• Title/Summary/Keyword: Na-Si

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Fundamental Study of Alkali Activated Cement Mortar for Evaluating Applicability of Partial-Depth Repair (도로포장 보수재 활용 가능성 평가를 위한 알칼리 활성 시멘트 모르타르 기초연구)

  • Jeon, Sung Il;An, Ji Hwan;Kwon, Soo Ahn;Yun, Kyung Ku
    • International Journal of Highway Engineering
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    • v.15 no.3
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    • pp.1-8
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    • 2013
  • PURPOSES : This study is to evaluate the feasibility of using the alkali activated cement concrete for application of partial-depth repair in pavement. METHODS : This study analyzes the compressive strength of alkali activated cement mortar based on the changes in the amount/type/composition of binder(portland cement, fly ash, slag) and activator(NaOH, $Na_2SiO_3$, $Na_2CO_3$, $Na_2SO_4$). The mixture design is divided in case I of adding one kind-activator and case II of adding two kind-activators. RESULTS : The results of case I show that $Na_2SO_4$ based mixture has superior the long-term strength when compared to other mixtures, and that $Na_2CO_3$ based mixture has superior the early strength when compared to other mixtures. But the mixtures of case I is difficult to apply in the material for early-opening-to-traffic, because the strength of all mixtures isn't meet the criterion of traffic-opening. The results of case II show that NaOH-$Na_2SiO_3$ based mixtures has superior the early/long-term strength when compared to NaOH-$Na_2SiO_3$ based mixtures. In particular, the NaOH-$Na_2SiO_3$ based some mixtures turned out to pass the reference strength(1-day) of 21MPa as required for traffic-opening. CONCLUSIONS : With these results, it could be concluded that NaOH-$Na_2SiO_3$ based mixtures can be used as the material of pavement repair.

A Study on the pH-, pNa- and pK-Sensing Properties of K and Al Coimplanted SiO$_2$ Thin Films (K 및 Al 이중이온주입된 SiO$_2$ 박막의 pH, pNa 및 pK 농도 감지특성에 관한 연구)

  • 김병수;신백균;이붕주;이덕출
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.52 no.7
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    • pp.293-297
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    • 2003
  • Silicon dioxide (SiO$_2$) layers were fabricated on Si$_3$N$_4$/SiO$_2$/Si layer structures by low pressure chemical vapor deposition (LPCVD). Potassium and aluminum were then coimplanted by implanting potassium ions with the energy of 100 [keY] and dose of 5x10$^{16}$ [cm ̄$^2$] and 1x10$^{17}$ [cm ̄$^2$] into an aluminum buffer layer on the SiO$_2$Si$_3$N4/SiO$_2$/Si structure. The pH, pNa, and pK ion sensitivities of the resulting layers were investigated and compared to those of as-deposited silicon dioxide layer. The pK-sensitivity of the silicon dioxide was enhanced by the K and Al coimplantation. On the contrary, the pH and pNa-sensitivities of the coimplanted silicon dioxides were quite lower than that of the as-deposited silicon dioxide.

Dielectric Properties in Na2O-B2O3-SiO2 Glass Containing CoO (CoO를 함유한 Na2O-B2O3-SiO2 계 유리의 유전적 특성)

  • Lee, Chanku;Lee, Sudae;Joung, Maeng-Sig
    • Journal of Korean Ophthalmic Optics Society
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    • v.5 no.1
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    • pp.49-53
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    • 2000
  • Sodium borate silicate glass of composition $10Na_2O-39B_2O_3-50SiO_2-CoO$ and $20Na_2O-14B_2O_3-65SiO_2-CoO$ were prepared by melting oxide mixtures in alumina crucible at $1210^{\circ}C$ in an electric furance in air for 2h, and then quenching in air. The dielectric behavior of the quenched glasses are the subject of the present work. Properties such as dielectric constant and resistivity as a function frequency and temperature are reported. From the dielectric spectra, the glass phase transition temperature has been found to decrease at a rate $Na_2O$ 20 mol% and the dielectric constants increase with increasing $Na_2O$ content. The frequency dependent resistivity response of glass exhibits a non-Debye type relaxation.

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Preparation of NASIglasses by Sol-Gel Process (솔-젤법에 의한 NASIglass의 제조)

  • 김희주;강은태;김종옥
    • Journal of the Korean Ceramic Society
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    • v.32 no.12
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    • pp.1357-1368
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    • 1995
  • Nasigels of composition Na0.75Zr2PSi2O12 and Na3Zr2PSi2O12 have been synthesized by the sol-gel technique using metal alkoxide precursors. The monolithic dry gels of Na0.75Zr2PSi2O12 with no crack have been prepared by the control of the shrinkage rte, but gels of Na3Zr2PSi2O12 were impossible to prepare without cracking. The gels treated up to 80$0^{\circ}C$ led to the formtion of glass but the glasses were converted to the crystalline phases at above this temperature. Crystaline phases precipitated from the Na0.75Zr2PSi2O12 glass were NASICON-like phase, Na2Si2O5, and free Zirconia. Phase that precipitated from the Na3Zr2PSi2O12 was only rhombohedral NASICON. For Na0.75Zr2PSi2O12 gels, framework of PO4 tetrahedra and SiO4(PO4) tetrahedra formed at low temperature but changed to that of SiO4 and SiO4(PO4) tetrahedras as it were crystallized. In the case of Na3Zr2PSi2O12 gel, framework of isolated PO4 and SiO4 tetrahedras formed at low temperature but changed to SiO4(PO4) tetrahedra framework which usually formed in the NASICON crystal after crystallization at high temperature. The gels treated up to 80$0^{\circ}C$ contained the residual water. The ionic conduction was attributed to the motion of proton and Na+ ion at low (up to 150~20$0^{\circ}C$) and high temperatures, respectively. As the temperature of heat treatment increased, ionic conductivity gradaully increased with the extent of precipitation of crystalline phase.

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Silicon Supply through Subirrigation System Alleviates High Temperature Stress in Poinsettia by Enhancing Photosynthetic Rate (저면공급한 규소에 의한 포인세티아의 광합성 능력 향상과 고온 스트레스 경감)

  • Son, Moon Sook;Park, Yoo Gyeong;Sivanesan, Iyyakkannu;Ko, Chung Ho;Jeong, Byoung Ryong
    • Horticultural Science & Technology
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    • v.33 no.6
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    • pp.860-868
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    • 2015
  • The effect of Si supplied during plant cultivation on tolerance to high temperature stress in Euphorbia pulcherrima Willd. 'Ichiban' was investigated. Rooted cuttings were transplanted into 10-cm pots and a complete nutrient solution, containing 0 or $50mg{\cdot}L^{-1}$ Si as either $K_2SiO_3$, $Na_2SiO_3$, or $CaSiO_3$, was supplied through subirrigation or weekly foliar applications. After two months of cultivation, plants were placed in an environment-controlled chamber and subjected to $35{\pm}1^{\circ}C$ (high temperature) conditions for 18 days. Enhanced specific activities of enzymatic antioxidants (APX) and suppressed specific activities of non-enzymatic antioxidants (ELP) were observed in the high temperature-stressed plants with Si application. The Fv/Fm (maximum quantum yield of photosystem II), photosynthetic rate, and Si contents in the shoot increased in the treatments of $K_2SiO_3$ and $Na_2SiO_3$ supplied through subirrigation. The Si-treated plants had more tolerance of high temperature stress than the control plants. Of the Si sources and application methods tested, $K_2SiO_3$ and $Na_2SiO_3$ supplied through subirrigation were found to be the most effective in enhancing tolerance to high temperature stress.

The effect of SiO2, Na2O, and CaO on the isokom temperatures in soda-lime glass (소다석회유리에서 SiO2, Na2O, CaO가 isokom 온도에 미치는 영향)

  • Kang, Seung Min;Kim, Chang-Sam
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.32 no.1
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    • pp.12-15
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    • 2022
  • The effect of SiO2, Na2O and CaO on isokom temperatures in soda-lime glass is estimated by comparing calculated isokom temperatures using viscosity model proposed by Lakatos. The isokom temperatures at the viscosity of log η = 12.3, 10, 6.6 and 1 (Pa·s) are lowered by 6, 7, 10 and 24℃, respectively, by the substitution of SiO2 with Na2O by 1 mol%. Meanwhile, replacing 1 mol% of SiO2 with CaO raises the isokom temperatures by 3~4 and 2℃ at the viscosity of log η = 12.3 and 10 (Pa·s), respectively, but lowers the temperatures by 1 and 21℃ at the viscosity of log η = 6.6 and 1(Pa·s), respectively.

The Effects of Sc on the Microstructure of Hypoeutectic Al-Si Alloys (아공정 Al-Si합금 조직에 미치는 Sc의 효과)

  • Kim, Myung-Han;Lee, Jong-Tae
    • Journal of Korea Foundry Society
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    • v.24 no.3
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    • pp.145-152
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    • 2004
  • The eutectic Si in Al-8.5wt.%Si alloy was changed from large flake to fine lemellar(or fibrous) shape when the Sc amount in the Al-Si alloy reaches 0.2wt.%. The optimum amount of Sc for the best modification effect was 0.8wt.% and slight decrease of modification effect occurred over this value. The study on the distribution of the modifiers(Sr, Na, and Sc) and the measurement of the surface tension of the Al-8.5wt.%Si alloy melt added with Sr, Na, and Sc modifier, respectively, reveals that Sc modifies the eutectic Si by the decrease of surface tension, while Sr and Na modify the eutectic Si mainly by impurity induced twinning mechanism.

Correlation between crystalline phase and corrosion resistance of Mg alloy with different PEO conditions. I. Crystalline phase (Mg 합금의 PEO 공정 조건에 따른 산화피막 결정상과 내부식성에 대한 연구 I. 결정상)

  • Kim, Bae-Yeon;Kim, Yong-Nam;Jeon, Min-Seok;Ham, Jae-Ho
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.28 no.2
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    • pp.74-79
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    • 2018
  • To increase corrosion resistance of Mg alloy, AZ31 and AZ91 were PEO treated with different applied voltage and time conditions. We used Na-P and Na-Si system electrolyte. Crystalline phase and morphology were investigated. MgO was Most common crystal phase and vitreous phase could be found. Crystalline phase of $Na_{3.59}Mg_{2.71}(PO_4)_3$ and $Mg_2SiO_4$ also could be found. Porosity of oxidized surface tends to decrease with increasing PEO applied voltage, treat time and concentration of electrolyte, after then, size of pore increased and total number of pore decreased, distinctly.

The Effect of Fly Ash Composition and Reaction Conditions on Hydrothermal Synthesis of Zeolitic Materials (Fly ash 조성(組成)과 반응조건(反應條件)이 zeolite성(性) 물질(物質)의 열수합성(熱水合成)에 미치는 영향(影響))

  • Choi, Choong-Lyeal;Lee, Dong-Hoon;Park, Man;Choi, Jyung
    • Korean Journal of Soil Science and Fertilizer
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    • v.32 no.1
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    • pp.39-46
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    • 1999
  • This study was performed to examine the effect of initial composition ratio and various reaction conditions on CEC and crystallinity of the product in hydrothermal synthesis of zeolitic materials from fly ash. Na-P1 zeolite was formed from the mixture with $SiO_2/Al_2O_3$ ratio above 2.55, however from the mixture with $SiO_2/Al_2O_3$ ratio below 2.25 hydroxy sodalite was formed. The CEC of reaction product(Na-P1 zeolite) treated with 3N-NaOH, $Na_2O/Al_2O_3$ ratio 2.55 and $SiO_2/Al_2O_3$ ratio 2.0 for 12 hours at $103^{\circ}C$ was about $285cmol^+kg^{-1}$, which was higher than those of the products of other reaction condition. The crystallinity of Na-P1 zeolite as high as 45.1% was attained at the optimum reaction condition of 2N-NaOH, $SiO_2/Al_2O_3$ ratio 2.55, $Na_2O/Al_2O_3$ ratio 1.5 for 12 hours at $103^{\circ}C$. The XRD peak of the reaction product could be measured at 7.16, 5.04, 4.12, 3.18, $2.69{\AA}$ and tetragonal pillar shape observed by SEM image be characteristic for Na-P1 zeolite. Judging from the result, it should be considered the optimum synthesis condition for Na-P1 zeolite from fly ash was 2~3N NaOH, $SiO_2/Al_2O_3$ ratio 2.55 and $Na_2O/Al_2O_3$ ratio 1.5~2.0 for 12 hours at $80{\sim}103^{\circ}C$.

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Physical and Chemical Properties of Soluble Sodium Silicate (수용성 규산나트륨의 물리 · 화학적 특성)

  • Ha, Youn Shick;Park, Kyeong Il;Seo, Moo Lyong
    • Journal of the Korean Chemical Society
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    • v.43 no.2
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    • pp.172-181
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    • 1999
  • To develop the manufacturing technique for the powder builder of amorphous solid types, the water glass mixed with caustic soda dispersed into the methanol. Thus soluble sodium silicate was made a form of amorphous solid powder. In order to examine characteristics of water soluble sodium silicate $SiO_2/Na_2O$ mol ratio, we investigated solubility, thermogram, SEM, and BET analysis. pH buffering capacity, calcium-ion binding capacity as temperature change, and surfactant loading capacity were examined for characteristics as laundry detergent builder. $SiO_2/Na_2O$ molar ratio of soluble sodium silicate was 1.0, 2.4, 2.8, and zeolite was used in order to investigate basic characteristics of laundry detergent builder. Silicate used with laundry detergent was good for pH buffering capacity and solubility. But calcium-ion binding capacity and surfactant adsorption ability were lower. $SiO_2/Na_2O$ mol ratio became higher, pH buffering capacity and ion exchange ability were lower and surfactant adsorption ability was a little higher.

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