• 제목/요약/키워드: fine powders

검색결과 493건 처리시간 0.028초

감압 상태 순환유동층 반응기에서 플라즈마 그래프팅에 의한 미세입자 표면 개질 (Surface Modification of Fine Particle by Plasma Grafting in a Circulating Fluidized Bed Reactor under Reduced Pressure)

  • 박성희
    • Korean Chemical Engineering Research
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    • 제53권5호
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    • pp.614-619
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    • 2015
  • 미세입자의 플라즈마 표면 개질을 감압상태하의 순환유동층 반응기에서 수행하였다. 플라즈마에 의해 처리된 폴리스타이렌 입자는 폴리에틸렌글리콜로 표면에 그래프팅하였다. 표면 개질 전 입자와 플라즈마 처리된 입자 그리고 그래프팅된 입자의 특성은 각각 DPPH 방법, FTIR, SEM 그리고 접촉각 측정으로 분석하였다. 플라즈마 처리된 폴리스타이렌 입자의 표면에 과산화물이 잘 형성되었다. 또한, 폴리에틸렌글리콜의 그래프팅 중합에 의해 플라즈마 처리된 입자 표면에 그래프팅이 잘 분산되었다. 따라서 감압상태의 순환 유동층 반응기에서 플라즈마 처리에 의한 PEG-g-PS 입자를 성공적으로 형성할 수 있었다.

저온 분무 열분해법으로 제조된 Sr-ferrite의 자기특성 (Magnetic Properties of Sr-ferrite Powders via Modified Low Temperature Co-spray Roasting Process)

  • 김효준;조태식;남효덕;양충진
    • 한국전기전자재료학회논문지
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    • 제11권10호
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    • pp.931-939
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    • 1998
  • Preparation of the hexagonal Sr-ferrite powsers with high performance by co-spraying precusor of the FeCl$_2$+SrCO$_3$ at a low temperature was proved as a cost =-effective method. The co-spray roasting was carried out in the temperature range of 300~$700^{\circ}C$ after SrCO$_3$ powders were mixed into 12FeCi$_2$.4$H_2O$ liquor. By this low temperature roasting method fine particles of multi-phased FeO$_2$+SrCO$_3$ were formulated. Powders calcined at 105$0^{\circ}C$ for 1 hour show the best magnetic property of M\ulcorner=69.96 emu/g, M\ulcorner=36.98 emu/g, and \ulcornerH\ulcorner=4.31 Oe. This calcining temperature is lower than that of the conventional dry method by 10$0^{\circ}C$.

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Synthesis of Homogeneous La0.8Sr0.2CrO3 Powders Using an Ultrasonic Spray Pyrolysis Method

  • Kim, Chang-Sam;Hwang, Seong-Ik;Kim, Shin-Woo
    • 한국세라믹학회지
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    • 제44권5호
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    • pp.148-150
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    • 2007
  • A process to synthesize $La_{0.8}Sr_{0.2}CrO_3$ (LSC), which is a promising material for use as a separator in a soild oxide fuel cell, is investigated in this study. LSC powders without secondary Phases could be synthesized with ultrasonic spray pyrolysis and a heat treatment at $1200^{\circ}C$ for 20 h; however, it showed an average diameter of $0.6{\mu}m$ with a wide particle size distribution. On the other hand, LSC powders synthesized with spray pyrolysis at $800^{\circ}C$, heat-treated at $900^{\circ}C$ for 5 h, ball-milled and finally heat-treated again at $1200^{\circ}C$ for 20 h showed a smaller average diameter of $0.3{\mu}m$ and narrower size distribution. Very few particles above $0.5{\mu}m$ were found. Thus, a proper combination of the heat treatment and milling process after spray pyrolysis it determined to be very important in synthesizing fine and uniform LSC perovskite powders.