• Title/Summary/Keyword: silicate

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Chemical characteristics of mineral trioxide aggregate and its hydration reaction

  • Chang, Seok-Woo
    • Restorative Dentistry and Endodontics
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    • v.37 no.4
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    • pp.188-193
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    • 2012
  • Mineral trioxide aggregate (MTA) was developed in early 1990s and has been successfully used for root perforation repair, root end filling, and one-visit apexification. MTA is composed mainly of tricalcium silicate and dicalcium silicate. When MTA is hydrated, calcium silicate hydrate (CSH) and calcium hydroxide is formed. Formed calcium hydroxide interacts with the phosphate ion in body fluid and form amorphous calcium phosphate (ACP) which finally transforms into calcium deficient hydroxyapatite (CDHA). These mineral precipitate were reported to form the MTA-dentin interfacial layer which enhances the sealing ability of MTA. Clinically, the use of zinc oxide euginol (ZOE) based materials may retard the setting of MTA. Also, the use of acids or contact with excessive blood should be avoided before complete set of MTA, because these conditions could adversely affect the hydration reaction of MTA. Further studies on the chemical nature of MTA hydration reaction are needed.

A Study on the Preparation and Flame Retardancy of Compatibilized Blend/Layered Silicate Nanocomposites with Inorganic Flame Retardant (무기계난연제 첨가형 상용화블렌드/층상실리케이트 나노복합재료의 제조 및 난연특성에 관한 연구)

  • Kang, Young-Goo;Song, Jong-Hyeok
    • Journal of the Korean Society of Safety
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    • v.21 no.1 s.73
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    • pp.79-85
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    • 2006
  • Olefinic compatibilized blend(R-PP/R-PE)/layered silicate composites have been prepared by melt intercalation technique directed from $Na^{+}$ montmorillonite(MMT) or organophilic montmorillonites while using magnesium hydroxide as flame retardant. Morphology and flammability properties were characterized by X-ray diffraction(XRD), transmission electron microscopy(TEM), scanning electron microscopy(SEM), thermogravimetry analysis(TGA), limiting oxygen index(LOI), UL94 test. It is found that the compatibilized blend/layered silicate(Cloisite 20A) nanocomposites have a mixed immiscible-intercalated structure and there is better intercalation when a compatibilizer is combined with the polymer and layered silicate to be melt blended. A very large increase in the LOI value was observed with hybrid filler addition and further enhancement in thermal stability and compatibility of blend was obtained for the compatibilized blend containing small amount of layered silicate.

Synthesis of Ga-silicate and Its Catalytic Performance for NO Removal under the Presence of Water

  • Misook Kang;Yoon, Yong-Soo;Um, Myeong-Heon
    • Journal of Korean Society for Atmospheric Environment
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    • v.15 no.E
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    • pp.1-8
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    • 1999
  • Catalytic performance for NOx removal by Ga-incorporated silicates(Ga-silicate; Gallosilicate) with MFI type synthesized by the rapid crystallization method was reported in this study. NOx removal was investigated under the condition of O2 excess(10%), with various hydrocarbons of low concentrations. Effect of H2O(2%) addition was also considered. The result showd that the conversion from NOx to N2 was enhanced on the Ga-silicate compared with the Al-silicate. Furthermore, the performance for NOx conversion on the Ga-silicate increased with addition of water.

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Surface Layer Change of Concrete with Concrete Impregnant (침투성 함침제에 따른 콘크리트 표층부의 개질특성)

  • Song, Hun;Shin, Hyeong-UK;Chu, Yong-Sik;Lee, Jong-Kyu
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2013.11a
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    • pp.200-201
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    • 2013
  • This study is interested in manufacturing the concrete surface impregnants including tetra ethyl ortho silicate, alkali silicate for the repair of the exposed concrete and the color concrete requiring the advanced function in view of the concrete appearance. The surface layer change and porosity properties was tested for the review of application. The result of this study show that the effective silicate are tetra ethyl ortho silicate and alkali silicate t. The adhesion in tension is slightly increased but the reinforcement of concrete substrate is slight. So, the concrete impregnant of this study is more desirable for the improvement of durability rather than the reinforcement.

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Effect of Amino Silane Coupling Agent on the AC Electrical Breakdown Phenomena of Epoxy/Layered Silicate Nanocomposite in Needle-plate Electrodes

  • Park, Jae-Jun
    • Transactions on Electrical and Electronic Materials
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    • v.13 no.3
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    • pp.149-152
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    • 2012
  • The effects of amino silane coupling agent on the AC electrical treeing and breakdown behaviors in an epoxy/layered silicate (1 wt%) were examined in needle-plate electrode geometry. A layered silicate was exfoliated in an epoxy base resin by using our AC electric field apparatus. To measure the tree initiation and propagation and the breakdown rate, an alternating current (AC) of 10 kV (60 Hz) was applied to the specimen in needle-plate electrode arrangement with a $30^{\circ}C$ insulating oil bath. In the epoxy/amino silane system, the tree initiation time was 11.5 times higher and the breakdown time was 17.9 times higher than those of the neat epoxy resin. The tree initiation time in the epoxy/layered silicate (1 wt%) system with the amino silane was 2.0 times higher, and the breakdown time was 1.5 times higher than those of the epoxy/layered silicate (1 wt%) system.

A Study of Hydration Characteristics on Soluble Silicate to Develop Fire Protective Coating (방화피복재 개발을 위한 용해성 규산염의 수화특성에 관한 연구)

  • 김정훈;이내우
    • Journal of the Korean Society of Safety
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    • v.11 no.1
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    • pp.90-98
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    • 1996
  • In order to investigate the effects on intumescence to fire protective coatings, the characteristics of solubility, hygroscopic nature and X-ray diffration results on soluble silicate were determined. Solubility is depended on the mutual action of each silicate. In the result of hygroscopic characteristics by water absorption under several kinds of relative humidity, lithium silicate is more stable than sodium and potassium silicate over moistures. Eventhough free water is evaporated over $100^{\circ}C$ , physically adsorption water and ionic water are eliminated about $200^{\circ}C$, but evolution of structural water is expected to be emitted between 400~$600^{\circ}C$ range. Those are considered to be contributed intumescence on soluble silicate.

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Electrical properties of hafnium silicate deposited by atomic layer deposition as a function of annealing temperature (ALD 방법으로 증착된 Hf-silicate 박막의 열처리온도에 따른 전기적 특성)

  • Seo, Young-Sun;Kim, Nam-Hoon;Roh, Young-Han
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2007.11a
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    • pp.107-108
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    • 2007
  • In order to investigate the electrical properties of Hf-silicate as a function of annealing temperature, Hf-silicate deposited by atomic layer deposition (ALD) was studied. After Hf-silicate film deposition, annealing was proceeded at $500^{\circ}C\;and\;700^{\circ}C$. The hysteresis of C-V curves and trapping charge densities were decreased after annealing process. As annealing temperature became higher from $500^{\circ}C\;to\;700^{\circ}C$, the capacitance equivalent thickness (CET) was increased from 1.66 nm to 1.76 nm and the leakage current at -1 V was decreased from $1.70{\times}10^{-4}\;to\;5.68{\times}10^{-5}\;A/cm^2$.

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Optimal Synthesis Conditions of Synthetic Aluminum Silicate (합성규산 알루미늄의 최적합성조건)

  • 신화우;서민재;정동훈
    • YAKHAK HOEJI
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    • v.47 no.1
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    • pp.5-9
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    • 2003
  • Synthetic aluminum silicate was prepared by reacting aluminum sulfate solution with Sodium silicate solution in this study. The optimum synthesis conditions based on the yield of the product were established by applying Box-Wilson experimental design. The results were found to be as follows; Reactant temperature : 50∼72$^{\circ}C$, Concentration of two reactants : 10∼17.6%, Mole ratio of two reactants, [Sod. silicate]/[Al. sulfate) : 4.6∼5.0, Temperature of washing water : 25∼4$0^{\circ}C$, and Drying temperature of product : 50∼$65^{\circ}C$. The physical and chemical properties of synthetic aluminum silicate as medicine were investigated by means of chemical analysis, adsorption test and acid consuming capacity measurements.

Assessment of Silicate Fetilizers Application Affecting Soil Properties in Paddy Field (논토양에서 규산질비료 시용이 토양 환경에 미치는 영향)

  • Joo, Jin-Ho;Lee, Seung-Been
    • Korean Journal of Soil Science and Fertilizer
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    • v.44 no.6
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    • pp.1016-1022
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    • 2011
  • Application of silicate fertilizers is typically practiced with several year's interval to amend soil quality and improve rice productivity at the paddy field in Korea. Most of silicate fertilizers applied in Korea is slag-originated silicate fertilizer. Some water soluble silicate fertilizers are manufactured and commercially available. The objective of this study was to assess changes of soil chemical properties in paddy field by applying slag-originated silicate fertilizer and water soluble silicate fertilizer. Field experiment was conducted on a silt loam paddy soil, where four levels of each silicate fertilizer were applied in soil at the rate of 0, 1, 2, 4 times of the recommended levels. Application of slag-originated silicate fertilizer increased soil pH, while no significant pH increase occurred with the treatment of water soluble silicate fertilizers. Soil pH increased 0.4~0.5 with the 1 time of recommended level of slag-originated silicate fertilizer. Available $SiO_2$ contents also significantly increased with the treatment of slag-originated silicate fertilizer at 15 and 35 days after treatment, while decreased after 60 days after treatment possibly due to rice uptake. Exchangeable Ca, Mg and available phosphate contents in soil increased with application of slag-originated silicate fertilizer, while a little increases for them were shown with the application of soluble silicate fertilizer. $SiO_2$/N ratios in rice straw for 1 time of recommended level of slag-originated silicate fertilizer was 11.5, while that of control was 8.4, which was much lower value. Throughout this study, soil application of slag-originated silicate fertilizer enhanced soil chemical properties, while water soluble silicate fertilizer application in soil needs further study resulting in a little effects on soil property.

Effect of Growth and Nitrogen Use Efficiency by Application of Mixed Silicate and Nitrogen Fertilizer on Zoysiagrass Cultivation (한국잔디 재배에 규산질 비료 시비가 생육과 질소이용효율에 미치는 영향)

  • Han, Jeong-Ji;Lee, Kwang-Soo;Park, Yong-Bae;Bae, Eun-Ji
    • Weed & Turfgrass Science
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    • v.3 no.2
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    • pp.137-142
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    • 2014
  • This study was conducted to investigate the effect of silicate mixed with nitrogen fertilizer on improving the growth and reducing nitrogen input of zoysiagrass. Plant height, fresh and dry weight of shoots, roots, and stolons, the number of shoots and total of stolons length were increased with highest in silicate mixed with nitrogen 24 kg/10a than nitrogen 24 kg/10a, and it showed no significance in silicate mixed with nitrogen 18 kg/10a. Nitrogen use efficiency in mixed silicate fertilizer was increased by 25-30% than single nitrogen fertilization. Moreover, the contents of available $SiO_2$, and organic matters of silicate fertilization on soil was higher than not silicate fertilization on soil. The silicate enhanced the growth and density of zoysiagrass, while it was a crucial factor to affect the chemical property of the soil.