• Journal of the Korean Society for Precision Engineering
• /
• v.24 no.6
• /
• pp.105-112
• /
• 2007

Tungsten wire micro electrochemical machining (W-wire micro ECM) with ultra-short pulses enables precise micro machining of metal. In wire micro ECM, platinum wire has been used because it is electrochemically stable. However, the micro metal wire with low strength is easily deformed by hydrogen bubbles which are generated during the machining. The wire deformation decreases the machining accuracy. To reduce the influence of hydrogen bubbles, in this paper, the use of tungsten wire was investigated. To improve machining accuracy, suitable pulse conditions which affect generation of bubbles were also investigated. The tungsten wire micro ECM can be applied to the fabrication of various shapes. Using this method, various micro-parts and shapes were fabricated.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2007.06a
• /
• pp.641-642
• /
• 2007

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.5 s.170
• /
• pp.37-44
• /
• 2005

In this paper, wire electrochemical machining (Wire ECM) with ultra short pulses is presented. Platinum wire with $10{\mu}m$ diameter was used as a tool and 304 stainless steel was locally dissolved by electrochemical machining in 0.1M $H_{2}SO_4$ electrolyte. Wire ECM can be easily applied to the fabrication of arbitrarily shaped micro-grooves without tool wear. The change of machining gap according to applied pulse voltage, pulse on-time and pulse period was investigated and the optimal pulse condition for stable machining was obtained. Using this method, various micro-grooves with less than $20{\mu}m$ width were fabricated.

• Korean Chemical Engineering Research
• /
• v.57 no.5
• /
• pp.730-734
• /
• 2019

Thermophoresis is a transport phenomenon of particles driven by a temperature gradient of a medium. In this paper, we discuss the thermophoresis of particles in microfluidic channels. In a non-fluidic, stagnant channel, the thermophoretic transport of micro-particles was found to be larger in proportion to the voltage applied to the platinum wire heat source installed in the channel. The variation of the temperature around the platinum wire depending on the voltage was estimated, by using the Callendar-van Dusen equation. The thermophoretic behavior of nano-particles in the same system was observed, which is similar to that of the microparticles. Finally, we fabricated a Y-shaped microfluidic channel with a platinum wire heat source installed in the channel, to realize the thermophoretic phenomenon of the particles in the suspension flowing through the channel. It is shown that the flow of the suspension can be controlled based on the thermophoretic principle.

• Journal of the Korean Chemical Society
• /
• v.11 no.3
• /
• pp.81-84
• /
• 1967

A simple rotating micro mercury electrode is constructed in such a way that the mercury surface can be renewed quite easily with reasonable reproducibility. It consists of a glass capillary of about 1mm diameter connected to a mercury filled tube by means of a ground joint that allows mercury flow at a particular relative position only, and the electrical connection between the two parts is made by a platinum wire fused in the bottom of the latter. Thus the mercury surface exposed at the tip of the capillary replaces the platinum tip of the usual platinum micro electrode; however, the capillary has to be bent so that the tip directs upwards. It has been found to be a convenient electrode in the amperometric titration in strongly acidic media. Furthermore, it has been advantageously used in the alternating-current polarography because of its smaller electrical resistance than the ordinary dropping mercury electrodes. It also can be used as a stationary mercury electrode in fast scanning polarography.

• Journal of the Korean Chemical Society
• /
• v.33 no.4
• /
• pp.399-405
• /
• 1989

The dependence of voltammetric parameters on the pressure for the reduction of Cu(II) in 0.5M KCl aqueous solution has been studied. In this system micro platinum electrode, standard calomel electrode and a helix type of platinum wire were used as the working, the reference and the auxilary electrode, respectively. With increasing the pressure from 1 to 1,800 bars, the half wave potentials of first reduction wave are shifted to the more negative potentials. And the diffusion currents of first and second reduction wave become considerably larger with increase in pressure from 1 to about 1,000 bars but are getting smaller beyond 1,000 bars. The good linear relationships between diffusion current and the concentrations of Cu(II) are established over all pressure range($1{\sim}1,800$ bars). The reversibility of the each reduction step is not changed with increasing pressure.