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이기정(Kee Jeung Lee),서경원(Kyung Won Seo) 한국화학공학회 1997 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.35 No.5
Powders of crystalline α-SiO₂(α-quartz), having the mean particle size of 1-10 ㎛with shapes of rhombohedron, were prepared by hydrothermal synthesis in the temperature range of 250-450 ℃ for a 3 h reaction. `1`he reaction temperature could be reduced as the concentration of a mineralizer increased. Experimental results showed that the particle size became smaller with its narrow distribution as the concentration of a mineralizer increased. However, the particle size became larger with its wide distribution as the concentration of nutrients and the reaction temperature increased. Both of the nucleation and the crystal growth rate also became faster and the particle size became larger as the reaction temperature increased. The above results were expressed as a characteristic equation for the weight mean particle diameter(S) of synthetic powders, such as S◎1.57 exp(-E_a/RT)·t^(0.11)·C^(0.33)_M·C^(0.22)_N·C^(0.08)_S with the activation energy, E_a was 8.15 kJ/g㏖K.
고온 수용액으로부터의 고품질 α-Quartz 분말 제조
이기정(Kee Jeung Lee),서경원(Kyung Won Seo),목영일(Young Il Mok),유효신(Hyo Shin Yu) 한국화학공학회 1997 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.35 No.2
In this study powders of high quality α-quartz(α-SiO₂) crystal having uniform particle sizes und high crystallinity were prepared under hydrothermal conditions. The α-quartz powders were prepared after a 3 hours` operation in the temperature range of 300-450℃ and in the pressure range of 100-300atm. Alkali hydroxides and alkali halides such as KOH, NaOH. Na₂CO₃, KF and NaF were found to be effective in this reactions, which added in order to increase the solubility of amorphous silica feedstock. The α-quartz crystal powders were obtained in uniform size of 1-10㎛ with hexagonal structure. The characterization of the synthetic products were carried out using XRD, SEM, PSA, FTIR and Raman spectrometer.