Molecular Dynamics Simulation Of Mechanical Behavior Of Nanofilm

As the development of MEMS/NEMS technology, the gradually incensementof the integration of the system, the enhancement of the function, the diminution ofprocess size, these are put forward higher requirements for the performance of thematerial. Traditional MEMS/NEMS technology is dominated by silicon materials,However, because of the limit the inherent properties of silicon, people need to findsome new material instead of silicon to be used in MEMS/NEMS devices. Overall,the metal material (such as copper) and the DLC is considered to be one of themore promising materials because of their excellent properties.Subject to the limitations of space dimensions, materials always exist in theform of nano-film in MEMS/NEMS devices. Due to the strong size effect,nanoscale materials will show different material properties comparing with themacroscale. This paper is going to discuss the mechanics of single crystal copperfilm and the amorphous carbon film by molecular dynamics simulation of nano-indentation and nano-scratch.To analyze the mechanical properties of single copper film, we will build anMD model of the rigid diamond spherical indenter and single crystal coppersubstrate to simulate the nanoindentation process. Through the relationship of thenormal force and the indentation depth in the simulation process, we can analyzethe contact behavior of nanoscale, and the simulation results is compared with theclassic Hertz elastic contact theory. At the same time, we can study the elastic andplastic deformation through the force displacement curve of loading and unloadingprocess during the nanoindentation process. In addition, this article will examinethe influence of the loading speed and the radii of the spherical indenter to themechanical properties of the substrate.In order to study the mechanical properties of amorphous carbon, firstly,through the rapid quenching method, this article will use three different potentialfunctions, to generate different density of the amorphous carbon structure from2.2g/cm3to3.2g/cm3, and analyze the difference of the micro structure of theobtained amorphous carbon and compare the ability of different potentials todescribe the interaction between the two atoms in the amorphous carbon throughcoordination number and radial distribution function,. Secondly, we will establishthe molecular dynamics simulation model of rigid diamond spherical indenter andthe amorphous carbon during the nano-indentation and nano-scratching processaccording to the structure of amorphous carbon obtained by the formal simulation, and study the mechanical properties of amorphous carbon of different densities anddifferent structure according to the load-displacement curve during the nano-indentation process. The results show that high-density amorphous carbon has astronger ability of resisting deformation; under the same density, the amorphouscarbon with high sp3content has better mechanical properties. Through the analysisof the process of the nano-scratch, we found that the tribo-chemical reactionsbetween the indenter and the substrate happen during the friction process, and thefriction increases linearly with the increasement of the normal load; the high-density amorphous carbon has excellent friction performance relative to the low-density amorphous carbon under the same load.