• Title/Summary/Keyword: 나노분말 합성

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Structural and Electrochemical characterization of LiCoO2 Nano Cathode Powder Fabricated by Mechanochemical Process (기계 화학법에 의해 제작된 나노 LiCoO2 양극 분말의 구조 및 전기화학적 특성)

  • Choi, Sun-Hee;Kim, Joo-Sun;Yoon, Young-Soo
    • Journal of the Korean Ceramic Society
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    • v.41 no.1
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    • pp.86-91
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    • 2004

  • $LiCoO_2$ cathode powders with round particle shaped and nano grain sized of 70-300nm were synthesized by a mechanochemical method. The surface of Li-Co precursor prepared by freeze drying method was modified by $K_2SO_4$ coating and ball milling was used for the coating process. The precursor was crystallized to high temperature form of $LiCoO_2$ at $800^{\circ}C$ and the grain growth was inhibited by the $K_2SO_4$ coating effect. The $K_2SO_4$ coating was not decomposed at $800^{\circ}C$ and prevented the contact in the Li-Co precursor particles. The nano-sized $LiCoO_2$ powder had tetragonal phase and it affected the Li diffusion through the surface of particles. It means that the anode materials for hight performance battery should be satisfied not only small particle size but phase contol on the surface of particles. In this study, the powder characteristics and rate capabilities were compared with a commercial powder and the nano-sized $LiCoO_2$ powder fabricated by the mechanochemical method. And the crucial factor which affects on battery performance was also examined.

  • https://doi.org/10.4191/KCERS.2004.41.1.086 인용 PDF KSCI

Preparation and Characterization of Tungsten Carbide Using Products of Hard Metal Sludge Recycling Process (초경합금 슬러지 재활용 공정 산물을 활용한 텅스텐 탄화물 제조 및 특성 평가)

  • Kwon, Hanjung;Shin, Jung-Min
    • Resources Recycling
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    • v.31 no.4
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    • pp.19-25
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    • 2022

  • In this study, tungsten carbide (WC) powder was prepared using a novel recycling process for hard metal sludge that does not use ammonium paratungstate. Instead of ammonia, acid was used to remove the sodium and crystallized tungstate, resulting in the formation of tungstic acid (H2WO4). The WC powder was successfully synthesized by the carbothermal reduction of tungstic acid through H2O decomposition, reduction of WO3 to W, and formation of WC. The carbon content and holding time at the carbothermal reduction temperature were optimized to remove free carbon from the WC powder. As a result, most of the free carbon in the WC powder prepared from sludge was removed, and the content of free carbon in the synthesized WC powder was lower than that in commercial WC powder. Moreover, the crystallite size of WC prepared from H2WO4 was much smaller than that of commercial micron-sized WC powder produced from APT. The small crystallite size of WC induces grain growth during the sintering of the WC-Co composite; thus, a WC-Co composite with large WC grains was fabricated using the WC powder prepared from H2WO4. The large WC grains affected the mechanical properties of the WC-Co composite. Further, due to the large grain size, the WC-Co composite fabricated from H2WO4 exhibited a higher toughness than that of the WC-Co composite prepared from commercial WC powder.

  • https://doi.org/10.7844/kirr.2022.31.4.19 인용 PDF KSCI