The hardness of amorphous Si-DLC films by molecular dynamics simulations

Abstract

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 structure and mechanical properties have changed greatly with the increasing silicon content. Therefore, molecular dynamics (MD) simulations were used to generate hydrogen-free Si-DLC films and study their nano-indentation process under the interaction of a diamond indenter. The results show that sp3/sp2(C) (only carbon atoms) always decreases with the increasing silicon content. But sp3/sp2(C+Si) ratio increases firstly and reaches a maximum at the silicon content of 0.2, and then decreases with the further increase of the silicon content. Bulk modulus and hardness of the Si-DLC films both decrease with the increasing of the silicon content, which has the same trend with Papakonstantinou and Ikeyama’s results. It is concluded that the hardness of the Si-DLC films is dependent on sp3/sp2(C), not sp3/sp2(C+Si).