On-demand Generation of Diamond-like-carbon Layers for Efficient Lubrication of Mechanical Systems

运输占美国石油消费的70%。改善运输和其他机械系统的润滑可提高效率、减少维护并降低与机油消耗相关的成本。同样重要的是，汽车发动机等机械系统在启动和停止时很容易磨损。这一点对于混合动力汽车尤其重要，因为每当传动系统切换到电池作为动力源时，它们的发动机就会启动和停止，对于许多正在实施这种“启动-停止”技术的新传统乘用车来说，这种技术通过在车辆在交通或红绿灯时空转时自动关闭发动机来降低燃油消耗。需要为这些具有频繁启停循环的现代发动机系统设计新的润滑剂。研究小组探索了在常规发动机油中引入新的润滑油添加剂，当在启停循环中经历的条件下，这些添加剂很容易分解为具有润滑性和保护性的类金刚石碳层。因此，这些涂层可在需要时随时随地提供减摩和磨损保护。这一多学科的研究涉及表面化学、材料科学和机械工程；它不仅在学科领域提供广泛的研究生培训，而且还在通信、创业、国际和多文化接触以及积极参与专业活动方面提供培训。本研究的目的是探索和开发一种新的方法，在摩擦部件表面原位和按需沉积润滑类金刚石薄膜。该方法使用表面活性分子(溶解在基础油中)，通过应变的亚稳态碳环进行功能化。这些分子的表面活性基团使它们很容易吸附在摩擦成分的表面上。在边界条件下，粗糙处摩擦加热产生的热能导致这些分子的亚稳碳环分解，形成有色的类金刚石碳层，从而提供就地和按需的减摩和磨损保护。研究小组计划从两个方面对这些添加剂分子的化学结构进行系统的修饰：表面活性基团的化学性质以及表面活性基团和应变亚稳态碳环之间的-CH2间隔基的数量。研究将探索这些添加剂分子的化学结构、分解动力学和在不同边界润滑条件下的摩擦学性能之间的关系。

Transportation accounts for 70 percent of the oil consumption in the US. Improving lubrication in transportation and other mechanical systems results in better efficiency, reduced maintenance and cost associated with oil consumption. Just as critical, mechanical systems such as automotive engines are prone to wear during starts and stops. This is particularly important for hybrid vehicles, whose engines start and stop each time the drivetrain switches from and to the battery as the power source, and for many new conventional passenger cars that are implementing such "start-stop" technology to reduce fuel consumption by automatically shutting the engine off when the vehicle is idling in traffic or at stoplights. There is a need for new lubricants designed for these modern engine systems with frequent start-stop cycles. The research team explores the introduction of new lubricant additives into regular engine oils that readily decompose into lubricious and protective diamond-like-carbon layers when subjected to conditions experienced in start-stop cycles. These layers therefore provide friction reduction and wear protection when and where they are needed. This multidisciplinary research involves surface chemistry, materials science, and mechanical engineering; it provides broad-based graduate training not only in subject areas, but also in communications, entrepreneurship, international and multi-cultural exposure, and active participation in professional activities. The objective of this research is to explore and develop a novel approach to in situ and on-demand deposition of lubricious diamond-like-carbon films onto tribo-component surfaces. The approach uses surface-active molecules (dissolved in base oil) that are functionalized with strained metastable carbon rings. The surface-active group of these molecules allows them to readily absorb onto tribo-component surfaces. Under boundary conditions, thermal energy due to frictional heating at asperities causes the metastable carbon rings of these molecules to decompose, resulting in the formation of a lubricious diamond-like-carbon layer, thus providing in situ and on-demand friction reduction and wear protection. The research team plans to systematically modify the chemical structure of these additive molecules in two aspects: the chemical nature of the surface-active group and the number of -CH2 spacers between the surface-active group and the strained metastable carbon ring. Research investigations will explore the relationship among the chemical structure of these additive molecules, decomposition kinetics, and the tribological performance under different boundary lubrication conditions.