• 헤리티지:역사와 과학
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• 제44권4호
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• pp.130-141
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• 2011

본 연구에서는 넓은 pH영역에서도 증점효과를 가지는 카보풀 수지 940, 934를 가지고 중화제(sodium meta silicate, triethylamine)별 겔을 제조하여 10% 과산화요소를 첨가하고, 이에 따른 표백효과를 알아보았다. 실험 결과 메타규산나트륨(sodium meta silicate) 1.6g을 첨가한 실험군에서 표백효과의 최적 조건인 pH 10을 충족시키고 있다. 또한 각군별 대조군 Baseline 색 변화량(${\Delta}E*ab$)과 시간별 색 변화량(${\Delta}E*ab$)을 비교해 보면 1군(카보풀 940, 메카규산나트륨, 과산화요소)은 CS-2에서 112%, CS-4는 63.3%, CS-6은 87.4%의 표백효율을 나타냈으며, 2군(카보풀 934, 메카규산나트륨, 과산화요소; CS-8, CS-10, CS-12)에서는 순서대로 77.3%, 67.3%, 109.%로 나타났다. 그리고 3군(카보풀 940, 트리에탄올아민, 과산화요소;CT-1, CT-3, CT-5)에서 36.8%, 73.2%, 74% 순으로, 4군(카보풀 934, 트리에탄올아민, 과산화요소; CT-6, CT-8, CT-10)에서는 81.7%, 95.4%, 95.7%의 표백효율을 보였다. 따라서 중화제 비율이 증가함에 따라 표백표율이 높아지는 것을 알 수 있었으며 메타규산나트륨을 중화제로 첨가한 것보다 트리에탄올을 중화제로 첨가한 것이 표백효율이 다소 높은 것을 알 수 있었다. 그러나 실험에 사용된 겔의 점도는 메타규산나트륨을 첨가한 군에서 점도가 트리에탄올아민을 첨가한 겔보다 높았다. 이는 유약이 시유된 경사진 도자기 표면에 표백겔이 흐르지 않고 부착되는 장점이 될 수 있다. 그러므로 10% 과산화요소 표백겔을 만들고자 할 때 메타규산 나트륨을 첨가하면 증점효과와 원하는 표백효과를 얻을 수 있을 것으로 판단된다.

• Bulletin of the Korean Chemical Society
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• 제17권8호
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• pp.696-699
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• 1996

Silicate and borosilicate gels were prepared by the sol-gel process and thermally treated in the 150-850 ℃ temperature range. Solid-state 1H MAS and 29Si CP/MAS NMR spectroscopy were used to investigate the effects of heat treatments on the silicate gel to glass conversion process. The 1H NMR isotropic chemical shifts and the relative intensities of hydrogen bonded and isolated silanol groups have been used to access the information concerning the dehydration process on the silicate gel surface. The 29Si NMR isotropic chemical shifts affected by the local silicon environment have been used to determine the degree of crosslinking, i.e. the number of siloxane bonds. These NMR results suggest that the silicate gel to glass conversion process is occurred by two stages which are dependent on the temperature; (1) the formation of particles up to 450 ℃ and (2) the formation of large particles by aggregation of each separated single particle above 450 ℃. In addition, the effects of B atom on the formation of borosiloxane bonds in borosilicates have been discussed.

• Bulletin of the Korean Chemical Society
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• 제17권2호
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• pp.158-162
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• 1996

The steady-state emission and fluorescence lifetimes of 1,3-dipyrenylpropane were measured in silicate sol-gel and xerogel matrices. In sol solution, the fluorescence emission spectra of monomer and excimer resemble those in hydrocarbon solvents. In gel and xerogel condition, however, the fluorescence spectra exhibit significant change, largely confirming the intramolecular motions in gel pores are influenced by microviscosity. The rate constants for intramolecular excimer formation were obtained from the measured fluorescence lifetimes and the rate processes for excimer forming in silicate sol-gel are described by a simple kinetic scheme.

• 한국세라믹학회지
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• 제26권5호
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• pp.625-630
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• 1989

Aluminium silicate gels were prepared by gel-technique using Al(OH)3 and TEOS as starting materials. Aluminium silicate gel as formed mullite at 120$0^{\circ}C$. From this method, homogeneous mullite was formed available needle-like shaped and close compacted. As excess SiO2 mullite composition, the needle-like shaped crystal, size according to increased with SiO2, was increased from 3${\mu}{\textrm}{m}$ to 7${\mu}{\textrm}{m}$ but liquid phase did not affect the formation of needle-like shaped mullite. As excess Al2O3 mullite composition, the needle-shape mullite crystal could not be detected because Al2O3 acted as chunky behavior.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.433-436
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• 2005

The Fly-ash makes an Alumino-silicate gel when it mixes an alkali or a silicate solution. This Alumino-silicate gel is produced to the activation of an alkali silicate. And this act to the binder and makes a combine of particles. This study involved mechanical strengths of an Alumino-silicate Gel based the Fly-ash with an alkali solution. NaOH, KOH were utilized to an alkali solution. The alkali solution concentration was varied from 6 to 12M and the some added also the Meta-kaolin, Waterglass so that it made high the mechanical performance. Based on the experimental result, the compressive strengths increased as the quantity of the Meta-kaolin increased. And a mechanical strengths appeared according to the concentration of an alkali solution so that it was different. XRD, FT-IR have been used to characterize mechanical performance.

• The Korean Journal of Ceramics
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• 제6권4호
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• pp.359-363
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• 2000

Reduced nicotinamide adenine dinucleotide (NADH) was encapsulated in transparent porous sol-gel silicate gels using by different organoalkoxysilane precursor. Characteristics optical absorption and fluorescence of NADH in the gels were examined with depending on NADH concentration and compared. Optical absorption in the aminopropyltrimethoxysilane (APTMS) gel is highest and remains constant during aging the gel. Thus, it is found that NADH in the APTMS gel is most stable and activated. On the other hand, methyltriethoxysilane (MTES) gel presents the lowest optical absorption diminishing with aging the gel. Measurable increase of fluorescence with raising the NADH concentration is observed except for the APTMS gel due to its solubility in the buffer during fluorescence measurement.

• 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.

• The Korean Journal of Ceramics
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• 제2권2호
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• pp.89-94
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• 1996

Aluminum and zinc titanium silicate sol-gel films were fabricated for application of waveguide and the effect of additions of ZnO and $Al_2O_3$ to binary titanium silicate films was investigated. During firing, the films are densified as they shrunk and their refractive index increases in the range of 1.58-1.83 depending on the film composition. The attenuation of the waveguides is not sensitive to changes in composition except for zinc titanium silicate waveguides which have substantially higher attenuation. However, the increase in the attenuation with aging of the waveguides depend upon the composition of waveuides. The addition $Al_2O_3$ or the reduced $SiO_2$ content in the composition appears to slow the deterioration of the waveguides due to the formation of more stable bonds and increased acidity on the film surface. Also, the wavelength dependence of the attenuation of the waveguides varies with composition. The attenuation of the waveguides except for the $65SiO_2{\cdot}35TiO_2$ composition are not Rayleigh scatter limited, suggesting the absorption loss of the waveguides due to the effects of residual carbon and structural defects in the films.

• 한국재료학회지
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• 제24권5호
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• pp.271-276
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• 2014

Silica nano-powder (SNP) is an inorganic material able to provide high-performance in various fields because of its multiple functions. Methods used to synthesize high purity SNP, include crushing silica minerals, vapor reaction of silica chloride, and a sol-gel process using TEOS and sodium silicate solution. The sol-gel process is the cheapest method for synthesis of SNP, and was used in this study. First, we investigated the shape and the size of the silica-powder particles in relation to the variation of HCl and sodium silicate concentrations. After drying, the shape of nano-silica powder differed in relation to variations in the HCl concentration. As the pH of the solution increased, so did the density of crosslinking. Initially, there was NaCl in the SNP. To increase its purity, we adopted a washing process that included centrifugation and filtration. After washing, the last of the NaCl was removed using DI water, leaving only amorphous silica powder. The purity of nano-silica powder synthesized using sodium silicate was over 99.6%.

• Bulletin of the Korean Chemical Society
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• 제23권8호
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• pp.1169-1172
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• 2002