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)