Effects of Gas Adsorption in Nano-asperity Tribological Contacts

美国宾夕法尼亚州立大学化学工程系金成H.固体表面吸附层的分子有序和厚度是表面科学与工程的核心问题。在之前的NSF项目（CMS-0408369）中，发现清洁氧化硅表面吸附水分子的结构有序对纳米粗糙接触的摩擦学性能起关键作用。利用醇的平衡吸附过程可以连续供给分子，形成几埃厚的醇膜，对纳米粗糙的氧化硅触点具有润滑作用。提出的研究目标是：(a)了解纳米摩擦学中气体吸附效应的基本原理；(b)开发用于微机电系统（MEMS）的气相润滑工艺。虽然本研究的主要焦点是固气界面的摩擦学特性，但从本研究中获得的基础知识将对纳米技术、生物材料、催化、环境科学等领域产生深远的影响，在这些领域，界面现象主导着系统的性能。本研究涵盖了从基础物理化学和热力学等科学基础到MEMS的工程应用；这将为参与该项目的学生提供多学科的培训。

CMS-0625493: Effects of Gas Adsorption in Nano-asperity Tribological ContactsSeong H. KimDepartment of Chemical Engineering, The Pennsylvania State UniversityThe molecular ordering and thickness of the adsorbed layer on solid is the core problem in surface science and engineering. In the previous NSF project (CMS-0408369), it is found that the structural ordering of the adsorbed water molecules on clean silicon oxide surfaces play key roles in tribological properties of the nano-asperity contact. It is also demonstrated that the equilibrium adsorption process of alcohol can be utilized for continuous supply of molecules to form a few Angstrom thick alcohol film which shows lubricating effects for nano-asperity silicon oxide contacts. The objectives of the proposed research are to (a) understand fundamentals of the gas adsorption effects in nanotribology and (b) develop the gas-phase lubrication process for applications to microelectromechanical systems (MEMS). Although the main focus of the proposed research is the tribological properties of the solid-gas interfaces, the fundamental knowledge attained from this research will have profound impacts on nanotechnology, biomaterials, catalysis, environmental science, etc. where interfacial phenomena dominate the system performances. This research covers from scientific fundamentals such as basic physical chemistry and thermodynamics to the engineering applications to MEMS; this will provide multi-disciplinary trainings to students involved in this project.