• Title, Summary, Keyword: particles

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The growth effect of agglomerated and nonagglomerated particles in Condensation Nuclei Counter (CNC) (응집입자와 비응집 입자의 CNC 내에서 응축성장에 관한 실험적 연구)

  • Kim, Y.W.;Moon, H.W.;Yoon, J.U.;Ahn, K.H.
    • Proceedings of the KSME Conference
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    • pp.579-584
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    • 2001
  • Agglomerated and nonagglomerated SiO2 particles are synthesized in furnace by the electrohydrodynamic spraying method and the vapor feeding method for the test particle generator this study. These polydispersed particles are classified with DMA to extract equal mobility particles. Then these particles are introduced into CNC (Condensation Nuclei Counter) to see the pulse height using Multi-channel Analyzer. The response characteristics of these two kinds of particles in CNCs (TSI CNC 3022 and 3025A) have been studied as a function of particle size using mono disperse particles classified by DMA. The results show that the higher drag resistance particles, so called agglomerated particles have generated a lower CNC pulse height than the spherical particles for these two different CNCs, which means the nonagglomerated particles may start to grow larger than the agglomerated particles.

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Polymers and Nanosized Particles: A Happy Marriage?

  • Wegner, Gerhard
    • Proceedings of the Polymer Society of Korea Conference
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    • pp.7-8
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    • 2006
  • Interest in "nanotechnology" has triggered the question whether new materials can be obtained blending nanosized particles with polymers. This contribution considers modification of polymer properties by nanoscale particles, stabilization of polymer properties by nanoscale particles, stabilization of nanoscale particles against Ostwald-ripening and agglomeration, synthesis of nanoscale particles assisted by polymers and effects of such particles on polymerization mechanisms.

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Porous Silica Particles As Chromatographic Separation Media: A Review

  • Cheong, Won Jo
    • Bulletin of the Korean Chemical Society
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    • v.35 no.12
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    • pp.3465-3474
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    • 2014
  • Porous silica particles are the most prevailing raw material for stationary phases of liquid chromatography. During a long period of time, various methodologies for production of porous silica particles have been proposed, such as crashing and sieving of xerogel, traditional dry or wet process preparation of conventional spherical particles, preparation of hierarchical mesoporous particles by template-mediated pore formation, repeated formation of a thin layer of porous silica upon nonporous silica core (core-shell particles), and formation of specific silica monolith followed by grinding and calcination. Recent developments and applications of useful porous silica particles will be covered in this review. Discussion on sub-$3{\mu}m$ silica particles including nonporous silica particles, carbon or metal oxide clad silica particles, and molecularly imprinted silica particles, will also be included. Next, the individual preparation methods and their feasibilities will be collectively and critically compared and evaluated, being followed by conclusive remarks and future perspectives.

The Numerical Simulation on the Wet Deposition of Particles (입자상 물질의 습성 침적에 관한 수치 모의)

  • Kim, Yu-Geun;Lee, Hwa-Un;Hong, Jeong-Hye
    • Journal of Korean Society for Atmospheric Environment
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    • v.14 no.5
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    • pp.433-442
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    • 1998
  • The removal procedure of particles in the atmosphere was simulated in the saturated and dry conditions to know the effect of the saturated atmosphere on the size distributions of particles. The particles were divided into 5 ranges, 0.0mm, 0.0∼0.65mm, 0.65∼2mm, 2∼10mm and more than 10mm, and the gases were classified into the smallest range for calculation. At the dry condition, particles grew only by the collision -coalescence and were removed by gravitation. The particles in the range of 2.0∼10mm fell mostly at the 30 km distance from the pollutant source because of gravitation. The particles larger than 10 pm were removed at the 10 km distance from the pollutant source because of their gravity. But the particles larger than 10pm appeared again at more than 30km distance. It is considered that they have been grown during the smaller particles had been advected and diffused at that distance, and it needed about 1 hour from the moment of release. At the saturated condition, particles grew by both the collision-coalescence and condensation. The model showed that the condensation makes more number of particles larger than 10mm and then the particles were removed due to their large gravity. Only a few particles existed at the range of 0.65∼10mm and larger thats 10mm. It is concluded that the saturated atmosphere is effective on removing PM-10.

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A Study on the Mechanism for the Formation of Partices in electroless Ni Composite Coating(I) (무전해 Ni 복합도금 과정에서 분발의 공석 기구에 대한 연구(I))

  • 이원해;이승평
    • Journal of the Korean institute of surface engineering
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    • v.22 no.2
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    • pp.69-77
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    • 1989
  • Codeposion of inert particles particles in a metallic mateix by electroless plating process involves two phenomena. Firstly, the adsorption of inercles and secondly, the adsorption of inert particles on the cathode. In the present paper the first adsorption phenomenon and in the next paper the second ane are studied in greaterdetail for the Ni-SiCc, Ni-Al2AO3 and Ni-WC systems. Measurements of the Zeta potentials for the SiC and Al2AO3 particles have been in different electrolyte solutions and the ionic species adsorbed on the Particles studied. The addition of sodium acetate, trisodium citrate and sodium phosphinate to nikel sulface sruomotes the zeta potential of SiC and Al2O3 particles, but zeta phosphinate to nickel is more positive than Al2O3 particles although the amount of nickel ion adsorbrd on the Al2O3 particles become greater than that of SiC particles. It is suggested that this is due to adsortion of Na ion onto the surface SiC particles.

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Characterization of Crystal Structure for Nanosized Noble Metal Particles Fabricated by ERC(Evaporation and Rapid Condensation) Method (증기급속응축법 제조 귀금속 나노분말의 결정학적 특성 연구)

  • Yu, Yeon-Tae
    • Korean Journal of Materials Research
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    • v.13 no.5
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    • pp.285-291
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    • 2003
  • The nanosized silver and gold particles are prepared by ERC method in which metal vapors with high temperature is rapidly quenched by coolants such as liquid nitrogen or liquid argon. In order to monitor the crystal structural changes on the internal and the surface of the nanosized noble metal particles, lattice parameter, internal strain and Debye-Waller factor are investigated, and the calculation of X-ray diffraction scattering intensity is performed. The lattice parameters of silver and gold particles agree with those of bulk materials, and crystal internal strain of the metal particles is not changed by rapid cooling. The Debye-Waller factor of gold particles is increased with decreasing particle size because of the surface softening phenomenon of nanosized particles, but the crystal structural change on the surface of the particles is not detected from the comparison the calculated X-ray diffraction profile with the experimental profile on gold particles with the particle size of 4 nm.

A Study on Packing of Regular Particles - Preparation of Dense Sintered Silicon Carbide (1) - (규칙입자의 충전 -치밀된 탄화규소 소결체의 제조(제 1 보)-)

  • 문병훈;남건태;최상욱
    • Journal of the Korean Ceramic Society
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    • v.31 no.9
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    • pp.989-994
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    • 1994
  • This study aims at finding the closest packings of regular shape particles such as sphere, circle rod and hexagonal rod type. As the ratio of particle size to container lowered to less than 1/10, the wall effect decreased gradually. The tap density of spherical particles with almost orthorhombic arrangement was 59.5%, while those of circle rod and hexagonal rod type particles were 63.5% and 63.0% respectively. And it was decreased with increasing the aspect ratio of regular particles. The tap density of binary mixtures was larger than that corresponding to the monosized particles packing by about 15%. The tap density of ternary mixtures was larger than that of corresponding to the packing of binary mixtures by about 9%. This work employed the binary mixture of 60% coarse particles and 40% fine particles with size ratio of 1.0 to 1/10 and the ternary mixture of 60% coarse particles, 20% medium and 20% fine particles with size ratio of 1:1/10:1/400 respectively.

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Diameter Control of Carbon Nanotubes Using Surface Modified Fe Nano-Particle Catalysts with APS (APS로 표면 처리한 Fe 나노 입자 촉매를 이용한 CNT의 직경제어)

  • Lee, Sunwoo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.26 no.6
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    • pp.478-481
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    • 2013
  • Diameter controlled carbon nanotubes (CNTs) were grown using surface modified iron nano-particle catalysts with aminpropyltriethoxysilane (APS). Iron nano-particles were synthesized by thermal decomposition of iron pentacarbonyl-oleic acid complex. Subsequently, APS modification was done using the iron nano-particles synthesized. Agglomeration of the iron nano-particles during the CNT growth process was effectively prevented by the surface modification of nano-particles with the APS. APS plays as a linker material between Fe nano-particles and $SiO_2$ substrate resulting in blocking the migration of nano-particles. APS also formed siliceous material covering the iron nano-particles that prevented the agglomeration of iron nano-particles at the early stages of the CNT growth. Therefore we could obtain the diameter controlled CNTs by blocking agglomeration of the iron nano-particles.

Photo-degradation of Phenol and Toluene by Using the TiO2-coated Polyethylene Particles (TiO2가 코팅된 Polyethylene 입자를 이용한 페놀과 톨루엔의 광분해)

  • Kim, Dong-Joo;Choi, Sang-Keun;Cho, Jun-Hyung;Kim, Kyo-Seon
    • Journal of Industrial Technology
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    • v.24 no.B
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    • pp.133-138
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    • 2004
  • The photodegradation of phenol and toluene with the $TiO_2$-coated polyethylene (PE) particles were investigated in the slurry type photocatalytic reactor, changing the $TiO_2$ particle sizes, initial phenol and toluene concentrations, and the oxygen flow rate. The nano-sized $TiO_2$ photocatalyst particles were prepared by the diffusion flame reactor and they were coated onto PE particles by using the hybridization system for the efficient recollection of $TiO_2$-coated particles after photodegradation experiments. The degradation efficiencies of phenol and toluene with the $TiO_2$-coated PE particles were more than 90% after photodegradation of 80 minutes for most cases. The efficiencies of photodegradation with the $TiO_2$-coated PE particles were found to be lower than those by the pure $TiO_2$ particles by 50%, because of the decrease in specific surface area of $TiO_2$ particles in PE particles.

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A Study on Characteristics of Suspended Particles in the River (하천에 함유된 부유입자의 특성에 관한 연구)

  • Moon, Byung-Hyun;Seo, Gyu-Tae;Jang, Deok-Joon
    • Journal of Korean Society on Water Environment
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    • v.21 no.5
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    • pp.500-504
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    • 2005
  • Water samples were collected at 7 sites located along the River Nakdong on 30 occasions. Water qualities, size and fractal dimension ($d_F$) of suspended particles were measured. Laser light scattering method was used to obtain the size and $d_F$ of suspended particles. The average size of particles in this river ranged from $89{\mu}m$ and $169{\mu}m$, which appears to be relatively coarse compared with other rivers worldwide. The average $d_F$ of suspended particles in this study ranged from 1.8 to 1.9. The correlation analysis showed that DO, TN, $NO_3$ and chlorophyll-${\alpha}$ had significant positive relationships with particles size, whereas flow rates and TSS had negative relationships. Interestingly, the factors of which had positive relationships with particles size showed negative relationship with the fractal dimension ($d_F$) of suspended particles. Generally, as the size of particles increased, the fractal dimension of particles decreased which was indicating the shape of the larger particles became more irregular.