• Title/Summary/Keyword: Silica particle

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Effects of SiC Particle Size and Inorganic Binder on Heat Insulation of Fumed Silica-based Heat Insulation Plates

  • Jo, Hye Youn;Oh, Su Jung;Kim, Mi Na;Lim, Hyung Mi;Lee, Seung-Ho
    • Journal of the Korean Ceramic Society
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    • v.53 no.4
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    • pp.386-392
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    • 2016
  • Heat insulation plates of fumed silica were prepared by mixing fumed silica, SiC powder and chopped glass fiber by a high speed mixer followed by pressing of the mixture powder in a stainless steel mold of $100{\times}100mm$. Composition of the plates, particle size of SiC, and type of inorganic binder were varied for observation of their contribution to heat insulation of the plate. The plate was installed on the upper portion of an electric furnace the inside temperature of which was maintained at $400^{\circ}C$ and $600^{\circ}C$, for investigation of heat transfer through the plate from inside of the electric furnace to outside atmosphere. Surface temperatures were measured in real time using a thermographic camera. The particle size of SiC was varied in the range of $1.3{\sim}17.5{\mu}m$ and the insulation was found to be most excellent when SiC of $2.2{\mu}m$ was incorporated. When the size of SiC was smaller or larger than $2.2{\mu}m$, the heat insulation effect was decreased. Inorganic binders of alkali silicate and phosphate were tested and the phosphate was found to maintain the heat insulation property while increasing mechanical properties.

Evaluation of Point-Of-Use (POU) Filters Performance in Chemical Mechanical Polishing Slurry Supply System (슬러리 공급 시스템을 이용한 화학적 기계적 연마 공정에서의 POU 필터의 성능 평가)

  • Jang, Sunjae;Kim, Hojoong;Jin, Hongi;Nam, Miyeon;Kulkarni, Atul;Kim, Taesung
    • Particle and aerosol research
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    • v.9 no.4
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    • pp.261-269
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    • 2013
  • The chemical mechanical polishing (CMP) process is widely used in semiconductor manufacturing process for planarization of various materials and structures. Point-of-use (POU) filters are used in most of the CMP processes in order to reduce the unwanted micro-scratches which may result in defects. The performance of the POU filter is depends on type and size of the abrasives used during cleaning process. For this reason, there is a need to evaluate POU filters for their filtration efficiency (FE) with different types of abrasives. In this study, we developed filter test system to evaluate the FE of POU using ceria and silica abrasives (slurry). The POU filter is roll type capsule filter with retention size of 0.2 ${\mu}m$. Two POU filters of different make are evaluated for FE. We observed that both POU filters show similar filtration efficiency for silica and ceria slurry. Results reveal that the ceria slurry and the colloidal silica particle are removed not only by mechanical way but also hydrodynamic and electrostatic interaction way.

An Experimental Study on the Heat and Mass Transfer of Adsorption Chiller (흡착식 냉동기의 열 및 물질전달에 관한 실험적 연구)

  • Kwon Oh-Kyung;Yun Jae-Ho;Joo Young-Ju;Kim Yong-Chan;Kim Joung-Ha
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.17 no.8
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    • pp.746-753
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    • 2005
  • Adsorption chillers have been receiving considerable attentions as they are energy-saving and environmentally benign systems. In order to evaluate adsorption rates, experiments were performed in the batch type adsorption apparatus. Three types of silica gels were investigated under an assortment of experimental conditions that are representatives of the actual operating environments in the adsorber of adsorption chillers. Experimental results revealed the effects of silica gel particle size, bed temperature, and fin pitch of fin tube on the adsorption rate. The $0.25\~1.18mm$ particle size of silica gel with high adsorption rate was selected as a suitable adsorbent. The measured adsorption rate became bigger with decreasing particle size. From the comparison of adsorption rate, it is found that the fin tube has about $21\%$ higher value than that of the bare tube. The effect of heat and mass flux is found to be more significant in the fin tube than in the bare tube.

Effect of Water Volume and Relaxation Time in the Design of Nano Shock Absorbing Damper Using Silica Particle (실리카 분말을 이용한 나노 충격완화 장치의 설계에서 작동 유체 영향과 복원 시간에 대한 연구)

  • 문병영;김병수
    • Journal of the Korean Ceramic Society
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    • v.40 no.3
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    • pp.286-292
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    • 2003
  • In this study, new shock absorbing system was proposed using silica gel particles according to the nano-technology. For the design and real application of the proposed damper, an experimental investigations are carried out using colloidal damper, which is statically loaded. The porous matrix is composed from silica gel(labyrinth architecture), coated by organo-silicones substances, in order to achieve a hydrophobic surface. Water is considered as associated lyophobic liquid. Reversible colloidal damper static test rig and the measuring technique of the static hysteresis were described. Iufluence of the water volume and particle diameters upon the reversible colloidal damper hysteresis was investigated. Also, influence of the relaxation time on the hysteresis of the damper was investigated. As a result, the proposed new shock absorbing damper is proved as an effective one, which can be replaced for the conventional hydraulic damper.

Separation of Hydrogen-Nitrogen Gas Mixture by PTMSP-Silica-PEI Composite Membranes (PTMSP-Silica-PEI 복합막에 의한 수소-질소 혼합기체 분리)

  • Lee Hyun-Kyung;Choi Youn-Jung
    • Membrane Journal
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    • v.14 no.4
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    • pp.304-311
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    • 2004
  • The poly(1-trimethylsilyl-1-propyne) (PTMSP) and silica-filled PTMSP membranes were prepared by casting from a toluene solution on porous polyetherimide (PEI). FT-IR spectrum, GPC and SEM pictures have been taken to characterize the membranes. The particle size of membrane decreases as silica content of the membrane increases from 23 to 60 wt%, and a uniform distribution of the silica is observed. The separation properties of the gas mixture (32 mol% $H_2$/ 68 mol% $N_2$) through the composite membranes were studies as a function of pressure and percentage of silica. Selectivity values of $H_2$/$N_2$ increased as the pressure of permeation cell and silica content of the membrane increased. The real separation factor($\alpha$), head separation factor($\beta$), and tail separation factor((equation omitted)) of PTMSP-PEI composite membrane were 2.28, 1.58, and 1.44 respectively at $\Delta$P 30 psi and $25^{\circ}C$. $\alpha$, $\beta$, and (equation omitted) of PTMSP-Silica-PEI composite membrane for 60 wt% silica were 3.34, 1.95, 1.72 at $\Delta$P 30 psi and $25^{\circ}C$.

Fabrication of Low Loss Silica Slab Waveguide by Flame Hydrolysis Deposition (FHD 공정에 의한 저손실 실리카 슬랩 도파로 형성)

  • 심재기;김태홍;신장욱;박상호;김덕준;성희경
    • Journal of the Korean Ceramic Society
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    • v.37 no.6
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    • pp.524-529
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    • 2000
  • Silica slab wavegudie was fabricated on Si substrates by FHD for planar optical passive devices. The slab waveguide consists of lower clad and core layers, where core layer index is controlled by GeO2 addition. Doping of GeO2 in silica is difficult because of the low deposition density due to nonspherical particle generation in FHD process. Silica core particles deposited at various conditions such as flame temperature and substrate scanning were analyzed by SEM and TEM. As the flame temperature increased, the surface roughness of the core layer was decreased up to 3.6 nm after consolidation. Index difference and thickness of core of slab waveguide were 0.3%, 8$\mu\textrm{m}$ respectively. Measured optical loss at TE mode was <0.04 dB/cm at 1.3$\mu\textrm{m}$ and <0.06 dB/cm at 1.55$\mu\textrm{m}$.

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Effect of Silica Addition on Phase Transformation Characteristics of Heat-Treated Combustion-Synthesized TiO2 Nanoparticles (실리카가 첨가된 연소합성 TiO2 나노입자의 열처리에 따른 상변환 특성)

  • Kim, Min-Su;Lee, Gyo-Woo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.33 no.3
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    • pp.186-193
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    • 2009
  • In this article, the effect of silica addition on the phase transformation characteristics of $TiO_2$ nanoparticles synthesized by using an $O_2$-enriched coflow, hydrogen, diffusion flame was investigated. TTIP(titanium tetra-isopropoxide) and TEOS(tetraethyl-orthosilicate) were used as precursors for $TiO_2$ and $SiO_2$ nanoparticles, respectively. Based on the results from TEM and XRD analysis, it is believed that the silica addition on the flame synthesis of $TiO_2$ nanoparticles reduces the particle size distribution and raises the temperature of the phase transition from anatase to rutile. But the reduced sizes of the synthesized particles due to the silica addition made the sintering and phase transformation of particles more easily.

STUDIES FOR THE CHARACTER OF THE POROUS SILICA CONTAINING THE NANO-SIZED TIO$_2$, PARTICLE IN THE PORE.

  • Jhun, Hyun-pyo;Kong, Woo-sik;Lee, Kyoung-chul
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.24 no.3
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    • pp.59-64
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    • 1998
  • In order to lower porosity of the porous silica, titanium alkoxide solution was filled in the pore of silica in the heating-vacuum condition. The specific surface area of modified samples was decreased effectively from 900 m$^2$/g to 100 m$^2$/g. (The aggregation phenomena in modified samples were improved fairly.) Samples were heated at 600 , and then the titanium alkoxide in the pore was decomposed completely to titanium oxide from TGA-DTA measurement. From SEM result, it was evident that titanium oxide did not coat the surface of the silica. The modified samples were analyzed using SEM, DTA-TGA, BET, and UV-visible spectrometer.

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Tribological and Optical Characteristics of Silica Coating for Anti-reflection Coating of Solar Cell (태양전지의 반사방지막을 위한 Silica 코팅의 트라이볼로지 및 광학적 특성 평가)

  • Kim, Hae-Jin;Kim, Dae-Eun
    • Transactions of the Society of Information Storage Systems
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    • v.6 no.2
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    • pp.68-73
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    • 2010
  • The interest in acquiring high efficiency solar cells has been steadily increasing due to various advantages such as low-cost installation, pollution free and everlasting energy generation. In order to raise the cell efficiency, there has been a lot of effort to develop effective anti-reflection coatings. In this work, the main objective was to investigate the effects of particle size and annealing temperature of silica anti-reflection coatings to maximize the cell efficiency as well as reliability. It was shown that the light transmittance could be increased by a few percent over a certain range of wavelength using the silica coating. Also, the tribological properties of the coating could be improved through the annealing process, which led to better reliability of the coating.