Accepted Manuscripts

Jonghyun Kim, Dongwoon Shin, Kyu-Bum Han and Jiyoung Chang
J. Micro Nano-Manuf   doi: 10.1115/1.4039794
Electrospinning, one of the most effective ways of producing nanofibers, has been applied in as many fields throughout its long history. Starting with far-field electrospinning and advancing to the near-field, the application area has continued to expand, but lack of understanding of the exact jet speed and fiber deposition rate is a major obstacle to entry into precision micro to nanoscale manufacturing. In this paper, we, for the first time, analyze and predict the jet velocity and deposition rate in near-field electrospinning through novel image analysis process. Especially, analog image is converted into a digital image, and then the area occupied by the deposited fiber is converted into a velocity, through which the accuracy of the proposed method is proved to be comparable to direct jet speed measurement. Finally, we verified the proposed method can be applied to various process conditions without performing delicate experiments. This research not only will broaden the understanding of jet speed and fiber deposition rate in NFES but also will be applicable to various areas including patterning of the sensor, a uniform arrangement of nanofibers, energy harvester, reinforcing of composite and reproducing of artificial tissue.
TOPICS: Electrospinning, Image processing, Nanofibers, Fibers, Sensors, Manufacturing, Biological tissues, Nanoscale phenomena, Energy harvesting, Composite materials
Soham S. Mujumdar, Davide Curreli and Shiv G Kapoor
J. Micro Nano-Manuf   doi: 10.1115/1.4039508
Electrical conductivity of the dielectric liquid has been shown to play main role in discharge initiation and electrical breakdown as revealed by several modeling and experimental studies on electrical discharges in liquids. However, there has been lack of systematic efforts to evaluate how dielectric conductivity affects the micro-EDM process, in particular. Experimental investigation has been carried out to understand the effect of dielectric conductivity on micro-EDM plasma characteristics using optical emission spectroscopy (OES). Plasma temperature and electron density estimations have been obtained at five levels of electrical conductivity of water. It is found that while the plasma temperature shows a marginal decrease, electron density of the plasma increases with an increase in the conductivity. At increased electron density, a higher heat flux at anode can be expected resulting in an increased material erosion.
TOPICS: Electrical conductivity, Plasmas (Ionized gases), Emission spectroscopy, Electrical discharge machining, Density, Electrons, Temperature, Anodes, Breakdown (Electricity), Erosion, Modeling, Dielectric liquids, Water, Heat flux
Xiuqing Hao, Hanlong Li, Xiaolu Song, Liang Li and Ning He
J. Micro Nano-Manuf   doi: 10.1115/1.4039481
The micro/nanotextured cemented carbide surface of different wettability was produced by laser scanning and fluorinated treatment. The tribological properties of the untextured, oleophobic and oleophilic micro/nanotextured surface were investigated experimentally including the effects of crank speed and contact pressure by a reciprocating friction and a wear tester. For all tested surfaces, the friction coefficient of the surface decreased as both the increasing crank speed and contact pressure increased. Compared to the untextured surface, the friction coefficient of the micro/nanotextured surface was significantly decreased, being sensitive to the wettability of the surface. Besides, the tribological properties of the oleophobic micro/nanotextured surface were superior to the oleophilic micro/nanotextured surface under the same experimental conditions. The improvement in tribological properties of the oleophobic micro/nanotextured surface could be attributed to the low wettability, which was beneficial to rapid accumulation of the lubricating oil on the surface.

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