• Title/Summary/Keyword: Submicron particle

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A Case Study on Sintering Characteristics of Yttria Stabilized Zirconia Powder Prepared by Two-Fluid Spray Drying

  • Choi, Jin Sam;Kong, Young-Min
    • Journal of the Korean Ceramic Society
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    • v.53 no.3
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    • pp.332-337
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    • 2016
  • As a case study on yttria stabilized zirconia ceramics, the sintering characteristics of submicron powders and the granulation prepared by two-fluid spray drying of submicron particles were investigated. As-received powders of yttria stabilized zirconia particles were reduced to a uniform size of less than about 200 nm by repeated milling. Granulation size obtained by the two-fluid spray drying was affected by the organic matter and the primary particle size. Sintering behavior such as porosity, water absorption ratio, density, and transparency was influenced by processing conditions of the powder, and the discontinuous interfaces in a green body were reduced.

Preparationof High Purity, Submicron BaTiO3 Powder Prepared by Hydrothermal Reaction (수열반응에 의한 고순도 극미립자 BaTiO3 분말합성)

  • 김경용;김윤호;손용배
    • Journal of the Korean Ceramic Society
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    • v.26 no.4
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    • pp.493-498
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    • 1989
  • High purity, submicron BaTiO3 powder was prepared by a hydrothermal technique using Ba(OH)2.8H2O, TiCl4 and NH4OH as starting raw materials. The submicron BaTiO3 powder was synthesized at 130~23$0^{\circ}C$ for 2.5h to yield highly crystalline particles with a narrow particle distribution. The mole ratio of Ba(OH)2.8H2O/TiO(OH)2 was 1.5. It is possible to obtain BaTiO3 with Ba : Ti=1.00$\pm$0/01. The samples densified well at 13$25^{\circ}C$, showing a uniform and fine grain structure. The grain size ranged between 0.3 and 0.5${\mu}{\textrm}{m}$. The products obtained by hydrothermal treatment at various temperatures from 130 to 23$0^{\circ}C$ were characterized by XRD, DTA, BET and SEM etc.

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An Experiment on Particle Collection and Gas Removal in a 2-Stage Electrostatic Wet Scrubber (2단 정전식 세정집진기의 집진 및 가스제거 특성)

  • Yeo, Kuk-Hyun;Yoo, Kyung-Hoon;Son, Seung-Woo;Kim, Yoon-Shin
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.18 no.9
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    • pp.745-752
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    • 2006
  • DOS and NaCl aerosol particles were used to determine collection efficiencies of a 2-stage electrostatic wet scrubber with respect to particle size. The DOS and NaCl aerosols have geometric mean diameters of 0.1-3.0 urn, geometric standard deviations of $1.1{\sim}1.8$ and total number concentrations of $450{\sim}2,400\;particles/cm^3$. The tested operating variables for the electrostatic wet scrubber included air velocity and water injection rate. It was shown from the experimental results that particle collection efficiencies increased in the submicron particle size range when different polarities were applied on the water nozzle and corona wire, respectively. This increase in the collection efficiency is attributed to strong electrostatic attraction between the negative water droplets and positive submicron particles. The collection efficiencies also increased when water injection rate was increased or air velocity was decreased. Meanwhile, the pressure drop across the wet scrubber decreased by 90% compared with the existing mechanical wet scrubber. Finally, ammonia gas was used to determine gas removal efficiencies. It was observed that the gas removal efficiencies increased when the air velocity was decreased or the water injection rate was increased.

Theoretical Study on Magnetic Field Application for Fine Particle Capture

  • Huang, Shan;Park, Haewoo;Jo, Youngmin
    • Particle and aerosol research
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    • v.10 no.2
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    • pp.45-51
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    • 2014
  • Fine particle capture is facing a challenge since traditional filtration which relies on the combination of impaction, interception, diffusion has a limited efficiency for fine particle capture particularly in size from 0.1 to $0.5{\mu}m$. This paper reviewed the collection efficiency of above mechanisms, as well as magnetic mechanisms for ferromagnetic particles, and mainly studied the influencing factors of magnetic filtration. Filtration velocity, magnetic field intensity and fiber size were found to be the most important parameters for magnetic filtration.

Development of real-time nanoscale contaminant particle characteristics diagnosis system in vacuum condition (진공공간 내 나노급 오염입자의 실시간 진단시스템 개발)

  • Kang, Sang-Woo;Kim, Taesung
    • Vacuum Magazine
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    • v.2 no.3
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    • pp.11-15
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    • 2015
  • Particle characteristics diagnosis system (PCDS) was developed to measure submicron particle characteristics by modulation of particle beam mass spectrometry (PBMS) with scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). It is possible to measure the particle size distribution in real-time, and the shape, composition can be measured in sequence keeping vacuum condition. Apparatus was calibrated by measuring the size classified NaCl particle which generated at atmospheric pressure. After the calibration, particles were sampled from the exhaust line of plasma enhanced chemical vapor deposition (PECVD) process and measured. Result confirms that PCDS is capable for analyzing particles in vacuum condition.

Preparation of Spherical Nickel Powder by Hydrothemal Process (수열합성법을 이용한 구형 니켈분말 제조)

  • 원창환;배장호;이종현;김병범
    • Journal of Powder Materials
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    • v.11 no.3
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    • pp.217-223
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    • 2004
  • Submicron nickel powders were prepared from aqueous solution under hydrothermal condition. The experimental conditions including the types of protective agents, concentration of the solution and the pH were studied in detail. Starting concentration of nickel ion is a dominant factor affecting particle size. It was shown that the subsequent addition of Poly Vinyl Pyrrolidone(PVP) and Sodium Dodecyle Sulfate(SDS) can help to disperse the nickel powder. X-ray diffraction and SEM were employed to characterize the products.

Studies on the Chemical Compositions and Distributions of Ambient Sumicron Aerosols (Submicron 부유분진의 화학적 조성 및 분포에 관한 연구)

  • 황인조;김동술
    • Journal of Korean Society for Atmospheric Environment
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    • v.14 no.1
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    • pp.11-23
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    • 1998
  • The purpose of this study was to survey chemical distribution of inorganic elements and ions in the submicron particles, to characterize qualitatively emitting sources by factor analysis, and finally to reveal existing patterns in terms of chemical compounds by a stepwise multiple regression analysis. Total of 141 samples were collected by a cascade impactor from 1989 to1996. Fifteen chemical species (Al, Ba, Cd, K, Pb, Cu, Fe, Ni, $Cl^-, NO_3^-, SO_4^{2-}, K^+, Mg^{2+}, Ca^{2+}, and Na^+$) were characterized by AAS and IC. The study showed that average seasonal levels of submicron particulate matters $(d_p<0.43 \mum)$ were 18.7 $\mug/m^3$ in spring, 15.5 $\mug/m^3$ in summer, 15.7 $\mug/m^3$ in fall, and 24.5 $\mug/m^3$ in winter, respectively. All of the anion concentrations in the particle were highest in the winter season. By applying a factor analysis, 5 source patterns were qualitatively obtained, such as sulfate related source, nitrate related source, oil burning source, calcium related source, and coal combustion source. Finally, when applying a stepwise multiple regression analysis, the results clearly showed that $Na^+ and Ca^{2+}, K^+ and Ca^{2+}, NO_3^-$ and relative humidity, $Cl^-$ and ambient temperature, $Ca^{2+} and Cl^-, Mg^{2+} and SO_4^{2-}, Na^+ and NO_3^-, and Ca^{2+} and NO_3^-$, respectively, are negatively contributed to each other. As a result of those statistical analysis, we could suggest that some chemical compounds in the submicron particles such as$NaNO_3, MgSO_4, Ca(NO_3)_2, and CaCl_2$ may not exist on the filter as final composing products; however, other compounds may possibly exist in the form of $Mg(NO_3)_2, CaSO_4, Na_2SO_4, K_2SO_4, MgCl_2, NaCl, and KCl$. Thus, it must be necessary to identify differences between the results of above statistical analysis and of the real world by laboratory experiments.

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Study on improvement of submicron particle collection performance in 2-stage parallel-plate electrostatic precipitators (2단 평행판 전기집진기의 서브마이크론입자 집진성능 개선 연구)

  • Yoo, K.H.;Oh, M.D.;Lee, J.S.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.9 no.3
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    • pp.323-332
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    • 1997
  • It was reported by some researchers that two-stage parallel-plate ESPs, commonly called electronic air cleaners, show decreasing behavior of collection efficiency as particle size decreases below about $0.03{\mu}m$. This phenomenon is attributed to partial particle charging characteristics, where some of incoming particles are not charged in the charging cell of 2-stage parallel-plate ESP. One way to improve the decreasing collection efficieny in that particle size range is to enforce particle charging quantity in the charging cell. In the present study, in order to do this a 2-wire series-type charging cell modified from a 1-wire normal-type one was suggested and investigated theoretically and experimentally concerning improvement of the collection efficiency. It was confirmed from the experimental and theoretical works that the collection efficiency was apparently improved.

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Development and Evaluation of Hy-SMPS (Hy-SMPS의 개발 및 성능평가)

  • Lee, Hong-Ku;Eun, Hee-Ram;Lee, Gun-Ho;Ahn, Kang-Ho
    • Particle and aerosol research
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    • v.11 no.2
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    • pp.57-61
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    • 2015
  • Atmospheric nano-particles along the altitude is one of the main factors causing severe weather phenomena. It is a challenge to find the precise particle size distribution. One useful instrument includes a scanning mobility particle sizer (SMPS). This measures the size distribution of submicron aerosols. The SMPS consists of a condensation particle counter (CPC), differential mobility analyzer (DMA), high voltage power supplier (HVPS), and neutralizer. Due to the many components, it is difficult to install a commercial SMPS into a tethered balloon package system (Eun, 2011). In this study, we customized a SMPS for the tethered balloon package system called Hy-SMPS. It is portable, compact in structure, and evaluated by TSI SMPS using mono and poly-dispersed particles.

Packing of Alumina Particles in 3D Preform of Mullite Fiber by Slurry Pressure-Infiltration (슬러리 가압함침에 의한 3D Mullite 섬유 Preform의 알루미나 입자 충전)

  • Sim, Soo-Man
    • Journal of the Korean Ceramic Society
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    • v.50 no.6
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    • pp.528-532
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    • 2013
  • Well-dispersed slurries of submicron-sized alumina powders were pressure-infiltrated in 3D preforms of mullite fibers and the effects of the particle size and infiltration pressure on the particle packing characteristics were investigated. Infiltration without pressure showed that the packing density increased as the particle size decreased due to the reduction of the friction between the particles and the fibers. The infiltrated preforms contained large pores in the large voids between the fiber tows and small pores in the narrow voids between the individual fibers. Pressure infiltration resulted in a packing density of 77% regardless of the particle size or the infiltration pressure(210 ~ 620 kPa). Pressure infiltration shortened the infiltration time and eliminated the large pores in preforms infiltrated with the slurries of smaller particles. The slurry pressure-infiltration process is thus an efficient method for the packing of matrix materials in various preforms.