Theoretical Studies of the Microscopic Mechanisms of Friction Lubrication

材料界面的摩擦学过程具有重要的技术意义，因为它们是磨损、退化和摩擦能量耗散的来源。对摩擦学现象的物理和化学的基本了解对于开发在极端环境条件下和长时间工作所需的先进材料特别重要。虽然有大量的经验数据，但没有详细的摩擦学现象的微观理论。该项目涉及材料界面摩擦、润滑和磨损的微观机制。它集中在两个主题上。它们是对润滑剂、润滑和塑性流动的研究，以及对非晶态和晶态材料之间的摩擦学过程的研究。这些研究将通过分子动力学(MD)模拟进行。MD方法可以通过积分经典运动方程来跟踪相互作用粒子系统动力学状态的时间演化。在这种方法中，粒子间的相互作用由对位势来描述。这种类型的分析中通常包括的粒子数量在1到10,000之间。该方法适用于处于不同聚集阶段(固体、液体、结晶或非晶态)的体系，在各种条件下，以及存在复杂的相互作用和外场时。此外，该方法还可以研究材料在压力和温度升高时的结构变化，有证据表明，仔细的模拟与实验结构数据是一致的。该项目的目的是提供一种系统的方法来预测摩擦、润滑和磨损过程的复杂现象。

Tribological processes at materials interfaces are of major technological importance since they are the source of wear and degradation as well as frictional energy dissipation. Fundamental understanding of the physics and chemistry of tribological phenomena is of particular importance for the development of advanced materials required to function under extreme ambient conditions and for long periods of time. Although there is an immense body of empirical data, there is no detailed microscopic theory of tribological phenomena. This project is concerned with the microscopic mechanisms of friction, lubrication and wear at material interfaces. It focuses on two topics. They are studies of lubricants, lubrication, and plastic flow,and studies of tribological processes at interfaces between amorphous and crystalline materials. These studies will be performed through molecular dynamics (MD) simulations. The MD method allows one to follow the time evolution of the dynamical state of a system of interacting particles by integration of the classical equations of motion. In this method, the particle interactions are prescribed by pair potentials. The number of particles normally included in this type of analysis is between one and ten thousand. The method is applicable to systems in various stages of aggregation (solid, liquid, crystalline, or amorphous), under various conditions and in the presence of complex interactions and external fields. Furthermore, the method allows the study of structural changes that materials undergo at elevated pressure and temperature and there is evidence that careful simulations are in agreement with experimental structural data. The intent of the project is to provide a systematic method of predicting the complex phenomena of friction, lubrication and wear processes.