• 한국진공학회지
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• 제12권S1호
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• pp.21-27
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• 2003

Micro-arc discharge oxidation (MDO) is a cost-effective plasma electrolytic process which can be used to improve the wear and corrosion resistance of Al-alloy parts by forming a alumina coating on the component surface. However, the MDO coated Al-alloy components often exhibit relatively high friction coefficients and low wear resistance fitted with many counterface materials, additionally, the pitting corrosion for the MDO coated AI-alloy components, especially for a thinner alumina coating, often occurs in atmosphere circumstance due to the porous alumina coats. Therefore, a duplex treatment, combining a MDO coated ahumina thin layer with a TiN coating, prepared by magnetron sputtering (MS), has been investigated. The Vicker's microhardness, pin-on-disc, electrochemical measurement, salt spray, XRD and SEM tests were used to characterize and analyze the treated samples. The work demonstrates that the MDO/MS coated samples have a combination of a very low friction coefficient and good wear resistance as well as corrosion since the micro-holes on alumina coating are partly or fully covered by TiN material.

• 한국표면공학회지
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• 제27권1호
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• pp.36-44
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• 1994

The TiN films were deposited on the stainless substrates using arc vapor ion deposition process to in-vestigated the wear resistance. Pin-on-disc tests were performed to measure the volume wear loss of TiN films. The substrate bias voltages and nitrogen flow rates were selected as the deposition parameters of TiN films. It was found that the wear resistance of TiN films was enhanced with increasing bias voltages(0~-300 V) and nitrogen flow rates(220~380 SCCM). The volume wear loss TiN films were about 9.5~2.1$\times$$10^{-3}mm^3$ and 3.5~2.2$\times$$10^{-3}mm^3$ with bias voltages and nitrogen flow rates, respectively.

• 한국전기전자재료학회논문지
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• 제32권5호
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• pp.407-412
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• 2019

In this paper, the changes in the electrical characteristics (arc energy, contact resistance, and bouncing phenomenon) due to the deterioration of the contact are analyzed. The results are generally consistent and can be analyzed for contact deterioration. The results of the experiment demonstrate that the arc energy is linearly related to the current when the contact samples and the voltage conditions are the same. The contact resistance varies due to multiple factors, but is generally within a certain range, and the contact deterioration can be determined. Contact stabilization can be detected by the decrease in the bouncing phenomenon due to deterioration (the change of the shape of the contact).

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 가을 학술논문 발표대회
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• pp.17-18
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• 2021

In the present study, Al-Zn coating was deposited by Arc thermal (AT) and plasma arc thermal (PAT) spray processes, and their corrosion characteristics were studied in 3.5% NaCl through electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM) and mechanical tests. The bond adhesion result showed that plasma arc sprayed coating had a higher value attributed to compact, dense, and less porous coating compared to arc thermal spray coating which contains defects/pores and uneven morphology as revealed by scanning electron microscope analysis. Electrochemical results revealed that the plasma arc sprayed coating had a high polarization resistance at early stage of immersion, suggesting its excellent corrosion protection performance.

• 한국정밀공학회지
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• 제21권12호
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• pp.44-51
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• 2004

In a micro-EDM, it is well known that an RC circuit is suitable as a discharge circuit because of its low pulse width and relatively high peak current. To increase machining speed without changing unit discharge energy, charge resistance should be decreased. But, when the resistance is very low, continuous (or normal) arc discharge occurs, electrode wear increases and machining speed is reduced remarkably. In this paper, an RC circuit with transistors is used in a micro-EDM. Experimental results show that the RC circuit with transistors can cut off a continuous (o. normal) arc discharge effectively if the duty factor and switching period of the transistor are set up optimally. Through experiments with varying charge resistances, it is shown that the RC circuit with transistors has about two times faster machining speed than that of an RC circuit.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.235-240
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• 2002

In micro-EBM, it is well blown that RC circuit is suitable for discharge circuit because of its low pulse width and relatively high peak current. To increase machining speed without changing unit discharge energy, charge resistance should be decreased. But, if very low, continuous (or normal) arc discharge occurs, then increases electrode wear and reduces machining speed remarkably. In this paper, RC circuit with transistor is used to micro-EDM. Experimental results show that RC circuit with transistor can cut off continuous (or normal) arc discharge effectively if duty factor and switching period of transistor are set up optimally. Through experiments with varying charge resistance, it can be known that RC circuit with transistor has about two times faster machining speed than that of RC circuit. Especially, it has prominent rise-effect of machining speed in low unit discharge energy, so that a high-quality and high-speed micro-EDM can be realized through RC circuit with transistor.

• 한국자동차공학회논문집
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• 제14권1호
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• pp.100-108
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• 2006

Time-resolved current and voltage measurements for an inductive automotive spark system were made. Also presented are measurements of the total energy delivered to the spark gap. The measurements were made in air for a range of pressures from 1-18atm, at ambient temperatures. The measured voltage and current characteristics were found to be a function of many ignition parameters; some of these include: spark gap distance, internal resistance of the spark plug and high tension wire, and pressure. The voltages presented were measured either at the top of the spark plug or at the spark gap. The measurements were made at different time resolutions to more accurately resolve the voltage and current behavior throughout the discharge process. This was necessary because the breakdown event occurs on a time scale much shorter than the arc and glow phases. The breakdown, are, and glow voltages were found to be functions of spark plug resistance, gas density, and spark plug gap as expected from the literature. Spark duration was found to decrease as either pressure or gap was increased. The transition from the arc to glow phase is usually distinguished by a sudden rise in the voltage across the gap. At pressures above about 7atm this transition was not observed suggesting that a glow phase was not present. Energy delivered to the gap increased with increasing pressure. The effective resistance of the spark gap during discharge was about twice as large for the glow phase as the arc phase.

• Journal of Welding and Joining
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• 제17권5호
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• pp.107-115
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• 1999

The objective of this research was to study the formation of the thick hardened layer with the addition of metal powder(Cu) and ceramics powders(TiC) on the aluminum 5083 alloys by plasma transferred arc process(PTA process) and to characterize the effect of overlaying conditions on the overlaid layer formation. This was followed by investigating the microstructures of the overlaid layers and mechanical properties such as hardness and wear resistance. The overlaid layer containing copper powder was alloyed and intermetallic compound($CuAl_2$) was formed. The overlaid layers with high melting point TiC powders, however, did not react with base metal. Wear resistance of the alloyed layer was remarkably improved by the formation of $CuAl_2$, precipitate phase, which prevented wear of base aluminum alloys and at higher wear speed, accelerated sliding of the counter part. Wear resistance of the composite layer was also remarkably improved because TiC powder act as a load barring element and Fe debris fragments detached from the counter part act as a solid lubricant on the contact surface.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권10호
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• pp.465-472
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• 2002

This paper presents a study on the aging and recovery of HTV (high temperature vulcanized) silicone rubber used for outdoor insulators. UV irradiation, corona discharge and water immersion were employed as factors of the artificial aging. The effects of changes derived from these stresses on the tracking and arc resistance of silicone rubber were examined. We have investigated the aging phenomena of HTV silicone rubber by the above stresses using the surface energy calculation with contact angle measurement, solvent-extraction, and surface/volume resistivity and so on. These results showed that UV irradiation and corona discharge lead to nearly the same surface oxidation, but the percentage change of mobile low molecular weight by these stresses was different. Furthermore, the oxidized layer induced under UV irradiation restricted the recovery of hydrophobic surface. Water immersion little lowered hydrophobicity level and leaded to a loss of tracking and arc resistance. The degradation mechanism based on our results was discussed.

• 전기학회논문지
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• 제57권3호
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• pp.494-500
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• 2008

This paper presents the analyzed result of the series arc fault current by using the discrete wavelet transform. The series arcing is caused by a loose connection in series with the load circuit. The series arc current is limited to a moderate value by the resistance of the device connected to the circuit, such as an appliance or a lighting system. The amount of energy in the sparks from the series arcing is less than in the case of parallel arcing but only a few amps are enough to be a fire hazard. Therefore, it is hard to detect the distinctive difference between a normal current and a intermittent arc current. This paper, presents the variation of the ratio of peak values and RMS values of the series arc fault current, and proposes the novel series arc fault detecting method by using the discrete wavelet transform. Loads such as a CFL lamp, a vacuum cleaner, a personal computer, and a television, which has the very similar normal current with the arc current, were selected to confirm the novel method.