Friction reduction and wear mechanisms of Si-DLC film in humid environment: A ReaxFF MD study

Abstract

This work revealed the friction reduction and wear mechanism of Si-DLC film in humid environment under varying loads and temperatures, utilizing reactive force field molecular dynamics (ReaxFF MD). The results show that Si-OH groups generated by the tribochemical reaction can promote water-lubricated film formed, which significantly reducing the friction force of the tribosystem. Under low loads, Si-DLC film undergo chemical oxidation wear, where the bonds between Si atoms tend to fracture first, while the C and Si atoms are bridged first by O atoms through oxidation and ultimately bridge bonds fractured to realize wear. Increasing load, the chemical wear is transformed into mechanical wear with high wear. Additionally, high temperature reduces the friction force of the tribosystem by increasing the low-shear strength structure of Si-DLC film, but this causes high wear of Si-DLC film.