Amorphization anisotropy and the internal of amorphous layer in diamond nanoscale friction

N Yang and WJ Zong and ZQ Li and T Sun, COMPUTATIONAL MATERIALS SCIENCE, 95, 551-556 (2014).

DOI: 10.1016/j.commatsci.2014.08.040

In this work, molecular dynamic (MD) simulation is employed to investigate the formation and evolution of amorphous carbons in the surface layer of diamond crystal as the frictional sliding is performed on diamond (100) plane. Simulation results reveal that the formation of amorphous carbons at the sliding interface is inevitable due to the friction. In this case, transformation from diamond sp(3) hybridized carbons to sp(2) hybridization structures is dominant. More interestingly, most of the sp hybridized carbons appear on the topmost surface of the amorphous layer. Amorphization rate in sliding along the 100 direction is greater than that along the 110 direction due to the smaller resistance forces. In the light of the velocity variation of carbon atoms, the amorphous layer is divided into two layers, i.e. the coherent layer and transition layer. Moreover, a density transition region appears with the formation of amorphous carbons, and the thickness of transition region can be used to characterize the amorphization degree. (C) 2014 Elsevier B.V. All rights reserved.

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