• 제목/요약/키워드: Powder Morphology

검색결과 567건 처리시간 0.026초

무전해 니켈 도금법으로 제조된 니켈-다이아몬드 복합분체의 특성 (Characteristics of Nickel-Diamond Composite Powders by Electroless Nickel Plating)

  • 안종관;김동진;;이재령;이익규;정헌생
    • 한국분말재료학회지
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    • 제11권3호
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    • pp.224-232
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    • 2004
  • Ni-diamond composite powders with nickel layer of round-top type on the surface of synthetic diamond (140/170 mesh) were prepared by the electroless plating method (EN) with semi-batch reactor. The effects of nickel concentration, feeding rates of reductant, temperature, reaction time and stirring speeds on the weight percentage and morphology of deposited Ni, mean particle size and specific surface area of the composite powders were investigated by Atomic Adsortion Spectrometer, SEM-EDX, PSA and BET. It was found that nucleated Ni-P islands, acted as catalytic sites for further deposition and grown into these relatively thick layers with nodule-type on the surface of diamond by a lateral growth mechanism. The weight percentage of Ni in the composite powder increased with reaction time, feeding rate of reductant and temperature, but decreased with stirring speed. The weight percentage of Ni in Ni-diamond composite powder was 55% at 150 min., 200 rpm and 7$0^{\circ}C$ .

고체 전해커패시터용 니오븀 분말제조 (Fabrication of Niobium Powder for Solid-electrolyte Capacitors)

  • 윤재식;황선호;김병일
    • 한국표면공학회지
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    • 제42권5호
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    • pp.227-231
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    • 2009
  • The niobium capacitor showed somewhat more unstable characteristics than the commercial tantalum capacitors, but is nonetheless considered applicable as a future substitute for tantalum capacitors. In this study, niobium powder was fabricated by metallothermic reduction process using $K_2NbF_7$ as the raw materials, KCl and KF as the diluents and Na as the reducing agent. The niobium particle size greatly decreased from 0.7um to 0.2 um as the amount of diluent increased. However if a higher surface area of powder is required, more diluents need to be used in the said method in order to produce niobium powder. The niobium powder morphology and particle size are very sensitive to a amount of sodium excess. The particle size of niobium powder increased with a increasing amount of sodium excess. When more diluent and sodium are used, the niobium powder will be contaminated with more impurities such as Fe, Cr, Ni so on.

방전플라즈마 소결법으로 제작된 순 마그네슘 분말 소결체의 특성평가 (Characteristics of Pure Mg Powder Compacts Prepared by Spark Plasma Sintering Process)

  • 홍지민;손현택;장세훈;이재설;차용훈;오익현
    • 한국재료학회지
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    • 제17권6호
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    • pp.331-336
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    • 2007
  • The pure Mg powder compacts were successfully fabricated using SPS process. The machined chip powder showed flake shaped morphology with coarse surfaces, while gas atomized powders were spherical in morphology with smooth surfaces. In this study, SPS process was used to consolidate the pure Mg powder because this process allows high density consolidation in a short time. The results showed that increased sintering temperature from $350^{\circ}C$ to $500^{\circ}C$ with pressure of 30MPa, the maximum values of the density was increased from 98.1% to 99.8% of theoretical density, respectively. However, density of the sintered chip powders was higher than that of gas-atomized powder due to larger contact areas between particles.

SiAlON 원료분말제조를 위한 분무건조 과립분말의 형상과 크기에 미치는 공정변수효과 (Effect of Process Parameters on the Morphology and Size of Spray-Dried Granule Powder for Fabrication of SiAlON Raw Material)

  • 최재형;이소율;한윤수;이성민;남산;김성원
    • 한국재료학회지
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    • 제27권12호
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    • pp.716-721
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    • 2017
  • SiAlON-based ceramics are some of the most typical ceramic materials used as cutting tools for HRSA(Heat Resistant Super-Alloys). SiAlON can be fabricated using ceramic processing, such as mixing, granulation, compaction, and sintering. Spray drying is a widely-used method for producing a granular powder of controlled morphology and size with flowability. In this study, we report a systematic investigation aimed at optimizing spherical granule morphology by controlling spray-drying parameters such as gas flow and feed rate. Before spray drying, the viscosities of the raw material slurries were also optimized with the amount of dispersant added.

MR-EMR 복합공정에 의한 탄탈륨분말의 제조시 온도변화에 따른 분말의 특성 (Characteristics of Powder with Change of Temperature in Production of Tantalum Powder by MR-EMR Combination Process)

  • 배인성;윤재식;박형호;윤동주;이민호;설경원;김병일
    • 한국분말재료학회지
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    • 제10권6호
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    • pp.395-405
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    • 2003
  • In the conventional metallothermic reduction (MR) process for obtaining tantalum powder in batch-type operation. it is difficult to control morphology and location of deposits. On the other hand, a electronically mediated reaction (EMR) process is capable to overcome these difficulties and has a merit of continuous process, but it has the defect that the reduction yield is poor. MR-EMR combination process is a method that is able to overcome demerits of MR and EMR process. In this study, a MR-EMR combination process has been applied to the production of tantalum powder by sodium reduction of $K_2$TaF$_{7}$. The total charge passed through external circuit and average particle size (FSSS) were increased with increasing reduction temperature. The proportion of fine particle (-325 mesh) was decreased with increasing reduction temperature. The yield was improved from 65% to 74% with increasing reduction temperature. Considering the charge, impurities, morphology, particle size and yield, an reduction temperature of 1,123 K was found to be optimum temperature for MR-EMR combination process.

금속열환원 공정에서 반응온도가 니오븀 분말 특성에 미치는 영향 (The Effect of Reduction Temperature on the Characteristic Variation of Niobium Powder During Metallothermic Reduction Process)

  • 윤재식;이영미;황선호;김병일
    • 한국분말재료학회지
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    • 제16권2호
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    • pp.104-109
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    • 2009
  • Niobium powder was made from potassium heptafluoroniobite ($K_2NbF_7$) as the raw material using sodium (Na) as a reducing agent based on the hunter process. The apparatus for the experiment was designed and built specifically for the present study. The niobium particle size greatly increased as the reduction temperature increased from $710^{\circ}C$ to $800^{\circ}C$. The particle size was fairly uniform, varying from $0.09{\mu}m$ to $0.4{\mu}m$ depending on the reduction temperatures. The niobium powder morphology and particle size are very sensitive to a reaction temperature in the metallothermic reduction process. The yield of niobium powder increased from 55% to 80% with a increasing a reaction temperature.

β-SiC 분말 Seeds가 Sol-gel 공정으로 합성된 고순도 β-SiC 분말 형상 및 크기에 미치는 영향 (Effects of β-SiC Particle Seeds on Morphology and Size of High Purity β-SiC Powder Synthesized using Sol-Gel Process)

  • 김규미;조경선;박상환
    • 한국세라믹학회지
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    • 제46권5호
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    • pp.528-533
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    • 2009
  • High purity $\beta$-SiC powders were synthesized using sol-gel processing. TEOS and phenol resin were used as the starting material for the silicon source and carbon source, respectively. The process turned out to be capable of producing high purity SiC powder purity degree with 99.98 %. However, it was difficult to control the shape and size of $\beta$-SiC powders synthesized by sol-gel process. In this study, $\beta$-SiC powder with size of $1{\sim}5$ um an 30 nm were used as the seeds for $\beta$-SiC to control the $\beta$-SiC powder morphology. It was found that $\beta$-SiC powder seeds was effective to increase the powder average size of synthesized $\beta$-SiC using sol-gel process by acting as the preferred growing sites for $\beta$-SiC.

TiO2 나노분말 제조시 HCI과 NH4OH의 첨가량에 따른 반응양상과 pH의 영향 (Reaction morphology depending on the amounts of HCl and NH4OH and effect of pH on the preparation of TiO2 nanopowder)

  • 임창성;오원춘
    • 분석과학
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    • 제20권4호
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    • pp.302-307
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    • 2007
  • $TiO_2$ 나노분말 제조시 HCl과$NH_4OH$의 첨가량에 따른 반응양상과 pH의 영향을 고찰하였다. Titanium tetra-isopropoxide의 가수분해 반응을 이용하여 nanosize의 $TiO_2$ 분말를 합성하였고, 촉매로 HCl과$NH_4OH$를 사용하였다. 촉매의 첨가량에 따른 반응양상과 생성된 $TiO_2$ 분말의 특성 변화를 조사하였다. 염기성 촉매인$NH_4OH$를 사용하였을 경우에 균질한 형상의 분말 형태의 $TiO_2$를 합성할 수 있었으며, 산성 촉매인 HCl을 사용하여 pH가 5.04 이하일 경우에는 괴상이나 과립의 형태로 생성되었다. 사용한 촉매의 종류와 양에 따라 저온의 결정상인 anatase의 생성속도와 보다 안정한 rutile 상으로의 상전이 속도가 영향을 받았다.

Hydrothermal Synthesis of Rod-like Copper Oxide Crystals

  • Pee, Jae-Hwan;Lee, Dong-Wook;Kim, Ung-Soo;Choi, Eui-Seok
    • 한국분말야금학회:학술대회논문집
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    • 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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    • pp.167-168
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    • 2006
  • A hyrdrothermal synthesis has been developd to prepare rod-like crystals of copper oxide using copper nitrate trihydrate as a function of synthesis temperature, stirring speed and solution pH value. The properties of the fabricated crystals were studied using scanning electron microscopy, X-ray diffraction and particle size analysis. The morphology of the synthesized CuO was dependent on both the pH value of the solution and the morphology of the seed materials. Synthesized particles have regular morphologies and a uniform size distribution.

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