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Sample records for aluminia

  1. Characterization and sintering of ATR aluminia from niobium

    International Nuclear Information System (INIS)

    Shibuya, N.H.

    1987-01-01

    The characterization of resultante slag from Aluminothermic Reduction (ATR) process to obtain metallic niobium is presented. The slag was characterized for concentration and phases of aluminia by X-ray diffractometry. The results show that 70% of the slag is constituted by α aluminia. The lixiviation and calcination of the slag increased the α aluminia concentration to 95%, the slag was used for producing samples to be burning in three furnaces: electrical resistance furnace in the air, and two furnaces in the vacuum. The burned samples were characterized by microscopy, ultrasonic analysis, density measurements and X-ray diffractometry. The sintering in the vacuum is possible because the samples burned in vacuum presented major density. The formation of NbO 2 and mullite was observed, by X-ray diffractometry. The data from optical microscopy, density measurements and X-ray diffractometry show high porosity. (M.C.K.) [pt

  2. Influence of point defects on dosimetric properties and sintering capability of aluminia α

    International Nuclear Information System (INIS)

    Papin, Eric

    1997-01-01

    This work was devoted to the study of the influence of synthesis conditions on the thermoluminescence of aluminia α for use in ionizing radiation dosimetry. Powders are synthesized by heat treatment of pure aluminia γ or doped by impregnation technique. The studied parameters are the thermal cycle, the gas atmosphere of the furnace and the nature of the dopants (Mg 2+ , Cr 3+ , Th 4+ , Fe 3+ /Fe 2+ ). The thermoluminescence (TL) is connected with the presence of point defects. This technique consists in measuring the intensity of light emitted by a previously irradiated solid. Three TL peaks were observed. A peak around - 40 deg. C allows making evident the magnesium impurities and the oxygen vacations. The evolution of the intensity of the two peaks at 190 deg. C and 360 deg. C, is studied as a function of the oxygen partial pressure of the heat treatment and of the Mg 2+ , Cr 3+ and Th 4+ dopant concentrations. These investigations have permitted identifying the defects implied in the luminescence process of these two peaks, i.e. the aluminium vacations and the Cr 3+ ions substituted to Al 3+ . Thus aluminia powders having a high sensitivity to ionizing radiations (X rays, UV and γ radiations) have been synthesized. Utilization in dosimetry of the peaks at 190 deg. C and 360 deg. C is suggested. The reactivity of non-doped powders containing different types of point defects was analyzed by dilatometry. Thus, the influence of the atmosphere of powder preparation upon the sintering behaviour was made evident. The differences between the removal velocities are correlated with the variations in the aluminium vacancy concentrations. These results suppose that the limiting stage in sintering these powders is the Al 3+ ion diffusion

  3. Influence of point defects on dosimetric properties and sintering capability of aluminia {alpha}; Influence des defauts ponctuels sur les proprietes dosimetriques et sur l'aptitude au frittage de l'alumine {alpha}

    Energy Technology Data Exchange (ETDEWEB)

    Papin, Eric [Ecole Nationale Superieure des Mines, 42 - Saint-Etienne (France)

    1997-12-11

    This work was devoted to the study of the influence of synthesis conditions on the thermoluminescence of aluminia {alpha} for use in ionizing radiation dosimetry. Powders are synthesized by heat treatment of pure aluminia {gamma} or doped by impregnation technique. The studied parameters are the thermal cycle, the gas atmosphere of the furnace and the nature of the dopants (Mg{sup 2+}, Cr{sup 3+}, Th{sup 4+}, Fe{sup 3+}/Fe{sup 2+}). The thermoluminescence (TL) is connected with the presence of point defects. This technique consists in measuring the intensity of light emitted by a previously irradiated solid. Three TL peaks were observed. A peak around - 40 deg. C allows making evident the magnesium impurities and the oxygen vacations. The evolution of the intensity of the two peaks at 190 deg. C and 360 deg. C, is studied as a function of the oxygen partial pressure of the heat treatment and of the Mg{sup 2+}, Cr{sup 3+} and Th{sup 4+} dopant concentrations. These investigations have permitted identifying the defects implied in the luminescence process of these two peaks, i.e. the aluminium vacations and the Cr{sup 3+} ions substituted to Al{sup 3+}. Thus aluminia powders having a high sensitivity to ionizing radiations (X rays, UV and {gamma} radiations) have been synthesized. Utilization in dosimetry of the peaks at 190 deg. C and 360 deg. C is suggested. The reactivity of non-doped powders containing different types of point defects was analyzed by dilatometry. Thus, the influence of the atmosphere of powder preparation upon the sintering behaviour was made evident. The differences between the removal velocities are correlated with the variations in the aluminium vacancy concentrations. These results suppose that the limiting stage in sintering these powders is the Al{sup 3+} ion diffusion.

  4. Fabrication and properties of yttria, ceria doped zirconia-aluminia ceramic composites

    International Nuclear Information System (INIS)

    Lyubushkin, R.A.; Ivanov, O.N.; Chuev, V.P.; Buzov, A.A.

    2011-01-01

    At present, zirconia-based ceramics are gaining popularity in dentistry, particularly in fixed prosthodontics. clinically, it is important that ceramic restorations reproduce the translucency and color of natural teeth. Zirconia based ceramics is a high performance material with excellent biocompatibility and mechanical properties, which suggest its suitability for posterior fixed partial dentures. Y 2 O 3 -stabilized tetragonal zirconia polycrystalline (YTZ/Al 2 O 3 ) and CeO 2 -stabilized tetragonal zirconia polycrystalline (CZA) ceramics with high-performance were prepared for dental application by use the wet chemical route, consolidated by cold isostatic pressing, and two-step sintering method. Physical and mechanical properties test results show that the bending strength, fracture toughness, and the density of full sintered ceramics suggest that the material is relatively suitable for dental restoration.

  5. Study of plutonium sorption in aluminia column in the system HNO3-HF

    International Nuclear Information System (INIS)

    Araujo, J.A. de.

    1977-01-01

    The column chromatographic method using alumina has been applied successfully to study the sorption-desorption behavior of plutonium traces in HNO 3 -HF and HNO 3 -HF-UO 2 (NO 3 ) 2 systems, aiming to elaborate a process for recovering plutonium traces from reprocessing wastes, mainly in existing solutions where uranium is presented in macro quantities. Basically, the method consists in the sorption of plutonium by percolating a solution containing HNO 3 (0,1 to 0,8M) or uranyl nitrate (1-50 gU/l) and HF(0,1 to 0,3M) through an Al 2 O 3 collumn. The plutonium is fixed on Al 2 O 3 whereas the uranyl ions is collected in the efluent. The adsorption of Pu-III, Pu-IV and Pu-VI in the presence of HF was determined and Pu-IV can be almost completely sorbed. The Pu-IV is eluted by reduction to Pu-III in the column using 3 M HNO 3 -0,005M FeSO 4 at 50 0 C as elutrient. This method is very simple and can be applied for separation and purification of plutonium (traces) from uranyl nitrate or others coming solutions from wet chemistry of irradiated fuels [pt

  6. Synthesis by Sol-gel and characterization of catalysts Ag/Al{sub 2}O{sub 3}-CeO{sub 2}; Sintesis por Sol-gel y caracterizacion de catalizadores Ag/Al{sub 2}O{sub 3}-CeO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Zayas, M.L.; Perez H, R. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Rubio, E. [BUAP, Centro de Vinculacion, 72000 Puebla (Mexico); Velasco, A. [BUAP, Facultad de Quimica, 72000 Puebla (Mexico)

    2004-07-01

    Aluminia, cerium and mixed oxides Al{sub 2}O{sub 3}-CeO{sub 2} with different relationship Al/Ce (0.75, 0.50 and 0.25) were prepared by sol-gel and used as support for the Ag. The samples were characterized by XRD, DRIFT, TPR and adsorption of N{sub 2} to temperature of liquid nitrogen. The surface area BET showed that the materials that contain aluminia present near values among them. XRD allowed to identify to the cerianite in the oxides that whose support contains cerium and to the {alpha}-aluminia. A mixture of phases was observed in the aluminia. Vibration bands attributed to the bond Al-O and Ce-O were observed by DRIFT in the catalytic materials. TPR showed differences in the reducibility of the Ag precursor in the indicative catalysts of a different interaction with the support. (Author)

  7. Synthesis by Sol-gel and characterization of catalysts Ag/Al2O3-CeO2

    International Nuclear Information System (INIS)

    Zayas, M.L.; Perez H, R.; Rubio, E.; Velasco, A.

    2004-01-01

    Aluminia, cerium and mixed oxides Al 2 O 3 -CeO 2 with different relationship Al/Ce (0.75, 0.50 and 0.25) were prepared by sol-gel and used as support for the Ag. The samples were characterized by XRD, DRIFT, TPR and adsorption of N 2 to temperature of liquid nitrogen. The surface area BET showed that the materials that contain aluminia present near values among them. XRD allowed to identify to the cerianite in the oxides that whose support contains cerium and to the α-aluminia. A mixture of phases was observed in the aluminia. Vibration bands attributed to the bond Al-O and Ce-O were observed by DRIFT in the catalytic materials. TPR showed differences in the reducibility of the Ag precursor in the indicative catalysts of a different interaction with the support. (Author)

  8. Experimental results from a pilot plant for converting acid whey to potentially useful food products

    Energy Technology Data Exchange (ETDEWEB)

    Coughlin, R.W.; Marvin, C.; Julkowski, K.

    1978-01-01

    The pilot plant used a fluidized bed with lactase immobilized on aluminia as well as ultrafiltration and demineralization equipment. Conversion of lactose to its consitiuent monosaccharides was up to 84%, vs. 65% on a bench scale. Advantages of the fluidized bed reactor are its freedom from plugging, its lower pressure loss, and its adaptability to frequent cleaning, compared to a fixed bed.

  9. Fuel elements containing burnable poison

    International Nuclear Information System (INIS)

    Bamber, K.J.; Eaton, C.W.

    1989-01-01

    A burnable poison such as gadolinia is introduced into a nuclear fuel pin by way of thermal insulating pellets which serve to protect end caps from exposure to the intense heat generated by the fuel during irradiation. The pellets may comprise a sintered mixture of aluminia and gadolinia. (author)

  10. LIQUID PHASE SELECTIVE OXIDATION OF ETHYLBENZENE OVER ACTIVATED AL2O3 SUPPORTED V2O5 CATALYST

    Science.gov (United States)

    Acetophenone, a very useful industrial chemical for fragrance and flavoring agent and a solvent for plastics and resins, is usually produced as a byproduct of phenol production from cumeme. Aluminia supported vandium oxide catalyst is now explored for the selective oxidation of e...

  11. Market analysis of shale oil co-products. Appendices

    Energy Technology Data Exchange (ETDEWEB)

    1980-12-01

    Data are presented in these appendices on the marketing and economic potential for soda ash, aluminia, and nahcolite as by-products of shale oil production. Appendices 1 and 2 contain data on the estimated capital and operating cost of an oil shales/mineral co-products recovery facility. Appendix 3 contains the marketing research data.

  12. Luminescent Eu3+-doped transparent alumina ceramics with high hardness

    Czech Academy of Sciences Publication Activity Database

    Drdlíková, K.; Klement, R.; Hadraba, Hynek; Drdlík, D.; Galusek, D.; Maca, K.

    2017-01-01

    Roč. 37, č. 14 (2017), s. 4271-4277 ISSN 0955-2219 R&D Projects: GA MŠk(CZ) LQ1601; GA ČR(CZ) GA15-06390S Institutional support: RVO:68081723 Keywords : Aluminia * Europium * Photoluminescence (PL) spectra * Submicrocrystalline powders Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass OBOR OECD: Ceramics Impact factor: 3.411, year: 2016

  13. Inclusion of radioactive ion-exchange resins into inorganic binders

    International Nuclear Information System (INIS)

    Epimakhov, V.N.; Olejnik, M.S.

    2005-01-01

    The paper is devoted to inclusion of the radioactive ion-exchange resins into the portland, slag-portland and alumina cements. The degree of filling the solidified products achieves 7-10, 12 and 18.9-19.7% correspondingly under conservation of sufficient strength (not less 5 MPa). The coefficient of waste volume increasing during solidification does not exceed 1.5 under consideration of addition of 10 mass % of clay into aluminia cement [ru

  14. Heterogeneous phase gamma irradiation of ethylene-hydrogen mixtures

    International Nuclear Information System (INIS)

    Molinari, M.A.; Lires, O.A.; Videla, G.J.

    1975-11-01

    Experiments of radioinduced ethylene hydrogenation were performed. The G yield of volatile saturated hydrocarbons was 0,49 for silica-gel with simultaneous irradiation and 0,09-0,05 for the other solids (silica-alumina and molecular sieve 5A). The highest yield corresponds to 4,5% of saturated products in relation to initial ammount of ethylene (silica-gel). Polymerization was the most important reaction, with yields as high as 95%. Changes in color and appearance of silica-aluminia in contact with moisture was observed, after the irradiation process. (author) [es

  15. The 1989 progress report: Fine chemistry

    International Nuclear Information System (INIS)

    Laszlo, P.

    1989-01-01

    The 1989 progress report of the laboratory of Fine Chemistry of the Polytechnic School (France) is presented. The investigations are focused on the following subjects: nuclear magnetic resonance study of adsorbates, origin of claid inflating phenomena, models on water-claid thin films interaction, re-orientation of benzene adsorbed on aluminia, oxydation of cyclohexene, kaolinites, obtention of acrylates, recognition of molecules, biological chloration, distribution of addition products of N-benzylidene aniline and end ethers, epistemological reflection about representations in chemistry. The published papers, the conferences and Laboratory staff are listed [fr

  16. Preparation of Pd/γ- Al2O3 catalyst utilized in chemisorption of hydrogen isotopes

    International Nuclear Information System (INIS)

    David, Elena; Stefanescu, Doina; Stanciu, V.

    1997-01-01

    Separation and hydrogen isotope determination require packings with special properties, utilizable in separation columns. Consequently, such packings as catalysts using γ-aluminia and metallic palladium active component as holder were obtained. The γ-aluminia used as holder has been prepared starting from λ salts, easy soluble in water, such as Al 2 (NO 3 ) 3 ·9H 2 O, at a preset (6.2-6.4) controlled pH. At a first stage the Al(OH) 3 results which by calcination at controlled temperature transforms in γ-Al 2O3 . On this holder, in which the specific surface and porosity has been determined, metallic palladium has been deposed, using for impregnation a 2% PdCl 2 solution. The content of deposed palladium was determined as the difference between the content in the initial solution and solution remaining after holder impregnation. This content has been determined by atomic absorption and is within 0.5 - 1.2% Pd. After impregnation the catalyst has been dried, then granulated at the 0.16 mm size and activated by hydrogen at a flow rate of 300 vol H 2 /volume

  17. Analysis of Permalloy films prepared on anodized alumina templates

    Energy Technology Data Exchange (ETDEWEB)

    Getlawi, Saleh; Koblischka, Michael R.; Hartmann, Uwe [Institute of Experimental Physics, Saarland University, Saarbruecken (Germany)

    2010-07-01

    The magnetic properties of Permalloy (Py) systems have been extensively studied for thick films due to the important role in many technological applications, e.g., in magnetoresistive-based sensors and devices. Nanopatterned magnetic media are important for various current approaches in magnetoelectronics and magnetic recording. Commercially available anodized aluminia templates with pore diameters of 100 mm and 30 mm were employed as substrates for Py thin films. The films were prepared by dc-magnetron sputtering. The film thickness was between 7 nm and 30 nm. The obtained antidot patterns were observed by electron and force microscopy. The resulting magnetic domain structures were characterized by means of magnetic force microscopy performed in externally applied magnetic fields. Additionally, the magnetic parameters were characterized by means of SQUID magnetometry.

  18. Synthesis of α-Alumina (Corundum) and its Application

    International Nuclear Information System (INIS)

    Nay Thwe Kyi; Kyaw Myo Naing; Tin Tin Aye; Nyunt Wynn

    2005-09-01

    This paper described the preparation of aluminium isopropoxide from aluminium sheet at different heating times.Aluminium sheet is found to have a reaction with absolute isopropyl alcohol and mercury (II) chloride as a catalyst under nitrogen atmosphere. Aluminium isopropoxide was characterized by NMR, XRD and IR. Aluminium isopropoxide serves as a molecular precursor to derive pure alumina gel by hydrolysis under both homogeneous and heterogeneous conditions. Pyrolysis to this alumina gel transforms it into -aluminia (corundum) at 1200'C. The phase transformation during pyrolysis was characterized by XRD, SEM and TEM. The alumina (corundum) has porous crystalline nature with high surface aera, which may be used as efficient adsorbent packing material in coloumn chromatography for the seperation of vitamin A from the leaves. -alumina can be also used in catalysis

  19. Minerals yearbook: The mineral industry of Brazil. 1988 international review

    International Nuclear Information System (INIS)

    Ensminger, H.R.

    1988-01-01

    Brazil's gross domestic product (GDP) grew only slightly in 1988 to $277 billion at current prices. The growth rate was the smallest registered since 1983, when the rate was minus 2.8%. The economy's performance was strongly influenced by a 2% to 3% decrease in industrial production and civil construction. The mineral industry, however, countered the downward trend in the industrial sector and grew a modest 1.4%. Topics discussed in the report include the following: Government policies and programs; Production; Trade; Commodity review--Metals (Aluminum, Aluminia, and Bauxite, Columbium, Copper, Gold, Iron and Steel, Manganese, Tin, Titanium); Industrial Minerals (Gem stones, Phosphate rock, Quartz); Mineral fuels (Coal, Natural gas, Petroleum, Nuclear power); Nonmineral energy sources (Alcohol, Hydroelectric)

  20. Synthesis of no-carrier-added [{sup 18}F]fluoroacetate

    Energy Technology Data Exchange (ETDEWEB)

    Jaemin Jeong; Dongsoo Lee; Junekey Chung; Myungchul Lee; Changsoon Koh [Seoul National Univ. Hospital, Nuclear Medicine Dept., Seoul (Korea, Republic of); Samsik Kang [Seoul National Univ. Hospital, Natural Products Research Inst., Seoul (Korea, Republic of)

    1997-05-01

    To synthesize no-carrier-added potassium [{sup 18}F]fluoroacetate, Omesyl glycolate ethyl ester and O-tosyl glycolate ethyl ester were synthesized as prescursors. These precursors were radiolabeled by reacting with dried tetrabutylammonium [{sup 18}F]fluoride in the presence of tetrabutylammonium bicarbonate. O-Mesyl glycolate ethyl ester showed higher {sup 18}F incorporation (77.6% at 100{sup o}C) than O-tosyl glycolate ethyl ester (63.2% at 100{sup o}C). Resulting [{sup 18}F]fluoroacetate ethyl ester was hydrolyzed quantitatively by heating in 1 M potassium hydroxide solution. The [{sup 18}F]fluoroacetate was adsorbed to strong anion exchange resin and washed with excess water. Following elution with 1 M sodium bicarbonate solution and passing through Sep-Pak neutral aluminia column, the [{sup 18}F]fluoroacetate was obtained with 24.5% recovery (non-decay-corrected). Total labelling time from drying {sup 18}F to final product was 70 to 90 min. (author).

  1. [The study of the colorimetric characteristics of the cobalt-chrome alloys abutments covered by four different all-ceramic crowns by using dental spectrophotometer].

    Science.gov (United States)

    Chen, Yifan; Liu, Hongchun; Meng, Yukun; Chao, Yonglie; Liu, Changhong

    2015-06-01

    This study aims to evaluate the optical data of the different sites of the cobalt-chrome (Co-Cr) alloy abutments covered by four different all-ceramic crowns and the color difference between the crowns and target tab using a digital dental spectrophotometer. Ten Co-Cr alloy abutments were made and tried in four different groups of all-ceramic crowns, namely, Procera aluminia, Procera zirconia, Lava zirconia (Lava-Zir), and IPS E.max glass-ceramic lithium disilicate-reinforced monolithic. The color data of the cervical, body, and incisal sites of the samples were recorded and analyzed by dental spectrophotometer. The CIE L*, a*, b* values were again measured after veneering. The color difference between the abutments covered by all-ceramic crowns and A2 dentine shade tab was evaluated. The L* and b* values of the abutments can be increased by all of the four groups of all-ceramic copings, but a* values were decreased in most groups. A statistical difference was observed among four groups. After being veneered, the L* values of all the copings declined slightly, and the values of a*, b* increased significantly. When compared with A2 dentine shade tab, the ΔE of the crowns was below 4. Four ceramic copings were demonstrated to promote the lightness and hue of the alloy abutments effecttively. Though the colorimetric baseline of these copings was uneven, veneer porcelain can efficiently decrease the color difference between the samples and thee target.

  2. A medium resolution double crystal based small-angle neutron scattering instrument at Trombay

    International Nuclear Information System (INIS)

    Mazumder, S.; Sen, D.; Saravanan, T.; Vijayaraghavan, P.R.

    2001-01-01

    A double crystal-based moderate resolution small-angle neutron scattering instrument has been built and commissioned at the guide laboratory of Dhruva reactor, Bhabha Atomic Research Centre, Trombay, India. The instrument consists of a non-dispersive (1,-1) setting of 111 reflections of silicon single crystals with the sample between the two crystals. The neutron wavelength used is 0.312 nm. At 65 MW of reactor power, the peak count rate of the blank rocking curve is about 55 counts per second at the detector position and the ratio of integrated signal to integrated noise is ∼450 for a typical experiment with sintered aluminia. The accessible range of wave vector transfer q is found to be 0.003-0.173 nm -1 , which corresponds to a range of resolvable real-space dimension of 2000-40 nm, for these specimens. The instrument is calibrated with respect to the high resolution ultra small-angle neutron scattering instrument S18 at the Institute Laue-Langevin in Grenoble, France. (author)