Molecular Dynamics Simulation Of Tribological Properties Of Self-Assembled Monolayers

In this paper, molecular dynamics simulation is conducted to simulate the interaction between self-assembled monolayers and silicon nitride, and the influence of temperature and pressure on it by using Materials Studio5.0. By analyzing interface binding energy, the tribological properties of self-assembled monolayers are studied. Multi-friction and wear tester is used to measure the friction coefficient of two kinds of self-assembled monolayers. The effects of load and sliding speed on friction coefficient are expounded. The main conclusion by comparing simulation results with experiments are obtained as below:1. Interface binding energy between MPS SAMs and Si3N4(001) ball is larger than that between APS and Si3N4(00) under normal temperature and pressure. The tribological properties of APS is better than that of MPS, which accords with experiments.2. Temperature and pressure affect the interface binding energy among MPS, APS and Si3N4(001). The friction coefficient of MPS decreases with the increasing temperature, however, the friction coefficient of APS increases with the increasing temperature. Friction coefficient of both self-assembled monolayers firstly increase with the increasing pressure and then decrease. The change of friction coefficient for MPS is larger.3. The affect of temperature and pressure on interface binding energy is mainly due to the interface van der Waals interaction and electrostatic interaction. However, the electrostatic interaction is smaller than van der Waals interaction, the interface van der Waals interaction plays a dominant role.4. The friction coefficient of both MPS and APS SAMs increases with the increasing load and sliding speed.