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Journal articles on the topic 'SiO2'

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Author: Grafiati

Published: 4 June 2021

Last updated: 25 May 2024

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1

Liu, Peng, Qiang Ma, Yongwei Chen, Shujin Chen, Jie Zhu, Peng He, Xiaojiang Chen, Xiao Jin, and Bin Zheng. "Study on the Effect of “3D-rGO” Buffer Layer on the Microstructure and Properties of SiO2f/SiO2 and TC4 Brazed Joint." Materials 17, no. 6 (March 19, 2024): 1394. http://dx.doi.org/10.3390/ma17061394.

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Brazing a SiO2f/SiO2 composite with metals is often faced with two problems: poor wettability with the brazing alloy and high residual stress in the joint. To overcome these problems, we report a combined method of selective etching and depositing reduced graphene oxide (rGO) on the surface of a SiO2f/SiO2 composite (3D-rGO-SiO2f/SiO2) to assist brazing with TC4. After the combined treatment, a “3D-rGO” buffer layer formed on the surface layer of the SiO2f/SiO2, and the contact angle was reduced from 130° to 38°, which meant the wettability of active brazing alloy on the surface of SiO2f/SiO2 was obviously improved. In addition, the “3D-rGO” buffer layer contributed to fully integrating the brazing alloy and SiO2f/SiO2; then, the infiltration of the brazing alloy into the surface layer of the SiO2f/SiO2 was enhanced and formed the reduced graphene oxide with a pinning structure in the three dimensional (“3D-pinning-rGO”) structure. Moreover, the joining area of the brazing alloy and SiO2f/SiO2 was expanded and the mismatch degree between the SiO2f/SiO2 and TC4 was reduced, which was achieved by the “3D-pinning-rGO” structure. Furthermore, the concentration of the residual stress in the SiO2f/SiO2-TC4 joints transferred from the SiO2f/SiO2 to the braided quartz fibers, and the residual stress reduced from 142 MPa to 85 MPa. Furthermore, the 3D-pinning-rGO layer facilitated the transfer of heat between the substrates during the brazing process. Finally, the shear strength of the SiO2f/SiO2-TC4 joints increased from 12.5 MPa to 43.7 MPa by the selective etching and depositing rGO method.

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2

Xue, Yu, Letian Qi, Zhaoyun Lin, Guihua Yang, Ming He, and Jiachuan Chen. "High-Strength Regenerated Cellulose Fiber Reinforced with Cellulose Nanofibril and Nanosilica." Nanomaterials 11, no. 10 (October 11, 2021): 2664. http://dx.doi.org/10.3390/nano11102664.

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In this study, a novel type of high-strength regenerated cellulose composite fiber reinforced with cellulose nanofibrils (CNFs) and nanosilica (nano-SiO2) was prepared. Adding 1% CNF and 1% nano-SiO2 to pulp/AMIMCl improved the tensile strength of the composite cellulose by 47.46%. The surface of the regenerated fiber exhibited a scaly structure with pores, which could be reduced by adding CNF and nano-SiO2, resulting in the enhancement of physical strength of regenerated fibers. The cellulose/AMIMCl mixture with or without the addition of nanomaterials performed as shear thinning fluids, also known as “pseudoplastic” fluids. Increasing the temperature lowered the viscosity. The yield stress and viscosity sequences were as follows: RCF-CNF2 > RCF-CNF2-SiO22 > RCF-SiO22 > RCF > RCF-CNF1-SiO21. Under the same oscillation frequency, G’ and G” decreased with the increase of temperature, which indicated a reduction in viscoelasticity. A preferred cellulose/AMIMCl mixture was obtained with the addition of 1% CNF and 1% nano-SiO2, by which the viscosity and shear stress of the adhesive were significantly reduced at 80 °C.

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3

Kosa, Ladislav, Ivan Nerád, Jozef Strečko, Ivo Proks, and Katarína Adamkovičová. "Differential Enthalpies of Solution of Components in Binary Systems 2 CaO . Al2O3 . SiO2-CaO . Al2O3 . 2 SiO2, CaO . SiO2-CaO . Al2O3 . 2 SiO2 and CaO . SiO2-2 CaO . Al2O3 . SiO2." Collection of Czechoslovak Chemical Communications 58, no. 9 (1993): 1989–96. http://dx.doi.org/10.1135/cccc19931989.

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Differential enthalpies of solution of components in binary systems 2 CaO . Al2O3 . SiO2-CaO . Al2O3 . 2 SiO2, CaO . SiO2-CaO . Al2O3 . 2 SiO2 and CaO . SiO2-2 CaO . Al2O3 . SiO2 as the function of composition and temperature were determined on the base of isothermal composition dependences of enthalpies of mixing and temperature dependences of heats of fusion of their pure components. From the values of the first differential heat of solution of CaO . Al2O3 . 2 SiO2 and 2 CaO . Al2O3 . SiO2 in CaO . SiO2 over temperature range considered we can conclude that the reactions were closed chains of SiO4 tetrahedra in CaO . SiO2 melt break, are exothermic. On the other hand positive values of this quantity for CaO . SiO2 in CaO . Al2O3 . 2 SiO2 and 2 CaO . Al2O3 . SiO2 led us to the conclusion that the progressive breaking originally closed chains in CaO . SiO2 melt has endothermic character.

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4

Xu, Chang Ming, Shi Wei Wang, Xiao Xian Huang, and Jing Kun Guo. "Influence of Pressure on the Crystallization in SiO_2f/SiO₂ Composites." Key Engineering Materials 336-338 (April 2007): 1236–38. http://dx.doi.org/10.4028/www.scientific.net/kem.336-338.1236.

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The influence of pressure on the crystallization behavior in SiO2f/SiO2 composites hotpressed at 1350°C was studied. The crystalline phase composition analysis on SiO2f/SiO2 composites revealed that the formation of cristobalite was promoted when the hot-pressing pressure ≤ 12 MPa, however suppressed with higher pressure applied. It can be ascribed to the nucleation mechanism change from surface nucleation to bulk nucleation. Analysis on relative density as well as fracture microstructure of SiO2f/SiO2 composites confirmed the conclusion.

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5

Mao, Huahai, Olga Fabrichnaya, Malin Selleby, and Bo Sundman. "Thermodynamic assessment of the MgO–Al2O3–SiO2 system." Journal of Materials Research 20, no. 4 (April 1, 2005): 975–86. http://dx.doi.org/10.1557/jmr.2005.0123.

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Thermodynamic properties of the phases in the MgO–Al2O3–SiO2 system were assessed, resulting in a set of self-consistent thermodynamic data. The two ternary compounds, cordierite and sapphirine, were optimized from subsolidus reactions. The liquid phase was described by the ionic two-sublattice model with a new species AlO2−1, yielding the formula (Al+3,Mg+2)P(AlO2−1,O−2,SiO4−4,SiO20)Q. Projection of the liquidus surface was calculated. Various isothermal and isoplethal sections were compared with the experimental data.

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6

Ci, Ji Liang, Feng Dan Cui, Li Li Zhang, Jian Zhang, Yi Lv, Ying Min Zhao, and Hao Zhang. "Study on the Highe-Temperature Mechanical of Al<sub>2</sub>O<sub>3f</sub>/SiO<sub>2</sub> and SiO<sub>2f</sub>/SiO<sub>2</sub> Ceramic Matrix Composites." Solid State Phenomena 330 (April 12, 2022): 91–98. http://dx.doi.org/10.4028/p-6kd5u0.

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Al2O3f/SiO2 and SiO2f/SiO2 ceramic matrix composites were manufactured by silica sol-infiltration-sintering method. The mechanical properties of composites under room temperature to 1200 °C were tested on-line with universal testing machine. It is found that Al2O3f/SiO2 composites present a higher strength than SiO2f/SiO2 at room temperature and 1000 °C. The strength of two composites dramatic decrease with temperature increased to 1200 °C. Also, SEM and XRD methods were adopted to investigate the micro-structure of cross-fraction and crystal phase of composites, indicating a strong interaction between fibers and matrix under high temperature. Finally, the dielectric properties of two composites under room temperature to 1200 °C were discussed.

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7

Han, Shu Ang, Kai Hui Jiang, and Jun Wu Tang. "Studies on Preparation and Property of 2.5D SiO_2f/ SiO₂ Composites." Advanced Materials Research 79-82 (August 2009): 1767–70. http://dx.doi.org/10.4028/www.scientific.net/amr.79-82.1767.

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In this paper, 2.5D SiO2f/SiO2 composites were fabricated via sol-gel process employing 2.5D braided silica fiber fabrics as reinforcements and high pure silicasol as slurry. The process parameters are optimized and the optimal parameters are as follows: the silicasol of 30.8 wt. % as slurry, microwave drying, and sintering at 900 °C. Utilizing the optimal process parameters, the density and the flexural strength of the composites can reach 1.65 g•cm-3 and 80.68 MPa respectively. Dielectric properties of the 2.5D SiO2f/SiO2 composites were also measured, and the real part of the permittivity is 3.40 at 5 GHz. The excellent mechanical and dielectric properties of the 2.5D SiO2f/SiO2 composites can well meet the requirements of radome materials.

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8

Urakawa, Satoru, Toru Inoue, Takanori Hattori, Asami Sano-Furukawa, Shinji Kohara, Daisuke Wakabayashi, Tomoko Sato, Nobumasa Funamori, and Ken-ichi Funakoshi. "X-ray and Neutron Study on the Structure of Hydrous SiO2 Glass up to 10 GPa." Minerals 10, no. 1 (January 20, 2020): 84. http://dx.doi.org/10.3390/min10010084.

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The structure of hydrous amorphous SiO2 is fundamental in order to investigate the effects of water on the physicochemical properties of oxide glasses and magma. The hydrous SiO2 glass with 13 wt.% D2O was synthesized under high-pressure and high-temperature conditions and its structure was investigated by small angle X-ray scattering, X-ray diffraction, and neutron diffraction experiments at pressures of up to 10 GPa and room temperature. This hydrous glass is separated into two phases: a major phase rich in SiO2 and a minor phase rich in D2O molecules distributed as small domains with dimensions of less than 100 Å. Medium-range order of the hydrous glass shrinks compared to the anhydrous SiO2 glass by disruption of SiO4 linkage due to the formation of Si–OD deuterioxyl, while the response of its structure to pressure is almost the same as that of the anhydrous SiO2 glass. Most of D2O molecules are in the small domains and hardly penetrate into the void space in the ring consisting of SiO4 tetrahedra.

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9

Radev, Lachezar, Liliana Pavlova, Bisserka Samuneva, Elena Kashchieva, Irena Mihailova, Maria Zaharescu, Barbara Malic, and Luminita Predoana. "Sol-gel synthesis and structure of La2O3-CoO-SiO2 powders." Processing and Application of Ceramics 2, no. 2 (2008): 103–8. http://dx.doi.org/10.2298/pac0802103r.

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LaCoO3 powders are studied because they exhibit interesting electrical, magnetic and catalytic properties. In this paper, new synthesized La2O3-CoO-SiO2 powders with different quantity of silica were prepared via solgel method in aqua media, starting from metal nitrates with different chelating agents. The relation between the reaction in solution, crystallization pathway and morphology were discussed. In LaCoO3-SiO2 powders, depending on the content of SiO2 and the treatment temperature (700-1100?C), different crystalline phases (LaCoO3, Co2 SiO4 and La9.31 (SiO4 )6 O2) were observed with the crystallite sizes ranging from 50 to 100 nm. It was proved that chemical composition and nature of used additives has influence on the phase formation and structure of obtained nanomaterials.

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10

Jiang, Yun, and Zhen Kai Wan. "Studies on Tensile and Shear Properties of 3D Six-Directional SiO_2f/SiO₂ Composites." Advanced Materials Research 1048 (October 2014): 436–39. http://dx.doi.org/10.4028/www.scientific.net/amr.1048.436.

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SiO2f/SiO2 composites reinforced with 3D six-directional preform were fabricated by silicasol-infiltration-sintering method. To characterize the mechanical properties of the composites, mechanical testing was carried out under various loading conditions, including tensile and shear loading. All of the testing curves exhibited highly nonlinear behavior. The results indicated that the 3D six-directional braided SiO2f/SiO2 composites exhibited superior tensile properties and good shear resistant. Therefore, the 3D six-directional braided composites developed can well meet the demands of the thermal structure component.

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11

Leśniak, M., J. Partyka, and M. Sitarz. "Influence of SiO2/Al2O3 Molar Ratio on Phase Composition and Surfaces Quality of Aluminum Silicate Sanitary Glazes in the SiO2-Al2O3-CaO-Na2O System." Archives of Metallurgy and Materials 61, no. 4 (December 1, 2016): 1739–46. http://dx.doi.org/10.1515/amm-2016-0279.

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Abstract This paper presents the results of research on aluminum silicate sanitary glazes in the SiO2-Al2O3-CaO-Na2O system with different SiO2/Al2O3 molar ratio. XRD, SEM-EDS and FITR measurement indicated that SiO2/Al2O3 molar ratio has a significant impact on the phase composition of the obtained glazes. Glass-ceramic glazes were obtained that consisted of both the glass phase and pseudowollastonite (Ca3[SiO3]3) or anorthite (Ca[Al2Si2O8]) crystals. Subsequently, the influence of phase composition on surface quality (roughness) was examined for the obtained samples. On the basis of the conducted examination of glaze surface roughness was observed that glazes of extreme SiO2/Al2O3 molar ratio are characterized with greatest surface roughness when compared to other glazes.

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12

Li, Yandong, Tongsheng Zhang, Yefeng Feng, Chengjun Liu, and Maofa Jiang. "Liquid Regions of Lanthanum-Bearing Aluminosilicates." Materials 13, no. 2 (January 17, 2020): 450. http://dx.doi.org/10.3390/ma13020450.

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The Al2O3-SiO2, La2O3-Al2O3, and La2O3-SiO2 binary phase diagrams were estimated by Redlich–Kister expression. La4.67Si3O13 (=La4.67(SiO4)3O) was introduced to improve the existing phase diagrams. The Al2O3-SiO2-La2O3 ternary phase diagram extrapolated by Kohler method was optimized. Then, the liquidus of Al2O3-SiO2-La2O3 system at 1600 °C was compared with Al2O3-SiO2-RE2O3 (RE = Rare Earth Elements) systems and experimental results in other literature. The high temperature experiments were conducted in the tube furnace at 1500 °C. Then the field emission scanning electron microscope (FE-SEM), energy dispersive spectrometer (EDS), and X-ray diffraction (XRD) were employed to verify the calculated liquid region and precipitates phase at 1500 °C. Moreover, the liquidus of binary systems were compared with FactSage results and experiments. The optimized ternary phase diagram shows the relatively reliable region of liquid phase, and it is significant to the seal glass of solid oxide fuel cells and other fields being related to RE containing silicates.

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13

Vorob’ev, Alexey, Andrey Isakov, Alexander Galashev, and Yuri Zaikov. "DFT-based calculations of silicon complex structures in the KF-KCl-K2SiF6 and KF-KCl-K2SiF6-SiO2 melts." Journal of the Serbian Chemical Society 84, no. 10 (2019): 1129–42. http://dx.doi.org/10.2298/jsc190225044v.

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The length and energy of bonds in the complex anions of silicon formed in KF?KCl?K2SiF6 and KF?KCl?K2SiF6?SiO2 melts were evaluated using the method of first-principles molecular dynamics, accomplished by means of the Siesta program. The effect of K+ (from the second coordination sphere) on the stability of these complexes was studied. The bond lengths in the silicon complexes was found to change with increasing amount of the potassium ions. It was established that the following complexes [SiO4]4-, [SiO3F]3- and [SiF6]2- are the most stable in KF?KCl?K2SiF6 and KF?KCl? ?K2SiF6?SiO2 melts. The [SiO4]4- and [SiF6]2- complexes are thermally stable in the molten salt in the temperature range of 923?1073 K, whereas the [SiF7]3- structure, which is typical for the lattice of crystalline K3SiF7, is unstable in this temperature range. In the KF?KCl?K2SiF6?SiO2 melts, conditions above 1043 K were created allowing the transformation of [Si?3F]3- into [SiO4]4-. Within the studied temperature mode, the Si?F bond length is in the range 1.5? ?1.9 ? and the Si?O bond lengths is 1.5?1.7 ?. The obtained results are in a good agreement with in situ data of Raman spectroscopy for the KF?KCl?K2SiF6 and KF?KCl?K2SiF6?SiO2 melts.

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14

Cui, Su Ping, Ling Ling Liu, Jing Chen, Ya Li Wang, Jian Feng Wang, Hui Wang, and Shi Jie Dong. "Influence of SiO₂/Al₂O₃ Content on Structure and Hydration Activity of Granulated Blast Furnace Slag." Key Engineering Materials 633 (November 2014): 240–44. http://dx.doi.org/10.4028/www.scientific.net/kem.633.240.

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Granulated blast furnace slag (GBFS) is a by-product of manufacturing iron. Samples of GBFS with different ratio of SiO2/Al2O3 were prepared by simulating the actual process of GBFS in laboratory. This study investigated the influence of SiO2/Al2O3 content on structure and hydration activity of GBFS which were characterized by X-ray fluorescence (XRF), powder X-ray diffraction (XRD), infrared radiation (IR) and mechanical testing. It is found that the vitreous content of each sample is above 97% and the hydration activity indexes of 7d and 28d of samples significantly decrease with the increase of SiO2/Al2O3 ratio. The IR characteristic absorption spectrum shows that the silicates mainly exist in [SiO4]-tetrahedra and the aluminum atoms are in different coordination states and the bonding strengths rise with the increase of SiO2/Al2O3 ratio.

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15

Zhou, FangMing, DongHao Xu, MingXiao Shi, and YanHua Bi. "Investigation on microstructure and its transformation mechanisms of B2O3-SiO2-Al2O3-CaO brazing flux system." High Temperature Materials and Processes 39, no. 1 (March 31, 2020): 88–95. http://dx.doi.org/10.1515/htmp-2020-0021.

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AbstractThe B2O3-SiO2-Al2O3-CaO brazing fluxes and slags were investigated by using X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The microstructure of the fluxes and slags and its transformation mechanism during the brazing process were investigated, especially the effect of ratio of B2O3to SiO2(B2O3/SiO2) on the microstructural transformation was analyzed. The results show that the structure units of the fluxes and slags are [BO4], [BO3], [SiO4], [AlO4] and [AlO6], and the network structure is a silicon-boron network structure. The O in the slags consist of bridged oxygen, non-bridged oxygen and free oxygen. During the brazing process, part of the [BO4] in slag combined with silica-oxygen network to form Si-O-B structure, which contribute to the network structure of slag, and another part of the [BO4] was transformed to [BO3]. The increase of (B2O3/SiO2) contribute to the transformation of [BO4] to [BO3], and more B2O3 take part in the interface reaction with the increase of (B2O3/SiO2). Therefore, the increase of (B2O3/SiO2) leads to the decrease in the viscosity of the slag, which is beneficial to the spreading behavior during the brazing process.

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16

Chen Libai, 陈丽白, 郭震宁 Guo Zhenning, and 杨小儒 Yang Xiaoru. "Exciton Energy Levels of (nc-Si/SiO2)/SiO2 Multi-Layer Quantum Dots Structure." Acta Optica Sinica 29, no. 5 (2009): 1320–23. http://dx.doi.org/10.3788/aos20092905.1320.

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17

Hernández, M. A., M. Asomoza, F. Rojas, S. Solís, R. Portillo, M. A. Salgado, C. Felipe, Y. Portillo, and F. Hernández. "Trapping of BTX compounds by SiO2, Ag–SiO2, Cu–SiO2, and Fe–SiO2 porous substrates." Chemosphere 81, no. 7 (November 2010): 876–83. http://dx.doi.org/10.1016/j.chemosphere.2010.08.004.

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18

Ma, Q., Z. R. Li, H. W. Niu, Z. Y. Wang, J. Ba, J. L. Qi, J. C. Feng, P. He, and J. Ma. "The effect of crystal structure of SiO2 on the wettability of AgCuTi SiO2f/SiO2 system." Vacuum 157 (November 2018): 124–27. http://dx.doi.org/10.1016/j.vacuum.2018.08.046.

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19

Wang, Hong Sheng, Ling Li, Chong Hai Wang, Yong Li, and Qi Hong Wei. "Effect of Tetraethoxysilane Infiltration on Properties of 2.5D Quartz Fibers Reinforced Silica." Advanced Materials Research 105-106 (April 2010): 635–38. http://dx.doi.org/10.4028/www.scientific.net/amr.105-106.635.

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In this study, 2.5 dimensional quartz fibers reinforced fused silica (2.5D SiO2f/SiO2) composites were prepared by in-situ solidification vacuum-assisted liquid-phase infiltration method using Si-sol and tetraethoxysilane. Composites’ tensile strength and compressive strength were tested by universal testing machine, and the microstructures of the specimen were observed by scanning electron microscopy (FEI Sirion 200). The ultimate sintering temperature was chosen by the differential thermal analysis of tetraethoxysilane gel and the effect of sintering temperature on the composites’ tensile strength. Densification behavior, mechanical properties and microstructures of the composites were investigated. The results show that tetraethoxysilane infiltration process is an efficient route for the preparation of SiO2f/SiO2 composites, after two cycles when the weight was no longer increased using Si-Sol infiltration, the density of SiO2f/SiO2 composites increases from 1.63 to 1.74g/cm3, while the tensile strength and compressive strength, respectively, increase from 31.2 to 52.7MPa and 59.0 to 129.7 MPa. And the interface de-bonding and distinct fibers pull-out of the fracture faces show that it is non-brittle fracture. The enhanced mechanism of tetraethoxysilane infiltration was also analyzed in this paper.

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20

Park, J. C., J. M. Choi, J. W. Oh, J. T. Choi, S. S. Kim, H. M. Choi, and S. B. Hahn. "TEM characterization of LPCVD Ta2O5 films fabricated by pre-deposition rapid thermal nitrtdation." Proceedings, annual meeting, Electron Microscopy Society of America 54 (August 11, 1996): 960–61. http://dx.doi.org/10.1017/s0424820100167263.

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Chemical vapor deposited tantalum pentoxide (Ta2O5) films have been a promising dielectric material for a storage capacitor in high-density DRAM with three-dimensional cell architecture, due to its higher dielectric constant than that of conventional SiO2 or Si3N4/SiO2 films. The effective dielectric constant of Ta2O5 films is influenced by the thickness of interfacial lower-dielectric Si02 layer which could be a native oxide or a thermally grown oxide during deposition and annealing. In general, the capacitor with the thinner SiO2 layer has the larger effective dielectric constant. In this work, the capacitor structure films prepared with or without RTN treatment, which was performed to inhibit the growth of SiO2, were studied by various TEM techniques.Two samples were prepared to compare the characteristics of the Ta2O5 films fabricated with or without RTN treatment Ta2O5 films were deposited on a phosphorus-doped polysilicon on a p-type silicon substrate by low pressure chemical vapor deposition (LPCVD).

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21

Okada, Kiyoshi, Hiroshi Kawashim, Shigeo Hayashi, Mikio Sugai, and Kenneth J. D. MacKenzie. "Crystallization behavior and cordierite formation in rapidly quenched MgAl2O4–SiO2 glasses of various chemical compositions." Journal of Materials Research 13, no. 5 (May 1998): 1351–57. http://dx.doi.org/10.1557/jmr.1998.0191.

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Crystallization behavior of various compositions of MgAl2O4 –SiO2 glasses was investigated. Glasses with chemical compositions from MgAl2O4/SiO2 = 1/1 to 1/8, spanning the range of cordierite composition (1:2.5) were prepared by a rapid quenching method using an arc image furnace and twin roller. During thermal treatment, all the glasses first crystallized to form high-quartz solid solution (HQss), then transformed to high-cordierite at higher temperature. Transformation from high-cordierite to low-cordierite required prolonged firing times even at high temperature. The crystallization temperature of HQss and the transformation temperature from HQss to high-cordierite changed only slightly in the glasses with MgAl2O4/SiO2 ratios greater than cordierite composition, whereas large increases were found for glasses with MgAl2O4/SiO2 ratios lower than cordierite. The HQss phase appeared in the samples spanning a wide MgAl2O4/SiO2 range and showed superlattice reflections which doubled the fundamental lattice parameters. The cause for HQss formation prior to the appearance of cordierite in these glass samples is discussed from a structural viewpoint involving ordering-disordering of SiO4 and AlO4 tetrahedra deduced from 29Si and 27Al MAS-NMR spectra.

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22

Tong, Q. Y., G. Fountain, and P. Enquist. "Room temperature SiO2∕SiO2 covalent bonding." Applied Physics Letters 89, no. 4 (July 24, 2006): 042110. http://dx.doi.org/10.1063/1.2240232.

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23

Narváez, L., O. Dominguéz, J. R. Martı́nez, and F. Ruiz. "Preparation of (Ni–B)/SiO2, Ni/SiO2 and NiO/SiO2 nanocomposites." Journal of Non-Crystalline Solids 318, no. 1-2 (April 2003): 37–42. http://dx.doi.org/10.1016/s0022-3093(02)01877-x.

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24

Smith, Miranda L., Andrew Campos, and James J. Spivey. "Reduction processes in Cu/SiO2, Co/SiO2, and CuCo/SiO2 catalysts." Catalysis Today 182, no. 1 (March 2012): 60–66. http://dx.doi.org/10.1016/j.cattod.2011.07.026.

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25

Gan, Yanling, Suping Cui, Xiaoyu Ma, Hongxia Guo, and Yali Wang. "Preparation of Cu-Al/SiO2 Porous Material and Its Effect on NO Decomposition in a Cement Kiln." Materials 13, no. 1 (December 30, 2019): 145. http://dx.doi.org/10.3390/ma13010145.

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Nitrogen oxide (NOx) emissions have attracted much attention for increasing concern on the quality of the atmospheric environment. In view of NO decomposition in the cement production process, the preparation of Cu-Al/SiO2 porous material and its effect on NO decomposition were studied, and the denitrification mechanism was proposed in this paper. The NO decomposition performance of the Cu-Al/SiO2 porous material was tested via the experimental setup and infrared spectrometer and micro gas chromatography (GC). The result shows that the Cu-Al/SiO2 porous material with the template of cetyltrimethylammonium bromide (CTAB) had a better NO decomposition rate than materials with other templates when the temperature was above 500 °C, and NO decomposition rate could approach 100% at high temperatures above 750 °C. Structure analysis indicates that the prepared Cu-Al/SiO2 material structure was a mesoporous structure. The X-Ray Diffraction (XRD) and Ultraviolet–visible spectrophotometry (UV–Vis) results of the denitrification product show that the Cu-Al/SiO2 material mainly decomposed to Cu2O and Si2O, and the CuO decomposed to Cu2O and O2 at high temperature. The Cu(I)O was considered as the active phase. The redox process between Cu(II)O and Cu(I)O was thought to be the denitrification mechanism of the Cu-Al/SiO2 porous material.

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26

Han,, Guifang, Litong Zhang,, and Laifei Cheng,. "Processing and Performance of Porous SiO2f /SiO2 Composites." Science and Engineering of Composite Materials 14, no. 4 (December 2007): 329–34. http://dx.doi.org/10.1515/secm.2007.14.4.329.

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27

Xu, Chang-Ming, S. W. Wang, X. X. Huang, and J. K. Guo. "Processing and properties of unidirectional SiO2f/SiO2 composites." Ceramics International 33, no. 4 (May 2007): 669–73. http://dx.doi.org/10.1016/j.ceramint.2005.12.017.

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Erlbacher, T., M. P. M. Jank, M. Lemberger, A. J. Bauer, and H. Ryssel. "HfSiO/SiO2- and SiO2/HfSiO/SiO2-gate stacks for non-volatile memories." Thin Solid Films 516, no. 21 (September 2008): 7727–31. http://dx.doi.org/10.1016/j.tsf.2008.04.038.

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Li, Y. B., Y. Bando, D. Golberg, and Y. Uemura. "SiO2-sheathed InS nanowires and SiO2 nanotubes." Applied Physics Letters 83, no. 19 (November 10, 2003): 3999–4001. http://dx.doi.org/10.1063/1.1626259.

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Boccuzzi, F., S. Coluccia, G. Martra, and N. Ravasio. "Cu/SiO2 and Cu/SiO2–TiO2 Catalysts." Journal of Catalysis 184, no. 2 (June 1999): 316–26. http://dx.doi.org/10.1006/jcat.1999.2428.

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Boccuzzi, F., G. Martra, C. Partipilo Papalia, and N. Ravasio. "Cu/SiO2 and Cu/SiO2–TiO2 Catalysts." Journal of Catalysis 184, no. 2 (June 1999): 327–34. http://dx.doi.org/10.1006/jcat.1999.2429.

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32

Baldamus, Gerd, Hartmut Hobert, Klaus Klostermann, and Georg Rudakoff. "Adsorption stickstoffhaltiger Verbindungen an Ni/SiO2-Präparaten; Adsorption von NH3 an Ni/SiO2-, NiO/SiO2-und SiO2-Präparaten." Zeitschrift für Chemie 21, no. 9 (August 31, 2010): 338–39. http://dx.doi.org/10.1002/zfch.19810210918.

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Liu, Liping, Xi Liu, Xinjian Bao, Qiang He, Wei Yan, Yunlu Ma, Mingyue He, Renbiao Tao, and Ruqiang Zou. "Si-Disordering in MgAl2O4-Spinel under High P-T Conditions, with Implications for Si-Mg Disorder in Mg2SiO4-Ringwoodite." Minerals 8, no. 5 (May 12, 2018): 210. http://dx.doi.org/10.3390/min8050210.

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A series of Si-bearing MgAl2O4-spinels were synthesized at 1500–1650 °C and 3–6 GPa. These spinels had SiO2 contents of up to ~1.03 wt % and showed a substitution mechanism of Si4+ + Mg2+ = 2Al3+. Unpolarized Raman spectra were collected from polished single grains, and displayed a set of well-defined Raman peaks at ~610, 823, 856 and 968 cm−1 that had not been observed before. Aided by the Raman features of natural Si-free MgAl2O4-spinel, synthetic Si-free MgAl2O4-spinel, natural low quartz, synthetic coesite, synthetic stishovite and synthetic forsterite, we infer that these Raman peaks should belong to the SiO4 groups. The relations between the Raman intensities and SiO2 contents of the Si-bearing MgAl2O4-spinels suggest that under some P-T conditions, some Si must adopt the M-site. Unlike the SiO4 groups with very intense Raman signals, the SiO6 groups are largely Raman-inactive. We further found that the Si cations primarily appear on the T-site at P-T conditions ≤~3–4 GPa and 1500 °C, but attain a random distribution between the T-site and M-site at P-T conditions ≥~5–6 GPa and 1630–1650 °C. This Si-disordering process observed for the Si-bearing MgAl2O4-spinels suggests that similar Si-disordering might happen to the (Mg,Fe)2SiO4-spinels (ringwoodite), the major phase in the lower part of the mantle transition zone of the Earth and the benchmark mineral for the very strong shock stage experienced by extraterrestrial materials. The likely consequences have been explored.

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Gao, Yuxiang, Mei Leng, Yangfan Chen, Zhichao Chen, and Jiangling Li. "Crystallization Products and Structural Characterization of CaO-SiO2-Based Mold Fluxes with Varying Al2O3/SiO2 Ratios." Materials 12, no. 2 (January 9, 2019): 206. http://dx.doi.org/10.3390/ma12020206.

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During the casting of high aluminum steel, the dramatic increase in the Al2O3/SiO2 ratio is inevitable, resulting in significant changes of the crystallization behavior, which would result in heat transfer and lubrication problems. Crystallization products and structure characterization of glassy CaO-SiO2-based mold fluxes with different Al2O3/SiO2 ratios were experimentally investigated using a differential scanning calorimetry technique and Raman spectroscopy. With increasing Al2O3/SiO2 ratios, the following results were obtained. The crystallization temperature and the crystallization products are changed. With increasing Al2O3/SiO2 ratios from 0.088 to 0.151, the crystallization temperature first increases greatly from 1152 °C to 1354 °C, and then moderately increases. The crystallization ability of the mold flux is strengthened. The species of the precipitated crystalline phase change from two kinds, i.e., Ca4Si2O7F2 and Ca2SiO4, to four kinds, i.e., Ca4Si2O7F2, Ca2SiO4, 2CaO·Al2O3·SiO2 and Ca12Al14O32F2, the crystallization ability of Ca4Si2O7F2 is gradually attenuated, but other species show the opposite trend. The results of Raman spectroscopy indicate that Al3+ mainly acts as a network former by the information of [AlO4]-tetrahedral structural units, which can connect with [SiO4]-tetrahedral by the formation of new bridge oxygen of Al–O–Si linkage, but there is no formation of Al–O–Al linkage. The linkage of Al–O–Si increases and that of Si–O–Si decreases. The polymerization degree of the network and the average number of bridging oxygens decrease. Further, the relatively strong Si–O–Si linkage gradually decreases and the relatively weak Al–O–Si gradually increases. The change of the crystalline phase was interpreted from the phase diagram and structure.

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Cui, Yi, Rong Lin Wang, Li Ren Wang, Jing Long Bu, and Qian Wang. "Effects of Recycling Ladle Lining Materials on Phase Composition and Microstructure of Al₂O₃-SiC-C Castable for Iron Runner." Advanced Materials Research 652-654 (January 2013): 1614–18. http://dx.doi.org/10.4028/www.scientific.net/amr.652-654.1614.

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In this experiment, preparation of samples were based on original ratio of bauxite matrix Al2O3-SiC-C castable for iron tap channel, and partial bauxites of size 8-5 mm, 5-3 mm, 3-1 mm and 2O3-MgO-C ladle bricks, respectively. Effects of recycling ladle lining materials on phase composition and microstructure of Al2O3-SiC-C castable for iron runner were investigated by XRD, SEM and EDS. The results showed that new phases SiO2 and (Mg0.804Ca0.196)3Al2(SiO4)3 were formed in the castable at 1450 oC in air atmosphere, and the spherical (Mg0.804Ca0.196)3Al2(SiO4)3 was formed on external surface of recycling Al2O3-MgO-C particle. thereinto, SiC oxidation to formed SiO2 with flow pattern character was key element of the phase (Mg0.804Ca0.196)3Al2(SiO4)3 formation. The more fine and uniform of recycling Al2O3-MgO-C particles, the more spherical (Mg0.804Ca0.196)3Al2(SiO4)3 was formed in recycling Al2O3-SiC-C castable. Internal structure of theirs samples exhibited looser state with content increasing of recycling ladle lining materials.

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Wang, Lei, Huihui Wan, Shaohua Jin, Xiao Chen, Chuang Li, and Changhai Liang. "Hydrodeoxygenation of dibenzofuran over SiO2, Al2O3/SiO2 and ZrO2/SiO2 supported Pt catalysts." Catalysis Science & Technology 5, no. 1 (2015): 465–74. http://dx.doi.org/10.1039/c4cy00859f.

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37

Honda, S., T. Shimizu, I. Sakamoto, T. Une, and K. Kawabata. "Mossbauer and XPS analysis of Fe-SiO2 and Fe-SiO2/SiO2 granular films." Microscopy and Microanalysis 8, S02 (August 2002): 1366–67. http://dx.doi.org/10.1017/s143192760210345x.

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38

Eloy, Martinez R., and Nobuo Sano. "Nitrogen solubility in CaO-SiO2, CaO-MgO-SiO2, and BaO-MgO-SiO2 melts." Metallurgical Transactions B 21, no. 1 (February 1990): 97–104. http://dx.doi.org/10.1007/bf02658120.

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39

Jean, Jau-Ho, Yu-Ching Fang, Steve X. Dai, and David L. Wilcox. "Sintering of a Crystallizable K2O–CaO–SrO–BaO–B2O3–SiO2 Glass with Titania Present." Journal of Materials Research 17, no. 7 (July 2002): 1772–78. http://dx.doi.org/10.1557/jmr.2002.0262.

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Crystallization and reaction kinetics of a crystallizable K2O–CaO–SrO–BaO–B2O3–SiO2 glass powder with 17–40 vol% titania powder were investigated. The initially amorphous K2O–CaO–SrO–BaO–B2O3–SiO2 glass powder formed cristobalite (SiO2) and pseudowollastonite [(Ca, Ba, Sr)SiO3] during firing. The above crystalline phases were completely replaced by a crystalline phase of titanite [(Ca, Sr, Ba)TiSiO5] when the amount of added titania was greater than a critical value, e.g., 10 vol%, at 99–1100 °C. A chemical reaction taking place at the interface between titania and the glass was attributed to the above observation. The dissolved titania changed the composition of the glass, and the dissolution kinetics was much faster than the formation of cristobalite and pseudowollastonite. Activation energy analysis showed that the crystallization of titanite [(Ca,Sr,Ba)TiSiO5] was controlled by a reaction-limiting kinetics of formation for the Ti–O bond.

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40

Yuelin, Qin, Liu Hao, and Yang Yanhua. "Structure evolution of blast furnace slag with high Al2O3 Content and 5 mass% TiO2 via molecular dynamics simulation and fourier transform infrared spectroscopy." Metallurgical Research & Technology 115, no. 1 (November 28, 2017): 113. http://dx.doi.org/10.1051/metal/2017090.

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The structure of a quenched blast furnace slag containing 5 mass% TiO2 was investigated via molecular dynamics simulation and Fourier transform infrared spectroscopy. The simulation and experimental results obtained revealed that the slag possesses a depolymerized network of [SiO4] and [AlO4] tetrahedra. At a fixed CaO/SiO2 mass fraction of 1.17 and 12 mass% Al2O3, increasing the amount of MgO decreased the bridging oxygen fraction in the slag system, thus resulting in silicate depolymerization. At a fixed CaO/SiO2 mass fraction of 1.17 and 8 mass% MgO, increasing Al2O3 content increased the bridging oxygen fraction because of the polymerization of aluminate structures. At a fixed 8 mass% MgO and 12 mass% Al2O3, increasing the CaO/SiO2 mass fraction from 1.07 to 1.50 decreased the bridging oxygen fraction because of the depolymerization of silicate and aluminate structures. Analyzing the slag structure via FT-IR spectroscopy verified these behaviors.

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41

Belashchenko, D. K., O. I. Ostrovski, and L. V. Skvortsov. "Molecular dynamics simulation of binary CaO–FeO, MgO–SiO2, FeO–SiO2, CaO–SiO2 and ternary CaO–FeO–SiO2 systems." Thermochimica Acta 372, no. 1-2 (May 2001): 153–63. http://dx.doi.org/10.1016/s0040-6031(01)00451-8.

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42

Ivanova, Iliana A., Elitsa L. Pavlova, Aneliya S. Kostadinova, Radostina D. Toshkovska, Lyubomira D. Yocheva, Kh El-Sayed, Mohamed A. Hassan, Heba El-Sayed El-Zorkany, and Hisham A. Elshoky. "Investigation of Biological and Prooxidant Activity of Zinc Oxide Nanoclusters and Nanoparticles." Acta Chimica Slovenica 69, no. 3 (September 26, 2022): 722–33. http://dx.doi.org/10.17344/acsi.2021.7337.

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Zinc oxide (ZnO) nanomaterials offer some promising antibacterial effects. In this study, a new form of ZnO is synthesized, named ZnO nanocluster bars (NCs). Herein, ZnO NCs, ZnO nanoparticles (NPs), ZnO coated with silica (ZnOSiOA, ZnO-SiOB), and SiO2 NPs were prepared, characterized, and their antimicrobial and prooxidant activity were tested. The prooxidant activity of all nanomaterials was studied according to free-radical oxidation reactions (pH 7.4 and pH 8.5) in chemiluminescent model systems. Each form of new synthesized ZnO nanomaterials exhibited a unique behavior that varied from mild to strong prooxidant properties in the Fenton`s system. ZnO NPs and ZnO NCs showed strong antibacterial effects, ZnO-SiOA NPs did not show any antibacterial activity representing biocompatibility. All tested NMs also underwent oxidation by H2O2. ZnO NCs and ZnO NPs exhibited strong oxidation at pH 8.5 in the O2 –. generating system. While, SiO2, ZnO-SiOA and ZnO-SiOB possessed pronounced 60–80% antioxidant effects, SiO2 NPs acted as a definitive prooxidant which was not observed in other tests. ZnO NCs are strongly oxidized, assuming that ZnO NCs provide a slower release of ZnO, which leads to having a stronger effect on bacterial strains. Thus, ZnO NCs are an important antibacterial agent that could be an emergent replacement of traditional antibiotics.

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43

Zhai, Dajun, Tao Qiu, Jun Shen, and Keqin Feng. "Mechanism of tetraborate and silicate ions on the growth kinetics of microarc oxidation coating on a Ti6Al4V alloy." RSC Advances 13, no. 8 (2023): 5382–92. http://dx.doi.org/10.1039/d2ra07755h.

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B4O72− dissolves molten TiO2 at high temperature, exposing filamentary channels and resulting in the repeated nucleation of microarc in the same area. SiO2 formed from SiO32− blocks the channels and induces microarc nucleation in other regions.

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44

Mead, Robert N., and G. Mountjoy. "Molecular Dynamics Modelling of the Structure of Bioactive (CaO)_0.3 (SiO₂)_0.7 Sol-Gel." Materials Science Forum 514-516 (May 2006): 1059–63. http://dx.doi.org/10.4028/www.scientific.net/msf.514-516.1059.

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Enhanced bioactivity has been observed for amorphous CaO-SiO2 sol-gels with 30mol% CaO, and several structural techniques have recently been used to investigate the structural basis for this bioactivity. The current work presents the first detailed atomic model of (CaO)0.3(SiO2)0.7 solgel after heat treatment at 600°C, produced using molecular dynamics. The model contains 1056 atoms in cubic box with length 24.1Å, and specifically incorporates hydroxyl groups which are characteristic of the sol-gel. The model is in good agreement with experimental X-ray and neutron diffraction results. Inspection of the model shows a network of SiO4 tetrahedra with an average connectivity of approximately 3. Ca have coordination of NCaO=5.3, in agreement with experimental results. On average, each Ca is surrounded by 4 other Ca, and visual inspection shows several large clusters of Ca. These clusters should influence the dissolution of Ca, and hence the bioactivity of (CaO)0.3(SiO2)0.7 sol-gel.

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Hirose, K., H. Nohira, K. Sakano, and T. Hattori. "Atomic structure of SiO2 at SiO2/Si interfaces." Applied Surface Science 166, no. 1-4 (October 2000): 455–59. http://dx.doi.org/10.1016/s0169-4332(00)00469-4.

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46

พันธุลาภ, อุษณีย์, เบญจมล เพ็ชรเจริญมงคล, วราภรณ์ แก้วแดง, and กนิษฐ์ ตะปะสา. "การศึกษาปริมาณ SiO2 ต่อสมบัติไม่ชอบน้ำ และสมบัติทางแสงของฟิล์ม TEOS- SiO2 -OTES บนกระจก." วารสารวิทยาศาสตร์ประยุกต์ กรมวิทยาศาสตร์บริการ 7, no. 7 (October 7, 2022): 41–48. http://dx.doi.org/10.60136/bas.v7.2018.228.

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งานวิจัยนี้มีวัตถุประสงค์เพื่อศึกษาผลของปริมาณ SiO2 ต่อสมบัติความไม่ชอบน้ำในฟิล์มไฮบริดระหว่าง TEOS (Tetraethyl Orthosilicate) และ OTES (Octyitriethoxysilane) ที่สังเคราะห์ด้วยกระบวนการโซล-เจล โดยใช้ TEOS :OTES : โพรพานอล : น้ำ ในอัตราส่วน 24 : 0.6 : 94 : 3 และเติมอนุภาคซิลิกา ปริมาณ 0.5, 1, 3, 5, และ 10 เปอร์เซ็นต์โดยน้ำหนัก จากนั้นเคลือบลงบนผิวกระจกโดยวิธีการปั่นเหวี่ยง และนําไปอบที่อุณหภูมิ 200-450 องศาเซลเซียส เป็นเวลา 20 นาที จากนั้นนํามาศึกษาสมบัติของฟิล์มด้วยเทคนิค FT-IR, UV-VIS Spectroscopy, XRD, AFM และ Contact angle ผลการศึกษาพบว่าเมื่อปริมาณ ซิลิกาเพิ่มขึ้น จะมีค่ามุมสัมผัสของหยดน้ำเพิ่มขึ้น ในขณะที่ค่าการส่องผ่านของแสงลดลง จากการทดลองนี้สรุปได้ว่า ฟิล์มไฮบริด TEOS-OTES ที่ดีที่สุดคือฟิล์มที่เติมซิลิกา 1 เปอร์เซ็นต์โดยน้ำหนัก ซึ่งมีสมบัติความไม่ชอบน้ำ (ค่ามุมสัมผัสของ หยดน้ำ 1194.1 องศา) และฟิล์มยังคงความใส (ค่าการส่องผ่านแสง 75 เปอร์เซ็นต์)

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47

Dinamarca, Robinson, Verónica Valles, Brenda Ledesma, Cristian H. Campos, Gina Pecchi, and Andrea Beltramone. "Magnetic Fe3O4@SiO2–Pt and Fe3O4@SiO2–Pt@SiO2 Structures for HDN of Indole." Materials 12, no. 23 (November 24, 2019): 3878. http://dx.doi.org/10.3390/ma12233878.

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The effect of a second porous SiO2 shell in the activity and selectivity of the Fe3O4@SiO2–Pt catalyst in the hydrodenitrogenation of indole is reported. The double Fe3O4@SiO2–Pt@SiO2 structure was prepared by coating Fe3O4 nanoparticles with tetraethyl orthosilicate (TEOS) with a further impregnation of 1.0 wt.% of Pt on the (3-aminopropyl)triethoxysilane functionalized Fe3O4@SiO2 structures. The second porous SiO2 shell, obtained by using a hexadecyltrimethylammonium bromide (CTAB) template, covered the Fe3O4@SiO2–Pt catalyst with a well-defined and narrow pore-sized distribution. The full characterization by TEM, inductively coupled plasma-optical emission spectroscopy (ICP-OES), XRD, and N2 adsorption isotherm at 77 K and vibrating sample magnetometry (VSM) of the catalysts indicates homogeneous core@shell structures with a controlled nano-size of metallic Pt. A significant effect of the double SiO2 shell in the catalytic performance was demonstrated by both a higher activity to eliminate the nitrogen atom of the indole molecule present in model liquid fuel and the improvement of the catalytic stability reaching four consecutive reaction cycles with only a slight conversion level decrease.

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48

A. Leon y Leon, Carlos, and M. Albert Vannice*. "Adsorption and catalytic properties of Pd/SiO2, Cu/SiO2, and Pd-Cu/SiO2 systems." Applied Catalysis 69, no. 1 (January 1991): 269–90. http://dx.doi.org/10.1016/s0166-9834(00)83307-2.

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A. Leon y Leon, Carlos, and M. Albert Vannice*. "Adsorption and catalytic properties of Pd/SiO2, Cu/SiO2, and Pd-Cu/SiO2 systems." Applied Catalysis 69, no. 1 (January 1991): 291–304. http://dx.doi.org/10.1016/s0166-9834(00)83308-4.

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50

A. Leon y Leon, Carlos, and M. Albert Vannice*. "Adsorption and catalytic properties of Pd/SiO2, Cu/SiO2, and Pd-Cu/SiO2 systems." Applied Catalysis 69, no. 1 (January 1991): 305–21. http://dx.doi.org/10.1016/s0166-9834(00)83309-6.

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