• Title/Summary/Keyword: Nano-silicate

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Geotechnical behaviour of nano-silica stabilized organic soil

  • Kannan, Govindarajan;Sujatha, Evangelin Ramani
    • Geomechanics and Engineering
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    • v.28 no.3
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    • pp.239-253
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    • 2022
  • Suitable techniques to stabilize organic soil and improve its engineering behaviour are in demand. Despite various alternatives, nano-additives proved to be an effective stabilizer owing to their strength enhancing properties. The study focuses on using nano-silica as a potential stabilizer to improve organic silt. Soil was treated with four dosages of nano-silica namely 0.2%, 0.4%, 0.6% and 0.8% of dry weight of the soil. Nano-silica treated soil showed a strength increase of nearly 25% at a dosage of 0.4% after curing for two hours. Strength of the treated soil improved with age. Strength improved by nearly 62.9% after 28 days of curing and 221.4% after 180 days of curing due to formation of Calcium - Silicate - Hydrate (CSH) gel in the soil matrix. Dosage of 0.6% nano-silica is observed to be the optimum dosage. Coefficient of permeability and compression index showed an increase by 13.32 and 5.5 times respectively owing to aggregation of particles and creation of void spaces as visualized from the scanning electron micrographs. Further model foundation study and numerical parametric studies using PLAXIS 2D indicate that optimized and economic results can be obtained by varying the additive dosage with depth.

Synthesis of Inorganic-Organic Composite Electrolyte Membranes for DMFCs (DMFC용 무기-유기 복합 전해질 막의 합성)

  • Kim, Eun-Hyung;Yoon, Gug-Ho;Park, Sung-Bum;Oh, Myung-Hoon;Kim, Sung-Jin;Park, Yong-Il
    • Journal of the Korean Ceramic Society
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    • v.45 no.2
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    • pp.119-125
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    • 2008
  • The FAS(Fluoroalkylsilane)/Nafion inorganic-organic composite electrolyte membrane was successfully fabricated through sol-gel method. The FAS having hydrophobic functional group and silanol ligands is impregnated in $Nafion^{(R)}$ membrane to reduce methanol crossover. The prepared FAS/Nafion inorganic-organic composite electrolyte membrane consist of the hydrophobic FAS-derived silicate nano-particles and $Nafion^{(R)}$ matrix showed decrease of methanol crossover and reduction of humidity dependence without large sacrifice of proton conductivity. The microstructural analysis of the composite membranes was performed using FESEM and FTIR. And the effect of the incorporation of the hydrophobic FAS-derived silicate nano-particles into $Nafion^{(R)}$ membrane was investigated via solvent uptake, membrane expansion rate, humidity dependency of proton conductivity and contact angle measurement.

The preparation and characterization of poly(ethylene terephthalate)(PET)/layered silicate nanocomposite (PET 나노복합재료의 제조 및 특성분석)

  • 천상욱;손세범;곽승엽
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2003.10a
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    • pp.21-24
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    • 2003
  • In general, to enhance physical properties of PET-layered silicate nanocomposites $(P_{et}LSNs)$, it has been well known that the organic modifiers should introduce into gallery regions. However, the organic modifiers in$(P_{et}LSNs)$ may result in thermal decomposition by melt processing at high temperature, and it necessarily lead to deteriorate various physical properties of final products. Therefore, in this study, $(P_{et}LSNs)$ excluding and including organic modifiers were prepared by solution method $(S-P_{et}LSNs_{eom} and S-P_{et}LSNs_{iom})$ and we (focused on the effects of the organic modifiers in $P_{et}$ LSNs with exfoliation structure on the crystallization behaviors, the optical transparency, the thermal stability and the mechanical property. The absence and existence of organic modifiers in $S-P_{et}LSNs_{eom} and S-P_{et}LSNs_{iom}$ were investigated by EA and TGA, and nano-structure of silicate layers in $S-P_{et}LSNs$ was evaluated by using WXRD, SAXS and TEM. $S-P_{et}LSNs_{eom} and S-P_{et}LSNs_{iom}$ were mixed with neat PET as masterbatches by melt method $(M-P_{et}LSNs_{eom} and M-P_{et}LSNs_{iom})$, and also neat PET was mixed with organically modified layered silicates (OLS) by conventional direct melt method $(D-P_{et}LSNs) at 270^{\circ}C$. As results, it was found that $M-P_{et}LSNs_{eom}, M-P_{et}LSNs_{iom}, and D-P_{et}LSN$ showed a exfoliated structure and exhibited faster crystallization rate, better thermal stability and mechanical property than those of neat PET due to the dispersed and detaminated silicate layers in PET matrix. Whereas, considering organic modifiers effect, $M-P_{et}LSNs_{eom} and D-P_{et}LSN$ exhibited slower crystallization rate, poorer optical, thermal and mechanical properties, in comparison to $M-P_{et}LSNs_{eom}> due to the thermal decomposition of organic modifier in $D-P_{et}LSNs$ during melt method.

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Resistive Switching Effects of Zinc Silicate for Nonvolatile Memory Applications

  • Im, Minho;Kim, Jisoo;Park, Kyoungwan;Sok, Junghyun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.35 no.4
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    • pp.348-352
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    • 2022
  • Resistive switching behaviors of a co-sputtered zinc silicate thin film (ZnO and SiO2 targets) have been investigated. We fabricated an Ag/ZnSiOx/highly doped n-type Si substrate device by using an RF magnetron sputter system. X-ray diffraction pattern (XRD) indicated that the Zn2SiO4 was formed by a post annealing process. A unique morphology was observed by scanning electron microscope (SEM) and atomic force microscope (AFM). As a result of annealing process, 50 nm sized nano clusters were formed spontaneously in 200~300 nm sized grains. The device showed a unipolar resistive switching process. The average value of the ratio of the resistance change between the high resistance state (HRS) and the low resistance state (LRS) was about 106 when the readout voltage (0.5 V) was achieved. Resistance ratio is not degraded during 50 switching cycles. The conduction mechanisms were explained by using Ohmic conduction for the LRS and Schottky emission for the HRS.

A Study on the Properties of Traditional Korean Roof Tile by Using Nano Alumino Silicate (전통한식기와의 나노알루미노실리케이트 첨가에 따른 성능연구)

  • Kim, Soon-Ho
    • Journal of the Korea Institute of Building Construction
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    • v.20 no.5
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    • pp.425-432
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    • 2020
  • The appearance of Korean traditional roof tiles is beautiful and excellent in water resistance, fire resistance and durability, but a high sintering temperature of 1,200℃ or higher is required. Therefore, due to the economical and heavy weight problem, the current trend is to use different roof finishing materials than Korean traditional roof tiles. By adding nanoaluminosilicate to clay and kaolin, which are the materials of the clay roof tiles, the sintering temperature is sintered at a low temperature of 1,000℃ or less, and the optimal mixing and material process is designed to satisfy the characteristics required as a Korean traditional roof tile. The results of this study again demonstrate the superiority of Korean traditional tiles with roof finishing materials using nanoaluminate. The properties of Korean traditional roof tiles that satisfy the criteria of KS F 3510 by applying fire resistance of natural minerals and nanoparticle technology to flexural strength of 2800N, Bulk specific gravity of 2.0g/㎤ and absorption rate of less than 10.0%, through which and researched materials development.

Nano-Silica effect on the physicomechanical properties of geopolymer composites

  • Khater, H.M.
    • Advances in nano research
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    • v.4 no.3
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    • pp.181-195
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    • 2016
  • Addition of nano-$SiO_2$ (NS) to geopolymer composites has been studied through measurement of compressive strengths, FTIR and XRD analysis. Alumino-silicate materials are coarse aggregate included waste concrete and demolished walls with its cementing binder, cement kiln dust (CKD) used and can possess a pronouncing activation for the geopolymer reaction resulting from the high alkali contents within. Materials prepared at water/binder ratios in a range of 0.30: 0.40 under curing of $40^{\circ}C$ and 100% Relative Humidity (R.H.), while the used activator is sodium hydroxide in the ratio of 2 wt. %. First, CKD is added in the ratio from 10 up to 50 wt., %, and the demolished walls was varied depending on the used CKD content, while using constant ratio of waste concrete (40 wt., %). Second step, depending on the optimum CKD ratio resulted from the first one (40 wt. %), so the control geopolymer mix composed of cement kiln dust, demolished walls and waste concrete in the ratio (40:20:40, wt %). Nano-silica partially replaced waste concrete by 1 up to 8%. Results indicated that, compressive strengths of geopolymer mixes incorporating nano-silica were obviously higher than those control one, especially at early ages and specially with 3%NS.

Low Temperature Synthesis of Willemite Powder (Willemite 분말의 저온합성)

  • Son, Se-Gu;Lee, Ji-Hyeon;Lee, Jeong-Mi;Kim, Young-Do
    • Journal of the Korean Ceramic Society
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    • v.45 no.7
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    • pp.401-404
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    • 2008
  • Willemite ($Zn_2SiO_4$) are a wide range of applications such as a phosphor host and an important crystalline phase in glass ceramics, electrical insulators, glazes, and pigments. In this study, Willemite precursors were synthesized with zinc silicate gels from mixture of zinc nitrate solution and various sodium silicate solution by the geopolymer technique. To examine the crystallization behavior, precursors were have been monitored by the XRD. A pure willemite phase was obtained at $900^{\circ}C$. TEM investigations revealed that the sample with 50 nm particle size was obtained via heat-treated at $900^{\circ}C$ for W-3.

Investigation on the Structural Changes of Calcium Silicate Hydrates in Nanosilica-incorporated Cement Pastes exposed to Heating using Nuclear Magnetic Resonance Spectroscopy (핵자기 공명을 활용한 가열에 따른 나노실리카 혼입 시멘트 페이스트 내 칼슘실리케이트 수화물 구조 변화 해석)

  • Suh, Heongwon;Li, Pei-Qi;Liu, Jun-Xing;Bae, Sungchul
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2020.11a
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    • pp.151-152
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    • 2020
  • When concrete is exposed to fire, the thermal decomposition of hydrates of Portland cement paste results in critical damage to the concrete structure of a building. Recently, nanosilica arose as the effective nano-additive which can enhance the thermal resistance of the cementitious materials. However, the mechanism of the enhancement was not elucidated specifically. In this study, we investigated the properties of calcium silicate hydrates(C-S-H)of the nanosilica incorporated cement paste after heating to different heating temperatures (200℃, 500℃, and 800℃) by 29Si nuclear magnetic resonance. The results showed that the polymerization of C-S-H of nanosilica incorporated samples was larger than ordinary cement paste after heating to 200℃, and C-S-H formed during heating process to 500℃ due to the pozzolanic reaction during heating process.

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Effect of Slurry Characteristics on Nanotopography Impact in Chemical Mechanical Polishing and Its Numerical Simulation (기계.화학적인 연마에서 슬러리의 특성에 따른 나노토포그래피의 영향과 numerical시뮬레이션)

  • Takeo Katoh;Kim, Min-Seok;Ungyu Paik;Park, Jea-Gun
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2003.11a
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    • pp.63-63
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    • 2003
  • The nanotopography of silicon wafers has emerged as an important factor in the STI process since it affects the post-CMP thickness deviation (OTD) of dielectric films. Ceria slurry with surfactant is widely applied to STI-CMP as it offers high oxide-to-nitride removal selectivity. Aiming to control the nanotopography impact through ceria slurry characteristics, we examhed the effect of surfactant concentration and abrasive size on the nanotopography impact. The ceria slurries for this study were produced with cerium carbonate as the starting material. Four kinds of slurry with different size of abrasives were prepared through a mechanical treatment The averaged abrasive size for each slurry varied from 70 nm to 290 nm. An anionic organic surfactant was added with the concentration from 0 to 0.8 wt %. We prepared commercial 8 inch silicon wafers. Oxide Shu were deposited using the plasma-enhanced tetra-ethyl-ortho-silicate (PETEOS) method, The films on wafers were polished on a Strasbaugh 6EC. Film thickness before and after CMP was measured with a spectroscopic ellipsometer, ES4G (SOPRA). The nanotopogrphy height of the wafer was measured with an optical interferometer, NanoMapper (ADE Phase Shift)

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Leaching of Ca, Fe and Si in Electric Arc Furnace Steel Slag by Aqueous Acetic acid Solution for Indirect Carbonation (간접탄산염화를 위한 전기로제강슬래그 중 Ca, Fe 및 Si 성분의 초산수용액 침출)

  • Youn, Ki-Byoung
    • Resources Recycling
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    • v.26 no.1
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    • pp.37-42
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    • 2017
  • It has been reported that aqueous indirect carbonation process of calcium silicate mineral could be one of the most promising methods for $CO_2$ sequestration. The process consists of two main steps, extraction of Ca from calcium silicate and carbonation of the extracted solution by $CO_2$. Many types of acids such as HCl and $HNO_3$ can be used in the extraction step of the process. In the case of using aqueous acetic acid solution as the extraction solvent, acetic acid can be reproduced at the carbonation step of the extracted solution by $CO_2$ and recycled to extraction step for reuse it. Industrial by-products such as iron and steel slags are potential raw materials of the indirect carbonation process due to their high contents of calcium silicate. In this study, in order to examine the extraction efficiency of domestic electric arc furnace steel slag by aqueous acetic acid solution, extraction experiments of the slag were performed by using the aqueous acetic acid solutions of varying extraction conditions ; acetic acid concentrations, extraction temperatures and times.