• Title/Summary/Keyword: Tungsten tip

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Development of Nonthermal Bioplasma Source Applicable to Human Liquid Fluids

  • Min, Boo-Ki;Oh, Hyun-Joo;Song, Ki-Baek;Uhm, Han-Sup;Kang, Seung-Oun;Choi, Eun-Ha
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.08a
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    • pp.327-327
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    • 2011
  • A nonthermal bioplasma source was developed for application to human liquid fluids by making use of nano-size tungsten tips. Characteristics of the plasma source are investigated. Here we have used the AC voltage system. The bioplasma source generated by a tungsten tip with quartz tube and ground electrode is a low-temperature plasma without making any noticeable damage to cells at a low power operation. The breakdown voltage and current signals are measured by high voltage probe (Tektronix P6015A) and current probe (P6021). Variation of breakdown temperature near the tip electrode is larger than that in the neighborhood of ground electrode. Bubble formation during discharge has been recorded and investigated by using the high speed camera. The existence and behavior of hydroxyl and superoxide radicals are detected and measured by spectrometers. The electrical and optical properties of breakdown characteristics are also investigated.

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A Study on the Bead Stability in High Speed TIG Welding (고속 TIG 용접의 비드 안정성에 관한 연구)

  • 조상명
    • Journal of Advanced Marine Engineering and Technology
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    • v.18 no.3
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    • pp.68-77
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    • 1994
  • TIG welding process is applied for the active metal such as aluminum and titanium, also sometimes for overlay welding of superalloy. However the welding speed to be applied is very low because of the unstable bead formed in the region of high current and high welding speed. The present study was carried out to examine the basic phenomena of high speed TIG melt run welding by the 2% Th - W electrode(dia.3.2mm) of various tip shapes.

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A study on the erosive wear of spray tip nozzle by epoxy primer paint impingement and the spraying characteristics (에폭시 프라이머 도료의 에어리스 스프레이 분사 시간에 따른 팁 노즐 침식마모경향과 분사특성 연구)

  • Kim, Jinuk;Cho, Yeon-Ho;Cheon, Je-Il;Han, Myoung-Soo
    • Corrosion Science and Technology
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    • v.14 no.2
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    • pp.59-63
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    • 2015
  • Airless spray which is widely used for painting to ship blocks and hull sides is the coating method for attaching atomized paint material to the substrate using spray tip nozzle with compressed air. When the paint material which has high solid contents such as epoxy primer paint is atomized by passing through spray tip nozzle with high pressure, the nozzle composed of tungsten carbide(WC) undergoes the erosive wear, leading to widening of nozzle hole. The deformation of nozzle hole induces improper spray pattern and coating failures such as finger pattern and sagging because the conditions of spray pump pressure and paint flow rate for developing full spray pattern are changed. In this study, an appropriate replacement cycle of spray tip was predicted by measuring the erosive wear tendency as increasing the spraying time of epoxy primer paint.

A Study on the Influence of Atmospheres in Frictional Machining(Part II) (摩찰加工 에 있어서의 零圍氣 영향 에 관한 硏究 제2보)

  • 손명환
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.6 no.2
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    • pp.113-120
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    • 1982
  • In the previously reported Part I, the experimental results in frictional machining that finished medium carbon steel SM 50 C under 6 kinds of liquid atmospheres by using ceramic tip as a frictional tool was described. The present study reports the experimental results that all the machining conditions are same in the Part I except tool material changed ceramics into tungsten carbide. The ceramic tool material is a stable oxide and a non-metallic material, but the tungsten carbide has the metallic characteristics that adhere to carbon steel at about 750.deg.C. The present study shows th comparison of the experimental results for the above 2 kinds of frictional tool material.

Effect of the Mechanical Properties of Disk Material on the Cut-off Characteristics of Tungsten Carbide Tipped Circular Saw (초경팁 부착형 둥근톱의 절단 특성에 미치는 기판 재질의 영향)

  • Lee, Jae-Woo
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2001.04a
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    • pp.883-886
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    • 2001
  • The mechanical properties such as the Young's modulus, damping ratio, vibration mode and hardness of the disk materials heat-treated under various conditions are measured, and the relations between there properties and the cutting characteristics such as early tip fracture are examined. The results obtained from this study are as follows. The circular saw with the V-Cr added disk has higher young's modulus and damping ratio than the saw with STC5 disk, preventing the early fracture of tungsten carbide due to the above properties. The circular saw with the disk which is subjected to the heat treatment at the quenching temperature of $830^{\circ}C$ and at the temperature of $550^{\circ}C$ have the best tool life and surface roughness.

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The development of high wear resistant tappet in diesel engine (Diesel Engine용 내마모 초경 Tappet 개발)

  • 송근철;심동섭;김경운;조정환
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1998.10a
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    • pp.313-322
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    • 1998
  • Tappet has wear problems like scuffing or pitting because of high Hertzian contact stress by line contact type between cam and tappet. To overcome this wear problems, we developed the high wear resistant tappet. Developed tappet consists of WC base alloyed tip and steel body. These two parts were directly bonded each other at high temperature under vacuum condition. To estimate the wear resistance of tungsten carbide tappet, we perform the scuffing test and engine dynamo test. As the result, tungsten carbide tappet has better wear resistance than conventionally chilled iron tappet.

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Epoxylite Influence on Field Electron Emission Properties of Tungsten and Carbon Fiber Tips

  • Alnawasreh, Shady S;Al-Qudah, Ala'a M;Madanat, Mazen A;Bani Ali, Emad S;Almasri, Ayman M;Mousa, Marwan S
    • Applied Microscopy
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    • v.46 no.4
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    • pp.227-237
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    • 2016
  • This investigation deals with the process of field electron emission from composite microemitters. Tested emitters consisted of a tungsten or carbon-fiber core, coated with a dielectric material. Two coating materials were used: (1) Clark Electromedical Instruments Epoxylite resin and (2) Epidian 6 Epoxy resin (based on bisphenol A). Various properties of these emitters were measured, including the current-voltage characteristics, which are presented as Fowler-Nordheim plots, and the corresponding electron emission images. A field electron microscope with a tip (cathode) to screen (anode) distance of 10 mm was used to electrically characterize the emitters. Measurements were carried out under ultra-high vacuum conditions with a base pressure of $10^{-6}$ Pascal ($10^{-8}$ mbar).

Work Function Change of W(123) Plane Due to Hydrogen and Deuterium Adsorption at 78K (78K에서 수소 혹은 중수소 흡착으로 인한 W(123)면의 일함수 변화)

  • 박노길;김기석;김성수;정광호;황정남;최대선
    • Journal of the Korean Vacuum Society
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    • v.1 no.1
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    • pp.78-82
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    • 1992
  • The changes in work function due to hydrogen and deuterium adsorption on W(123) plane are measured by means of Field Emission Method. In the case of hydrogen or deuterium adsorption, work function of W(123) plane at 78 K increase and after a maxium value, it decrease and saturated as increasing coverage. After annealing the tungsten emission tip at 200 K, the coverage corresponding to maximum change in work function was shifted toward low coverage and the effect of work function by terraces or steps of which orientation is [ O l l ] was observed.

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Effect of Contact Conditions on the Micro-adhesion Characteristics using SPM (SPM을 이용한 접촉조건 변화에 따른 미소응착 특성 연구)

  • 윤의성;박지현;양승호;공호성
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2000.11a
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    • pp.18-22
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    • 2000
  • An experimental study was carried out to investigate the effect of nano-contact condition on the nano-adhesion phenomena. SPM(scanning probe microscope) tips with different radius of curvature were fabricated by a series of masking and etching processes. DLC(diamond-like carbon) and W-DLC (tungsten-incorporated diamond-like carbon) were coated on (100) silicon wafer by PACVD(plasma assisted chemical vapor deposition). Pull-off forces of Pure Si-wafer, DLC and W-DLC were measured with SPM(scanning probe microscope). Also, the same series of tests were carried out with the tips with different radius of curvature. Results showed that DLC and W-DLC showed much lower pull-off force than Si-wafer and Pull-off force increased with the tip radius.

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Field-emission characteristics of carbon nanotube emitters in terms of tip angles of conical-type metal substrates (원추형 금속 기판의 팁 각도에 따른 탄소 나노튜브 이미터의 전계방출 특성)

  • Kim, Jong-Pil;Noh, Young-Rok;Chang, Han-Beet;Park, Jin-Seok
    • Journal of the Semiconductor & Display Technology
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    • v.10 no.2
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    • pp.115-119
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    • 2011
  • A tip-type carbon nanotube(CNT)-based field emitter was studied to consider it as electron source for micro-focused x-ray tube. The CNT was grown directly on a metal (tungsten) substrate by using an inductively coupled plasma-chemical vapor deposition (ICP-CVD) method. Prior to CNT growth, the metal substrate was etched to have various tip angles from $10^{\circ}$ to $180^{\circ}C$ (flat-type). The morphologies and microstructures of all the grown CNTs were analyzed via field-emission SEM. Furthermore, the effects of substrate tip-angles on the emission properties of CNT-based field emitters were characterized to estimate the maximum current density, the turn-on voltage, and the spatial distribution of electron beams. Prolonged long-term stability testing of the CNT emitters was also performed. All the experiment results obtained from this study indicated why a tip-type CNT emitter, compared with a flat-type CNT emitter, would be more desirable for a micro-focused x-ray system, in terms of the emission current level, the focused beam area, and the emission stability.