• Title/Summary/Keyword: particle size effect

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Influence of Particle Size Distribution on Green and Sintered Properties of Fe-Cr-Mo Prealloy Powder (Fe-Cr-Mo 합금 분말의 성형 및 소결특성에 미치는 입도분포 영향)

  • Kim, Ki-Bong;Yang, Sangsun;Kim, Yong-Jin;Park, Yong-Ho
    • Journal of Powder Materials
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    • v.20 no.1
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    • pp.7-12
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    • 2013
  • The effect of particle size distribution on green and sintered properties of Fe-Cr-Mo prealloy powder was investigated in this study. For the study, prealloyed Fe-Cr-Mo powders with different particle sizes were mixed as various ratios and cold compacted at various pressure and sintered at $1250^{\circ}C$ for 30 min, $90%N_2+10%H_2$ atmosphere in the continuous sintering furnace. The results shows that the powders with large particle size distribution have high compressibility and low ejection force. However the green strength are much less than those with small particle size distribution. Tensile prperties of the sintered specimes with large particles size also have high strength and elongation.

Effect of Inflow Rate of Raw Material Solution on the Fabrication of Nano-Sized Cobalt Oxide Powder by Spray Pyrolysis Process

  • Kim, Dong Hee;Yu, Jae Keun
    • Korean Journal of Materials Research
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    • v.26 no.11
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    • pp.662-669
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    • 2016
  • In order to identify changes in the nature of the particles due to changes in the inflow rate of the raw material solution, the present study was intended to prepare nano-sized cobalt oxide ($Co_3O_4$) powder with an average particle size of 50 nm or less by spray pyrolysis reaction using raw cobalt chloride solution. As the inflow rate of the raw material solution increased, droplets formed by the pyrolysis reaction showed more divided form and the particle size distribution was more uneven. As the inflow rate of the solution increased from 2 to 10 ml/min, the average particle size of the formed particles increased from about 25 nm to 40 nm, while the average particle size did not show significant changes when the inflow rate increased from 10 to 50 ml/min. XRD analysis showed that the intensity of the XRD peaks increased remarkably when the inflow rate of the solution increased from 2 to 10 ml/min. On the other hand, the peak intensity stayed almost constant when the inflow rate increased from 10 to 50 ml/min. With the increase in the inflow rate from 2 to 10 ml/min, the specific surface area of the particles decreased by approximately 20 %. On the contrary, the specific surface area stayed constant when the inflow rate increased from 10 to 50 ml/min.

Particle Size Distribution, Drug Loading Capacity and Release Profiles of Solid Lipid Nanoparticles of Phenylpropionic Acids (페닐프로피온산계 해열진통제 고형지질나노입자의 입도분포와 약물봉입 및 용출특성)

  • Kim, Yoon-Sun;Kim, Kil-Soo
    • Journal of Pharmaceutical Investigation
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    • v.28 no.4
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    • pp.249-255
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    • 1998
  • Solid Lipid Nanoparticle(SLN), one of the colloidal carrier systems, has many advantages such as good biocompatibility, low toxicity and stability. In this paper, the effects of drug lipophilicity and surfactant on the drug loading capacity, particle size and drug release profile were examined. SLNs were prepared by homogenization of melted lipid dispersed in an aqueous surfactant solution. Ketoprofen, ibuprofen and pranoprofen were used as model drugs and tweens and poloxamers were tested for the effect of surfactant. Mean particle size of prepared SLNs was ranged from 100 to 150nm. The drug loading capacity was improved with the most lipophilic drug and low concentration of surfactant. Particle size and polydispersity of SLNs were changed according to the used lipid and surfactant. The rates of drug release were controlled by the loading drug and surfactant concentration. SLN system with effective drug loading efficiency and proper particle size for the intravenous or oral formulation can be prepared by selecting optimum drug and surfactant.

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Preparation of Ultrafine Silica Particle by Pyrolysis in the Gas Phase (기상열분해법에 의한 초미립 실리카분말 제조)

  • Jang, Hee Dong;Yoon, Ho Sung
    • Applied Chemistry for Engineering
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    • v.8 no.6
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    • pp.901-906
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    • 1997
  • Ultrafine silicon dioxide($SiO_2$) powder was prepared from tetraethylorthosilicate(TEOS) by the gas-phase reaction. The effects of reaction temperature, flow rate of gas, TEOS concentration, and preheating temperature of reactants on the particle size were investigated. As the reaction temperature increased, average particle size of the silicone dioxide powder became smaller. Smaller particles were also obtained with decreasing the residence time of reactants in the reaction zone. Larger particles having narrow size distribution were produced with the high concentrations of the reactants. The effect of the preheating temperature was not considerable on the average particle size. The range of average particle size was from 30 nm to 58 nm depending on experimental conditions.

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Amorphous Ultrafine Particle Preparation for Improvement of Bioabailability of Insolube Drugs: Effect of Co-Grinding of UDCA with SLS (난용성 의약품의 생체이용률 증진을 위한 무정형 초미립자의 조제 : UDCA와 SLS의 혼합분쇄 효과)

  • 정한영;곽성신;김현일;최우식
    • YAKHAK HOEJI
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    • v.46 no.2
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    • pp.102-107
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    • 2002
  • The particle size of medicinal materials is an important physical property which affects the pharmaceutical behaviors such as dissolution, chemical stability, compressibility and bioavailability of solid dosage forms. The size reduction of raw pharmaceutical powder is needed to formulize insoluble drugs or slightly soluble drugs and to improve the pharmaceutical properties such as the solubility, the pharmaceutical mixing and the dispersion. The objective of the present study is to evaluate the grinding characteristics of ursodeoxycholic acid(UDCA) as a model of insoluble drugs. The effects of the grinding time and the amount of additive on particle size distribution of ground UDCA were investigated. Grinding of insoluble drug, UDCA and a series of dry co-grinding experiments of UDCA with sodium lauryl sulfate(SLS) as an additive were carried out using a planetary ball mill. It was measured that the median diameter and the particle size distribution of ground products with grinding UDCA and additive SLS by Mastersizer. As a result of co-grinding of UDCA and SLS, the particle size of co-grinding products was decreased more than single grinding one. However, it was observed that co-grinding products were reaggregated to larger particles after 120 min.

Effects of Microstructure Morphology on Fluid Flow Characteristics of A356 Commercial Alloy in Semi-Solid Slurry (반고상 A356 합금 슬러리의 미세조직에 따른 유동특성에 관한 연구)

  • Kim, Jae-Min;Lee, Seung-Hoon;Hong, C.P.
    • Journal of Korea Foundry Society
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    • v.25 no.6
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    • pp.240-248
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    • 2005
  • The rheocasting characteristics are strongly influenced by the microstructural morphology such as particle size, form factor and contiguity. In this study, the effect of structural morphology on fluid flow characteristics of A356 semi-solid alloy was investigated with a vacuum suction fluidity test. Semi-solid metal slurry was made by the mechanical stirring, the liquidus casting, and H-NCM to be analysed. H-NCM could obtain uniform and fine globular microstructures of 0.9 form factor and 55 ${\mu}m$ particle size. Inoculation was found to be effective for reducing particle size, however, for H-NCM it should be avoided due to the cause of increasing contiguity. The fluidity test indicated that the non-stirring method had higher fluidity and smaller liquid segregation in the same solid faction of 0.4 than the stirring method, for smaller particle size and higher form factor. It was observed that liquid segregation decreased as the particle size is smaller and form factor is higher. The results of die-casting experiment were a good agreement with those of fluidity test.

Effect of Initial Particle Size Distribution of (K0.5Na0.5)NbO3 Powders on Microstructure of Their Sintered Ceramics ((K0.5Na0.5)NbO3 세라믹스의 초기 분말 입도 분포가 소결체의 미세구조에 미치는 영향)

  • Yoo, Il-Ryeol;Choi, Seong-Hui;Cho, Kyung-Hoon
    • Journal of the Korean Society for Heat Treatment
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    • v.35 no.2
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    • pp.57-65
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    • 2022
  • In this study, the effect of the initial particle size distribution (PSD) of (K0.5Na0.5)NbO3 powders on the microstructure of sintered ceramics was investigated. (K0.5Na0.5)NbO3 powders with uni-, bi-, tri-, and quad-modal PSDs were obtained through a planetary ball-mill. For the specimens sintered at 1080℃, the growth of abnormal grains was promoted from the powders exhibiting quad- and tri-modal PSDs with a high content of large particles, resulting in a microstructure in which huge abnormal grains were predominant. However, as the number of peaks in PSD and the overall particle size decreased, the abnormal grain growth was suppressed and the grain growth of small particles started, resulting in a microstructure with a uniform grain size. For the specimens sintered at 1100℃, huge abnormal grains were not observed due to the decrease in the critical driving force for 2D nucleation even when powders with quad- and tri-modal PSDs were used. It was confirmed that when powder with unimodal PSD was used, a uniform microstructure that was not significantly affected by the sintering temperature could be obtained. The results of this study demonstrate that the microstructure of (K0.5Na0.5)NbO3-based ceramics can be controlled by controlling the particle size of the initial powder.

An Experimental Study on Enhancement of the Filter Efficiency by the Image Effect of Charged Particle (대전된 입자의 영상효과에 의한 필터효율 향상에 관한 실험적 연구)

  • Lee, Chang-Sun;Jeong, Hae-Young;Kim, Sang-Soo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.24 no.6
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    • pp.760-768
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    • 2000
  • Filter efficiency of electrically charged particle in uncharged fibrous filter was measured. In previous studies, the effect of charged particle on filter efficiency was investigated but there was difficulty in measuring of image effect that is appeared at the charged small particle. We could easily measure the image effect with charging small particles by photoelectric charging. The spark discharge aerosol generator and a differential mobility analyzer (DMA) were used to generate sub-micron monodisperse particles (${\leq}200$ nm). The generated particles were charged in photoelectric charging process using ultraviolet lamp and electric field. The filter efficiency of the charged particles, classified by another DMA, was measured in filter tester using a condensation nucleus counter (CNC) as function of particle diameter, particle charge and airflow velocity. It is shown that the filter efficiency increases with increasing charge number of the particle and is affected by particle size and flow velocity. Single fiber filter efficiency mainly depends on image force parameter and peclet number. The peclet number was not considered at previous other papers. We propose a modi fied experimental correlation as function of image force parameter and peclet number.

Effect of Particle Sizes of Polymer Binders for Pigment Inks on Touch of Fabrics (안료 잉크용 바인더의 입자 크기가 직물의 태에 미치는 영향)

  • Park, Seongmin;Han, Minwoo;Jeong, Euigyung
    • Textile Coloration and Finishing
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    • v.32 no.4
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    • pp.226-231
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    • 2020
  • This study investigated effect of particle sizes of polymer binders for digital textile printing(DTP) pigment inks on touch of fabrics. The polymer binders were synthesized via miniemulsion polymerization of methyl methacrylate(MMA), butyl acrylate(BA), N-ethylolacrylamide(NEA) and methacrylic acid(MAA). The prepared binders were applied to black pigment inks and those black pigment inks were used to dye cotton fabrics. Then, color strength, rubbing fastness, stiffness, surface and bending properties of the dyed fabrics were investigated. Depending on the particle size of the polymer binder used, color strength, friction fastness, stiffness, surface and bending properties change. Generally, the larger the particle size of the polymer binder, the softer properties.

Computer Simulation for Microstructure Development in Porous Sintered Compacts (다공질 소결체의 조직형성에 관한 컴퓨터 시뮬레이션)

  • Shin, Soon-Ki;Matsubara, Hideaki
    • Journal of the Korean Ceramic Society
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    • v.43 no.4 s.287
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    • pp.213-219
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    • 2006
  • A Monte Carlo simulation based on Potts model in a three dimensional lattice was studied to analyze and design microstructures in porous sintered compacts such as porosity, pore size, grain (particle) size and contiguity of grains. The effect of surface energy of particles and the content of additional fine particles to coarse particles on microstructure development were examined to obtain fundamentals for material design in porous materials. It has been found that the larger surface energy enhances sintering (necking) of particles and increases contiguity and surface energy does not change pore size and grain size. The addition of fine particles also enhances sintering of particles and increases contiguity, but it has an effect on increment of pore size and grain size. Such a simulation technique can give us important information or wisdom for design of porous materials, e.g., material system with high surface energy and fine particle audition are available for higher strength and larger porosity in porous sintered compacts with applications in an automobile.