Journal articles: 'Silica-stabilized alumina'

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Dechézelles, Jean-François, Carmen Ciotonea, Cezar Catrinescu, Adrian Ungureanu, Sébastien Royer, and Véronique Nardello-Rataj. "Emulsions Stabilized with Alumina-Functionalized Mesoporous Silica Particles." Langmuir 36, no. 12 (March 12, 2020): 3212–20. http://dx.doi.org/10.1021/acs.langmuir.9b03900.

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Дмитриевский, А. А., Д. Г. Жигачева, А. О. Жигачев, and П. Н. Овчинников. "Прочностные свойства циркониевой керамики, упрочненной оксидом алюминия, с добавлением диоксида кремния." Физика твердого тела 63, no. 2 (2021): 259. http://dx.doi.org/10.21883/ftt.2021.02.50475.138.

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The effect of alumina and silica on strength of zirconia ceramics, stabilized with calcia, was studied. We have established the optimal concentrations of the components in the CaO-ZrO2+Al2O3+SiO2 system; these concentrations correspond to the highest flexural strength of 980±70 MPa. The optimal concentration of alumina is 5 wt.% in absence of silica. In terms of compressive strength the highest values of 2.44±0.15 MPa were obtained when concentration of alumina was 5 wt. % and content of silica was 5 mol. %. Stress-strain diagrams indicate presence of plasticity in the materials containing 4-5 mol. % SiO2 by having a yield plateau

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Lin, Yung-Jen, and Lee-Jen Chen. "Reaction synthesis of mullite–silicon carbide–yttria-stabilized zirconia composites." Journal of Materials Research 14, no. 10 (October 1999): 3949–56. http://dx.doi.org/10.1557/jmr.1999.0534.

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SiC/mullite/zirconia composites were fabricated by controlling the oxidation of powder compacts of SiC, alumina, and 3 mol% yttria-stabilized zirconia. The powder compacts were first oxidized in air at 1100 °C for various times to obtain proper amounts of amorphous silica. Subsequent reaction sintering at 1500 °C for 2 h combined the amorphous silica with alumina to form mullite with planned amounts. The incorporation of 3 mol% yttria-stabilized zirconia promoted mullite formation and enhanced the densification of the samples. With ≥10 vol% of 3 mol% yttria-stabilized zirconia in the samples, the temperature of mullite formation was lowered from 1400 to 1300 °C, and mullitization was near completion after sintering at 1500 °C for 2 h. The densification of the samples depended on the contents of SiC and 3 mol% yttria-stabilized zirconia. Samples with 20 vol% SiC and 10–20 vol% 3 mol% yttria-stabilized zirconia could be sintered to reach approximately 97% of theoretical density after sintering at 1500 °C for 2 h.

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Farooq, Ahmad, and Ali Abd El-Aty. "Novel Method of Developing Nanosilica Coated Alumina Micro Abrasives Using Silicon Nanoparticles Generated from Spark Erosion as the Source." Applied Mechanics and Materials 799-800 (October 2015): 479–82. http://dx.doi.org/10.4028/www.scientific.net/amm.799-800.479.

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Silica coated alumina abrasives, used for abrading the surface of Yttria stabilized tetragonal zirconia polycrystal ceramics, were produced in order to achieve successful bonding with resin luting cement. The source of the silica coating was from Silicon Nanoparticles (SiNPs) that were produced from spark erosion in high pressure flushing of deionized water. SEM images verified average size distribution of the SiNPs to be between 30-50nm. In contrast to the tribochemical methods that are used widely to produce such abrasives, a completely novel dry physical process was opted for this experiment. By optimization of the conditions, 2g of purified SiNPs was mixed with 20g of alumina μ-particles (approximated diameter of 100μm), in presence of 25ml ethanol, mixed thoroughly to form slurry. Heated up to 120°C for 20 minutes to evaporate the ethanol, the resultant powder mix was compacted and uploaded in furnace at temperature of 1100°C for 2hrs. This formed an oxide layer on the SiNPs which consequently formed bonding with the alumina particles. SEM/EDS results validate substantial amount of coating of silica on alumina. The paper hereby demonstrates a novel method of producing silica coated alumina abrasives, which is a dry and cleaner substitution method compared to tribochemical approach.

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Zhao, Xiangyun, Yu Cong, Yanqiang Huang, Shuang Liu, Xiaodong Wang, and Tao Zhang. "Rhodium Supported on Silica-Stabilized Alumina for Catalytic Decomposition of N2O." Catalysis Letters 141, no. 1 (November 2, 2010): 128–35. http://dx.doi.org/10.1007/s10562-010-0472-3.

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Carvalho, Cristiane Fonseca, Cláudio Luis Melo-Silva, Claudinei Santos, and Jefferson Fabricio Cardoso Lins. "Effect of Surface Treatment of Yttria Stabilized Zirconia for Dental Prostheses." Materials Science Forum 727-728 (August 2012): 831–36. http://dx.doi.org/10.4028/www.scientific.net/msf.727-728.831.

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When it comes to providing reliable adhesion of low silica content alumina ceramic, hydrofluoric acid etching along with silanization has not shown sufficient efficacy because the microstructure of high-alumina content ceramics is unable to degrade them. The objective of this study was to analyze the effect of surface sandblasting of zirconia-based ceramic stabilized by yttria as used in dental prostheses, using a SEM and roughness average. The samples were divided in control, no surface treatment; Al2O3sandblasting; Al2O3sandblasting and Al2O3+ SIC particles 110 µm average sized; Al2O3sandblasting and Al2O3+ SIC particles 110 µm average sized milled for 2 hours; Al2O3sandblasting and Al2O3+ SIC particles 110 µm average sized milled for 6 hours. The Al2O3sandblasting and the 2-hour milled Al2O3+ SIC particles showed better results and better characterization of roughness in SEM with the silica deposition on the samples surface.

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Melo-Silva, C. L., C. F. Carvalho, T. C. F. Melo-Silva, R. X. Freitas, F. R. F. Silva, and J. F. C. Lins. "Analysis of the Y-TZP Ceramic Substucture in Blasting with Aluminum Oxide before and after Sintering." Materials Science Forum 805 (September 2014): 576–80. http://dx.doi.org/10.4028/www.scientific.net/msf.805.576.

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The objective of this study was to evaluate the microstructure of a ceramic based on yttria stabilized zirconia (Y-TZP) in blasting with aluminum oxide and its effect on the sintering. 25 pre-sintered Y-TZP blocks were obtained. Ten samples were blasted with alumina, and then all samples were sintered and divided into the groups: Control-no treatment; alumina G1-blasted with alumina and sintered; alumina and Rocatec G1-blasted, sintered, and Rocatec; alumina G2-sintered, alumina blasting; alumina and Rocatec G2-sintering, alumina blasting, and Rocatec. The samples were evaluated by a scanning electron microscopy. The qualitative analysis showed that the treated samples had an increase in the surface texture and that group 1– alumina and Rocatec– presented the silica incorporation to be regular and homogeneous. It was concluded that the treatment of pre-sintered surfaces is a good alternative in the bonding strength between the Y-TZP and the resin cements.

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Ma, Xianzheng, Katarzyna Janowska, Vittorio Boffa, Debora Fabbri, Giuliana Magnacca, Paola Calza, and Yuanzheng Yue. "Surfactant-Assisted Fabrication of Alumina-Doped Amorphous Silica Nanofiltration Membranes with Enhanced Water Purification Performances." Nanomaterials 9, no. 10 (September 24, 2019): 1368. http://dx.doi.org/10.3390/nano9101368.

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Surfactant-templated 5 mol% Al2O3-doped silica membranes nanofiltration membranes were synthesized via the sol-gel method, and afterward, were optimized, and tested with respect to the permeability and rejection rate. The disordered silica network was stabilized by doping 5 mol% alumina. Tetraethyl orthosilicate and aluminum isopropoxide were used as the silica and alumina precursors, respectively. Cetyltrimethylammonium bromide (CTAB) was used not only as a pore-forming agent, but also to control the reaction rate of the aluminum isopropoxide, thus obtaining highly homogeneous materials. The results about filtration of model solutions showed that the optimized membranes are featured by both a relatively high water permeability (1.1–2.3 L·m−2·h−1 ·bar−1) and a high rejection for salts (74% for NaCl, and >95% for MgSO4 and Na2SO4) and organic pollutants (e.g., about 98% for caffeine). High rejection of divalent ions and organic molecules was also observed when a real wastewater effluent was filtered. The influence of the synthesis conditions on the membrane performance is discussed.

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Shyu, Jiin-Jyh, and Yuan-Chieh Chen. "Zirconia-mullite ceramics made from composite particles coated with amorphous phase: I. Effect of zirconia addition." Journal of Materials Research 10, no. 1 (January 1995): 63–70. http://dx.doi.org/10.1557/jmr.1995.0063.

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Mullite-based ceramics added with 0–20 vol % stabilized zirconia have been prepared by alumina/zirconia particles coated with an amorphous silica layer. All samples can be densified through the viscous flow of the amorphous silica layer in the typical temperature range of 1100–1310 °C. For the ZrO2-free mullite ceramics, the viscous densification kinetics is inhibited by increasing the content of the alumina inclusion particles and by crystallization of the amorphous silica layer. However, for the zirconia-mullite ceramics, the addition of the zirconia inclusion particles accelerates the viscous densifcation kinetics. Mullitization kinetics is also enhanced by the addition of zirconia. As the sintering temeperature is high, a porous, duplex microstructure is observed in samples with or without zirconia. Zirconia addition enhances the development of this microstructure. As the sintering temperature and/or zirconia content is increased, ZrO2 particles tend to coarsen, resulting in a decreased tetragonal to monoclinic ratio. Fracture toughness KlC increases with the zirconia content. Mullite-20 vol % ZrO2 composite sintered at 1600 °C has a KlC of 3.8 MPa · m1/2.

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Hatmoko, John Tri, and Hendra Suryadharma. "Fundamental factors on the behaviour of bagasse ash stabilized organic soil." MATEC Web of Conferences 258 (2019): 01019. http://dx.doi.org/10.1051/matecconf/201925801019.

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A series of experimental programs was undertaken to investigate mechanical behaviour of bagasse ash stabilized organic soil. Preliminary experiment was done to verify the chemical and physical characteristics of bagasse ash and organic soil. The following experiment was then performed to study the improvement of unconfined compression strength of bagasse ash stabilized organic soil. In this research, three different organic soils and four different bagasse ashes were used. The soil was mixed with 10, 20 and 30% bagasse ash, then a set of unconfined compression tests were performed. In general, the results indicate that the unconfined compression strength of stabilized soil improve proportional to the percentage of bagasse ash. And, the quick lime content (CaO), ratio between quick lime and silica (CaO/SiO2), and ratio between quick lime and the sum of silica and alumina {CaO/(SiO2+Al2O3)} were the fundamental factors affecting the improvement of bagasse ash stabilized soil unconfined compression strength. The significant improvement occurs on 0.25 < (CaO/SiO2) < 1.00, and 0.20< (CaO/(SiO2+Al3O3) < 0.67. In contrast, organic content decreased unconfined compression, and maximum dry density (MDD) of stabilized soil. The addition of bagasse to the organic soil, however, does not significantly improve the unconfined compression strength, then addition of 6, 8, and 10% calcium carbide residue (CCR) was performed to the bagasse ash stbilized organic soil to get better engineering performance of stabilized soil. For 9% CCR, qu improve from 93 to 208 kPa.

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Konovalova, Tatyana A., J. Krzystek, Peter J. Bratt, J. van Tol, Louis-Claude Brunel, and Lowell D. Kispert. "95−670 GHz EPR Studies of Canthaxanthin Radical Cation Stabilized on a Silica−Alumina Surface." Journal of Physical Chemistry B 103, no. 28 (July 1999): 5782–86. http://dx.doi.org/10.1021/jp990579r.

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May, Michele Mirian, Ana Maria Estivalete Marchionatti, Luiz Felipe Valandro, Edson Luiz Foletto, Lucio Strazzabosco Dorneles, and Liliana Gressler May. "Y-TZP surface treatments and their effects on the bond strength to resin cement." Brazilian Journal of Oral Sciences 18 (April 8, 2019): e190918. http://dx.doi.org/10.20396/bjos.v18i0.8655141.

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Aim: This study evaluated the effect of surface treatments of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramics on their bond strength to a resin cement. Methods: Seventy zirconia blocks (6 × 6 × 2 mm3, IPS e.max ZirCAD) were assigned into 7 groups (n=10) – as-sintered (AS), no treatment; tribochemical silica coating + silanization (TBS; Cojet-sand; ProSil); airabrasion with 45 μm alumina particles + universal primer (AAP; Monobond®Plus); fusion sputtering (FS); SiO2 nanofilm + silanization (SN; ProSil); FS+SN+ silanization (FSSN; ProSil); FS+SN+Universal Primer (FSSNP; Monobond®Plus). Afterwards, a resin cement (RelyX™ ARC) was applied inside cylinders (Ø = 0.96 mm × 1 mm height) placed on the zirconia surfaces. Microshear bond strength tests (μSBS) were carried out (1 mm/min). Failure and phase transformation analysis were performed. Bond strength data (MPa) were subjected to Kruskal-Wallis/Mann Whitney tests. Results: TBS (27 ± 1.2) and AAP (24.7 ± 0.8) showed higher bond strengths than the other groups, followed by FSSNP (15.5 ± 4.2) and FSSN (13.3 ± 3.6). FS (3.4 ± 0.44) and SN (9.5 ± 2.7) showed the lowest values (p < 0.001). Most of the specimens exhibited an adhesive failure. Conclusion: Air-abrasion by silica-coated alumina particles followed by silanization or by alumina particles followed by universal primer resulted in the highest resin bond strength to zirconia. Fusion sputtering and silica nanofilm deposition induced low strengths. However, when these methods are applied in combination and with a primer (FSSN and FSSNP), higher bond strengths may be achieved. Low bond strengths are obtained when no zirconia treatment is performed.

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Samodurova, Anastasia, Damjan Vengust, Andraž Kocjan, and Tomaž Kosmač. "The sintering-temperature-related microstructure and phase assemblage of alumina-doped and alumina–silica-co-doped 3-mol%-yttria-stabilized tetragonal zirconia." Scripta Materialia 105 (August 2015): 50–53. http://dx.doi.org/10.1016/j.scriptamat.2015.04.031.

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Švinka, Ruta, Visvaldis Svinka, and Julija Bobrovik. "Modification of Porous Cordierite Ceramic." Key Engineering Materials 721 (December 2016): 322–26. http://dx.doi.org/10.4028/www.scientific.net/kem.721.322.

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Highly porous cordierite ceramic by using of talcum, kaolinite and γ-alumina was obtained by method of slip casting of concentrated suspension. Additives of amorphous silica and non-stabilized zirconia in the amount of 5 wt% were used. Sintering temperature of dried samples was in range of 1250 – 1450°C. All the samples contain crystalline phases of cordierite, mullite and corundum but, depending on the additives, as a result of sintering in addition forms spinel, cristobalite or zircon (ZrSiO4). Porosity of obtained materials changes in large scale from 42 to 59 per cent; it is influenced by both sintering temperature and composition. Compressive strength increases with the addition of zirconia. In comparison, compressive strength of samples without additives or with silica additive does not exceed 3.5 MPa. The increase of coefficient of thermal expansion depends both on the composition and sintering temperature. ZrO2 additive increases the coefficient of thermal expansion considerably.

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Halperin, W. P. "Superfluid 3He in Aerogel." Annual Review of Condensed Matter Physics 10, no. 1 (March 10, 2019): 155–70. http://dx.doi.org/10.1146/annurev-conmatphys-031218-013134.

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Superfluid 3He is an unconventional neutral superfluid in a p-wave state with three different superfluid phases, each identified by a unique set of characteristic broken symmetries and nontrivial topology. Despite natural immunity of 3He from defects and impurity of any kind, it has been found that they can be artificially introduced with high-porosity silica aerogel. Furthermore, it has been shown that this modified quantum liquid becomes a superfluid with remarkably sharp thermodynamic transitions from the normal state and between its various phases. These phases include new superfluid phases that are stabilized by anisotropy from uniform strain imposed on the silica aerogel framework, and they include new phenomena in a new class of anisotropic aerogels consisting of nematically ordered alumina strands. The study of superfluid 3He in the presence of correlated, quenched disorder from aerogel serves as a model for understanding the effect of impurities on the symmetry and topology of unconventional superconductors.

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Lin, Yung-Jen. "Reaction synthesis of mullite-zirconia from mixtures of alumina, silica, and 3 mol% yttria-zirconia powders." Journal of Materials Research 14, no. 3 (March 1999): 916–24. http://dx.doi.org/10.1557/jmr.1999.0123.

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Mullite-zirconia composites were synthesized by reaction-sintering powder mixtures of α-alumina, amorphous silica, and 3 mol% yttria-stabilized zirconia. It is found that the addition of 3 mol% yttria-zirconia improves sintering and lowers the mullitization temperature. It also suppresses the cristobalite formation and enhances zircon formation between 1300 and 1400 °C. Results further suggest that these effects are consequences of modification of the silicate glass by yttria. Samples containing ≥20 vol% of 3 mol% yttria-zirconia could be sintered at 1500 °C for 2 h to obtain dense composites consisting of mullite and tetragonal zirconia. The microstructural investigations of the sintered samples support the viewpoint that mullite formation is via nucleation and growth from aluminosilicate glass. They also reveal that zirconia can hinder the grain growth of mullite and that the coalescence of zirconia grains is accomplished by grain boundary diffusion.

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Baranowska, Katarzyna, Janina Okal, and Włodzimierz Tylus. "Microwave-assisted polyol synthesis of bimetallic RuRe nanoparticles stabilized by PVP or oxide supports (γ-alumina and silica)." Applied Catalysis A: General 511 (February 2016): 117–30. http://dx.doi.org/10.1016/j.apcata.2015.11.045.

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Miškufová, Andrea, Alexandra Medvecová, Anna Kochmanová, Dušan Olčák, and Viktor Hronský. "Problems with Solidification of Fly Ashes from the Municipal Solid Waste Incineration." Applied Mechanics and Materials 832 (April 2016): 31–38. http://dx.doi.org/10.4028/www.scientific.net/amm.832.31.

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One of the negative aspects of MSW (municipal solid waste) incineration is production of hazardous fly ashes. MSW fly ash usually contains heavy metals like for example chromium, lead, cadmium and organic substances (dioxins, furans), soluble compounds (salts) and other harmful substances. According to environmental legislative and with respect to the environment fly ash as a hazardous waste should be stabilized before landfilling. This work deals with certain problems occurring at solidification process of MSW fly ash by cementation. This work also describes efficiency of stabilization by two different binders (slag cement and waste containing alumina and silica). Leachability tests by TCLP (toxicity characteristic leaching procedure) and compressive strength of original and solidified samples by use of uniaxial pressing were studied in order to find suitable parameters for effective stabilization.

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Keyvanloo, Kamyar, Baiyu Huang, Trent Okeson, Hussein Hamdeh, and William Hecker. "Effect of Support Pretreatment Temperature on the Performance of an Iron Fischer–Tropsch Catalyst Supported on Silica-Stabilized Alumina." Catalysts 8, no. 2 (February 12, 2018): 77. http://dx.doi.org/10.3390/catal8020077.

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Graf, Irina V. G., Jeffrey W. Bacon, Mark B. Consugar, Michael E. Curley, Larry N. Ito, and Louis H. Pignolet. "Cluster Chemistry on Surfaces: Characterization and Catalytic Studies of Phosphine-Stabilized Platinum−Gold Clusters on Silica and Alumina Supports." Inorganic Chemistry 35, no. 3 (January 1996): 689–94. http://dx.doi.org/10.1021/ic9504147.

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Wandscher, VF, C. Prochnow, MP Rippe, LS Dorneles, GL Callegari, P. Baldissara, R. Scotti, and LF Valandro. "Retentive Strength of Y-TZP Crowns: Comparison of Different Silica Coating Methods on the Intaglio Surfaces." Operative Dentistry 42, no. 5 (September 1, 2017): E121—E133. http://dx.doi.org/10.2341/16-090-l.

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SUMMARY Objective: To evaluate the effect of different methods of silica deposition on the intaglio surface of yttrium oxide stabilized zirconia polycrystal (Y-TZP) crowns on the retentive strength of the crowns. Methods: One hundred simplified full-crown preparations produced from fiber-reinforced polymer material were scanned, and 100 Y-TZP crowns with occlusal retentions were milled. Crown/preparation assemblies were randomly allocated into five groups (n=20) according to the treatment of the intaglio surfaces: TBS = tribochemical silica coating via air-abrasion with 30-μm silica-coated alumina particles; GHF1 = application of thin glaze layer + hydrofluoric acid (HF) etching for 1 minute; GHF5 = glaze application + HF for 5 minutes; GHF15 = glaze application + HF for 15 minutes; NANO = silica nanofilm deposition (5 nm) via magnetron sputtering. All groups received a silane application. The surfaces of the preparations (polymer) were conditioned with 10% HF for 30 seconds and silanized. The crowns were cemented with resin cement, thermocycled (12,000 cycles; 5°C/55°C), stored for 60 days, and subjected to a retentive strength test (0.5 mm/min until failure). The retention data (MPa) were analyzed using one-way analysis of variance, Tukey tests, and Weibull analysis. Failures were classified as 50C (above 50% of cement in the crown) and 50S (above 50% of cement on the substrate). Results: The TBS (5.6±1.7 MPa) and NANO groups (5.5±1 MPa) had higher retentive strength than the other groups (p<0.0001) and had the highest values of characteristic strength. There was no difference in Weibull modulus, except for the GHF1 group (lower values). The TBS and GHF15 groups, respectively, had 60% and 70% of their failures classified as 50C, while most of the other groups had 50S failures. Conclusion: Tribochemical silica coating and silica nanofilm deposition on the inner surface of zirconia crowns promoted a higher retentive strength.

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Okeson, Trent J., Kamyar Keyvanloo, John S. Lawson, Morris D. Argyle, and William C. Hecker. "On the kinetics and mechanism of Fischer–Tropsch synthesis on a highly active iron catalyst supported on silica-stabilized alumina." Catalysis Today 261 (March 2016): 67–74. http://dx.doi.org/10.1016/j.cattod.2015.08.054.

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Lee, Kang N., Nathan S. Jacobson, and Robert A. Miller. "Refractory Oxide Coatings on SiC Ceramics." MRS Bulletin 19, no. 10 (October 1994): 35–38. http://dx.doi.org/10.1557/s088376940004820x.

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Silicon-based ceramics are leading candidate materials for high-temperature structural applications such as heat exchangers, advanced gas turbine engines, and advanced internal combustion engines. They have excellent oxidation resistance in clean oxidizing environments due to the formation of a slow-growing silica scale (SiO2). However, durability in high-temperature environments containing molten salts, water vapor, or a reducing atmosphere can limit their applications. Molten salts react with silica scale to form liquid silicates. Oxygen readily diffuses through liquid silicates and rapidly oxidizes the substrate. High water vapor levels lead to hydrated silica species, such as Si(OH)4(g) and subsequent evaporation of protective scale. Complex combustion atmospheres containing oxidizing (CO2, H2O) and reducing (CO, H2) gases form SiO2 and then reduce it to SiO(g). In situations with extremely low partial pressures of oxidant, direct formation of SiO(g) occurs. All these reactions can potentially limit the formation of a protective silica scale and thus lead to an accelerated or a catastrophic degradation.One approach overcoming these potential environmental limitations is to apply a barrier coating which is environmentally stable in molten salts, water vapor, and/or reducing atmospheres. Refractory oxides such as mullite (3Al2O3 · 2SiO2), yttria-stabilized zirconia (ZrO2-Y2O3), or alumina (Al2O3) are promising candidate coating materials because of their excellent environmental stability in these severe conditions. Refractory oxide coatings can also serve as thermal barrier coatings because of their low thermal conductivity. Key requirements for an adherent and durable barrier coating include coefficient of thermal expansion (CTE) match and chemical compatibility with the substrate. Mullite in general meets all the requirements and thus appears most promising.

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Sanpo, Noppakun, Jirasak Tharajak, James Wang, and Christopher C. Berndt. "Surface Investigation of Laser Glazed Mullite Thin Films on Yttria-Stabilized Zirconia Coatings." Applied Mechanics and Materials 804 (October 2015): 104–7. http://dx.doi.org/10.4028/www.scientific.net/amm.804.104.

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Thermal barrier coatings (TBCs) are used in the cooled parts of gas turbines to reduce the temperature of blades and hot engine components, allowing higher operating temperatures and yielding increased efficiency. The corrosive gases which come from combustion of low grade fuels can penetrate into the TBCs and reach the metallic components and bond coat and cause hot corrosion and erosion damage. Mullite thin films have been applied onto the top layer of yttria-stabilized zirconia (YSZ) coatings by sol-gel dipping process in order to decrease the porosity as well as improve thermal stability of the coatings. Glazing the top layer by laser beam is an advanced approach to seal TBCs surface. The laser beam has the advantage of forming a dense thin layer composed of micrograins. CO2 laser beam assisted in the densification of the surface by remelting a thin layer of the exposed surface. The laser glazing converted the rough surface of TBCs into smooth micron-sized grains with size of 1-4 microns. Mullite compounds have remained on the surface after laser treatment since alumina and silica are still present, as indicated in EDX spectra. The results revealed that the roughness increases as the grain size decreases.

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Hago, A. W., and Amer Ali Al-Rawas. "An investigation into the Traditional Method of Production of Omani Sarooj." Sultan Qaboos University Journal for Science [SQUJS] 4 (December 1, 1999): 35. http://dx.doi.org/10.24200/squjs.vol4iss0pp35-43.

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In the past, sarooj had been used as the basic cementing material with which the A flaj system (the irrigation system used in Oman) was built. Worldwide, materials like sarooj existed and were known for their good impermeability and long durability. For this reason it was extensively used in hydraulic structures. Even in this century and with the ready availability of Portland cements, special plants were erected to produce materials like sarooj for major dams in the world. In the process of hydration In sarooj-lime mixes or in sarooj-cement mixes free lime is released which causes distress through the expansion of the mortar if allowed to accumulate. If free lime is stabilized within the structure of the mortar. it imparts additional strength and durability to it. The mortar becomes less permeable to water, which increases its resistance to wearhering. The stabilization is possible through the presence of a reactive silica/alumina in the mix so that it reacts with the free lime to form calcium silicates/aluminates. The properties of sarooj depend largely on the type of the raw material and the calcination parameters. This paper describes this material, its method of production and uses, and highlights research currently conducted to improve its properties.

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Miranda, Jean Soares, Ronaldo Luís Almeida de Carvalho, Aline Serrado de Pinho Barcellos, Rodrigo Othávio de Assunção e. Souza, Estevão Tomomitsu Kimpara, and Fabíola Pessôa Pereira Leite. "Different surface treatment protocols of a Y-TZP ceramic with a superficial glaze layer." Brazilian Journal of Oral Sciences 18 (September 9, 2019): e191504. http://dx.doi.org/10.20396/bjos.v18i0.8656589.

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Aim: evaluate the influence of etching time with hydrofluoric acid on the bond strength of a Yttrium-stabilized polycrystalline tetragonal zirconia (Y-TZP) ceramic with a superficial glaze layer and a resin cement. Methods: Y-TZP blocks were cut to obtain 40 samples. They were distributed into four groups (n = 10): control treated by sandblasting with silica-coated alumina (RS) and three glazed experimental groups with different etching times: GS20s, GS60s and GS100s. Cementation was done with a universal adhesive and a resin cement. Two cement cylinders were made in each block. After thermocycling, the shear bond test was performed. Two extra samples of each group were made to obtain profilometry, scanning electron microscopy, mapping and backscattered electron detector images. Energy dispersive spectrometry and goniometry were also performed. Results: Kruskal-Wallis and Dunn tests demonstrated bond strength differences only between the RS (22.10MPa) and the GS groups (GS20s: 8,10Mpa; GS60s: 10.49MPa; GS100s: 7.53MPa) (p = 0.001), but there was no difference among the experimental groups (p > 0.05). The contact angles were 55.33º (RS); 70.78° (GS100s); 48.20º (GS60s) and 28.73º (GS20s). ANOVA and Tukey test demonstrated similar wettability of RS to GS60s and GS100s (p > 0.05), but all the experimental groups were statistically different between them (p < 0.001). Qualitative image analysis revealed an irregular glaze distribution after etching. The thickness of the remaining glaze layer measured by profilometry was 5±1μm (GS20S), 4±1μm (GS60S) and 3±1μm (GS100s). Conclusion: The etching time of glazed zirconia did not influence the adhesive strength of the ceramic to the resin cement.

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Teoreanu, Ion, Gabriela Toma, and Nicolae Toma. "Stabilized Alumina – Silica - Zirconia Refractories within the System Al₂O₃-(Cr₂O₃)-SiO₂-ZrO₂(MO)." Key Engineering Materials 206-213 (December 2001): 1685–88. http://dx.doi.org/10.4028/www.scientific.net/kem.206-213.1685.

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MURRELL, L. "Silica-stabilized aluminas resistant to vanadium attack under severe high-temperature conditions." Journal of Catalysis 111, no. 2 (June 1988): 450–52. http://dx.doi.org/10.1016/0021-9517(88)90108-x.

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29

Franke, Sebastian, Sebastian Beck, Reinhard Caspary, Hans-Hermann Johannes, Annemarie Pucci, and Wolfgang Kowalsky. "Silicon stabilized alumina thin films as gas permeation barriers prepared by spatial atomic layer deposition." MRS Advances 2, no. 17 (2017): 933–38. http://dx.doi.org/10.1557/adv.2017.117.

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ABSTRACTThe growth mechanism and the barrier performance of Al2O3, SiO2 and a binary Si-Al oxide (SiAlxOy) deposited by spatial atomic layer deposition (SALD) were investigated. Alumina and silica were deposited by TMA and BDEAS with growth-per-cycles (GPC) of 0.16 and 0.013 nm, respectively. Interestingly a significant higher GPC of 0.225 nm was found for SiAlxOy. Although alumina in principle has excellent barrier properties, the films easily degraded and lose their barrier performance if exposed to water vapor at elevated temperatures. Therefore, the barrier performances of these films were investigated under harsh environment conditions. We found that the barrier performance of 100 nm Al2O3 failed in less than one day at 70 °C with 70 % relative humidity, whereas 100 nm SiAlxOy sustained for approximately one week. However, the resistivity of those barrier systems was significantly improved by inserting a single 3.3 nm SiO2 layer into the barrier films. In this way the barrier system withstands up to 5 months and the intrinsic water vapor transition rate was reduced by two to three orders of magnitude to ∼10-4 g/m2/day at these tough aging conditions.

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30

Yao, Nan, King Lun Yeung, Guoxing Xiong, and Shishan Sheng. "Genesis and Growth of Nanoparticles during Sol-Gel Synthesis." MRS Proceedings 788 (2003). http://dx.doi.org/10.1557/proc-788-l3.29.

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ABSTRACTIn situ observation of the genesis and growth of silica-alumina structures during the sol-gel process has been carried out. Although the gross structure of the gel network is kinetically stabilized, in situ AFM study reveals that at nanometer scale, the internal structure of the gel is dynamic as shown by the rich and complex morphological transformations.

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31

Evans, N. D., P. H. Imamura, J. Bentley, and M. L. Mecartney. "Characterization of Intergranular Phases in Doped Zirconia Polycrystals." MRS Proceedings 589 (1999). http://dx.doi.org/10.1557/proc-589-383.

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AbstractAnalytical electron microscopy at high spatial resolution in a scanning-transmission mode has been used to investigate the effects of glassy or crystalline material additions on grain boundary chemistry in yttria-stabilized zirconia polycrystals. Powders of additive phase were mixed into 3-mol% yttria-stabilized tetragonal zirconia polycrystals (‘3Y-TZP’) or 8-mol% yttria-stabilized cubic zirconia polycrystals (‘8Y-CSZ’). Zirconias processed without additive phases were also examinedWithout additives, grain boundaries were depleted in zirconium and enriched in yttrium. In 3Y-TZP with I wt% borosilicate glass, silicon was observed only at triple points, but not in grain boundaries. In 3Y-TZP with 1 wt% barium silicate glass, barium was observed both along grain boundaries and at triple points, whereas silicon was detected only within the triple points. This suggests either the composition of the additive phase at the grain boundary is different from that at the triple points, or that barium ions segregate to grain boundaries during processing. In 8Y-CSZ with I wt% silica, silicon was observed in grain boundaries by an EDS spatial differencing technique. In 8Y-CSZ with 10 wt% alumina, EDS revealed aluminum at all grain boundaries examined

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32

Reade, R. P., P. Berdahl, R. E. Russo, and S. M. Garrison. "Biaxially-Textured YBa2Cu3O7–x Thin Film Growth on Polycrystalline and Amorphous Substrates Using Ion Assisted Laser Deposition of Yttria-Stabilized Zirconia Intermediate Layers." MRS Proceedings 285 (January 1, 1992). http://dx.doi.org/10.1557/proc-285-281.

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ABSTRACTThe growth of (001)-textured, biaxially-aligned yttria-stabilized zirconia (YSZ) intermediate layers on amorphous or randomly-oriented polycrystalline substrates is desirable for subsequent YBa2Cu3O7–x (YBCO) c-axis thin film growth. Laser deposition of YSZ on polycrystalline metal substrates (Haynes Alloy #230) in 1.0 millitorr oxygen at 70°C produces partial (001) texture but no alignment of in-plane axes. Highly-textured biaxially-aligned layers are obtained by using an ion beam to assist growth. Similar layers are obtained on amorphous silica and polycrystalline alumina substrates. The effects of ion-beam parameters including incident angle, source gas, and beam voltage and current are presented. Highly c-axis-oriented, biaxiallyaligned YBCO thin films have been deposited in situ on these YSZ layers, with Tc(R=0) ∼ 92K and Jc(77K) = 6 × 105 A/cm2. Angular magnetoresistance data shows a dip in resistance with magnetic field normal to the film, in contrast to films grown epitaxially on single crystal substrates, which have maximum resistance with field normal.

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33

MURRELL, L. L., and N. C. JUN DISPENZIERE. "ChemInform Abstract: Silica-Stabilized Aluminas Resistant to Vanadium Attack Under Severe High-Temperature Conditions." ChemInform 19, no. 36 (September 6, 1988). http://dx.doi.org/10.1002/chin.198836032.

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Xuan Vuong, Bui. "The Evaluation of Formation and Bioactivity of New Sol-gel Bioactive Glass." VNU Journal of Science: Natural Sciences and Technology 35, no. 1 (March 26, 2019). http://dx.doi.org/10.25073/2588-1140/vnunst.4832.

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In this paper, three ceramic compositions 50SiO2-50CaO (A), 45SiO2-45CaO-10P2O5 (B) and 40SiO2-40CaO-20P2O5 (C) (wt %) were synthesized by using the sol-gel technique. XRD analysis demonstrates that only sample C can form the glass material. Treated temperatures and heated times were also evaluated. Analysis data showed that the bioglass 40SiO2-40CaO-20P2O5 (wt %) can successfully elaborate when the ceramic powder heated at 750 oC for 3 hours. ‘‘In vitro’’ experiment was effectuated to investigate the bioactivity of bioglass 40SiO2-40CaO-20P2O5 by soaking powder samples in SBF solution. Obtained result confirmed the formation of hydroxyapatite (HA) phase on glass’s surface after 15 days of immersion, in which HA formation orients following (211) and (222) miller planes in crystalline structure of HA phase. Keywords Sol-gel; bioglass; hydroxyapatite; SBF; bioactivity References [1] D.F. Williams, Definitions in Biomaterials, Consensus Conference for the European Society for Biomaterials, Chester, UK, 1986.[2] L.L. Hench, Bioceramics: From Concept to Clinic, Journal of the American Ceramic Society, 74 (1991) 1487.[3] L.L. Hench, The story of Bioglass, Journal of Materials Science: Materials in Medicine, 17 (2006) 967.[4] X.V. Bui, H. Oudadesse, Y. Le Gal, A. Mostafa, P.Pellen and G. Cathelineau, Chemical Reactivity of Biocomposite Glass-Zoledronate, Journal of the Australian Ceramic Society, 46 (2010) 24.[5] L.L. Hench, Genetic design of bioactive glass, Journal of the European Ceramic Society, 29 (2009) 1257.[6] S. Kumar, P. Vinatier, A. Levasseur, K.J. Rao, Investigations of structure and transport in lithium and silver borophosphate glasses, Journal of Solid State Chemistry, 177 (2004)1723.[7] Z. Hong, A. Liu, L. Chen, X. Chen, X. Jing, Preparation of bioactive glass ceramic nanoparticles by combination of sol–gel and coprecipitation method, Journal of Non-Crystalline Solids, 355 (2009) 368.[8] D.B. Joroch, D.C. Clupper, Modulation of zinc release from bioactive sol–gel derived SiO2‐CaO‐ZnO glasses and ceramics, Journal of Biomedical Materials Research Part A, 82A (2007) 575.[9] J. Roman, S. Padilla, M. Vallet-Regi, Sol−Gel Glasses as Precursors of Bioactive Glass Ceramics, Chemistry of Materials, 15 (2003) 798.[10] J. Lao, J.M. Nedelec, Ph. Moretto, E. Jallot, Biological activity of a SiO2-CaO-P2O5 sol-gel glass highlighted by PIXE-RBS methods, Nuclear Instruments and Methods in Physics Research Section B, 245 (2006) 511.[11] [11] M. Vallet-Regi, L. Ruiz-Gonzalez, I. Izquierdo, J.M. Gonzalez-Calbet, Revisiting silica based ordered mesoporous materials: medical applications, Journal of Materials Chemistry, 16 (2006) 26.[12] W. Xia, J. Chang, Preparation and characterization of nano-bioactive-glasses (NBG) by a quick alkali-mediated sol–gel method, Materials Letters 61 (2007) 3251.[13] R. Li, A.E. Clark, L.L. Hench, An investigation of Bioactive Glass Powders by Sol-Gel Processing, Transactions of 16th Annual Meeting of the Societey for Biomaterials, 12 (1990) 40.[14] J. Lao, J.M. Nedelec, P. Moretto, E. Jallot, Imaging physicochemical reactions occurring at the pore surface in binary bioactive glass foams by micro ion beam analysis, Applied Materials and Interfaces, 6 (2010) 1737.[15] A. Balamurugan, G. Balossier, S. Kannan, J. Michel, A.H.S. Rebelo, J.M.F. Ferreira, Development and in vitro characterization of sol–gel derived CaO–P2O5–SiO2–ZnO bioglas, Acta Biomaterialia, 3 (2007) 255.[16] Z. Hong, A. Liu, L. Chen, X. Chen, X. Jing, Bioactive glass prepared by sol–gel emulsion, Journal of Non-Crystalline Solids, 355 (2009) 368.[17] O. Peital, E.D. Zanotto, L.L. Hench, Highly bioactive P2O5-Na2O-CaO-SiO2 glass-ceramics, Journal of Non-Crystalline Solids, 292 (2001) 115.[18] J. Liu, X. Miao, Sol-gel derived bioglass as a coating material for porous alumina scaffolds, Ceramics International, 30 (2004) 1781.[19] T. Kokubo, H. Takadama, How useful is SBF in predicting in vivo bone bioactivity. Biomaterials 27 (2006) 2907.[20] M. Dziadek, B. Zagrajczuk, P. Jelen, Z. Olejniczak, K.C. Kowalska, Structural variations of bioactive glasses obtained by different synthesis routes, Ceramics International, 42 (2016) 14700.[21] R. Lakshmi, V. Velmurugan and S. Sasikumar, Preparation and Phase Evolution of Wollastonite by Sol-Gel Combustion Method Using Sucrose as the Fuel, Combustion Science and Technology, 185 (2013) 1777.[22] G. Voicu, A. Bădănoiu, E. Andronescu1, C. M. Chifiruc, Synthesis, characterization and bioevaluation of partially stabilized cements for medical applications, Central European Journal of Chemistry, 11 (2013) 1657.[23] M.V. Regi, Ceramics for medical applications, Journal of the Chemical Society, Dalton Transactions, 2 (2001) 97.[24] G. Voicu, A.I. Bădănoiu, E. Andronescu, C.M. Chifiruc, Synthesis, characterization and bioevaluation of partially stabilized cements for medical applications, Central European Journal of Chemistry, 11 (2013) 1657.M. Wu, T. Wang, Y. Wang, F. Li, M. Zhou, X. Wu, A novel and facile route for synthesis of fine tricalcium silicate powders, Materials letters, 227 (2018), 187.

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Journal articles on the topic 'Silica-stabilized alumina'

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