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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.
원창환,정중채,윤기석 대한금속재료학회(대한금속학회) 1999 대한금속·재료학회지 Vol.37 No.2
Fe-Al intermetallic compounds were manufactured by using the field-activated combustion synthesis process. Effects of chemical composition(Fe:Al=1:2, 1:1, 21), compaction pressure(150. 250, 350㎫) and electrical resistance on the reaction were investigated. As the molar ratio of Al, compaction pressure and electric field increased, the combustion temperature and velocity increased. The structure and composition of reaction products were characterized with X-ray, SEM and EDXS to determinethe. As a results, final product was influenced with the composition of reactants, but was not influenced with compression presure.
산화물 (TiO2) 로부터 자전연소반응에 의한 TiC 분말제조
원창환,강복석,천병선 대한금속재료학회(대한금속학회) 1993 대한금속·재료학회지 Vol.31 No.5
The experimental results for the fabrication of TiC powder from TiO₂by self-combustion reaction are summerized as follows; 1) The mole ratio of Mg was the greatest affecting factor in the reaction and the mole ratio of C, particle size of Mg, mixing times affected the reaction as well. 2) MgO and Mg were completely removed by leaching in the 20% HCl solution. 3) The TiC powders had a spherical shape and the particle size was 0.3-0.4 microns with a narrow distribution. 4) Purity of manufactured TiC powder was about 99.925 weight percent.
원창환,손용운,안성권 대한금속재료학회(대한금속학회) 1993 대한금속·재료학회지 Vol.31 No.11
Due to the great hardness, hard nitrides have been extensively used in cutting tools and wear-resistant parts. The nitride also shows excellent high-temperature strength and good corrosion resistance. The purpose of this research is to develop the technology for the synthesis of titanium nitride by the reaction of titanium metal and nitrogen. The titanium nitride(TiN_x) can be manufactured by the several methods. In the present work, bulk TiN_x has been synthesized by the reaction of titanium and nitrogen followed by homogenizing annealing. The homogeneous TiN_(x≥1.0) can be obtained at 1000℃ with the lattice parameter and specific gravity of 0.424㎚ and 5.39g/㎤, respectively similar to that of pure grade TiN.
원창환,성학경 대한금속재료학회(대한금속학회) 1991 대한금속·재료학회지 Vol.29 No.4
The dissolution of silver in NH₄SCN solution containing Fe^(+3) ion and O₂ gas as an oxidant was studied. It was found that the dissolution rate was effected by a pH of solution, concentration of NH₄SCN, O₂ gao and Fe^(+3)ion. And also a transition from diffusion control to chemical reaction control has been noted at a reaction temperature of 60℃.
TiO2/Al/C 계의 연소반응 후 냉각시간이 생성물에 미치는 영향
원창환,고석권,민경호,김형순 대한금속재료학회(대한금속학회) 1998 대한금속·재료학회지 Vol.36 No.12
The effect of the processing factors of self-propagating high temperature synthesis(SHS) was studied on the system of TiO₂/Al/C. The effect of the size of green pellet and initial temperature of reactant on the combustion temperature cooling time and grain size were studied. The prepared Al₂O₃-TiC powders under various cooling time were sintered by pressureless-sintering and hot-pressing to compare their properties. The properties of commercial powder and powder synthesized by SHS were compared each properties. The cooling time can change by the preheating and the size of pellet. The cooling time affected largely grain size cf titanium carbide. However, the grain size of alumina was nor affected by cooling time. The cooling time after complete combustion have to maintain during for a long time. The Al₂O₃-TiC composite of powder prepared by SHS had good properties comparable to commercial powder.
원창환,배장호,이종현,김병범 한국분말야금학회 2004 한국분말재료학회지 (KPMI) Vol.11 No.3
Submicron nickel powders were prepared from aqueous solution under hydrothermal condition. The experimental conditions including the types of protective agents, concentration of the solution and the pH were studied in detail. Starting concentration of nickel ion is a dominant factor affecting particle size. It was shown that the subsequent addition of Poly Vinyl Pyrrolidone(PVP) and Sodium Dodecyle Sulfate(SDS) can help to disperse the nickel powder. X-ray diffraction and SEM were employed to characterize the products.
원창환,조통래,서동희,권호영 대한금속재료학회(대한금속학회) 1988 대한금속·재료학회지 Vol.26 No.2
Chlorination behaviours of tungsten oxide (WO₃) were investigated by means of a thermogravimetric analysis. The rate of chlorination was increased with increasing the mixed ratio of carbon as a reducing agent. the flow. rate of chlorine gas, reaction temperature, and the amount of calcium fluoride as an additive. It was found that experimental results fit well Valensi equation, 1-2/3R-(1-R)^(2/3) = Kt and the rate of chlorination is controlled by a diffusion process, the activation energy of which is 26.0 KJ/mole. Discussion of the chlorination mechanism is also given in the text.