Papers by Keyword: Nanomachining

Abstract: The study of nanoscale machining phenomena and processes are effectively been carried out by using the molecular dynamics (MD) simulation. The MD provides explanation of material behaviour that are difficult to observe or even impossible through experiments. To carry out reliable simulations, the method depends on critical issues, which include the choice of appropriate interatomic potentials and the integration time step. The selection of the timestep in the MD simulation of nanomachining is the major focus of this investigation. A too low timestep would be computationally expensive and also a too high timestep would cause chaotic behaviour in the simulation. Computational experiments were conducted to check for the range of timestep that is appropriate for the simulation of nanomachining of copper. It was observed from the total energy variations, that time step in the range of 0.1 to 0.4 fs could be used to procure stable simulations in copper, for the configuation employed.

Abstract: The atomic surface finish or roughness can be defined as the roughness limit of a surface. Its value has been demonstrated both in theory and in experiments to be non-zero [1, 2]. This parameter is very important in assessing the quality of high performance nanosurfaces, and so its understanding is very crucial. In this study, multi-pass nanometric atomistic simulations were carried out, with a diamond tool on a copper workpiece to create a nanosurface and the results provide the platform from which the atomic surface roughness was evaluated. The estimated surface roughness (Sa) was in the order of 0.3nm.

Abstract: There is a need to choose appropriate interatomic empirical potentials for the molecular dynamics (MD) simulation of nanomachining, so as to represent chip formation and other cutting processes reliably. Popularly applied potentials namely; Lennard-Jones (LJ), Morse, Embedded Atom Method (EAM) and Tersoff were employed in the molecular dynamics simulation of nanometric machining of copper workpiece with diamond tool. The EAM potentials were used for the modelling of the copper-copper atom interactions. The pairs of EAM-Morse and EAM-LJ were used for the workpiece-tool (copper-diamond) atomic interface. The Tersoff potential was used for the carbon-carbon interactions in the diamond tool. Multi-pass simulations were carried out and it was observed that the EAM-LJ and the EAM-Morse pair potentials with the tool modelled as deformable with Tersoff potential were best suitable for the simulation. The former exhibit the lowest cutting forces and the latter has the lowest potential energy.

Abstract: The current status of nanofabrication briefly reviewed, then molecular dynamics model of poly-silicon is founded on micro-nanoscale with molecular dynamics method, in which several typical defects are distributed reasonably. Molecular dynamics simulation of nanocutting process is conducted according to the simulation model. Keeping the other conditions remain unchanged, simulating calculation is made by reasonably changing cutting parameters such as cutting velocity and cutting depth, through which the changes of the morphology structure of workpiece surface,cutting force and system potential energy are observed. The simulation results are compared and studied, then the influence laws of each parameter on morphology structure of workpiece surface, cutting force and system potential energy are analyzed. Based on this, the mechanism of poly-silicon nanomachining is discussed .

Abstract: This study focused on the ultrasonic nanomachining by atomic force microscopy (AFM) to understand the phenomena of the ultrasonic nanomachining. The workpiece is an Au/Ti thin film and coated on the quartz crystal resonator (QCR). The ultrasound vibration of workpiece is carried out by used the Quartz crystal microbalance (QCM). And a normal force measurement model was built by force curve measurements in ultrasound vibration environment. The influence of different experimental parameters can be studied such as normal force and repeat number on the cutting depth and chip stacking. After the experiments, it can be found that the ultrasonic nanomachining by AFM is possessed great influence on the cutting depth.

Abstract: In this paper, the nanomachining experiments on the SPR3001 photoresistor thin films were processing by contact mode atomic force microscopy (AFM). After the experiment, it can be found, in the nanomachining, the greater the indented distance along the Z-axis depth, carved out of the groove depth and groove width of nanoline is greater. The influences of cutting directions on line width and cutting depth during nanomachining were quite a few and the cutting situation was stable by lateral nanomachining. This article also successfully processed the regular hexagonal nanopattern, also proves the nanomachining ability of the AFM probe is good at nanoscale patterned on photoresistor thin films.

Abstract: This study focused on the combination of atomic force microscopy (AFM) and quartz crystal microbalance (QCM) to construct the ultrasound assisted AFM base nanomachining experimental platform, and to construct the experimental planning of ultrasonic assisted nanomachining, to understand the phenomena of the ultrasound assisted AFM base nanomachining. Firstly, we combined the AFM and QCM to construct the ultrasound assisted AFM base nanomachining experimental platform. And a normal force measurement model was built by force curve measurements in ultrasound vibration environment. Next, the ultrasonic assisted nanomachining was carried out and aimed at brittle and ductile materials to probe into the influence of different experimental parameters such as probe speed, normal force and workpiece material on the cutting depth, width and chip stacking. After the experiments, it is succeeded in the ultrasound assisted AFM base nanomachining experimental platform in this study. And it can be found that the ultrasonic assisted nanomachining is possessed great influence on the cutting depth and width.

Abstract: Fabrication of micro and nanoscale components are in high demand for various applications in diversified fields that include automotive, electronics, communication and medicine. Focused ion beam (FIB) machining is one of the techniques for microfabrication of micro devices. This paper presents a review of FIB machining technology that include its parameter, responses, its important component systems, as well as the fundamentals of imaging, milling (etching) and deposition techniques. The application of FIB in micromachining is also presented.

Abstract: To study the effect of different sample materials on the nano dynamic ploughing process in the AFM tapping mode, the spring-oscillator model is employed to simulate the vibrating AFM tip to deform the sample surface. On the surface of different samples with the Young’s modulus of 0.2 GPa, 80 GPa and 180 Gpa, the interaction between the tip and the sample is simulated with different driven amplitudes, spring constants, tip radius and original tip-sample distances. These effects are studied. Results show that the sample with a smaller Young’s modulus is suitable for being used as the sample machined by the dynamic ploughing technique. When the Young’s modulus is greater than 80 GPa, the machine depth is so small that the machining process can not be controlled as we required.

Abstract: The objective of this paper is to understand the abrasive wear mechanism for producing a nano scale groove on a bulk material through nano machining. A nano indenter equipped with a nano scratching attachment was used for nano machining operation and in situ observation of the machined surfaces. Two different tools (Berkovich and Conical) with the same tip radius (100nm) but different edge geometries were used to machine both Copper and Nickel coatings. It was found that the percentage of elastic recovery was lower for Cu than Ni during this nano machining operations. Hence, the deformation mechanism in nano machining operation was identified as elasto-plastic in nature as opposed to the well established completely plastic mode of conventional machining operations. The pile up volume due to plastic deformation was utilized to distinguish between the ploughing and cutting modes of abrasive wear mechanisms. The results reveal that the ploughing mechanism was dominant for Cu and the cutting mechanism was dominant for Ni machining. Moreover, both mechanisms ploughing and cutting were the dominant modes of abrasive wear using the Berkovich tip compared to the Conical tip for producing a nano scale groove through nano machining.