• Title/Summary/Keyword: boron nitride

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Recent Reseach Trend of Boron Nitride Nanotube Purification and Surface Modification (질화붕소나노튜브 정제 및 표면처리 연구동향)

  • Lee, Won-Il;Seo, Young-Soo
    • Prospectives of Industrial Chemistry
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    • v.20 no.4
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    • pp.21-33
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    • 2017
  • 질화붕소나노튜브(BNNT: Boron Nitride Nanotube)는 뛰어난 기계적 물성과 전기적 절연성, 높은 열전도도, 열적/화학적 안정성 및 열중성자 흡수 등의 물리화학적 특성으로 인해 다양한 과학기술 분야에서 응용될 수 있는 소재이다. BNNT의 응용성을 증진시키기 위해서 정제 및 표면개질을 통해 BNNT 합성 공정 중 포함되는 불순물의 제거와 용매와 기재에 대한 상용성을 개선해야 할 필요성이 있다. 이에 본 기고에서는 BNNT의 정제 및 표면처리 연구동향에 대해 소개하고자 한다.

Damage Tolerance in Hardly Coated Layer Structure with Modest Elastic Modulus Mismatch

  • Lee, Kee-Sung
    • Journal of Mechanical Science and Technology
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    • v.17 no.11
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    • pp.1638-1649
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    • 2003
  • A study is made on the characterization of damage tolerance by spherical indentation in hardly coated layer structure with modest elastic modulus mismatch. A hard silicon nitride is prepared for the coating material and silicon nitride with 5wt% of boron nitride composites for underlayer. Hot pressing to eliminate the effect of interface delamination during the fracture makes strong interfacial bonding. The elastic modulus mismatch between the layers is not only large enough to suppress the surface crack initiation from the coating layer but sufficiently small to prevent the initiation of radial crack from the interface. The strength degradation of the layer structure after sphere contact indentation does not significantly occur, while the degradation of silicon nitride-boron nitride composite is critical at a high load and high number of contacts.

Synthesis of Cubic Boron Nitride by Al-Mg Solvents

  • Park, Jong-Ku;Park, S.T.;S.K. Singhal;S. J. Cui;K. Y. Eun
    • The Korean Journal of Ceramics
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    • v.3 no.3
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    • pp.187-190
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    • 1997
  • The aluminum-magnesium (Al-Mg) aklloys have been proved to be an effective solvent for synthesis of cubic-phase boron nitride (cBN) from hexagonal-phase boron nitride (hBN) at the conditions of high pressures and high temperatures (HP/HT). Various kinds of hBN powders having different crystallinity have been tested for cBN synthesis with Al-Mg solvents. The conversion ratio from hBN to cBN and the shape of synthesized cBN crystals appeared to be affected strongly by chemical composition and added amount of Al-Mg solvents as well as crystallinity of BN powders. As the magnesium content increased in the Al-Mg solvents, the conversion ratio increased and the size of cBN crystals became larger. The crystal facets developed well in the specimens with solvents having high Mg content. It was observed that a hBNlongrightarrowcBN transformation occurred more easily in the specimens having well crystallized hBN powders. Amorphous BN having much $B_2O_3$ impurity exhibited a low threshold temperature for transformation to cBN, which was attributed to crystallization of amorphous BN to well crystallized hBN prior to transformation into cBN with help of $B_2O_3$.

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Development of Epoxy/Boron Nitride Composites for High Heat Dissipation of Metal Copper Clad Laminate (MCCL) (Metal Copper Clad Laminate (MCCL)의 고방열 특성을 위한 Epoxy/BN 복합체 개발)

  • Choi, Ho-Kyoung;Choi, Jae-Hyun;Choi, Bong-Goo;Yoon, Do-Young;Choi, Joong-So
    • Korean Chemical Engineering Research
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    • v.58 no.1
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    • pp.64-68
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    • 2020
  • In this study, metal copper clad laminate can be prepared using epoxy composite filled with thermally conductive fillers. In order to improve the thermal conductivity of epoxy composites, it is important factor to form conductive networks through appropriate packing of conductive fillers in epoxy composite matrix and to decrease the amount of thermally resistant junctions involving a epoxy composite matrix layer between adjacent filler units. This is because epoxy has a thermal conductivity of only 0.2-0.3W, so in order to maintain high thermal conductivity, thermally conductive fillers are connected to each other, so that the gap between particles can be reduced to reduce thermal resistance. The purpose of this study is to find way to achieve highly thermally conductive in the epoxy composite matrix filled with Al2O3 and Boron Nitride(BN) filler by filler loading and uniform dispersion. As a results, the use of Al2O3/BN hybrid filler in epoxy matrix was found to be effective in increasing thermal conductivity of epoxy composite matrix due to the enhanced connectivity offered by more continuous thermally conductive pathways and uniform dispersion without interfacial voids in epoxy composite matrix. In addition, surface treatmented s-BN improves the filler dispersion and adhesion between the filler and the epoxy matrix, which can significantly decrease the interfacial thermal resistance and increase the thermal conductivity of epoxy composite matrix.

Structural Studies of Thin Film Boron Nitride by X-ray Photoelectron Spectroscopy

  • Kim, Jong-Seong
    • Journal of Sensor Science and Technology
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    • v.5 no.1
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    • pp.51-56
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    • 1996
  • Structural properties of rf sputtered boron nitride films were studied as a function of deposition parameters such as nitrogen pressure, substrate temperature and substrate bias using X-ray photoelectron spectroscopy and Auger electron spectroscopy. Composition and information on chemical bonding of resultant films was determined by XPS. XPS core level spectra showed that ratio of boron to nitrogen varied from 3.11 to 1.45 with respect to partial nitrogen pressure. Curve fitting of XPS spectra revealed three kinds of bonding mechanism of boron in the films. XPS peak positions of both B 1s and N 1s shifted to higher energy with higher nitrogen pressure as well as increase in substrate bias voltage. AES was used to see possible contamination of films by carbon or oxygen as well.

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Nuclear Magnetic Resonance of Carbon Nanotube and Boron Nitride Nanotube (Carbon Nanotube 와 Boron Nitride Nanotube 의 핵자기공명)

  • 정재갑;유권상;남승훈;이규층;이무희;이영희
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.6
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    • pp.22-27
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    • 2004
  • 특성에 대한 많은 연구가 진행되었고, 새로운 나노 소자로서의 가능성을 보여왔다. CNT의 전기적 성질은 직경과 chirality 의 함수로서 금속 혹은 반도체 성질을 주기적으로 가지며, 이론적 연구에 의하면 단일구역의 CNT 는 1/3 이 금속성, 나머지는 밴드갭이 수 ㎷ 로 아주 작고, 나노튜브의 직경에 반비례하는 반도체 성질을 나타낸다.(중략)

High Thermal Conductive Natural Rubber Composites Using Aluminum Nitride and Boron Nitride Hybrid Fillers

  • Chung, June-Young;Lee, Bumhee;Park, In-Kyung;Park, Hyun Ho;Jung, Heon Seob;Park, Joon Chul;Cho, Hyun Chul;Nam, Jae-Do
    • Elastomers and Composites
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    • v.55 no.1
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    • pp.59-66
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    • 2020
  • Herein, we investigated the thermal conductivity and thermal stability of natural rubber composite systems containing hybrid fillers of boron nitride (BN) and aluminum nitride (AlN). In the hybrid system, the bimodal distribution of polygonal AlN and planar BN particles provided excellent filler-packing efficiency and desired energy path for phonon transfer, resulting in high thermal conductivity of 1.29 W/mK, which could not be achieved by single filler composites. Further, polyethylene glycol (PEG) was compounded with a commonly used naphthenic oil, which substantially increased thermal conductivity to 3.51 W/mK with an excellent thermal stability due to facilitated energy transfer across the filler-filler interface. The resulting PEG-incorporated hybrid composite showed a high thermal degradation temperature (T2) of 290℃, a low coefficient of thermal expansion of 26.4 ppm/℃, and a low thermal distortion parameter of 7.53 m/K, which is well over the naphthenic oil compound. Finally, using the Fourier's law of conduction, we suggested a modeling methodology to evaluate the cooling performance in thermal management system.

Theoretical Study of Thiazole Adsorption on the (6,0) zigzag Single-Walled Boron Nitride Nanotube

  • Moradi, Ali Varasteh;Peyghan, Ali Ahmadi;Hashemian, Saeede;Baei, Mohammad T.
    • Bulletin of the Korean Chemical Society
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    • v.33 no.10
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    • pp.3285-3292
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    • 2012
  • The interaction of thiazole drug with (6,0) zigzag single-walled boron nitride nanotube of finite length in gas and solvent phases was studied by means of density functional theory (DFT) calculations. In both phases, the binding energy is negative and presenting characterizes an exothermic process. Also, the binding energy in solvent phase is more than that the gas phase. Binding energy corresponding to adsorption of thiazole on the BNNT model in the gas and solvent phases was calculated to be -0.34 and -0.56 eV, and about 0.04 and 0.06 electrons is transferred from the thiazole to the nanotube in the phases. The significantly changes in binding energies and energy gap values by the thiazole adsorption, shows the high sensitivity of the electronic properties of BNNT towards the adsorption of the thiazole molecule. Frontier molecular orbital theory (FMO) and structural analyses show that the low energy level of LUMO, electron density, and length of the surrounding bonds of adsorbing atoms help to the thiazole adsorption on the nanotube. Decrease in global hardness, energy gap and ionization potential is due to the adsorption of the thiazole, and consequently, in the both phases, stability of the thiazole-attached (6,0) BNNT model is decreased and its reactivity increased. Presence of polar solvent increases the electron donor of the thiazole and the electrophilicity of the complex. This study may provide new insight to the development of functionalized boron nitride nanotubes as drug delivery systems for virtual applications.

Analysis of BNNT(Boron Nitride Nano Tube) synthesis by using Ar/N2/H2 60KW RF ICP plasma in the difference of working pressure and H2 flow rate

  • Cho, I Hyun;Yoo, Hee Il;Kim, Ho Seok;Moon, Se Youn;Cho, Hyun Jin;Kim, Myung Jong
    • Proceedings of the Korean Vacuum Society Conference
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    • 2016.02a
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    • pp.179-179
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    • 2016
  • A radio-frequency (RF) Inductively Coupled Plasma (ICP) torch system was used for boron-nitride nano-tube (BNNT) synthesis. Because of electrodeless plasma generation, no electrode pollution and effective heating transfer during nano-material synthesis can be realized. For stable plasma generation, argon and nitrogen gases were injected with 60 kW grid power in the difference pressure from 200 Torr to 630 Torr. Varying hydrogen gas flow rate from 0 to 20 slpm, the electrical and optical plasma properties were investigated. Through the spectroscopic analysis of atomic argon line, hydrogen line and nitrogen molecular band, we investigated the plasma electron excitation temperature, gas temperature and electron density. Based on the plasma characterization, we performed the synthesis of BNNT by inserting 0.5~1 um hexagonal-boron nitride (h-BN) powder into the plasma. We analysis the structure characterization of BNNT by SEM (Scanning Electron Microscopy) and TEM (Transmission Electron Microscopy), also grasp the ingredient of BNNT by EELS (Electron Energy Loss Spectroscopy) and Raman spectroscopy. We treated bundles of BNNT with the atmospheric pressure plasma, so that we grow the surface morphology in the water attachment of BNNT. We reduce the advancing contact angle to purity bundles of BNNT.

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Improvement of Thermal Conductivity of Poly(dimethyl siloxane) Composites Filled with Boron Nitride and Carbon Nanotubes (보론 나이트라이드와 탄소나노튜브로 충전된 실리콘 고무의 열전도도 향상)

  • Ha, Jin-Uk;Hong, Jinho;Kim, Minjae;Choi, Jin Kyu;Park, Dong Wha;Shim, Sang Eun
    • Polymer(Korea)
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    • v.37 no.6
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    • pp.722-729
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    • 2013
  • In order to enhance the thermal conductivity of poly(dimethyl siloxane) (PDMS), boron nitride (BN) and carbon nanotubes (CNTs) were incorporated as the thermally conductive fillers. The amount of BN was increased from 0 to 100 phr (parts per hundred rubber) and the amount of CNTs was increased from 0 to 4 phr at a fixed amount of the boron nitride (100 phr). The thermal conductivity of the composites increased with an increasing concentration of BN, but the incorporation of CNTs had only a slight effect on the enhancement of thermal conductivity. Unexpectedly, the thermal degradation of the composites was accelerated by the addition of CNTs in 100 phr BN filled PDMS. Activation energy for thermal decomposition of the composites was calculated using the Horowitz-Metzger method. The curing behavior, electrical resistivity, and mechanical properties of PDMS filled with BN and CNTs were investigated.