• 한국세라믹학회지
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• 제31권11호
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• pp.1265-1270
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• 1994

Ultra-fine hydroxyapatite powder were synthesized by the hydrothermal reaction at 10 atm, 3 hrs of Ca(OH)2 suspension with (NH4)2HPO4 solution, and were characterized sintering behavior. Sintered bodies of hydroxyapatite powders which synthesized by hydrothermal reaction method has less weight loss, less sintering shrinkage and superior mechanical property, and was more dense than sintered bodies of hydroxyapatite powder which synthesized by wet method. Sintered bodies were hydroxyapatite single phase. When soack in Ringer's solution for 2 weeks, hydroxyapatite powders preserved hydroxyapatite and sintered body absorbed trace of Ca2+ ion with soaked time.

• 한국재료학회지
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• 제34권2호
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• pp.79-84
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• 2024

Thin films of yttria-stabilized zirconia (YSZ) nanoparticles were prepared using a low-temperature deposition and crystallization process involving successive ionic layer adsorption and reaction (SILAR) or SILAR-Air spray Plus (SILAR-A+) methods, coupled with hydrothermal (175 ℃) and furnace (500 ℃) post-annealing. The annealed YSZ films resulted in crystalline products, and their phases of monoclinic, tetragonal, and cubic were categorized through X-ray diffraction analysis. The morphologies of the as-prepared films, fabricated by SILAR and SILAR-A+ processes, including hydrothermal dehydration and annealing, were characterized by the degree of surface cracking using scanning electron microscopy images. Additionally, the thicknesses of the YSZ thin films were compared by removing diffusion layers such as spectator anions and water accumulated during the air spray plus process. Crack-free YSZ thin films were successfully fabricated on glass substrates using the SILAR-A+ method, followed by hydrothermal and furnace annealing, making them suitable for application in solid oxide fuel cells.

• 한국세라믹학회지
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• 제46권3호
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• pp.288-294
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• 2009

The platelet AlO(OH) nano colloids were prepared by hydrothermal reaction of the $\gamma-Al_2O_3$ obtained with dehydration of $\gamma$-AlO(OH) and dilute $CH_3COOH$ solution. In hydrothermal reaction process, reversible reaction was accompanied between $\gamma-Al_2O_3$ and AlO(OH), and hydrothermal reaction temperature, hydrothermal reaction time and $CH_3COOH$ concentration had an effect on the crystal structure, surface chemical property, surface area, pore characteristics and crystal morphology of the AlO(OH) nano colloid particles. In this study, it was investigated to the hydrothermal reaction condition of the AlO(OH) nano colloid for using catalyst support, heat resisting agent, adsorbents, binder, polishing agent and coating agent. The crystal structure, surface area, pore volume and pore size of the platelet AlO(OH) nano colloids were investigated by XRD, TEM, TG/DTA, FT-IR and $N_2$ BET method in liquid nitrogen temperature.

• 한국결정성장학회지
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• 제11권5호
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• pp.185-189
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• 2001

비정질 인산알루미늄 분말은 화학양론조성비의 $Al_2(SO_4)_3$와 $H_3PO_4$혼합물을 NaOH 또는 KOH 용액을 이용하여 중화 반응시킨 뒤 이를 수열침전법에 의해 단일상으로 얻을 수 있었으며, 합성조건은 다음과 같다. 즉, 출발원료; $Al_2(SO_4)_3$와 $H_3PO_4$, 중화반응의 pH범위; 5.6~6.0, 수열반응의 온도범위; 170~$180^{\circ}C$, 수열반응의 시간범위; 4~5시간이었다. 이와 같은 조건하에서 얻어진 생성물은 0.1~0.3$\mu\textrm{m}$ 크기의 비정질 인산알루미늄 미립자였으며 그리고 미국약전에 따라 실험한 결과 모두 적합하였다.

• 한국결정성장학회지
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• 제17권4호
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• pp.172-178
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• 2007

수평회전식 수열법에 의해 운모 분말을 합성하였다. 수열조건은 출발원료로 $K_2O,\;Al(OH)_3$ 그리고 $SiO_2$의 비는 1 : 3 : 3mol%로 하고 수열용매로 8mol%의 KOH를 함께 추가하여 $260^{\circ}C$에서 72시간 동안 반응시켰다. 합성한 분말은 수직형 수열처리법에 의한 은나노 코팅 운모 제조를 위해 사용하였다. 은나노 코팅의 처리를 위한 수열조건은 출발원료로 합성한 분말로 하고, 수열용매로 $0.5{\ell}$ 3차 증류수, 그리고 1,000ppm의 은나노 졸을 코팅원료로 사용하여 $160{\sim}260^{\circ}C$ 범위에서 72시간 동안 반응시켰다. 처리 후 결정구조, 은나노 코팅 여부 및 코팅된 운모의 특성은 XRD, SEM, TEH-EDX 및 shake plask법을 통해 분석하였다.

• 상하수도학회지
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• 제29권1호
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• pp.57-63
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• 2015

Recently, Korea's municipal wastewater treatment plants generated amount of wastewater sludge per day. However, ocean dumping of sewage sludge has been prohibited since 2012 by the London dumping convention and protocol and thus removal or treatment of wastewater sludge from field sites is an important issue on the ground site. The hydrothermal carbonization is one of attractive thermo-chemical method to upgrade sewage sludge to produce solid fuel with benefit method from the use of no chemical catalytic. Hydrothermal carbonization improved that the upgrading fuel properties and increased materials and energy recovery, which is conducted at temperatures ranging from 200 to $350^{\circ}C$ with a reaction time of 30 min. Hydrothermal carbonization increased the heating value though the increase of the carbon and fixed carbon content of solid fuel due to dehydration and decarboxylation reaction. Therefore, after the hydrothermal carbonization, the H/C and O/C ratios decreased because of the chemical conversion. Energy retention efficiency suggest that the optimum temperature of hydrothermal carbonization to produce more energy-rich solid fuel is approximately $200^{\circ}C$.

• 한국전기전자재료학회논문지
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• 제28권9호
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• pp.561-564
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• 2015

Nano-size $BaTiO_3$ powder was synthesized by relatively simple hydrothermal reaction method. Finely dispersed Ti hydroxide precursor was first precipitated using $Ti(SO_4)_2$ and NaOH solution by applying ultrasonic power and washed thoroughly to remove $SO_4{^{2-}}$ and $Na^+$ ion. Then hydrothermal reaction was done at $160^{\circ}C$ for 6 hrs using solution prepared by washed Ti hydroxide precursor slurry and $Ba(OH)_2{\cdot}8H_2O$ with Ti:Ba mole ratio of 1:1. 200 ~ 500 nm size and uniform size distributed $BaTiO_3$ powder was synthesized by relatively low temperature and simple process.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.420-421
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• 2005

$LiMnPO_4$ particle were prepare by a hydrothermal reaction. The particles prepared by adding polyethylene glycol(PEG) and carbon to the starting reaction solution were fine crystalline in the range of 200-300nm. The discharge capacity of the sample as a lithium secondary battery was $25mAhg^{-1}$ at $0.04mAcm^{-2}$, larger than that of the sample prepared by the hydrothermal method without PEG and carbon.

• International Journal of Concrete Structures and Materials
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• 제10권1호
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• pp.15-28
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• 2016

With the aim to reduce the atmospheric $CO_2$, utilization of the carbonated lime produced from the aqueous carbonation reaction for the synthesis of a cementitious material would be a promising approach. The present investigation deals with the aqueous carbonation of slaked lime, followed by hydrothermal synthesis of a cementitious material utilizing the carbonated lime, silica fume, and hydrated alumina. In this study, the aqueous carbonation reaction was performed under four different conditions. The TGA, FESEM, and XRD analysis of the carbonated product obtained from the four different reaction conditions was performed to evaluate the efficacy of the reaction conditions used for the production of the carbonated lime. Additionally, the performance of the cementitious material was verified analyzing the physical characteristics, mechanical property and setting time. Based on the results, it is demonstrated that the material produced by the hydrothermal method possesses the cementing ability. Additionally, it is revealed that the mortar prepared using the alternative cementitious material yields $33.8{\pm}1.3MPa$ compressive strength. Finally, a plausible reaction scheme has been proposed to explain the overall performances of the aqueous carbonation as well as the hydrothermal synthesis of the cementitious material.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1985년도 하계학술회의논문집
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• pp.191-193
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• 1985

Reaction temperature md piezoelectric properties of Pb(Mn1/3 Sb2/3)0.08 Ti0.495 Zr0.425 $O_3$ ceramics by hydrothermal synthesis method have been investigated. Sintering density and dielectric constant of sample increased with increasing of hydrothermal reaction temperature, while decreased rapidly above $240^{\circ}C$. Electromechanical coupling factor kp was almost constant at the reaction temperature $160^{\circ}-240^{\circ}C$.