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Study of the fatigue wear behaviors of a tungsten carbide diamond-like carbon coating on 316L stainless steel J. Vac. Sci. Technol. A 30, 051506 (2012); 10.1116/1.4737619 Performance of diamond-like carbon-protected rubber under cyclic friction. I. Influence of substrate viscoelasticity on the depth evolutionWe perform large-scale molecular dynamics simulations on diamond-like carbon to study wear mechanism and law at the nanoscale. Our simulations show that material loss during sliding varies linearly with normal load and sliding distance, consistent with Archard's law. Our simulations also show that the number of chemical bonds across the contact interface during sliding correlates well with friction force, but not with material loss, indicating that friction and wear follow different mechanisms. Our analysis reveals the following wear mechanism: the shear traction causes mass accumulation at the trailing end of contact, which is then lost by a cluster detachment process. V C 2013 AIP Publishing LLC. [http://dx.

We investigated the edge atomic structures and elastic properties of defect-free phosphorene nanoribbons (PNRs). Density functional tight binding simulations were used to optimize two main edge configurations: armchair (AC) and zigzag (ZZ). It was found that the energy relaxation of PNRs leads to the noticeable changes in edge atomic configurations. The effective width of the edge region, which includes all the atoms involved in the edge relaxation, was found to contain approximately three atomic rows near the edge for both AC and ZZ PNRs. We further extracted the edge stress and modulus for the ZZ and AC edges. Both the AC and ZZ edge stresses of PNRs are positive, indicating tensile stress at the edges. In addition, both the AC and ZZ edge moduli are positive. However, the edge elastic modulus and edge stress of ZZ PNRs are about three times larger than those of AC PNRs. Furthermore, we showed that the tensile edge stresses along ZZ and AC edges are able to cause distortion in freestanding phosphorene nanoribbons. Our results highlight the importance of accounting for edge stresses in the design and fabrication of PNRs.