• 제목/요약/키워드: particle size control

검색결과 608건 처리시간 0.033초

Dispersion stability of ultra-fine $BaTiO_3$ suspensions in aqueous medium

  • Chun, M.P.;Chung, Y.B.;Ma, Y.J.;Cho, J.H.;Kim, B.I.
    • 한국결정성장학회지
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    • 제15권6호
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    • pp.239-243
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    • 2005
  • The effect of pH and particle size on the dispersion stability of ultra-fine $BaTiO_3$ suspensions in aqueous medium have been investigated by means of zeta potential, sediment experiments, and powder properties (particle analysis, specific surface area) etc. Zeta potential as a function of pH for two particles of different size increases from -75 to +10 mV with decreasing pH from 8.5 to 1.4. The curve of zeta potential for small particle (150 nm) has slow slope than that of large particle (900nm), giving IEP (isoelectric point) value of pH=1.6 for small particle and pH=1.9 for large particle respectively, which means that it is more difficult to control zeta potential with pH fur small particle than large particle. The dispersion stability of $BaTiO_3$ particles in aqueous medium was found to be strongly related with the agglomeration of colloidal suspensions with time through the sedimentation behaviors of colloidal particles with time and pH value.

열전지 음극재용 Li-Si 원료의 성형성에 미치는 입자크기와 바인더첨가 효과 (Effects of Particle Size and Binder Phase Addition on Formability of Li-Si Alloy Powder for Thermal Battery Anode)

  • 류성수;김희식;김성원;김형태;정해원;이성민
    • 한국분말재료학회지
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    • 제21권5호
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    • pp.331-337
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    • 2014
  • The effects of particle size of Li-Si alloy and LiCl-KCl addition as a binder phase for raw material of anode were investigated on the formability of the thermal battery anode. The formability was evaluated with respect to filling density, tap density, compaction density, spring-back and compressive strength. With increasing particle size of Li-Si alloy powder, densities increased while spring-back and compressive strength decreased. Since the small spring-back is beneficial to avoiding breakage of pressed compacts, larger particles might be more suitable for anode forming. The increasing amount of LiCl-KCl binder phase contributed to reducing spring-back, improving the formability of anode powder too. The control of particle size also seems to be helpful to get double pressed pellets, which consisted of two layer of anode and electrolyte.

입도와 흑연 첨가제에 따른 유해 입자 및 가스 동시제거용 세라믹필터 특성평가 (Characteristics of the Ceramic Filter with the Control of Particle Size and Graphite Additive for the Hazardous Particle and Gas Removal)

  • 조을훈;이근재
    • 한국분말재료학회지
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    • 제21권6호
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    • pp.454-459
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    • 2014
  • In this study, the porous ceramic filter was developed to be able to remove both dust and hazardous gas contained in fuel gas at high temperature. The porous ceramic filters were fabricated and used as a catalyst support. And the effects have been investigated such as the mean particle size, organic content and addition of foaming agent on the porosity, compressive strength and pressure drop of ceramic filters. With the increase of mean powder size and the organic content for the cordierite filter, the porosity was increased, but the compressive strength and pressure drop were decreased. From the results of the research, the optimum condition for the fabrication of ceramic filters could be acquired and they had the porosity of 58%, the compressive strength of 13.4 MPa and the pressure drop of 250 Pa. It was expected that this ceramic filter was able to be applied to the glass melting furnace, combustor, and dust/toxic gas removal filter.

Effect of Wood Particle Size on Physical and Mechanical Composites by Nonwoven Web Process

  • Chae, Shoo Geun;Eom, Young Geun
    • Journal of the Korean Wood Science and Technology
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    • 제33권2호통권130호
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    • pp.40-55
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    • 2005
  • This study was carried out to discuss the feasibility of wood and plastic wastes as the raw materials for wood particle-plastic composites. For this purpose, composites were manufactured from coarse and fine wood particles and polypropylene fibers by nonwoven web process. And the effect of wood particle size on the performance of the composites were analyzed according to ASTM D 1037-93. In the physical properties of composites, water absorption decreased with the increase of target density and polypropylene fiber content. And the composites with fine wood particles appeared to have slightly lower water absorption than those with coarse wood particles. Thickness swelling did not vary significantly with the increase of target density but increased with the increase of wood particle content. And the composites with fine wood particles were significantly lower in thickness swelling than those with coarse wood particles. In the mechanical properties of composites, dry and wet MOR showed the increasing tendency with the increase of polypropylene fiber content and target density. Dry and wet MOE showed the increasing tendency with the increase of target density but only wet MOE exhibited the increasing tendency with the increase of polypropylene fiber content. Composites with fine wood particles appeared to be generally higher in wet MOR and MOE than those with coarse wood particles. In conclusion, composites with fine wood particles showed generally higher performance than those with coarse ones. Also, composites were significantly superior to control particleboards in the performance, especially in water absorption and thickness swelling.

Sheet형 전파흡수체에 있어 Ferrite 입자 크기의 제어에 따른 전파흡수체의 특성 (Electromagnetic Wave Absorption of Sheet Type EM Wave Absorber by Control of Ferrite Particle Size)

  • 김동일;옥승민;김수정;박우근;송재만
    • 한국항해항만학회지
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    • 제27권1호
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    • pp.71-74
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    • 2003
  • Sheet형 전파흡수체를 제조하고 그들의 전자파 흡수 특성을 조사하였다. 제조된 ferrite 흡수체의 흡수특성은 2.4~3.2GHz의 주파수범위에서 입자크기의 감소에 따라 개선되었다.

연료전지 촉매의 입자크기가 내구성에 미치는 영향 (Effect of Pt Particle Size on the Durability of PEMFC)

  • 민경원;김현종;한명근;류태우;김목순;주영환
    • 전기화학회지
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    • 제11권4호
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    • pp.313-318
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    • 2008
  • 본 연구에서는 백금의 입자크기가 내구성과 활성에 미치는 영향을 고찰하였다. 상용 Pt/C의 열처리를 통해 백금 입자 크기를 $3.5{\sim}9\;nm$로 조절하였고, XRD와 TEM을 통해 이를 확인하였다. 촉매의 내구성 분석을 위해 가속 실험을 실시하였고, 촉매 활성 측정을 위해 산소환원반응 실험을 하였다. 백금의 입자크기를 증가시킬수록 내구성은 향상되었으나 촉매의 활성이 저하되었다. 즉 촉매의 내구성과 활성은 반비례관계가 성립된다는 것을 확인하였다. 그리고 저하된 촉매 활성과 내구성을 향상시키기 위해, 합금 촉매를 사용하였다.상용 Pt/C의 최대 전력 밀도는 약 $507.6\;mV/cm^2$ 이고, PtCo/C 합금촉매는 $585.8\;mV/cm^2$이었다. 전기화학적 표면적은 상용 Pt/C는 약 60%정도 감소하였고, PtCo/C 합금촉매는 약 24%정도의 감소율을 나타냈다. 따라서 백금의 입자 크기 조절과 합금화를 통해 백금의 내구성과 활성을 동시에 높일 수 있었다.

커먼레일 직접분사식 디젤엔진에서 시분해 레이저 유도 백열법을 이용한 매연입자의 배출 특성 (The Characteristics of Exhausted Soot Particles from a Common-Rail Direct Injection Diesel Engine by TIRE-LII)

  • 김규보;한휘영;장영준;전충환
    • 한국자동차공학회논문집
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    • 제15권5호
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    • pp.78-85
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    • 2007
  • Recently, diesel vehicles have been increased and their emission standards have been getting strict. The emission of diesel vehicles contains numerous dangerous compounds, especially particulate matters cause a serious environmental pollutant and affect to human health seriously. Thousands of studies have already reported that particulate matters are associated with respiratory and cardiovascular diseases, and death. Due to these, it is necessary to measure the soot concentration and soot particle size in laboratory flames or practical engines to recognize the soot formation, and develop the control strategies for soot emission. In this study, the characteristics of exhausted soot particle size and volume fraction from 2.0L CRDI diesel engine have been investigated as varying engine speed and load. Laser induced incandescence has been used to measure soot concentration. Time-resolved laser induced incandescence has been used to determine soot particle size in the engine. The soot volume fraction is increased as increasing engine load but soot volume fraction is decreased as increasing engine speed. The primary particle size is distributed about $35nm{\sim}60nm$ at each experimental conditions.

세라믹 입자/알루미늄 소재의 연속복합 균일분산 (Continuous Combined Process for Homogeneous Dispersion of Ceramic Particle and Aluminum Materials)

  • 이동건;이승후;강충길
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2001년도 춘계학술대회 논문집
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    • pp.381-384
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    • 2001
  • The combined stirring method to uniform distribution of particle is consisted of two strring force both electro-magnetic stirring generated from induction heating and mechanical stirring with graphite stirrer. PMMC billets were fabricated with the volume fractions ranged from 0% to 20% and particle sizes ranged from 14$\mu\textrm{m}$ to 25$\mu\textrm{m}$. It is important to control the size of primary ${\alpha}$-AI solid particles because it could become the cause of the particle pushing or capture phenomena from the fact that secondary dendrite arm spacing size depends on the cooling rate during the solidification in hypoeutectic AI-Si alloy.

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Prediction of Packing Density of Milled Powder Based on Packing Simulation and Particle Shape Analysis

  • Amano, Yuto;Itoh, Takashi;Terao, Hoshiaki;Kanetake, Naoyuki
    • 한국분말야금학회:학술대회논문집
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    • 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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    • pp.1254-1255
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    • 2006
  • For precise property control of sintered products, it is important to understand accurately the packing density of the powder. We developed a packing simulation program that could make a packed bed of spherical particles having particle size distribution. In addition, the influence of the particle shape of the actual powder on the packing density was quantitatively analyzed. The predicted packing densities corresponded well to the actual data.

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전해부상에서 전압과 극판 재질에 따른 미세기포의 크기 특성 (Size Characteristics of Micro-bubbles According to Applied Voltage and Electrode materials)

  • 박용호;한무영
    • 상하수도학회지
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    • 제16권6호
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    • pp.663-669
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    • 2002
  • Electro-flotation (EF) has shown advantages, such as a high removal efficiency and easy control of bubble generation, over dissolved air flotation. However, the fundamental characteristics of the process have not been investigated in detail. According to recent modeling results from trajectory analysis, the size of the bubble is one of the most important factors that affect the efficiency of collision between bubble and particle. In this paper, the size characteristics of bubbles generated from EF under various conditions are measured using a new method for bubble size measurement, the Particle Counter Method (PCM). The size of the generated bubbles was found to be constant with respect to applied voltage but to vary with the electrode materials. These results and their implications are discussed.