Papers by Keyword: Atomic Force Microscope (AFM)

Abstract: In recent years, fatigue limit estimation based on dissipated energy has been introduced in various industries because of its time and cost effectiveness. However, the mechanism of energy dissipation and the relationship between energy dissipation and fatigue damage have not been investigated well. In this study, mechanism of energy dissipation is investigated in relation with formulation of slip bands for JIS type 316L stainless steel through observation of slip bands by optical microscope and atomic force microscope.

Abstract: Atomic force microscopy (AFM) and focused ion beam technique (FIB) were adopted to study the early stages of surface relief evolution in 316L steel and polycrystalline copper fatigued with constant plastic strain amplitudes at different temperatures (316L steel at 93, 173 and 573 K; copper at 83, 173 and 295 K). Qualitative and quantitative data on the morphology and shape of persistent slip markings (PSMs), occurrence of extrusions and intrusions and the kinetics of extrusion growth are reported. They are discussed in relation with recent physically based theories of surface relief formation leading to fatigue crack initiation.

Abstract: In order to analyze the ageing mechanism of oil-paper, the Atomic Force Microscope (AFM), which is one of the important instruments in nanometer area, was used in this paper for the analysis of the micro surface morphology, and a 3-D surface roughness analysis on the AFM image was presented. The AFM figures indicates that the molecular arrangement of the initial cellulose paper is close and ordered, some of the hexagonal mesh structures of the D-glucopyranose units were broken down after 100 days accelerated thermal ageing. The roughness analysis indicates that he fiber surface roughness parameter Sa increases with the deepening of ageing degree. Special attention should be paid on the increase in the surface roughness of insulation paper, as it will aggravate the oil streaming electrification when the paper is applied to the power transformers.

Abstract: Atomic force microscopy (AFM) is the useful tool for measuring the micro fabricated devices. Measuring sample surface with AFM, tip-induced distortions are serious problem for accurate measurement. In order to overcome this problem, many studies are reported to reconstruct surface image to original sample surface. We studied method of reconstruction technique of the AFM image by using estimated 3-D tip shape from the impulse response technique. To reconstruct the image of the sample surface, we used a morphological reconstruction process. We demonstrated how to obtain the 3-D tip from the using impulse response technique and then how to reconstruct the 3-D AFM image using estimated tip shape.

Abstract: A simple and cost effective method using a thermal oxidation process for synthesizing cupric oxide (CuO) nanostructures is demonstrated in this paper. Using elevated temperatures ranging from 100°C to 400°C, the optimum formation of CuO composition indicated by an X-ray diffraction (XRD) was obtained at 400°C. Then, the effects of gas flow rates (ranging from 1 to 10 kPa) on the formation of CuO nanorods were investigated using a field emission scanning electron microscope (FESEM). It was found that at higher gas flow rate, the formation of CuO nanorods was obviously observed. The current-voltage (I-V) characteristic obtained from an I-V measurement system shows that diode characteristic has been formed with threshold voltage (V_th) of 0.9 V and breakdown voltage (V_B) of-5 V. The mechanism of structural changes will be discussed in details.

Abstract: Due to involvement of various fields of engineering and bio researchers in nanoprojects and their need in achieving certain layout of nanoparticles (NPs) in many research studies, considerable attention is paid to nanomanipulation nowadays. The present experimental study employs Atomic Force Microscope (AFM) in order to push gold nanoparticles on a highly flat mica surface. A silicon probe in contact mode is used to both image and manipulate nanoparticles and Topo and L-R images have been obtained to show the successes of manipulation when proper conditions are fulfilled. The effect of AFM parameters such as applied force, scanning speed and number of pixels of image on nanomanipulation efficiency is investigated. Moreover, the tip is moved along a special path which can be set by software to study manipulation of nanoparticles aggregates. Finally, possible applications of nanomanipulation in nanomechanics, nanoelectronics, nanomaterials and bio-technology are reported and further experimental research works on nanomanipulation are proposed.

Abstract: With the rapid advancements in the field of nanoscience and nanotechnology, scanning probe microscopy has become an integral part of a typical R&D lab. Atomic force microscope (AFM) has become a familiar name in this category. The AFM measures the forces acting between a fine tip and a sample. The tip is attached to the free end of a cantilever and is brought very close to a surface. Attractive or repulsive forces resulting from interactions between the tip and the surface will cause a positive or negative bending of the cantilever. The bending is detected by means of a laser beam, which is reflected from the backside of the cantilever. Atomic force microscopy is currently applied to various environments (air, liquid, vacuum) and types of materials such as metal semiconductors, soft biological samples, conductive and non-conductive materials. With this technique size measurements or even manipulations of nano-objects may be performed. An experimental setup has been designed and built such that a commercially available Atomic Force Microscope (AFM) (Nanosurf AG, Easyscan 2) can be operated at cryogenic temperature under vacuum and in a vibration-free environment. The design also takes care of portability and flexibility of AFM i.e. it is very small, light weight and AFM can be used in both ambient and cryogenic conditions. The whole set up was assembled in-house at a fairly low cost. It is used to study the surface structure of nanomaterials. Important perovskite manganite Pr_0.7Ca_0.3MnO₃ thin films were studied and results such as morphology, RMS area and line roughness as well as the particle size have been estimated at cryogenic temperature.

Abstract: The surface roughness is a physical quantity of micro geometry error surface material used for assessment of processed composed of peak, valley and the spacing of the. Have a great influence on the parts usage. Generally speaking, the surface roughness is small, can improve the matching quality, reduce wear, extending the service life of parts, but the processing cost of parts will increase. Commonly used assessment parameters can be divided into height parameters, spacing and shape parameters (parameter) three series. Measurement methods are commonly used surface texture tester, optical surface profiler and atomic force microscope. This paper makes a comparative analysis on the different measurement methods.

Abstract: Derived the approximate relationship between minimum cutting thickness and tip radius, ratio of vertical load and shear force, friction coefficient between tip and sample. Wire was being processed by changing the load size. The critical load of chip formation and machining thickness were found from atomic force scan picture. Contrast tests were done by transforming the specimen. The experimental results are basically consistent with the derived values.

Abstract: In this paper self-assembled silicon nanodots have been grown on silicon substrate using radio-frequency magnetron sputtering system. This system were settled at varying experimental conditions such as substrate temperature, time of deposition, RF power and fixed argon flow rate. Then the surface roughness was measured by AFM which resulted average dots size of 113 nm. However, the presence of a small amount of grain atoms formed on the surface was confirmed using SEM measurement. The crystalline Si-NDs with (100) plane contributed sharp diffraction peak located at 69.5° was confirmed using XRD measurement. These results of Si-NDs structural properties support the possible growth technique of radio-frequency magnetron sputtering.