• 한국분말재료학회지
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• 제27권6호
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• pp.503-508
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• 2020

The mechanical properties and microstructures of hexagonal boron nitride (h-BN)-reinforced cement composites are experimentally studied for three and seven curing days. Various sizes (5, 10, and 18 ㎛) and concentrations (0.1%, 0.25%, 0.5%, and 1.0%) of h-BN are dispersed by the tip ultrasonication method in water and incorporated into the cement composite. The compressive strength of the h-BN reinforced cements increases by 40.9%, when 0.5 wt% of 18 ㎛-sized h-BN is added. However, the compressive strength decreases when the 1.0 wt% cement composite is added, owing to the aggregation of the h-BNs in the cement composite. The microstructural characterization of the h-BN-reinforced cement composite indicates that the h-BNs act as bridges connecting the cracks, resulting in improved mechanical properties for the reinforced cement composite.

• 한국세라믹학회지
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• 제34권3호
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• pp.249-256
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• 1997

100-500KHz범위의 주파수전원을 인가하여 발생한 플라즈마를 이용하여 질화붕소(boron nitride)막의 합성시 육방정상(hexagonal phase)과 입방정상(cubic phase)의 생성거동을 관찰하였다. BCl3와 NH3를 붕소와 질소의 공급기체로 선택하였고 Ar과 수소를 carrier기체로 사용하였다. 합성변수로는 플라즈마전원의 전압, 기판의 bias, 합성압력, 기체의 조성, 기판의 온도이었는데, 합성된 박막은 FT-IR결과로부터 육방정과 입방정의 혼합상으로 나타났고, 각 상의 분률은 변수의 크기에 의존하였다. TEM분석결과 육방정으로만 구성된 박막은 비정질상으로 이루어졌으며, 입방정과 육방정의 혼합상의 경우는 비정질기지상에 수십 nanometer크기의 입방정입자가 분산된 구조를 하고 있었다.

• 대한금속재료학회지
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• 제56권12호
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• pp.915-920
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• 2018

With the development of modern microelectronics technologies, the power density of electronic devices is rapidly increasing, due to the miniaturization or integration of device elements which operate at high frequency, high power conditions. Resulting thermal problems are known to cause power leakage, device failure and deteriorated performance. To relieve heat accumulation at the interface between chips and heat sinks, thermal interface materials (TIMs) must provide efficient heat transport in the through-plane direction. We report on the enhanced thermal conduction of $Al_2O_3-based$ polymer composites, fabricated by the surface wetting and texturing of thermally conductive hexagonal boron nitride(h-BN) nanoplatelets with large anisotropy in morphology and physical properties. The thermally conductive polymer composites were prepared with hybrid fillers of $Al_2O_3$ macro beads and surface modified h-BN nanoplatelets. Hexagonal boron nitride (h-BN) has high thermal conductivity and is one of the most suitable materials for thermally conductive polymer composites, which protect electronic devices by efficient heat dissipation. In this study, we synthesized hexagonal boron nitride nanoparticles by the pyrolysis of cost effective precursors, boric acid and melamine. Through pyrolysis at $900^{\circ}C$ and subsequent annealing at $1500^{\circ}C$, hexagonal boron nitride nanoparticles with diameters of ca. 50nm were synthesized. We demonstrate that the addition of a small amount of calcium fluoride ($CaF_2$) during the preparation of the melamine borate adduct significantly enhanced the crystallinity of the h-BN and assisted the growth of nanoplatelets up to 100nm in diameters. The addition of a small amount of h-BN enhanced the thermal conductivity of the $Al_2O_3-based$ polymer composites, from 1.45W/mK to 2.33 W/mK.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.591-591
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• 2013

Fully and partially grown hexagonal boron nitride (h-BN) on Cu foil, synthesized by chemical vapor deposition method, was studied using Raman and SEM measurements. Fully and partially grown samples were successfully made from borane-ammonia complex to controlling pressure and growth time. The fully grown h-BN and partially grown h-BN exhibits a ~1,370 $cm^{-1}$ B-N vibrational mode ($E_{2g}$) Especially, well-aligned triangular h-BN monolayer was observed on some domain of Cu foil using SEM measurements.

• 한국세라믹학회지
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• 제46권1호
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• pp.53-57
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• 2009

The h-BN powder was synthesized by amorphous $B_2O_3$ and activated carbon at $1550^{\circ}C$ in nitrogen atmosphere, whose properties were examined according to $MgB_6$ addition. Amount of $MgB_6$ addition was varied in the range of $0{\sim}$10\;wt% of the initial mixture. It was observed that $MgB_6$ addition led to an increase in the amount and the grain size of h-BN and decrease in the amount of $B_4C$ forming. When $MgB_6$ added 5 wt%, the amount and crystallinity of h-BN increased as the holding time at the synthesis temperature was prolonged. It was also confirmed that the regularity of three-dimensional ordering of h-BN increases.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.382-382
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• 2011

이차원 결정인 그래핀(graphene)은 전하도핑(charge doping)과 기계적 변형에 민감하기 때문에 기판의 물리 및 화학적 구조 및 특성에 따라 그래핀의 물성이 크게 영향을 받는다고 알려져 있다. 특히 널리 사용되고 있는 산화실리콘($SiO_2$/Si) 기판에 존재하는 나노미터 크기의 굴곡과 전하 트랩(charge trap)은 전하 이동도 및 화학적 안정성 등의 면에서 그래핀 고유의 뛰어난 물성을 제한하는 것으로 알려져 있다. 본 연구에서는 비정질 산화실리콘 기판을 대조군으로 삼아 편평도가 높은 결정성 h-BN (hexagonal boron nitride) 기판이 그래핀에 미치는 영향을 관찰하였다. 화학기상증착법(chemical vapor deposition 또는 CVD)으로 성장시킨 그래핀을 각 기판에 전사시킨 후 라만 분광법을 통해 전하 도핑 및 기계적 변형 정도를 측정하였다. h-BN 위에서는 외부 환경에서 기인하는 전하 도핑 정도가 산화실리콘 기판보다 적게 관찰되었다. 또한 h-BN 위에 고착된 그래핀 시료에서는 기판-그래핀 상호작용에서 기인하는 것으로 보이는 새로운 라만 분광 특성이 관찰되었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.192-192
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• 2012

The next generation electronics need to not only be smaller but also be more flexible. To meet such demands, electronic devices using two dimensional (2D) atomic crystals like graphene, hexagonal boron nitride (h-BN), molybdenum disulfate ($MoS_2$) and organic thin film have been studied intensely. In this talk, I will demonstrate the $MoS_2$ field effect transistor (FET) toward performance enhancement by insulating h-BN substrate.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.344.2-344.2
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• 2016

Fully and partially grown hexagonal boron nitride (h-BN) on Cu foil, synthesized by chemical vapor deposition method, was studied using Raman and SEM measurements. Fully and partially grown samples were successfully made from borane-ammonia complex to controlling pressure and growth time. The fully grown h-BN and partially grown h-BN exhibits a ~ 1370 cm-1 B-N vibrational mode (E2g). Especially, well-aligned triangular h-BN monolayer was observed on some domain of Cu foil using SEM measurements.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2013년도 춘계학술대회 논문집
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• pp.170-170
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• 2013

We present a novel etching technique for 2-dimentional (2-D) hexagonal boron nitride (h-BN) by using capacitively coupled plasma (CCP) of oxygen combined with a post-treatment by de-ionized (DI) water. Oxygen CCP etching process for h-BN has been systematically studied. It is found that a passivation layer was generated to obstruct further etching while it can be easily and radically removed by DI water. An essential cleaning effect also has been observed in the etching process, organic residues are successfully removed and the surface roughness has much decreased. Considering h-BN is the most important 2-D dielectric material and its potential application for graphene to silicon-based electronic devices, such an etching method can be widely used to control the 2-D h-BN thickness and improve the surface quality.

• Corrosion Science and Technology
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• 제21권1호
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• pp.41-52
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• 2022

Herein, we report polyvinyl butyral composites coatings containing various loadings of 72-h bath sonicated hexagonal boron nitride particles (5 ㎛) to enhance barrier properties of coatings. Barrier properties of coatings were determined in 3.5 wt% NaCl after different time periods of immersion via electrochemical techniques such as open circuit potential, electrochemical impedance spectroscopy, and potentiodynamic polarization test. Coatings containing sonicated hexagonal boron particles exhibited improved corrosion resistance for longer periods of immersion compared to neat coating. We also discussed effects of hexagonal boron nitride on healing properties of polyvinyl butyral. Coatings containing 1.0 wt% loading of sonicated hexagonal boron nitride showed improved long-term barrier properties than coatings with other compositions. The presence of hexagonal boron nitride also affected the healing properties of polyvinyl butyral coatings besides their barrier properties. Such improved barrier properties of composites coatings were attributed to the high aspect ratio, plate-like shape, and electrically insulated nature of the filler.