• Title/Summary/Keyword: Ablation

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Rapid Manufacturing of 3D Micro Products by UV Laser Ablation and Phase Change Filling (UV 레이저 어블레이션과 상변화 충진을 이용한 3차원 마이크로 부품의 쾌속 제작)

  • 신보성;김재구;장원석;황경현
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.26-29
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    • 2003
  • UV laser micromachining are generally used to create microstructures for micro product through a sequence of lithography-based photopatterning steps. However, the micromachining process is not suitable for the rapid realization of complex microscale 3D product because it depends on worker experiences, excessive cost and time to make many masks. In this paper, the more effective micro rapid manufacturing process, which is developed upon the base of laser micromachining. is proposed to fabricate micro products directly using UV laser ablation and phase change filling. The filling process is useful to hold the micro product during the next ablation step. The proposed micro rapid manufacturing process is also proven experimentally that enables to fabricate the 3D microscale products of UV sensitive polymer from 3D CAD data to functional micro parts.

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Excimer laser micromachining of silicon in liquid phase (액상에서의 엑시머 레이저 실리콘 미세가공)

  • Jang, Deok-Suk;Kim, Dong-Sik
    • Laser Solutions
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    • v.11 no.1
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    • pp.12-18
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    • 2008
  • Laser micromachining is a promising technique to fabricate the micro-scale devices. However, there remains important challenges to reducethe redeposition of ablated materials around the laser irradiated zone and to get a smooth surface, especially for metal and semiconductor materials. To achieve the high-quality micromachined devices, various methods have been developed. Liquid-assisted micromachining can be a good solution to overcome the previously mentioned problems. During the laser ablation process, the liquid around the solid sample dramatically changes the ablation characteristics, such as ablation rate, surface profile, formation of debris, and so on. In this investigation, we conducted the laser micromachining of Si in various liquid environmental conditions, such as liquid types, liquid thickness. In addition, using nanoscale time-resolved shadowgraphy technique, we observed the ablation process in liquid environments to understand the mechanism of liquid-assisted laser micromachining.

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Analysis for the Coolability of the Reactor Cavity in a Korean 1000 MWe PWR Using MELCOR 1.8.3 Computer Code

  • Lee, Byung-Chul;Kim, Ju-Yeul;Chung, Chang-Hyun;Park, Soo-Yong
    • Proceedings of the Korean Nuclear Society Conference
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    • 1996.05b
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    • pp.669-674
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    • 1996
  • The analysis for the coolability of the reactor cavity in typical Korean 1000 MWe Nuclear Unit under severe accidents is performed using MELCOR 1.8.3 code. The key parameters molten core-concrete interaction(MCCI) such as melt temperature, concrete ablation history and gas generation are investigated. Total twenty cases are selected according to ejected debris fraction and coolant mass, The ablation rate of concrete decreases as mass of the melt decreases and coolant mass increases. Heat loss from molten pool to coolant is comparable to total decay heat, so concrete ablation is delayed until water is absent and crust begins to remove. Also, overpressurization due to non-condensible gases generated during corium and concrete interacts can cause to additional risk of containment failure. It is concluded that flooded reactor cavity condition is very important to minimize the cavity ablation and pressure load by non-condensible gases on containment.

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Rapid Manufacturing of 3D Micro Products by UV Laser Ablation and Phase Change Filling (UV 레이저 어블레이션과 상변화 충진을 이용한 3차원 마이크로 부품의 쾌속 제작)

  • Shin B. S.;Kim J. G.;Chang W. S.;Whang K. H.
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.11 s.176
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    • pp.196-201
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    • 2005
  • UV laser micromachining are generally used to create microstructures for micro product through a sequence of lithography-based photopatterning steps. However, the micromachining process is not suitable for the rapid realization of complex 3D micro product because it depends on worker experiences, excessive cost and time to make many masks. In this paper, the more effective micro rapid manufacturing process, which is developed upon the base of laser micromachining, is proposed to fabricate micro products directly using UV laser ablation and phase change filling. The filling process is useful to hold the micro product during the next ablation step. The proposed micro rapid manufacturing process is also proven experimentally that enables to fabricate the 3D micro products of UV sensitive polymer from 3D CAD data to functional micro parts.

The effect of laser energy on the preparation of iron oxide by a pulsed laser ablation in ethanol

  • Maneeratanasarn, P.;Khai, T.V.;Choi, B.G.;Shim, K.B.
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.22 no.3
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    • pp.134-138
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    • 2012
  • Recently the preparation magnetic nanoparticles by a pulsed laser ablation in liquid has gained much attention because it is easy to control experimental parameters. Iron oxide magnetic nanoparticles have been prepared by a pulsed laser ablation of ${\alpha}-Fe_2O_3$ target in ethanol at different magnitude of laser energy of 1, 20, 40 and 80 mJ/pulse. It revealed that particle size increases with increasing laser energy. It could be concluded that 40 mJ/pulse is an optimum laser energy for the preparation of iron oxide nanoparticles with uniform size distribution. The nanoparticles are homogeneously dispersed in ethanol and their stability maintained for several months.

Micromachining Modelling and Simulation for Microlens Using Excimer Laser (액시머 레이저를 이용한 마이크로 렌즈 가공 모델링 및 시뮬레이션)

  • 최경현;배창현
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.13 no.1
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    • pp.55-62
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    • 2004
  • This paper addresses the method for figuring out the hole diameter on the mask containing the information about machining depth. With this mask e micro machining is carried out with a simple 2D movement of the mask. Based on e suggested method excimer laser ablation processes are modeled and determination of the optimal laser ablation conditions such as hole diameter, step size, mask movement velocity, etc. is completed. The excimer laser ablation simulation for creating 3D micro lens is carried out by employing determined ablation conditions to prove verification of the method. The results from simulation illustrated the average error of 140nm and e relative error of 2%.

Optical Properties of Silicon Nanoparticles and $C_{60}$ Thin Films Prepared by Pulsed Laser Ablation (Pulsed Laser Ablation으로 제작한 $C_{60}$ 및 Si 박막의 광학적 특성 분석)

  • Kim, M.S.
    • Journal of Power System Engineering
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    • v.9 no.4
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    • pp.118-123
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    • 2005
  • We have investigated the fabrication of Si nanoparticles and $C_{60}$ thin films by pulsed laser ablation. By atomic force microscopy(AFM), the laser-deposited $C_{60}$ thin film was verified to have surface far smoother than the surfaces of films produced by the conventional evaporation method. The Si deposited at a He atmosphere of 0.2 Torr was with about $60{\AA}$ height of the Si nanoparticles, suggesting that it was uniformly deposited. We observed visible green emissions spectra in the $Si/C_{60}$ multilayer films after laser annealing. It is considered that this green emissions is occurred from SiC particles, which is produced reaction of Si nanoparticles with $C_{60}$ by laser annealing.

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Evaluation of Mechanical Characteristic of Laser-Welded Blank of a Boron Steel by Using Laser Ablation of Al-Si Coating Layer (Al-Si 코팅층 Laser Ablation 변수에 의한 LWB 보론강판의 기계적 특성 평가)

  • Moon, J.H.;Lee, M.S.;Kang, C.G.
    • Transactions of Materials Processing
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    • v.20 no.8
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    • pp.540-547
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    • 2011
  • Recent years have seen advent of hot stamped parts made from laser-welded blanks of boron steels for structures requiring high crash energy absorption. However, the presence of Al-Si coating interfered with satisfactory mechanical characterizations after laser butt welding. In this study, laser ablation technology was considered in order to facilitate adequate mechanical characterization of the final hot-stamped panels.

Characteristic of FS-laser ablation of metal thin film with respect to the variation of material and substrate (펨토초 레이저를 이용한 박막 재료 및 기판 변화에 따른 가공 특성에 관한 연구)

  • Kim B.H.;Shin H.G.;Lee J.G.;Jeong S.C.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2006.05a
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    • pp.671-672
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    • 2006
  • We have investigated the behavior of the ultrafast laser ablation of chromium films (200nm) on the silicon and pyrex-glass(corning 7740) substrate with respect to the laser fluence and the number of laser pulses. In addition, several experiments about ITO thin film were carried out with femto-second Ti:Sapphire laser (150fs). Finally, we introduce the ablation characteristic in accordance with materials of thin film and substrate.

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Micro-machining of nickel by picosecond laser ablation (피코초 레이저를 이용한 니켈의 미세가공 특성)

  • Shin D.S.;Lee J.H.;Suh J.;Noh J.W.;Chung Y.W.;Kim J.C.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2006.05a
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    • pp.653-654
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    • 2006
  • In case of ultrashort laser ablation of metals, the transfer of energy from the electronic system causing strong absorption of laser light to the lattice needs relaxation times of the order of some picoseconds. Under the above theoretical background, nickel was ablated using femtosecond, picosecond and nanosecond laser. As a result, nickel ablation by picosecond laser and femtosecond laser, which are called ultrashort laser, has similar machinability because of relaxation time of metals, whereas nanosecond Nd:YAG laser has lower absorption, higher thermalization effect in comparison with ultrashort laser.

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