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Dolomite 로 부터 고토인안비료 제조의 기초적 연구
김창은 한국화학공학회 1972 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.10 No.1
This investigation was carried out to produce a high quality magnesium compounded fertilizer by initially dissolving calcined dolomite in sea water to form the intermediate Mg(OH)₂ precipitate, and reacting this intermediate with phosphoric acid and ammonia thereafter. The experimental results were obtained as follows; 1) The optimum calcination temperature of dolomite was about 950℃ for 30 minutes operation and in the displacement of the calcined dolomite in sea water, the optimum mole ratio of calcium hydroxide to magnesium chloride is 1:1.2 for 4 hours of the dissolution time. 2) The high yield of the magnesium compounded fertilizer was obtained, when the precipitate was reacted with 20% phosphoric acid and neutralized with 28% ammonium hydroxide thereby obtaining the alkalinity of the solution to pH 9. 3) By the results of X-ray diffraction and chemical analysis, the major component of the product was magnesium ammonium phosphate at the above condition and the fertilizing effect was also good.
Al-Sec-Butoxide의 가수분해시에 있어서 $\alpha$-$Al_2O_3$종의 동시첨가에 의한 열적 전이거동
김창은,이해욱,최진관,김배연 한국세라믹학회 1990 한국세라믹학회지 Vol.27 No.6
The thermal behavior of transformation and characteristics of seeded sample powders prepared by simultaneous $\alpha$-Al2O3 seed addition with water on the Al-sec-butoxide hydrolysis were studied. $\alpha$-Al2O3 seed particles are shown to act as nuclei for transformation of $\theta$-to $\alpha$-Al2O3 and to result in an increase in thetransformation kinetics and lowering of the transformation temperature by as much as 143$^{\circ}C$. Simultaneous seed addition on the hydrolysis resulted in uniform dispersin and creation of nucleation site on seed surface and only 0.1wt% seeding lowered the transformation temperature by as much as 115$^{\circ}C$. For 3wt% seed addition, $\alpha$-Al2O3 single phase was obtained at 95$0^{\circ}C$ for 100 minutes and the specific surface area of products were lowered to 11.9$m^2$/g as compared with that of $\alpha$-Al2O3 powder prepared without seed at 115$0^{\circ}C$ ; 15.1$m^2$/g due to depression of vermicular structure growth.
침전법으로 제조한 Hydroxyapatite Ceramics의 기계적 성질
김창은,편영범,김배연,박훈,Kim, Chang-Eun,Pyeon, Young-Beom,Kim, Bae-Yeon,Park, Hoon 한국세라믹학회 1989 한국세라믹학회지 Vol.26 No.2
The effects of starting composition, sintering temperature and porosity on the mechanical properties of hydroxyapatite ceramics were investigated. The hydroxyapatite powder were prepared by precipitation method using Ca(NO3)2.4H2O and (NH4)2.HPO4. The obtained powders were Ca-deficient hydroxyapatites and as the Ca/P mole ration in the initial solution was increased, the particle size of the precipitates was decreased, and the decomposition of hydroxyapatite to $\beta$-TCP was controlled. The porosity, as well as Ca/P mole ratio in starting composition and sintering temperature, plays major role in the mechanical properties of dense hydroxyapatite ceramics.