学工程、机械工程、材料科学和摩擦学。机械性化学反应很容易在所有长度的尺度上发生；然而，控制反应产率和选择性的关键参数没有很好的记录或了解。本研究旨在从机理上加深对机械力化学反应的理解，这种化学反应可以产生可靠的边界润滑膜，并具有低界面剪切力和高承载能力等互补性能。要研究的两个特殊体系是：(I)从气相中吸附的不饱和醇酯的机械力化学聚合，以合成多元醇和聚酯的多层膜；(Ii)二茂铁催化润滑油中有机前体的机械力化学反应及其在滑动界面上的石墨化。这项工作将进行系统的研究，以了解接触压力、剪切速率、反应物分子结构和衬底材料的化学成分如何影响机械力化学反应的产率和选择性以及所产生的薄膜的润滑性能。这项研究成果不仅将在极端条件下的润滑表面工程方面取得突破，而且还将推进摩擦化学的基础知识，这些基础知识仍然是经验的和定性的。

Sliding and rubbing interfaces of machineries, whether they are big or small, need lubrication to mitigate friction and wear for reliable operation. Otherwise, these interfaces are bound to fail eventually. The last defense of the sliding interface from such failure is boundary lubrication layers which are chemically or physically adhered to solid surfaces. This layer can be applied to the tribological interface before the assembly and full operation of mechanical devices, or formed in-situ during the operation of the devices. This work focuses on in-situ synthesis of boundary lubrication films directly at the sliding interfaces during the device operation. This research can generate a new lubricant additive chemistry which can reduce parasitic frictional energy losses for automobile industries. This work could also revive the microscale electromechanical technology requiring reliable operations of moving and sliding structural components. This project will train students with multidisciplinary skills covering surface science, molecular characterization and imaging, and tribology; these students will make substantial contributions to newly emerging nano-engineering fields as well as traditional lubrication sectors. The research outcome will be incorporated into a graduate surface characterization course and disseminated through to a broad range of science and engineering fields covering chemistry, chemical engineering, mechanical engineering, materials science, and tribology.Mechanochemical reactions readily occur at all length scales; however, key parameters governing the reaction yield and selectivity are not well documented or understood. This study aims at advancing mechanistic understanding of mechanochemical reactions that can produce reliable boundary lubrication films with complementary properties such as low interfacial shear and high load-bearing. Two specific systems to be studied are (i) mechanochemical polymerization of unsaturated alcohols and esters adsorbed from the vapor phase for synthesis of multilayer films of polyols and polyolesters and (ii) ferrocene-catalyzed mechanochemical reactions of organic precursors in lubricant oils and their graphitization at the sliding interface. This work will undertake systematic studies to understand how contact pressure, shear rate, structure of reactant molecules, and chemistry of substrate materials affect the mechanochemical reaction yield and selectivity as well as the lubrication properties of the produced films. The outcome of this study will not only make breakthroughs in surface engineering for extreme-condition lubrications, but also advance fundamental knowledge of tribochemistry which is still empirical and qualitative.