Molecular dynamics simulations of atomic-scale tribology between amorphous DLC and Si-DLC films

Silicon-doped diamond-like carbon (Si-DLC) films possess the potential to improve wear performance of DLC films in humid atmospheres and at higher temperatures. But many experimental results of Si-DLC films show that their structures and tribological properties changed greatly with silicon content. Therefore, molecular dynamics (MD) simulations were used to study the sliding friction process between DLC and Si-DLC films on un-lubricated boundary condition. The results show that a part of sp2 bonding of the Si-DLC films is converted into sp3 bonding with the addition of silicon atoms, and the sp3/sp2 ratio increases with the increase in silicon content. A transfer film between the DLC and Si-DLC films is formed and the friction force changes with the silicon content. Moreover, the simulations have showed that the silicon addition promotes the bonding of interfilms being formed.

Research highlights
► Molecular dynamics simulations with Tersoff potential were used to study the sliding friction process between DLC and Si-DLC films on un-lubricated boundary condition.
► The results show that a part of sp2 bonding of the Si-DLC films is converted into sp3 bonding with the addition of silicon atoms, therefore the sp3/sp2 ratio increases with the increase in silicon content.
► A transfer film between the DLC and Si-DLC films is formed and the friction force changes with the silicon content.
► Moreover, the simulations have showed that the silicon addition promotes the bonding being formed of interfilms.