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필터 팽창 액적 발생 장치를 이용한 미세한 silver 입자의 형상 및 크기
강윤찬,박승빈 ( Yun Chan Kang,Seung Bin Park ) 한국화학공학회 1996 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.34 No.2
Silver particles with submicron-size were prepared from silver nitrate solutions at various conditions by using the filter expansion aerosol generator(FEAG), and the size and morphology of particles were compared with those of particles prepared by ultrasonic spray pyrolysis. XRD and TGA analysis showed that pure silver particles were formed in 0.02 sec of residence time above 700℃ with air and nitrogen as carrier gas. As the precursor concentration increased from 0.004 to 0.5 ㏖/ℓ, the mean particles size increased from 0.22 to 0.72㎛ for FEAG process. Above 700℃, silver particles with spherical and homogeneous morphology were produced, and larger size and broader size distribution particles were formed at higher reactor temperatures. The mean size of silver particles prepared from 0.5 ㏖/ℓ precursor solution by the FEAG process was 0.72㎛, which is smaller than 1.1㎛ particles formed by ultrasonic spray pyrolysis. This result is ascribed to the finer droplets size in the FEAG process.
액적 분급 장치를 적용한 분무열분해 공정으로부터 합성된 실리카 분말의 특성
강윤찬,주서희,구혜영,강희상,박승빈,Kang, Yun-Chan,Ju, Seo-Hee,Koo, Hye-Young,Kang, Hee-Sang,Park, Seung-Bin 한국재료학회 2006 한국재료학회지 Vol.16 No.10
Silica powders with spherical shape and narrow size distribution were prepared by large-scale ultrasonic spray pyrolysis applying the droplet classification apparatus. On the other hand, silica powders prepared by large-scale ultrasonic spray pyrolysis without droplet classification apparatus had broad size distribution. Droplet classification apparatus used in this paper applied the principles of cyclone and dispersion plate with small holes. The droplets formed from the ultrasonic spray generator applying the droplet classification apparatus had narrow size distribution. The droplets with fine and large sizes were eliminated by droplet classification apparatus. The optimum flow rate of the carrier gas and diameter of the hole of the dispersion plate were studied to reduce the size distribution of the silica powders prepared by large-scale ultrasonic spray pyrolysis. The size distribution of the silica powders prepared by large-scale ultrasonic spray pyrolysis at the optimum preparation conditions was 0.76.
산화칼슘의 저온수화에 의한 고농도의 수산화칼슘 현탁액으로부터 입방형 탄산칼슘 입자의 제조
강윤찬(Yun Chan Kang),박승빈(Seung Bin Park) 한국화학공학회 1997 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.35 No.6
Cubic-type calcium carbonate particles were prepared from high concentration suspensions of calcium hydroxide by introducing low temperature hydration process of calcium oxide. Spindle-type calcium carbonate particles were obtained at higher concentrations than 50 g/ℓ from the calcium hydroxide suspension obtained at high temperature hydration. From the calcium hydroxide suspensions obtained at low hydration temperatures. however. cubic-type calcium carbonate particles were prepared even at high concentration of 150 g/ℓ of calcium hydroxide. The maximum temperature for the formation of cubic-type calcium carbonate particles from high suspension concentrations was 30℃. The mean size of cubic-type calcium carbonate particles increased with increasing the suspension concentrations when the hydration temperature was low.
분체공학 유동충 재료 ( 무기 , 유기 , 고분자 ) : 구형의 형태를 가지는 푸른색 발광 BAM 형광체
강윤찬(Yun Chan Kang),노현숙(Hyun Sook Roh),박승빈(Seung Bin Park) 한국화학공학회 1999 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.37 No.6
The blue emitting BAM phosphor particles with various compositions were prepared by the spray pyrolysis. The effect of composition on the morphology of BAM particles was investigated. In the case of BaMgAl_(10)O_(22):Eu^(2+), the morphology of particles with sphericity and non-aggregation characteristics disappeared after post-treatment at 1,400 ℃ for 3 hrs. On the other hand, the other composition particles except BaMgAl_(10)O_(22):Eu^(2+) maintained their original morphology after posttreatment, even if the particles were prepared at low temperatures in the spray pyrolysis. The BAM particles with MgAl₂O₄as intermediate material at low post-treatment temperature had high thermal stability and maintained sphericity of particles after post-treatment. The BAM particles had submicron size and narrow size distribution before and after post-treatment. All the samples had main emission peak at 450 ㎚, which corresponds to blue emission. The optimum post-treatment temperature of BAM : Eu²+ particles for the maximum PL(photoluminescence) intensity in the spray pylolysis was 1,400 ℃ because of high crystallinity, phase-purity, and good morphology.
분체공학 유동층 재료 ( 무기 , 유기 , 고분자 ) / 기상법에 의해 제조한 YAG : Cr 형광체
강윤찬(Kang Yun Chan),정윤섭(Chung Yun Seup),박승빈(Park Seung Bin) 한국화학공학회 2000 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.38 No.1
Chromium-doped Yttrium Aluminum Garnet(YAG) phosphor particles, which generate red light when excited with e-beam or UV, were prepared from mixed nitrate solutions by spray pyrolysis using the FEAG process, and their characteristics were investigated. The prepared particles had an amorphous phase, which turned into phase pure YAG particles after annealing above 1,100℃. The prepared particles had spherical morphology, submicron size, and narrow size distribution without milling process. The mean size of the YAG : Cr particles varied from 0.34 to 0.83 ㎛ when the overall solution concentrations were changed from 0.01 to 0.2 M. The particles calcined below 1,200℃ maintained spherical morphology, but aggregation between particles was occurred after calcination above 1,400℃. The particles calcined at 1,500 ℃ had hard aggregation. The optimum doping concentration of Cr and calcination temperature for the maximum brightness of phosphor particles was 2 at% and 1,400 ℃, respectively.
단신 : 수산화칼슘 현탁액의 탄산화 반응에 의한 침상형 탄산칼슘 입자 제조
강윤찬(Yun Chan Kang),박진(Jin Park),박승빈(Seung Bin Park) 한국화학공학회 1997 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.35 No.2
A new carbonation process to prepare needle-like calcium carbonate particles from calcium hydroxide suspension without additives was proposed, and the effect of reaction conditions such as suspension concentration, reaction temperature, gas concentration, gas flow rate on the size of needle-like particles were investigated. Needle-like calcium carbonate particles were dominantly prepared at concentrations above 100g/ℓ. The length of particles was varied from submicron to 3 micron depending on the reaction conditions, and the aspect ratio was 10. The needle-like particles consist of unstable aragonite and stable calcite crystals. The length of particles was not influenced by the CO₂ gas concentrations in the range of 20 to 35 %. Needle-like particles were prepared at temperatures above 22℃, and the length of particles was increased with increasing the reaction temperatures. The length of particles were decreased with increasing the gas flow rate.