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에어로졸 반응기를 이용한 기상에서의 Polyurea 미립자의 제조
김성익,김선근 ( Sung Ik Kim,Sun Geon Kim ) 한국화학공학회 1993 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.31 No.6
Spherical polymer particles with narrow size distribution have been prepared by aerosol-phase polymerization. The polyurea particles were prepared by the reaction of TDI(toluene-2,4-diisocyanate) or HDI(hexamethylene diisocyanate) droplets with EDA(ethylene diamine) vapor. The use of seed(NaCl) nuclei helped the polymer particles smaller in size and made the size distribution of the particles narrower. The particle size increased substantially with boiler temperature and decreased slightly with increasing the carrier gas flow rate. Increase in reboiler temperature improved the monodispersity of the particle size. Sphericity and surface smoothness of the particles were improved by decreasing particle size and controlling the reaction rates. The coating of TiO₂ on the surface of the prepared polymer particles was carried out by condensing Ti(Oet)₄ on the particle surface and subsequently reacting the liquid film with water vapor. The reaction system was also applied to prepare polyamide particles successfully.
양정선,오의경,김선근 ( Jung Sun Yang,Eui Kyung Oh,Sun Geon Kim ) 한국화학공학회 1996 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.34 No.5
Characteristics of sorbents for flue gas desulfurization has been investigated in sand-bed reactor. SO₂ removal efficiency in gas phase was compared for the various sorbents, process variables and additives. The results have been discussed by observing and analyzing the sorbent particles before and after sulfation with SEM, EDX, XRD, TGA and BET. The SO₂ removal efficiency of the sorbents was affected by their hygroscopicity, surface area and pore-structure change during the reaction. In case of Ca(OH)₂ pore plugging was observed, and humidity of the gas and addition of the additives were directly related with the pore plugging.
기상반응에 의한 초미립 무기분말 제조시 입자성장 모델연구 - 초미립 철분말 제조에의 응용 -
박균영,오의경,김선근,장희동 ( Kyun Young Park,Eui Kyung Oh,Sun Geon Kim,Hee Dong Jang ) 한국화학공학회 1996 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.34 No.4
Presented is a model for the prediction of the particle size distribution of inorganic powders made by the gasphase reaction. The assumption used in previous models that a monomer forms a nucleus is eliminated; the model incorporates the determination of the number of monomers required to form a nucleus and the nucleation rate based on the classical theory. The present model was applied to a manufacture of ultrafine iron powders by hydrogen reduction of FeCl₂ vapor. The average particle size of the iron powder predicted by the model was one half to two thirds of the experimental value. For a reaction temperature of 900℃, the model could fit the experimental diameter by using the surface tension of iron 1.283 times as high as that in the literature. The model prediction agrees well with experimental observation in the trend of particle size increasing with the feed rate of FeCl₂. The model, however, showed a deviation from experimental observations on the effects of the reaction temperature and of the preheating temperature on the particle size. Further investigation needs to be followed to correct the model.
박희재,오의경,김선근,여태환 ( Hee Jae Park,Eui Kyeong Oh,Sun Geon Kim,Tae Whan Yeu ) 한국화학공학회 1994 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.32 No.3
The activated surface of 60-㎛ alumina powders was chemically plated to form nickel-phosphorous films by slow addition of the reactants-nickel salt and sodium hypophosphite solutions-. This semibatch type of reaction mode could control the plating rate easily and guarantee the adhesion of the film to the powder surface and the suppression of the undesirable particle production in broader range of the plating conditions. The semibatch type also made it possible to prepare the plated powders with better chemical, electrical and magnetic properties. The pH of the reacting system, the molar ratio and the input rate of the reactants had great effects on the rate of plating, the electrical resistivity, the chemical composition, the adhesion and the magnetic property of the film.
얼음 미립사 제트에 의한 표면 세척 ( 1 ) - 에어러졸의 제조와 저압 Impaction -
주동운,정종헌,김선근 ( Dong Un Ju,Jong Hwun Chung,Sun Geon Kim ) 한국화학공학회 1996 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.34 No.3
Low-pressure impaction of fine ice particles has been experimentally investigated. First, aerosols consisting of fine water droplets were prepared by two-fluid and ultrasonic nebulizations, and water-vapor condensation. The average size and total number concentration of the droplets were controlled in wide range by the preparation methods and the process variables set for each preparation. The aerosols were next cooled by heat transfer in liquid nitrogen bath and the droplets were solidified. Finally, high-velocity jet of the ice particles was produced by expansion through a nozzle into low-pressure chamber where a substrate is impacted by them. The strength of impaction on the substrate varies with the chamber pressure, impaction angle, and nozzle-to-substrate distance as well as the size and number concentration of the ice particles.