• 한국재료학회지
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• 제26권3호
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• pp.136-142
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• 2016

To study the dispersion factors of silica sol prepared from fumed silica powder, we prepared silica sol under an aqueous system using a batch type bead mill. The dispersion properties of silica sol have a close relationship to dispersion factors such as pH, milling time and speed, the size and amount of zirconia beads, the solid content of fumed silica, and the shape and diameter of the milling impellers. Especially, the silica particles in silica sol were found to show dispersion stability on a pH value above 7, due to the electrostatic repulsion between the particles having a high zeta potential value. The shape and diameter of the impellers installed in the bead mill for the dispersion of fumed silica was very important in reducing the particle size of the aggregated silica. The median particle size ($D_{50}$) of silica sol obtained after milling was also optimized according to the variation of the size and amount of the zirconia beads that were used as the grinding medium, and according to the solid content of fumed silica. The dispersion properties of silica sol were investigated using zeta potential, turbiscan, particle size analyzer, and transmission electron microscopy.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.232-233
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• 2006

In recent years the interest in organic/inorganic hybrid materials has increased at a fast rate. Nano organic-inorganic hybrid composites have shown advantages for preparing hard coating layers. Especially, nano hybrid composite has low environmental pollution. It has high transparency, hardness, toughness, thermal dissociation temperature, hydrophobicity by using nano sized inorganic material. There are many ways in which these materials may be synthesized, a typical one being the use of silica and silanes using the sol-gel process. The structure of sol-gel silica evolves as a result of these successive hydrolysis and condensation reactions and the subsequent drying and curing. The sol-gel reactions are catalyzed by acids and produce silica sol solutions. The silica sol grows until they reach a size where a gel transition occurs and a solid-like gel is formed. Colloidal silica(CS)/silane sol solutions were synthesized in variation with parameters such as different acidity and reaction time. In order to understand their physical and chemical properties, sol-gel coating films were fabricated on glass. From all sol-gel solutions, seasoning effect of sol-gel coating layer on glass was observed.

• 멤브레인
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• 제11권3호
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• pp.124-132
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• 2001

고온에서 수소 분리 회수를 목적으로 silica/alumina 복합 막을 합성하였다. 막의 선택 투과 성능을 향상시키기 위해, sol-gel법에 의한 silica 및 alumina층을 중간층으로 도입하고, 그 위에 강제유동 CVD법에 의한 silica를 합성하였다. Sol-gel법에 의해 ${\alpha}$-alumina tube에 합성한 ${\gamma}$-alumina 및 silica 막은 Knudsen 확산 영역의 많은 mesopore를 포함하고 있어서 수소 선택 분리 막으로는 적합하지 못했다. 하지만, sol-gel법에 의해 합성한 silica/${\gamma}$-alumina층에 강제유동 CVD법으로 silica를 합성한 결과, 질소 투과 영역의 세공이 완전히 제거되어, 높은 수소 선택성을 가지는 복합 막이 형성되었다. 그 막은 온도에 따라 수소 투과 속도가 증가하여 $450^{\circ}C$에서 $5.57{\times}10^{-8}molm^2s^LPa^1$의 수소 투과 속도와, 9.52 kJ/mol의 활성화 에너지를 나타냈다. 분자체 효과에 의해 질소 투과가 완전히 배제되고, 수소만 선택적으로 투과되는 silica/alumina 복합막이 성공적으로 합성된다.

• 한국염색가공학회지
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• 제26권4호
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• pp.297-304
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• 2014

In this study, we investigated the relationship between the adsorption property of Methyl violet or Tartrazine dye onto silica sol surface and surface charge density of the sol. The adsorption ratio of Methyl violet dye on silica sol decreased to 74% and 92% for the 68nm and 94nm silica sol, respectively, at dye concentration of $175{\mu}g/m^2$. However, the adsorption ratio of Tartrazine dye on 68nm and 94nm silica sol was about 0% for both of them. The surface charge density is $-0.40C/m^2$, $-0.26C/m^2$ for 68nm and 94nm silica sol, respectively. The amount of Methyl violet dye adsorbed on silica sol increased with an increase of surface charge density of particle at the same concentration of the dye. The adsorbed amount of the silica having high surface charge density is larger at high pH domain. But adsorbed amount of the silica having low surface charge density is larger at low pH domain.

• 한국세라믹학회지
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• 제39권11호
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• pp.1011-1016
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• 2002

Colloidal particles of silica (100 nm in size) were electrostatically dispersed and adsorbed on a glass substrate coated with silica sol or alumina sol. Stability of the suspensions and microstructure of the adsorbed particle layers were discussed in terms of total potential energies between the particles and the substrate. Well-dispersed suspension resulted in a layer with densely packed and regularly arranged particles, whereas less stable suspension resulted in a porous layer with loosely packed and irregularly arranged particles. Despite repulsive interactions between the particles and the substrate coated with silica sol, the observed adsorption can be attributed to chemical bonds formed at the interface between the particle and silica sol. In contrast, the adsorption of the particles on the substrate coated with alumina sol formed a layer with strongly adhered and densely packed particles, due to large attractive interactions between the particles and alumina sol.

• 펄프종이기술
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• 제37권3호
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• pp.33-40
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• 2005

In this study, a nano-colloidal silica sol was applied to control the anti-slip property by spraying on kraft paper. Two kinds of nano-colloidal silica sol which have cationic and anionic charge were applied in kraft paper, and the friction and physical strength properties of kraft paper were investigated. The application of colloidal silica sol on wet web in wet-end process by spraying method was tried to improve the friction property and to avoid the general problems of machine contaminations caused by the scattering of sprayed silica particles in dryer part. The physical properties of sheet were also improved by the application of wet web spraying method, and the optimum conditions of wet web spraying operation were closely related with the conditions of pH and electrical charge of wet web and silica sol.

• 한국전기전자재료학회논문지
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• 제20권1호
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• pp.35-40
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• 2007

The new PEI(poly(epoxy-imide))-nano Silica film has been synthesized via in situ CS sol process, and the chemical bonding and microstructure of nano silica dispersed in resin were examined by FT-IR, TAG and SEM. The dielectric properties of these hybrid films over a given temperature and frequency ranges have been studied in a point of view of stable chemical bonding of nano Silica filler. The results from IR spectra and SEM photograph indicated that PEI-Silica hybrid film prepared with nano CS sol process has been synthesized in uniform and chemical bonding. The decrease property of dielectric constant with CS content, tangent loss consistent of given frequency and temperature has been explained in terms of the chain movement of polymer through chemical bonging and size effect of nano silica. The new PEI-CS sol hybrid film with such stable chemical and dielectric properties was expected to be used as a high functional coating application in ET, IT and electric power products.

• 자원리싸이클링
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• 제18권6호
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• pp.30-37
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• 2009

소디움실리케이트 수용액으로부터 나트륨이온이 제거된 핵생성 산화실리케이트 수용액과 실리케이트 수용액을 pH 10~11로 조절하여 혼합한 다음, $20{\sim}80^{\circ}C$에서 솔-젤 반응하여 실리카 솔 입자를 제조하였다. 이 때 yellow silicomolybdate method를 이용하여 소디움실리케이트와 나트륨이온이 제거된 실리케이트 수용액의 특성과 이들 출발용액으로부터 솔-젤 반응에 의해 제조된 실리카 솔의 입자특성에 대하여 고찰하였다. $SiO_2$를 2 wt% 함유한 소디움실리케이트 수용액은 약 95% 이상의 반응성 실리케이트를 함유하며, 솔-젤 반응에 참여하는 반응성 실리케이트는 전체 실리카 기준 약 50% 정도이다. 반응온도가 증가함에 따라 silanol(Si-OH) 결합구조의 흡수피크 세기는 감소하고, siloxane(Si-O-Si) 결합구조의 흡수피크 세기가 증가하였다. 반응조건별로 제조된 실리카 솔 수용액의 zeta potential은 -40~-60 mV 범위로 분산성이 좋은 상태를 유지하였다. 실리카 솔 입자크기는 5~10 nm로 반응온도 증가에 따라 크기가 약간 감소하였다. 실리카 솔 제조 후, 2차 입자 성장을 위하여 실리케이트 수용액을 재 첨가하였을 경우에 실리카 솔입자 크기가 약 20 nm로 증가하였다.

• 한국전기전자재료학회논문지
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• 제32권3호
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• pp.246-251
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• 2019

A solvent free, highly concentrated silica-acryl monomer hybrid sol was synthesized using aqueous colloidal silica as a precursor. The effects of the silica particle size, type of surface treatment agent employed, and silica content on the formation of the hybrid sol were systematically studied. The optical and physical properties of the coating solution prepared using the hybrid sol were also characterized. The viscosity of the hybrid sol tended to decrease as the particle size of the silica and the molecular weight of the surface treatment agent increased. The PET substrate coated with MPTMS-Mix (mixture, 70 wt%) solution showed the highest surface hardness (6 H) and low surface roughness ($Ra=0.044{\mu}m$), which could be attributed to an increase in packing density caused by the infiltration of small particles into the pores formed between larger particles.

• 한국분말재료학회지
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• 제21권1호
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• pp.21-27
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• 2014

In this study, diatomite based materials were investigated as a support filter for silica particle coating. The silica sol for coating was synthesized by a st$\ddot{o}$ber process. The diatomite support was dry-pressed at 10 MPa and sintered at $1200^{\circ}C$ for 1 hour. The coating sol was prepared as a mixture of EtOH and silica sol. The diatomite support was coated by a dip-coating process. Silica coated diatomite filter was sintered at $1000{\sim}1200^{\circ}C$ for 1 hour. The largest pore size was decreased with increasing concentration ratio of coating sol. The gas and water permeability of silica coated diatomite decreased with increasing of concentration ratio of the coating sol.