Environmental Sensitivity of Diamond-Like Carbon (DLC) Friction and Wear

该奖项的研究目标是了解和控制类金刚石碳(DLC)的表面性质，类金刚石碳是一种重要的技术材料。由于其优异的机械和摩擦学性能，各种类型的类金刚石在工程应用中被广泛用于控制摩擦和磨损。最近发现的氢化类金刚石薄膜的近乎无摩擦的特性可以带来减少摩擦能量损失和提高机械系统使用寿命的创新。然而，只有在初始诱导期之后，才能在真空或极端干燥的条件下观察到接近无摩擦的行为，在此期间，最初的摩擦很高，DLC膜表面磨损。在大气条件下，近乎无摩擦的类金刚石薄膜失去了超润滑性，容易磨损。这项研究是基于一种假设，即DLC表面是高度活性的，可以在环境空气中被氧化。本研究将通过一系列的控制实验，采用创新的实验设计，确定不同环境下DLC表面氧化层的厚度和成分，寻找能保证DLC在环境空气中实现超低摩擦、无磨损运行的蒸汽添加剂。本研究的新假设和实验结果不仅对DLC摩擦化学，而且对节能技术都将产生重大影响。这项工作将改变DLC表面是惰性的这一普遍观点。DLC表面是反应性的，特别是在氧气和潮湿的环境中。对DLC表面化学的深入了解将最终有助于开发涂层技术，通过减少寄生摩擦耗散和材料损失来实现节能。本科生将被要求分析在我们周围和工业场所的日常活动中损失了多少能量。参与该项目的研究生将接受多学科技能培训--化学工程、分子光谱学、摩擦学和涂料。这项研究的光谱数据和发现将被纳入研究生级别的描述。研究机会将提供给代表性不足的群体。

The research objective of this award is to understand and control the surface properties of diamond-like carbon (DLC) which is a technically important material. Various types of DLC are used to control friction and wear in a wide range of engineering applications due to their superior mechanical and tribological properties. The recent discovery of near-frictionless properties of hydrogenated DLC films can lead to innovations to reduce frictional energy loss and increase the service life of mechanical systems. However, the near-frictionless behavior is observed only in vacuum or extremely dry conditions after an initial induction period during which the friction is initially high and the DLC film surface wears. In atmospheric conditions, near-frictionless DLC films lose their superlubricity and are subject to wear. This research is based on a hypothesis that the DLC surface is highly reactive and can be oxidized in ambient air. Through a series of control experiments and using innovative experimental designs, this research will determine the thickness and composition of the oxidized surface layer in various environments and find vapor additives that can ensure ultra-low friction and wear-free operation of DLC in ambient air conditions.The new hypothesis and experimental findings of this research will have great impacts on not only DLC tribochemistry but also energy-saving technology. This work will change the common view that the DLC surface is inert. The DLC surface is reactive especially in oxygen and humid environments. The deeper understanding of the DLC surface chemistry will eventually help to develop coating technologies for energy conservation through reduction of parasitic frictional dissipation and material loss. Undergraduate students will be involved to analyze how much energy is lost in daily activities around us as well as in industrial places. Graduate students involved in this project will be trained with multidisciplinary skills - chemical engineering, molecular spectroscopy, tribology, and coatings. The spectral data and findings of this research will be incorporated into a graduate-level characterization. The research opportunity will be offered to underrepresented groups.