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습식환원법에서 NaBH<sub>4</sub>환원제를 이용한 Ag분말의 제조
원창환,이혁희,Won Chang-Whan,Lee Huk-Hee 한국분말야금학회 2006 한국분말재료학회지 (KPMI) Vol.13 No.4
Spherical Ag powder was prepared in the system of $AgNO_3\;and\;NaBH_4$ by wet chemical reduction method. The size of Ag powder was increased as the reaction temperature and the concentration of reducing agent was decreased in the constant concentration of dispersion agent. Optimum conditions of producing Ag powder having $1.39{\mu}m$ of D50 was 1M of $AgNO_3$, 0.5M of $NaBH_4$, 1.5g of Gelatine in the room temperature.
양범석,이혁희,원창환,Yang, Beom-Seok,Lee, Huk-Hee,Won, Chang-Whan 한국세라믹학회 2005 한국세라믹학회지 Vol.42 No.7
Conditions for formation of perovskite Pb(Zr$_{0.52}$Ti$_{0.48}$)O$_{3}$ phase by the hydrothermal synthesis are investigated. Pb(Zr$_{0.52}$ Ti$_{0.48}$)O$_{3}$ ceramics were synthesized by hydrothermal process above 180$^{\circ}C$ for 2 h reaction using 5$\~$30 M KOH solution as a mineralizer. Particle size increases in proportion to the mineralizer concentration. As a result of EOX analysis, PZT powders synthesized using 50 M of KOH as a mineralizer were considered as 2.42 mol$\%$ K doped-PZT powders. And 2.42 mol$\%$ K doped-PZT has much higher mechanical quality factor than undoped PZT ceramics. The sintering properties showed 7.987 g/cm$^{3}$ of sintered density and 3$\~$4 $\mu$m of grain size.
자전연소합성법에 의한 TiB<sub>2</sub> 분말의 제조에 있어 반응성에 대한 반응변수의 고찰
신창윤,박영철,이혁희,원창환,Shin, Chang-Yun,Park, Young-Chul,Lee, Huk-Hee,Nersisyan, Hayk,Won, Chang-Whan 한국세라믹학회 2006 한국세라믹학회지 Vol.43 No.1
The preparation of $TiB_2$ by SHS in $B_2O_3-Mg-TiO_2$ system was investigated in this study. In the preparation of $TiB_2$, the effect on reactivity and reaction products of the initial pressure of inert gas in reactor, the content of Mg and $TiO_2$ in mixture was investigated. The minimum initial pressure of inert gas in reactor for SHS reaction in this system was 5atm, and as the pressure increased, the concentration of unreacted Mg decreased and combustion temperature increased. At the initial inert gas pressure in reactor of 50atm, the optimum composition for the preparation of pure $TiB_2$ was $B_2O_3+5Mg+TiO_2$. The $TiB_2$ synthesized in this condition had an irregular shape and the particle size of $1\~3{\mu}m$.
무전해 도금법을 이용한 코어 셸 구조의 Cu-Ag분말 제조
김종완(Jong-Wan Kim),이혁희(Huk-Hee Lee),원창환(Chang-Whan Won) 한국표면공학회 2009 한국표면공학회지 Vol.42 No.1
Cu-Ag powder having Core-Shell structure was prepared from by electroless plating method using agents such as AgNO₃, NH₄OH, Hydroquinone. Ag coated copper powders were analyzed using scanning electron microscopy(SEM) and energy dispersive X-ray spectrometer(EDX). The silver coating layer of copper powder was affected from various reaction conditions such as molar ratio of NH₄OH, AgNO₃, and pulp density. Free silver was generated below 0.1M or 0.3M and above of NH₄OH mole ratio. Silver coating layer thickened as addition of AgNO₃. When the pulp density reached 12% with 0.2M NH₄OH, and 0.15M AgNO₃ at 4℃, silver was homogeneously distributed around the copper particles and free silver particles were not generated.
자전연소합성법을 이용한 비정질 나노 붕소 분말 특성에미치는 첨가제의 영향
주신형,이태혁,조영희,김홍물,이혁희,이종현,Joo, Sin Hyong,Nersisyan, Hayk H.,Lee, Tae Hyuk,Cho, Young Hee,Kim, Hong Moule,Lee, Huk Hee,Lee, Jong Hyeon 한국재료학회 2015 한국재료학회지 Vol.25 No.12
The self-propagating high temperature synthesis approach was applied to synthesize amorphous boron nano-powders in argon atmospheres. For this purpose, we investigated the characteristics of a thermally induced combustion wave in the $B_2O_3+{\alpha}Mg$ system(${\alpha}=1.0-8.0$) in an argon atmospheres. In this study, the exothermic nature of the $B_2O_3-Mg$ reaction was investigated using thermodynamic calculations. Experimental study was conducted based on the calculation data and the SHS products consisting of crystalline boron and other compounds were obtained starting with a different initial molar ratio of Mg. It was found that the $B_2O_3$ and Mg reaction system produced a high combustion temperature with a rapid combustion reaction. In order to regulate the combustion reaction, NaCl, $Na_2B_4O_7$ and $H_3BO_3$ additives were investigated as diluents. In an experimental study, it was found that all diluents effectively stabilized the reaction regime. The final product of the $B_2O_3+{\alpha}Mg$ system with 0.5 mole $Na_2B_4O_7$ was identified to be amorphous boron nano-powders(< 100 nm).