- Study of Hydrolysis of Al Powder and Compaction of Nano Alumina by Spark Plasma Sintering(SPS)
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Y. Uhm, M. Lee, C. Rhee
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J Korean Powder Metall Inst. 2005;12(6):422-427.
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DOI: https://doi.org/10.4150/KPMI.2005.12.6.422
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 Abstract
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- The Al_2O_3 with various phases were prepared by simple ex-situ hydrolysis and spark plasma sintering (SPS) process of Al powder. The nano bayerite (beta-Al(OH)_3) phase was derived by hydrolysis of commercial powder of Al with micrometer size, whereas the bohemite (AlO(OH)) phase was obtained by hydrolysis of nano Al powder synthesized by pulsed wire evaporation (PWE) method. Compaction as well as dehydration of both nano bayerite and bohemite was carried out simultaneously by SPS method, which is used to fabricate dense powder compacts with a rapid heating rate of 100°C per min. under the pressure of 50MPa. After compaction treatment in the temperature ranges from 100°C;to; 1100°C, the bayerite and bohemite phases change into various alumina phases depending on the compaction temperatures. The bayerite shows phase transition of Al(OH)_3toeta-Al_2O_3totheta-Al_2O_3toalpha-Al_2O_3 sequences. On the other hand, the bohemite experiences the phase transition from AlO(OH) to gamma-Al_2O_3;at;350°C. It shows AlO(OH) gamma-Al_2O_3todelta-Al_2O_3toalpha-Al_2O_3 sequences. The gamma-Al_2O_3 compacted at 550°C shows a high surface area (138m2/g).
- The study of Synthesis of Dihydropyrimidine for Cardiotropic Drugs Using New Catalysts on the Basis of Nano Cu Oxides
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Y. Uhm, M. Lee, C. Rhee
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J Korean Powder Metall Inst. 2005;12(6):441-446.
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DOI: https://doi.org/10.4150/KPMI.2005.12.6.441
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Abstract
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- The copper oxide nano powders were synthesized by levitational gas condensation (LGC) method, and were applied to catalyst to fabricate 3,4-dihydropyrimidin-2-(1H)-one. Processes of adsorption of Biginelli reaction reagents on the copper nanooxide surface Cu_2O°CuO were studied by IR-spectroscopy. It was shown that benzaldehyde coordination, acetoacetic ether on the oxide surface is carried out with participation of carbonyl fragments, urea by N-H bonds which affects positively on the reagents reactivity.
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