• 한국전기전자재료학회논문지
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• 제33권5호
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• pp.373-379
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• 2020

In this study, TiN-coated cBN (cubic-structure boron nitride) powders were successfully synthesized by a sol-gel method using titanium (IV) isopropoxide (TTIP) and by controlling the heat treatment conditions. After the sol-gel process, amorphous nano-sized TiO_x was uniformly coated on the surface of cBN powder particles. The obtained TiO_x-coated cBN powders were heated at 1,000~1,300℃ for 1 or 6 h in a flow of 95%N₂-5%H₂ mixed gas. With increasing temperature, the chemical composition of the TiO_x coating layer changed in the order of TiO₂→Ti₆O₁₁→Ti₄O₇→TiN due to reduction of the Ti ions. The TiN coating layer was observable in the samples heated at 1,200℃ and appeared as the main phase in the sample heated at 1,300℃. The resulting thickness of the TiN coating layer of the sample heated at 1,300℃ was approximately 45~50 nm.

• 한국안광학회지
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• 제3권1호
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• pp.217-222
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• 1998

$SiO_2-TiO_2-AgO$ 코팅박막을 졸-겔법으로 현미경용 슬라이드 유리판과 씰리콘 기판에 제조하였다. 이 박막의 열처리온도는 $500^{\circ}C$가 적절하였으며 5회 반복코팅한 박막의 두께는 310nm였다. AgO가 10mol% 첨가된 박막의 표면은 균일한 구조를 보였으나 첨가량이 많아질수록 박막의 표면에 pin hole과 AgO의 석출에 기인한 cluster를 보였다. 열처리온도의 증가에 따라 IR흡수의 정도가 점차 감소하였고, AgO 첨가량의 증가에 따라 반사율은 점차 감소하였으며 색상은 light yellow에서 무채색 쪽으로 점차 전이하였다.

• Progress in Superconductivity
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• 제13권2호
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• pp.127-132
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• 2011

Many research groups have been manufacturing coated conductor by various processes such as PLD, MOD, and MOCVD, but the methods with production cost suitable for wide and massive application of coated conductor did not develop yet. Spray pyrolysis method adopting ultrasonic atomization was tried as one of the possible option. GdBCO precursor films have been deposited on IBAD substrate by spray pyrolysis method at low temperature and converted to GdBCO by post heat treatment. Ultrasonic atomization was used to generate fine droplets from precursor solution of Gd, Ba, and Cu nitrate dissolved in water. Primary GdBCO films were deposited at $500^{\circ}C$ and oxygen partial pressure of 1 torr. After that, the films were converted at various temperatures and low oxygen partial pressures. C-Axis oriented films were obtained IBAD substrates at conversion temperature of around $870^{\circ}C$ and oxygen partial pressures of 500 mtorr ~ 1 torr in a vacuum. Thick c-axis epitaxial film with the thickness of 0.4 ~ 0.5 ${\mu}m$ was obtained on IBAD substrate. C-axis epitaxial GdBCO films were successfully prepared by ex-situ methods using nitrate precursors on IBAD metal substrate. Converted GdBCO films have very dense microstructures with good grain connectivity. EDS composition analysis of the film showed a number of Cu-rich phase in surface. The precursor solution having high copper concent with the composition of Gd : Ba : Cu = 1 : 2 : 4 showed the better grain connectivity and electrical conductivity.

• 한국가구학회지
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• 제19권6호
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• pp.475-486
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• 2008

In this study, fire-retardant chemicals were melt with mixed composition ratios of dibasic ammonium phosphate and each half of boric acid and borax in hot water, in which hammer-milled chips were immersed to increase swelling of waste particleboards. Also, fire-retardant treated particles from sawn lumber chip and recycled particleboard chip were composed in ratio of 70:30 in core layer to improve boards' properties. Retention ratio of fire-retardant chemicals for the particles for face layer was high due to high specific surface area, and that of sawn lumber chips was somewhat higher than that of recycled particleboard chips. The mixture of particles from sawn lumber chips and recycled PB of 70:30 in weight ratio exceeded bending strength of 100 $kgf/cm^2$. It seemed that the relatively greater portions of dibasic ammonium phosphate affected adversely to dimensional stability, however fire-retardants treatment resulted in distinct effect lowering formaldehyde emission such as $E_0$ type(0.5mg/$\ell$ or less) in KS F 3104. In fire-retardancy, the recycled boards with a mixed ratio of dibasic ammonium phosphate to boric acid borax(50:50 mixture) of 70% to 30% in weight satisfied fire-retardancy 3rd grade in KS F 2271, and also this composition from cone calorimeter test met same standard grade figuring total heat release of 4.6MJ/$m^2$.

• 한국분말재료학회지
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• 제16권3호
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• pp.196-202
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• 2009

A visible-light photoactive $TiO_{2-x}N_x$ photocatalyst was synthesized successfully by means of cogrinding of anatase-$TiO_2(a-TiO_2)$ in $NH_3$ ambient, followed by heat-treatment at $200^{\circ}C$ in air environment. In general, it is well known that the grinding-operation induces phase transformation of a-$TiO_2$ to rutile $TiO_2$. This study investigates the influence of the amount of $NH_3$ gas on the phase transformation rate of a-$TiO_2$ and enhancement of visible-light photocatalytic activity, and also examines the relation between the photocatalytic activity and the period of grinding time. The phase transformation rate of a-$TiO_2$ to rutile is retarded with the amount of NH3 injected. And the visible-light photocatalytic activity of samples, was more closely related to the period of grinding time than $NH_3$ amount injected, which means that the doping amount of nitrogen into $TiO_2$ more effective to mechanical energy than $NH_3$ amount injected. XRD, XPS, FT-IR, UV-vis, Specific surface area (SSA), NOx decomposition techniques are employed to verify above results more clearly.

• 한국분말재료학회지
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• 제27권2호
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• pp.139-145
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• 2020

The powder manufacturing process using the gas atomizer process is easy for mass production, has a fine powder particle size, and has excellent mechanical properties compared to the existing casting process, so it can be applied to various industries such as automobiles, electronic devices, aviation, and 3D printers. In this study, a modified A4032-xSn (x = 0, 1, 3, 5, and 10 wt.%) alloy with low melting point properties is investigated. After maintaining an argon (Ar) gas atmosphere, the main crucible is tilted; containing molten metal at 1,000℃ by melting the master alloy at a high frequency, and Ar gas is sprayed at 10 bar gas pressure after the molten metal inflow to the tundish crucible, which is maintained at 800℃. The manufactured powder is measured using a particle size analyzer, and FESEM is used to observe the shape and surface of the alloy powder. DSC is performed to investigate the change in shape, according to the melting point and temperature change. The microstructure of added tin (Sn) was observed by heat treatment at 575℃ for 10 min. As the content of Sn increased, the volume fraction increased to 1.1, 3.1, 6.4, and 10.9%.

• 대한환경공학회지
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• 제37권6호
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• pp.357-362
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• 2015

새로운 형태의 $TiO_2$가 합성된 코코넛 껍질 분말 복합체를 제조하기 위해 솔-젤 합성법과 열처리를 사용하였고, 제조된 TCSPC는 MB를 대상으로 제거효율을 평가하였다. TCSPC를 제조하기 위한 최적의 조건은 반응표면분석법의 중심합성설계법을 사용하여 조사하였다. 소성온도가 $400^{\circ}C$에서 $600^{\circ}C$ 증가함에 따라 BET 비표면적은 $254m^2/g$에서 $398m^2/g$로 증가하고 기공용적, 기공률 또한 증가하며, 그 이유는 소성공정 시 발생한 열분해(pyrolysis)에 의해 코코넛 껍질 분말이 가지고 있는 헤미셀룰로우스, 셀룰로우스, 그리고 리그닌과 같은 물질들의 polymerization 반응 때문인 것으로 판단된다. 코코넛 껍질 분말의 양이 10 g에서 20 g으로 증가 할수록 BET 비표면적은 $303m^2/g$에서 $398m^2/g$로 증가하였으며, 30 g으로 증가 시에는 BET 비표면적은 $345m^2/g$으로 감소하는 경향을 나타내었다. Response optimization을 사용하여 얻은 최적의 합성조건은 소성온도 $642^{\circ}C$, 코코넛 껍질 분말 주입량이 22.7 g으로 나타났다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.241.1-241.1
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• 2011

Numerous possible applications for $ZrO_2$ nanotubes exist such as for catalyst support structures, for sensing or for applications as a solid state electrolyte. Especially, because of a large specific surface area, high efficiency for solid oxide fuel cell (SOFC) application at low temperature can be expected for nanotublar structures in even small size. A zirconium precursor, Tetrakis (ethylmethylamino) zirconium, TEMAZr and $H_2O$ oxidant were used to deposit$ZrO_2$ thin films on an anodized aluminum oxide (AAO) templates having sub-100nm cylindrical pores by atomic layer deposition (ALD) in the temperature range of 150~250$^{\circ}C$. The crystalline structures of as-prepared and post-annealed $ZrO_2$ nanotubes were characterized by x-ray diffraction and high-resolution transmission electron microscopy. The as-prepared samples at $150^{\circ}C$ and $200^{\circ}C$ were showed amorphous, whereas a mixed phase of tetragonal, monoclinic and amorphous polymorph was observed at $250^{\circ}C$. In the bulk, zirconia remains monoclinic phase up to $1,175^{\circ}C$, however, $ZrO_2$ nanotubes were showed tetragonal phase upon post thermal treatments merely at $400^{\circ}C$. This trend may be indicative of high-curvature surfaces of nanotubes and thereby the presence of intrinsic compressive strain. The amount of amorphous structures in the mixed phase as well as as-grown $ZrO_2$ nanotubes were also gradually decreased by subsequent heat treatment.

• 한국진공학회지
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• 제11권4호
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• pp.194-200
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• 2002

MOCVD(metal-organic chemical vapor deposition) Cu 박막을 여러 조건에서 열처리를 행하여 그 전기적 특성과 미세구조의 변화를 통해 적절한 열처리 조건을 찾고 그 효과를 조사하였다. Ar 1 torr, $400^{\circ}C$에서 열처리를 거친 Cu 박막의 비저항이 1.98 $\mu$Ω.cm로 가장 낮게 나타났으며, 결정성의 경우도 $I_{(111)}/I_{(200)}$의 비가 2.03에서 3.11로 열 처리를 거치지 않았을 경우와 비교해서 약 50% 정도 향상된 값을 나타내었다. 열처리 후의electromigration(EM) 테스트에서는 Ar 1 torr, $400^{\circ}C$에서 열처리를 거친 배선이 EM에 대한 가장 높은 저항성을 보였다. 이것은 열처리 후 낮은 비저항, (111) 결정면의 성장, 그리고 표면 거칠기의 감소에서 기인한 것이다.

• 한국결정성장학회지
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• 제13권3호
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• pp.139-144
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• 2003

유기용매로서 에탄올을 함유한 염화니켈 수용액으로부터 니켈 미분말을 제조하고 이들의 산화특성을 검토하였다. 에탄올을 함유한 염화니켈 수용액에서 히드라진의 환원반응은 반응온도에 크게 의존하였다. 히드라진에 의한 환원반응시간은 반응온도가 증가함에 따라 감소하였다. 반응온도를 제어함으로써 입경이 0.1 $\mu\textrm{m}$-1.0 $\mu\textrm{m}$ 범위를 갖는 구형 분말을 얻을 수 있었다. 또한, 반응온도가 증가함에 따라 입경은 다소 증가하였고 조대한 입자들의 존재로 인하여 넓은 입도 분포를 나타내었다. $60^{\circ}C$에서 합성된 니켈 분말의 평균 입경과 비표면적은 각각 0.3 $\mu\textrm{m}$와 31.8 $m^2$/g이었다. $300^{\circ}C$에서 니켈 분말의 중량감소는 $Ni(OH)_2$의 분해반응에 기인한 것이다. $200^{\circ}C$ 공기중에서 가열처리한 경우 내산화성은 합성 분말보다 현저하였다