A Study on the Dynamic Forming Mechanism Development of the Negative Poisson's Ratio Elastomer Molds-Plate to Plate (P2P) Forming Process.

This study proposed a dynamic forming mechanism development of the negative Poisson's ratio elastomer molds-plate to plate (P2P) forming process. To dynamically stretch molds and control the microstructural shape, the proposal is committed to using the NPR structure as a regulatory mechanism. The NPR structural and dynamic parallel NPR-molds to control microstructure mold-cores were simulated and analyzed. ANSYS and MATLAB were used to simulate and predict dynamic NPR embossing replication. The hot-embossing and UV-curing dynamic NPR P2P-forming systems are designed and developed for verification. The results illustrated that the dynamic forming mechanism of the negative Poisson's ratio elastomer molds proposed by this study can effectively control microstructure molds. This can effectively predict and calculate the geometrical characteristics of the microstructures after embossing. The multi-directional dynamic NPR microstructural replication process can accurately transfer microstructures and provide high transfer rate-replication characteristics.

Prediction Surface Morphology of Nanostructure Fabricated by Nano-Oxidation Technology.

Atomic force microscopy (AFM) was used for visualization of a nano-oxidation technique performed on diamond-like carbon (DLC) thin film. Experiments of the nano-oxidation technique of the DLC thin film include those on nano-oxidation points and nano-oxidation lines. The feature sizes of the DLC thin film, including surface morphology, depth, and width, were explored after application of a nano-oxidation technique to the DLC thin film under different process parameters. A databank for process parameters and feature sizes of thin films was then established, and multiple regression analysis (MRA) and a back-propagation neural network (BPN) were used to carry out the algorithm. The algorithmic results are compared with the feature sizes acquired from experiments, thus obtaining a prediction model of the nano-oxidation technique of the DLC thin film. The comparative results show that the prediction accuracy of BPN is superior to that of MRA. When the BPN algorithm is used to predict nano-point machining, the mean absolute percentage errors (MAPE) of depth, left side, and right side are 8.02%, 9.68%, and 7.34%, respectively. When nano-line machining is being predicted, the MAPEs of depth, left side, and right side are 4.96%, 8.09%, and 6.77%, respectively. The obtained data can also be used to predict cross-sectional morphology in the DLC thin film treated with a nano-oxidation process.

The study on the nanomachining property and cutting model of single-crystal sapphire by atomic force microscopy.

This study focused on the nanomachining property and cutting model of single-crystal sapphire during nanomachining. The coated diamond probe is used to as a tool, and the atomic force microscopy (AFM) is as an experimental platform for nanomachining. To understand the effect of normal force on single-crystal sapphire machining, this study tested nano-line machining and nano-rectangular pattern machining at different normal force. In nano-line machining test, the experimental results showed that the normal force increased, the groove depth from nano-line machining also increased. And the trend is logarithmic type. In nano-rectangular pattern machining test, it is found when the normal force increases, the groove depth also increased, but rather the accumulation of small chips. This paper combined the blew by air blower, the cleaning by ultrasonic cleaning machine and using contact mode probe to scan the surface topology after nanomaching, and proposed the "criterion of nanomachining cutting model," in order to determine the cutting model of single-crystal sapphire in the nanomachining is ductile regime cutting model or brittle regime cutting model. After analysis, the single-crystal sapphire substrate is processed in small normal force during nano-linear machining; its cutting modes are ductile regime cutting model. In the nano-rectangular pattern machining, due to the impact of machined zones overlap, the cutting mode is converted into a brittle regime cutting model.

Evaluation of tribological behavior of Al-Co-Cr-Fe-Ni high entropy alloy using molecular dynamics simulation.

High-entropy alloys have been studied extensively for their excellent properties and performance, including outstanding strength and resistance to oxidation at high temperatures. This study employed molecular dynamics simulation to produce a high-entropy alloy containing an equal molar ratio of Al, Co, Cr, Fe, and Ni and investigated the tribological behavior of the material using a diamond tool in a vacuum environment. We also simulated a AlCoCrFeNi high-entropy alloy cooled from a high temperature molten state to 300 K in a high-speed quenching process to produce an amorphous microstructure. In a simulation of nanoscratching, the cutting force-distance curve of high-entropy alloys was used to evaluate work hardening and stick-slip. An increase in temperature was shown to reduce the scratching force and scratching resistance. Nanoscratching the high-entropy alloy at elevated temperatures provided evidence of work hardening; however, the degree of work hardening decreased with an increase in temperature. And it can also be found that when the temperature is higher, the fluctuation of the cutting force curve is greater.

The study of nanoscratch and nanomachining on hard multilayer thin films using atomic force microscope.

In this study, nanoscratching and nanomachining were conducted using an atomic force microscope (AFM) equipped with a doped diamond-coated probe (DDESP-10; VEECO) to evaluate the fabrication of nanopatterns on hard, Cr2N/Cu multilayer thin films. The influence of normal force, scratch speed, and repeated scratches on the properties of hard multilayer thin films was also investigated. The nanoscratch experiments led researchers to establish a probe preparation and selection criteria (PPS criteria) to enhance the stability and accuracy of machining hard materials. Experimental results indicate that the depth of grooves produced by nanoscratching increased with an increase in normal force, while an increase in the number of scratches in a single location increased the groove depth but decreased friction. Therelationships among normal force and groove depth more closely resembled a logarithmic form than other mathematical models, as did the relationship between repeated scratching and its effect on groove depth and friction. The influence of scratch speed on friction was divided into two ranges. Between 0.1 and 2 µm/s, friction decreased logarithmically with an increase in scratch speed; however, when the speed exceeded 2 µm/s, the friction appeared stable. In this study, multilayered coatings were successfully machined, demonstrating considerable promise for the fabrication of nanopatterns in multilayered coatings at the nanoscale.

Fabricating nanostructures through a combination of nano-oxidation and wet etching on silicon wafers with different surface conditions.

This study investigates the surface conditions of silicon wafers with native oxide layers (NOL) or hydrogen passivated layers (HPL) and how they influence the processes of nano-oxidation and wet etching. We also explore the combination of nano-oxidation and wet etching processes to produce nanostructures. Experimental results reveal that the surface conditions of silicon wafers have a considerable impact on the results of nano-oxidation when combined with wet etching. The height and width of oxides on NOL samples exceeded the dimensions of oxides on HPL samples, and this difference became increasingly evident with an increase in applied bias voltage. The height of oxidized nanolines on the HPL sample increased after wet etching; however, the width of the lines increased only marginally. After wet etching, the height and width of oxides on the NOL were more than two times greater than those on the HPL. Increasing the applied bias voltage during nano-oxidation on NOL samples increased both the height and width of the oxides. After wet etching however, the increase in bias voltage appeared to have little effect on the height of oxidized nanolines, but the width of oxidized lines increased. This study also discovered that the use of higher applied bias voltages on NOL samples followed by wet etching results in nanostructures with a section profile closely resembling a curved surface. The use of this technique enabled researchers to create molds in the shape of a silicon nanolens array and an elegantly shaped nanoscale complex structures mold.

The fabrication and preservation of nanostructures on silicon wafers with a native oxide layer.

This study used nano-oxidation lithography to create oxidized circular nanostructures on a silicon wafer with a native oxide layer (NOL). We also investigated the impact of wet etching on the size of circular oxidized nanostructures and examined how the method and duration of preservation affect them. Experimental results show that the height and width of oxidized circular nanostructures increase proportionally with applied voltage. After wet etching, an increase in applied voltage resulted in a marked increase in the width of the circular nanostructures, a decrease in the inner diameter, and little variation in height. We further demonstrated that in a moist environment, the oxidation process continues, resulting in a further increase in height and width. During the initial stages of preservation, these changes occurred rapidly; however, the increase was negligible after 30 days. We propose the concept of reaction area (RA) ratio to explain the above phenomenon and provide evidence to support these claims. Our results led us to a simple and yet effective method of preserving oxidized circular nanostructures, called the electrostatic patch preservation (EPP) method, to overcome problems associated with changes in size occurring during the preservation of silicon nanostructure molds.

High-voltage nano-oxidation in deionized water and atmospheric environments by atomic force microscopy.

This study used atomic force microscopy (AFM), metallic probes with a nanoscale tip, and high-voltage generators to investigate the feasibility of high-voltage nano-oxidation processing in deionized water (DI water) and atmospheric environments. Researchers used a combination of wire-cutting and electrochemical etching to transform a 20-µm-thick stainless steel sheet into a conductive metallic AFM probe with a tip radius of 60 nm, capable of withstanding high voltages. The combination of AFM, high-voltage generators, and nanoscale metallic probes enabled nano-oxidation processing at 200 V in DI water environments, producing oxides up to 66.6 nm in height and 467.03 nm in width. Oxides produced through high-voltage nano-oxidation in atmospheric environments were 117.29 nm in height and 551.28 nm in width, considerably exceeding the dimensions of those produced in DI water. An increase in the applied bias voltage led to an apparent logarithmic increase in the height of the oxide dots in the range of 200-400 V. The performance of the proposed high-voltage nano-oxidation technique was relatively high with seamless integration between the AFM machine and the metallic probe fabricated in this study.

The study on the atomic force microscopy base nanoscale electrical discharge machining.

This study proposes an innovative atomic force microscopy (AFM) based nanoscale electrical discharge machining (AFM-based nanoEDM) system which combines an AFM with a self-produced metallic probe and a high-voltage generator to create an atmospheric environment AFM-based nanoEDM system and a deionized water (DI water) environment AFM-based nanoEDM system. This study combines wire-cut processing and electrochemical tip sharpening techniques on a 40-µm thick stainless steel sheet to produce a high conductive AFM probes, the production can withstand high voltage and large current. The tip radius of these probes is approximately 40 nm. A probe test was executed on the AFM using probes to obtain nanoscales morphology of Si wafer surface. The silicon wafer was as a specimen to carry out AFM-base nanoEDM process in atmospheric and DI water environments by AFM-based nanoEDM system. After experiments, the results show that the atmospheric and DI water environment AFM-based nanoEDM systems operate smoothly. From experimental results, it can be found that the electric discharge depth of the silicon wafer at atmospheric environments is a mere 14.54 nm. In a DI water environment, the depth of electric discharge of the silicon wafer can reach 25.4 nm. This indicates that the EDM ability of DI water environment AFM-based nanoEDM system is higher than that of atmospheric environment AFM-based nanoEDM system. After multiple nanoEDM process, the tips become blunt. After applying electrochemical tip sharpening techniques, the tip radius can return to approximately 40 nm. Therefore, AFM probes produced in this study can be reused.

Study on advanced nanoscale near-field photolithography.

At present, applying a near-field optical microscope to photolithographic line segment fabrication can only obtain nanoscale line segments of equal cutting depths, and cannot result in 3D shape fabrication. This study proposes an innovative line segment fabrication model of near-field photolithography that adjusts an optical fiber probe's field distance to control the exposure energy density, and moreover constructs an exposure energy density analysis method of the innovative photolithographic line segment fabrication. During the exposure simulation process of the innovative line segment fabrication model of near-field photolithography, the near-field distance between the optical fiber probe and the photoresist surface increases gradually, whereas the exposure energy density distribution decreases gradually. As a result, the cutting depth becomes shallower and the full-width at half maximum (FWHM) increases. The results of this study can serve as a theoretical reference for developing advanced nanoscale near-field photolithography techniques, to which an important and groundbreaking contribution is made.

Error analysis and regression mode of the V-grooved sample in the atomic force microscope simulation measurement mode by the molecular mechanics.

Based on the molecular mechanics, this study uses the two-body potential energy function to construct a trapezoidal cantilever nano-scale simulation measurement model of contact mode atomic force microscopy (AFM) under the constant force mode to simulate the measurement the nano-scale V-grooved standard sample. We investigate the error of offset distance of the cross-section profile when using the probes with different trapezoidal cantilever probe tip radii (9.5, 8.5, and 7.5 A) to scan the peak of the V-grooved standard sample being reduced to one-tenth (1/10) of its size, and use the offset error to inversely find out the regression equation. We analyze how the tip apex as well as the profile of the tip edge oblique angle and the oblique edge angle affects the offset distance. Furthermore, a probe with a larger radius of 9.5 nm is used to simulate and measure the offset error of scan curve, and acquire the regression equation. By the conversion proportion coefficient of size (omega), and revising the size-reduced regression equation during the small size scale, a revised regression equation of a larger size scale can be acquired. The error is then reduced, further enhancing the accuracy of the AFM scanning and measurement.

A study of the estimation method of the cutting force for a conical tool under nanoscale depth of cut by molecular dynamics.

This study uses molecular dynamics to simulate the nanoscale cutting of a Cu single crystal by a conical diamond tool. Actual nanoscale straight-line cutting experiments were performed, and the experimental results are compared with the simulation results. The heaping of copper atoms is qualitatively quite consistent with the simulation result. This paper also proposes a nanoscale contact pressure factor (NCP factor) that is applicable to the probes at different tip radii. An estimation model of the cutting force for nanoscale cutting is established. This model can estimate the cutting force during actual nanoscale cutting. Actual nanoscale cutting experiments were performed for verification, and the difference between the cutting force estimated by this model and the actual force is very small.