Soft abrasive facilitating materials removal of SiO2/Si bilayer materials: A molecular dynamics study

Abstract

In this work, three different tips are considered to study the influences on the friction and wear behaviors of monocrystalline silicon covered with an amorphous SiO2 film using molecular dynamics simulation. The results show that the friction force for the SiO2 tips, especially for the non-rigid tip is much higher than that of the diamond tip because of the adhesion effect between the SiO2 tips and SiO2/Si bilayer sample. The film beneath the diamond tip undergoes densification and phase transformation occurs to silicon substrate during sliding. However, materials removal takes place in SiO2/Si samples against the non-rigid SiO2 tip because of compressed and sheared soft tip during sliding, causing enhanced true contact area and generation of more Si–O bridge bonds between the sliding interfaces. Meanwhile, the resultant contact area results in declined contact stress and a damage-free silicon substrate. It is found that the indentation-plowing model of material removal is no longer valid during sliding against the diamond tip, and that the indentation-adhesion mechanism contributes to the materials removal of sample slid by a soft SiO2 tip and results in a damage-free surface under the normal force of 40 nN.