Rolling Resistance and Mechanical Properties of Grinded Copper Surfaces Using Molecular Dynamics Simulation

Nanoscale Research Letters, Sep 2016

Mechanical properties of copper (Cu) film under grinding process were accomplished by molecular dynamics simulation. A numerical calculation was carried out to understand the distributions of atomic and slip vector inside the Cu films. In this study, the roller rotation velocity, temperature, and roller rotation direction change are investigated to clarify their effect on the deformation mechanism. The simulation results showed that the destruction of materials was increased proportionally to the roller rotation velocity. The machining process at higher temperature results in larger kinetic energy of atoms than lower temperature during the grinding process of the Cu films. The result also shows that the roller rotation in the counterclockwise direction had the better stability than the roller rotation in the clockwise direction due to significantly increased backfill atoms in the groove of the Cu film surface. Additionally, the effects of the rolling resistances on the Cu film surfaces during the grinding process are studied by the molecular dynamics simulation method.

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Rolling Resistance and Mechanical Properties of Grinded Copper Surfaces Using Molecular Dynamics Simulation

Liang et al. Nanoscale Research Letters Rolling Resistance and Mechanical Properties of Grinded Copper Surfaces Using Molecular Dynamics Simulation Shih-Wei Liang 0 Chih-Hao Wang 0 Te-Hua Fang 0 0 Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences , Kaohsiung 80778 , Taiwan Mechanical properties of copper (Cu) film under grinding process were accomplished by molecular dynamics simulation. A numerical calculation was carried out to understand the distributions of atomic and slip vector inside the Cu films. In this study, the roller rotation velocity, temperature, and roller rotation direction change are investigated to clarify their effect on the deformation mechanism. The simulation results showed that the destruction of materials was increased proportionally to the roller rotation velocity. The machining process at higher temperature results in larger kinetic energy of atoms than lower temperature during the grinding process of the Cu films. The result also shows that the roller rotation in the counterclockwise direction had the better stability than the roller rotation in the clockwise direction due to significantly increased backfill atoms in the groove of the Cu film surface. Additionally, the effects of the rolling resistances on the Cu film surfaces during the grinding process are studied by the molecular dynamics simulation method. Grinding; Molecular dynamics; Rotation velocity; Rolling resistance Background The tribological and grinding characteristics of films on the nanoscale have become increasingly important due to increasing numbers of applications such as nanoimprint technology [ 1 ] and roller-type nanoimprint lithography (RNIL) [ 2 ]. Li et al. [ 3 ] used surface mechanical grinding treatment (SMGT) at cryogenic temperatures to synthesize a gradient nano-micro-structure in the surface layer of bulk metals. Fang et al. [ 4 ] used a SMGT for preparing a nanograined copper film with a spatial gradient in grain size and showed a different governing deformation mechanism. Li et al. [ 5 ] reported that the mechanisms of subsurface damage and material removal of monocrystalline copper in nanoscale high-speed grinding and result showed that a large tip radius or depth of cut would get a greater temperature rise in the workpiece and lower grinding velocity made more intrinsic stacking faults. However, they more accurately evaluated the properties of the material by applying molecular dynamics (MD) simulations to the rolling–machining process, thereby incorporating more preliminary information for the tooling design and determining the optimum processing conditions. Wu et al. [ 6 ] studied the effect of the roller tooth’s taper angle, imprint depth, and imprint temperature on the properties of single-crystalline gold and observed that imprint force and adhesion increase with increasing imprint depth and decreasing taper angle. Lin et al. [ 7 ] used a MD simulation with the embedded atom method (EAM) to study the deformation process of pure copper nanorods in the nanoforming process; they reported that the pure copper nanorods undergo plastic deformation because of structural defects owing to higher energies in the material, wherein the higher energies are induced by large compressive loadings and high temperatures. Furthermore, the rolling process is similar to the milling, polishing, grinding, and cutting processes performed with a machining center. On the basis of MD simulations, Yang et al. [ 8 ] proposed a single-crystalline copper structure for ultra-precision polishing with the selfrotation of a diamond abrasive. They observed that an increase in abrasive rotation velocity decreased the tangential force, resulting in diminished material machine quality. In a previous study [ 9 ], various rolling–sliding processes associated with a diamond in a Cu system were simulated by the MD method. The numerical results showed the maximum normal and frictional forces of Cu at a rotation velocity of zero in the rolling–sliding process because of the very high sliding resistance at the interface between the diamond and Cu. Unfortunately, the authors did not report the details of the rolling resistance for the Cu material surface. Thus, many challenges remain, such as understanding the rolling resistance, to fully elucidate the grinding mechanism of a roller on a Cu surface. As evident from the above discussion, an MDsimulation-based, atomic-scale investigation of the mechanical properties and deformation mechanism of Cu films used in the grinding process with various roller rotation velocities is warranted. In the present study, we focus on the effects of the roller rotation velocity, temperature, direction, and rolling resistance on the grinding process of Cu films using MD simulations. The results are discussed in terms of the slip vector, deformation mechanism, and rolling resistance. Methodology In our MD simulations, a three-dimensional ph (...truncated)


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Shih-Wei Liang, Chih-Hao Wang, Te-Hua Fang. Rolling Resistance and Mechanical Properties of Grinded Copper Surfaces Using Molecular Dynamics Simulation, Nanoscale Research Letters, 2016, pp. 401, Volume 11, Issue 1, DOI: 10.1186/s11671-016-1616-1