• 제목/요약/키워드: slurry mixing and hydrogen reduction

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화학용액혼합과 수소환원법으로 제조된 나노 구조 Fe-Co 합금분말의 미세구조 및 자성 특성 (Microstructure and Magnetic Properties of Nanostructured Fe-Co Alloy Powders Produced by Chemical Solution Mixing and Hydrogen Reduction Methods)

  • 박현우;이백희;이규환;김영도
    • 한국분말재료학회지
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    • 제10권5호
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    • pp.333-336
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    • 2003
  • The purpose of this study is the fabrication of nano-sized Fe-Co alloy powders with soft magnetic properties by the slurry mixing and hydrogen reduction (SMHR) process. $FeCl_2$0 and $CoCl_2$ powders with 99.9% purities were used for synthesizing nanostructured Fe-Co alloy powder. Nano-sized Fe-Co alloy powders were successfully fabricated using SMHR, which was performed at 50$0^{\circ}C$ for 1 h in H$_2$ atmosphere. The fabricated Fe-Co alloy powders showed $\alpha$' phase (ordered body centered cubic) with the average particle size of 45 nm. The SMHR powder exhibited low coercivity force of 32.5 Oe and saturation magnetization of 214 emu/g.

Preparation of Fine Co Powder from Co(OH)2 Slurry by Hydrothermal Reduction with Hydrogen

  • Kening Yu;Kim, Dong J.;Hun S. Chung
    • 한국결정성장학회:학술대회논문집
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    • 한국결정성장학회 1996년도 제11차 KACG 학술발표회 Crystalline Particle Symposium (CPS)
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    • pp.87-107
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    • 1996
  • The fine Co powder with an average particle sie of less than 1$\mu\textrm{m}$ was prepared by hydrothermal reduction with hydrogen from Co(OH)2 slurry obtained by mixing the solutons of CoSO4$.$7H2O and NaOH. A method to control pH of the end solution around neutrality was proposed. The reduction rate was found to be a function of pH, temperature, hydrogen pressure and the amount of catalyst.

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Synthesis of Nanostructured Fe-Co Alloy Powders from Metal Salts

  • Lee, Young-Jung;Lee, Jea-Sung;Seo, Young-Ik;Kim, Young-Do
    • 한국분말재료학회지
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    • 제13권5호
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    • pp.336-339
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    • 2006
  • Magnetic properties of nanostructured materials are affected in complicated manner by their microstructure such as pain size (or particle size), internal strain and crystal structure. Thus, studies on the synthesis of nanostructured materials with controlled microstructure are necessary fur a significant improvement in magnetic properties. In the present work, nanostructured Fe-Co alloy powders with a grain size of 50 nm were successfully fabricated from the powder mixtures of (99.9% purity) $FeCl_2$ and $CoCl_2$ by chemical solution mixing and hydrogen reduction.

금속산화물 복합분말의 동결건조 및 수소분위기 환원처리에 의한 Cu-Sn 다공체 제조 (Synthesis of Porous Cu-Sn by Freeze Drying and Hydrogen Reduction Treatment of Metal Oxide Composite Powders)

  • 김민성;유호석;오승탁;현창용
    • 한국재료학회지
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    • 제23권12호
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    • pp.722-726
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    • 2013
  • Freeze drying of a porous Cu-Sn alloy with unidirectionally aligned pore channels was accomplished by using a composite powder of CuO-$SnO_2$ and camphene. Camphene slurries with CuO-$SnO_2$ content of 3, 5 and 10 vol% were prepared by mixing with a small amount of dispersant at $50^{\circ}C$. Freezing of a slurry was done at $-25^{\circ}C$ while the growth direction of the camphene was unidirectionally controlled. Pores were generated subsequently by sublimation of the camphene during drying in air for 48 h. The green bodies were hydrogen-reduced at $650^{\circ}C$ and then were sintered at $650^{\circ}C$ and $750^{\circ}C$ for 1 h. XRD analysis revealed that the CuO-$SnO_2$ powder was completely converted to Cu-Sn alloy without any reaction phases. The sintered samples showed large pores with an average size of above $100{\mu}m$ which were aligned parallel to the camphene growth direction. Also, the internal walls of the large pores had relatively small pores. The size of the large pores decreased with increasing CuO-$SnO_2$ content due to the change of the degree of powder rearrangement in the slurry. The size of the small pores decreased with increase of the sintering temperature from $650^{\circ}C$ to $750^{\circ}C$, while that of the large pores was unchanged. These results suggest that a porous alloy body with aligned large pores can be fabricated by a freeze-drying and hydrogen reduction process using oxide powders.

NiO/camphene 슬러리의 동결건조 및 수소환원 공정에 의한 Ni 다공체 제조 (Fabrication of Porous Ni by Freeze Drying and Hydrogen Reduction of NiO/Camphene Slurry)

  • 정재헌;오승탁;현창용
    • 한국분말재료학회지
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    • 제26권1호
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    • pp.6-10
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    • 2019
  • In this study, freeze drying of a porous Ni with unidirectionally aligned pore channels is accomplished by using a NiO powder and camphene. Camphene slurries with NiO content of 5 and 10 vol% are prepared by mixing them with a small amount of dispersant at $50^{\circ}C$. Freezing of a slurry is performed at $-25^{\circ}C$ while the growth direction of the camphene is unidirectionally controlled. Pores are generated subsequently by sublimation of the camphene during drying in air for 48 h. The green bodies are hydrogen-reduced at $400^{\circ}C$ and then sintered at $800^{\circ}C$ and $900^{\circ}C$ for 1 h. X-ray diffraction analysis reveals that the NiO powder is completely converted to the Ni phase without any reaction phases. The sintered samples show large pores that align parallel pores in the camphene growth direction as well as small pores in the internal walls of large pores. The size of large and small pores decreases with increasing powder content from 5 to 10 vol%. The influence of powder content on the pore structure is explained by the degree of powder rearrangement in slurry and the accumulation behavior of powders in the interdendritic spaces of solidified camphene.

Co 질산염과 TiO(OH)2 슬러리를 이용한 초미립 TiC-5%Co 제조 및 WC-Co 분말과의 혼합에 따른 소결체 특성 (Synthesis of Ultrafine TiC-5%Co Powder by Using Co Nitrate and TiO(OH)2 Slurry and Evaluation of Sintered Materials Prepared by Mixing WC-Co)

  • 홍성현;김병기
    • 한국분말재료학회지
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    • 제15권2호
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    • pp.107-113
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    • 2008
  • Ultrafine TiC-5%Co powders were synthesized by spray drying of aqueous solution of TiO$(OH)_2$ slurry and cobalt nitrate, followed by calcination and carbothermal reaction. The oxide powders with carbon powder was reduced and carburized at $900^{\circ}C{\sim}1250^{\circ}C$ under hydrogen atmosphere. During reduction, CO gas was mainly evolved by reducing reaction of oxides. Ultrafine TiC-5%Co powders were easily formed by carbothermal reaction at $1250^{\circ}C$ due to using ultrafine powders as raw materials. The ultrafine WC-TiC-Co alloy prepared by sintering of mixed powder of ultrafine WC-13%Co powder and ultrafine TiC-5%Co powder has higher sintered density and mechanical properties than WC-TiC-Co alloy prepared by commercial WC, TiC and Co powders.