- Synthesis of Fine Copper Powders from CuO-H2O Slurry by Wet-reduction Method
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Jong-Gwan Ahn, Dong-Jin Kim, Ik-Kyu Lee, Jaeryeung Lee, Liang Huanzhen
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J Korean Powder Metall Inst. 2005;12(3):192-200.
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DOI: https://doi.org/10.4150/KPMI.2005.12.3.192
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 Abstract
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- Ultrafine copper powder was prepared from CuO-H_2O slurry with hydrazine, a reductant, under 70°C. The influence of various reaction parameters such as temperature, reaction time, molar ratio of N_2H_4, PvP and NaOH to Cu in aqueous solution had been studied on the morphology and powder phase of Cu powders obtained. The production ratio of Cu from CuO was increased with the ratio of N_2H_4/Cu and the temperature. When the ratio of N_2H_4/Cu was higher than 2.5 and the temperature was higher than 60°C, CuO was completely reduced into Cu within 40 min. The crystalline size of Cu obtained became fine as the temperature increase, whereas the aggregation degree of particles was increased with the reaction time. The morphology of Cu powder depended on that of the precursor of CuO and processing conditions. The average particle size was about 0.5µm.
- Synthesis of Flake Ag Powder by Polyol Process
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Dong-Jin Kim, Huanzhen Liang, Jong-Gwan Ahn, Jae-Ryeong Lee, Hun-Saeng Chung
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J Korean Powder Metall Inst. 2004;11(6):477-485.
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DOI: https://doi.org/10.4150/KPMI.2004.11.6.477
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Abstract
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- Monodispersed flaky silver powder was obtained by controlling the ratios of H_2O_2/NH_3 and Agin in a mixed solution of ethylene glycol and ammonia with an addition of PVP. The effects of NH_3/Ag,; H_2O_2/Ag;and;H_2PtCl_6/Ag on its morphology and size were investigated. In H_2O_2-NH_3-AgNO_3;system,;NH_3/Ag molar ratio was found to be an important reaction factor for the nucleation and crystal growth of Ag powder. The synthesis of flaky powder was optimized at over 6 of NH_3/Ag ;and;5;of;H_2O_2/Ag;under;1.0times10-3;of;Pt/Ag.;Moreover,;as;the; NH_3/Ag molar ratio increased, the size of precipitates was increased regardless of the amount of Pt. In the absence of H_2PtCI, the morphology and size of reduced Ag powder were found to be irregular in shape 2-4µm in diameter. However, homogenized fine Ag powder was obtained due to heterogeneous nucleation when H_2PtCI used as a cat-alyst, and flaky one was synthesized with the addition of Pt over 1.0times10-3 of Pt/Ag.
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