Journal articles: 'Aluwia'

1

MIKUŚ, Paweł, and Alfred UCHMAN. "WPŁYW WEZBRAŃ NA FAUNĘ ZAMIESZKUJĄCĄ ALUWIA NA PRZYKŁADZIE DOLNEGO BIEGU DUNAJCA." Biuletyn Państwowego Instytutu Geologicznego 454, no. 454 (January 1, 2015): 71–76. http://dx.doi.org/10.5604/08676143.1114054.

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Panyathanmaporn, Thammarat, Angkhana Jaroenworaluck, Sitthisuntorn Supothina, Rung-Arun Chumnanklang, Kannikar Juengsuwattananon, Supatra Jinawath, Tawan Sooknoi, Siriya Jiamsakul, and Sittinun Tawkaew. "Ag-Doped TiO₂ Immobilized on Al₂O₃ Bead as Oxidation Catalyst." Materials Science Forum 544-545 (May 2007): 13–16. http://dx.doi.org/10.4028/www.scientific.net/msf.544-545.13.

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Ag-doped TiO2 catalyst employed as the oxidation catalyst candidate was prepared by two methods, co-precipitation and dip coating method. Co-precipitation method was conducted by adding AgNO3 into the titanium precursor before gelation and then the obtained solution was coated on the alumna beads. Dip coating method was conducted by coating the first layer on alumina beads with titanium precursor followed by coating the second layer with AgNO3. The fired Ag-doped TiO2 coated on alumina beads was used as catalyst for catalytic oxidation of methanol and carbon monoxide by using oxygen as oxidizing agent in a gas-phase reactor. The methods of catalyst preparation were found to affect the catalytic efficiency. Dip coating method showed better oxidation reaction as Ag-doped TiO2 catalysts were well dispersed on the alumina beads.

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Kim, W. H., H. J. Lee, Keun Woo Lee, Kwang Mahn Kim, Kyoung Nam Kim, and J. S. Shim. "The Effect of Ceramic Surface Treatments on the Shear Bond Strength of Dental Composite Resin to All-Ceramic Coping Materials." Key Engineering Materials 330-332 (February 2007): 1365–68. http://dx.doi.org/10.4028/www.scientific.net/kem.330-332.1365.

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The purpose of this study was to evaluate the shear bond strength of composite resin to 4 different all-ceramic coping materials with 3 different surface treatments after thermocycling and without thermocycling. Three different surface treatments - sandblasting with 50 ㎛ alumina particles (AB); sandblasting with 50 ㎛ alumina particles and acid etching with 4% hydrofluoric acid (AE); sandblasting with 50 ㎛ alumina particles and 30 ㎛ alumina particles with tribochemical silica coating (SI) and silane application - were used on four different all-ceramic; Feldspatic ceramic (Duceram Plus); Lithium disilicate ceramic (IPS Empress2); Alumica ceramic (In-Ceram Alumina); Zirconia ceramic (Zi-Ceram) - substrates. Shear bond strength of restorative composite resin to substrate was tested after thermocycling and without thermocycling (n=10). Each specimen was subjected to a shear load at a crosshead speed of 2 ㎜/min until fracture. Two-way analysis of variance and Duncan multiple comparison test (α =0.05) were used to analyze the bond strength values. There were significant differences in the bond strengths for ceramic types (P<.001), surface treatments (P<.001), and thermocycling (P<.001). The Duncan analysis showed that the Si specimens had significantly higher bonding strengths than other specimens. The bond strength of composite resin decreased after thermocycling.

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Mahlambi, Mphilisi M., Ajay K. Mishra, Shivani B. Mishra, Rui W. Krause, Bhekie B. Mamba, and Ashok M. Raichur. "TiO2Nanocatalysts Supported on a Hybrid Carbon-Covered Alumina Support: Comparison between Visible Light and UV Light Degradation of Rhodamine B." Journal of Nanotechnology 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/198723.

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Titania nanoparticles were successfully supported on carbon-covered alumina (CCA) supports via the impregnation method to form carbon-covered alumna titania (CCA/TiO2). The CCA supports were synthesised through an equilibrium adsorption of toluene 2,4-diisocyante where the N=C=O irreversibly adsorbs on the alumina and pyrolysis at 700°C affords CCA supports. These CCA/TiO2nanocatalysts were tested for their photocatalytic activity both under UV and visible light using Rhodamine B as a model pollutant. The reaction rate constant of the CCA/TiO2was found to be higher than that of unsupported titania and the reaction kinetics were found to follow an apparent first-order rate law. The CCA/TiO2nanocatalysts had a much larger surface area than the unsupported titania and they exhibited overall higher photodegradation efficiency under both UV and visible light than unsupported TiO2.

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5

Hezil, Naouel, Mamoun Fellah, Ridha Djellabi, Mohamed Zine Touhami, Alex Montagne, Fethia Bouaksa, Alain Iost, Alberto Mejias, and Aleksei Obrosov. "Assessment of the Hydrophilic-Hydrophobic Balance of Alumina Oxidized at Different Temperatures via H₂O and C₄H₁₀ Vapor Adsorption." Defect and Diffusion Forum 397 (September 2019): 161–68. http://dx.doi.org/10.4028/www.scientific.net/ddf.397.161.

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The hydrophilic-hydrophobic surface area of alumina powder (Al2O3) oxidized at different temperatures was determined on the base of adsorption of water and butane vapor at 25°C. In the order to study the influence of thermal oxidation upon hydrophilic/hydrophobic character of the surface, samples of Al2O3 were characterized using granulometry, SEM and BET surface area measurement. SEM results showed that the thermal treatment does not affect the morphology of the Alunima. However, the increase of treatment temperature from 250 to 900°C results in changing of the hydrophilic-hydrophobic balance of Al2O3 surface.

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6

Farhan, Ahmed Jadah. "Effect of Alumina Contents on the Some Mechanical Properties of Alumina (Al2O3) Reinforced Polymer Composites." Neuroquantology 18, no. 5 (May 30, 2020): 35–42. http://dx.doi.org/10.14704/nq.2020.18.5.nq20165.

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7

Jiménez-Piqué, E., L. Ceseracciu, M. Anglada, F. Chalvet, and G. De Portu. "Fatiga por contacto esférico en materiales multicapa de alúmina circona." Boletín de la Sociedad Española de Cerámica y Vidrio 44, no. 5 (October 30, 2005): 307–12. http://dx.doi.org/10.3989/cyv.2005.v44.i5.358.

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8

Quintero, F., J. Pou, F. Lusquiños, M. Boutinguiza, R. Soto, and M. Pérez-Amor. "Corte mediante láser de elementos estructurales de mullita-alúmina." Boletín de la Sociedad Española de Cerámica y Vidrio 45, no. 2 (April 30, 2006): 87–95. http://dx.doi.org/10.3989/cyv.2006.v45.i2.318.

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9

Woźniak, Jarosław, Kamil Broniszewski, Marek Kostecki, Kazimierz Czechowski, Lucyna Jaworska, and Andrzej Olszyna. "Cutting performance of alumina-graphene oxide composites." Mechanik, no. 2 (February 2015): 129/357–129/364. http://dx.doi.org/10.17814/mechanik.2015.2.100.

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10

Zaiter, Haytham Z., Dermot P. Coyne, and James R. Steadman. "Rust Reaction and Pubescence in Alubia Beans." HortScience 25, no. 6 (June 1990): 664–65. http://dx.doi.org/10.21273/hortsci.25.6.664.

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Sixteen Alubia lines (15 with long, straight hairs and one with short, hooked hairs on trifoliolate leaves) derived from single-plant selections made in an Alubia landrace (Argentine) were used to evaluate the relation of abaxial leaf pubescence to reaction to rust in a greenhouse experiment. The pinto cultivar UI-114 (short, hooked hairs) was used as a susceptible check. One plant per pot, replicated six times, in a randomized complete-block design was used. The primary leaves and the sixth trifoliolates of all plants from 12- and 50-day-old plants, respectively, were inoculated with a water suspension of urediniospores (105 cells/ml) of rust isolate US-NP85-10-1. Pustule size and rust intensity were assessed 14 days later. No rust pustules were observed on the sixth trifoliolate leaves of the pubescent (long, straight hairs) Alubia lines, but large pustules were observed on the primary leaves (short, hooked hairs) of all Alubia lines and pinto `UI-114'. as well as on the sixth trifoliolate leaf of A-07-2 and pinto `UI-144' (the latter two with short, hooked hairs).

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11

Lee, Keun-Bong, Seung-Hwa Jung, Ju-Sung Lee, Gyung-Pyo Hong, Bum-Rae Jo, Jong-Su Moon, and Jong-Bong Kang. "Effect of SiO2, Al2O3, and Clay Additions on the Sintering Characteristics of Zircon." Korean Journal of Materials Research 18, no. 7 (July 27, 2008): 352–56. http://dx.doi.org/10.3740/mrsk.2008.18.7.352.

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12

Nakane, Koji, Shinya Ichikawa, Shuya Gao, Mikita Seto, Satoshi Irie, Susumu Yonezawa, and Nobuo Ogata. "Thermal Conductivity of Polyurethane Sheets Containing Alumina Nanofibers." Sen'i Gakkaishi 71, no. 1 (2015): 1–5. http://dx.doi.org/10.2115/fiber.71.1.

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13

Romano, R., J. B. Fogagnolo, A. García, and E. M. Ruiz-Navas. "Sinterización de las aleaciones Alumix 321 y 6061." Revista de Metalurgia 41, no. 1 (February 28, 2005): 21–27. http://dx.doi.org/10.3989/revmetalm.2005.v41.i1.182.

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14

Zhang, Chao, Ling Zhang, Yan An Chang, and Jin Han Liu. "Preparation of β"-Alumina with η Type Nanometer Alumina Powder via Solid Phase Synthesis." Solid State Phenomena 281 (August 2018): 84–89. http://dx.doi.org/10.4028/www.scientific.net/ssp.281.84.

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Beta”-alumina is a fast ion conductor material,it was uesd to prepare a new electrolyte for a secondary energy sodium sulfur battery. nanoeta-alumina has the advantages of high activity and small size,which can reduce the synthesis temperature of beta”-alumina. Beta”-alumina is prepared with Sodium carbonate and eta-alumina amount of substance ratio of 1:5.5 via solid phase synthesis.This paper mainly investigate the temperature on the influence of the content of beta”-alumina and the samples’ crystal structure.The samples were characterized by XRD and SEM.The results show that the mixed powder react to form rhombohedral beta”-alumina at 1100°C;the highest content of beta”-alumina is 87.26% at 1200°C;the beta”-alumina decompose and part of beta”-alumina gradually transform into hexagonal beta-alumina at 1300°C;the content of beta”-alumina reduce and the grain grow at 1400°C; particle of the sample grow irregular and its crystal morphology is incomplete at 1500°C.

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15

Machado, Glauson Aparecido Ferreira, Rosa Maria Rocha, and Ana Helena Almeida Bressiani. "Composites Obtained from Alumina and Polymer Derived Ceramic." Materials Science Forum 912 (January 2018): 141–46. http://dx.doi.org/10.4028/www.scientific.net/msf.912.141.

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Alumina-mullite composites with low shrinkage can be made by reaction bond using mixtures of alumina, aluminum and silicon carbide. In this work, an alternative route is used to produce alumina composites with low shrinkage. Here alumina samples containing additions of 10 and 20 wt% of a preceramic polymer were warm-pressed and treated in the range of 900 -1500°C to produce alumina based composites. The obtained composites were analyzed by linear shrinkage and compared to pure alumina samples sintered at the same temperature range. It were also evaluated the density variation and crystalline phases formed during heat treatment of alumina composites. Results showed that alumina-silicon oxycarbide and alumina-mullite composites were obtained with lower shrinkage than pure alumina samples.

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16

Neville, A. "Instrucción revisada sobre el uso estructural del cemento aluminoso." Materiales de Construcción 55, no. 277 (March 30, 2005): 83–86. http://dx.doi.org/10.3989/mc.2005.v55.i277.182.

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17

Ferrari, C. R., and J. A. Rodrigues. "Aspectos microestructurales de los refractarios con alúmina conteniendo agregados de MullitaâCircona." Boletín de la Sociedad Española de Cerámica y Vidrio 42, no. 1 (February 28, 2003): 15–20. http://dx.doi.org/10.3989/cyv.2003.v42.i1.651.

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18

Yiyu Shen, Yiyu Shen, Dun Liu Dun Liu, Wei Zhang Wei Zhang, Geof f. Dearden Geof f Dearden, and Ken Watkins Ken Watkins. "Ultrafast laser surface wettability modif ication on alumina surface." Chinese Optics Letters 11, no. 2 (2013): 021403–21405. http://dx.doi.org/10.3788/col201311.021403.

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19

HOSEINI, S. Mehdi, and Javad AKBARI. "3334 Taguchi's Optimization in Ultrasonic Drilling of Alumina Ceramic." Proceedings of International Conference on Leading Edge Manufacturing in 21st century : LEM21 2011.6 (2011): _3334–1_—_3334–4_. http://dx.doi.org/10.1299/jsmelem.2011.6._3334-1_.

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20

Tamásné Csányi, Judit, and László A. Gömze. "Impact of nitrogen atmosphere on sintering of alumina ceramics." Epitoanyag - Journal of Silicate Based and Composite Materials 60, no. 1 (2008): 15–18. http://dx.doi.org/10.14382/epitoanyag-jsbcm.2008.4.

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21

Csányi, Judit. "Rheological characteristics of alumina powders in dry pressing technology." Epitoanyag - Journal of Silicate Based and Composite Materials 61, no. 1 (2009): 6–10. http://dx.doi.org/10.14382/epitoanyag-jsbcm.2009.2.

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22

Dutra Golanda, Alexandre, Sandro Galisteu Luiz, Katia C. Gandolpho Candioto, and Carlos Yujiro Shigue. "Preparation and Test of Conventional Composite Abrasives Using Recycled Alumina Grains." Materials Science Forum 874 (October 2016): 199–204. http://dx.doi.org/10.4028/www.scientific.net/msf.874.199.

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In this work we report the preparation and evaluation of the mechanical characteristics of resin-bond composite abrasives using virgin and recycled alumina grains. The composite abrasives were made with phenolic resin as binder and as-received virgin and recycled alumina grains. Three different recycled alumina grains were studied: i) alumina from wood firing resin-bond abrasive tools; ii) alumina from wood firing vitrified-matrix abrasive tools; and iii) ground alumina from vitrified-matrix abrasive tools. The virgin alumina grains were employed in order to compare the mechanical performance of the prepared composite abrasive. The composition of alumina grains, analyzed by X-ray fluorescence spectroscopy revealed the recycled alumina grains have lower alumina content and higher concentration of silica in vitrified-matrix abrasives samples. The sand blast penetration tests have shown lower penetration depth in the virgin and the ground vitrified-matrix grains composites. The impact strength test results revealed its dependence on the alumina and silica content: samples with higher alumina content present the higher impact resistance whereas samples with higher silica content present lower impact strength.

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23

Affatato, S., F. Traina, M. De Fine, S. Carmignato, and A. Toni. "Alumina-on-alumina hip implants." Journal of Bone and Joint Surgery. British volume 94-B, no. 1 (January 2012): 37–42. http://dx.doi.org/10.1302/0301-620x.94b1.26956.

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24

Garcia-Cimbrelo, Eduardo, Eduardo Garcia-Rey, Antonio Murcia-Mazón, Agustín Blanco-Pozo, and Eduardo Martí. "Alumina-on-Alumina in THA." Clinical Orthopaedics and Related Research 466, no. 2 (January 10, 2008): 309–16. http://dx.doi.org/10.1007/s11999-007-0042-1.

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25

Chen, Liang-Yu. "Dielectric Performance of a High Purity HTCC Alumina at High Temperatures - A Comparison Study with other Polycrystalline Alumina." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2014, HITEC (January 1, 2014): 000271–77. http://dx.doi.org/10.4071/hitec-wp26.

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A very high purity (99.99+%) high temperature co-fired ceramic (HTCC) alumina has recently become commercially available. The raw material of this HTCC alumina is very different from conventional HTCC alumina, and more importantly there is no glass additive in this alumina material for co-firing processing. Previously, selected HTCC and LTCC (low temperature co-fired ceramic) alumina materials were evaluated at high temperatures as dielectric and compared to a regularly sintered 96% polycrystalline alumina (96% Al2O3), where 96% alumina was used as the benchmark. A prototype packaging system based on regular 96% alumina with Au thick-film metallization successfully facilitated long term testing of high temperature silicon carbide (SiC) electronic devices for over 10,000 hours at 500°C. In order to evaluate this new high purity HTCC alumina for possible high temperature packaging applications, the dielectric properties of this HTCC alumina substrate were measured and compared with those of 96% alumina and a previously tested LTCC alumina from room temperature to 550°C at frequencies of 120 Hz, 1 KHz, 10 KHz, 100 KHz, and 1 MHz. A parallel-plate capacitive device with dielectric of the HTCC alumina and precious metal electrodes were used for measurements of the dielectric constant and dielectric loss of the co-fired alumina material in the temperature and frequency ranges. The capacitance and AC parallel conductance of the capacitive device were directly measured by an AC impedance meter, and the dielectric constant and parallel AC conductivity of the dielectric were calculated from the capacitance and conductance measurement results. The temperature and frequency dependent dielectric constant, AC conductivity, and dissipation factor of the HTCC alumina substrate are presented and compared to those of 96% alumina and a selected LTCC alumina. Other technical advantages of this new co-fired material for possible high packaging applications are also discussed.

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Yang, Sheng-Tao, Tiancheng Wang, Erya Dong, Xin-Xin Chen, Kun Xiang, Jia-Hui Liu, Yuanfang Liu, and Haifang Wang. "Bioavailability and preliminary toxicity evaluations of alumina nanoparticles in vivo after oral exposure." Toxicology Research 1, no. 1 (May 22, 2012): 69–74. http://dx.doi.org/10.1039/c2tx20008b.

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Abstract Alumina nanoparticles (NPs) are among the most important nanomaterials and are widely used in diverse areas. In this study, we evaluated the bioavailability and toxicity of alumina NPs in mice after oral exposure, compared with traditional alumina powder. Our results indicated that negligible alumina NPs were absorbed post-exposure and alumina NPs did not influence the balance of essential trace elements, including Fe, Cu and Zn. Preliminary toxicological evaluations suggested that alumina NPs were of low toxicity. The body weights were similar among the mice exposed to alumina NPs, alumina powder and 0.9% NaCl aqueous solution. The low toxicity was also indicated by the unchanged serum biochemical parameters. The implications related to the ongoing safety evaluations and applications of alumina NPs are discussed.

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27

XU, JIE, WEI LIU, GUO-AN CHENG, and RUI-TING ZHENG. "SYNTHESIS AND OPTICAL PROPERTIES OF LARGE-SCALE ALIGNED ALUMINA NANOWIRE ARRAYS." Modern Physics Letters B 24, no. 02 (January 20, 2010): 151–60. http://dx.doi.org/10.1142/s0217984910022330.

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Ordered large-scale alumina nanowire arrays on the surface of porous anodic alumina membranes (AAMs) have been synthesized by chemical etching. The analysis shows that amorphous alumina nanowires directly formed from AAMs have uniform size and shape. The mean length and mean diameter of alumina nanowires are about 6 μm and 24 nm, respectively. It is observed that chemical etching parameters affect the synthesis of alumina nanowires and preferable experimental conditions for the synthesis of alumina nanowire arrays. The intensity of photoluminescence excited from alumina nanowire is affected by post-annealing temperatures. The mechanisms for the synthesis and PL emission of alumina nanowires are discussed.

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28

Hashimoto, R. Y., E. S. K. Menon, and A. G. Fox. "Segregation of Silicon in Metal-Alumina Composites." Microscopy and Microanalysis 5, S2 (August 1999): 624–25. http://dx.doi.org/10.1017/s1431927600016445.

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A common impurity in polycrystalline commercial alumina is Si since silica is often added as a sintering aid. There have been several studies on impurities in alumina, and substantial degree of grain boundary segregation has been found to occur. Alumina-metal composites have found several applications especially in the electronic industry and consequently systems such as alumina-copper have been studied exhaustively. However, the role of impurities in metal-alumina composites has not been fully explored. Studies of Pt-alumina composites has shown that silicon is present at the interface of vacuum, diffusion bonded samples. Our earlier studies have shown that Si indeed segregates to the triple junctions and grain boundaries in alumina and in alumina-copper composites, often Si segregates to the metal-ceramic interfaces as well. This investigation concentrates on the distribution of silicon in copper-alumina in comparison to aluminum-alumina composites.The metal-ceramic composites were prepared by diffusion bonding 99.99% pure metal foils sandwiched in between commercially available sintered alumina (∼99.5% pure) substrates for several hours in vacuum.

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29

Kelly, J. D., G. L. Hosfield, G. V. Varner, M. A. Uebersax, and J. Taylor. "Registration of ‘Beluga’ Alubia Bean." Crop Science 39, no. 1 (January 1999): 294. http://dx.doi.org/10.2135/cropsci1999.0011183x003900010065x.

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30

Martynenko, V. V., Yu A. Krakhmal, K. I. Kushchenko, and T. G. Tishina. "Properties dependence of the lightweight alumina products obtained by a semi-dry pressing method on the alumina type." Scientific research on refractories and technical ceramics 120 (December 30, 2020): 126–33. http://dx.doi.org/10.35857/2663-3566.120.12.

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Lightweight materials are widely used in industry for thermal insulation of various thermal units. The choice of lightweight material depends on the specific conditions of service. For the lining of high-temperature units operating in reducing environments, alumina lightweight products are used that contain a minimum amount of Fe2O3 impurities and free (unbound in compounds) SiO2. In JSC “URIR named after A. S. Berezhnoy” a technology of alumina lightweight products of grades KLA-1.1 and KLA-1.3 by a semi-dry pressing method with an application temperature of up to 1550 °C has been developed. These products are made from a mixture of ground and no-milled γ-form alumina of grade 0 and α-form alumina of grade S with additives of pitch coke and chalk. The work purpose was improvement of the alumina lightweight products technology and search for new alternative raw materials along with the currently used alumina grade S. The properties dependence of alumina lightweight products, obtained by the semi-dry pressing method, on the type of alumina α-form, was investigated. As a result of the studies, it was found that, for the manufacture of alumina lightweight products of grades KLA-1.1 and KLA-1.3 by the semi-dry pressing method, alumina grades N and NR can be used as an alternative alumina-containing raw material along with alumina grade S. The phase composition of alumina lightweight products of grades KLA-1.1 and KLA-1.3, which are manufactured using alumina grades S, N and NR, was represented mainly by corundum and calcium hexaluminate. The alumina lightweight products, which were manufactured using alumina grades S, N and NR, were characterized by similar high properties and correspond the technical requirements for grades KLA-1.1 and KLA-1.3.

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Liu, Xiao Ting, Bao Dong Wang, Yong Feng Xiao, Xiao Huan Wang, Li Jun Zhao, Geng Zhi Yu, and Qi Sun. "Alumina Extraction from Alumina Rich Fly Ash Generated from Inner-Mongolia Chinese Coal." Advanced Materials Research 1065-1069 (December 2014): 1725–31. http://dx.doi.org/10.4028/www.scientific.net/amr.1065-1069.1725.

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Generated during the combustion of coal for electricity production, fly ash is a solid waste and causes great ecomomic burden and serious environmental pollution. On the other hand, it is a good resource for the preparation of industrial products. Especially, alumina rich fly ash from Inner-Mongolia Guohua Junggar Power Plant typically contains 45-55% alumina, 30-40% silica, and 5-10% other metallic oxides, it is a perfect resource for alumina extraction. In order to improve the utilization value of alumina rich fly ash and lessen environmental strain, a novel approach for alumina extraction from alumina rich fly ash was proposed. The proposed process includes a pre-desilication process, soda lime sintering process, dissolving process, carbonation process and calcination process. The technological conditions for alumina extraction from Junggar alumina rich fly ash were optimized by means of orthogonal experment design. The extraction rate of alumina was 96%. Value-added products, such as electrolytic grade alumina and white carbon black, were produced at the same time.

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Momohjimoh, Ibrahim, Mohamed Hussein, and Nasser Al-Aqeeli. "Recent Advances in the Processing and Properties of Alumina–CNT/SiC Nanocomposites." Nanomaterials 9, no. 1 (January 11, 2019): 86. http://dx.doi.org/10.3390/nano9010086.

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An alumina-based nanocomposite is fabricated through the addition of secondary nanophase material to an alumina matrix to alter and tailor the properties of alumina. The addition to alumina of semi-conductive materials, such as silicon carbide (SiC), and high conductive materials, such as carbon nanotubes with a characteristic size in the nanometer range, can alter the mechanical strength, hardness, toughness, and electrical and thermal properties of alumina. This paper discusses recent advances in the synthesis of alumina–SiC and alumina-carbon nanotube (CNT) nanopowders and their consolidation using conventional and non-conventional techniques. Mechanical (hardness, fracture toughness and flexural strength) and functional (thermal and electrical) properties are discussed. The influence of the microstructure on the properties of alumina–SiC and alumina–CNT nanocomposites is discussed. Furthermore, potential applications and current related research trends are described.

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33

Ulfah, Maria, and Subagjo Subagjo. "PENGARUH PERBEDAAN SIFAT PENYANGGA ALUMINA TERHADAP SIFAT KATALIS HYDROTREATING BERBASIS NIKEL-MOLIBDENUM." Reaktor 14, no. 2 (September 4, 2012): 151. http://dx.doi.org/10.14710/reaktor.14.2.151-157.

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EFFECT OF ALUMINA SUPPORT PROPERTIES ON THE NICKEL-MOLIBDENUM BASE HYDROTREATING CATALYST. Effect of surface characteristics of three species of synthesized γ-alumina (alumina-1, alumina-2 and alumina-3) on characteristics NiMo catalysts has been studied. Those aluminas are derived from boehmite Catapal B by varying rasio mol nitric acid to boehmite. A sol-gel method is used to synthesize γ-Al2O3 support. The Nitrogen adsorption, X-ray diffraction (XRD), Temperature Programmed Reduction (TPR) of H2, Temperature Programmed Desorption (TPD) of NH3, and mechanical strength are used to characterize the supports and catalysts. The results showed that the surface area alumina affects the formation of crystalline MoO3 in the NiMo catalyst, while γ-Al2O3-3 support which has the highest surface area (about 195 m2/g) compared to the other two types of alumina (>195 m2/g) does not have a crystalline MoO3. The formation of crystalline MoO3 is not influenced by the acidity alumina. Based on the results of XRD, it is indicated that the supported alumina-3 NiMo catalyst (having the highest acid strength) shows that there is no presence of crystalline MoO3. Pore size distribution of support did not change significantly after the deposition of Ni and Mo oxides. Mechanical strength of support also affects the strength NiMo catalyst. Support alumina-3 which has the highest mechanical strength gives the mechanical strength of the highest NiMo catalyst. Pengaruh sifat penyangga γ-alumina hasil pengembangan (alumina-1, alumina-2 dan alumina-3) pada karakter katalis hydrotreating nikel-molibdenum (NiMo) telah dipelajari. Ketiga jenis γ-alumina diturunkan dari boehmite “Catapal B” dengan menvariasikan nisbah mol asam nitrat terhadap boehmite. Pembuatan γ-alumina menggunakan metoda sol-gel. Adsorpsi Nitrogen, X-ray difraksi (XRD), Temperature Programmed Reduction (TPR) H2, Temperature Programmed Desorption (TPD) NH3, dan kekuatan mekanik digunakan untuk mengkarakterisasi penyangga dan katalis. Hasil penelitian menunjukan bahwa luas permukaan alumina mempengaruhi pembentukan kristalin MoO3 dalam katalis NiMo. Pada penyangga alumina-3 yang memiliki luas permukaan yang paling tinggi (sekitar 195 m2/g) di banding dua jenis alumina lainnya (>195 m2/g) tidak memiliki kristalin MoO3. Pembentukan kristalin MoO3 tidak dipengaruhi oleh sifat keasaman alumina. Berdasarkan hasil XRD ditunjukan bahwa pada katalis NiMo berpenyangga alumina-3 (memiliki kekuatan asam yang paling tinggi) tidak terdapat adanya kristalin MoO3. Distribusi ukuran pori peyangga tidak berubah signifikan setelah deposisi oksida Ni dan Mo. Kekuatan mekanik penyangga mempengaruhi pula kekuatan katalis NiMo. Penyangga γ Al2O3-3 yang memiliki kekuatan mekanik yang paling tinggi memberikan kekuatan mekanik katalis NiMo yang tertinggi.

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Mizushima, Yasuyuki, and Makoto Hori. "Preparation of heat-resistant alumina aerogels." Journal of Materials Research 8, no. 11 (November 1993): 2993–99. http://dx.doi.org/10.1557/jmr.1993.2993.

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Alumina aerogels were prepared using supercritical drying methods, and their thermal properties were examined. The effects of several additives to the alumina aerogel and supercritical drying methods were examined in order to improve heat resistance. Silica, phosphoric oxide, barium oxide, lanthanum oxide, and SiC whisker were effective for maintaining a high specific surface area of the alumina aerogel at a temperature over 1200 °C. Silica was found to be the most effective among the additives. The addition of 10 mol % silica resulted in an alumina aerogel with the highest specific surface area, 114.3 m2/g at 1200 °C, and increased the transformation temperature to α alumina. Barium oxide and lanthanum oxide formed smaller crystals within the alumina, compared with those of alumina alone. SiC whisker caused many cracks in the alumina aerogel. When supercritically dried, the alumina aerogel was strengthened by treatment at higher temperature and pressure.

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Han, Ming Rong, Jian Guo Yin, and Long Qiang Huang. "Dissolution of Alumina in Molten Aluminum Electrolyte Based on Perforated Anode." Advanced Materials Research 941-944 (June 2014): 13–17. http://dx.doi.org/10.4028/www.scientific.net/amr.941-944.13.

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To solve the problem of alumina dissolution in perforated anode technology, dissolution behavior of alumina has been studied in the laboratory by simulating electrolyte parameters of the factory which has adopted the technology. The results show that alumina saturated solubility is 3.991% for system at 940°C. The relationship between dissolution rate and concentration of alumina does not have regular change when alumina concentration is less than about 1%. When the concentration is greater than about 1%, the dissolution rate declines with the increasing concentration of alumina. Combined with the production, the suggestions which can improve energy-saving effect are proposed as follows: the particle size and the concentration of alumina in the electrolyte should be controlled in the range of 44μm to 100μm and 1.5% to 3% respectively; the time interval of point loading and the alumina supply every time can be cut down properly and alumina can be preheated.

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36

Leela-adisorn, Uraiwan, Takuya Matsunaga, Seong Min Choi, Sawao Honda, and Hideo Awaji. "Alumina-Based Nanocomposites Fabricated by a Novel Soaking Method." Key Engineering Materials 317-318 (August 2006): 607–10. http://dx.doi.org/10.4028/www.scientific.net/kem.317-318.607.

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Nickel dispersed alumina matrix nanocomposites were fabricated using a novel soaking method. Secondary particles were introduced into the nano-pores of a porous matrix grains by a soaking method, such that γ-alumina powder was soaked in nickel nitrate solution under vacuum. During pre-calcination, nickel oxide particles were created inside of the nano-pores of γ-alumina. The alumina powders were then reduced under hydrogen atmosphere to obtain nano-sized metallic nickel embedded in γ-alumina grains. The alumina-nickel composite powders were sintered by pulse electric current sintering (PECS) technique with α-alumina seeds. The maximum strength of the alumina-nickel nanocomposites was 984 MPa after sintering at 1,450 °C with α-alumina seeds, where the specimen size was 2210 mm3. The maximum fracture toughness was 5.5 MPa·m1/2 after sintering at 1,350 °C with seeds measured by the single edge V-notched beam (SEVNB) method.

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37

Yang, S. H., and S. Kang. "Fracture behavior and reliability of brazed alumina joints via Mo–Mn process and active metal brazing." Journal of Materials Research 15, no. 10 (October 2000): 2238–43. http://dx.doi.org/10.1557/jmr.2000.0321.

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Alumina/alumina and alumina/kovar/alumina joints were produced via two joining techniques: (i) a moly-manganese process and (ii) active metal brazing. These joints were heat treated at 400 °C for 100 h to evaluate their fracture strength, fracture behavior, and high-temperature reliability. Depending on the joining methods employed, the optimum microstructure of ceramics for joining is different. It was found in most cases, that the active metal brazing resulted in superior joint strength and reliability over the moly-manganese process. The fracture strength and reliability of alumina/kovar/alumina joints were lower than those of alumina/alumina joints and showed different fracture behaviors. After heat treatment, fracture strength and reliability decreased due to the formation of brittle phases at the joint interface. The fraction of brittle debonding at the interface increased with heat treatment, while that of fracture within the alumina decreased.

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Tang, Hai, Yingheng Shi, and Wenjie Yuan. "Influence of powder characteristics on the sintering behaviour of reactive alumina powders." Processing and Application of Ceramics 16, no. 1 (2022): 1–6. http://dx.doi.org/10.2298/pac2201001t.

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Fine reactive alumina powders have a significant impact on the properties of refractories at high temperatures. Except for the hydration of cement and in situ reactions, the performance of castables is also correlated with the sintering of reactive alumina. The characteristics of fine alumina powders produced by various manufacturers are quite different. This work aims to investigate the comprehensive influence of powder characteristics on the sintering behaviour of reactive alumina powders. Three types of commercial reactive alumina powders were selected for experiments. The linear shrinkage, bulk density, apparent porosity and microstructure of alumina compacts calcined at different temperatures were analysed. It was demonstrated that large specific surface area and higher SiO2 content had a positive effect on the densification of alumina compacts. The calculation based on the hypothetical composition of alumina grain boundary indicated that SiO2 mainly participated in the formation of liquid. Therefore, more liquid was generated at the grain boundary of alumina grains containing higher SiO2 content, which resulted in better sinterability of reactive alumina powders.

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39

Hemanth Kumar, G., and B. Ajitha. "Prediction of Compressive Strength of Nano Alumina, Micro Alumina & Fly Ash Blended with Cement by Using Coefficient of Correlation." Asian Review of Civil Engineering 9, no. 2 (November 5, 2020): 8–11. http://dx.doi.org/10.51983/tarce-2020.9.2.2557.

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In this research study, the effect on High Strength Concrete (HSC) by partial replacement of cement with Nano alumina, micro alumina and fly ash on the mechanical properties of the concrete is studied. In this investigation the cement is replaced by 20% Fly ash, 5% micro alumina and nano alumina of different proportion i.e., 0.25%, 0.5%, 0.75%, 1% in M60 grade of concrete. It is observed that the concrete's workability is reduced by increasing the content of nano alumina from 0% to 1% and constant micro alumina particles of 5% cement (by Wt.) and fly ash of 20% cement (by wt.). The results showed that 0.75% of the combination of nano alumina, micro alumina and fly ash increases the properties of the high strength concrete. The microstructure characteristics results revealed that the Nano alumina, micro alumina and fly ash particles incorporated enhances the cement's mechanical strength properties and the voids were filled up with these materials. The present investigation is mainly focused on reliability assessment to the High Strength Concrete by using by using Karl Pearson’s correlation coefficient.

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40

Kobayashi, Yoshio, Yusuke Mabuchi, Masachika Hama, Katsumi Yamamura, Yusuke Yasuda, and Toshiaki Morita. "Effects of Seeding with Nanocrystallites and Addition of Inorganic Alumina Sol on Crystallization of Alkoxide Alumina Gel." Key Engineering Materials 697 (July 2016): 12–17. http://dx.doi.org/10.4028/www.scientific.net/kem.697.12.

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This paper reports a method for producing α-Al2O3 at low temperature from aluminum alkoxide using a combination of seeding of α-Al2O3 nanocryatallites and adding of inorganic alumina sol. An alkoxide alumina sol was obtained by hydrolyzing aluminum isopropoxide in water at 80°C and then peptizing the hydrolyzed aluminum isopropoxide using acetic acid at 80°C. An inorganic alumina sol was obtained by producing aluminum compound with a homogeneous precipitation method using aluminum nitrate and urea in aqueous solution and then peptizing the aluminum compound using acetic acid at room temperature. α-Al2O3 nanocrystallites were added to the alkoxide alumina sol containing the inorganic alumina sol. The addition of inorganic alumina sol provided successful fabrication of a crack-free α-Al2O3-seded alumina film by a spin-coating technique. The sol containing α-Al2O3 nanocrystallites was transformed to an α-Al2O3-seeded alumina gel by drying the sol at room temperature. The non-seeded alumina gel was crystallized into γ-Al2O3 at a temperature below 900°C. In contrast, the alumina seeded at 1% α-Al2O3 nanocrystallites content began to be transformed to α-Al2O3 by annealing at the temperature. The seeding and the adding promoted crystallization of the alumina gel into α-Al2O3. The promotion of crystallization was significant with an increase in α-Al2O3 nanocrystallites content by weight in the final seeded alumina gel.

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Ben, Hasan, Marija Dimitrijevic, Aleksandar Kojovic, Dusica Stojanovic, Kosovka Obradovic-Djuricic, Radmila Jancic-Heinemann, and Radoslav Aleksic. "The effect of alumina nanofillers size and shape on mechanical behavior of PMMA matrix composite." Journal of the Serbian Chemical Society 79, no. 10 (2014): 1295–307. http://dx.doi.org/10.2298/jsc140121035b.

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Composites with the addition of alumina nanofillers show improvement in mechanical properties. The PMMA polymer was used as a matrix and two different types of nanofillers, having extremely different shapes were added in the matrix to form the composite. Reinforcements were based on alumina nanoparticles having either spherical shape or whiskers having the length to diameter ratio of 100. The influence of alumina fillers size, shape and fillers loading on mechanical properties of prepared composite were studied using the nanoindentation measurements and dynamic mechanical analysis. It was observed that both alumina whiskers and alumina spherical nanoparticles added in the PMMA matrix improved the mechanical properties of the composite but the improvement was significantly higher with alumina whisker reinforcement. The concentration of the reinforcing alumina spherical nanoparticles and alumina whiskers in PMMA matrix varied up to 5 wt. %. The best performance was obtained by the addition of 3 wt. % of alumina whiskers in the PMMA matrix with regard to mechanical properties of the obtained composite.

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Su, B., X. He, S. Dhara, and J. P. Mansell. "Porous and Bioactive Alumina Ceramics for Bone Grafts and Tissue Engineering Scaffolds." Key Engineering Materials 330-332 (February 2007): 975–78. http://dx.doi.org/10.4028/www.scientific.net/kem.330-332.975.

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An environmentally friendly direct foaming method was investigated to produce porous alumina ceramics. Egg white protein was used as a binder and foaming agent. The microstructures show that pores are interconnected with pore size of a few hundreds μm and pore window size of ca. 50 μm. The compressive strength of alumina foam is up to 100 MPa depending on porosity. Bioactivation of alumina was carried out using an alkaline solution treatment. Hydroxylation of alumina was achieved using 5M NaOH at 80°C for 4 days. In vitro assessments of the alumina in a human osteoblast cell-like cell (MG63) culture showed that the bioactivated alumina foams exhibited better cellularity and alkaline phosphatase (ALP) activity compared to untreated alumina foams. The results indicate that it is possible to improve the osseointgration of alumina ceramics by structural and surface modifications and to extend the applications of biocompatible alumina ceramics in biomedical implants and tissue engineering scaffolds.

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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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44

Limpichaipanit, Apichart, Sukanda Jiansirisomboon, and Tawee Tunkasiri. "Sintering temperature-microstructure-property relationships of alumina matrix composites with silicon carbide and silica additives." Science and Engineering of Composite Materials 24, no. 4 (July 26, 2017): 495–500. http://dx.doi.org/10.1515/secm-2014-0353.

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AbstractAlumina-based composites were fabricated by reaction sintering from two different sintering powder mixtures: alumina with silica (SiO2) and alumina with silicon carbide (SiC; to allow oxidation to form SiO2). After sintering, SiO2 underwent complete reaction to form alumina/mullite composites. In terms of microstructure, the density and grain size of ceramic samples were investigated. The density of the composites prepared by alumina and SiC was lower than those of alumina and the composites prepared by alumina and SiO2. The grain size increased as the sintering temperature increased. In terms of mechanical properties, fracture surfaces, hardness, and fracture toughness were investigated. It was found that the fracture surface of alumina was rather intergranular, whereas the fracture surface of the composites was more transgranular. The hardness of the composites was higher than that of alumina at the same sintering temperature. However, the fracture toughness of the composites was not significantly different compared to that of alumina.

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Lee, Chung Hyo, Young Sup Lee, Dong Choul Cho, and Chang Hee Lee. "Microstructure and Mechanical Properties of DBC on Sputter Deposited Copper on Alumina Substrate." Materials Science Forum 449-452 (March 2004): 677–80. http://dx.doi.org/10.4028/www.scientific.net/msf.449-452.677.

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The process of Direct Bonding Copper (DBC) is performed by a spinel reaction between CuO and Al2O3. In order to develop DBC on alumina substrate with high bonding strength, alumina substrate was preformed as follows: Cu was sputter-deposited on alumina substrate. Sputter-Deposited Cu (SDC) on alumina substrate was oxidized at 673K for 30min in air atmosphere and then stabilized at 1273K for 30min in N2 gas atmosphere to improve bonding strtrength between preformed alumina substrate and SDC layer. Subsequently, the Cu-foil (300µm) was bonded on preformed-alumina substrate in N2 gas atmosphere at 1342~1345K. It was found that optimum condition of DBC on preformed-alumina substrate could be successfully obtained at 1345K for 30min. Consequently, bonding strength of DBC on alumina substrate was the high value of 80N/cm. Observation and analysis of microstructure for Cu sputtered DBC showed that reaction compounds such as CuAlO2 and CuAl2O4 approved to be formed in the vicinity of interface between Cu and alumina substrate.

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46

Mizumoto, Masayuki, Takeshi Ohgai, and Akio Kagawa. "Effect of Alumina Fibers on Fabrication Process and Characteristics of Alumina Fiber Reinforced Aluminum Alloy Composites." Materials Science Forum 638-642 (January 2010): 956–60. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.956.

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In order to develop the alumina fiber reinforcements optimized to FRMMCs, the effect of characteristics of alumina fibers on the fabrication process and the characteristics of the alumina fiber reinforced Al alloy composites was investigated. Alumina fibers which have different alumina content were prepared. Alumina content in the fibers was varied from 80% to 100%. Al-4mass%Cu alloy, Al-12mass%Si alloy and Al-10masss%Mg alloy were used as matrix. The FRMMC specimens were fabricated by a low-pressure infiltration process (LPI process). The formability of the preform was improved with increasing alumina content in the fibers. However, broken fibers were observed in the preform when alumina fibers with high alumina content were used. The number of the broken fibers seemed to be increased with increasing alumina content in the fibers. This result could be attributable to a change of fiber strength resulting from a change of alumina content in the fiber. The FRMMC specimens were characterized by using Vickers hardness test. The Vickers hardness of FRMMC specimens depended on the elasticity or the hardness of the fibers. The results obtained suggest that the characteristics of the FRMMCs largely depend on the intrinsic characteristics of the reinforcement fibers.

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Wallenberger, F. T., N. E. Weston, and S. A. Dunn. "Inviscid melt spinning: As-spun crystalline alumina fibers." Journal of Materials Research 5, no. 11 (November 1990): 2682–86. http://dx.doi.org/10.1557/jmr.1990.2682.

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Inviscid melt spinning yielded the first crystalline alumina fibers directly from the melts. In this experimental process, a liquid jet having a melt viscosity of <101 poise (vs>104 for fiberglass) is extruded into propane and is thus chemically stabilized (vs rapidly quenched) before it forms Rayleigh waves and breaks up into droplets. This letter describes a 65.5% alumina-zirconia fiber, an 81.5% and a 90.6% alumina-calcia fiber, a 98.6% alumina-magnesia fiber, and a 100% alumina fiber. The δ-allomorph was identified as the crystalline phase of the melt spun 100% alumina fibers, compared to the α-allomorph reported for FIBER FP, a slurry spun and sintered 100% alumina fiber.

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Susnitzky, David W., and C. Barry Carter. "The formation of copper aluminate by solid-state reaction." Journal of Materials Research 6, no. 9 (September 1991): 1958–63. http://dx.doi.org/10.1557/jmr.1991.1958.

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Solid-state reactions between bulk samples of copper oxide and alumina have been studied using scanning electron microscopy and electron microprobe analysis. Both CuAl2O4 and CuAlO2 were found to form during reactions in air at 1100 °C between CuO powder and single-crystal alumina substrates. The relative position of the CuAl2O4 and CuAlO2 layers was observed to depend on the crystallographic orientation of the surface of the alumina substrate: CuAl2O4 formed in contact with (0001) alumina substrates while CuAlO2 formed when the alumina substrate surface was (110). Faceted Cu–aluminate/alumina phase boundaries were observed to develop when single-crystal alumina rods were reacted with CuO, although the interfaces invariably tended to be wavy.

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Ge, Xing Ze, Qi Ge, Xing Shuo Ge, Deng Hui Ji, Ying Huang, Zhong Lun Zhang, and Hong Bo Zhang. "Influence of La₂O₃ Addition on Microstructure and Mechanical Properties of Al₂O₃ Ceramics." Materials Science Forum 956 (June 2019): 69–77. http://dx.doi.org/10.4028/www.scientific.net/msf.956.69.

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In this paper, alumina ceramics were prepared with alumina powder and lanthanum nitrate. The influence of La2O3 on the microstructure and properties of alumina ceramics were studied. The result showed that the addition of La2O3 contributed to the mechanical property of the samples. The alumina ceramics with adding of 0.05wt% La2O3 sintered at 1490°C had the best mechanical properties. And the flexural strength, fracture toughness of the ceramics could reach 571.902MPa and 5.82MPa•m1/2，which were improved by 37.55% and 10.65% respectively compared with the alumina ceramics without La2O3. Besides, the average grain size of alumina ceramic is about 2.8μm, and the effect of inhibition on grain growth of alumina ceramics was obvious.

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50

Liang, Yan Yuan, Da Ming Chen, Jian Feng Tong, and Xian Cong Huang. "Preparation of Integrated Ceramic Armor for Body Bulletproof by Semi-Aqueous Gel-Casting." Advanced Materials Research 105-106 (April 2010): 782–86. http://dx.doi.org/10.4028/www.scientific.net/amr.105-106.782.

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Arc-shaped integrated alumina ceramic armor for body bulletproof with the size of 300 × 250 × 6 mm, R400mm were prepared by semi-aqueous gel-casting. The excellent characters and advantages of the semi-aqueous gel-casting were analyzed; ballistic experiments were carried out to test the protection coefficient of 92%, 96%and 99 alumina ceramics. The experimental results showed that the 92% alumina ceramic and the 99% alumina ceramic had favorable performance while the 96% alumina ceramic had the worst one. But the 92% alumina ceramic had the highest protection coefficient which is 9.96.

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Journal articles on the topic 'Aluwia'

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