• 제목/요약/키워드: crystal orientation

검색결과 563건 처리시간 0.03초

분자동역학을 이용한 나노구조물의 크기와 결정방향에 따른 응력-변형률 관계 해석 (Analysis of Stress-Strain Relationship of Nano Structures According to the Size and Crystal Orientation by Using the Molecular Dynamics Simulation)

  • 강용수;김현규
    • 대한기계학회논문집A
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    • 제32권12호
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    • pp.1047-1054
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    • 2008
  • In this paper, the molecular dynamics (MD) simulations are performed with single-crystal copper blocks under simple shear and simple tension to investigate the effect of size and crystal orientation. There are many variances to give influences such as deformation path, temperature, specimen size and crystal orientation. Among them, the crystal orientation has a primary influence on the volume averaged stress. The numerical results show that the volume averaged shear stress decreases as the specimen size increases and as the crystal orientation changes from single to octal. Furthermore, the Schmid factor and yield stress for crystal orientation are evaluated by using the MD simulation on the standard triangle of stereographic projection.

Al-Mg-Si계 알루미늄 합금 판재 마찰교반접합부의 결정 방위 분포에 대한 용접후열처리의 영향 (Effect of Post Weld Heat Treatment for Crystal Orientation Distribution on Friction Stir Welds of Al-Mg-Si Series Aluminum Alloy Sheets)

  • 이광진
    • Journal of Welding and Joining
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    • 제27권6호
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    • pp.62-67
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    • 2009
  • Friction stir welding (FSW) was carried out for Al-Mg-Si series aluminum alloys which are being used for automotive body structure. Consequently, Post weld heat treatment (PWHT) was applied to the friction stir welds to evaluate the effect of the paint baking process which is one of the automotive fabrication process on friction stir welded zone (FSWZ) in 443K for 1.2Ks. Grain structure and its crystal orientation distribution was measured about both the as welded specimens and the post weld heat treated specimens. An optical microscope (OM) and an field emission scanning electron microscope (FE-SEM) was used for observing the grain structure and measuring its crystal orientation distribution, respectively. Changes on the grain structure and its crystal orientation distribution were not detected. From the present results, it was confirmed that the paint baking process after FSW do not affect on the grain structure and its crystal orientation distribution of FSWZ. The comprehensive investigations will be performed for various automotive aluminum alloys manufactured by different processes, in the future.

Strong Orientation Anchoring and Shear Flow of a Nematic Liquid Crystal

  • Won Hee HAN
    • International journal of advanced smart convergence
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    • 제13권2호
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    • pp.103-109
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    • 2024
  • A nonlinear numerical analysis of orientation and velocity fields of the full Ericksen-Leslie theory for a nematic liquid crystal under shear flow is given. We obtained for the first time the three-dimensional orientation and two component velocity profiles evolutions for both in- and out-of-shear plane orientation anchorings. Complex evolution routes to steady state were found even for shear aligning nematic. As the Ericksen number increases monotonic evolution of velocity and orientation shifts towards multi-region nucleating director rotation growth with complex secondary flow generations. We found that contrary to the in-shear-plane anchorings like homeotropic or parallel anchorings, binormal anchoring gives rise to substantial non-planar three-dimensional orientation with nonzero secondary flow.

섬유상 분말로 제조된 배향성을 가진 $BaTiO_3$ 세라믹 (Oriented Barium Titanate Ceramics Made from Fiber State Powder)

  • 서용교;야나기다히로아끼
    • 한국세라믹학회지
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    • 제30권12호
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    • pp.1066-1070
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    • 1993
  • When looked upon as a polycrystalline, ceramics have two basic differences from a single crystal. One is that there exist grain boundaries, the other is that the crystal axes of each small crystal are arranged in random directions. But the crystal axes fo small crystals which compose ceramics may be made to have the tendency of being arranged in a specific direction. This is called that the crystal axes are oriented. The degree of the direction arrangement of the crystal axes is called orientation. In order to orient the crystal axes effectively, the fiberous barium titanates were made through KDC method and the ion exchange method. And then they were arranged through pressing, doctor blade, and syringe. As the result of Lotgering evaluation, the sample oriented through syringe showed the highest orientation. After sintering, though the most particles that had been fiberous shaped became global shape viewed through SEM, the orientation of the crystals was reinforced by means of sintering.

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물리증착법에 의해 제작한 마그네슘 박막의 형성기구와 내식특성 (Formation Mechanism and Corrosion-Resistance of Magnesium Film by Physical Vapour Deposition Process)

  • 이명훈
    • Journal of Advanced Marine Engineering and Technology
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    • 제18권2호
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    • pp.54-63
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    • 1994
  • Mg thin films were prepared on SPCC(cold-rolled steel) substrates by vasuum evapoaration and ion-plating. The influence of argon gas pressure and substrates bias voltage on the crystal orientation and morphology of the film was determined by using X-ray diffraction and scanning electron micrography (SEM), respectively. And the effect of crystal orientation and morphology of the Mg thin films on corrosion behavior was estimated by measuring the anodic polarization curves in deaerated 3% NaCl solution. The crystal orientation of the Mg films deposited at high argon gas pressure exhibited a (002) preferred orientation, regardless of the substrate bias voltage. Film morphology changed from a columnar to a granular structure with the increase of argon gas pressure. The morphology of the films depended not only on argon gas pressure but also bias voltage ; i.e., the effect of increasing bias voltage was similar to that of decreasing argon gas pressure. The influences of argon gas pressure and bias voltage were explained by applying the adsorption inhibitor theory and the sputter theory. And also, this showed that the corrosion resistance of the Mg thin films can be changed by controlling the crystal orientaton and morphology.

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Magnesium Thin Films Possessing New Corrosion Resistance by RF Magnetron Sputtering Method

  • Lee, M.H.;Yun, Y.S.;Kim, K.J.;Moon, K.M.;Bae, I.Y.
    • Corrosion Science and Technology
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    • 제3권4호
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    • pp.148-153
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    • 2004
  • Magnesium thin flims were prepared on cold-rolled steel substrates by RF magnetron sputtering technique. The influence of argon gas pressure and substrate bias voltage on their crystal orientation and morphology of the coated films were investigated by scanning electron microscopy (SEM) and X-ray diffraction, respectively. And the effect of crystal orientation and morphology of magnesium films on corrosion behaviors was estimated by measuring anodic polarization curves in deaerated 3%NaCl solution. From the experimental results, all the sputtered magnesium films showed obviously good corrosion resistance to compare with 99.99% magnesium target of the sputter-evaporation metal. Finally it was shown that the Corrosion-resistance of magnesium films can be improved greatly by controlling the crystal orientation and morphology with effective use of the plasma sputtering technique.

대향타겟식 스퍼터법으로 제작한 $Ni_{81}Fe_{19}$박막의 결정배향성 (Crystal orientation of $Ni_{81}Fe_{19}$ thin film prepared by facing targets sputtering method)

  • 김용진;박창옥;최동진;김경환
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2000년도 하계학술대회 논문집
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    • pp.185-188
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    • 2000
  • Crystal orientation of Ni$_{18}$ $Fe_{19}$ thin films prepared by facing targets sputtering system was investigated. FTS system can deposit a high quality thin film and control deposition conditions in wide range. T he crystallographic characteristics of Ni$_{18}$ $Fe_{19}$ thin films on variation of thickness and substrate tempera ture was investigated by XRD and AFM. As a result, we obtained Ni$_{18}$ $Fe_{19}$ thin films prepared at subst rate temperature room temperature, thickness 160nm and over revealed good crystal orientation to [111] direction.irection.

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Effect of heat-treatment on the structural and electrical properties of ZnO thin films by the sol-gel method

  • Lee, Seung-Yup;Park, Byung-Ok
    • 한국결정성장학회지
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    • 제18권2호
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    • pp.72-75
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    • 2008
  • Zinc oxide (ZnO) thin films were prepared by a sol-gel method. The structural and electrical properties were investigated by varying drying and annealing temperatures. The thin films were coated (250 nm) by spin-coating method on glass substrates. The optimum drying temperature of ZnO thin films was 300$^{\circ}C$ where the resistivity was the lowest and the preferred c-axis orientation was the highest. The annealing was carried out in air and inert atmospheric conditions. The degree of the preferred c-axis orientation was estimated. The highest preferred c-axis orientation was recorded at 600$^{\circ}C$. The preferred c-axis orientation and grain growth resulted in the mobility enhancement of the ZnO thin films, and the lowest resistivity was 0.62${\Omega}{\cdot}cm$ at 600$^{\circ}C$.

AC PDP의 MgO 결정방향성과 증착조건간의 상관관계에 관한 연구 (The relationships between the MgO crystal orientation and the conditions of deposition on AC-PDP)

  • 장진호;장용민;이지훈;조성용;김동현;박정후
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2006년도 추계학술대회 논문집 전기물성,응용부문
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    • pp.202-203
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    • 2006
  • In the AC PDP, the MgO film is used as electrode protective film. This film must provide excellent ion bombardment protection, high secondary electron emission, and should be high transparent to visible radiation. In this study, we investigated the relations between the crystal orientation and e-beam evaporation process parameters. The crystal orientation of the MgO layer depends on the conditions of deposition. The parameters are the thickness of the MgO film $1000{\AA}-6500{\AA}$, the deposition rate $200{\AA}/min{\sim}440{\AA}/min$, the temperature $150^{\circ}C{\sim}250^{\circ}C$, and the distance between crucible and substrate 11cm ${\sim}$ 14cm. The temperature of substrate and evaporation rate of source material, or deposition rate of the film, are definitely related to the crystal orientation of the MgO thin film. The crystal orientation can be changed by the distance between the target(MgO tablet) and the substrate. However, the crystal orientation is not much affected by the thickness of MgO thin film.

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라우에 배면반사법을 이용한 PMN-PT 단결정 성장 방향 분석 (An Analysis of the Growing Orientation of PMN-PT Single Crystal Using the Laue Back-Reflection Method)

  • 조치영;서희선;권병진;이원옥;이상구;김민찬
    • 한국전기전자재료학회논문지
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    • 제28권12호
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    • pp.787-791
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    • 2015
  • In this paper, the growing orientation of PMN-PT single crystal is analyzed using the Laue-Back Reflection Method. Two kinds of PMN-PT single crystals are grown using the Bridgman growing method in the [001] and [111] directions and their the Laue photographs are simulated assuming cubic crystal systems. From the comparison between simulation and test results, it can be concluded that the single crystals are grown in the desired crystal orientations.