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Sample records for zrw2o8 powders synthesized

  1. The Study on Thermal Expansion of Ceramic Composites with Addition of ZrW[2]O]8

    OpenAIRE

    Dedova, Elena Sergeevna; Shadrin, V. S.; Petrushina, M. Y.; Kulkov, Sergey Nikolaevich

    2016-01-01

    The studies on structure, phase composition and thermal properties of (Al[2]O[3] - 20 wt% ZrO[2]) - ZrW[2]O[8] ceramic composites obtained using nanosized, initial powders were conducted. Homogeneously distributed white particles on the polished surface of composites were observed. Phase composition of the composites was represented with corundum, monoclinic ZrO[2] and two modifications of ZrW[2]O[8] (tetragonal and cubic). Linear thermal expansion coefficient values of the composites were de...

  2. Study of Ti4+ substitution in ZrW2O8 negative thermal expansion materials

    International Nuclear Information System (INIS)

    Buysser, Klaartje de; Driessche, Isabel van; Putte, Bart van de; Schaubroeck, Joseph; Hoste, Serge

    2007-01-01

    Powder XRD-analysis and thermo-mechanical analysis on sintered TiO 2 -WO 3 -ZrO 2 mixtures revealed the formation of Zr 1-x Ti x W 2 O 8 solid solutions. A noticeable decrease in unit cell parameter 'a' and in the order-disorder transition temperature could be seen in the case of Zr 1-x Ti x W 2 O 8 solid solutions. Studies performed on other ZrW 2 O 8 solid solutions have attributed an increase in phase transition temperature to a decrease in free lattice volume, whereas a decrease in phase transition temperature was suggested to be due to the presence of a more disordered state. Our studies indicate that the phase transition temperature in our materials is strongly influenced by the bond dissociation energy of the substituting ion-oxygen bond. A decrease in bond strength may compensate for the effect of a decrease in lattice free volume, lowering the phase transition temperature as the degree of substitution by Ti 4+ increases. This hypothesis is proved by differential scanning calorimetry. - Graphical abstract: This study indicates that the phase transition temperature in our materials Zr 1-x Ti x W 2 O 8 is strongly influenced by the bond dissociation energy of the substituting ion-oxygen bond. A decrease in bond strength may compensate for the effect of a decrease in lattice-free volume, lowering the phase transition temperature

  3. High-temperature reactivity in the ZrW2O8-Cu system

    International Nuclear Information System (INIS)

    Verdon, C.; Dunand, D.C.

    1997-01-01

    Zirconium tungstate (ZrW 2 O 8 ) exhibits the unusual property of a negative coefficient of thermal expansion (CTE) over a wide range of temperature, from 0.3 to 1,050 K. As a reinforcement in a composite, zirconium tungstate can reduce the overall thermal expansion of the composite much more effectively than a ceramic with positive CTE. If a metallic matrix is used, the resulting composite will also exhibit high thermal conductivity, with applications such as heat sink for microelectronics devices (CTE matching that of silicon or alumina) or high precision optical elements subjected to thermal fluctuation (zero CTE). As a matrix, copper is prime candidate, because it has the second highest thermal conductivity of all metals after silver, and because it can be easily processed within the temperature window imposed by the metastability of ZrW 2 O 8 . Moreover, copper is already widely used in electronics industry and can be easily soldered. In the present work, the authors investigate the stability of ZrW 2 O 8 when hot-isostatically pressed with copper, in order to explore the processing feasibility of a low thermal expansion, high conductivity ZrW 2 O 8 -Cu composite

  4. Pressure-induced phase transformation in ZrW2O8 - Compressibility and thermal expansion of the orthorhombic phase

    International Nuclear Information System (INIS)

    Hu, Z.; Jorgensen, J.D.; Teslic, S.; Short, S.; Argyriou, D.N.

    1997-01-01

    In situ neutron powder diffraction has been used to show that the application of hydrostatic pressure at room temperature produces a transformation of ZrW 2 O 8 from the cubic to an orthorhombic phase beginning at 2.1 kbar and completed by 3.1 kbar, with a 5% reduction in volume. After release of pressure, the orthorhombic phase is retained at room temperature. Its thermal expansion is negative below room temperature, but is positive above room temperature with a transformation back to the cubic phase at about 390 K. The WO 4 groups are found to play the dominant role in both phase transformations. The volume compressibilities of the cubic and orthorhombic phases are 1.38 x 10 -3 and 1.53 x 10 -3 kbar -1 , respectively. (orig.)

  5. Assessing exchange-correlation functionals for elasticity and thermodynamics of α -ZrW2O8 : A density functional perturbation theory study

    Science.gov (United States)

    Weck, Philippe F.; Kim, Eunja; Greathouse, Jeffery A.; Gordon, Margaret E.; Bryan, Charles R.

    2018-04-01

    Elastic and thermodynamic properties of negative thermal expansion (NTE) α -ZrW2O8 have been calculated using PBEsol and PBE exchange-correlation functionals within the framework of density functional perturbation theory (DFPT). Measured elastic constants are reproduced within ∼ 2 % with PBEsol and ∼ 6 % with PBE. The thermal evolution of the Grüneisen parameter computed within the quasi-harmonic approximation exhibits negative values below the Debye temperature, consistent with observation. The standard molar heat capacity is predicted to be CP0 = 192.2 and 193.8 J mol-1K-1 with PBEsol and PBE, respectively. These results suggest superior accuracy of DFPT/PBEsol for studying the lattice dynamics, elasticity and thermodynamics of NTE materials.

  6. Syntheses and characterizations of LiFePO4 powders

    OpenAIRE

    Jugović, Dragana; Kuzmanović, Maja; Mitrić, Miodrag; Cvjetićanin, Nikola; Uskoković, Dragan

    2011-01-01

    The olivine type compositions LiMPO4 (M = Fe, Mn, Co) are among the most attractive materials for the positive electrode of lithium-ion battery. The benefits of using LiFePO4 are excellent cycle life, high structural stability, low cost and environmental friendliness. Here will be presented our efforts to obtain LiFePO4 powders through several synthesis methods. The differences in phase purity, microstructure, morphology, and electrochemical performances of synthesized powders were investigat...

  7. Preparation and Characterization of Nano-structured Ceramic Powders Synthesized by Emulsion Combustion Method

    International Nuclear Information System (INIS)

    Takatori, Kazumasa; Tani, Takao; Watanabe, Naoyoshi; Kamiya, Nobuo

    1999-01-01

    The emulsion combustion method (ECM), a novel powder production process, was originally developed to synthesize nano-structured metal-oxide powders. Metal ions in the aqueous droplets were rapidly oxidized by the combustion of the surrounding flammable liquid. The ECM achieved a small reaction field and a short reaction period to fabricate the submicron-sized hollow ceramic particles with extremely thin wall and chemically homogeneous ceramic powder. Alumina, zirconia, zirconia-ceria solid solutions and barium titanate were synthesized by the ECM process. Alumina and zirconia powders were characterized to be metastable in crystalline phase and hollow structure. The wall thickness of alumina was about 10 nm. The zirconia-ceria powders were found to be single-phase solid solutions for a wide composition range. These powders were characterized as equiaxed-shape, submicron-sized chemically homogeneous materials. The powder formation mechanism was investigated through the synthesis of barium titanate powder with different metal sources

  8. Characterization of combustion synthesized zirconia powder by UV

    Indian Academy of Sciences (India)

    . The surface acidbase properties of these samples were also investigated by indicator titration method. The catalytic activity was probed with transfer hydrogenation reaction in liquid phase. It was found that combustion synthesized zirconia did ...

  9. STABILIZATION OF TEMPERATURE REGIMES WHILE SYNTHESIZING DIAMOND POWDERS

    Directory of Open Access Journals (Sweden)

    A. I. Dudiak

    2012-01-01

    Full Text Available The paper considers peculiar features of artificial diamond powder synthesis process and also direct and indirect methods for temperature measurement in a reaction cell of high-pressure apparatus. Differences in temperature regimes of diamond synthesis associated with time fixation of strain and heating power have been analyzed in the paper. The paper  reveals their impracticability.Theoretical methodology for temperature correction in the reaction cell has been proposed in the paper. An algorithm controlling cell material heating has been developed on the basis of a microcontroller and it makes it possible to stabilize temperature in the reaction mixture that permits to improve quality and strength characteristics of the obtained diamond powders. The paper contains a graphic interpretation of calculation results with the help of the proposed algorithm. 

  10. Photoluminescence of sol–gel synthesized PZT powders

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez-Aranda, M.C. [Coordinación para la Innovación y Aplicación de la Ciencia y la Tecnología-Universidad Autónoma de San Luis Potosí, Av. Sierra Leona No.550,Col. Lomas 2a. sección, C.P. 78210 San Luis Potosí, SLP, México (Mexico); Calderón-Piñar, F. [Centro de Investigación y de Estudios Avanzados del I.P.N. Unidad Querétaro, Libramiento Norponiente No. 2000, Fracc. Real de Juriquilla, C.P. 7623 Querétaro, Qro, México (Mexico); Facultad de Física/IMRE, San Lázaro y L, Universidad de la Habana, C.P. 10400 Habana (Cuba); Hernández-Landaverde, M.A. [Centro de Investigación y de Estudios Avanzados del I.P.N. Unidad Querétaro, Libramiento Norponiente No. 2000, Fracc. Real de Juriquilla, C.P. 7623 Querétaro, Qro, México (Mexico); and others

    2016-11-15

    A wide band of photoluminescence (PL) emission in structurally disordered lead zirconate titanate (PZT) powders, prepared by sol–gel route, was observed at room temperature excited with a laser line (488 nm). Powders with PbZr{sub 0.53}Ti{sub 0.47}O{sub 3} nominal composition annealed at different temperatures were studied by X-ray diffraction, Raman spectroscopy, Luminescence, Diffuse Reflectance and Electronic Paramagnetic Resonance Spectroscopy (EPR). Our results indicate that the PL response can be associated to order–disorder degree in the perovskite structure, with the exception of samples annealed at low temperature, where a mixture of oxides precursorsГ—Ві phases was observed. Furthermore, in quasi-crystalline ordered samples (95% of crystallinity) a small generation of PL remains. In these experiments, the band gap increases with the formation of crystalline structure. EPR experiments were conducted in order to follow the evolution of paramagnetic species with thermal treatment from the mixture of oxides precursors to the perovskite phase and paramagnetic point defects were identified (Pb{sup +3} and Ti{sup +3}). EPR data suggest the presence of order–disorder within the lattice network. Paramagnetic species are similar in samples treated at 700 and 800 °C, nevertheless the emission intensity decreases by a factor of 6, indicating that the defects associated with PL are not paramagnetic at both temperatures.

  11. Granulometric analysis of metallic oxide in ceramic powder form synthesized by different methods

    International Nuclear Information System (INIS)

    Neiva, L.S.; Simoes, A.N.; Simoes, V.N.; Bispo, A.; Gama, L.

    2012-01-01

    The aim of this work is to synthesize ceramic powders based on CuO/CeO 2 by means two different synthesis methods, they are: the combustion reaction method and Pechini method. It's part of the aim of this work subject all samples to a synthesized qualitative and quantitative chemical analysis, using the technique EDX and then to a granulometric analysis. The samples of the ceramic powder based on CuO/CeO 2 synthesized in this work by means of the two above synthesis methods, contain various concentrations of CuO ranging between 0 and 0.5 mol. According to the results, only the Pechini method of synthesis exerted a significant and defined influence on the capacity of particle unit agglomeration in these powders (author)

  12. Zirconium tungstate/epoxy nanocomposites: effect of nanoparticle morphology and negative thermal expansivity.

    Science.gov (United States)

    Wu, Hongchao; Rogalski, Mark; Kessler, Michael R

    2013-10-09

    The ability to tailor the coefficient of thermal expansion (CTE) of a polymer is essential for mitigating thermal residual stress and reducing microcracks caused by CTE mismatch of different components in electronic applications. This work studies the effect of morphology and thermal expansivity of zirconium tungstate nanoparticles on the rheological, thermo-mechanical, dynamic-mechanical, and dielectric properties of ZrW2O8/epoxy nanocomposites. Three types of ZrW2O8 nanoparticles were synthesized under different hydrothermal conditions and their distinct properties were characterized, including morphology, particle size, aspect ratio, surface area, and CTE. Nanoparticles with a smaller particle size and larger surface area led to a more significant reduction in gel-time and glass transition temperature of the epoxy nanocomposites, while a higher initial viscosity and significant shear thinning behavior was found in prepolymer suspensions containing ZrW2O8 with larger particle sizes and aspect ratios. The thermo- and dynamic-mechanical properties of epoxy-based nanocomposites improved with increasing loadings of the three types of ZrW2O8 nanoparticles. In addition, the introduced ZrW2O8 nanoparticles did not negatively affect the dielectric constant or the breakdown strength of the epoxy resin, suggesting potential applications of ZrW2O8/epoxy nanocomposites in the microelectronic insulation industry.

  13. Combined wet-chemical process to synthesize 65PMN-35PT nanosized powders

    International Nuclear Information System (INIS)

    Santos, Luis P.S.; Longo, Elson; Leite, Edson R.; Camargo, Emerson R.

    2004-01-01

    Columbite MgNb 2 O 6 precursors were synthesized by a wet-chemical method by means of the dissolution of Nb 2 O 5 .5H 2 O and magnesium carbonate in a solution of oxalic acid. Pure 65PMN-35PT powders could be obtained by the columbite method with the use of the partial oxalate and oxidant peroxo methods. Powders were characterized by X-ray diffraction and FT-Raman spectroscopy showing that pure 65PMN-35PT are obtained when the powders are calcined up to 800 deg. C, without any trace of Pb-Nb pyrochlore. Cubic Pb 1,86 Mg 0.24 Nb 1.76 O 6.5 pyrochlore phase is formed by lead loss in the powders calcined at 900 deg. C and higher temperatures as undoubtedly characterized by Raman spectroscopy

  14. Thermal Plasma Spheroidization of High-Nitrogen Stainless Steel Powder Alloys Synthesized by Mechanical Alloying

    Science.gov (United States)

    Razumov, Nikolay G.; Popovich, Anatoly A.; Wang, QingSheng

    2018-03-01

    This paper presents the results of experimental studies on the treatment of Fe-23Cr-11Mn-1N high-nitrogen stainless steel powder alloys, synthesized by the mechanical alloying (MA) of elemental powders in the flow of a thermal plasma. Fe-23Cr-11Mn-1N high-nitrogen stainless steel powder alloys were prepared by MA in the attritor under an argon atmosphere. For spheroidization of Fe-23Cr-11Mn-1N high-nitrogen stainless steel powder alloys, the TekSphero 15 plant manufactured by Tekna Plasma Systems Inc was used. The studies have shown the possibility of obtaining Fe-23Cr-11Mn-1N high-nitrogen spherical powders steel alloys from the powder obtained by MA. According to the results of a series of experiments, it was found that the results of plasma spheroidization of powders essentially depend on the size of the fraction due to some difference in the particle shape and flowability, and on the gas regime of the plasma torch. It is established that during the plasma spheroidization process, some of the nitrogen leaves the alloy. The loss rate of nitrogen depends on the size of the initial particles.

  15. Characterization of Ce0.9Gd0.1O1.95 powders synthesized by spray drying

    DEFF Research Database (Denmark)

    Blennow Tullmar, Peter; Chen, Weiwu; Lundberg, Mats

    2009-01-01

    Ce0.9Gd0.1O1.95 powders were synthesized by spray drying and successive calcinations. The phase purity, BET surface area, and particle morphology of as-sprayed and calcined powders were characterized. After calcination above 300 °C, the powders were single phase and showed a BET surface area of 68...

  16. Nanosize stabilization of cubic and tetragonal phases in reactive plasma synthesized zirconia powders

    Energy Technology Data Exchange (ETDEWEB)

    Jayakumar, S., E-mail: sjayakumar.physics@gmail.com [Research and Development Centre, Bharathiar University, Coimbatore 641 014 (India); Department of Physics, Pollachi Institute of Engineering and Technology, Pollachi 642 205 (India); Ananthapadmanabhan, P.V.; Thiyagarajan, T.K. [Laser and Plasma Technology Division, BARC, Trombay, Mumbai 400 085 (India); Perumal, K. [Vision for Wisdom, Temple of Consciousness, Aliyar 642 101 (India); Mishra, S.C. [Department of Metallurgical and Materials Engg, National Institute of Technology, Rourkela 769 008 (India); Suresh, G. [Department of Physics, Park College of Engineering and Technology, Coimbatore 641 659 (India); Su, L.T.; Tok, A.I.Y. [School of Materials Science and Engg, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639 798 (Singapore)

    2013-06-15

    Pure zirconium oxide powders with particle size 2–33 nm are synthesized by reactive plasma processing. Transmission electron microscopy investigation of these particles revealed size dependent behavior for their phase stabilization. The monoclinic phase is found to be stable when particle size is ≥20 nm; Tetragonal is found to be stabilized in the range of 7–20 nm and as the particle size decreases to 6 nm and less, the cubic phase is stabilized. - Highlights: ► Direct conversion of micron-sized zirconium hydride powder to single crystal ZrO{sub 2} nanopowder. ► Size dependent stabilization of cubic, tetragonal and monoclinic phases in the reactive plasma synthesized ZrO{sub 2} nanopowder. ► Transmission electron microscopic investigation to identify particles of different sizes and their corresponding phase structure.

  17. Solid-state reactions to synthesize nanostructured lead selenide semiconductor powders by high-energy milling

    Energy Technology Data Exchange (ETDEWEB)

    Rojas-Chavez, H., E-mail: uu_gg_oo@yahoo.com.mx [Centro de Investigacion e Innovacion Tecnologica - IPN, Cerrada de CECATI s/n, Col. Santa Catarina, Del. Azcapotzalco (Mexico) and Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada - IPN, Legaria 694, Col. Irrigacion, Del. Miguel Hidalgo (Mexico); Reyes-Carmona, F. [Facultad de Quimica - UNAM, Circuito de la Investigacion Cientifica s/n, C.U. Del. Coyoacan (Mexico); Jaramillo-Vigueras, D. [Centro de Investigacion e Innovacion Tecnologica - IPN, Cerrada de CECATI s/n, Col. Santa Catarina, Del. Azcapotzalco (Mexico)

    2011-10-15

    Highlights: {yields} PbSe synthesized from PbO instead of Pb powder do not require an inert atmosphere. {yields} During high-energy milling oxygen has to be chemically reduced from the lead oxide. {yields} Solid-state and solid-gas chemical reactions promote both solid and gaseous products. -- Abstract: Both solid-solid and gas-solid reactions have been traced during high-energy milling of Se and PbO powders under vial (P, T) conditions in order to synthesize the PbSe phase. Chemical and thermodynamic arguments are postulated to discern the high-energy milling mechanism to transform PbO-Se micropowders onto PbSe-nanocrystals. A set of reactions were evaluated at around room temperature. Therefore an experimental campaign was designed to test the nature of reactions in the PbO-Se system during high-energy milling.

  18. Solid-state reactions to synthesize nanostructured lead selenide semiconductor powders by high-energy milling

    International Nuclear Information System (INIS)

    Rojas-Chavez, H.; Reyes-Carmona, F.; Jaramillo-Vigueras, D.

    2011-01-01

    Highlights: → PbSe synthesized from PbO instead of Pb powder do not require an inert atmosphere. → During high-energy milling oxygen has to be chemically reduced from the lead oxide. → Solid-state and solid-gas chemical reactions promote both solid and gaseous products. -- Abstract: Both solid-solid and gas-solid reactions have been traced during high-energy milling of Se and PbO powders under vial (P, T) conditions in order to synthesize the PbSe phase. Chemical and thermodynamic arguments are postulated to discern the high-energy milling mechanism to transform PbO-Se micropowders onto PbSe-nanocrystals. A set of reactions were evaluated at around room temperature. Therefore an experimental campaign was designed to test the nature of reactions in the PbO-Se system during high-energy milling.

  19. The effect of hydrothermal treatment on samaria and gadolinia doped ceria powders synthesized by coprecipitation

    International Nuclear Information System (INIS)

    Arakaki, Alexander Rodrigo; Yoshito, Walter Kenji; Ussui, Valter; Lazar, Dolores Ribeiro Ricci

    2009-01-01

    One of the main applications of ceria-based (CeO 2 ) ceramics is the manufacturing of Intermediate Temperature Solid Oxide Fuel Cells electrolytes. In order to improve ionic conductivity and densification of these materials various powder synthesis routes have been studied. In this work powders with composition Ce 0.8 (SmGd) 0.2 O 1.9h ave been synthesized by coprecipitation and hydrothermal treatment. A concentrate of rare earths containing 90wt% of CeO 2 and other containing 51% of Sm 2 O 3 and 30% of Gd 2 O 3 , both prepared from monazite processing, were used as precursor materials. The powders were characterized by X-ray diffraction, scanning and transmission electron microscopy, agglomerate size distribution by laser scattering and specific surface area by gas adsorption. Ceramic sinterability was evaluated by dilatometry and density measurements by Archimedes method. High specific surface area powders (~100m 2 /g) and cubic fluorite structure were obtained after hydrothermal treatment around 200 deg C. Ceramic densification was improved when compared to the one prepared from powders calcined at 800 deg C. (author)

  20. Characterization of dense lead lanthanum titanate ceramics prepared from powders synthesized by the oxidant peroxo method

    Energy Technology Data Exchange (ETDEWEB)

    Pinto, Alexandre H. [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Departamento de Quimica, UFSCar-Universidade Federal de Sao Carlos, Rod.Washington Luis km 235, CP 676 Sao Carlos, SP 13565-905 (Brazil); Souza, Flavio L., E-mail: flavio.souza@ufabc.edu.br [Centro de Ciencias Naturais e Humanas, Universidade Federal do ABC, Rua Santa Adelia 166, Bangu, Santo Andre, SP 09210-170 (Brazil); Chiquito, Adenilson J., E-mail: chiquito@df.ufscar.br [Departamento de Fisica, UFSCar-Federal University of Sao Carlos, Rod.Washington Luis km 235, CP 676 Sao Carlos, SP 13565-905 (Brazil); Longo, Elson, E-mail: elson@iq.unesp.br [Instituto de Quimica de Araraquara, UNESP-Universidade Estadual Paulista, Rua Francisco Degni, CP 355 Araraquara, SP 14801-907 (Brazil); Leite, Edson R., E-mail: derl@power.ufscar.br [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Departamento de Quimica, UFSCar-Universidade Federal de Sao Carlos, Rod.Washington Luis km 235, CP 676 Sao Carlos, SP 13565-905 (Brazil); Camargo, Emerson R., E-mail: camargo@ufscar.br [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Departamento de Quimica, UFSCar-Universidade Federal de Sao Carlos, Rod.Washington Luis km 235, CP 676 Sao Carlos, SP 13565-905 (Brazil)

    2010-12-01

    Nanosized powders of lead lanthanum titanate (Pb{sub 1-x}La{sub x}TiO{sub 3}) were synthesized by means of the oxidant-peroxo method (OPM). Lanthanum was added from 5 to 30% in mol through the dissolution of lanthanum oxide in nitric acid, followed by the addition of lead nitrate to prepare a solution of lead and lanthanum nitrates, which was dripped into an aqueous solution of titanium peroxo complexes, forming a reactive amorphous precipitate that could be crystallized by heat treatment. Crystallized powders were characterized by FT-Raman spectroscopy and X-ray powder diffraction, showing that tetragonal perovskite structure is obtained for samples up to 25% of lanthanum and cubic perovskite for samples with 30% of lanthanum. Powders containing 25 and 30% in mol of lanthanum were calcined at 700 deg. C for 2 h, and in order to determine the relative dielectric permittivity and the phase transition behaviour from ferroelectric-to-paraelectric, ceramic pellets were prepared and sintered at 1100 or 1150 deg. C for 2 h and subjected to electrical characterization. It was possible to observe that sample containing 25% in mol of La presented a normal behaviour for the phase transition, whereas the sample containing 30% in mol of La presented a diffuse phase transition and relaxor behaviour.

  1. Characterization of dense lead lanthanum titanate ceramics prepared from powders synthesized by the oxidant peroxo method

    International Nuclear Information System (INIS)

    Pinto, Alexandre H.; Souza, Flavio L.; Chiquito, Adenilson J.; Longo, Elson; Leite, Edson R.; Camargo, Emerson R.

    2010-01-01

    Nanosized powders of lead lanthanum titanate (Pb 1-x La x TiO 3 ) were synthesized by means of the oxidant-peroxo method (OPM). Lanthanum was added from 5 to 30% in mol through the dissolution of lanthanum oxide in nitric acid, followed by the addition of lead nitrate to prepare a solution of lead and lanthanum nitrates, which was dripped into an aqueous solution of titanium peroxo complexes, forming a reactive amorphous precipitate that could be crystallized by heat treatment. Crystallized powders were characterized by FT-Raman spectroscopy and X-ray powder diffraction, showing that tetragonal perovskite structure is obtained for samples up to 25% of lanthanum and cubic perovskite for samples with 30% of lanthanum. Powders containing 25 and 30% in mol of lanthanum were calcined at 700 deg. C for 2 h, and in order to determine the relative dielectric permittivity and the phase transition behaviour from ferroelectric-to-paraelectric, ceramic pellets were prepared and sintered at 1100 or 1150 deg. C for 2 h and subjected to electrical characterization. It was possible to observe that sample containing 25% in mol of La presented a normal behaviour for the phase transition, whereas the sample containing 30% in mol of La presented a diffuse phase transition and relaxor behaviour.

  2. Zeolitic adsorbent synthesized from powdered waste porcelain, and its capacity for heavy metal removal

    International Nuclear Information System (INIS)

    Wajima, T.; Ikegami, Y.

    2006-01-01

    A zeolitic adsorbent was synthesized from powdered waste porcelain kept at 80 o C for 24 h. The product contained the zeolite phases Na-P1 and hydroxysodalite. The product with the highest cation exchange capacity (CEC) was synthesized using 4 M NaOH and the sample weight / volume of alkali solution ratio was 1/4. The highest CEC obtained for the product was almost 1900 mmol/kg, which is the same as that of natural zeolite. The product with the highest CEC was tested for its ability to remove heavy metals (Fe, Cu, Ni, Zn, Pb, Cd, Mn, Cr, Al, B,Mo) from an acidic solution (pH 2). The product can neutralize the acidic solution to almost pH 7, and the capacity of the product for the removal of heavy metals is higher than that of the natural zeolite, except for Mo and B. (authors)

  3. Structure and hardness of a hard metal alloy prepared with a WC powder synthesized at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Costa, F.A. da [Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais, UFRN, Campus Universitario, 59072-970 Natal, RN (Brazil)], E-mail: francineac@yahoo.com; Medeiros, F.F.P. de [Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais, UFRN, Campus Universitario, 59072-970 Natal, RN (Brazil); Silva, A.G.P. da [Laboratorio de Materiais Avancados, UENF, 28015-620 Campos de Goytacazes, RJ (Brazil); Gomes, U.U. [Departamento de Fisica Teorica e Experimental, UFRN, Campus Universitario, 59072-970 Natal, RN (Brazil); Filgueira, M. [Laboratorio de Materiais Avancados, UENF, 28015-620 Campos de Goytacazes, RJ (Brazil); Souza, C.P. de [Laboratorio de Termodinamica e Reatores, UFRN, Campus Universitario, 59072-970 Natal, RN (Brazil)

    2008-06-25

    The structure and hardness of a WC-10 wt% Co alloy prepared with an experimental WC powder are compared with those of another alloy of the same composition produced under the same conditions and prepared with a commercial WC powder. The experimental WC powder was synthesized by a gas-solid reaction between APT and methane at low temperature and the commercial WC powder was conventionally produced by a solid-solid reaction between tungsten and carbon black. WC-10 wt% Co alloys with the two powders were prepared under the same conditions of milling and sintering. The structure of the sample prepared with the experimental WC powder is homogeneous and coarse grained. The structure of the sample prepared with the commercial powder is heterogeneous. Furthermore the size and shape of the WC grains are significantly different.

  4. Superior sinterability of nano-crystalline gadolinium doped ceria powders synthesized by co-precipitation method

    International Nuclear Information System (INIS)

    Hari Prasad, D.; Kim, H.-R.; Park, J.-S.; Son, J.-W.; Kim, B.-K.; Lee, H.-W.; Lee, J.-H.

    2010-01-01

    Reduced sintering temperature of doped ceria can greatly simplify the fabrication process of solid oxide fuel cells (SOFCs) by utilizing the co-firing of all cell components with a single step. In the present study, nano-crystalline gadolinium doped ceria (GDC) powders of high sinterability at lower sintering temperature has been synthesized by co-precipitation at room temperature. The successful synthesis of nano-crystalline GDC was confirmed by XRD, TEM and Raman spectroscopy analysis. Dilatometry studies showed that GDC prepared by this method can be fully densified (97% relative density) at a sintering temperature of 950 o C which is fairly lower than ever before. It has also been found that the sintered samples have a higher ionic conductivity of 1.64 x 10 -2 S cm -1 at 600 o C which is suitable for the intermediate temperature SOFC application.

  5. Syntheses and crystal structure determination by X-ray powder diffraction of new compounds of Benzovesamicol

    International Nuclear Information System (INIS)

    Rukiah, M.; Assaad, Th.

    2012-06-01

    The compound 2,2,2-Trifluoro-N-(1a,2,7,7 a-tetra-hydronaphtho[2,3-b]oxiren-3-yl)- acetamide, C 1 2H 1 0F 3 NO 2 , an important precursor in the preparation of benzovesamicol analogues for the diagnosis of Alzheimers disease, was prepared by the epoxidation of 5,8-dihydronaphthalene-1-amine using 3-chloroperoxybenzoic acid. The structure was determined by X-ray powder diffraction, multinuclear NMR spectroscopy and FT-IR spectroscopy. A pair of molecules form intermolecular N- H...O hydrogen bonds, involving the amino and oxirene groups, to produce a dimer.The two racemic compounds (2RS,3RS)-5-amino-3-(4-phenylpiperazin-1-yl)-1,2,3,4 tetrahydronaphthalene-2-ol, C 2 0H 2 5N 3 O, (I) and (2RS,3RS)-5-amino-3-[4-(3- methoxyphenyl)piperazin-1-yl]-1,2,3,4-tetrahydronaphthalene-2-ol, C 2 1H 2 7N 3 O 2 , (II) important benzovesamicol analogues for the diagnosis of Alzheimer's disease, have been synthesized and characterized by FT-IR, and 1 H and 13 C NMR spectroscopic analyses. The crystal structures were analyses using powder diffraction as no suitable single crystal were obtained. The two compounds are racemic mixtures of enantiomers which crystallize in the monoclinic system in a centrosymmetric space group (P21/c). Crystallography, in particular powder X-ray diffraction, was pivotal in revealing that the enantio-resolution did not succeed. In two compounds, the piperazine ring has a chair conformation, while the cyclohexene ring assumes a half-chair conformation. In (I) the crystal packing is mediated by weak contacts, principally by complementary intermolecular N--H...O hydrogen bonds that connect successive molecules into a chain. Further stabilization is provided by weak C--H...N contacts and by a weak intermolecular C--H...π interaction. While in (II), the crystal packing is dominated by intermolecular O--H...N hydrogen bonding which links molecules along the c direction. (authors)

  6. Microstructure and Corrosion Behavior of Laser Synthesized Cobalt Based Powder on Ti-6Al-4V

    Science.gov (United States)

    Adesina, O. S.; Popoola, A. P. I.; Pityana, S. L.; Oloruntoba, D. T.

    2018-05-01

    The corrosion behavior of titanium alloys when used for various dynamic offshore components has been a major concern of titanium drilling risers in deepwater energy extraction. A way of achieving specified requirement is the development of coatings suitable to protect the base material against corrosion. In this work, laser cladding technique which is known as a leading edge due to its distinctive properties and outcomes was used in synthesizing Co-based powder on titanium alloy. The processing parameters used were laser power of 900W; scan speed of 0.6 to 1.2 m/min; powderfeedrate1.0g/min;beamspotsize3mm;gasflowrate1.2L/min.The effects of cobalt addition and laser parameters on corrosion behavior of laser clad Ti6AL4V coating in 0.5M sulfuric medium were investigated using linear potentiodynamic polarization. The changes in microstructure and corrosion behavior were analyzed using scanning electron microscopy (SEM) while the X –ray diffraction (XRD) indicates the intermetallics in the coatings. Results showed that the coatings displayed good metallurgical bonding with dendritic formations between the coatings and the substrate. The anodic current density increased with lower scan speed. However, the corrosion current densities of laser-clad samples were lower than Ti6Al4V alloy.

  7. Investigations on Bi25FeO40 powders synthesized by hydrothermal and combustion-like processes

    International Nuclear Information System (INIS)

    Köferstein, Roberto; Buttlar, Toni; Ebbinghaus, Stefan G.

    2014-01-01

    The syntheses of phase-pure and stoichiometric iron sillenite (Bi 25 FeO 40 ) powders by a hydrothermal (at ambient pressure) and a combustion-like process are described. Phase-pure samples were obtained in the hydrothermal reaction at 100 °C (1), whereas the combustion-like process leads to pure Bi 25 FeO 40 after calcination at 750 °C for 2 h (2a). The activation energy of the crystallite growth process of hydrothermally synthesized Bi 25 FeO 40 was calculated as 48(9) kJ mol −1 . The peritectic point was determined as 797(1) °C. The optical band gaps of the samples are between 2.70(7) eV and 2.81(6) eV. Temperature and field-depending magnetization measurements (5−300 K) show a paramagnetic behaviour with a Curie constant of 55.66×10 −6 m 3 K mol −1 for sample 1 and C=57.82×10 −6 m 3 K mol −1 for sample 2a resulting in magnetic moments of µ mag =5.95(8) µ B mol −1 and µ mag =6.07(4) µ B mol −1 . The influence of amorphous iron-oxide as a result of non-stoichiometric Bi/Fe ratios in hydrothermal syntheses on the magnetic behaviour was additionally investigated. - Graphical abstract: Bi 25 FeO 40 powders were prepared by a hydrothermal method and a combustion process. The optical band gaps and the peritectic point were determined. The magnetic behaviour was investigated depending on the synthesis and the initial Bi/Fe ratios. The influence of amorphous iron-oxide on the magnetic properties was examined. - Highlights: • Two simple syntheses routes for stoichiometric Bi 25 FeO 40 powders using starch as polymerization agent. • Monitoring the phase evolution and crystallite growth kinetics during the syntheses. • Determination of the optical band gap and melting point. • Investigations of the magnetic behaviour of Bi 25 FeO 40 powders. • Influence of amorphous iron oxide and a non-stoichiometric Bi/Fe ratio on the magnetic behaviour

  8. Investigations on Bi{sub 25}FeO{sub 40} powders synthesized by hydrothermal and combustion-like processes

    Energy Technology Data Exchange (ETDEWEB)

    Köferstein, Roberto, E-mail: roberto.koeferstein@chemie.uni-halle.de; Buttlar, Toni; Ebbinghaus, Stefan G.

    2014-09-15

    The syntheses of phase-pure and stoichiometric iron sillenite (Bi{sub 25}FeO{sub 40}) powders by a hydrothermal (at ambient pressure) and a combustion-like process are described. Phase-pure samples were obtained in the hydrothermal reaction at 100 °C (1), whereas the combustion-like process leads to pure Bi{sub 25}FeO{sub 40} after calcination at 750 °C for 2 h (2a). The activation energy of the crystallite growth process of hydrothermally synthesized Bi{sub 25}FeO{sub 40} was calculated as 48(9) kJ mol{sup −1}. The peritectic point was determined as 797(1) °C. The optical band gaps of the samples are between 2.70(7) eV and 2.81(6) eV. Temperature and field-depending magnetization measurements (5−300 K) show a paramagnetic behaviour with a Curie constant of 55.66×10{sup −6} m{sup 3} K mol{sup −1} for sample 1 and C=57.82×10{sup −6} m{sup 3} K mol{sup −1} for sample 2a resulting in magnetic moments of µ{sub mag}=5.95(8) µ{sub B} mol{sup −1} and µ{sub mag}=6.07(4) µ{sub B} mol{sup −1}. The influence of amorphous iron-oxide as a result of non-stoichiometric Bi/Fe ratios in hydrothermal syntheses on the magnetic behaviour was additionally investigated. - Graphical abstract: Bi{sub 25}FeO{sub 40} powders were prepared by a hydrothermal method and a combustion process. The optical band gaps and the peritectic point were determined. The magnetic behaviour was investigated depending on the synthesis and the initial Bi/Fe ratios. The influence of amorphous iron-oxide on the magnetic properties was examined. - Highlights: • Two simple syntheses routes for stoichiometric Bi{sub 25}FeO{sub 40} powders using starch as polymerization agent. • Monitoring the phase evolution and crystallite growth kinetics during the syntheses. • Determination of the optical band gap and melting point. • Investigations of the magnetic behaviour of Bi{sub 25}FeO{sub 40} powders. • Influence of amorphous iron oxide and a non-stoichiometric Bi/Fe ratio on the

  9. A potential route to synthesize imporous MgB{sub 2} bulks by pretreatment of B powder at ambient pressure

    Energy Technology Data Exchange (ETDEWEB)

    Pan, X F; Zhou, J D; Zhao, Y [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Cheng, C H [Superconductivity Research Group, School of Materials Science and Engineering, University of New South Wales, Sydney, 2052 NSW (Australia)], E-mail: yzhao@home.swjtu.edu.cn

    2009-04-15

    Imporous MgB{sub 2} bulks with a density of 1.82 g cm{sup -3} have been synthesized by pretreatment of B powder in an in situ solid-state reaction at ambient pressure. The results show that the MgB{sub 2} with B powder pretreatment has a significant improvement in J{sub c}, B{sub irr}, microstructure and intergranular coupling, but with no decrease of T{sub c}. At 20 K and 4 T, the J{sub c} is enhanced by 4 times by the pretreatment of the B powder. For the B pretreated MgB{sub 2}, the B{sub irr} at 20 K reaches 5 T and J{sub c} at 10 K and 6 T reaches 2200 A cm{sup -2}, compared to 4.2 T and 670 A cm{sup -2} for the B-not-pretreated MgB{sub 2}. It is argued that the small amounts of highly dispersed carbon in B powder may enhance the mobility of B particles during the reaction of B and Mg, which avoids the formation of voids in the positions of Mg particles.

  10. Size effect in barium titanate powders synthesized by different hydrothermal methods

    International Nuclear Information System (INIS)

    Sun Weian

    2006-01-01

    The size effect in barium titanate (BaTiO 3 ) was investigated both experimentally and theoretically. Tetragonal BaTiO 3 powders with average sizes from 80 to 420 nm were directly prepared by different hydrothermal methods. The tetragonality of the hydrothermal BaTiO 3 decreased with decreasing particle size, which exhibited a dependence on the synthesis method. A phenomenological model for the size effect was proposed to interpret the experimental observations. The influence of the defects, mainly the lattice hydroxyl, on the size effect was investigated to understand the correlation between the size effect and synthesis condition. The permittivities of BaTiO 3 powder at different particle sizes were calculated, which predicted a maximum permittivity of over 16 000 around the room-temperature critical size of ∼70 nm. The prediction was in good accordance with the experimental data reported recently

  11. Physical and morphological properties of alumina powders synthesized through sol-gel method

    International Nuclear Information System (INIS)

    Julie Andrianny Murshidi; Choo Thye Foo; Che Seman Mahmood; Meor Yusof Meor Sulaiman

    2006-01-01

    Aluminum oxide powders were prepared by the hydrolysis of aluminum isopropoxide catalysed by hydrochloric acid and in the presence of Sodium Lauryl Sulphate C 1 2H 2 5NaO 4 S as a surface stabilizing agent. After ageing for 24 hours the gel-like products were filtered and calcined at 1200 degree C. The effect of initial concentration of the aluminum precursor, aluminum isopropoxide (0.2 M, 0.1 M, 0.05 M and 0.03 M) and ageing temperature of 28 degree C, 50 degree C, 70 degree C, 85 degree C and 95 degree C on particle size of the powder were studied using Particle Size Analyzer. Shape and morphology of the particles were characterized by using Scanning Electron Microscope (SEM). (Author)

  12. Thermoluminescence study of Mn doped lithium tetraborate powder and pellet samples synthesized by solution combustion synthesis

    International Nuclear Information System (INIS)

    Ozdemir, A.; Yegingil, Z.; Nur, N.; Kurt, K.; Tuken, T.; Depci, T.; Tansug, G.; Altunal, V.; Guckan, V.; Sigircik, G.; Yu, Y.; Karatasli, M.; Dolek, Y.

    2016-01-01

    In this paper, the thermoluminescence (TL) dosimetric characteristics under beta-ray, x-ray and gamma-ray excitations of powder and pellet Mn-doped lithium tetraborates (LTB) which were produced by solution combustion synthesis technique were investigated, and the results were compared with that of TLD-100 chips. The chemical composition and morphologies of the obtained LTB and Mn-doped LTB (LTB:Mn) were confirmed by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) and scanning electron microscopy (SEM) with EDX. LTB:Mn was studied using luminescence spectroscopy. In addition, the effects of sintering and annealing temperatures and times on the thermoluminescence (TL) properties of LTB:Mn were investigated. The glow curves of powder samples as well as pellet samples exposed to different beta doses exhibited a low temperature peak at about 100 °C followed by an intense principal high temperature peak at about 260 °C. The kinetic parameters (E, b, s) associated with the prominent glow peaks were estimated using T m –T stop , initial rise (IR) and computerized glow curve deconvolution (CGCD) methods. The TL response of integral TL output increased linearly with increasing the dose in the range of 0.1–10 Gy and was followed by a superlinearity up to 100 Gy both for powder and pellet samples using beta-rays. Powder and pellet LTB:Mn were irradiated to a known dose by a linear accelerator with 6 and 18 MV photon beams, 6–15 MeV electron beams and a traceable 137 Cs beam to investigate energy response. Further, TL sensitivity, fading properties and recycling effects related with beta exposure of LTB:Mn phosphor were evaluated and its relative energy response was also compared with that of TLD-100 chips. The comparison of the results showed that the obtained phosphors have good TL dose response with adequate sensitivity and linearity for the measurement of medical doses.

  13. Nanometric onion-like hollow spheres in laser synthesized boron nitride ultrafine powder

    Energy Technology Data Exchange (ETDEWEB)

    Boulanger, L; Willaime, F [CEA Centre d` Etudes de Saclay, 91 - Gif-sur-Yvette (France). Direction des Technologies Avancees; Cauchetier, M [CEA Centre d` Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. de Recherche sur l` Etat Condense, les Atomes et les Molecules

    1994-12-31

    TEM observations of ultra-fine B Cl{sub 3}-N H{sub 3} powders elaborated by an innovative method, laser pyrolysis, are presented. The resulting microstructures in the as received state and after thermal treatments show small nanometric scale configurations close to the ones met with carbon, such as an hollowed configuration of onions but at a much smaller scale than with carbon. 3 figs., 3 refs.

  14. Using precipitated Cr on the surface of Cu-Cr alloy powders as catalyst synthesizing CNTs/Cu composite powders by water-assisted CVD

    Science.gov (United States)

    Zhou, Honglei; Liu, Ping; Chen, Xiaohong; Bi, Liming; Zhang, Ke; Liu, Xinkuan; Li, Wei; Ma, Fengcang

    2018-02-01

    Given that the conventional catalyst is easily soluble in the matrix to result in the poor performance of the CNTs/Cu composite materials, the Cr nano-particles precipitated on the surface of Cu-Cr particles are first used as catalysts to prepare the CNTs/Cu composite powders by means of water-assisted chemical vapor deposition in situ synthesis. The results show that the morphological difference of the precipitated Cr nano-particle is obvious with the change of solution and aging treatment, and the morphology, length and diameter of the synthetic CNTs are also different. The catalyst of Cr nano-particle has the best morphology and the synthesized CNTs had a good wettability with Cu particles when the Cu-Cr composite powders was solution-treated at 1023 K for 60 min and then was aged at 723 K for 120 min. The length, diameter, yield and purity of the synthesized CNTs can be also affected by the moisture content in the reaction gas. It is the most suitable for the growth of CNTs when the moisture content is 0.4%, and the high purity and defect-free CNTs with the smooth pipe wall, a diameter of 20 ˜ 30 nm and a length of up to 1800 nm can be obtained. The yield of CNTs with the moisture content of 0.4% reached to 138%, which was increased by 119% to compare with that without moisture. In this paper, a feasible technology was offered for the preparation of high performance CNTs/Cu composites.

  15. Nanostructural Features of Silver Nanoparticles Powder Synthesized through Concurrent Formation of the Nanosized Particles of Both Starch and Silver

    Directory of Open Access Journals (Sweden)

    A. Hebeish

    2013-01-01

    Full Text Available Green innovative strategy was developed to accomplish silver nanoparticles formation of starch-silver nanoparticles (St-AgNPs in the powder form. Thus, St-AgNPs were synthesized through concurrent formation of the nanosized particles of both starch and silver. The alkali dissolved starch acts as reducing agent for silver ions and as stabilizing agent for the formed AgNPs. The chemical reduction process occurred in water bath under high-speed homogenizer. After completion of the reaction, the colloidal solution of AgNPs coated with alkali dissolved starch was cooled and precipitated using ethanol. The powder precipitate was collected by centrifugation, then washed, and dried; St-AgNPs powder was characterized using state-of-the-art facilities including UV-vis spectroscopy, Transmission Electron Microscopy (TEM, particle size analyzer (PS, Polydispersity index (PdI, Zeta potential (ZP, XRD, FT-IR, EDX, and TGA. TEM and XRD indicate that the average size of pure AgNPs does not exceed 20 nm with spherical shape and high concentration of AgNPs (30000 ppm. The results obtained from TGA indicates that the higher thermal stability of starch coated AgNPS than that of starch nanoparticles alone. In addition to the data obtained from EDX which reveals the presence of AgNPs and the data obtained from particle size analyzer and zeta potential determination indicate that the good uniformity and the highly stability of St-AgNPs.

  16. Phase evolution, mechanical and corrosion behavior of Fe(100-x) Ni(x) alloys synthesized by powder metallurgy

    Science.gov (United States)

    Singh, Neera; Parkash, Om; Kumar, Devendra

    2018-03-01

    In the present investigation, Fe(100-x) Ni(x) alloys (x = 10, 20, 30, 40 and 50 wt%) were synthesized through the evolution of γ-taenite and α-kamacite phases by powder metallurgy route using commercially available Fe and Ni powders. Mechanically mixed powders of Fe and Ni were compacted at room temperature and sintered at three different temperatures 1000, 1200 and 1250 °C for 1 h. Both Ni concentration and sintering temperature have shown a strong impact on the phase formation, tribological and electrochemical behavior. Micro structural study has shown the formation of taenite (γ-Fe,Ni) and kamacite (α-Fe,Ni) phases in the sintered specimens. An increase in Ni fraction resulted in formation of more taenite which reduces hardness and wear resistance of specimens. Increasing the sintering temperature decreased the defect concentration with enhanced taenite formation, aiding to higher densification. Taenite formed completely in Fe50Ni50 after sintering at 1250 °C. Tribological test revealed the maximum wear resistance for Fe70Ni30 specimen due to the presence of both kamacite and taenite in significant proportions. The formation of taenite as well as the decrease in defect concentration improves the corrosion resistance of the specimens significantly in 1M HCl solution. A maximum corrosion protection efficiency of around ∼87% was achieved in acidic medium for Fe50Ni50, sintered at 1250 °C.

  17. ELECTRON MICROSCOPIC INVESTIGATION OF YTTRIUM ALUMINUM GARNET POWDERS Y3AL5O12, SYNTHESIZED BY SOL–GEL METHOD

    Directory of Open Access Journals (Sweden)

    A. E. Baranchikov

    2015-09-01

    Full Text Available Subject of Study. The paper presents results of characterization for neodymium doped yttrium aluminum garnet nanopowders - YAG:Nd3+ by the method of scanning electronic microscopy. Method. Synthesis of YAG:Nd3+ was carried out by sol-gel method from nitrate or acetate - nitrate solutions with addition of some organic compounds and ammonia as well. Such substances were used as the source ones: oxides of neodymium and yttrium with the content of the basic substance equal to 99.999 %; organic compounds: citric acid with the content of the basic substance not less than 99.0 %; ethylene glycol (99.5%; the ammonium lauryl sulfate (99.0 %; urea (99.0 % of Alfa Aesar, Fluka, Aldrich companies. Oxides of yttrium and neodymium (5 at. % were dissolved in 50% acetic acid, nitrate aluminum was added with a view to the resulting product Y2,85Nd0,15Al5,0O12, the solution was stirred and heated to 60С before reaching its transparency and uniformity. The weight of the portion corresponding to the stoichiometry YAG was 2.0 g. 50 % aqueous solutions of organic substances or 5% NH4OH in a weight ratio of 1:1 to the weight of the garnet were added in aqueous solutions, placed into glass cups. The solutions were thoroughly mixed first using a conventional stirrer, then on ultrasonic installation with simultaneous 60 С heating for 2 hours. Drying of solutions to the consistency of a powder or a thick gel was carried out at 110 С. Then the samples were placed into platinum cups and annealed in a tube furnace at 950 - 1050 С for the period from 0.5 to 2 hours. Additional annealing of the powders in the air at 950 - 1060С were carried out for the purpose of powders clarifying for residual amorphous carbon removal. Main Results. The synthesized powder precursors and powders after annealing were examined using a polarizing microscope to identify anisotropic crystalline phases. X-ray analysis of the synthesized samples was carried out on a DRON - 4 and UDR - 63

  18. and α-Fe 2 O 3 nano powders synthesized by emulsion precipitation

    African Journals Online (AJOL)

    Nano crystals of γ-Fe2O3 (maghemite) were synthesized by emulsion precipitation method using kerosene as oil phase, SPAN- 80 (sorbitane monooleate) as the surfactant and sodium hydroxide as the precipitating agent. The characterization of the samples by FTIR (Fourier transform infra-red) and XRD (X-ray diffraction) ...

  19. Nanosized lead lanthanum titanate (PLT) ceramic powders synthesized by the oxidant peroxo method

    Energy Technology Data Exchange (ETDEWEB)

    Camargo, Emerson R. [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod.Washingtin Luis km 235, CP 676, Sao Carlos SP 13565-9905 (Brazil)], E-mail: camargo@ufscar.br; Barrado, Cristiano M. [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod.Washingtin Luis km 235, CP 676, Sao Carlos SP 13565-9905 (Brazil); Ribeiro, Caue [EMBRAPA Instrumentacao Agropecuaria, Rua XV de Novembro 1452, Sao Carlos SP 13560-970 (Brazil)], E-mail: caue@cnpdia.embrapa.br; Longo, Elson [Department of Biochemistry, Chemistry Institute of Araraquara, UNESP-Sao Paulo State University, Rua Francisco Degni, CP 355, Araraquara SP 14801-907 (Brazil)], E-mail: elson@iq.unesp.br; Leite, Edson R. [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod.Washingtin Luis km 235, CP 676, Sao Carlos SP 13565-9905 (Brazil)], E-mail: derl@power.ufscar.br

    2009-05-05

    For the first time it is reported the synthesis of lead titanate modified with rare earth by the oxidant-peroxo method (OPM). Lanthanum was added up to 20% in mol through the dissolution of lanthanum oxide in nitric acid, followed by the addition of a solution of lead and lanthanum nitrate into an aqueous solution of titanium peroxo complexes. The amorphous precipitate formed was heat-treated at different temperatures in the range from 400 to 900 deg. C for crystallization. Powders were characterized by Raman spectroscopy and X-ray diffraction. Tetragonal perovskite structure was observed for the samples up to 15% of lanthanum substitution and cubic perovskite for sample with 20% of lanthanum. Crystallographic domains calculated by Scherrer equation showing a probable suppression of the crystallite growth in function of lanthanum content. It was observed shifting to lower frequencies of Raman modes in the range between 100 and 400 cm{sup -1} and the vanishing of the A1(2TO) and E(1LO) modes could be attributed to transition phase from tetragonal to cubic. Electronic microscopy image revealed that the powders annealed at height temperature are spherical with sharp size distribution.

  20. Nanosized lead lanthanum titanate (PLT) ceramic powders synthesized by the oxidant peroxo method

    International Nuclear Information System (INIS)

    Camargo, Emerson R.; Barrado, Cristiano M.; Ribeiro, Caue; Longo, Elson; Leite, Edson R.

    2009-01-01

    For the first time it is reported the synthesis of lead titanate modified with rare earth by the oxidant-peroxo method (OPM). Lanthanum was added up to 20% in mol through the dissolution of lanthanum oxide in nitric acid, followed by the addition of a solution of lead and lanthanum nitrate into an aqueous solution of titanium peroxo complexes. The amorphous precipitate formed was heat-treated at different temperatures in the range from 400 to 900 deg. C for crystallization. Powders were characterized by Raman spectroscopy and X-ray diffraction. Tetragonal perovskite structure was observed for the samples up to 15% of lanthanum substitution and cubic perovskite for sample with 20% of lanthanum. Crystallographic domains calculated by Scherrer equation showing a probable suppression of the crystallite growth in function of lanthanum content. It was observed shifting to lower frequencies of Raman modes in the range between 100 and 400 cm -1 and the vanishing of the A1(2TO) and E(1LO) modes could be attributed to transition phase from tetragonal to cubic. Electronic microscopy image revealed that the powders annealed at height temperature are spherical with sharp size distribution.

  1. Formation of polycrystalline MgB2 synthesized by powder in sealed tube method with different initial boron phase

    Science.gov (United States)

    Yudanto, Sigit Dwi; Imaduddin, Agung; Kurniawan, Budhy; Manaf, Azwar

    2018-04-01

    Magnesium diboride, MgB2 is a new high critical temperature superconductor that discovered in the beginning of the 21st century. The MgB2 has a simple crystal structure and a high critical temperature, which can be manufactured in several forms like thin films, tapes, wires including bulk in the large scale. For that reason, the MgB2 has good prospects for various applications in the field of electronic devices. In the current work, we have explored the synthesis of MgB2 polycrystalline using powder in a sealed tube method. Different initial boron phase for the synthesized of MgB2 polycrystalline were used. These were, in addition to magnesium powders, crystalline boron, amorphous boron and combination both of them were respectively fitted in the synthesis. The raw materials were mixed in a stoichiometric ratio of Mg: B=1:2, ground using agate mortar, packed into stainless steel SS304. The pack was then sintered at temperature of 800°C for 2 hours in air atmosphere. Phase formation of MgB2 polycrystalline in difference of initial boron phase was characterized using XRD and SEM. Referring to the diffraction pattern and microstructure observation, MgB2 polycrystalline was formed, and the formation was effective when using the crystalline Mg and fully amorphous B as the raw materials. The critical temperature of the specimen was evaluated by the cryogenic magnet. The transition temperature of the MgB2 specimen synthesized using crystalline magnesium and full amorphous boron is 42.678 K (ΔTc = 0.877 K).

  2. Green synthesized gold nanoparticles decorated graphene oxide for sensitive determination of chloramphenicol in milk, powdered milk, honey and eye drops.

    Science.gov (United States)

    Karthik, R; Govindasamy, Mani; Chen, Shen-Ming; Mani, Veerappan; Lou, Bih-Show; Devasenathipathy, Rajkumar; Hou, Yu-Shen; Elangovan, A

    2016-08-01

    A simple and rapid green synthesis using Bischofia javanica Blume leaves as reducing agent was developed for the preparation of gold nanoparticles (AuNPs). AuNPs decorated graphene oxide (AuNPs/GO) was prepared and employed for the sensitive amperometric determination of chloramphenicol. The green biosynthesis requires less than 40s to reduce gold salts to AuNPs. The formations of AuNPs and AuNPs/GO were evaluated by scanning electron and atomic force microscopies, UV-Visible and energy dispersive X-ray spectroscopies, X-ray diffraction studies, and electrochemical methods. AuNPs/GO composite film modified electrode was fabricated and shown excellent electrocatalytic ability towards chloramphenicol. Under optimal conditions, the amperometric sensing platform has delivered wide linear range of 1.5-2.95μM, low detection limit of 0.25μM and high sensitivity of 3.81μAμM(-1)cm(-2). The developed sensor exhibited good repeatability and reproducibility, anti-interference ability and long-term storage stability. Practical feasibility of the sensor has been demonstrated in food samples (milk, powdered milk and honey) and pharmaceutical sample (eye drops). The green synthesized AuNPs/GO composite has great potential for analysis of food samples in food safety measures. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Nanocrystalline TiAl powders synthesized by high-energy ball milling: effects of milling parameters on yield and contamination

    International Nuclear Information System (INIS)

    Bhattacharya, Prajina; Bellon, Pascal; Averback, Robert S.; Hales, Stephen J.

    2004-01-01

    High-energy ball milling was employed to produce nanocrystalline Ti-Al powders. As sticking of the powders can be sufficiently severe to result in a near zero yield, emphasis was placed on varying milling conditions so as to increase the yield, while avoiding contamination of the powders. The effects of milling parameters such as milling tools, initial state of the powders and addition of process control agents (PCA's) were investigated. Cyclohexane, stearic acid and titanium hydride were used as PCA's. Milling was conducted either in a Cr-steel vial with C-steel balls, or in a tungsten carbide (WC) vial with WC balls, using either elemental or pre-alloyed powders. Powder samples were characterized using X-ray diffraction, scanning and transmission electron microscopy. In the absence of PCA's mechanical alloying in a WC vial and attrition milling in a Cr-steel vial were shown to lead to satisfactory yields, about 65-80%, without inducing any significant contamination of the powders. The results suggest that sticking of the powders on to the milling tools is correlated with the phase evolution occurring in these powders during milling

  4. Mechano-chemical Synthesizing of Specially Functional Powder%特殊功能粉体的机械化学合成

    Institute of Scientific and Technical Information of China (English)

    杨华明; 王淀佐; 等

    2001-01-01

    With Calcium phosphate primary and cacium hydride as the raw materials,study on synthesizing β-TCP ceramic powder by mechano-chemicl method was made.β-TCP bioceramic powder with an average particle size of 3.09 μm was synthesized by the mechano-chemical method of agitation grinding.As a result,the exesting difficult problem of the poor bioceramic performances caused by big-sized β-TCP powder was solved.The mechanisn of the reaction of mechano-chemical Synthesizing is discussed.%以磷酸二氢钙和氢氧化钙为原料,开展了机械化学法合成β-TCP陶瓷粉末的研究,采用搅拌磨机械化学法合成了平均粒径为3.09 μm的生物陶瓷粉末β-TCP,解决了目前由于β-TCP粉末粒径大、导致生物陶瓷性能差的难题。最后探讨了机械化学合成反应的机理。

  5. Morphological characterization of tungsten trioxide nano powders synthesized by Sol-Gel modified Pechini's method

    Energy Technology Data Exchange (ETDEWEB)

    Ghasemi, Leila; Jafari, Hassan, E-mail: jafari_h@yahoo.com [Department of Materials Engineering, Faculty of Mechanical Engineering, Shahid Rajaee Teacher Training University, Tehran (Iran, Islamic Republic of)

    2017-11-15

    Sol-gel modified Pechini's method was used to prepare WO{sub 3} nano powders using dicarboxylic acid and polyethylene glycol as the chelating agent and polymeric source, respectively. WO{sub 3} powders were first prepared by calcination of resin precursor at 550 deg C under various initial concentrations of metal ion (12.5-50 mmol), acid (125-500 mmol), a complexing agent (32-262 mmol), and polyethylene glycol (1-16.5 mmol) in the air atmosphere. The products were characterized using X-ray powder diffraction, field emission scanning electron microscopy, and energy dispersive spectroscopy. The results revealed that the WO{sub 3} nano powders prepared with different amounts of chelating agent and polyethylene glycol, crystallized in monoclinic phase. The nano powders were impurity-free due to the presence of the complexing agent and polyethylene glycol as carbon sources. Morphological evolution indicated that the nano powders evolved from rod-like to regular and spherical shapes, depending on complexing agent and polyethylene glycol amounts. Nano powders with an average particle size of approximately 58 nm and a narrow size distribution were obtained. (author)

  6. Morphological characterization of tungsten trioxide nano powders synthesized by Sol-Gel modified Pechini's method

    International Nuclear Information System (INIS)

    Ghasemi, Leila; Jafari, Hassan

    2017-01-01

    Sol-gel modified Pechini's method was used to prepare WO 3 nano powders using dicarboxylic acid and polyethylene glycol as the chelating agent and polymeric source, respectively. WO 3 powders were first prepared by calcination of resin precursor at 550 deg C under various initial concentrations of metal ion (12.5-50 mmol), acid (125-500 mmol), a complexing agent (32-262 mmol), and polyethylene glycol (1-16.5 mmol) in the air atmosphere. The products were characterized using X-ray powder diffraction, field emission scanning electron microscopy, and energy dispersive spectroscopy. The results revealed that the WO 3 nano powders prepared with different amounts of chelating agent and polyethylene glycol, crystallized in monoclinic phase. The nano powders were impurity-free due to the presence of the complexing agent and polyethylene glycol as carbon sources. Morphological evolution indicated that the nano powders evolved from rod-like to regular and spherical shapes, depending on complexing agent and polyethylene glycol amounts. Nano powders with an average particle size of approximately 58 nm and a narrow size distribution were obtained. (author)

  7. Kinetic and equilibrium studies of the removal of ammonium ions from aqueous solution by rice husk ash-synthesized zeolite Y and powdered and granulated forms of mordenite

    International Nuclear Information System (INIS)

    Yusof, Alias Mohd; Keat, Lee Kian; Ibrahim, Zaharah; Majid, Zaiton Abdul; Nizam, Nik Ahmad

    2010-01-01

    The removal of ammonium from aqueous solutions using zeolite NaY prepared from a local agricultural waste, rice husk ash waste was investigated and a naturally occurring zeolite mordenite in powdered and granulated forms was used as comparison. Zeolite NaY and mordenite were well characterized by powder X-ray diffraction (XRD), energy dispersive X-ray (EDX) analysis and the total cation exchange capacity (CEC). CEC of the zeolites were measured as 3.15, 1.46 and 1.34 meq g -1 for zeolite Y, powdered mordenite and granular mordenite, respectively. Adsorption kinetics and equilibrium data for the removal of NH 4 + ions were examined by fitting the experimental data to various models. Kinetic studies showed that the adsorption followed a pseudo-second-order reaction. The equilibrium pattern fits well with the Langmuir isotherm compared to the other isotherms. The monolayer adsorption capacity for zeolite Y (42.37 mg/g) was found to be higher than that powdered mordenite (15.13 mg/g) and granular mordenite (14.56 mg/g). Thus, it can be concluded that the low cost and economical rice husk ash-synthesized zeolite NaY could be a better sorbent for ammonium removal due to its rapid adsorption rate and higher adsorption capacity compared to natural mordenite.

  8. High power density cell using nanostructured Sr-doped SmCoO3 and Sm-doped CeO2 composite powder synthesized by spray pyrolysis

    Science.gov (United States)

    Shimada, Hiroyuki; Yamaguchi, Toshiaki; Suzuki, Toshio; Sumi, Hirofumi; Hamamoto, Koichi; Fujishiro, Yoshinobu

    2016-01-01

    High power density solid oxide electrochemical cells were developed using nanostructure-controlled composite powder consisting of Sr-doped SmCoO3 (SSC) and Sm-doped CeO2 (SDC) for electrode material. The SSC-SDC nano-composite powder, which was synthesized by spray pyrolysis, had a narrow particle size distribution (D10, D50, and D90 of 0.59, 0.71, and 0.94 μm, respectively), and individual particles were spherical, composing of nano-size SSC and SDC fragments (approximately 10-15 nm). The application of the powder to a cathode for an anode-supported solid oxide fuel cell (SOFC) realized extremely fine cathode microstructure and excellent cell performance. The anode-supported SOFC with the SSC-SDC cathode achieved maximum power density of 3.65, 2.44, 1.43, and 0.76 W cm-2 at 800, 750, 700, and 650 °C, respectively, using humidified H2 as fuel and air as oxidant. This result could be explained by the extended electrochemically active region in the cathode induced by controlling the structure of the starting powder at the nano-order level.

  9. Nano structural Features of Silver Nanoparticles Powder Synthesized through Concurrent Formation of the Nano sized Particles of Both Starch and Silver

    International Nuclear Information System (INIS)

    Hebeish, A.; El-Rafie, M.H.; El-Sheikh, M.A.; El-Naggar, M.E.

    2013-01-01

    Green innovative strategy was developed to accomplish silver nanoparticles formation of starch-silver nanoparticles (St-AgNPs) in the powder form. Thus, St-AgNPs were synthesized through concurrent formation of the nano sized particles of both starch and silver. The alkali dissolved starch acts as reducing agent for silver ions and as stabilizing agent for the formed AgNPs. The chemical reduction process occurred in water bath under high-speed homogenizer. After completion of the reaction, the colloidal solution of AgNPs coated with alkali dissolved starch was cooled and precipitated using ethanol. The powder precipitate was collected by centrifugation, then washed, and dried; St-AgNPs powder was characterized using state-of-the-art facilities including UV-vis spectroscopy, Transmission Electron Microscopy (TEM), particle size analyzer (PS), Polydispersity index (PdI), Zeta potential (ZP), XRD, FT-IR, EDX, and TGA. TEM and XRD indicate that the average size of pure AgNPs does not exceed 20 nm with spherical shape and high concentration of AgNPs (30000 ppm). The results obtained from TGA indicates that the higher thermal stability of starch coated AgNPS than that of starch nanoparticles alone. In addition to the data obtained from EDX which reveals the presence of AgNPs and the data obtained from particle size analyzer and zeta potential determination indicate that the good uniformity and the highly stability of St-AgNPs).

  10. Study on the Key Technology of High Purity Strontium Titanate Powder Synthesized from Oxalic Acid Co-sediment Precipitation

    Science.gov (United States)

    Bi, Xiaoguo; Dong, Yingnan; Li, Yingjie; Niu, Wei; Tang, Jian; Ding, Shuang; Li, Meiyang

    2017-09-01

    Oxalate coprecipitation is applied in this paper, high purity titanium tetrachloride, and after the purification of strontium chloride, match with a certain concentration of solution, oxalate and strontium chloride and titanium tetrachloride in 1.005:1.000 make strontium titanium mixture ratio, slowly under 60°C to join in oxalic acid solution, aging around 4 h, get oxygen titanium strontium oxalate (SrTiO(C2O4)2 • 4H2 ) precipitation, after washing, drying and other process made oxygen titanium strontium oxalate powder.

  11. Chevrel phases superconductive and ultrafine powders synthesis and characterization; Synthese et caracterisation de poudres ultrafines supraconductrices de phases de Chevrel

    Energy Technology Data Exchange (ETDEWEB)

    Even-Boudjada, S

    1994-12-01

    This work deals with the Chevrel phases superconductive and ultrafine powders synthesis and characterization. The first part of this study presents some new way of synthesis (precipitation, coprecipitation) of Chevrel phases precursors powders (PbS, SnS, MoS{sub 2}) and their characterizations (X-ray fluorescence analysis, ICP mass spectroscopy, scanning electron microscopy, transmission electron microscopy and laser granulometry). These new synthesis methods lead to quasi spherical morphology grains and very weak size grains (0.2 to 0.5 {mu}m) whereas the chemical preparation from the solid state elements gives very different morphology grains (small plates) with a size of 1 to 20 {mu}m. In the second part is shown the interest of the binary Mo{sub 6} S{sub 8} as precursor in the synthesis of ternary superconductive phases (Li, Ni, Cu, Pb). The last part presents the formation reaction of the phase PbMo{sub 6} S{sub 8} and its main chemical and physical properties. Thus some calorimetric measures associated with X-ray diffraction analysis have been realized and have allowed to understand the different reactions occurring during the PbMo{sub 6}S{sub 8} synthesis. (O.L.). 100 refs., figs., tabs.

  12. Synchrotron WAXS and XANES studies of silica (SiO2) powders synthesized from Indonesian natural sands

    International Nuclear Information System (INIS)

    Muchlis, Khairanissa; Fauziyah, Nur Aini; Pratapa, Suminar; Soontaranon, Siriwat; Limpirat, Wanwisa

    2017-01-01

    In this study, we have investigated polymorphic silica (SiO 2 ) powders using, Wide Angle X-ray Scattering (WAXS) and X-Ray Absorption Near Edge Spectroscopy (XANES), laboratory X-Ray Diffraction (XRD) instruments. The WAXS and XANES spectra were collected using synchrotron radiation at Synchrotron Light Research Institute (SLRI), Nakhon Ratchasima, Thailand. The silica powders were obtained by processing silica sand from Tanah Laut, South Kalimantan, Indonesia. Purification process of silica sand was done by magnetic separation and immersion with HCl. The purification step was needed to reduce impurity or undesirable non Si elements. Three polymorphs of silica were produced, i.e. amorphous phase (A), quartz (B), and cristobalite (C). WAXS profile for each phase was presented in terms of intensity vs. 2θ prior to analyses. Both XRD (λ CuKα =1.54056 Å) and WAXS (λ=1.09 Å) patttern show that (1) A sample contains no crystallites, (2) B sample is monophasic, contains only quartz, and (3) C sample contains cristobalite and trydimite. XRD quantitative analysis using Rietica gave 98,8 wt% cristobalite, while the associated WAXS data provided 98.7 wt% cristobalite. Si K-edge XANES spectra were measured at energy range 1840 to 1920 eV. Qualitatively, the pre-edge and edge features for all phases are similar, but their main peaks in the post-edge region are different. (paper)

  13. CH3 NH3 PbI3 and HC(NH2 )2 PbI3 Powders Synthesized from Low-Grade PbI2 : Single Precursor for High-Efficiency Perovskite Solar Cells.

    Science.gov (United States)

    Zhang, Yong; Kim, Seul-Gi; Lee, Do-Kyoung; Park, Nam-Gyu

    2018-05-09

    High-efficiency perovskite solar cells are generally fabricated by using highly pure (>99.99 %) PbI 2 mixed with an organic iodide in polar aprotic solvents. However, the use of such an expensive chemical may impede progress toward large-scale industrial applications. Here, we report on the synthesis of perovskite powders by using inexpensive low-grade (99 %) PbI 2 and on the photovoltaic performance of perovskite solar cells prepared from a powder-based single precursor. Pure APbI 3 [A=methylammonium (MA) or formamidinium (FA)] perovskite powders were synthesized by treating low-grade PbI 2 with MAI or FAI in acetonitrile at ambient temperature. The structural phase purity was confirmed by X-ray diffraction. The solar cell with a MAPbI 3 film prepared from the synthesized perovskite powder demonstrated a power conversion efficiency (PCE) of 17.14 %, which is higher than the PCE of MAPbI 3 films prepared by using both MAI and PbI 2 as precursors (PCE=13.09 % for 99 % pure PbI 2 and PCE=16.39 % for 99.9985 % pure PbI 2 ). The synthesized powder showed better absorption and photoluminescence, which were responsible for the better photovoltaic performance. For the FAPbI 3 powder, a solution with a yellow non-perovskite δ-FAPbI 3 powder synthesized at room temperature was found to lead to a black perovskite film, whereas a solution with the black perovskite α-FAPbI 3 powder synthesized at 150 °C was not transformed into a black perovskite film. The α↔δ transition between the powder and film was assumed to correlate with the difference in the iodoplumbates in the powder-dissolved solution. An average PCE of 17.21 % along with a smaller hysteresis [ΔPCE=PCE reverse -PCE forward )=1.53 %] was demonstrated from the perovskite solar cell prepared by using δ-FAPbI 3 powder; this PCE is higher than the average PCE of 17.05 % with a larger hysteresis (ΔPCE=2.71 %) for a device based on a conventional precursor solution dissolving MAI with high

  14. Structural, magnetic and gas sensing properties of nanosized copper ferrite powder synthesized by sol gel combustion technique

    Energy Technology Data Exchange (ETDEWEB)

    Sumangala, T.P.; Mahender, C. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Barnabe, A. [Université de Toulouse, Institut Carnot CIRIMAT – UMR CNRS-UPS-INP 5085, Université Paul Sabatier, Toulouse 31062 (France); Venkataramani, N. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Prasad, Shiva, E-mail: shiva.pd@gmail.com [Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India)

    2016-11-15

    Stoichiometric nano sized copper ferrite particles were synthesized by sol gel combustion technique. They were then calcined at various temperatures ranging from 300–800 °C and were either furnace cooled or quenched in liquid nitrogen. A high magnetisation value of 48.2 emu/g signifying the cubic phase of copper ferrite, was obtained for sample quenched to liquid nitrogen temperature from 800 °C. The ethanol sensing response of the samples was studied and a maximum of 86% response was obtained for 500 ppm ethanol in the case of a furnace cooled sample calcined at 800 °C. The chemical sensing is seen to be correlated with the c/a ratio and is best in the case of tetragonal copper ferrite. - Highlights: • One of the first study on ethanol sensing of cubic copper ferrite. • In-situ High temperature XRD done shows phase transition from cubic to tetragonal. • A non-monotonic increase in magnetization was seen with calcination temperature. • A response of 86% was obtained towards 500 ppm ethanol. • Tried to correlate sensing response and ion content in spinel structure.

  15. Characterization of Synthesized and Commercial Forms of Magnesium Stearate Using Differential Scanning Calorimetry, Thermogravimetric Analysis, Powder X-Ray Diffraction, and Solid-State NMR Spectroscopy.

    Science.gov (United States)

    Delaney, Sean P; Nethercott, Matthew J; Mays, Christopher J; Winquist, Nickolas T; Arthur, Donia; Calahan, Julie L; Sethi, Manish; Pardue, Daniel S; Kim, Junghyun; Amidon, Gregory; Munson, Eric J

    2017-01-01

    Magnesium stearate is the salt of a complex mixture of fatty acids, with the majority being stearate and palmitate. It has multiple crystalline forms and, potentially, an amorphous form. Magnesium stearate is used in the pharmaceutical manufacturing industry as a powder lubricant, and typically is added at low levels (∼1%) during the manufacturing process and blended for a relatively short time (∼5 min). Proper levels and mixing times are needed, as too short a mixing time or too small a quantity will result in improper lubrication, and too much can negatively impact dissolution rates. The complex mixture of multiple fatty acids and crystalline forms in magnesium stearate leads to variability between commercial sources, and switching between sources can impact both the amount of lubricant and mixing time needed for proper lubrication. In order to better understand the complex nature of magnesium stearate, a variety of analytical techniques were used to characterize both synthesized and commercial magnesium stearate samples. The results show that correlation among differential scanning calorimetry, thermogravimetric analysis, solid-state NMR spectroscopy, and other techniques provides a unique insight into the forms of magnesium stearate. Finally, the ability to monitor form changes of magnesium stearate in an intact tablet using solid-state NMR spectroscopy is shown. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  16. Morphological and structural characterization of the Zn0,9Mn0,1O powder synthesized by combustion reaction and Pechini

    International Nuclear Information System (INIS)

    Ribeiro, M.A.; Torquato, R.; Simoes, A.N.; Costa, A.C.F.M.; Gama, L.; Kiminami, R.H.G.A.

    2009-01-01

    Zinc oxide, due to the piezoelectric and electro-optical characteristics, is used in application such as, chemical sensor, varistor, transparent conductive thin film and DMS. The aim of this work is to evaluate and compare structural and morphological characteristics of nanometric powders of Zn 0,9 Mn 0,1 O prepared by chemical synthesis of combustion reaction and Pechini method. The powders were characterized by XRD, SEM and BET. The XRD data shown to both studied method the presence of ZnO phase with hexagonal structure and without second phase. The powder prepared by combustion reaction presented 9% of reduction in crystallinity and 42% of increase in surface area in comparison with the powder prepared by Pechini method. The morphological analysis of the powder showed that both method produce powders with soft agglomerates constituted by nano size particles. (author)

  17. Synthesis of Sc{sub 2}O{sub 3} powders for preparation of transparent ceramics; Synthese de poudres de Sc{sub 2}O{sub 3} destinees a l'elaboration d'une ceramique transparente

    Energy Technology Data Exchange (ETDEWEB)

    Bravo, A.C.; Longuet, L.; Autissier, D. [CEA Centre d' Etudes du Ripault, 37 - Tours (France); Baumard, J.F. [Laboratoire Science des Procedes Ceramiques et de Traitements de Surfaces, SPCTS, UMR CNRS 6638, 87 - Limoges (France)

    2007-07-01

    Different precursors have been prepared by precipitation from scandium nitrates salts using ammonium hydrogeno-carbonate as precipitating agent. The influence of the precipitation technique, of the preparation temperature and of the 'precipitating agent/Sc{sup 3+}' molar ratio on the characteristics (nature, grain size...) of the synthesized precursors has been observed. A heat treatment at 700 C of these precursors has allowed to obtain thin and homogeneous Sc{sub 2}O{sub 3} powders well adapted for transparent ceramics preparation. (O.M.)

  18. Microstructural study of Ce1-xGdxO2-δ (x = 0.1 and 0.2) nano crystallized powders synthesized by the polymeric precursor method

    International Nuclear Information System (INIS)

    Cela, B.; Macedo, D.A.; Souza, G.L.; Paskocimas, C.A.; Martinelli, A.E.; Nascimento, R.M.

    2009-01-01

    Gadolinia-doped ceria powders (Ce 1-x Gd x O 2-δ ) were prepared with substitution of 10 and 20% of the dopant element by the polymeric precursor method. This method makes possible the attainment of homogeny powder in molecular level, ideal to application in Solid Oxide Fuel Cell (SOFC) component. In this work, the particulated materials were calcinated in a range from 500 °C to 900 °C and structurally characterized by X-Ray Diffraction (XRD). The sintering behaviors of the compact samples were determined by dilatometric analyses. The results showed the method efficiency to attain monophasic nanopowder with cubic crystalline structure starting at 700 °C. The crystallite average size and crystalline parameter were determined by the Rietveld refinement method. (author)

  19. Effect of Milling Time on the Microstructure, Physical and Mechanical Properties of Al-Al2O3 Nanocomposite Synthesized by Ball Milling and Powder Metallurgy

    Directory of Open Access Journals (Sweden)

    Meysam Toozandehjani

    2017-10-01

    Full Text Available The effect of milling time on the morphology, microstructure, physical and mechanical properties of pure Al-5 wt % Al2O3 (Al-5Al2O3 has been investigated. Al-5Al2O3 nanocomposites were fabricated using ball milling in a powder metallurgy route. The increase in the milling time resulted in the homogenous dispersion of 5 wt % Al2O3 nanoparticles, the reduction of particle clustering, and the reduction of distances between the composite particles. The significant grain refining during milling was revealed which showed as a reduction of particle size resulting from longer milling time. X-Ray diffraction (XRD analysis of the nanocomposite powders also showed that designated ball milling contributes to the crystalline refining and accumulation of internal stress due to induced severe plastic deformation of the particles. It can be argued that these morphological and microstructural variations of nanocomposite powders induced by designated ball milling time was found to contribute to an improvement in the density, densification, micro-hardness (HV, nano-hardness (HN, and Young’s modulus (E of Al-5Al2O3 nanocomposites. HV, HN, and E values of nanocomposites were increased by ~48%, 46%, and 40%, after 12 h of milling, respectively.

  20. Effect of Milling Time on the Microstructure, Physical and Mechanical Properties of Al-Al2O3 Nanocomposite Synthesized by Ball Milling and Powder Metallurgy

    Science.gov (United States)

    Matori, Khamirul Amin; Ostovan, Farhad; Abdul Aziz, Sidek; Mamat, Md Shuhazlly

    2017-01-01

    The effect of milling time on the morphology, microstructure, physical and mechanical properties of pure Al-5 wt % Al2O3 (Al-5Al2O3) has been investigated. Al-5Al2O3 nanocomposites were fabricated using ball milling in a powder metallurgy route. The increase in the milling time resulted in the homogenous dispersion of 5 wt % Al2O3 nanoparticles, the reduction of particle clustering, and the reduction of distances between the composite particles. The significant grain refining during milling was revealed which showed as a reduction of particle size resulting from longer milling time. X-Ray diffraction (XRD) analysis of the nanocomposite powders also showed that designated ball milling contributes to the crystalline refining and accumulation of internal stress due to induced severe plastic deformation of the particles. It can be argued that these morphological and microstructural variations of nanocomposite powders induced by designated ball milling time was found to contribute to an improvement in the density, densification, micro-hardness (HV), nano-hardness (HN), and Young’s modulus (E) of Al-5Al2O3 nanocomposites. HV, HN, and E values of nanocomposites were increased by ~48%, 46%, and 40%, after 12 h of milling, respectively. PMID:29072632

  1. Effect of Milling Time on the Microstructure, Physical and Mechanical Properties of Al-Al₂O₃ Nanocomposite Synthesized by Ball Milling and Powder Metallurgy.

    Science.gov (United States)

    Toozandehjani, Meysam; Matori, Khamirul Amin; Ostovan, Farhad; Abdul Aziz, Sidek; Mamat, Md Shuhazlly

    2017-10-26

    The effect of milling time on the morphology, microstructure, physical and mechanical properties of pure Al-5 wt % Al₂O₃ (Al-5Al₂O₃) has been investigated. Al-5Al₂O₃ nanocomposites were fabricated using ball milling in a powder metallurgy route. The increase in the milling time resulted in the homogenous dispersion of 5 wt % Al₂O₃ nanoparticles, the reduction of particle clustering, and the reduction of distances between the composite particles. The significant grain refining during milling was revealed which showed as a reduction of particle size resulting from longer milling time. X-Ray diffraction (XRD) analysis of the nanocomposite powders also showed that designated ball milling contributes to the crystalline refining and accumulation of internal stress due to induced severe plastic deformation of the particles. It can be argued that these morphological and microstructural variations of nanocomposite powders induced by designated ball milling time was found to contribute to an improvement in the density, densification, micro-hardness ( HV ), nano-hardness ( HN ), and Young's modulus ( E ) of Al-5Al₂O₃ nanocomposites. HV , HN , and E values of nanocomposites were increased by ~48%, 46%, and 40%, after 12 h of milling, respectively.

  2. Extremely fine structured cathode for solid oxide fuel cells using Sr-doped LaMnO3 and Y2O3-stabilized ZrO2 nano-composite powder synthesized by spray pyrolysis

    Science.gov (United States)

    Shimada, Hiroyuki; Yamaguchi, Toshiaki; Sumi, Hirofumi; Nomura, Katsuhiro; Yamaguchi, Yuki; Fujishiro, Yoshinobu

    2017-02-01

    A solid oxide fuel cell (SOFC) for high power density operation was developed with a microstructure-controlled cathode using a nano-composite powder of Sr-doped LaMnO3 (LSM) and Y2O3-stabilized ZrO2 (YSZ) synthesized by spray pyrolysis. The individual LSM-YSZ nano-composite particles, formed by crystalline and amorphous nano-size LSM and YSZ particles, showed spherical morphology with uniform particle size. The use of this powder for cathode material led to an extremely fine microstructure, in which all the LSM and YSZ grains (approximately 100-200 nm) were highly dispersed and formed their own network structures. This microstructure was due to the two phase electrode structure control using the powder, namely, nano-order level in each particle and micro-order level between particles. An anode-supported SOFC with the LSM-YSZ cathode using humidified H2 as fuel and ambient air as oxidant exhibited high power densities, such as 1.29 W cm-2 under a voltage of 0.75 V and a maximum power density of 2.65 W cm-2 at 800 °C. Also, the SOFC could be stably operated for 250 h with no degradation, even at a high temperature of 800 °C.

  3. Effect of Co2+ and Y3+ ions insertion on the microstructure development and magnetic properties of Ni0.5Zn0.5Fe2O4 powders synthesized using Co-precipitation method

    Science.gov (United States)

    Rashad, M. M.; Rayan, D. A.; Turky, A. O.; Hessien, M. M.

    2015-01-01

    Nanocrystalline Ni0.5Zn0.5-xCoxFe2-zYzO4 powders (x=0-0.3 and z from 0 to 0.3) have been synthesized via a facile co-precipitation technique. X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) are utilized in order to study the effect of variation of cobalt and yttrium substitutions and its impact on crystalline size, lattice parameter, X-ray density, microstructure and magnetic properties of the formed powders. X-ray diffraction data indicated that, after doping, all samples consisted of the main spinel phase for the formed precursors precipitated at pH 10 annealed at 1000 oC for 2 h. The lattice parameter and the unit cell were decreased linearly with increasing Co content whereas they were increased with increasing the Y incorporation. Additionally, the porosity was increased with increasing Co concentration while it was decreased with increasing the Y insertion. The mean ionic radii and hopping and bond lengths was decreased with the value of Co2+ and they were increased with the value of Y3+ ion as well as both of Y3+ and Co2+ ions. The microstructures of the produced powders were found to be cubic like structure. The addition of Y3+ ion suppressed the grain size whereas addition of Co2+ ion enhanced the grain growth availably. An examination of the magnetic properties revealed an increase in saturation magnetization with increasing Co and Y concentrations incorporation up to x=0.3. Meanwhile, the formed powders exhibited superparamagnetic characteristics. A high saturation magnetization (77.0 emu/g) was achieved for Ni0.5Zn0.2Co0.3Fe2O4 sample annealed at 1000 oC for 2 h.

  4. Microstructural characterization and compression properties of TiC0.61/Cu(Al) composite synthesized from Cu and Ti3AlC2 powders

    International Nuclear Information System (INIS)

    Huang, Zhenying; Bonneville, Joel; Zhai, Hongxiang; Gauthier-Brunet, Veronique

    2014-01-01

    Highlights: • Submicro-layered TiC 0.61 /Cu(Al) nanocomposite. • MAX phase. • High yield stress. • Deformation mechanism. - Abstract: A new submicro-layered TiC 0.61 /Cu(Al) composite has been prepared by hot-pressing a mixture of 50 vol.% Ti 3 AlC 2 and 50 vol.% Cu powders at 1150 °C and 30 MPa. It is shown that the initial reinforcement Ti 3 AlC 2 particles have, after synthesis, an unusual microstructure, which consists of submicron-thick layers of TiC 0.61 and Cu(Al) alloy. Both the width of the TiC 0.61 and Cu(Al) layers are ∼150 nm. Thus, the Ti 3 AlC 2 particles are decomposed into the TiC 0.61 phase, while the additional Al atoms provided by Ti 3 AlC 2 diffuse into the molten Cu matrix at high temperature. Compression tests were performed at constant strain rate in the temperature range 20–800 °C. The new designed TiC 0.61 /Cu(Al) composite has both a high yield stress, σ 0.2 measured at 0.2% strain offset, and a high ultimate compressive strength, σ UCS , which is attributed to strong interface bonding between TiC 0.61 and Cu(Al) phase. For instance, at 20 and 200 °C, σ 0.2 is 770 MPa and 700 MPa, while σ UCS is 1.18 GPa and 1 GPa, respectively. Plastic deformation takes place in the Cu(Al) matrix. Wavy slip lines are observed indicating that cross-slip could be the dominant deformation mechanism

  5. Study of Y{sub 1−x}Er{sub x}FeO{sub 3} (0≤x≤1) powder synthesized by sol–gel method and their magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Man; Jiang, Guojian, E-mail: guojianjiang@sit.edu.cn; Yang, Wenqian; Duan, Li; Peng, Wei; Chen, Jiang; Wang, Xiaojian

    2016-11-01

    A series of single phase Y{sub 1−x}Er{sub x}FeO{sub 3} (0≤x≤1) orthoferrite samples were synthesized by sol-gel method and their magnetic properties were studied in detail. The prepared samples were characterized by X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and differential scanning calorimetry (DSC). The obviously weak ferromagnetic property, which caused by Dzialoshinski Moriya (DM) antisymmetric exchange mechanism, was observed in YFeO{sub 3} for the magnetization jump at H=0 Oe. The magnetization of YFeO{sub 3} was evidently changed by doping Er{sup 3+}. The increase of the Er{sup 3+} content in Y{sub 1−x}Er{sub x}FeO{sub 3} greatly enhanced the paramagnetic component and gradually decreased the ferromagnetic component. - Highlights: • We synthesized a series of single phase Y{sub 1−x}Er{sub x}FeO{sub 3} orthoferrite powder by sol–gel method. • We studied magnetic properties of Y{sub 1−x}Er{sub x}FeO{sub 3} (0≤x≤1) in detail. • The magnetization of YFeO{sub 3} was evidently changed by doping Er{sup 3+}.

  6. Magnetic properties of Sn-substituted Ni-Zn ferrites synthesized from nano-sized powders of NiO, ZnO, Fe2O3, and SnO2

    Science.gov (United States)

    Ali, MA; Uddin, MM; Khan, MNI; Chowdhury, FUZ; Hoque, SM; Liba, SI

    2017-06-01

    A series of Ni0.6-x/2Zn0.4-x/2Sn x Fe2O4 (x = 0.0, 0.05, 0.1, 0.15, 0.2, and 0.3) (NZSFO) ferrite composities have been synthesized from nano powders using a standard solid state reaction technique. The spinel cubic structure of the investigated samples has been confirmed by x-ray diffraction (XRD). The magnetic properties such as saturation magnetization ({M}{{s}}), remanent magnetization ({M}{{r}}), coercive field ({H}{{c}}), and Bohr magneton (μ) are calculated from the hysteresis loops. The value of {M}{{s}} is found to decrease with increasing Sn content in the samples. This change is successfully explained by the variation of A-B interaction strength due to Sn substitution in different sites. The compositional stability and quality of the prepared ferrite composites have also been endorsed by the fairly constant initial permeability ({μ }^{\\prime }) over a wide range of frequency. The decreasing trend of {μ }^{\\prime } with increasing Sn content has been observed. Curie temperature {T}{{C}} has been found to increase with the increase in Sn content. A wide spread frequency utility zone indicates that the NZSFO can be considered as a good candidate for use in broadband pulse transformers and wide band read-write heads for video recording. The composition of x = 0.05 shows unusual results and the possible reason is also mentioned with the established formalism.

  7. Microstructure and morphology of powder particles TiC-NiCr, synthesized in plasma jet, at high-energy actions on components of initial composition Ti-C-NiCr

    Science.gov (United States)

    Solonenko, Oleg P.; Smirnov, Andrey V.; Chesnokov, Anton E.

    2017-10-01

    The results of experiments on in-situ synthesis of the microspherical, in particular hollow, cermet powder TiC- 30vol.%NiCr at processing of the Ti-C-NiCr agglomerates in argon-helium plasma jet flowing out into controlled atmosphere are presented. Preparation of the agglomerates consisted of the following stages: (i) high-energy treatment of the initial powders Ti and NiCr in planetary mill with their subsequent uniform mixing with glass black powder, (ii) preparation of dough from mechanically mixed powders and binder, and their granulation using the extrusion method, (iii) drying and classification of granules by the sizes.

  8. Liquid phase surface melting of AA8011 aluminum alloy by addition of Al/Al{sub 2}O{sub 3} nano-composite powders synthesized by high-energy milling

    Energy Technology Data Exchange (ETDEWEB)

    Sohi, M. Heydarzadeh [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Hojjatzadeh, S.M.H., E-mail: Hojatzadeh@yahoo.com [Department of Welding, Science and Research Branch, Azad University, Tehran (Iran, Islamic Republic of); Moosavifar, Sh. S.; Heshmati-Manesh, S. [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

    2014-09-15

    Highlights: • Aluminum matrix composite layers reinforced with alumina particles were fabricated. • Non milled powders caused porosity in the microstructures because of poor wettability. • The ball milling of powders was significantly improved the wettability of nano ceramic particles. • The micro hardness of the layers was approximately 3 times greater than that of the base metal. - Abstract: Poor wettability of particles is an obstacle in formation of sound composite layer via surface melting. Pre-coating of particles with metallic material by different techniques, such as ball milling may enhance the wettability of the particles with molten metal. In this study, composite surface layers containing Al{sub 2}O{sub 3} particles were fabricated on the surface of AA8011 aluminum substrates by tungsten inert gas (TIG) surface melting using preplaced layers of Al/Al{sub 2}O{sub 3} powder mixtures in two different forms: (1) a mixture of 40 wt% Al and 60 wt% of 50 nm Al{sub 2}O{sub 3} powders and (2) a mixture obtained by mechanical alloying of 40 wt% Al and 60 wt% of 60 μm Al{sub 2}O{sub 3} powders. Morphology evolution of powders during ball milling and the microstructure of the fabricated composite layers were studied through conventional characterization techniques, such as optical microscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD). Microhardness measurements were also performed across the alloyed zone. The results indicated that the layer fabricated by the second route showed a defect free structure with a more uniform distribution of Al{sub 2}O{sub 3} particles in comparison with the layer obtained by the first route. It was also noticed that the uniform dispersion of Al{sub 2}O{sub 3} particles in the fabricated layer increased the hardness to 133 HV which was over 3 times of that of the base metal.

  9. (YSZ) powders

    Indian Academy of Sciences (India)

    Unknown

    109–114. © Indian Academy of Sciences. 109 ... Materials Science Division, Bhabha Atomic Research Centre, Mumbai 400 085, India .... pensions of 900°C calcined YSZ powders. .... The sintered density data of the compacts (sintered at.

  10. Development of nano-structured silicon carbide ceramics: from synthesis of the powder to sintered ceramics; Elaboration de ceramiques nanostructurees en carbure de silicium: de la synthese de la poudre a la ceramique frittee

    Energy Technology Data Exchange (ETDEWEB)

    Reau, A.

    2008-12-15

    The materials used inside future nuclear reactors will be subjected to very high temperature and neutrons flux. Silicon carbide, in the form of SiC{sub f}/SiC nano-structured composite is potentially interesting for this type of application. It is again necessary to verify the contribution of nano-structure on the behaviour of this material under irradiation. To verify the feasibility and determine the properties of the matrix, it was envisaged to produce it by powder metallurgy from SiC nanoparticles. The objective is to obtain a fully dense nano-structured SiC ceramic without additives. For that, a parametric study of the phases of synthesis and agglomeration was carried out, the objective of which is to determine the active mechanisms and the influence of the key parameters. Thus, studying the nano-powder synthesis by laser pyrolysis allowed to produce, with high production rates, homogeneous batches of SiC nanoparticles whose size can be adjusted between 15 and 90 nm. These powders have been densified by an innovating method: Spark Plasma Sintering (SPS). The study and the optimization of the key parameters allowed the densification of silicon carbide ceramic without sintering aids while preserving the nano-structure of material. The thermal and mechanical properties of final materials were studied in order to determine the influence of the microstructure on their properties. (author)

  11. Sysnthesis of powders by freeze-drying

    International Nuclear Information System (INIS)

    Johnson, S.M.; Gusman, M.I.; Hildenbrand, D.L.

    1988-01-01

    The freeze-drying method of synthesizing powders of the superconducting oxide YBa 2 Cu 3 O 7 - δ is described. This process produces homogeneous, submicron powders of high purity. The effects of salt selection, solution concentration and pH on the process are described. Some evaluation of the sintering behavior and the effects on critical current density are included

  12. Crystallization behavior of ZrO{sub 2}−3Y{sub 2}O{sub 3}−xSrO precursor powders synthesized by a coprecipitation process

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Hsueh-Liang [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta- Hsueh Road, Tainan 70101, Taiwan (China); Hwang, Weng-Sing [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta- Hsueh Road, Tainan 70101, Taiwan (China); Institute of Nanotechnology and Microsystems Engineering, National Cheng Kung University, 1 Ta- Hsueh Road, Tainan 70101, Taiwan (China); Du, Je-Kang [Department of Dentistry, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China); Department of Dentistry, Kaohsiung Medical University, Chung Ho Memorial Hospital, 100 Tzyou 1st Road, Kaohsiung 80708, Taiwan (China); Chen, Ker-Kong, E-mail: enamel@kmu.edu.tw [Department of Dentistry, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China); Department of Dentistry, Kaohsiung Medical University, Chung Ho Memorial Hospital, 100 Tzyou 1st Road, Kaohsiung 80708, Taiwan (China); Wang, Moo-Chin, E-mail: mcwang@kmu.edu.tw [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China)

    2016-09-05

    Crystallization behaviors of ZrO{sub 2}−3Y{sub 2}O{sub 3}−xSrO precursor powders were studied with zirconium nitrate (Zr(NO{sub 3}){sub 4}·xH{sub 2}O), yttrium nitrate (Y(NO{sub 3}){sub 3}·6H{sub 2}O) and strontium nitrate (Sr(NO{sub 3}){sub 2}) constituting the initial materials. Differential thermal analysis (DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), nano beam electron diffraction (NBED) and high-resolution TEM (HRTEM) were utilized to characterize the crystallization behavior of ZrO{sub 2}−3Y{sub 2}O{sub 3}−xSrO precursor powders. The activation energies of tetragonal ZrO{sub 2} (t-ZrO{sub 2}) crystallization were 389.1, 327.6, and 315.1 kJ/mol with SrO content for 1, 2, and 3 mol%, respectively, obtained with a non-isothermal method. The growth morphology parameter and growth mechanism index were close to 2.0 and 1.0, respectively, showing that t-ZrO{sub 2} had a plate-like morphology. - Highlights: • The single phase of tetragonal ZrO{sub 2} formed when calcined at 923 K for 2 h. • ZrO{sub 2}−3Y{sub 2}O{sub 3}−2SrO precursor powders crystallization is at 765.6 K. • The activation energy of t-ZrO{sub 2} crystallization was 389.1 kJ/mol with 1 mol% SrO. • The growth morphology and index of crystallization were close to 2.0 and 1.0.

  13. Elaboration of silicon carbides nano particles (SiC): from the powder synthesis to the sintered ceramic; Elaboration de ceramiques nanostructurees en carbure de silicium (SiC): de la synthese de poudre a la ceramique frittee

    Energy Technology Data Exchange (ETDEWEB)

    Reau, A. [CEA Saclay, Dept. des Materiaux pour le Nucleaire (DEN/DANS/DMN/SRMA), 91 - Gif-sur-Yvette (France)

    2008-07-01

    Materials for the reactor cores of the fourth generation will need materials supporting high temperatures with fast neutrons flux. SiC{sub f}/SiC ceramics are proposed. One of the possible elaboration process is to fill SiC fiber piece with nano particles SiC powder and to strengthen by sintering. The aim of this thesis is to obtain a nano structured SiC ceramic as a reference for the SiC{sub f}/SiC composite development and to study the influence of the fabrication parameters. (A.L.B.)

  14. Synthesis, Structure, and Rigid Unit Mode-like Anisotropic Thermal Expansion of BaIr2In9.

    Science.gov (United States)

    Calta, Nicholas P; Han, Fei; Kanatzidis, Mercouri G

    2015-09-08

    This Article reports the synthesis of large single crystals of BaIr2In9 using In flux and their characterization by variable-temperature single-crystal and synchrotron powder X-ray diffraction, resistivity, and magnetization measurements. The title compound adopts the BaFe2Al9-type structure in the space group P6/mmm with room temperature unit cell parameters a = 8.8548(6) Å and c = 4.2696(4) Å. BaIr2In9 exhibits anisotropic thermal expansion behavior with linear expansion along the c axis more than 3 times larger than expansion in the ab plane between 90 and 400 K. This anisotropic expansion originates from a rigid unit mode-like mechanism similar to the mechanism of zero and negative thermal expansion observed in many anomalous thermal expansion materials such as ZrW2O8 and ScF3.

  15. Effects of calcination temperature on phase formation and particle size of Zn{sub 2}Nb{sub 34}O{sub 87} powder synthesized by solid-state reaction

    Energy Technology Data Exchange (ETDEWEB)

    Amonpattaratkit, Penphitcha, E-mail: p.amonpattaratkit@gmail.com [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Ananta, Supon, E-mail: suponananta@yahoo.com [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2013-05-15

    The solid-state mixed oxide method via a rapid vibro-milling technique was explored for the preparation of single-phase Zn{sub 2}Nb{sub 34}O{sub 87} nanopowders. Phase formation of zinc niobate was investigated as a function of calcination temperature by using a combination of thermogravimetric/differential thermal analyzer (TG/DTA) and X-ray diffraction (XRD) techniques. Morphology, particle size and chemical composition of the powders were determined by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) technique. The obtained results clearly revealed the influences of calcination temperature on phase formation and particle size of Zn{sub 2}Nb{sub 34}O{sub 87} nanopowder. - Highlights: ► Single phase Zn{sub 2}Nb{sub 34}O{sub 87} was firstly prepared by solid-state mixed oxide method via a rapid vibro-milling technique. ► The influences of calcination temperature on phase formation and particle size were investigated. ► Zn{sub 2}Nb{sub 34}O{sub 87} powders were characterized by TG–DTA, XRD, SEM and EDX.

  16. Powder diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Hart, M.

    1995-12-31

    the importance of x-ray powder diffraction as an analytical tool for phase identification of materials was first pointed out by Debye and Scherrer in Germany and, quite independently, by Hull in the US. Three distinct periods of evolution lead to ubiquitous application in many fields of science and technology. In the first period, until the mid-1940`s, applications were and developed covering broad categories of materials including inorganic materials, minerals, ceramics, metals, alloys, organic materials and polymers. During this formative period, the concept of quantitative phase analysis was demonstrated. In the second period there followed the blossoming of technology and commercial instruments became widely used. The history is well summarized by Parrish and by Langford and Loueer. By 1980 there were probably 10,000 powder diffractometers in routine use, making it the most widely used of all x-ray crystallographic instruments. In the third, present, period data bases became firmly established and sophisticated pattern fitting and recognition software made many aspects of powder diffraction analysis routine. High resolution, tunable powder diffractometers were developed at sources of synchrotron radiation. The tunability of the spectrum made it possible to exploit all the subtleties of x-ray spectroscopy in diffraction experiments.

  17. Powder diffraction

    International Nuclear Information System (INIS)

    Hart, M.

    1995-01-01

    The importance of x-ray powder diffraction as an analytical tool for phase identification of materials was first pointed out by Debye and Scherrer in Germany and, quite independently, by Hull in the US. Three distinct periods of evolution lead to ubiquitous application in many fields of science and technology. In the first period, until the mid-1940's, applications were and developed covering broad categories of materials including inorganic materials, minerals, ceramics, metals, alloys, organic materials and polymers. During this formative period, the concept of quantitative phase analysis was demonstrated. In the second period there followed the blossoming of technology and commercial instruments became widely used. The history is well summarized by Parrish and by Langford and Loueer. By 1980 there were probably 10,000 powder diffractometers in routine use, making it the most widely used of all x-ray crystallographic instruments. In the third, present, period data bases became firmly established and sophisticated pattern fitting and recognition software made many aspects of powder diffraction analysis routine. High resolution, tunable powder diffractometers were developed at sources of synchrotron radiation. The tunability of the spectrum made it possible to exploit all the subtleties of x-ray spectroscopy in diffraction experiments

  18. Powder diffractometry

    International Nuclear Information System (INIS)

    Doucet, J.

    1983-01-01

    The new possibilities openned by the synchrotron radiation in the powder diffractometry techniques are presented. This technique is described in a general manner and some aspects which can be developed with the use of the synchrotron radiation are analyzed. (L.C.) [pt

  19. Powder technology

    International Nuclear Information System (INIS)

    Agueda, Horacio

    1989-01-01

    Powder technology is experiencing nowadays a great development and has broad application in different fields: nuclear energy, medicine, new energy sources, industrial and home artifacts, etc. Ceramic materials are of daily use as tableware and also in the building industry (bricks, tiles, etc.). However, in machine construction its utilization is not so common. The same happens with metals: powder metallurgy is employed less than traditional metal forming techniques. Both cases deal with powder technology and the forming techniques as far as the final consolidation through sintering processes are very similar. There are many different methods and techniques in the forming stage: cold-pressing, slip casting, injection molding, extrusion molding, isostatic pressing, hot-pressing (which involves also the final consolidation step), etc. This variety allows to obtain almost any desired form no matter how complex it could be. Some applications are very specific as in the case of UO 2 pellets (used as nuclear fuels) but with the same technique and other materials, it is possible to manufacture a great number of different products. This work shows the characteristics and behaviour of two magnetic ceramic materials (ferrites) fabricated in the laboratory of the Applied Research Division of the Bariloche Atomic Center for different purposes. Other materials and products made with the same method are also mentioned. Likewise, densities and shrinkage obtained by different methods of forming (cold-pressing, injection molding, slip casting and extrusion molding) using high-purity alumina (99.5% Al 2 O 3 ). Finally, different applications of such methods are given. (Author) [es

  20. Microstructural characterization and compression properties of TiC{sub 0.61}/Cu(Al) composite synthesized from Cu and Ti{sub 3}AlC{sub 2} powders

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhenying, E-mail: zhyhuang@bjtu.edu.cn [Institute of Material Science and Engineering, School of Mechanical and Electronic Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Institut PPRIME, Département de Physique et Mécanique des Matériaux, CNRS, Université de Poitiers, ENSMA, UPR 3346, SP2MI, Téléport 2 Boulevard Marie et Pierre Curie, BP 30179, F86962 Futuroscope Chasseneuil Cedex (France); Bonneville, Joel [Institut PPRIME, Département de Physique et Mécanique des Matériaux, CNRS, Université de Poitiers, ENSMA, UPR 3346, SP2MI, Téléport 2 Boulevard Marie et Pierre Curie, BP 30179, F86962 Futuroscope Chasseneuil Cedex (France); Zhai, Hongxiang [Institute of Material Science and Engineering, School of Mechanical and Electronic Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Gauthier-Brunet, Veronique [Institut PPRIME, Département de Physique et Mécanique des Matériaux, CNRS, Université de Poitiers, ENSMA, UPR 3346, SP2MI, Téléport 2 Boulevard Marie et Pierre Curie, BP 30179, F86962 Futuroscope Chasseneuil Cedex (France); and others

    2014-07-25

    Highlights: • Submicro-layered TiC{sub 0.61}/Cu(Al) nanocomposite. • MAX phase. • High yield stress. • Deformation mechanism. - Abstract: A new submicro-layered TiC{sub 0.61}/Cu(Al) composite has been prepared by hot-pressing a mixture of 50 vol.% Ti{sub 3}AlC{sub 2} and 50 vol.% Cu powders at 1150 °C and 30 MPa. It is shown that the initial reinforcement Ti{sub 3}AlC{sub 2} particles have, after synthesis, an unusual microstructure, which consists of submicron-thick layers of TiC{sub 0.61} and Cu(Al) alloy. Both the width of the TiC{sub 0.61} and Cu(Al) layers are ∼150 nm. Thus, the Ti{sub 3}AlC{sub 2} particles are decomposed into the TiC{sub 0.61} phase, while the additional Al atoms provided by Ti{sub 3}AlC{sub 2} diffuse into the molten Cu matrix at high temperature. Compression tests were performed at constant strain rate in the temperature range 20–800 °C. The new designed TiC{sub 0.61}/Cu(Al) composite has both a high yield stress, σ{sub 0.2} measured at 0.2% strain offset, and a high ultimate compressive strength, σ{sub UCS}, which is attributed to strong interface bonding between TiC{sub 0.61} and Cu(Al) phase. For instance, at 20 and 200 °C, σ{sub 0.2} is 770 MPa and 700 MPa, while σ{sub UCS} is 1.18 GPa and 1 GPa, respectively. Plastic deformation takes place in the Cu(Al) matrix. Wavy slip lines are observed indicating that cross-slip could be the dominant deformation mechanism.

  1. Effect of Co{sup 2+} and Y{sup 3+} ions insertion on the microstructure development and magnetic properties of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} powders synthesized using Co-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Rashad, M.M., E-mail: rashad133@yahoo.com [Central Metallurgical Research and Development Institute (CMRDI), P.O. Box 87, Helwan 11421, Cairo (Egypt); Rayan, D.A.; Turky, A.O. [Central Metallurgical Research and Development Institute (CMRDI), P.O. Box 87, Helwan 11421, Cairo (Egypt); Hessien, M.M. [Central Metallurgical Research and Development Institute (CMRDI), P.O. Box 87, Helwan 11421, Cairo (Egypt); Chemistry Department, Taif University (Saudi Arabia)

    2015-01-15

    Nanocrystalline Ni{sub 0.5}Zn{sub 0.5−x}Co{sub x}Fe{sub 2−z}Y{sub z}O{sub 4} powders (x=0–0.3 and z from 0 to 0.3) have been synthesized via a facile co-precipitation technique. X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) are utilized in order to study the effect of variation of cobalt and yttrium substitutions and its impact on crystalline size, lattice parameter, X-ray density, microstructure and magnetic properties of the formed powders. X-ray diffraction data indicated that, after doping, all samples consisted of the main spinel phase for the formed precursors precipitated at pH 10 annealed at 1000 {sup o}C for 2 h. The lattice parameter and the unit cell were decreased linearly with increasing Co content whereas they were increased with increasing the Y incorporation. Additionally, the porosity was increased with increasing Co concentration while it was decreased with increasing the Y insertion. The mean ionic radii and hopping and bond lengths was decreased with the value of Co{sup 2+} and they were increased with the value of Y{sup 3+} ion as well as both of Y{sup 3+} and Co{sup 2+} ions. The microstructures of the produced powders were found to be cubic like structure. The addition of Y{sup 3+} ion suppressed the grain size whereas addition of Co{sup 2+} ion enhanced the grain growth availably. An examination of the magnetic properties revealed an increase in saturation magnetization with increasing Co and Y concentrations incorporation up to x=0.3. Meanwhile, the formed powders exhibited superparamagnetic characteristics. A high saturation magnetization (77.0 emu/g) was achieved for Ni{sub 0.5}Zn{sub 0.2}Co{sub 0.3}Fe{sub 2}O{sub 4} sample annealed at 1000 {sup o}C for 2 h. - Highlights: • Ni{sub 0.5}Zn{sub 0.5−x}Co{sub x}Fe{sub 2−z}Y{sub z}O{sub 4} powders were synthesized. • The porosity decreases with Y{sup 3+} and increases with Co{sup 2+}. • The bond lengths decrease with Co{sup 2

  2. Synthesis of battery grade reduced silver powder

    International Nuclear Information System (INIS)

    Qadeer, R.; Hameed, M.; Ikram, S.; Munir, A.

    2002-01-01

    Process for production of battery grade reduced silver powder, an active positive material for zinc-silver oxide batteries, having specific characteristics has been optimized and the synthesized reduced silver powder was characterized. Results reveal that the values of bulk density (1.25 0.1 g/cm3) and activity (73.27 %) of synthesized reduced silver powder lies within the recommended range for use as battery material. It has purity ≥ 98% and contains Fe and Cu as traces in the concentration range of 30 5 ppm and 15 7 ppm respectively. Others determined values of surface and pores parameters are: surface area 2.6 .4 m2/g: pore volume 3.10 cm3/g: pore diameter 0.043 mu m and porosity 20%. XRD studies reveal that reduced silver powder has a cubic structure. (author)

  3. Structural study of (N{sub 2}H{sub 5},H){sub 2.9}U{sub 1.1}Ce{sub 0.9}(C{sub 2}O{sub 4}){sub 5}·10H{sub 2}O from a conventional X-ray diffraction diagram obtained on a powder synthesized by a fast vortex process

    Energy Technology Data Exchange (ETDEWEB)

    Brackx, E., E-mail: Emmanuelle.brackx@cea.fr [CEA, DEN, DTEC, SGCS, LMAC, Marcoule, 30207 Bagnols sur Cèze (France); Laval, J.P. [Centre Européen de la Céramique, SPCTS, UMR-CNRS 7315, Université de Limoges, Faculté des Sciences, 12 rue Atlantis, 87068 Limoges (France); Dugne, O. [CEA, DEN, DTEC, SGCS, LMAC, Marcoule, 30207 Bagnols sur Cèze (France); Feraud, J.P. [CEA, DEN, DTEC, SGCS, LGCI, Marcoule, 30207 Bagnols sur Cèze (France); Arab-Chapelet, B. [CEA, DEN, DRCP, SCPS, LC2A, Marcoule, 30207 Bagnols sur Cèze (France)

    2015-01-15

    In the context of research on U/minor actinides for nuclear fuel reprocessing in the transmutation process, developments are first studied with surrogates containing uranium and lanthanides to facilitate testing. The tests consist of precipitating and calcining a hydrazinium uranium/cerium oxalate. The structure of this oxalate had not been previously determined, but was necessary to validate the physicochemical mechanisms involved. The present study, firstly demonstrates the structural similarity of the U/Ce oxalate phase (N{sub 2}H{sub 5},H){sub 2.9}U{sub 1.1}Ce{sub 0.9}(C{sub 2}O{sub 4}){sub 5}·10H{sub 2}O, synthesized using a vortex precipitator for continuous synthesis of actinide oxalates, with previously known oxalates, crystallizing in P6{sub 3}/mmc symmetry, obtained by more classical methods. This fast precipitation process induces massive nucleation of fine powders. Their structural and microstructural determination confirms that the raw and dried phases belong to the same structural family as (NH{sub 4}){sub 2}U{sub 2}(C{sub 2}O{sub 4}){sub 5}·0.7H{sub 2}O whose structure was described by Chapelet-Arab in P6{sub 3}/mmc symmetry, using single crystal data. However, they present an extended disorder inside the tunnels of the structure, even after drying at 100 °C, between water and hydrazinium ions. This disorder is directly related to the fast vortex method. This structure determination can be used as a basis for further semi-quantitative analysis on the U/minor actinides products formed under various experimental conditions. - Highlights: • Uranium cerium oxalate precipitate characterization by X-ray powder diffraction. • Morphology characterization by SEM analysis. • Structure determination by unit cell Rietveld refinement.

  4. CVD carbon powders modified by ball milling

    Directory of Open Access Journals (Sweden)

    Kazmierczak Tomasz

    2015-09-01

    Full Text Available Carbon powders produced using a plasma assisted chemical vapor deposition (CVD methods are an interesting subject of research. One of the most interesting methods of synthesizing these powders is using radio frequency plasma. This method, originally used in deposition of carbon films containing different sp2/sp3 ratios, also makes possible to produce carbon structures in the form of powder. Results of research related to the mechanical modification of these powders have been presented. The powders were modified using a planetary ball mill with varying parameters, such as milling speed, time, ball/powder mass ratio and additional liquids. Changes in morphology and particle sizes were measured using scanning electron microscopy and dynamic light scattering. Phase composition was analyzed using Raman spectroscopy. The influence of individual parameters on the modification outcome was estimated using statistical method. The research proved that the size of obtained powders is mostly influenced by the milling speed and the amount of balls. Powders tend to form conglomerates sized up to hundreds of micrometers. Additionally, it is possible to obtain nanopowders with the size around 100 nm. Furthermore, application of additional liquid, i.e. water in the process reduces the graphitization of the powder, which takes place during dry milling.

  5. Synthesis and characterization of superconducting YBCO powder

    International Nuclear Information System (INIS)

    Praveen, B.; Karki, T.; Krishnamoorthi, J.

    2008-01-01

    Full text: Superconducting yttrium barium copper oxide power has been synthesized through solid state sintering method - milling and sintering - using Y 2 O 3 , BaCo 3 and CuO powders. XRD result of the milled and sintered powder reveals that the powder that has formed contains YBa 2 Cu 3 O 6.5 superconducting phase. Results obtained by SEM/EDAX show the distribution of the different elements. Experiments carried out by intermediate firing and final annealing in oxygen controlled atmosphere show the diffusion of oxygen in preformed YBa 2 Cu 3 O 6.5 and their results are discussed

  6. Foundations of powder metallurgy

    International Nuclear Information System (INIS)

    Libenson, G.A.

    1987-01-01

    Consideration is being given to physicochemical foundations and technology of metal powders, moulding and sintering of bars, made of them or their mixtures with nonmetal powders. Data on he design of basic equipment used in the processes of powder metallurgy and its servicing are presented. General requirements of safety engineering when fabricating metal powders and products of them are mentioned

  7. Fundamentals of powder metallurgy

    International Nuclear Information System (INIS)

    Khan, I.H.; Qureshi, K.A.; Minhas, J.I.

    1988-01-01

    This book is being presented to introduce the fundamentals of technology of powder metallurgy. An attempt has been made to present an overall view of powder metallurgy technology in the first chapter, whereas chapter 2 to 8 deal with the production of metal powders. The basic commercial methods of powder production are briefly described with illustrations. Chapter 9 to 12 describes briefly metal powder characteristics and principles of testing, mixing, blending, conditioning, compaction and sintering. (orig./A.B.)

  8. Characterization of combustion synthesized zirconia powder by UV ...

    Indian Academy of Sciences (India)

    Unknown

    The present study describes synthesis of nanocrystalline ... 2.3 Surface acidity and basicity determination. The total ..... Arul Dhas N and Patil K C 1994 Int. J. Self-Propag. High- ... West R C and Astle M J (eds) 1980 CRC handbook of chemistry.

  9. Production of nanocrystalline metal powders via combustion reaction synthesis

    Science.gov (United States)

    Frye, John G.; Weil, Kenneth Scott; Lavender, Curt A.; Kim, Jin Yong

    2017-10-31

    Nanocrystalline metal powders comprising tungsten, molybdenum, rhenium and/or niobium can be synthesized using a combustion reaction. Methods for synthesizing the nanocrystalline metal powders are characterized by forming a combustion synthesis solution by dissolving in water an oxidizer, a fuel, and a base-soluble, ammonium precursor of tungsten, molybdenum, rhenium, or niobium in amounts that yield a stoichiometric burn when combusted. The combustion synthesis solution is then heated to a temperature sufficient to substantially remove water and to initiate a self-sustaining combustion reaction. The resulting powder can be subsequently reduced to metal form by heating in a reducing gas environment.

  10. Morphological and structural characterization of the Zn{sub 0,9}Mn{sub 0,1}O powder synthesized by combustion reaction and Pechini; Caracterizacao estrutural e morfologica de pos de Zn{sub 0,9}Mn{sub 0,1}O sintetizados por reacao de combustao e metodo Pechini

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, M A; Torquato, R; Simoes, A N; Costa, A C.F.M.; Gama, L [Universidade Federal de Campina Grande (DEMA/UFCG), PB (Brazil). Dept. de Engenharia dos Materiais; Kiminami, R H.G.A. [Universidade Federal de Sao Carlos (DEMA/UFSCar), SP (Brazil). Dept. de Engenharia de Materiais

    2009-07-01

    Zinc oxide, due to the piezoelectric and electro-optical characteristics, is used in application such as, chemical sensor, varistor, transparent conductive thin film and DMS. The aim of this work is to evaluate and compare structural and morphological characteristics of nanometric powders of Zn{sub 0,9}Mn{sub 0,1}O prepared by chemical synthesis of combustion reaction and Pechini method. The powders were characterized by XRD, SEM and BET. The XRD data shown to both studied method the presence of ZnO phase with hexagonal structure and without second phase. The powder prepared by combustion reaction presented 9% of reduction in crystallinity and 42% of increase in surface area in comparison with the powder prepared by Pechini method. The morphological analysis of the powder showed that both method produce powders with soft agglomerates constituted by nano size particles. (author)

  11. Aluminum powder metallurgy processing

    Energy Technology Data Exchange (ETDEWEB)

    Flumerfelt, J.F.

    1999-02-12

    The objective of this dissertation is to explore the hypothesis that there is a strong linkage between gas atomization processing conditions, as-atomized aluminum powder characteristics, and the consolidation methodology required to make components from aluminum powder. The hypothesis was tested with pure aluminum powders produced by commercial air atomization, commercial inert gas atomization, and gas atomization reaction synthesis (GARS). A comparison of the GARS aluminum powders with the commercial aluminum powders showed the former to exhibit superior powder characteristics. The powders were compared in terms of size and shape, bulk chemistry, surface oxide chemistry and structure, and oxide film thickness. Minimum explosive concentration measurements assessed the dependence of explosibility hazard on surface area, oxide film thickness, and gas atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization oxidation of aluminum powder. An Al-Ti-Y GARS alloy exposed in ambient air at different temperatures revealed the effect of reactive alloy elements on post-atomization powder oxidation. The pure aluminum powders were consolidated by two different routes, a conventional consolidation process for fabricating aerospace components with aluminum powder and a proposed alternative. The consolidation procedures were compared by evaluating the consolidated microstructures and the corresponding mechanical properties. A low temperature solid state sintering experiment demonstrated that tap densified GARS aluminum powders can form sintering necks between contacting powder particles, unlike the total resistance to sintering of commercial air atomization aluminum powder.

  12. Sol-gel synthesis and densification of aluminoborosilicate powders. Part 1: Synthesis

    Science.gov (United States)

    Bull, Jeffrey; Selvaduray, Guna; Leiser, Daniel

    1992-01-01

    Aluminoborosilicate powders high in alumina content were synthesized by the sol-gel process utilizing various methods of preparation. Properties and microstructural effects related to these syntheses were examined. After heating to 600 C for 2 h in flowing air, the powders were amorphous with the metal oxides comprising 87 percent of the weight and uncombusted organics the remainder. DTA of dried powders revealed a T(sub g) at approximately 835 C and an exotherm near 900 C due to crystallization. Powders derived from aluminum secbutoxide consisted of particles with a mean diameter 5 microns less than those from aluminum isopropoxide. Powders synthesized with aluminum isopropoxide produced agglomerates comprised of rod shaped particulates while powders made with the secbutoxide precursor produced irregular glassy shards. Compacts formed from these powders required different loadings for equivalent densities according to the method of synthesis.

  13. Preparation of nanosize carbon powders by pulsed wire discharge

    Energy Technology Data Exchange (ETDEWEB)

    Minami, C.; Kinemuchi, Y.; Suzuki, T.; Suematsu, H.; Jiang, W.; Yatsui, K. [Nagaoka Univ. of Technology, Extreme Energy-Density Research Inst., Nagaoka, Niigata (Japan); Hirata, T.; Hatakeyama, R. [Tohoku Univ., Graduate School of Engineering, Sendai, Miyagi (Japan)

    2002-06-01

    Nanosize powders of carbons were tried to be synthesized by pulsed discharge of graphite wires in several kinds of ambient gases. When the wire was discharged in N{sub 2} gas, nanosize powders have been successfully produced. The result of X-ray diffraction analysis indicated that nanosize powders produced in N{sub 2} gas at 750 Torr were amorphous carbon containing glassy carbons, while mass-spectrum analysis demonstrated the production of fullerenes at 600 Torr. If the wire is discharged in Ar gas, dielectric breakdown takes place between electrodes, producing no carbon powders. (author)

  14. Spherical rhenium metal powder

    International Nuclear Information System (INIS)

    Leonhardt, T.; Moore, N.; Hamister, M.

    2001-01-01

    The development of a high-density, spherical rhenium powder (SReP) possessing excellent flow characteristics has enabled the use of advanced processing techniques for the manufacture of rhenium components. The techniques that were investigated were vacuum plasma spraying (VPS), direct-hot isostatic pressing (D-HIP), and various other traditional powder metallurgy processing methods of forming rhenium powder into near-net shaped components. The principal disadvantages of standard rhenium metal powder (RMP) for advanced consolidation applications include: poor flow characteristics; high oxygen content; and low and varying packing densities. SReP will lower costs, reduce processing times, and improve yields when manufacturing powder metallurgy rhenium components. The results of the powder characterization of spherical rhenium powder and the consolidation of the SReP are further discussed. (author)

  15. Hydrothermal treatment of coprecipitated YSZ powders

    International Nuclear Information System (INIS)

    Arakaki, Alexander Rodrigo; Yoshito, Walter Kenji; Ussui, Valter; Lazar, Dolores Ribeiro Ricci

    2009-01-01

    Zirconia stabilized with 8.5 mol% yttria (YSZ) were synthesized by coprecipitation and resulting gels were hydrothermally treated at 200°C and 220 PSI for 4, 8 and 16 hours. Products were oven dried at 70°C for 24 hours, uniaxially pressed as pellets and sintered at 1500 °C for 1 hour. Powders were characterized for surface area with N 2 gas adsorption, X-ray diffraction, laser diffraction granulometric analysis and scanning and transmission electronic microscopy. Density of ceramics was measured by an immersion method based on the Archimedes principle. Results showed that powders dried at 70°C are amorphous and after treatment has tetragonal/cubic symmetry. Surface area of powders presented a significant reduction after hydrothermal treatment. Ceramics prepared from hydrothermally treated powders have higher green density but sintered pellets are less dense when compared to that made with powders calcined at 800°C for 1 hour due to the agglomerate state of powders. Solvothermal treatment is a promising procedure to enhance density. (author)

  16. SAF line powder operations

    International Nuclear Information System (INIS)

    Frederickson, J.R.; Horgos, R.M.

    1983-10-01

    An automated nuclear fuel fabrication line is being designed for installation in the Fuels and Materials Examination Facility (FMEF) near Richland, Washington. The fabrication line will consist of seven major process systems: Receiving and Powder Preparation; Powder Conditioning; Pressing and Boat Loading; Debinding, Sintering, and Property Adjustment; Boat Transport; Pellet Inspection and Finishing; and Pin Operations. Fuel powder processing through pellet pressing will be discussed in this paper

  17. Two layer powder pressing

    International Nuclear Information System (INIS)

    Schreiner, H.

    1979-01-01

    First, significance and advantages of sintered materials consisting of two layers are pointed out. By means of the two layer powder pressing technique metal powders are formed resulting in compacts with high accuracy of shape and mass. Attributes of basic powders, different filling methods and pressing techniques are discussed. The described technique is supposed to find further applications in the field of two layer compacts in the near future

  18. Operation whey powder

    International Nuclear Information System (INIS)

    Brunner, E.

    1987-01-01

    The odyssey of the contaminated whey powder finally has come to an end, and the 5000 tonnes of whey now are designated for decontamination by means of an ion exchange technique. The article throws light upon the political and economic reasons that sent the whey powder off on a chaotic journey. It is worth mentioning in this context that the natural radioactivity of inorganic fertilizers is much higher than that of the whey powder in question. (HP) [de

  19. Pharmaceutical powder compaction technology

    National Research Council Canada - National Science Library

    Çelik, Metin

    2011-01-01

    ... through the compaction formulation process and application. Compaction of powder constituents both active ingredient and excipients is examined to ensure consistent and reproducible disintegration and dispersion profiles...

  20. Biaxially textured articles formed by powder metallurgy

    Science.gov (United States)

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2003-08-05

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of ternary mixtures consisting of: Ni powder, Cu powder, and Al powder, Ni powder, Cr powder, and Al powder; Ni powder, W powder and Al powder; Ni powder, V powder, and Al powder; Ni powder, Mo powder, and Al powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100} orientation texture; and further having a Curie temperature less than that of pure Ni.

  1. Characterization of nano-crystalline ZrO{sub 2} synthesized via reactive plasma processing

    Energy Technology Data Exchange (ETDEWEB)

    Jayakumar, S., E-mail: sjayakumar.physics@gmail.com [Research and Development Centre, Bharathiar University, Coimbatore 641 014 (India); Ananthapadmanabhan, P.V. [Laser and Plasma Technology Division, BARC, Trombay, Mumbai 400 085 (India); Perumal, K. [Department of Physics, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641 020 India (India); Thiyagarajan, T.K. [Laser and Plasma Technology Division, BARC, Trombay, Mumbai 400 085 (India); Mishra, S.C. [Department of Metallurgical and Materials Engg, National Institute of Technology, Rourkela 769 008 (India); Su, L.T.; Tok, A.I.Y.; Guo, J. [School of Materials Science and Engg, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639 798 (Singapore)

    2011-07-25

    Highlights: > Direct conversion of micron-sized zirconium hydride powder to nanocrystalline ZrO{sub 2} powder. > The experimental approach uses reactive plasma processing technique. > The product has been characterized by various analytical tools to support the findings. - Abstract: Nano-crystalline ZrO{sub 2} powder has been synthesized via reactive plasma processing. The synthesized ZrO{sub 2} powders were characterized by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM) and FTIR spectroscopy. The synthesized powder consists of a mixture of tetragonal and monoclinic phases of zirconia. Average crystallite size calculated from the XRD pattern shows that particles with crystallite size 20 nm or less than 20 nm are in tetragonal phase, whereas particles greater than 20 nm are in the monoclinic phase. TEM results show that particles have spherical morphology with maximum percentage of particles distributed in a narrow size from about 15 nm to 30 nm.

  2. Sintered aluminium powders

    International Nuclear Information System (INIS)

    Stepanova, M.G.; Matveev, B.I.

    1974-01-01

    The mechanical and physical properties of aluminium powder alloys and the various methods employed to produce them are considered. Data are given on the hardening of the alloys SAP and SPAK-4, as well as the powder-alloy system Al-Cr-Zr. (L.M.)

  3. Bioactive nanocrystalline wollastonite synthesized by sol–gel ...

    Indian Academy of Sciences (India)

    The sol–gel combustion method was employed to synthesize the nanocrystalline wollastonite by taking the raw eggshell powder as a calcium source and TEOS as a source of silicate. Glycine was .... 94·37% CaCO3, hence in order to prepare 1 M Ca2+ ion solu- ... requires an acid or base catalyst hence the pH of the solu-.

  4. Bioactive nanocrystalline wollastonite synthesized by sol–gel ...

    Indian Academy of Sciences (India)

    The sol–gel combustion method was employed to synthesize the nanocrystalline wollastonite by taking the raw eggshell powder as a calcium source and TEOS as a source of silicate. Glycine was used as a reductant or fuel and nitrate ions present in metal nitrate acts as an oxidizer. The phase purity of the wollastonite was ...

  5. Freeze drying vs microwave drying–methods for synthesis of sinteractive thoria powders

    Energy Technology Data Exchange (ETDEWEB)

    Annie, D.; Chandramouli, V. [Materials Chemistry Division, Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 602103 (India); Anthonysamy, S., E-mail: sas@igcar.gov.in [Materials Chemistry Division, Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 602103 (India); Ghosh, Chanchal; Divakar, R. [Materials Synthesis and Structural Characterization Division, Materials and Metallurgy Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 602103 (India)

    2017-02-15

    Thoria powders were synthesized by oxalate precipitation from an aqueous solution of the nitrate. The filtered precipitates were freeze dried or microwave dried before being calcined at 1073 K. The thoria powders obtained were characterized for crystallite size, specific surface area, bulk density, particle size distribution and residual carbon. Microstructure of the product was studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Sinterability of the synthesized powders was studied by measuring the density of the sintered compacts. Powders that can be consolidated and sintered to densities ∼96% theoretical density (TD) at 1773 K were obtained.

  6. Doped-carbon composites, synthesizing methods and applications of the same

    Science.gov (United States)

    Viswanathan, Tito

    2017-05-09

    A method of synthesizing a doped carbon composite includes preparing a solution having a carbon source material and a heteroatom containing additive, evaporating the solution to yield a plurality of powders, and subjecting the plurality of powders to a heat treatment for a duration of time effective to produce the doped carbon composite.

  7. Measurement of loose powder density

    International Nuclear Information System (INIS)

    Akhtar, S.; Ali, A.; Haider, A.; Farooque, M.

    2011-01-01

    Powder metallurgy is a conventional technique for making engineering articles from powders. Main objective is to produce final products with the highest possible uniform density, which depends on the initial loose powder characteristics. Producing, handling, characterizing and compacting materials in loose powder form are part of the manufacturing processes. Density of loose metallic or ceramic powder is an important parameter for die design. Loose powder density is required for calculating the exact mass of powder to fill the die cavity for producing intended green density of the powder compact. To fulfill this requirement of powder metallurgical processing, a loose powder density meter as per ASTM standards is designed and fabricated for measurement of density. The density of free flowing metallic powders can be determined using Hall flow meter funnel and density cup of 25 cm/sup 3/ volume. Density of metal powders like cobalt, manganese, spherical bronze and pure iron is measured and results are obtained with 99.9% accuracy. (author)

  8. PULSE SYNTHESIZING GENERATOR

    Science.gov (United States)

    Kerns, Q.A.

    1963-08-01

    >An electronlc circuit for synthesizing electrical current pulses having very fast rise times includes several sinewave generators tuned to progressively higher harmonic frequencies with signal amplitudes and phases selectable according to the Fourier series of the waveform that is to be synthesized. Phase control is provided by periodically triggering the generators at precisely controlled times. The outputs of the generators are combined in a coaxial transmission line. Any frequency-dependent delays that occur in the transmission line can be readily compensated for so that the desired signal wave shape is obtained at the output of the line. (AEC)

  9. POWDER COAT APPLICATIONS

    Science.gov (United States)

    The report discusses an investigation of critical factors that affect the use of powder coatings on the environment, cost, quality, and production. The investigation involved a small business representative working with the National Defense Center for Environmental Excellence (ND...

  10. OIL SOLUTIONS POWDER

    Science.gov (United States)

    Technical product bulletin: aka OIL SOLUTIONS POWDER, SPILL GREEN LS, this miscellaneous oil spill control agent used in cleanups initially behaves like a synthetic sorbent, then as a solidifier as the molecular microencapsulating process occurs.

  11. Magnetically responsive enzyme powders

    Energy Technology Data Exchange (ETDEWEB)

    Pospiskova, Kristyna, E-mail: kristyna.pospiskova@upol.cz [Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Safarik, Ivo, E-mail: ivosaf@yahoo.com [Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Department of Nanobiotechnology, Institute of Nanobiology and Structural Biology of GCRC, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic)

    2015-04-15

    Powdered enzymes were transformed into their insoluble magnetic derivatives retaining their catalytic activity. Enzyme powders (e.g., trypsin and lipase) were suspended in various liquid media not allowing their solubilization (e.g., saturated ammonium sulfate and highly concentrated polyethylene glycol solutions, ethanol, methanol, 2-propanol) and subsequently cross-linked with glutaraldehyde. Magnetic modification was successfully performed at low temperature in a freezer (−20 °C) using magnetic iron oxides nano- and microparticles prepared by microwave-assisted synthesis from ferrous sulfate. Magnetized cross-linked enzyme powders were stable at least for two months in water suspension without leakage of fixed magnetic particles. Operational stability of magnetically responsive enzymes during eight repeated reaction cycles was generally without loss of enzyme activity. Separation of magnetically modified cross-linked powdered enzymes from reaction mixtures was significantly simplified due to their magnetic properties. - Highlights: • Cross-linked enzyme powders were prepared in various liquid media. • Insoluble enzymes were magnetized using iron oxides particles. • Magnetic iron oxides particles were prepared by microwave-assisted synthesis. • Magnetic modification was performed under low (freezing) temperature. • Cross-linked powdered trypsin and lipase can be used repeatedly for reaction.

  12. Characteristics of Inconel Powders for Powder-Bed Additive Manufacturing

    Directory of Open Access Journals (Sweden)

    Quy Bau Nguyen

    2017-10-01

    Full Text Available In this study, the flow characteristics and behaviors of virgin and recycled Inconel powder for powder-bed additive manufacturing (AM were studied using different powder characterization techniques. The results revealed that the particle size distribution (PSD for the selective laser melting (SLM process is typically in the range from 15 μm to 63 μm. The flow rate of virgin Inconel powder is around 28 s·(50 g−1. In addition, the packing density was found to be 60%. The rheological test results indicate that the virgin powder has reasonably good flowability compared with the recycled powder. The inter-relation between the powder characteristics is discussed herein. A propeller was successfully printed using the powder. The results suggest that Inconel powder is suitable for AM and can be a good reference for researchers who attempt to produce AM powders.

  13. Biaxially textured articles formed by powder metallurgy

    Science.gov (United States)

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2003-07-29

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100} orientation texture; and further having a Curie temperature less than that of pure Ni.

  14. Souper: A Synthesizing Superoptimizer

    OpenAIRE

    Sasnauskas, Raimondas; Chen, Yang; Collingbourne, Peter; Ketema, Jeroen; Lup, Gratian; Taneja, Jubi; Regehr, John

    2017-01-01

    If we can automatically derive compiler optimizations, we might be able to sidestep some of the substantial engineering challenges involved in creating and maintaining a high-quality compiler. We developed Souper, a synthesizing superoptimizer, to see how far these ideas might be pushed in the context of LLVM. Along the way, we discovered that Souper's intermediate representation was sufficiently similar to the one in Microsoft Visual C++ that we applied Souper to that compiler as well. Shipp...

  15. Comparative sinterability of combustion synthesized and commercial titanium carbides

    International Nuclear Information System (INIS)

    Manley, B.W.

    1984-11-01

    The influence of various parameters on the sinterability of combustion synthesized titanium carbide was investigaged. Titanium carbide powders, prepared by the combustion synthesis process, were sintered in the temperature range 1150 to 1600 0 C. Incomplete combustion and high oxygen contents were found to be the cause of reduced shrinkage during sintering of the combustion syntheized powders when compared to the shrinkage of commercial TiC. Free carbon was shown to inhibit shrinkage. The activation energy for sintering was found to depend on stoichiometry (C/Ti). With decreasing C/Ti, the rate of sintering increased. 29 references, 16 figures, 13 tables

  16. Zirconium dioxide ultrafine powders formation in ultra-high frequency discharge plasma

    International Nuclear Information System (INIS)

    Triotskij, V.N.; Kurkin, E.N.; Torbov, V.I.; Berestenko, V.I.; Torbova, O.D.; Gurov, S.V.; Alekseev, N.V.

    1995-01-01

    ZrO 2 fine powders of 30...60 nm particle size were synthesized by ZrCl 4 oxidation in a flow of oxygen microwave plasma. Oxygen flow rate and ZrCl 4 feeding rate were the defining parameters effecting on powder particles size at constant discharge power.At predominant contribution of the coalescence process into ZrO 2 powder particles formation their heterogeneous growth was shown necessary to take into account. 16 refs.; 5 figs

  17. Preparation of copper and silicon/copper powders by a gas ...

    Indian Academy of Sciences (India)

    Pure and silicon-coated metal copper nano to submicron-sized powders were prepared by gas evaporation and condensation. This powder was synthesized by using an industrial electron accelerator, ELV-6, with Ar as the carrier gas. Vapour from the liquefied metal surface was transferred to the cold zone by the carrier ...

  18. Ultrafine hydrogen storage powders

    Science.gov (United States)

    Anderson, Iver E.; Ellis, Timothy W.; Pecharsky, Vitalij K.; Ting, Jason; Terpstra, Robert; Bowman, Robert C.; Witham, Charles K.; Fultz, Brent T.; Bugga, Ratnakumar V.

    2000-06-13

    A method of making hydrogen storage powder resistant to fracture in service involves forming a melt having the appropriate composition for the hydrogen storage material, such, for example, LaNi.sub.5 and other AB.sub.5 type materials and AB.sub.5+x materials, where x is from about -2.5 to about +2.5, including x=0, and the melt is gas atomized under conditions of melt temperature and atomizing gas pressure to form generally spherical powder particles. The hydrogen storage powder exhibits improved chemcial homogeneity as a result of rapid solidfication from the melt and small particle size that is more resistant to microcracking during hydrogen absorption/desorption cycling. A hydrogen storage component, such as an electrode for a battery or electrochemical fuel cell, made from the gas atomized hydrogen storage material is resistant to hydrogen degradation upon hydrogen absorption/desorption that occurs for example, during charging/discharging of a battery. Such hydrogen storage components can be made by consolidating and optionally sintering the gas atomized hydrogen storage powder or alternately by shaping the gas atomized powder and a suitable binder to a desired configuration in a mold or die.

  19. Electrochemical behaviors of wax-coated Li powder/Li 4Ti 5O 12 cells

    Science.gov (United States)

    Park, Han Eol; Seong, Il Won; Yoon, Woo Young

    The wax-coated Li powder specimen was effectively synthesized using the drop emulsion technique (DET). The wax layer on the powder was verified by SEM, Focused Ion Beam (FIB), EDX and XPS. The porosity of a sintered wax-coated Li electrode was measured by linear sweep voltammetry (LSV) and compared with that of a bare, i.e., un-coated Li electrode. The electrochemical behavior of the wax-coated Li powder anode cell was examined by the impedance analysis and cyclic testing methods. The cyclic behavior of the wax-coated Li powder anode with the Li 4Ti 5O 12 (LTO) cathode cell was examined at a constant current density of 0.35 mA cm -2 with the cut-off voltages of 1.2-2.0 V at 25 °C. Over 90% of the initial capacity of the cell remained even after the 300th cycle. The wax-coated Li powder was confirmed to be a stable anode material.

  20. Weighing fluidized powder

    International Nuclear Information System (INIS)

    Adomitis, J.T.; Larson, R.I.

    1980-01-01

    Fluidized powder is discharged from a fluidizing vessel into a container. Accurate metering is achieved by opening and closing the valve to discharge the powder in a series of short-duration periods until a predetermined weight is measured by a load cell. The duration of the discharge period may be increased in inverse proportion to the amount of powder in the vessel. Preferably the container is weighed between the discharge periods to prevent fluctuations resulting from dynamic effects. The gas discharged into the container causes the pressures in the vessel and container to equalize thereby decreasing the rate of discharge and increasing the accuracy of metering as the weight reaches the predetermined value. (author)

  1. Functional coordination polymers and MOFs from reactions of the lanthanides and barium with azole ligands. Synthesis and characterization with a focus on structure determination from X-ray powder diffraction data; Funktionale Koordinationspolymere und MOFs aus Reaktionen der Lanthanide und des Bariums mit Azol-Liganden. Synthese und Charakterisierung mit dem Fokus der Strukturbestimmung anhand von Roentgenpulverbeugungsdaten

    Energy Technology Data Exchange (ETDEWEB)

    Rybak, Jens-Christoph

    2012-07-01

    This thesis deals with the synthesis and characterization of coordination polymers and MOFs of the lanthanides and barium with different azolic N-heterocycles. A total of 18 new organic-inorganic hybrid materials, as well as a series of co-doped compounds is presented. Besides the structural characterization of these materials from X-ray diffraction powder data, the focus of the investigations is on the thermal and photoluminescence spectroscopic properties. The lanthanides La - Lu, except Eu and Pm, can be reacted with 1H-1,2,3-triazole to give the series of the isotypic dense 3D-MOFs {sup 3}{sub ∞}[Ln(Tz{sup *}){sub 3}]. Investigation of the photoluminescence properties of these compounds reveals a broad range of different luminescence phenomena, including the first observation of an intrinsic inner-filter effect of the Ln{sup 3+}-ions. The structure of this isotypic series of compounds was solved and refined from X-ray powder diffraction data. A 2D-polymorph of these compounds {sup 2}{sub ∞}[Ln(Tz{sup *}){sub 3}], is observed for Ln = Sm, Tb and was characterized by single crystal data. The reaction of Eu with 1H-benzotriazole yields the 1D-coordination polymer {sup 1}{sub ∞}[Eu(Btz){sub 2}(BtzH){sub 2}], which is the first example of a divalent rare earth benzotriazolate. Analysis of the thermal properties reveals the transformation to the 3D-MOF {sup 3}{sub ∞}[Eu(Btz){sub 2}] at higher temperatures. The structure of this material was also solved from X-ray powder diffraction data. Investigation of the photoluminescence properties of the co-doped compounds {sup 3}{sub ∞}[Ba{sub 1-x}Eu{sub x}(Im){sub 2}], which were obtained from reaction of the salt-like hydrides BaH{sub 2} and EuH{sub 2} with imidazole, show that the synthesis of luminescent MOF materials by co-doping of non-luminescent networks with luminescence centers is possible. The structure of these materials was solved from X-ray powder diffraction data of the undoped compound {sup 3}{sub

  2. Baking Powder Wars

    OpenAIRE

    Civitello, Linda

    2017-01-01

    How did a mid-nineteenth century American invention, baking powder, replace yeast as a leavening agent and create a culinary revolution as profound as the use of yeast thousands of years ago?The approach was two-pronged and gendered: business archives, U.S. government records and lawsuits revealed how baking powder was created, marketed, and regulated. Women’s diaries and cookbooks—personal, corporate, community, ethnic—from the eighteenth century to internet blogs showed the use women made o...

  3. Some characteristics of urea-formaldehyde powder adhesives

    Directory of Open Access Journals (Sweden)

    Miljković Jovan

    2006-01-01

    Full Text Available Urea-formaldehyde (UF glue resins were the most important type of adhesives in the wood industry last 60 years, especially for the production of wood based panels. More convenient spray dried UF powders went into use last two decades. Small and medium private wood processing plants in Serbia prefer to use such powder adhesives, since they are more convenient for small capacity production. There is no production of UF powder resin in Serbia so necessary quantities are imported from abroad including producers from Asia. However, their characteristics are variable, dependent on syntheses steps and not well known among users. Objective of this research was to determine conveniences and lacks in application of two imported UF powder resins in comparison to domestic UF emulsion.

  4. Study on the sterilization of egg white powder by irradiation

    International Nuclear Information System (INIS)

    Fu Lixin; Meng Lifen; Zhao Xiaonan; Xu Dechun; Hu Shaoxin; Chen Changdong; Pei Ying

    2012-01-01

    The article studied the killing microorganism result, the influence of main essential nutrient and sense organ of egg white powder by Co-60 γ-ray irradiation. The microorganism index of the egg white powder samples can meet the government food sanitation standard by 4 kGy irradiation, and the killing microorganism rare can reach 100%. The irradiation dose from 4 to 10 kGy has little influence to the egg white powder protein, crude fiber and amino acids contras ting to comparison, and the sensory quality such as color and luster, scent has little change below 6 kGy irradiation. Synthesizing the results of physical chemistry and sense organ, the optimal irradiation dose of egg white powder killing microorganism is 4 to 6 kGy. (authors)

  5. Widely tunable THz synthesizer

    Science.gov (United States)

    Hindle, F.; Mouret, G.; Eliet, S.; Guinet, M.; Cuisset, A.; Bocquet, R.; Yasui, T.; Rovera, D.

    2011-09-01

    The generation of cw-THz radiation by photomixing is particularly suited to the high resolution spectroscopy of gases; nevertheless, until recently, it has suffered from a lack of frequency metrology. Frequency combs are a powerful tool that can transfer microwave frequency standards to optical frequencies and a single comb has permitted accurate (10-8) THz frequency synthesis with a limited tuning range. A THz synthesizer composed of three extended cavity laser diodes phase locked to a frequency comb has been constructed and its utility for high resolution gas phase spectroscopy demonstrated. The third laser diode allows a larger tuning range of up to 300 MHz to be achieved without the need for large frequency excursions, while the frequency comb provides a versatile link to be established from any traceable microwave frequency standard. The use of a single frequency comb as a reference for all of the cw-lasers eliminates the dependency of synthesized frequency on the carrier envelope offset frequency. This greatly simplifies the frequency comb stabilization requirements and leads to a reduced instrument complexity.

  6. SYNTH: A spectrum synthesizer

    International Nuclear Information System (INIS)

    Hensley, W.K.; McKinnon, A.D.; Miley, H.S.; Panisko, M.E.; Savard, R.M.

    1994-07-01

    A computer code has been written at the Pacific Northwest Laboratory (PNL) to synthesize the results of typical gamma-ray spectroscopy experiments. The code, dubbed SYNTH, allows a use r to specify physical characteristics of a gamma-ray source, the quantity of the nuclides producing the radiation, the source-to-detector distance and the type and thickness of absorbers, the size and composition of the detector (Ge or NaI), and the electronic set up used to gather the data. In the process of specifying the parameters needed to synthesize a spectrum, several interesting intermediate results are produced, including a photopeak transmission function vs energy, a detector efficiency curve, and a weighted list of gamma and x rays produced from a set of nuclides. All of these intermediate results are available for graphical inspection and for printing. SYNTH runs on personal computers. It is menu driven and can be customized to user specifications. SYNTH contains robust support for coaxial germanium detectors and some support for sodium iodide detectors. SYNTH is not a finished product. A number of additional developments are planned. However, the existing code has been compared carefully to spectra obtained from National Institute for Standards and Technology (NIST) certified standards with very favorable results. Examples of the use of SYNTH and several spectral results will be presented

  7. SYNTH: A spectrum synthesizer

    International Nuclear Information System (INIS)

    Hensley, W.K.; McKinnon, A.D.; Miley, H.S.; Panisko, M.E.; Savard, R.M.

    1993-10-01

    A computer code has been written at the Pacific Northwest Laboratory (PNL) to synthesize the results of typical gamma ray spectroscopy experiments. The code, dubbed SYNTH, allows a user to specify physical characteristics of a gamma ray source, the quantity of the nuclides producing the radiation, the source-to-detector distance and the presence of absorbers, the type and size of the detector, and the electronic set up used to gather the data. In the process of specifying the parameters needed to synthesize a spectrum, several interesting intermediate results are produced, including a photopeak transmission function versus energy, a detector efficiency curve, and a weighted list of gamma and x rays produced from a set of nuclides. All of these intermediate results are available for graphical inspection and for printing. SYNTH runs on personal computers. It is menu driven and can be customized to user specifications. SYNTH contains robust support for coaxial germanium detectors and some support for sodium iodide detectors. SYNTH is not a finished product. A number of additional developments are planned. However, the existing code has been compared carefully to spectra obtained from National Institute for Standards and Technology (NIST) certified standards with very favorable results. Examples of the use of SYNTH and several spectral results are presented

  8. Characterization of ceramic powder compacts

    International Nuclear Information System (INIS)

    Yanai, K.; Ishimoto, S.; Kubo, T.; Ito, K.; Ishikawa, T.; Hayashi, H.

    1995-01-01

    UO 2 and Al 2 O 3 powder packing structures in cylindrical powder compacts are observed by scanning electron microscopy using polished cross sections of compacts fixed by low viscosity epoxy resin. Hard aggregates which are not destroyed during powder compaction are observed in some of the UO 2 powder compacts. A technique to measure local density in powder compacts is developed based on counting characteristic X-ray intensity by energy dispersive X-ray analysis (EDX). The local density of the corner portion of the powder compact fabricated by double-acting dry press is higher than that of the inner portion. ((orig.))

  9. Morphologic and structural characterization of the CoFe2O4 synthesized by combustion reaction

    International Nuclear Information System (INIS)

    Lima, M.S.; Sousa, J.-P.L.M.L.; Vieira, D.A.; Lira, H.L.; Costa, A.C.F.M.; Sasaki, J.M.

    2009-01-01

    CoFe 2 O 4 powders were synthesized by combustion reaction using glycine as fuel, aiming obtaining nanosized and monophase powders. Thus, different conditions of external heating during the synthesis were investigated. The powders were prepared according to the propellants and explosives theory, using glycine as fuel in the stoichiometric proportion (Φe = 1). During the synthesis the flame temperature and time were measured. The resulting powders were characterized by X-rays diffraction and scanning electronic microscopy (SEM). The results show that the condition in which the synthesis was realized it influences in the combustion flame temperature and time and contributes for the obtainment of powders with majority phase without secondary phases. Crystallite size varied of 33 to 50 nm. All powders presented morphology constituted by soft agglomerated formed by nanoparticles. (author). (author)

  10. Magnetically responsive enzyme powders

    Czech Academy of Sciences Publication Activity Database

    Pospišková, K.; Šafařík, Ivo

    2015-01-01

    Roč. 380, APR 2015 (2015), s. 197-200 ISSN 0304-8853 R&D Projects: GA MŠk(CZ) LD13021 Institutional support: RVO:67179843 Keywords : enzyme powders * cross-linking * magnetic modification * magnetic separation * magnetic iron oxides particles * microwave-assisted synthesis Subject RIV: CE - Biochemistry Impact factor: 2.357, year: 2015

  11. Powder neutron diffractometers

    International Nuclear Information System (INIS)

    Adib, M.

    2002-01-01

    Basic properties and applications of powder neutron Diffractometers are described for optimum use of the continuous neutron beams. These instruments are equipped with position sensitive detectors, neutron guide tubes, and both high intensity and high resolution modes of operation are possible .The principles of both direct and Fourier reverse time-of-flight neutron Diffractometers are also given

  12. Low Temperature Powder Coating

    Science.gov (United States)

    2011-02-09

    of volatile organic compounds (VOCs) and hazardous air pollutants (HAPs) • Legacy primers contain hexavalent chrome • Conventional powder coatings...coatings both in laboratory and field service evaluations • LTCPC allows environmental cost reductions through VOC/HAP elimination and hexavalent ... chrome reduction. • The LTCPC process greatly shortens the coating operation (LTCPC cures much more rapidly then conventional wet coatings) resulting in

  13. Laser cladding with powder

    NARCIS (Netherlands)

    Schneider, M.F.; Schneider, Marcel Fredrik

    1998-01-01

    This thesis is directed to laser cladding with powder and a CO2 laser as heat source. The laser beam intensity profile turned out to be an important pa6 Summary rameter in laser cladding. A numerical model was developed that allows the prediction of the surface temperature distribution that is

  14. Zinc Oxide Nano crystals Synthesized by Quenching Technique

    International Nuclear Information System (INIS)

    Norhayati Abu Bakar; Akrajas Ali Umar; Muhamad Mat Salleh; Muhammad Yahya

    2011-01-01

    This paper reports an attempt to synthesize non toxic zinc oxide (ZnO) nano crystals using a simple quenching technique. The hot zinc oxide powder was quenched in hexane solution to obtain ZnO nano crystals. As the result, diameter size of the synthesized ZnO is 200 nm. It was also exhibited a good crystalline with wurtzite phase. The nano crystals properties of ZnO were revealed from good absorbance and green luminescence under UV exposure. This may be related with oxygen vacancy ionization during the annealing process. (author)

  15. Synthesis method for ultrananocrystalline diamond in powder employing a coaxial arc plasma gun

    Science.gov (United States)

    Naragino, Hiroshi; Tominaga, Aki; Hanada, Kenji; Yoshitake, Tsuyoshi

    2015-07-01

    A new method that enables us to synthesize ultrananocrystalline diamond (UNCD) in powder is proposed. Highly energetic carbon species ejected from a graphite cathode of a coaxial arc plasma gun were provided on a quartz plate at a high density by repeated arc discharge in a compact vacuum chamber, and resultant films automatically peeled from the plate were aggregated and powdered. The grain size was easily controlled from 2.4 to 15.0 nm by changing the arc discharge energy. It was experimentally demonstrated that the proposed method is a new and promising method that enables us to synthesize UNCD in powder easily and controllably.

  16. Synthesis method for ultrananocrystalline diamond in powder employing a coaxial arc plasma gun

    International Nuclear Information System (INIS)

    Naragino, Hiroshi; Tominaga, Aki; Yoshitake, Tsuyoshi; Hanada, Kenji

    2015-01-01

    A new method that enables us to synthesize ultrananocrystalline diamond (UNCD) in powder is proposed. Highly energetic carbon species ejected from a graphite cathode of a coaxial arc plasma gun were provided on a quartz plate at a high density by repeated arc discharge in a compact vacuum chamber, and resultant films automatically peeled from the plate were aggregated and powdered. The grain size was easily controlled from 2.4 to 15.0 nm by changing the arc discharge energy. It was experimentally demonstrated that the proposed method is a new and promising method that enables us to synthesize UNCD in powder easily and controllably. (author)

  17. Piezoelectric Materials Synthesized by the Hydrothermal Method and Their Applications

    Directory of Open Access Journals (Sweden)

    Takeshi Morita

    2010-12-01

    Full Text Available Synthesis by the hydrothermal method has various advantages, including low reaction temperature, three-dimensional substrate availability, and automatic polarization alignment during the process. In this review, powder synthesis, the fabrication of piezoelectric thin films, and their applications are introduced. A polycrystalline lead zirconate titanate (PZT thin film was applied to a micro ultrasonic motor, and an epitaxial lead titanate (PbTiO3 thin film was estimated as a ferroelectric data storage medium. Ferroelectric and piezoelectric properties were successfully obtained for epitaxial PbTiO3 films. As lead-free piezoelectric powders, KNbO3 and NaNbO3 powders were synthesized by the hydrothermal method and sintered together to form (K,NaNbO3 ceramics, from which reasonable piezoelectric performance was achieved.

  18. Structure of the enzymatically synthesized fructan inulin

    International Nuclear Information System (INIS)

    Heyer, A.G.; Schroeer, B.; Radosta, S.; Wolff, D.; Czapla, S.; Springer, J.

    1998-01-01

    Construction, purification and characterization of a fusion protein of maltose-binding protein of Escherichia coli and the fructosyltransferase of Streptococcus mutans is described. With the purified protein, in vitro synthesis of inulin was performed. The obtained polysaccharide was characterized by high-performance size-exclusion chromatography (HPSEC) and static light scattering (SLS) in dilute aqueous and dimethyl sulfoxide solution. For all samples very high molecular weights between 60x10 6 and 90x10 6 g/mol and a remarkable small polydispersity index of 1.1 have been determined. Small root-mean-square radii of gyration point to a compact conformation in dilute solution. No difference between native and enzymatically synthesized inulin was observed by X-ray powder diffraction and thermoanalysis of solid samples. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  19. Structure of the enzymatically synthesized fructan inulin

    Energy Technology Data Exchange (ETDEWEB)

    Heyer, A.G.; Schroeer, B. [Max-Planck-Institut fuer Molekulare Pflanzenphysiologie, Karl-Liebknecht-Str. 25, 14476 Golm (Germany); Radosta, S. [Fraunhofer-Institut fuer Angewandte Polymerforschung, Postfach 126, 14504 Teltow (Germany); Wolff, D.; Czapla, S.; Springer, J. [Technische Universitaet Berlin, FG Makromolekulare Chemie, Str. des 17. Juni 135, 10623 Berlin (Germany)

    1998-12-15

    Construction, purification and characterization of a fusion protein of maltose-binding protein of Escherichia coli and the fructosyltransferase of Streptococcus mutans is described. With the purified protein, in vitro synthesis of inulin was performed. The obtained polysaccharide was characterized by high-performance size-exclusion chromatography (HPSEC) and static light scattering (SLS) in dilute aqueous and dimethyl sulfoxide solution. For all samples very high molecular weights between 60x10{sup 6} and 90x10{sup 6} g/mol and a remarkable small polydispersity index of 1.1 have been determined. Small root-mean-square radii of gyration point to a compact conformation in dilute solution. No difference between native and enzymatically synthesized inulin was observed by X-ray powder diffraction and thermoanalysis of solid samples. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  20. Method to blend separator powders

    Science.gov (United States)

    Guidotti, Ronald A.; Andazola, Arthur H.; Reinhardt, Frederick W.

    2007-12-04

    A method for making a blended powder mixture, whereby two or more powders are mixed in a container with a liquid selected from nitrogen or short-chain alcohols, where at least one of the powders has an angle of repose greater than approximately 50 degrees. The method is useful in preparing blended powders of Li halides and MgO for use in the preparation of thermal battery separators.

  1. Nanocrystalline AL2 O2 powders produced by laser induced gas phase reactions

    International Nuclear Information System (INIS)

    Borsella, E.; Botti, S.; Martelli, S.; Zappa, G.; Giorgi, R.; Turt, S.

    1993-01-01

    Nanocrystalline Al 2 O 3 powders were successfully synthesized by a CO 2 laser-driven gas-phase reaction involving trimethylaluminium (Al(CH 3 ) 3 ) and nitrous-oxide (N 2 O). Ethylene (C 2 H 4 ) was added as gas sensitizer. The as-synthesized powder particles showed a considerable carbon contamination and an amorphous-like structure. After thermal treatment at 1200-1400 degrees C, the powder was transformed to hexagonal a-Al 2 O 3 with very low carbon contamination as confirmed by X-ray diffraction, X-ray photo-electron spectroscopy and chemical analysis. The calcinated powders resulted to be spherical single crystal nanoparticles with a mean size of 15-20 nm, as determined by X-ray diffraction, electron microscopy and B.E.T. specific surface measurements. The laser synthesized Al 2 O 3 particles are well suited dispersoids for intermetallic alloy technology

  2. Plasma technology for powder particles

    Energy Technology Data Exchange (ETDEWEB)

    Kranz, E. (Technische Hochschule, Ilmenau (German Democratic Republic))

    1983-03-01

    A survey is given of principles and applications of plasma spraying and of powder transformation and generation in plasma considering spheroidization, grain size transformation, powder particle formation, powder reduction, and melting within the power range of 10/sup 3/ to 10/sup 7/ W. The products are applied in many industrial fields such as nuclear engineering, hard metal production, metallurgy, catalysis, and semiconductor techniques.

  3. Synthesis of Amorphous Powders of Ni-Si and Co-Si Alloys by Mechanical Alloying

    Science.gov (United States)

    Omuro, Keisuke; Miura, Harumatsu

    1991-05-01

    Amorphous powders of the Ni-Si and Co-Si alloys are synthesized by mechanical alloying (MA) from crystalline elemental powders using a high energy ball mill. The alloying and amorphization process is examined by X-ray diffraction, differential scanning calorimetry (DSC), and scanning electron microscopy. For the Ni-Si alloy, it is confirmed that the crystallization temperature of the MA powder, measured by DSC, is in good agreement with that of the powder sample prepared by mechanical grinding from the cast alloy ingot products of the same composition.

  4. Biocompatibility and antimicrobial activity of zinc(II doped hydroxyapatite, synthesized by hydrothermal method

    Directory of Open Access Journals (Sweden)

    Kojić Vesna

    2012-01-01

    Full Text Available In order to obtain multifunctional materials with good biocompatibility and antimicrobial effect, hydroxyapatite (HAp doped with Zn2+ was synthesized by hydrothermal method. Powders with different content of zinc ions were synthesized and compared with undoped HAp to investigation of Zn2+ ion influence on the antimicrobial activity of HAp. Analyses of undoped and Zn2+-doped powders before and after thermal treatment at 1200ºC were performed by SEM and XRD. Antimicrobial effects of powders were examined in relation to Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans in liquid medium. The results showed that the obtained powders have good antimicrobial activity, but higher antimicrobial activities of powders doped with Zn2+ were observed after annealing at 1200°C. For powders annealed at 1200°C in vitro biocompatibility tests MTT and DET with MRC-5 fibroblast cells in liquid medium were carried out. Based on MTT and DET tests it was shown that powders do not have a significant cytotoxic effect, which was confirmed by SEM analysis of MRC-5 fibroblast cells after theirs in vitro contact with powders. [Projekat Ministarstva nauke Republike Srbije, br. III 45019 and FP7-REGPOT-2009-1 NANOTECH FTM

  5. Synthesis of Uranium nitride powders using metal uranium powders

    International Nuclear Information System (INIS)

    Yang, Jae Ho; Kim, Dong Joo; Oh, Jang Soo; Rhee, Young Woo; Kim, Jong Hun; Kim, Keon Sik

    2012-01-01

    Uranium nitride (UN) is a potential fuel material for advanced nuclear reactors because of their high fuel density, high thermal conductivity, high melting temperature, and considerable breeding capability in LWRs. Uranium nitride powders can be fabricated by a carbothermic reduction of the oxide powders, or the nitriding of metal uranium. The carbothermic reduction has an advantage in the production of fine powders. However it has many drawbacks such as an inevitable engagement of impurities, process burden, and difficulties in reusing of expensive N 15 gas. Manufacturing concerns issued in the carbothermic reduction process can be solved by changing the starting materials from oxide powder to metals. However, in nitriding process of metal, it is difficult to obtain fine nitride powders because metal uranium is usually fabricated in the form of bulk ingots. In this study, a simple reaction method was tested to fabricate uranium nitride powders directly from uranium metal powders. We fabricated uranium metal spherical powder and flake using a centrifugal atomization method. The nitride powders were obtained by thermal treating those metal particles under nitrogen containing gas. We investigated the phase and morphology evolutions of powders during the nitriding process. A phase analysis of nitride powders was also a part of the present work

  6. Dispersing powders in liquids

    CERN Document Server

    Nelson, RD

    1988-01-01

    This book provides powder technologists with laboratory procedures for selecting dispersing agents and preparing stable dispersions that can then be used in particle size characterization instruments. Its broader goal is to introduce industrial chemists and engineers to the phenomena, terminology, physical principles, and chemical considerations involved in preparing and handling dispersions on a commercial scale. The book introduces novices to: - industrial problems due to improper degree of dispersion; - the nomenclature used in describing particles; - the basic physica

  7. Container for nuclear fuel powders

    International Nuclear Information System (INIS)

    Etheredge, B.F.; Larson, R.I.

    1982-01-01

    A critically safe container is disclosed for the storage and rapid discharge of enriched nuclear fuel material in powder form is disclosed. The container has a hollow, slab-shaped container body that has one critically safe dimension. A powder inlet is provided on one side wall of the body adjacent to a corner thereof and a powder discharge port is provided at another corner of the body approximately diagonal the powder inlet. Gas plenum for moving the powder during discharge are located along the side walls of the container adjacent the discharge port

  8. Fabrication of spherical high-nitrogen stainless steel powder alloys by mechanical alloying and thermal plasma spheroidization

    Science.gov (United States)

    Razumov, Nikolay G.; Wang, Qing Sheng; Popovich, Anatoly A.; Shamshurin, Aleksey I.

    2018-04-01

    This paper describes the results of experimental studies on the treatment of Fe-23Cr-11Mn-1N high-nitrogen stainless steel powder alloys, synthesized by the mechanical alloying (MA) of elemental powders in the flow of a radio frequency thermal plasma. The as-milled powder with irregular particles were successfully converted into spherical high-nitrogen stainless steel powder alloy. Measurement of the residual nitrogen content in the obtained powder, shown that during the plasma spheroidization process, part of the nitrogen escapes from the alloy.

  9. Preparation of superconductor precursor powders

    Science.gov (United States)

    Bhattacharya, Raghunath

    1998-01-01

    A process for the preparation of a precursor metallic powder composition for use in the subsequent formation of a superconductor. The process comprises the steps of providing an electrodeposition bath comprising an electrolyte medium and a cathode substrate electrode, and providing to the bath one or more soluble salts of one or more respective metals which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic and/or reduced particles formed at the electrode to drop as a powder from the electrode into the bath, and this powder, which is a precursor powder for superconductor production, is recovered from the bath for subsequent treatment. The process permits direct inclusion of all metals in the preparation of the precursor powder, and yields an amorphous product mixed on an atomic scale to thereby impart inherent high reactivity. Superconductors which can be formed from the precursor powder include pellet and powder-in-tube products.

  10. Sol-gel auto-combustion synthesis and properties of Co2Z-type hexagonal ferrite ultrafine powders

    Science.gov (United States)

    Liu, Junliang; Yang, Min; Wang, Shengyun; Lv, Jingqing; Li, Yuqing; Zhang, Ming

    2018-05-01

    Z-type hexagonal ferrite ultrafine powders with chemical formulations of (BaxSr1-x)3Co2Fe24O41 (x varied from 0.0 to 1.0) have been synthesized by a sol-gel auto-combustion technique. The average particle sizes of the synthesized powders ranged from 2 to 5 μm. The partial substitution of Ba2+ by Sr2+ led to the shrinkage of the crystal lattices and resulted in changes in the magnetic sub-lattices, which tailored the static and dynamic magnetic properties of the as-synthesized powders. As the substitution ratio of Ba2+ by Sr2+, the saturation magnetization of the synthesized powders almost consistently increased from 43.3 to 56.1 emu/g, while the real part of permeability approached to a relatively high value about 2.2 owing to the balance of the saturation magnetization and magnetic anisotropy field.

  11. MECHANICAL ALLOYING SYNTHESIS OF FORSTERITE-DIOPSIDE NANOCOMPOSITE POWDER FOR USING IN TISSUE ENGINEERING

    Directory of Open Access Journals (Sweden)

    Sorour Sadeghzade

    2015-03-01

    Full Text Available In present study the pure forsterite-diopside nanocomposite powder was successfully synthesized by the economical method of mechanical alloying and subsequence sintering, for the first time. The starting economical materials were talc (Mg3Si4H2O12, magnesium carbonate (MgCO3 and calcium carbonate (CaCO3 powders. The prepared powder was characterized by thermo gravimetric analysis (TGA, X-ray diffraction (XRD, and scanning electron microscopy (SEM. The results showed preparation of forsterite- diopside nanocomposite powder after 10 h mechanical alloying and sintering at 1200oC for 1 h. The powder crystallite sizes and agglomerated particle sizes were measured about 73 +/- 4 nm and 0.3 - 4 μm, respectively. Absence of enstatite that causes a reduction in mechanical and bioactivity properties of forsterite ceramic, is an important feature of produced powder.

  12. Synthesis of ultrafine alumina powders using egg white as complexing medium

    International Nuclear Information System (INIS)

    Salem, R.E.P.; Guilherme, K. A.; Chinelatto, A.S.A.; Chinelatto, A.L.

    2011-01-01

    Synthesis of alumina powders through chemical methods has been attracting much attention of researchers in the past few years, due to the ability to produce powders in nanometric scale with high degree of purity. In this work, there were synthesized alumina powders through a chemical route, using egg white as a complexing medium and aluminium nitrate as the source of Al 3+ cations. Egg white contains ovalbumin, a protein which acts effectively on the isolation of aluminium cations during the mixing process, enabling the formation of ultrafine alumina powders in a relatively economic and environmentally friendly way. The powders obtained by calcinations of the precursor resin were characterized by X-ray diffraction, specific surface area measurements, infrared spectroscopy and scanning electron microscopy. It was observed that the egg white, present at the reaction medium, allowed obtaining transition alumina powders, with high degree of purity. (author)

  13. Examination of Zinc Oxide Nanoparticles as a Fluorescent Fingerprint Detection Powder

    International Nuclear Information System (INIS)

    Tun Tun Lin

    2010-12-01

    Detection of latent fingerprint was performed using zinc oxide nanoparticles which were produced by simple and efficient method in aqueous media from zinc nitrate. Synthesized ZnO nanoparticles were characterized by XRD, SEM and AFM for ZnO purification and particle size examination. In this paper an effort has been made to compare the results of using ZnO nanoparticles and conventional fingerprint powders such as ZnO bulk powder, CaO, TiO2, printer toner powder and graphite. Fingerprints on different materials were also examined by the use of ZnO and Graphite powder, which is currently used in the Central Intelligence Department of Myanmar Police Force.From this research, it was observed that zinc oxide nanoparticles powder produced a much clearer picture of the fingerprints, compared to conventional powders and it has very good quality at sticking to the fingerprint residue but not to the background surface.

  14. Diffraction. Powder, amorphous, liquid

    International Nuclear Information System (INIS)

    Sosnowska, I.M.

    1999-01-01

    Neutron powder diffraction is a unique tool to observe all possible diffraction effects appearing in crystal. High-resolution neutron diffractometers have to be used in this study. Analysis of the magnetic structure of polycrystalline materials requires the use of high-resolution neutron diffraction in the range of large interplanar distances. As distinguished from the double axis diffractometers (DAS), which show high resolution only at small interplanar distances, TOF (time-of-flight) diffractometry offers the best resolution at large interplanar distances. (K.A.)

  15. LARC powder prepreg system

    Science.gov (United States)

    Baucom, Robert M.; Marchello, Joseph M.

    1990-01-01

    Thermoplastic prepregs of LARC-TPI have been produced in a fluidized bed unit on spread continuous fiber tows. The powders are melted on the fibers by radiant heating to adhere the polymer to the fiber. This process produces tow prepreg uniformly without imposing severe stress on the fibers or requiring long high temperature residence times for the polymer. Unit design theory and operating correlations have been developed to provide the basis for scale up to commercial operation. Special features of the operation are the pneumatic tow spreader, fluidized bed and resin feed systems.

  16. Hydrothermal synthesis of Pb(Zr0⋅52Ti0⋅48)O3 powders at low ...

    Indian Academy of Sciences (India)

    Administrator

    mental parameters, including Pb/(Zr, Ti) ratio, alkaline concentration, reaction temperature and time on the product powders were studied in detail. Pure PZT powders were synthesized at suitable experimental condi- tions and Raman spectra confirmed the PZT with a perovskite-type structure. The homogeneous PZT pow-.

  17. Mechanochemically synthesized Al2O3-TiC nanocomposite

    International Nuclear Information System (INIS)

    Mohammad Sharifi, E.; Karimzadeh, F.; Enayati, M.H.

    2010-01-01

    Al 2 O 3 -TiC nanocomposite was synthesized by ball milling of aluminum, titanium oxide and graphite powder mixtures. Effect of the milling time and heat treatment temperatures were investigated. The structural evolution of powder particles after different milling times was studied by X-ray diffractometry and scanning electron microscopy. The results showed that after 40 h of ball milling the Al/TiO 2 /C reacted with a self-propagating combustion mode producing Al 2 O 3 -TiC nanocomposite. In final stage of milling, alumina and titanium carbide crystallite sizes were less than 10 nm. After annealing at 900 o C for 1 h, Al 2 O 3 and TiC crystallite sizes remained constant, however increasing annealing temperature to 1200 o C increased Al 2 O 3 and TiC crystallite size to 65 and 30 nm, respectively. No phase change was observed after annealing of the synthesized Al 2 O 3 -TiC powder.

  18. Double Step Sintering Behavior Of 316L Nanoparticle Dispersed Micro-Sphere Powder

    Directory of Open Access Journals (Sweden)

    Jeon Byoungjun

    2015-06-01

    Full Text Available 316L stainless steel is a well-established engineering material and lots of components are fabricated by either ingot metallurgy or powder metallurgy. From the viewpoints of material properties and process versatility, powder metallurgy has been widely applied in industries. Generally, stainless steel powders are prepared by atomization processes and powder characteristics, compaction ability, and sinterability are quite different according to the powder preparation process. In the present study, a nanoparticle dispersed micro-sphere powder is synthesized by pulse wire explosion of 316L stainless steel wire in order to facilitate compaction ability and sintering ability. Nanoparticles which are deposited on the surface of micro-powder are advantageous for a rigid die compaction while spherical micro-powder is not to be compacted. Additionally, double step sintering behavior is observed for the powder in the dilatometry of cylindrical compact body. Earlier shrinkage peak comes from the sintering of nanoparticle and later one results from the micro-powder sintering. Microstructure as well as phase composition of the sintered body is investigated.

  19. Characterization of prealloyed copper powders treated in high energy ball mill

    International Nuclear Information System (INIS)

    Rajkovic, Viseslava; Bozic, Dusan; Jovanovic, Milan T.

    2006-01-01

    The inert gas atomised prealloyed copper powders containing 3.5 wt.% Al were milled up to 20 h in the planetary ball mill in order to oxidize aluminium in situ with oxygen from the air. In the next procedure compacts from milled powder were synthesized by hot-pressing in argon atmosphere. Compacts from as-received Cu-3.5 wt.% Al powder and electrolytic copper powder were also prepared under the same conditions. Microstructural and morphological changes of high energy milled powder as well as changes of thermal stability and electrical conductivity of compacts were studied as a function of milling time and high temperature exposure at 800 deg. C. Optical, scanning electron microscopy (SEM) and X-ray diffraction analysis were performed for microstructural characterization, whereas thermal stability and electrical conductivity were evaluated by microhardness measurements and conductometer Sigmatest, respectively. The prealloyed 5 h-milled and compacted powder showed a significant increase in microhardness reaching the value of 2600 MPa, about 4 times greater than that of compacts synthesized from as-received electrolytic copper powder (670 MPa). The electrical conductivity of compacts from 5 h-milled powder was 52% IACS. The results were discussed in terms of the effect of small grain size and finely distributed alumina dispersoids on hardening and thermal stability of compacts

  20. Characterization of Ni ferrites powders prepared by plasma arc discharge process

    Energy Technology Data Exchange (ETDEWEB)

    Safari, A. [Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University, Ahvaz (Iran, Islamic Republic of); Gheisari, Kh., E-mail: khgheisari@scu.ac.ir [Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University, Ahvaz (Iran, Islamic Republic of); Farbod, M. [Physics Department, Shahid Chamran University, Ahvaz (Iran, Islamic Republic of)

    2017-01-01

    The aim of this work was to synthesize a single-phase spinel structure from a mixture of zinc, iron and nickel powders by plasma arc discharge method. A mixture of zinc, iron and nickel powders with the appropriate molar ratio was prepared and formed into a cylindrical shape. The synthesis process was performed in air, oxygen and argon atmospheres with the applied arc current of 400 A and pressure of 1 atm. After establishing an arc between the electrodes, the produced powders were collected and their structure and magnetic properties were examined by XRD and VSM, respectively. ZnO as an impurity was appeared in the as-produced powders owing to the high reactivity of zinc atoms, preventing the formation of Ni–Zn ferrite. A pure spinel structure with the highest saturation magnetization (43.8 emu/g) was observed as zinc powders removed completely from the initial mixture. Morphological evaluations using field emission scanning electron microscopy showed that the mean size of fabricated nanoparticles was in the range 100–200 nm and was dependent on the production conditions. - Highlights: • Nanocrystalline Ni ferrite powders are prepared by plasma arc discharge process. • The mean particle size of the as-synthesized ceramic powders is about 100 nm. • The highest saturation magnetization is observed as zinc powders removed completely from the initial mixture.

  1. Effect of the microstructural morphology on UO{sub 2} powders

    Energy Technology Data Exchange (ETDEWEB)

    Ziouane, Y.; Lalleman, S.; Leturcq, G. [CEA, Centre de Marcoule, Nuclear Energy Division, RadioChemistry and Processes Department, SERA, LED, F-30207 Bagnols sur Ceze (France); Arab-Chapelet, B. [CEA, Centre de Marcoule, Nuclear Energy Division, RadioChemistry and Processes Department, SERA, LCAR, F-30207 Bagnols sur Ceze (France)

    2016-07-01

    Several UO{sub 2} powders with different morphologies were synthesized and characterized. Three different morphologies were synthesized thanks to sol-gel process (big heap of about 200 μm wide consisting of sintered crystallites) on the one hand, and to oxalic precipitations (one square platelet morphology and one hexagonal stick morphology) on the other hand. Significant differences in dissolution kinetics were observed. Therefore, the morphology of the powders was found to be a key parameter that has to be considered in the studies of UO{sub 2} dissolution kinetics. The second part of the study consists in dissolving in nitric acid in in the same operating conditions three UO{sub 2} powders having different crystallites sizes. It was shown that dissolution kinetics is dependent on the morphology at the micrometer scale but also on the powder oxygen stoichiometry. (authors)

  2. Nuclear fuel powder transfer device

    International Nuclear Information System (INIS)

    Komono, Akira

    1998-01-01

    A pair of parallel rails are laid between a receiving portion to a molding portion of a nuclear fuel powder transfer device. The rails are disposed to the upper portion of a plurality of parallel support columns at the same height. A powder container is disposed while being tilted in the inside of the vessel main body of a transfer device, and rotational shafts equipped with wheels are secured to right and left external walls. A nuclear powder to be mixed, together with additives, is supplied to the powder container of the transfer device. The transfer device engaged with the rails on the receiving side is transferred toward the molding portion. The wheels are rotated along the rails, and the rotational shafts, the vessel main body and the powder container are rotated. The nuclear powder in the tilted powder container disposed is rotated right and left and up and down by the rotation, and the powder is mixed satisfactory when it reaches the molding portion. (I.N.)

  3. Superconductors by powder metallurgy techniques

    International Nuclear Information System (INIS)

    Pickus, M.R.; Wang, J.L.F.

    1976-05-01

    Fabrication methods for Nb 3 Sn type compounds are described. Information is included on the Bell Telephone process, the General Electric tape process, superconductor stability, the bronze process, powder metallurgy multifilamentary tapes and wires, and current assessment of powder metallurgy superconducting wire

  4. Synthesis of nanocrystalline magnesium nitride (Mg3N2) powder using thermal plasma

    International Nuclear Information System (INIS)

    Kim, Dong-Wook; Kim, Tae-Hee; Park, Hyun-Woo; Park, Dong-Wha

    2011-01-01

    Nanocrystalline magnesium nitride (Mg 3 N 2 ) powder was synthesized from bulk magnesium by thermal plasma at atmospheric pressure. Magnesium vapor was generated through heating the bulk magnesium by DC plasma jet and reacted with ammonia gas. Injecting position and flow rates of ammonia gas were controlled to investigate an ideal condition for Mg 3 N 2 synthesis. The synthesized Mg 3 N 2 was cooled and collected on the chamber wall. Characteristics of the synthesized powders for each experimental condition were analyzed by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and thermogravity analysis (TGA). In absence of NH 3 , magnesium metal powder was formed. The synthesis with NH 3 injection in low temperature region resulted in a formation of crystalline magnesium nitride with trigonal morphology, whereas the mixture of magnesium metal and amorphous Mg 3 N 2 was formed when NH 3 was injected in high temperature region. Also, vaporization process of magnesium was discussed.

  5. Effect of Pressing Parameters on the Structure of Porous Materials Based on Cobalt and Nickel Powders

    Science.gov (United States)

    Shustov, V. S.; Rubtsov, N. M.; Alymov, M. I.; Ankudinov, A. B.; Evstratov, E. V.; Zelensky, V. A.

    2018-03-01

    Porous materials with a bulk porosity of more than 68% were synthesized by powder metallurgy methods from a cobalt-nickel mixture. The effect of the ratio of nickel and cobalt powders used in the synthesis of this porous material (including cases when either nickel or cobalt alone was applied) and the conditions of their compaction on structural parameters, such as open and closed porosities and pose size, was established.

  6. Fully automated parallel oligonucleotide synthesizer

    Czech Academy of Sciences Publication Activity Database

    Lebl, M.; Burger, Ch.; Ellman, B.; Heiner, D.; Ibrahim, G.; Jones, A.; Nibbe, M.; Thompson, J.; Mudra, Petr; Pokorný, Vít; Poncar, Pavel; Ženíšek, Karel

    2001-01-01

    Roč. 66, č. 8 (2001), s. 1299-1314 ISSN 0010-0765 Institutional research plan: CEZ:AV0Z4055905 Keywords : automated oligonucleotide synthesizer Subject RIV: CC - Organic Chemistry Impact factor: 0.778, year: 2001

  7. Luminescent characteristics of praseodymium-doped zinc aluminate powders

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Perez, C.D.; Garcia-Hipolito, M.; Alvarez-Fregoso, O. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Coyoacan, DF (Mexico); Alvarez-Perez, M.A. [Facultad de Odontologia, Universidad Nacional Autonoma de Mexico, Coyoacan, DF (Mexico); Ramos-Brito, F. [Laboratorio de Materiales Optoelectronicos, DIDe, Centro de Ciencias de Sinaloa, Av. De las Americas No. 2771 Nte. Col. Villa Universidad, Culiacan, Sinaloa (Mexico); Falcony, C. [Centro de Investigaciones y Estudios Avanzados del IPN, Departamento de Fisica, Mexico, DF (Mexico)

    2010-02-15

    In this research, we report the cathodoluminescence (CL) and preliminary photoluminescence (PL) properties of praseodymium-doped zinc aluminate powders. ZnAl{sub 2}O{sub 4}:Pr powders were synthesized by a very simple chemical process. X-ray diffraction spectra indicated a cubic spinel crystalline structure with an average crystallite size of 15 nm. CL properties of the powders were studied as a function of the praseodymium concentration and electron-accelerating potential. In this case, all the cathodoluminescent emission spectra showed main peaks located at 494, 535, 611, 646, and 733 nm, which were associated to the electronic transitions {sup 3}P{sub 0}{yields}{sup 3}H{sub 4}, {sup 3}P{sub 0}{yields}{sup 3}H{sub 5}, {sup 3}P{sub 0}{yields}{sup 3}H{sub 6}, {sup 3}P{sub 0}{yields}{sup 3}F{sub 2}, and {sup 3}P{sub 0}{yields}{sup 3}F{sub 4} of the Pr{sup 3+} ions, respectively. A quenching of the CL, with increasing doping concentration, was observed. Also, an increment on cathodoluminescent emission intensity was observed as the accelerating voltage increased. The PL emission spectrum showed similar characteristics to those of the CL spectra. The chemical composition of the powders, as determined by energy dispersive spectroscopy, is also reported. In addition, the surface morphology characteristics of the powders are shown. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  8. Light extinction in metallic powder beds: Correlation with powder structure

    International Nuclear Information System (INIS)

    Rombouts, M.; Froyen, L.; Gusarov, A.V.; Bentefour, E.H.; Glorieux, C.

    2005-01-01

    A theoretical correlation between the effective extinction coefficient, the specific surface area, and the chord length distribution of powder beds is verified experimentally. The investigated powder beds consist of metallic particles of several tens of microns. The effective extinction coefficients are measured by a light-transmission technique at a wavelength of 540 nm. The powder structure is characterized by a quantitative image analysis of powder bed cross sections resulting in two-point correlation functions and chord length distributions. The specific surface area of the powders is estimated by laser-diffraction particle-size analysis and by the two-point correlation function. The theoretically predicted tendency of increasing extinction coefficient with specific surface area per unit void volume is confirmed by the experiments. However, a significant quantitative discrepancy is found for several powders. No clear correlation of the extinction coefficient with the powder material and particle size, and morphology is revealed, which is in line with the assumption of geometrical optics

  9. Gas-Phase Combustion Synthesis of Aluminum Nitride Powder

    Science.gov (United States)

    Axelbaum, R. L.; Lottes, C. R.; Huertas, J. I.; Rosen, L. J.

    1996-01-01

    Due to its combined properties of high electrical resistivity and high thermal conductivity aluminum nitride (AlN) is a highly desirable material for electronics applications. Methods are being sought for synthesis of unagglomerated, nanometer-sized powders of this material, prepared in such a way that they can be consolidated into solid compacts having minimal oxygen content. A procedure for synthesizing these powders through gas-phase combustion is described. This novel approach involves reacting AlCl3, NH3, and Na vapors. Equilibrium thermodynamic calculations show that 100% yields can be obtained for these reactants with the products being AlN, NaCl, and H2. The NaCl by-product is used to coat the AlN particles in situ. The coating allows for control of AlN agglomeration and protects the powders from hydrolysis during post-flame handling. On the basis of thermodynamic and kinetic considerations, two different approaches were employed to produce the powder, in co-flow diffusion flame configurations. In the first approach, the three reactants were supplied in separate streams. In the second, the AlCl3 and NH3 were premixed with HCl and then reacted with Na vapor. X-ray diffraction (XRD) spectra of as-produced powders show only NaCl for the first case and NaCl and AlN for the second. After annealing at 775 C tinder dynamic vacuum, the salt was removed and XRD spectra of powders from both approaches show only AlN. Aluminum metal was also produced in the co-flow flame by reacting AlCl3 with Na. XRD spectra of as-produced powders show the products to be only NaCl and elemental aluminum.

  10. Characteristics of ceramic oxide nanoparticles synthesized using radio frequency produced thermal plasma

    International Nuclear Information System (INIS)

    Dhamale, Gayatri D.; Mathe, V.L.; Bhoraskar, S.V.; Ghorui, S.

    2015-01-01

    Thermal plasma devices with their unique processing capabilities due to extremely high temperature and steep temperature gradient play an important role in synthesis of ultrafine powders in the range of 100nm or less. High temperature gas phase synthesis in Radio Frequency (RF) thermal plasma reactor is an attractive route for mass production of refractory nanoparticles, especially in the case of rare earth oxides. Here we report synthesis of Yttrium Oxide (Y_2O_3), Neodymium Oxide (Nd_2O_3) and Aluminum Oxide (Al_2O_3) in an inductively coupled radio frequency thermal plasma reactor. Synthesized nanoparticles find wide application in various fields like gate dielectrics, photocatalytic applications, laser devices and photonics. Nano sized Yttrium oxide, Neodymium Oxide and Aluminum oxide powders were separately synthesized in an RF plasma reactor starting with micron sized irregular shaped precursor powders. The system was operated at 3MHz in atmospheric pressure at different power levels. Synthesized powders were scrapped out from different deposition locations inside the reactor and characterized for their phase, morphology, particle size, crystallinity and other characteristic features. Highly crystalline nature of the synthesized particles, narrow size distribution, location dependent phase formation, and distinct variation in the inherent defect states compared to the bulk are some of the important characteristic features observed

  11. Photoluminescence and hydrogen gas-sensing properties of titanium dioxide nanostructures synthesized by hydrothermal treatments

    CSIR Research Space (South Africa)

    Sikhwivhilu, LM

    2012-03-01

    Full Text Available Titanium dioxide (TiO2) nanostructures were synthesized by microwave-assisted and conventionally heated hydrothermal treatment of TiO2 powder. The tubular structures were converted to a rodlike shape by sintering the samples at various temperatures...

  12. Synthesis of a TiBw/Ti6Al4V composite by powder compact extrusion using a blended powder mixture

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Huiyang, E-mail: hl209@waikato.ac.nz [Waikato Center for Advanced Materials, School of Engineering, University of Waikato, Hamilton (New Zealand); Zhang, Deliang, E-mail: zhangdeliang@sjtu.edu.cn [State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai (China); Gabbitas, Brian, E-mail: briang@waikato.ac.nz [Waikato Center for Advanced Materials, School of Engineering, University of Waikato, Hamilton (New Zealand); Yang, Fei, E-mail: fyang@waikato.ac.nz [Waikato Center for Advanced Materials, School of Engineering, University of Waikato, Hamilton (New Zealand); Matthews, Steven, E-mail: S.Matthews@massey.ac.nz [School of Engineering and Advanced Technology, Massey University, Auckland (New Zealand)

    2014-09-01

    Highlights: • TiB/Ti6Al4V composites were prepared from extruded BE powders. • Different starting powders affected the morphologies of TiB whiskers formed in-situ. • A TiB/Ti6Al4V composite with TiB whiskers had good strength and ductility. • The strength and ductility achieved were superior to those obtained by other methods. - Abstract: A Ti–6 wt%Al–4 wt%V alloy (Ti6Al4V) matrix composite, reinforced by in situ synthesized TiB whiskers (TiBw) has been successfully fabricated by powder compact extrusion using a blended powder mixture. The microstructural characterization of the various extruded samples showed that the different starting powders, pre-alloyed powder plus boron powder or titanium plus Al–40V master alloy powder plus boron powder, had a significant effect on the morphology of the in situ synthesized TiB whiskers. It is also evident that the TiB whiskers affect the microstructural evolution of the Ti6Al4V matrix. The tensile test results indicated that the composite with a dispersion of fine TiB whiskers with high aspect ratios exhibited a high ultimate tensile stress (UTS) and yield stress (YS) of 1436 MPa and 1361 MPa, respectively, a reasonably good tensile ductility reflected by an elongation to fracture of 5.6% was also achieved. This is a significant improvement compared with as-extruded monolithic Ti6Al4V alloy produced in this study.

  13. Synthesis of a TiBw/Ti6Al4V composite by powder compact extrusion using a blended powder mixture

    International Nuclear Information System (INIS)

    Lu, Huiyang; Zhang, Deliang; Gabbitas, Brian; Yang, Fei; Matthews, Steven

    2014-01-01

    Highlights: • TiB/Ti6Al4V composites were prepared from extruded BE powders. • Different starting powders affected the morphologies of TiB whiskers formed in-situ. • A TiB/Ti6Al4V composite with TiB whiskers had good strength and ductility. • The strength and ductility achieved were superior to those obtained by other methods. - Abstract: A Ti–6 wt%Al–4 wt%V alloy (Ti6Al4V) matrix composite, reinforced by in situ synthesized TiB whiskers (TiBw) has been successfully fabricated by powder compact extrusion using a blended powder mixture. The microstructural characterization of the various extruded samples showed that the different starting powders, pre-alloyed powder plus boron powder or titanium plus Al–40V master alloy powder plus boron powder, had a significant effect on the morphology of the in situ synthesized TiB whiskers. It is also evident that the TiB whiskers affect the microstructural evolution of the Ti6Al4V matrix. The tensile test results indicated that the composite with a dispersion of fine TiB whiskers with high aspect ratios exhibited a high ultimate tensile stress (UTS) and yield stress (YS) of 1436 MPa and 1361 MPa, respectively, a reasonably good tensile ductility reflected by an elongation to fracture of 5.6% was also achieved. This is a significant improvement compared with as-extruded monolithic Ti6Al4V alloy produced in this study

  14. Application of laser in powder metallurgy

    International Nuclear Information System (INIS)

    Tolochko, N.K.

    1995-01-01

    Modern status of works in the field of laser application in powder metallurgy (powders preparation, sintering, coatings formation, powder materials processing) is considered. The attention is paid to the new promising direction in powder products shape-formation technology - laser layer-by-layer selective powders sintering and bulk sintering of packaged layered profiles produced by laser cutting of powder-based sheet blanks. 67 refs

  15. Black powder in gas pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Sherik, Abdelmounam [Saudi Aramco, Dhahran (Saudi Arabia)

    2009-07-01

    Despite its common occurrence in the gas industry, black powder is a problem that is not well understood across the industry, in terms of its chemical and physical properties, source, formation, prevention or management of its impacts. In order to prevent or effectively manage the impacts of black powder, it is essential to have knowledge of its chemical and physical properties, formation mechanisms and sources. The present paper is divided into three parts. The first part of this paper is a synopsis of published literature. The second part reviews the recent laboratory and field work conducted at Saudi Aramco Research and Development Center to determine the compositions, properties, sources and formation mechanisms of black powder in gas transmission systems. Microhardness, nano-indentation, X-ray Diffraction (XRD), X-ray Fluorescence (XRF) and Scanning Electron Microscopy (SEM) techniques were used to analyze a large number of black powder samples collected from the field. Our findings showed that black powder is generated inside pipelines due to internal corrosion and that the composition of black powder is dependent on the composition of transported gas. The final part presents a summary and brief discussion of various black powder management methods. (author)

  16. Fabrication of high-alloy powders consisting of spherical particles from ultradispersed components

    Science.gov (United States)

    Samokhin, A. V.; Fadeev, A. A.; Sinayskiy, M. A.; Alekseev, N. V.; Tsvetkov, Yu. V.; Arzhatkina, O. A.

    2017-07-01

    It is shown that powders of a model high alloy consisting of spherical particles 25-50 μm in size can be synthesized from a starting ultradispersed powder, which is made of a mixture of the alloy components and is fabricated by the magnesiothermal reduction of metal chlorides in the potassium chloride melt. The synthesis includes the stages of microgranulation of an ultradispersed powder, heat treatment of microgranules, classification of the microgranules with the separation of microgranule fraction of 25-50 μm, spheroidization of the separated fraction in a thermal plasma flow, and classification with the separation of a fraction of micro- and submicrometer-sized particles.

  17. Nonvolatile RRAM cells from polymeric composites embedding recycled SiC powders.

    Science.gov (United States)

    De Girolamo Del Mauro, Anna; Nenna, Giuseppe; Miscioscia, Riccardo; Freda, Cesare; Portofino, Sabrina; Galvagno, Sergio; Minarini, Carla

    2014-10-21

    Silicon carbide powders have been synthesized from tires utilizing a patented recycling process. Dynamic light scattering, Raman spectroscopy, SEM microscopy, and X-ray diffraction have been carried out to gather knowledge about powders and the final composite structure. The obtained powder has been proven to induce resistive switching in a PMMA polymer-based composite device. Memory effect has been detected in two-terminal devices having coplanar contacts and quantified by read-write-erase measurements in terms of level separation and persistence.

  18. (TECTONA GRANDIS LEAF POWDER

    Directory of Open Access Journals (Sweden)

    Yash Mishra

    2015-01-01

    Full Text Available In this study, the adsorption potential of Teak (Tectona grandis leaf powder (TLP toremove Methylene blue (MB and Malachite Green (MG dye molecules from aqueoussolution was investigated. Batch experiments were conducted to evaluate the influenceof operational parameters such as, pH (2−9, adsorbent dosage (1−7 g/L, contact time(15−150 minutes and initial dye concentration (20−120 mg/L at stirring speed of 150rpm for the adsorption of MB and MG on TLP. Maximum removal efficiency of 98.4%and 95.1% was achieved for MB and MG dye, respectively. The experimentalequilibrium data were analysed using Langmuir, Freundlich and Temkin isothermmodels and it was found that, it fitted well to the Freundlich isotherm model. Thesurface structure and morphology of the adsorbent was characterized using scanningelectron microscopy (SEM and the presence of functional groups and its interactionwith the dye molecules were analysed using Fourier transform infrared spectroscopy(FTIR. Based on the investigation, it has been demonstrated that the teak leaf powderhas good potential for effective adsorption of methylene blue and malachite green dye.

  19. Low pressure powder injection moulding of stainless steel powders

    Energy Technology Data Exchange (ETDEWEB)

    Zampieron, J.V.; Soares, J.P.; Mathias, F.; Rossi, J.L. [Powder Processing Center CCP, Inst. de Pesquisas Energeticas e Nucleares, Sao Paulo, SP (Brazil); Filho, F.A. [IPEN, Inst. de Pesquisas Energeticas e Nucleares, Cidade Univ., Sao Paulo, SP (Brazil)

    2001-07-01

    Low-pressure powder injection moulding was used to obtain AISI 316L stainless steel parts. A rheological study was undertaken using gas-atomised powders and binders. The binders used were based on carnauba wax, paraffin, low density polyethylene and microcrystalline wax. The metal powders were characterised in terms of morphology, particle size distribution and specific surface area. These results were correlated to the rheological behaviour. The mixture was injected in the shape of square bar specimens to evaluate the performance of the injection process in the green state, and after sintering. The parameters such as injection pressure, viscosity and temperature were analysed for process optimisation. The binders were thermally removed in low vacuum with the assistance of alumina powders. Debinding and sintering were performed in a single step. This procedure shortened considerably the debinding and sintering time. (orig.)

  20. Shock compaction of molybdenum powder

    Science.gov (United States)

    Ahrens, T. J.; Kostka, D.; Vreeland, T., Jr.; Schwarz, R. B.; Kasiraj, P.

    1983-01-01

    Shock recovery experiments which were carried out in the 9 to 12 GPa range on 1.4 distension Mo and appear adequate to compact to full density ( 45 (SIGMA)m) powders were examined. The stress levels, however, are below those calculated to be from 100 to approx. 22 GPa which a frictional heating model predicts are required to consolidate approx. 10 to 50 (SIGMA)m particles. The model predicts that powders that have a distension of m=1.6 shock pressures of 14 to 72 GPa are required to consolidate Mo powders in the 50 to 10 (SIGMA)m range.

  1. Characterization of tin selenides synthesized by high-energy milling

    Directory of Open Access Journals (Sweden)

    Marcela Achimovičová

    2011-12-01

    Full Text Available Tin selenides SnSeX (x=1,2 were synthesized from tin and selenium powder precursors by high-energy milling in the planetary ballmill Pulverisette 6 (Fritsch, Germany. The orthorhombic tin selenide SnSe and the hexagonal tin diselenide SnSe2 phases were formed after4 min and 5 min of milling, respectively. Specific surface area of both selenides increased with increasing time of mechanochemicalsynthesis. The particle size distribution analysis demonstrated that the synthesized products contain agglomerated selenide particlesconsisting of numerous idiomorphic tin selenide crystals, measuring from 2 to more than 100 nm in diameter, which were also documentedby TEM. UV-Vis spectrophotometry confirmed that tin selenide particles do not behave as quantum dots.

  2. The Mossbauer spectra of carbon nanotubes synthesize using ferrite catalyst

    International Nuclear Information System (INIS)

    Zhang Haiyan; Lin Jiapeng; Peng Zuxiong; Zeng Guoxun; Pang Jinshan; Chen Yiming

    2009-01-01

    The ferrite powder with honeycombed structure obtained by chemical combustion was used as catalyst to synthesize multi-walled carbon nanotubes by chemical vapor deposition. The magnetic components and characters of the the carbon nanotubes synthesized were investigated by X-ray diffraction (XRD), Mossbauer spectra and vibrating-sample magnetometer (VSM). The ferric components of the carbon nanotubes samples can be identified by Mossbauer spectra. The Mossbauer spectra of carbon nanotubes sample after purification contains two ferromagnetic sextet components corresponding to α-Fe species and Fe 3 C (cementite) species. While the Mossbauer spectra of the carbon nanotubes sample before purification contains three ferromagnetic sextet components corresponding to α-Fe species, Fe 3 C species and γ-Fe 2 O 3 . The saturation magnetization intensity Ms of carbon nanotubes sample after purification is decreased from 46.61 to 2.94 emu/g, but the coercive force increasd and reached 328Oe.

  3. Ultrasonic wave propagation in powders

    Science.gov (United States)

    Al-Lashi, R. S.; Povey, M. J. W.; Watson, N. J.

    2018-05-01

    Powder clumps (cakes) has a significant effect on the flowability and stability of powders. Powder caking is mainly caused by moisture migration due to wetting and environmental (temperature and humidity) changes. The process of moisture migration caking involves creating liquid bridges between the particles during condensation which subsequently harden to form solid bridges. Therefore, an effective and reliable technique is required to quantitatively and non-invasively monitor caking kinetics and effective stiffness. This paper describes two ultrasonic instruments (ultrasonic velocity pulse and airborne ultrasound systems) that have been used to monitor the caking phenomenon. Also, it discusses the relationship between the ultrasonic velocity and attenuation measurements and tracking caking kinetics and the effective stiffness of powders.

  4. Neutron Powder Diffraction in Sweden

    International Nuclear Information System (INIS)

    Tellgren, R.

    1986-01-01

    Neutron powder diffraction in Sweden has developed around the research reactor R2 in Studsvik. The article describes this facility and presents a historical review of research results obtained. It also gives some ideas of plans for future development

  5. Powder metallurgy - some economic considerations

    Energy Technology Data Exchange (ETDEWEB)

    Kassem, M.E.

    1982-01-01

    As a forming process powder metallurgy offers reductions in material and energy consumption. The engineering prerequisites and economics are discussed in relation to several industrial applications including automobile parts. 14 refs.

  6. Powder metallurgy of refractory metals

    International Nuclear Information System (INIS)

    Eck, R.

    1979-01-01

    This paper reports on the powder metallurgical methods for the production of high-melting materials, such as pure metals and their alloys, compound materials with a tungsten base and hard metals from liquid phase sintered carbides. (author)

  7. Structure and soft magnetic properties of the bulk samples prepared by compaction of the mixtures of Co-based and Fe-based powders

    International Nuclear Information System (INIS)

    Fuezer, J.; Bednarcik, J.; Kollar, P.; Roth, S.

    2007-01-01

    Ball milling of CoFeZrB ribbons and subsequent compaction of the resulting powders were used to prepare bulk amorphous samples. Further, two sets of powder samples were prepared by cryomilling of FeCuNbMoSiB alloy in amorphous and nanocrystalline state. Amorphous and nanocrystalline FeCuNbMoSiB powders were blended with CoFeZrB powder at different concentrations. Such powder mixtures were consolidated and several bulk nanocomposites have been synthesized. An addition of nanocrystalline or amorphous FeCuNbMoSiB powder to amorphous CoFeZrB powder caused a decrease of the magnetostriction of the resultant bulk samples, while the coercivity shows an opposite behavior. Our results show that the powder consolidation by hot pressing is an alternative method for the preparation of bulk metallic glasses, which are difficult to prepare by casting methods

  8. Dry and coating of powders

    International Nuclear Information System (INIS)

    Alonso, M.; Alguacil, F. J.

    1999-01-01

    This paper presents a review on the mixing and coating of powders by dry processes. The reviews surveys fundamental works on mixture characterization (mixing index definitions and sampling techniques), mixing mechanisms and models, segregation with especial emphasis on free-surface segregation, mixing of cohesive powders and interparticle forces, ordered mixing (dry coating) including mechanism, model and applications and mixing equipment selection. (Author) 180 refs

  9. Pressurized Anneal of Consolidated Powders

    Science.gov (United States)

    Nemir, David Charles (Inventor); Rubio, Edward S. (Inventor); Beck, Jan Bastian (Inventor)

    2017-01-01

    Systems and methods for producing a dense, well bonded solid material from a powder may include consolidating the powder utilizing any suitable consolidation method, such as explosive shockwave consolidation. The systems and methods may also include a post-processing thermal treatment that exploits a mismatch between the coefficients of thermal expansion between the consolidated material and the container. Due to the mismatch in the coefficients, internal pressure on the consolidated material during the heat treatment may be increased.

  10. Evaluation of Biological Activities of Chemically Synthesized Silver Nanoparticles

    International Nuclear Information System (INIS)

    Mostafa, A. A.; Solkamy, E.N.; Sayed, Sh. R. M.; Khan, M.; Shaik, M.R.; Al-Warthan, A.; Adil, S.F.

    2015-01-01

    Silver nanoparticles were synthesized by the earlier reported methods. The synthesized nanoparticles were characterized using ultraviolet-visible spectrophotometry (UV/Vis), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and X-ray powder diffraction (XRD). The synthesized materials were also evaluated for their antibacterial activity against Gram positive and Gram negative bacterial strains. TEM micrograph showed the spherical morphology of AgNPs with size range of 40-60 nm. The synthesized nanoparticles showed a strong antimicrobial activity and their effect depends upon bacterial strain as AgNPs exhibited greater inhibition zone for Pseudomonas aeruginosa (19.1 mm) followed by Staphylococcus aureus (14.8?mm) and S. pyogenes (13.6 mm) while the least activity was observed for Salmonella typhi (12.5 mm) at concentration of 5 μg/disc. The minimum inhibitory concentration (MIC) of AgNPs against S. aureus was 2.5 μg/disc and less than 2.5 μg/disc for P. aeruginosa. These results suggested that AgNPs can be used as an effective antiseptic agent for infectious control in medical field.

  11. Information Retrieval for Ecological Syntheses

    Science.gov (United States)

    Bayliss, Helen R.; Beyer, Fiona R.

    2015-01-01

    Research syntheses are increasingly being conducted within the fields of ecology and environmental management. Information retrieval is crucial in any synthesis in identifying data for inclusion whilst potentially reducing biases in the dataset gathered, yet the nature of ecological information provides several challenges when compared with…

  12. Method of synthesizing pyrite nanocrystals

    Science.gov (United States)

    Wadia, Cyrus; Wu, Yue

    2013-04-23

    A method of synthesizing pyrite nanocrystals is disclosed which in one embodiment includes forming a solution of iron (III) diethyl dithiophosphate and tetra-alkyl-ammonium halide in water. The solution is heated under pressure. Pyrite nanocrystal particles are then recovered from the solution.

  13. 21 CFR 73.1647 - Copper powder.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Copper powder. 73.1647 Section 73.1647 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1647 Copper powder. (a) Identity. (1) The color additive copper powder is a very fine free-flowing metallic powder prepared from virgin electrolytic copper. It...

  14. Aluminum powder size and microstructure effects on properties of boron nitride reinforced aluminum matrix composites fabricated by semi-solid powder metallurgy

    International Nuclear Information System (INIS)

    Chen, Cunguang; Guo, Leichen; Luo, Ji; Hao, Junjie; Guo, Zhimeng; Volinsky, Alex A.

    2015-01-01

    Al matrix composite reinforced by hexagonal boron nitride (h-BN) with nearly full densification was successfully fabricated by the semi-solid powder metallurgy technique. The h-BN/Al composites were synthesized with elemental pure Al powder size of d_5_0=35, 12 and 2 μm. The powder morphology and the structural characteristics of the composites were analyzed using X-ray diffraction, scanning and transmission electron microscopy. The density, Brinell hardness and compressive behavior of the samples were characterized. Density measurement of the Al composites revealed that the composite densification can be effectively promoted by plenty of embedded liquid phase under pressure. Composites prepared using Al powder with varying granularity showed different grain characteristics, and in situ recrystallization occurred inside the original grains with 35 μm Al powder. A sharp interface consisting of Al/Al_2O_3/h-BN was present in the composites. Both the compressive strength and the fracture strain of the investigated composites increased with the decrease of the Al powder size, along with the Brinell hardness. The composite with 2 μm Al powder exhibited the highest relative density (99.3%), Brinell harness (HB 128), compressive strength (763 MPa) and fracture strain (0.299).

  15. Some peculiarities of zirconium tungstate synthesis by thermal decomposition of hydrothermal precursors

    International Nuclear Information System (INIS)

    Gubanov, Alexander I.; Dedova, Elena S.; Plyusnin, Pavel E.; Filatov, Eugeny Y.; Kardash, Tatyana Y.; Korenev, Sergey V.; Kulkov, Sergey N.

    2014-01-01

    Highlights: • Synthesis of ZrW 2 O 8 using hydrothermal method. • On hydrothermal synthesis optimal conc. of HCl in the reaction mixture is 2.3 M. • Thermal decomposition of ZrW 2 O 7 ((OH) 1.5 ,Cl 0.5 )·2H 2 O begins are 200 °S. • Amorphous intermediate crystallizes into cubic single-phase ZrW 2 O 8 above 550 °S. • ZrW 2 O 8 destructed at temperatures above 700 °S. - Abstract: This article discusses some peculiarities of the synthesis of ZrW 2 O 8 (1) using thermal decomposition of the precursor ZrW 2 O 7 ((OH) 1.5 ,Cl 0.5 )·2H 2 O (2) prepared by hydrothermal method. On hydrothermal synthesis of 2 the optimal concentration of hydrochloric acid in the reaction mixture is about 2.3 M. TG approach to determine the chemical composition of the precursor was suggested. It has been found that the precursor for the synthesis of zirconium tungstate has chemical formula 2. Thermal decomposition of the precursor 2 begins at 200 °S and affords an amorphous intermediate, which crystallizes as a cubic phase 1 above 550 °S with an exoeffect. The temperature of the beginning of the transition from amorphous to the crystalline state is 350 ± 25 °S

  16. Facile synthesis and electrical switching properties of V{sub 2}O{sub 3} powders

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Haining; Liu, Dongqing, E-mail: dongqingliu@ymail.com; Cheng, Haifeng; Yang, Lixiang; Zhang, Chaoyang; Zheng, Wenwei

    2017-03-15

    Highlights: • Single crystal uniform V{sub 2}O{sub 3} powders have been synthesized without additional surfactant. • Powders were obtained in only 6 h. • Powders exhibit reversible phase transition properties. • Powders have excellent electrical switching properties with resistance changes as large as 10{sup 4}. - Abstract: V{sub 2}O{sub 3} powders were synthesized with mercaptoacetic acid (C{sub 2}H{sub 4}O{sub 2}S) as reducing agent and stabilizer via a facile hydrothermal approach. The crystalline structure, surface morphology, valence state of the derived V{sub 2}O{sub 3} powders were characterized via X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy. It was found that the ratio and reaction time played a duel role in the formation and morphology of the V{sub 2}O{sub 3} powders. The metal-insulator transition properties of V{sub 2}O{sub 3} powders were studied by the differential scanning calorimetry curve and variable temperature Raman spectra. The change in electrical resistance due to the metal-insulator transition was measured from 80 to 240 K using physical property measurement system. The results showed V{sub 2}O{sub 3} samples had excellent electrical switching properties with resistance changes as large as 10{sup 4}. This simple and fast synthesis approach makes the V{sub 2}O{sub 3} powders easily accessible for exploring their fundamental properties and potential applications in novel electronic devices.

  17. In situ synthesis of NiAl–NbB2 composite powder through combustion synthesis

    International Nuclear Information System (INIS)

    Shokati, Ali Akbar; Parvin, Nader; Sabzianpour, Naser; Shokati, Mohammad; Hemmati, Ali

    2013-01-01

    Highlights: ► A Novel NiAl matrix composite powder with 0–40 wt.% NbB 2 was synthesized. ► Composite powders were synthesized by thermal explosion reaction of Ni–Al–Nb–B system. ► Microhardness of NiAl considerably increased with raising NbB 2 content. ► Synthesized composite powders is a good candidate as precursor for thermal barrier application. - Abstract: Synthesis of a novel NiAl matrix composite powder reinforced with 0–40 wt.% NbB 2 by combustion synthesis in thermal explosion mode was investigated. The elemental powders of Ni, Al, Nb, and amorphous boron were used as starting material. For all compositions final products consisted of only the NiAl and NbB 2 phases. Coarser NbB 2 with a relatively uniform distribution in NiAl matrix was formed with rising NbB 2 content. Microhardness of NiAl considerably increased from 377 ± 13 HV 0.05 to 866 ± 81 HV 0.05 for NiAl with 40 wt.% NbB 2 . High microhardness, proper size and distribution of NbB 2 in NiAl matrix make it a good candidate as precursor for thermal spray application.

  18. Nanocrystals-based Macroporous Materials Synthesized by Freeze-drying Combustion

    International Nuclear Information System (INIS)

    Yan, Ruiqiang; Chen, Yu; Lin, Ye; Chen, Fanglin

    2016-01-01

    We present a novel freeze-drying combustion method for synthesis of macroporous powders with nano-network, using Sm 0.2 Ce 0.8 O 1.9 (SDC) as an example. The metal nitrate salt solution mixed with glycine is frozen to form homogeneous nitrate/glycine mixture and then freeze-dried through sublimation of ice crystals. Upon combustion of the freeze-dried mixture, SDC powders with macroporous microstructure consisting of 10–20 nm nanocrystals, high surface area and excellent sinterability are achieved. High resolution transmission electron microscopy (HRTEM) analysis indicates that nanodomains due to aggregation/segregation of dopants in the SDC powders obtained from freeze-drying combustion are much smaller than those in the SDC powders synthesized by the conventional nitrate solution combustion approach, demonstrating better elemental homogeneity and improved conductivity. Using low cost precursors and simple processing conditions, freeze-drying combustion can be a versatile method to synthesize nanocrystalline powders with excellent composition homogeneity for broad applications.

  19. Shock diffraction in alumina powder

    International Nuclear Information System (INIS)

    Venz, G.; Killen, P.D.; Page, N.W.

    1996-01-01

    In order to produce complex shaped components by dynamic compaction of ceramic powders detailed knowledge of their response under shock loading conditions is required. This work attempts to provide data on release effects and shock attenuation in 1 μm and 5 μm α-alumina powders which were compacted to between 85 % and 95 % of the solid phase density by the impact of high velocity steel projectiles. As in previous work, the powder was loaded into large cylindrical dies with horizontal marker layers of a contrasting coloured powder to provide a record of powder displacement in the recovered specimens. After recovery and infiltration with a thermosetting resin the specimens were sectioned and polished to reveal the structure formed by the passage of the projectile and shock wave. Results indicate that the shock pressures generated were of the order of 0.5 to 1.4 GPa and higher, with shock velocities and sound speeds in the ranges 650 to 800 m/s and 350 to 400 m/s respectively

  20. NANOCOMPOSITE POWDERS FOR NEW CONTACT MATERIALS BASED ONCOPPER AND ALUMINA

    Directory of Open Access Journals (Sweden)

    Marija Korać

    2008-11-01

    Full Text Available This paper is a contribution to characterization of Cu-Al2O3 powders with nanostructure designed for the production of dispersion strengthened contact materials. New materials with predetermined properties can be successfully synthesized by utilizing the principles of hydrometallurgy and powder metallurgy. The results show a development of a new procedure for the synthesis. The applied characterization methods were differential thermal and thermogravimetric analysis (DTA-TGA, X-ray diffraction (XRD, scanning electron microscopy (SEM, Transmission Electron Microscopy (TEM: Focused Ion Beam (FIB and Analytical Electron Microscopy (AEM. Nanostructure characteristics, particle size in range 20-50 nm, and uniform distribution of dispersoide in copper matrix were validated.

  1. Y-TZP ceramic processing from coprecipitated powders : A comparative study with three commercial dental ceramics

    NARCIS (Netherlands)

    Lazar, Dolores R. R.; Bottino, Marco C.; Ozcan, Mutlu; Valandro, Luiz Felipe; Amaral, Regina; Ussui, Valter; Bressiani, Ana H. A.

    2008-01-01

    Objectives. (1) To synthesize 3 mol% yttria-stabilized zirconia (3Y-TZP) powders via coprecipitation route, (2) to obtain zirconia ceramic specimens, analyze surface characteristics, and mechanical properties, and (3) to compare the processed material with three reinforced dental ceramics. Methods.

  2. Luminescence properties of YAG:Nd nano-sized ceramic powders ...

    Indian Academy of Sciences (India)

    Abstract. Nano-sized ceramic powders with weaker aggregation of Nd3+-doped yttrium aluminum garnet. (YAG:Nd3+) were synthesized via co-microemulsion and microwave heating. This method provides a limited small space in a micelle for the formation of nano-sized precursors. It also requires a very short heating time, ...

  3. Microwave hydrothermal synthesis and characterization of PZT 52/48 powders

    International Nuclear Information System (INIS)

    Teixeira, G.F.; Gasparotto, G.; Santos, N.A.; Zaghete, M.A.; Varela, J.A.; Longo, E.

    2009-01-01

    Full text: Lead Zirconate Titanate (PZT) is a ceramic witch has great interest because of their ferroelectric, piezoelectric, and other electrical properties. In this work Pb(ZrxTi1-x)O3 powders were synthesized by microwave hydrothermal synthesis (M-H) at 180°C without excess lead content. This method allows obtaining particles whit nanometer size, good stoichiometric controls, high purity and crystalline degree at low temperatures and short times of synthesis. Powders were synthesized with molar concentration of 0.15 mol.L -1 during different times: 30 min, 2, 4, 6 and 8 h. After that the powders were characterized by X-ray diffraction (XRD), Field Emission Gun (FEG) and photoluminescence (PL). Through analysis it is observed that the crystalline phase of PZT is obtained from 2 hours of synthesis and this same time also presents more intense PL emission. (author)

  4. Synthesis of Nickel and Nickel Hydroxide Nano powders by Simplified Chemical Reduction

    International Nuclear Information System (INIS)

    Tientong, J.; Garcia, S.; Thurber, C.R.; Golden, T.D.

    2014-01-01

    Nickel nano powders were synthesized by a chemical reduction of nickel ions with hydrazine hydrate at ph ∼ 12.5. Sonication of the solutions created a temperature of 54-65 °C to activate the reduction reaction of nickel nanoparticles. The solution ph affected the composition of the resulting nanoparticles. Nickel hydroxide nanoparticles were formed from an alkaline solution (ph ∼10) of nickel-hydrazine complexed by dropwise titration. X-ray diffraction of the powder and the analysis of the resulting Williamson-Hall plots revealed that the particle size of the powders ranged from 12 to 14 nm. Addition of polyvinylpyrrolidone into the synthesis decreased the nickel nanoparticle size to approximately 7 nm. Dynamic light scattering and scanning electron microscopy confirmed that the particles were in the nanometer range. The structure of the synthesized nickel and nickel hydroxide nanoparticles was identified by X-ray diffraction and Fourier transform infrared spectroscopy.

  5. Solid phase syntheses of oligoureas

    Energy Technology Data Exchange (ETDEWEB)

    Burgess, K.; Linthicum, D.S.; Russell, D.H.; Shin, H.; Shitangkoon, A.; Totani, R.; Zhang, A.J.; Ibarzo, J. [Texas A& M Univ., College Station, TX (United States)

    1997-02-19

    Isocyanates 7 were formed from monoprotected diamines 3 or 6, which in turn can be easily prepared from commercially available N-BOC- or N-FMOC-protected amino acid derivatives. Isocyanates 7, formed in situ, could be coupled directly to a solid support functionalized with amine groups or to amino acids anchored on resins using CH{sub 2}Cl{sub 2} as solvent and an 11 h coupling time at 25 {degree}C. Such couplings afforded peptidomimetics with an N-phthaloyl group at the N-terminus. The optimal conditions identified for removal of the N-phthaloyl group were to use 60% hydrazine in DMF for 1-3 h. Several sequences of amino acids coupled to ureas (`peptidic ureas`) and of sequential urea units (`oligoureas`) were prepared via solid phase syntheses and isolated by HPLC. Partition coefficients were measured for two of these peptidomimetics, and their water solubilities were found to be similar to the corresponding peptides. A small library of 160 analogues of the YGGFL-amide sequence was prepared via Houghten`s tea bag methodology. This library was tested for binding to the anti-{beta}-endorphin monoclonal antibody. Overall, this paper describes methodology for solid phase syntheses of oligourea derivatives with side chains corresponding to some of the protein amino acids. The chemistry involved is ideal for high-throughput syntheses and screening operations. 51 refs., 3 figs., 2 tabs.

  6. Method of solidifying powderous wastes

    International Nuclear Information System (INIS)

    Kakimoto, Akira; Miyake, Takashi; Sato, Shuichi; Inagaki, Yuzo.

    1985-01-01

    Purpose: To improve the properties of solidification products, in the case of solidifying powderous wastes with thermosetting resins. Method. A solvent for the solution of the thermosetting resin is admixed with the powderous wastes into a paste-like form prior to adding the resin to the wastes, which are then mixed with the resin solution. As the result, those solidification products having the specific gravity and the compression strength more excellent than those of the conventional ones, and much higher than the reference values can be obtained. (Kamimura, M.)

  7. Reverse martensitic transformation in alumina-15 vol% zirconia nanostructured powder synthesized by high energy ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Maneshian, M.H. [Department of Materials Science and Engineering, Sharif University of Technology, Azadi Avenue, P.O. Box 11365-9466, Tehran (Iran, Islamic Republic of)], E-mail: mh_maneshian@yahoo.com; Banerjee, M.K. [National Institute of Foundry and Forge Technology, Hatia, Ranchi 834003 (India)

    2008-07-14

    In the present work, three alumina-15 vol% zirconia composites with Y{sub 2}O{sub 3}, MgO as dopants and without oxide as dopant have been investigated. High energy ball milling (HEBM) provides the positive thermodynamic driving force for monoclinic to tetragonal transformation and it reduces starting temperature for the reverse martensitic transformation, meanwhile mobility of zirconium cations and oxygen anions are enhanced in zirconia by HEBM. The general, albeit heuristic, reasoning is corroborated by nanocrystallity, particle size and also the retained monoclinic seem to play an important role. After 10 h HEBM, approximately 28% zirconia tetragonal phase is achieved. Non-stoichiometric tetragonal zirconia phase; Zr{sub 0.95}O{sub 2} is seen to have been achieved by high energy ball milling (HEBM). The structural and compositional evolutions during HEBM have been investigated using X-ray diffraction method (XRD) and scanning electron microscopy (SEM). High resolution transmission electron microscope (TEM) is also used for further understanding about the phenomenological changes taking place during high energy ball milling.

  8. Mechanochemical synthesis of fluorescent carbon dots from cellulose powders

    Science.gov (United States)

    Chae, Ari; Ram Choi, Bo; Choi, Yujin; Jo, Seongho; Kang, Eun Bi; Lee, Hyukjin; Park, Sung Young; In, Insik

    2018-04-01

    A novel mechanochemical method was firstly developed to synthesize carbon nanodots (CNDs) or carbon nano-onions (CNOs) through high-pressure homogenization of cellulose powders as naturally abundant resource depending on the treatment times. While CNDs (less than 5 nm in size) showed spherical and amorphous morphology, CNOs (10-50 nm in size) presented polyhedral shape, and onion-like outer lattice structure, graphene-like interlattice spacing of 0.36 nm. CNOs showed blue emissions, moderate dispersibility in aqueous media, and high cell viability, which enables efficient fluorescence imaging of cellular media.

  9. Synthesis of Yttria-stabilized zirconia nanoparticles by decomposition of metal nitrates coated on carbon powder

    International Nuclear Information System (INIS)

    Jiang, S.; Stangle, G.C.; Amarakoon, V.R.; Schulze, W.A.

    1996-01-01

    Weakly agglomerated nanoparticles of yttria-stabilized zirconia (YSZ) were synthesized by a novel process which involved the decomposition of metal nitrates that had been coated on ultrafine carbon black powder, after which the carbon black was gasified. The use of ultrafine, high-surface-area carbon black powder apparently allowed the nanocrystalline oxide particles to form and remain separate from each other, after which the carbon black was gasified at a somewhat higher temperature. As a result, the degree of agglomeration was shown to be relatively low. The average crystallite size and the specific surface area of the as-synthesized YSZ nanoparticles were 5∼6 nm and 130 m 2 /g, respectively, for powder synthesized at 650 degree C. The as-synthesized YSZ nanoparticles had a light brown color and were translucent, which differs distinctly from conventional YSZ particles which are typically white and opaque. The mechanism of the synthesis process was investigated, and indicated that the gasification temperature had a direct effect on the crystallite size of the as-synthesized YSZ nanoparticles. High-density and ultrafine-grained YSZ ceramic articles were prepared by fast-firing, using a dwell temperature of 1250 degree C and a dwell time of two minutes or less. copyright 1996 Materials Research Society

  10. Direct Iron Coating onto Nd-Fe-B Powder by Thermal Decomposition of Iron Pentacarbonyl

    International Nuclear Information System (INIS)

    Yamamuro, S; Okano, M; Tanaka, T; Sumiyama, K; Nozawa, N; Nishiuchi, T; Hirosawa, S; Ohkubo, T

    2011-01-01

    Iron-coated Nd-Fe-B composite powder was prepared by thermal decomposition of iron pentacarbonyl in an inert organic solvent in the presence of alkylamine. Though this method is based on a modified solution-phase process to synthesize highly size-controlled iron nanoparticles, it is in turn featured by a suppressed formation of iron nanoparticles to achieve an efficient iron coating solely onto the surfaces of rare-earth magnet powder. The Nd-Fe-B magnetic powder was successfully coated by iron shells whose thicknesses were of the order of submicrometer to micrometer, being tuneable by the amount of initially loaded iron pentacarbonyl in a reaction flask. The amount of the coated iron reached to more than 10 wt.% of the initial Nd-Fe-B magnetic powder, which is practically sufficient to fabricate Nd-Fe-B/α-Fe nanocomposite permanent magnets.

  11. Sorption activity investigation of ultrafine powders of high temperature melting point compounds in atmospheric pressure conditions

    International Nuclear Information System (INIS)

    Rudneva, V.V.

    2006-01-01

    A study is made in saturation with gas in the air for ultradispersed chromium carbonitride and boride powders synthesized in a nitrogen plasma jet according to three variants: from elements, from oxides, from chromium trichloride. It is established that in the air on temperature increasing the powders adsorb considerable amounts of oxygen and water vapor. This results in surface oxidation of powder particles and a loss in specific combination of properties. Preliminary vacuum heat treatment is shown to decrease sharply the rate of atmospheric gas adsorption. The quantity of adsorbed gases is dependent on a carbon monoxide concentration in a particle surface layer and the availability of adsorption centers. The number of such centers in the layer can be controlled by vacuum heat treatment conditions. The interaction of the powders with atmospheric gases is concluded to be of adsorption-diffusion nature [ru

  12. Synthesis characterization and sintering of cobalt-doped lanthanum chromite powders for use in SOFCs

    International Nuclear Information System (INIS)

    Yamagata, Chieko; Mello-Castanho, Sonia R.H.

    2009-01-01

    Doped lanthanum chromite is a promising as interconnect material because of its good conductivity at high temperatures and its stability in oxidizing and reducing atmospheres. Perovskite oxide powders of Co-doped lanthanum chromite were synthesized by dispersing precursor metal salt solutions in a polymer matrix followed by a thermal treatment. XRD patterns showed that a highly crystalline cobalt-doped lanthanum chromite was obtained. Fine perovskite powder with a surface area of 6.15 m 2 g -1 calcined at 700 deg C for 1 h, were obtained. After the sample sintered at 1450 deg C for 3h, the powder reached high densities exceeding 97% of the theoretical density. The proposed here has proved to be a very promising technique for the synthesis of lanthanum chromite powders. (author)

  13. Enhancement of the electrochemical performance in LiFePO4 cathode materials synthesized by using the sol-gel method

    Directory of Open Access Journals (Sweden)

    Kyong-Soo Hong

    2010-11-01

    Full Text Available LiFePO4 powders were synthesized by using the sol-gel and the solid-state reaction methods. The chemical states of Fe ions were studied by using XPS, and their electrochemical properties according to the oxidation states of Fe ions were compared. The average oxidation state of Fe ions in LiFePO4 powders synthesized by using the solid-state reaction method was found to be Fe3+, on the other hand, that of Fe ions synthesized by using the sol-gel method was found to be Fe2+. The obtained discharge capacities were 50 mAh/g and 120 mAh/g at a rate 0.1 C in LiFePO4 synthesized by using the solid-state reaction and sol-gel methods, respectively. Relatively a good cycling stability was observed in sol-gel prepared powder.

  14. The analysis of powder diffraction data

    International Nuclear Information System (INIS)

    David, W.I.F.; Harrison, W.T.A.

    1986-01-01

    The paper reviews neutron powder diffraction data analysis, with emphasis on the structural aspects of powder diffraction and the future possibilities afforded by the latest generation of very high resolution neutron and x-ray powder diffractometers. Traditional x-ray powder diffraction techniques are outlined. Structural studies by powder diffraction are discussed with respect to the Rietveld method, and a case study in the Rietveld refinement method and developments of the Rietveld method are described. Finally studies using high resolution powder diffraction at the Spallation Neutron Source, ISIS at the Rutherford Appleton Laboratory are summarized. (U.K.)

  15. A new approach to synthesize supported ruthenium phosphides for hydrodesulfurization

    International Nuclear Information System (INIS)

    Wang, Qingfang; Wang, Zhiqiang; Yin, Xiaoqian; Zhou, Linxi; Zhang, Minghui

    2016-01-01

    Highlights: • We bring out a new method to synthesize noble metal phosphides at low temperature. • Both RuP and Ru_2P were synthesized using triphenylphosphine as phosphorus sources. • Ru_2P was the better active phase for HDS than RuP and metal Ru. • RuP/SiO_2 prepared by new method had better HDS activity to that by TPR method. - Abstract: Supported noble metal ruthenium phosphides were synthesized by one-step H_2-thermal treatment method using triphenylphosphine (TPP) as phosphorus sources at low temperatures. Two phosphides RuP and Ru_2P can be prepared by this method via varying the molar ratio of metal salt and TPP. The as-prepared phosphides were characterized by X-ray powder diffraction (XRD), low-temperature N_2 adsorption, CO chemisorption and transmission electronic microscopy (TEM). The supported ruthenium phosphides prepared by new method and conventional method together with contradistinctive metallic ruthenium were evaluated in hydrodesulfurization (HDS) of dibenzothiophene (DBT). The catalytic results showed that metal-rich Ru_2P was the better active phase for HDS than RuP and metal Ru. Besides this, ruthenium phosphide catalyst prepared by new method exhibited superior HDS activity to that prepared by conventional method.

  16. A new approach to synthesize supported ruthenium phosphides for hydrodesulfurization

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qingfang [Tianjin Key Laboratory of Water Environment and Resources, Tianjin Normal University, Tianjin 300387 (China); Key Laboratory of Advanced Energy Materials Chemistry (MOE), Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), College of Chemistry, Nankai University, Tianjin 300071 (China); Wang, Zhiqiang [Tianjin Key Laboratory of Water Environment and Resources, Tianjin Normal University, Tianjin 300387 (China); Yin, Xiaoqian; Zhou, Linxi [Key Laboratory of Advanced Energy Materials Chemistry (MOE), Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), College of Chemistry, Nankai University, Tianjin 300071 (China); Zhang, Minghui, E-mail: zhangmh@nankai.edu.cn [Key Laboratory of Advanced Energy Materials Chemistry (MOE), Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), College of Chemistry, Nankai University, Tianjin 300071 (China); College of Chemistry and Environmental Science, Kashgar University, Kashgar 844006 (China)

    2016-02-15

    Highlights: • We bring out a new method to synthesize noble metal phosphides at low temperature. • Both RuP and Ru{sub 2}P were synthesized using triphenylphosphine as phosphorus sources. • Ru{sub 2}P was the better active phase for HDS than RuP and metal Ru. • RuP/SiO{sub 2} prepared by new method had better HDS activity to that by TPR method. - Abstract: Supported noble metal ruthenium phosphides were synthesized by one-step H{sub 2}-thermal treatment method using triphenylphosphine (TPP) as phosphorus sources at low temperatures. Two phosphides RuP and Ru{sub 2}P can be prepared by this method via varying the molar ratio of metal salt and TPP. The as-prepared phosphides were characterized by X-ray powder diffraction (XRD), low-temperature N{sub 2} adsorption, CO chemisorption and transmission electronic microscopy (TEM). The supported ruthenium phosphides prepared by new method and conventional method together with contradistinctive metallic ruthenium were evaluated in hydrodesulfurization (HDS) of dibenzothiophene (DBT). The catalytic results showed that metal-rich Ru{sub 2}P was the better active phase for HDS than RuP and metal Ru. Besides this, ruthenium phosphide catalyst prepared by new method exhibited superior HDS activity to that prepared by conventional method.

  17. A novel nanostructure of cadmium oxide synthesized by mechanochemical method

    Energy Technology Data Exchange (ETDEWEB)

    Tadjarodi, A., E-mail: tajarodi@iust.ac.ir [Research Laboratory of Inorganic Materials Synthesis, Department of Chemistry, Iran University of Science and Technology, 16846-13114 Tehran (Iran, Islamic Republic of); Imani, M. [Research Laboratory of Inorganic Materials Synthesis, Department of Chemistry, Iran University of Science and Technology, 16846-13114 Tehran (Iran, Islamic Republic of)

    2011-11-15

    Highlights: {yields} A novel nanostructure of CdO was synthesized by mechanochemical reaction followed by calcination. {yields} Mechanochemical method is a simple and low-cost to synthesize nanomaterials. {yields} The obtained precursor was characterized by FT-IR, NMR techniques and elemental analysis. {yields} SEM images showed cauliflower-like shape of sample with components average diameter of 68 nm. {yields} The rods and tubes bundles with single crystalline nature were revealed by ED pattern and TEM images. -- Abstract: Cauliflower-like cadmium oxide (CdO) nanostructure was synthesized by mechanochemical reaction followed calcination procedure. Cadmium acetate dihydrate and acetamide were used as reagents and the resulting precursor was calcinated at 450 {sup o}C for 2 h in air. The structures of the precursor and resultant product of the heating treatment were characterized using Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and elemental analysis, X-ray powder diffraction (XRD), energy-dispersive X-ray spectroscopy analysis (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron diffraction pattern (ED). SEM and TEM images revealed the cauliflower-like morphology of the sample. This structure includes the bundles of rods and tubes in nanoscale, which combine with each other and form the resulting morphology with the average diameter, 68 nm of the components. ED pattern indicated the single crystal nature of the formed bundles.

  18. A novel nanostructure of cadmium oxide synthesized by mechanochemical method

    International Nuclear Information System (INIS)

    Tadjarodi, A.; Imani, M.

    2011-01-01

    Highlights: → A novel nanostructure of CdO was synthesized by mechanochemical reaction followed by calcination. → Mechanochemical method is a simple and low-cost to synthesize nanomaterials. → The obtained precursor was characterized by FT-IR, NMR techniques and elemental analysis. → SEM images showed cauliflower-like shape of sample with components average diameter of 68 nm. → The rods and tubes bundles with single crystalline nature were revealed by ED pattern and TEM images. -- Abstract: Cauliflower-like cadmium oxide (CdO) nanostructure was synthesized by mechanochemical reaction followed calcination procedure. Cadmium acetate dihydrate and acetamide were used as reagents and the resulting precursor was calcinated at 450 o C for 2 h in air. The structures of the precursor and resultant product of the heating treatment were characterized using Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and elemental analysis, X-ray powder diffraction (XRD), energy-dispersive X-ray spectroscopy analysis (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron diffraction pattern (ED). SEM and TEM images revealed the cauliflower-like morphology of the sample. This structure includes the bundles of rods and tubes in nanoscale, which combine with each other and form the resulting morphology with the average diameter, 68 nm of the components. ED pattern indicated the single crystal nature of the formed bundles.

  19. Metallography of powder metallurgy materials

    International Nuclear Information System (INIS)

    Lawley, Alan; Murphy, Thomas F.

    2003-01-01

    The primary distinction between the microstructure of an ingot metallurgy/wrought material and one fabricated by the powder metallurgy route of pressing followed by sintering is the presence of porosity in the latter. In its various morphologies, porosity affects the mechanical, physical, chemical, electrical and thermal properties of the material. Thus, it is important to be able to characterize quantitatively the microstructure of powder metallurgy parts and components. Metallographic procedures necessary for the reliable characterization of microstructures in powder metallurgy materials are reviewed, with emphasis on the intrinsic challenges presented by the presence of porosity. To illustrate the utility of these techniques, five case studies are presented involving powder metallurgy materials. These case studies demonstrate problem solving via metallography in diverse situations: failure of a tungsten carbide-coated precipitation hardening stainless steel, failure of a steel pump gear, quantification of the degree of sinter (DOS), simulation of performance of a porous filter using automated image analysis, and analysis of failure in a sinter brazed part assembly

  20. Electro/powder separation process

    International Nuclear Information System (INIS)

    Dunn, J.P.

    1977-01-01

    A report is presented to introduce the ELECTRO/POWDER process to the P/M Industry. The process effectively uses electrostatic forces to convey, sort, meter, and blend fine powders. The major advantages of this separating process consist of the processing of primary particles, low particle energy due to particle velocity control and the pattern of particle movement over the sieve (vertical oscillation of particles above the sieve aperture). The report briefly describes the forces involved in both mechanical and sieving devices, with major emphasis on the operating principles of this process. Sieve separation of particulates is basically the result of two physical separating processes which occur simultaneously or independently; separation (dispersion) of particulates from each other and the size separation by passage through fixed apertures. In order to accomplish this goal, mechanical sieving devices utilize various motions to induce shear forces between the sieve surface and the particulates, and between the particulates themselves. It is noted that the ELECTRO/POWDER process is making steady progress in becoming an industrial tool for sieving and feeding of fine particles. Its potential extends into both the blending and admixing of powders, either by incorporating two opposing feeders, one being charged with the opposite polarity or by modifying the ELECTRO/SIEVE to incorporate more than one input and a solid electrode to replace the sieve electrode

  1. Method of synthesizing tungsten nanoparticles

    Science.gov (United States)

    Thoma, Steven G; Anderson, Travis M

    2013-02-12

    A method to synthesize tungsten nanoparticles has been developed that enables synthesis of nanometer-scale, monodisperse particles that can be stabilized only by tetrahydrofuran. The method can be used at room temperature, is scalable, and the product concentrated by standard means. Since no additives or stabilizing surfactants are required, this method is particularly well suited for producing tungsten nanoparticles for dispersion in polymers. If complete dispersion is achieved due to the size of the nanoparticles, then the optical properties of the polymer can be largely maintained.

  2. Optical fusions and proportional syntheses

    Science.gov (United States)

    Albert-Vanel, Michel

    2002-06-01

    A tragic error is being made in the literature concerning matters of color when dealing with optical fusions. They are still considered to be of additive nature, whereas experience shows us somewhat different results. The goal of this presentation is to show that fusions are, in fact, of 'proportional' nature, tending to be additive or subtractive, depending on each individual case. Using the pointillist paintings done in the manner of Seurat, or the spinning discs experiment could highlight this intermediate sector of the proportional. So, let us try to examine more closely what occurs in fact, by reviewing additive, subtractive and proportional syntheses.

  3. Polymer quenched prealloyed metal powder

    Science.gov (United States)

    Hajaligol, Mohammad R.; Fleischhauer, Grier; German, Randall M.

    2001-01-01

    A powder metallurgical process of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1% B, .ltoreq.1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, and/or .ltoreq.3 % Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 .mu.m. Final stress relief annealing can be carried out in the B2 phase temperature range.

  4. THE INFLUENCE OF RECUPIRATION’S METHODS OF GRAPHITE TO PROPERTIES OF SYNTHESIZED DIAMONDS

    Directory of Open Access Journals (Sweden)

    G. P. Bogatyreva

    2015-03-01

    Full Text Available The graphite’s waste can be used for synthesis of diamonds. It is established, that activation of graphite’s waste essential influence on a degree of transition of graph-ite in diamond and their physico-chemical properties. The activation of th graphite’s waste changes essentially their absorption and structural characteristics and to a great extent affect the characteristics of synthesized diamond. Thermal activation of graphite’s waste leads to that are synthesized, basically, diamond micropowders, and electrochemical — diamond grinding powders.

  5. Green and red luminescence in co-precipitation synthesized Pr:LuAG nanophosphor

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, S. Arun; Kumar, K. Ashok; Gunaseelan, M.; Senthilselvan, J., E-mail: jsselvan@hotmail.com [Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai–600 025, Tamil Nadu (India); Asokan, K. [Materials Science Group, Inter University Accelerator Centre, New Delhi-110067 (India)

    2016-05-06

    Pr:LuAG nanophosphor is an effective candidate in magnetic resonance imaging coupled positron emission tomography (MRI-PET) for medical imaging and scintillator applications. LuAG:Pr (0.05, 0.15 mol%) nanoscale ceramic powders were synthesized by co-precipitation method using urea as precipitant. Effect of antisite defect on structure and luminescence behavior was investigated. Pr:LuAG nanoceramic powders are found crystallized in cubic structure by high temperature calcination at 1400 °C and it shows antisite defect. HR-SEM analysis revealed spherically shaped Pr:LuAG nanoceramic particulate powders with ∼100 nm size. By the excitation at 450 nm, Pr:LuAG nanophosphor exhibit green to red luminescence in the wavelength range of 520 to 680 nm, which is originated from multiplet transition of Pr{sup 3+} ions.

  6. Doped titanium dioxide nanocrystalline powders with high photocatalytic activity

    International Nuclear Information System (INIS)

    Castro, A.L.; Nunes, M.R.; Carvalho, M.D.; Ferreira, L.P.; Jumas, J.-C.; Costa, F.M.; Florencio, M.H.

    2009-01-01

    Doped titanium dioxide nanopowders (M:TiO 2 ; M=Fe, Co, Nb, Sb) with anatase structure were successfully synthesized through an hydrothermal route preceded by a precipitation doping step. Structural and morphological characterizations were performed by powder XRD and TEM. Thermodynamic stability studies allowed to conclude that the anatase structure is highly stable for all doped TiO 2 prepared compounds. The photocatalytic efficiency of the synthesized nanopowders was tested and the results showed an appreciable enhancement in the photoactivity of the Sb:TiO 2 and Nb:TiO 2 , whereas no photocatalytic activity was detected for the Fe:TiO 2 and Co:TiO 2 nanopowders. These results were correlated to the doping ions oxidation states, determined by Moessbauer spectroscopy and magnetization data. - Graphical abstract: Doped titanium dioxide nanopowders (M:TiO 2 ; M=Fe, Co, Nb, Sb) with highly stable anatase structure were successfully synthesized through an hydrothermal route. The photocatalytic efficiencies of the synthesized nanopowders were tested and the results show an appreciable enhancement in the photoactivity of the Sb:TiO 2 and Nb:TiO 2 .

  7. Plasma Synthesized Doped Boron Nanopowder for MgB2 Superconductors

    International Nuclear Information System (INIS)

    Marzik, James V.

    2012-01-01

    Under this program, a process to synthesize nano-sized doped boron powder by a plasma synthesis process was developed and scaled up from 20 gram batches at program start to over 200 grams by program end. Over 75 batches of boron nanopowder were made by RF plasma synthesis. Particle sizes were typically in the 20-200 nm range. The powder was synthesized by the reductive pyrolysis of BCl 3 in hydrogen in an RF plasma. A wide range of process parameters were investigated including plasma power, torch geometry, gas flow rates, and process pressure. The powder-in-tube technique was used to make monofilament and multifilament superconducting wires. MgB 2 wire made with Specialty Materials plasma synthesized boron nanopowder exhibited superconducting properties that significantly exceeded the program goals. Superconducting critical currents, J c , in excess of 10 5 A cm -2 at magnetic fields of 8 tesla were reproducibly achieved. The upper critical magnetic field in wires fabricated with program boron powder were H c2 (0) = 37 tesla, demonstrating the potential of these materials for high field magnet applications. T c in carbon-doped MgB 2 powder showed a systematic decrease with increasing carbon precursor gas flows, indicating the plasma synthesis process can give precise control over dopant concentrations. Synthesis rates increased by a factor of 400% over the course of the program, demonstrating the scalability of the powder synthesis process. The plasma synthesis equipment at Specialty Materials has successfully and reproducibly made high quality boron nanopowder for MgB 2 superconductors. Research and development from this program enabled Specialty Materials to successfully scale up the powder synthesis process by a factor of ten and to double the size of its powder pilot plant. Thus far the program has been a technical success. It is anticipated that continued systematic development of plasma processing parameters, dopant chemistry and concentration, wire

  8. Investigation of pressing of molybdenum powder compacts

    International Nuclear Information System (INIS)

    Mymrin, S.A.; Kuznetsov, V.Eh.; Yampol'skij, M.L.; Leonov, S.A.; Mikhridinov, R.M.; Korzukhin, V.A.

    1990-01-01

    Results of an experimental investigation into pressing of compacts of MCh type molybdenum powders using the industrial equipment are presented. To measure the density of powder molybdenum billets a radioisotopic density meter with cesium-137 is used as radioactive gamma radiation source. The dependence of the produced billet density on the specific compacting pressure at different values of the powder bulk density is ascertained

  9. MECHANICS OF DYNAMIC POWDER COMPACTION PROCESS

    OpenAIRE

    Nurettin YAVUZ

    1996-01-01

    In recent years, interest in dynamic compaction methods of metal powders has increased due to the need to improve compaction properties and to increase production rates of compacts. In this paper, review of dynamic and explosive compaction of metal powders are given. An attempt is made to get a better understanding of the compaction process with the mechanicis of powder compaction.

  10. 21 CFR 73.2645 - Aluminum powder.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Aluminum powder. 73.2645 Section 73.2645 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2645 Aluminum powder. (a) Identity and specifications. The color additive aluminum powder shall conform in identity and specifications to the requirements of...

  11. 21 CFR 73.1645 - Aluminum powder.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Aluminum powder. 73.1645 Section 73.1645 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1645 Aluminum powder. (a) Identity. (1) The color additive aluminum powder shall be composed of finely divided particles of aluminum prepared from virgin aluminum. It...

  12. 21 CFR 73.2647 - Copper powder.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Copper powder. 73.2647 Section 73.2647 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2647 Copper powder. (a) Identity and specifications. The color additive copper powder shall conform in identity and specifications to the requirements of § 73...

  13. Synthesis of nanostructured LiTi2(PO4)3 powder by a Pechini-type polymerizable complex method

    International Nuclear Information System (INIS)

    Mariappan, C.R.; Galven, C.; Crosnier-Lopez, M.-P.; Le Berre, F.; Bohnke, O.

    2006-01-01

    The nanostructured NASICON-type LiTi 2 (PO 4 ) 3 (LTP) material has been synthesized by Pechini-type polymerizable complex method. The use of water-soluble ammonium citratoperoxotitanate (IV) metal complex instead of alkoxides as precursor allows to prepare monophase material. Thermal analyses have been carried out on the powder precursor to check the weight loss and synthesis temperature. X-ray powder diffraction analysis (XRD) has been performed on the LTP powder obtained after heating the powder precursor over a temperature range from 550 to 1050 deg. C for 2 h. By varying the molar ratio of citric acid to metal ion (CA/Ti) and citric acid to ethylene glycol (CA/EG), the grain size of the LTP powder could be modified. The formation of small and well-crystalline grains, in the order of 50-125 nm in size, has been determined from the XRD patterns and confirmed by transmission electron microscopy

  14. Effect of heat absorbing powder addition on cell morphology of porous titanium composite manufactured by reactive precursor method

    International Nuclear Information System (INIS)

    Kobashi, Makoto; Kamiya, Yoshinori; Kanetake, Naoyuki

    2012-01-01

    Open-cell structured porous titanium/ceramics composite was synthesized by a reactive precursor method using titanium and boron carbide (B 4 C) as reactant powders. Pore morphology was controlled by adding heat absorbing powder (titanium diboride: TiB 2 ) in the Ti+B 4 C blended powder. The effects of molar blending ratio of titanium and B 4 C and the amount of heat absorbing powder addition on the cell morphology (either open or closed) were investigated. Fine and homogeneous open-cell structure was achieved by adding appropriate amount of heat absorbing agent powder (>15 vol%), and the relative density of the specimen after the reaction became closer to that of the precursor by increasing TiB 2 volume fraction. When the volume fraction of TiB 2 addition was 20%, the open-cell fraction was maintained as 1.0 regardless of the relative density of the precursor.

  15. In-Flight Formation of Nano-Crystalline Titanium Dioxide Powder in a Plasma Jet and Its Characterization

    International Nuclear Information System (INIS)

    Ananthapadmanabhan, P. V.; Thiyagarajan, T. K.; Sreekumar, K. P.; Vijay, M.; Selvarajan, V.; Yu, Jiaguo; Liu, Shengwei

    2010-01-01

    Nanocrystalline titanium dioxide powder was synthesized by in-flight oxidation of titanium dihydride (TiH 2 ) powder in a thermal plasma jet. TiH 2 powder was injected into the thermal plasma jet and allowed to react with oxygen injected downstream the jet. Characterization of the powder by various analytical tools indicated that the powder consisted of nano-sized titanium dioxide particles consisting predominantly of the anatase phase. It is suggested that the thermo-chemistry of the oxidation process contributes significantly to the formation of nano-sized titania. The large energy released during the oxidation process dissociates the TiO 2 particles into TiO (g) and titanium vapour, which recombine downstream with oxygen and form nano particles of TiO 2 .

  16. Synthesis and characterization of high volume fraction Al-Al2O3 nanocomposite powders by high-energy milling

    International Nuclear Information System (INIS)

    Prabhu, B.; Suryanarayana, C.; An, L.; Vaidyanathan, R.

    2006-01-01

    Al-Al 2 O 3 metal matrix composite (MMC) powders with volume fractions of 20, 30, and 50% Al 2 O 3 were synthesized by high-energy milling of the blended component powders. The particle sizes of Al 2 O 3 studied were 50 nm, 150 nm, and 5 μm. A uniform distribution of the Al 2 O 3 reinforcement in the Al matrix was successfully obtained after milling the powders for a period of 20 h at a ball-to-powder ratio of 10:1 in a SPEX mill. The uniform distribution of Al 2 O 3 in the Al matrix was confirmed by characterizing these nanocomposite powders by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray mapping, and X-ray diffraction (XRD) techniques

  17. ENTIRELY AQUEOUS SOLUTION-GEL ROUTE FOR THE PREPARATION OF ZIRCONIUM CARBIDE, HAFNIUM CARBIDE AND THEIR TERNARY CARBIDE POWDERS

    Directory of Open Access Journals (Sweden)

    Zhang Changrui

    2016-07-01

    Full Text Available An entirely aqueous solution-gel route has been developed for the synthesis of zirconium carbide, hafnium carbide and their ternary carbide powders. Zirconium oxychloride (ZrOCl₂.8H₂O, malic acid (MA and ethylene glycol (EG were dissolved in water to form the aqueous zirconium carbide precursor. Afterwards, this aqueous precursor was gelled and transformed into zirconium carbide at a relatively low temperature (1200 °C for achieving an intimate mixing of the intermediate products. Hafnium and the ternary carbide powders were also synthesized via the same aqueous route. All the zirconium, hafnium and ternary carbide powders exhibited a particle size of ∼100 nm.

  18. Separation of DR synthesized Ti-Mg Alloy by dissolution of waste by-products in acid media

    CSIR Research Space (South Africa)

    Mushove, T

    2010-06-01

    Full Text Available The objective of this work is to isolate synthesized Ti-Mg alloy powder through leaching out of MgO and any unreduced oxides of Titanium. Leaching media investigated are H2SO4, HCl and organic acids ascorbic acid/oxalic and L-cysteine /ascorbic...

  19. Antisolvent-assisted powder engineering for controlled growth of hybrid CH3NH3PbI3 perovskite thin films

    Directory of Open Access Journals (Sweden)

    Yong Chan Choi

    2017-02-01

    Full Text Available We develop antisolvent-assisted powder engineering for the controlled growth of hybrid inorganic-organic CH3NH3PbI3 (MAPbI3 perovskite thin films. The powders, which are used as the precursors for solution processing, are synthesized by pouring a MAPbI3 precursor solution into various antisolvents, such as dichloromethane, chloroform, diethyl ether, and toluene. Two types of powders having different colors are obtained, depending on the antisolvent used. The choice of the antisolvent used for synthesizing the powders strongly influences not only the phases of the powders but also the morphology and structure of the thin films subsequently fabricated by solution processing. This, in turn, affects the photovoltaic performance.

  20. New Strategies for Powder Compaction in Powder-based Rapid Prototyping Techniques

    NARCIS (Netherlands)

    Budding, A.; Vaneker, Thomas H.J.

    2013-01-01

    In powder-based rapid prototyping techniques, powder compaction is used to create thin layers of fine powder that are locally bonded. By stacking these layers of locally bonded material, an object is made. The compaction of thin layers of powder mater ials is of interest for a wide range of

  1. 21 CFR 520.1696a - Buffered penicillin powder, penicillin powder with buffered aqueous diluent.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Buffered penicillin powder, penicillin powder with... FORM NEW ANIMAL DRUGS § 520.1696a Buffered penicillin powder, penicillin powder with buffered aqueous diluent. (a) Specifications. When reconstituted, each milliliter contains penicillin G procaine equivalent...

  2. Separation of UO2 powder

    International Nuclear Information System (INIS)

    Ristic, M.M.

    1962-01-01

    This report deals with theoretical approach to separation process and describes the constructed separator with liquid medium. The separator was calibrated and tested with Al 3 O 3 and UO 2 . it has been concluded that it can be used for separation of powders with sufficient accuracy if the separation is performed for a longer period of time. The separated fractions were characterised by microscopic method and the UO 2 fraction additionally by sedimentation method

  3. Manufacture of uranium dioxide powder

    International Nuclear Information System (INIS)

    Becker, M.

    1976-01-01

    Uranium dioxide powder is prepared by the AUC (ammonium uranyl carbonate) method. Supplementing the known process steps, the AUC, after separation from the mother liquor, is washed with an ammonium hydrogen carbonate or an NH 4 OH solution and is subsequently post-treated with a liquid which reduces the surface tension of the residual water in an AUC. Such a liquid is, for instance, alcohol

  4. Biomimetic nanocrystalline apatite coatings synthesized by Matrix Assisted Pulsed Laser Evaporation for medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Visan, A. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Grossin, D. [CIRIMAT – Carnot Institute, University of Toulouse, ENSIACET, 4 Allée Emile Monso, 31030 Toulouse Cedex 4 (France); Stefan, N.; Duta, L.; Miroiu, F.M. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Stan, G.E. [National Institute of Materials Physics, RO-077125, Magurele-Ilfov (Romania); Sopronyi, M.; Luculescu, C. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Freche, M.; Marsan, O.; Charvilat, C. [CIRIMAT – Carnot Institute, University of Toulouse, ENSIACET, 4 Allée Emile Monso, 31030 Toulouse Cedex 4 (France); Ciuca, S. [Politehnica University of Bucharest, Faculty of Materials Science and Engineering, Bucharest (Romania); Mihailescu, I.N., E-mail: ion.mihailescu@inflpr.ro [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania)

    2014-02-15

    Highlights: • We report the deposition by MAPLE of biomimetic apatite coatings on Ti substrates. • This is the first report of MAPLE deposition of hydrated biomimetic apatite films. • Biomimetic apatite powder was synthesized by double decomposition process. • Non-apatitic environments, of high surface reactivity, are preserved post-deposition. • We got the MAPLE complete transfer as thin film of a hydrated, delicate material. -- Abstract: We report the deposition by Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique of biomimetic nanocrystalline apatite coatings on titanium substrates, with potential application in tissue engineering. The targets were prepared from metastable, nanometric, poorly crystalline apatite powders, analogous to mineral bone, synthesized through a biomimetic approach by double decomposition process. For the deposition of thin films, a KrF* excimer laser source was used (λ = 248 nm, τ{sub FWHM} ≤ 25 ns). The analyses revealed the existence, in synthesized powders, of labile non-apatitic mineral ions, associated with the formation of a hydrated layer at the surface of the nanocrystals. The thin film analyses showed that the structural and chemical nature of the nanocrystalline apatite was prevalently preserved. The perpetuation of the non-apatitic environments was also observed. The study indicated that MAPLE is a suitable technique for the congruent transfer of a delicate material, such as the biomimetic hydrated nanohydroxyapatite.

  5. Biomimetic nanocrystalline apatite coatings synthesized by Matrix Assisted Pulsed Laser Evaporation for medical applications

    International Nuclear Information System (INIS)

    Visan, A.; Grossin, D.; Stefan, N.; Duta, L.; Miroiu, F.M.; Stan, G.E.; Sopronyi, M.; Luculescu, C.; Freche, M.; Marsan, O.; Charvilat, C.; Ciuca, S.; Mihailescu, I.N.

    2014-01-01

    Highlights: • We report the deposition by MAPLE of biomimetic apatite coatings on Ti substrates. • This is the first report of MAPLE deposition of hydrated biomimetic apatite films. • Biomimetic apatite powder was synthesized by double decomposition process. • Non-apatitic environments, of high surface reactivity, are preserved post-deposition. • We got the MAPLE complete transfer as thin film of a hydrated, delicate material. -- Abstract: We report the deposition by Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique of biomimetic nanocrystalline apatite coatings on titanium substrates, with potential application in tissue engineering. The targets were prepared from metastable, nanometric, poorly crystalline apatite powders, analogous to mineral bone, synthesized through a biomimetic approach by double decomposition process. For the deposition of thin films, a KrF* excimer laser source was used (λ = 248 nm, τ FWHM ≤ 25 ns). The analyses revealed the existence, in synthesized powders, of labile non-apatitic mineral ions, associated with the formation of a hydrated layer at the surface of the nanocrystals. The thin film analyses showed that the structural and chemical nature of the nanocrystalline apatite was prevalently preserved. The perpetuation of the non-apatitic environments was also observed. The study indicated that MAPLE is a suitable technique for the congruent transfer of a delicate material, such as the biomimetic hydrated nanohydroxyapatite

  6. [Advances in studies on bear bile powder].

    Science.gov (United States)

    Zhou, Chao-fan; Gao, Guo-jian; Liu, Ying

    2015-04-01

    In this paper, a detailed analysis was made on relevant literatures about bear bile powder in terms of chemical component, pharmacological effect and clinical efficacy, indicating bear bile powder's significant pharmacological effects and clinical application in treating various diseases. Due to the complex composition, bear bile powder is relatively toxic. Therefore, efforts shall be made to study bear bile powder's pharmacological effects, clinical application, chemical composition and toxic side-effects, with the aim to provide a scientific basis for widespread reasonable clinical application of bear bile powder.

  7. Synthesis and characterization of ceramic powders of pure and doped with trivalent erbium barium tungstate

    International Nuclear Information System (INIS)

    Sousa, R.B. de; Nascimento, V.A. do; Matos, J. M.E. de; Santos, M.R.M.C.

    2014-01-01

    This research proposes the synthesis and characterization of pure and doped with Er"3"+ (1 and 2 %) barium tungstate powders prepared by the coprecipitation method. In order to characterize the obtained powders were used X-Ray Diffractometry, Raman Spectroscopy and Fourier Transform Infrared Spectroscopy. According to the standard XRD spectra, the crystals exhibited the presence of tetragonal scheelite structure without the presence of secondary phases. Raman spectra showed the presence of eleven vibrational modes and two modes were observed in the infrared spectra. The synthesized oxides showed good crystallinity and structurally ordered at short and long-range. (author)

  8. Structural and dielectric characterization of praseodymium-modified lead titanate ceramics synthesized by the OPM route

    Energy Technology Data Exchange (ETDEWEB)

    Pinto, Alexandre H., E-mail: alehp1@yahoo.com.br [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod. Washington Luis km 235, CP 676, Sao Carlos 13565-905, SP (Brazil); Souza, Flavio L., E-mail: fleandro.ufabc@gmail.com [Centro de Ciencias Naturais e Humanas, UFABC - Universidade Federal do ABC, Santo Andre 09210-170, SP (Brazil); Longo, Elson, E-mail: elson@iq.unesp.br [Department of Biochemistry, Chemistry Institute of Araraquara, UNESP - Sao Paulo State University, Rua Francisco Degni, CP 355, Araraquara 14801-907, SP (Brazil); Leite, Edson R., E-mail: derl@power.ufscar.br [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod. Washington Luis km 235, CP 676, Sao Carlos 13565-905, SP (Brazil); Camargo, Emerson R., E-mail: camargo@ufscar.br [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod. Washington Luis km 235, CP 676, Sao Carlos 13565-905, SP (Brazil)

    2011-10-17

    Highlights: {yields} Highly reactive nanosized powders of Pb(0.8)Pr(0.2)TiO(3) were obtained by the OPM route. {yields} Tetragonal phase was observed by X-ray diffraction and confirmed by Raman spectroscopy. {yields} SEM images showed powders partially sintered with particles of approximately 54 nm. {yields} Dielectric measurements show a normal behavior for the ferroelectric to paraelectric transition. - Abstract: Quasi-spherical nanoparticles of praseodymium-modified lead titanate powder (Pb{sub 0.80}Pr{sub 0.20}TiO{sub 3}) with an average size of 54.8 nm were synthesized successfully by the oxidant-peroxo method (OPM) and were used to prepare highly dense ceramic bodies which were sintered at 1100 and 1150 deg. C for 2 h. A tetragonal phase was identified in the powder and ceramic samples by X-ray powder diffraction and FT-Raman spectroscopy at room temperature. The fractured surface of the ceramic sample showed a high degree of densification with fairly uniform grain sizes. Dielectric constants measured in the range of 30-300 deg. C at different frequencies (120 Hz and at 1, 10 and 100 kHz) indicated that samples with 20 mol% praseodymium showed normal ferroelectric behavior regardless of the sintering temperature.

  9. Structural and dielectric characterization of praseodymium-modified lead titanate ceramics synthesized by the OPM route

    International Nuclear Information System (INIS)

    Pinto, Alexandre H.; Souza, Flavio L.; Longo, Elson; Leite, Edson R.; Camargo, Emerson R.

    2011-01-01

    Highlights: → Highly reactive nanosized powders of Pb(0.8)Pr(0.2)TiO(3) were obtained by the OPM route. → Tetragonal phase was observed by X-ray diffraction and confirmed by Raman spectroscopy. → SEM images showed powders partially sintered with particles of approximately 54 nm. → Dielectric measurements show a normal behavior for the ferroelectric to paraelectric transition. - Abstract: Quasi-spherical nanoparticles of praseodymium-modified lead titanate powder (Pb 0.80 Pr 0.20 TiO 3 ) with an average size of 54.8 nm were synthesized successfully by the oxidant-peroxo method (OPM) and were used to prepare highly dense ceramic bodies which were sintered at 1100 and 1150 deg. C for 2 h. A tetragonal phase was identified in the powder and ceramic samples by X-ray powder diffraction and FT-Raman spectroscopy at room temperature. The fractured surface of the ceramic sample showed a high degree of densification with fairly uniform grain sizes. Dielectric constants measured in the range of 30-300 deg. C at different frequencies (120 Hz and at 1, 10 and 100 kHz) indicated that samples with 20 mol% praseodymium showed normal ferroelectric behavior regardless of the sintering temperature.

  10. Synthesis of LiBOB Fine Powder to Increase Solubility

    Directory of Open Access Journals (Sweden)

    Etty Marti Wigayati

    2017-04-01

    Full Text Available Lithium bis (oxalate borate or LiBOB compound has captured interest of researchers, because it is potentially viable to be used as electrolyte salt in lithium-ion battery system. This compound is easy to synthesize and considered to be more environmentally friendly compared to conventional electrolyte salt because LiBOB does not contain halogen element. This research focused on the synthesis of LiBOB fine powder, which main purpose is improving LiBOB salt solubility in liquid electrolyte solution. This will aid the ion transfer between electrodes which in turn will increase the electrolyte performance. Solid state reaction was employed in this experiment. Synthesis of LiBOB compound was performed by reacting oxalic acid dihydrate, lithium hydroxide monohydrate, and boric acid. The resulting powder was then processed into fine powder using ball milling technique with varying milling time (0, 6, 10, and 13 hour. Microstructure of the sample was then analyzed to obtain information regarding phase formation, functional groups, grain surface morphology, surface area, pore volume, solubility, and ionic conductivity. The analysis shown that LiBOB and LiBOB hydrate phase was formed during the reaction, there was no changed in existing phase during milling process, crystallinity index was shifted to lower value but there was no difference in functional groups. Highest value in surface area was found to be 83.11 m2/g, with pore volume of 1.21311e+02 A at 10 hours milling. Smaller powder size resulted in higher solubility, unfortunately the ionic conductivity was found to be decreased.

  11. Behaviour of CaO coating of gas atomized Mg powders using mechanical milling process

    International Nuclear Information System (INIS)

    Kim, Sun-Mi; Kim, Yong Hwan; Kim, Young Do; Kim, Taek-Soo

    2011-01-01

    Highlights: → This work is very new, since behaviour of CaO coating with milling time as desulfurizer is not frequently reported. → The manuscript reports the new manner of Mg powders desulfurizer development by the innovative process. - Abstract: In order to synthesize a thermally stable Mg powder as a desulfurizer of iron, pure Mg was gas atomized to powders and coated by CaO powders, to produce a thermally stable desulfurizer using a mechanical milling process. Since the effect of desulfurization is dependent on the degree of surface modification, coating behaviours such as the size, morphology and layer thickness were investigated as a function of milling condition. As the milling conducted from 10 min to 30 min, 1 h, 3 h, 6 h, 12 h, CaO particles began to stick on the surface of Mg powders. The layer of CaO formed from 1 h milling was about 17 μm thick and gradually thickened to be 28 μm, 32 μm and 37 μm with increasing the milling time to 3 h, 6 h and 12 h, respectively. The shape of coated powder became more spherical after 1 h milling, being mostly spherical after 6 h. Desulfurization rate and uniformity were evaluated for the various thickness of the coating layer.

  12. Preparation of soft-agglomerated nano-sized ceramic powders by sol-gel combustion process

    International Nuclear Information System (INIS)

    Feng, Q.; Ma, X.H.; Yan, Q.Z.; Ge, C.C.

    2009-01-01

    The soft-agglomerated Gd 2 BaCuO 5 (Gd211) nano-powders were synthesized by sol-gel combustion process with binary ligand and the special pretreatment on gel. The mechanism of the formation of weakly agglomerated structure was studied in detail. The results showed that network structure in gelation process was found to be a decisive factor for preventing agglomeration of colloidal particles. The removal of free water, coordinated water, and most of hydroxyl groups during pretreatment further inhibited the formation of hydrogen bonds between adjacent particles. The soft-agglomeration of the particles was confirmed by isolated particles in calcined Gd211 powders and in green compact, a narrow monomodal pore size distribution of the green compact and the low agglomeration coefficient of the calcined Gd211 powder. Extension this process to synthesis of BaCeO 3 , BaTiO 3 and Ce 0.8 Sm 0.2 O 1.9 powders, also led to weakly agglomerated nano-powders. It suggests that this method represents a powerful and facile method for the creation of doped and multi-component nano-sized ceramic powders.

  13. Roller compaction of moist pharmaceutical powders.

    Science.gov (United States)

    Wu, C-Y; Hung, W-L; Miguélez-Morán, A M; Gururajan, B; Seville, J P K

    2010-05-31

    The compression behaviour of powders during roller compaction is dominated by a number of factors, such as process conditions (roll speed, roll gap, feeding mechanisms and feeding speed) and powder properties (particle size, shape, moisture content). The moisture content affects the powder properties, such as the flowability and cohesion, but it is not clear how the moisture content will influence the powder compression behaviour during roller compaction. In this study, the effect of moisture contents on roller compaction behaviour of microcrystalline cellulose (MCC, Avicel PH102) was investigated experimentally. MCC samples of different moisture contents were prepared by mixing as-received MCC powder with different amount of water that was sprayed onto the powder bed being agitated in a rotary mixer. The flowability of these samples were evaluated in terms of the poured angle of repose and flow functions. The moist powders were then compacted using the instrumented roller compactor developed at the University of Birmingham. The flow and compression behaviour during roller compaction and the properties of produced ribbons were examined. It has been found that, as the moisture content increases, the flowability of moist MCC powders decreases and the powder becomes more cohesive. As a consequence of non-uniform flow of powder into the compaction zone induced by the friction between powder and side cheek plates, all produced ribbons have a higher density in the middle and lower densities at the edges. For the ribbons made of powders with high moisture contents, different hydration states across the ribbon width were also identified from SEM images. Moreover, it was interesting to find that these ribbons were split into two halves. This is attributed to the reduction in the mechanical strength of moist powder compacts with high moisture contents produced at high compression pressures. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  14. PIXE analysis of powdered milk

    International Nuclear Information System (INIS)

    Hallak, A.B.

    1983-01-01

    An accelerator-based study, using proton-induced x-ray emission (PIXE) was performed on four full-cream and four half-cream brands of powdered milk commonly consumed in Jordan. The elements detected in the samples are S, Cl, K, Ca, Fe, Cu, Zn, Br and Rb. The significance of some of these elements is discussed from the viewpoint of nutrition and also their effect on milk processing and dairy technology. The standard reference milk sample, A-11, which is distributed by IAEA was also examined, and the results for trace elements detected are compared with the values certified by IAEA. (author)

  15. Atomization process for metal powder

    International Nuclear Information System (INIS)

    Lagutkin, Stanislav; Achelis, Lydia; Sheikhaliev, Sheikhali; Uhlenwinkel, Volker; Srivastava, Vikas

    2004-01-01

    A new atomization process has been developed, which combines pressure and gas atomization. The melt leaves the pressure nozzle as a hollow thin film cone. After the pre-filming step, the melt is atomized by a gas stream delivered by a ring nozzle. The objectives of this investigation are to achieve a narrow size distribution and low specific gas consumption compared to conventional gas atomization techniques. Both lead to a higher efficiency and low costs. Tin and some alloys have been atomized successfully with this technique. The mass median diameters from different experiments are between 20 and 100 μm. Sieving analysis of the tin powder shows close particle size distributions

  16. New Strategies for Powder Compaction in Powder-based Rapid Prototyping Techniques

    OpenAIRE

    Budding, A.; Vaneker, T.H.J.

    2013-01-01

    In powder-based rapid prototyping techniques, powder compaction is used to create thin layers of fine powder that are locally bonded. By stacking these layers of locally bonded material, an object is made. The compaction of thin layers of powder mater ials is of interest for a wide range of applications, but this study solely focuses on the application for powder -based three-dimensional printing (e.g. SLS, 3DP). This research is primarily interested in powder compaction for creating membrane...

  17. Thermoluminescent properties of ZnS:Mn nanocrystalline powders

    International Nuclear Information System (INIS)

    Ortiz-Hernández, Arturo Agustín; Méndez García, Víctor Hugo; Pérez Arrieta, María Leticia; Ortega Sígala, José Juan

    2015-01-01

    Thermoluminescent ZnS nanocrystals doped with Mn 2+ ions were synthesized by chemical co-precipitation method. From X-ray diffraction studies it was observed that the synthesized nanoparticles have cubic zinc blende structure with average sizes of about 40–50 nm. Morphology was analyzed by TEM. Photoluminescence studies showed two transitions, one of them close to 396 nm and other close to 598 nm, which is enhanced with increasing dopant concentration, this behavior was also observed in the cathodoluminescence spectrum. The thermoluminescence gamma dose-response has linear behavior over dose range 5–100 mGy, the glow curve structure shows two glow peaks at 436 K and at 518 K that were taken into account to calculate the kinetic parameters using the Computerized Glow Curve Deconvolution procedure. - Highlights: • Nanocrystals in powder of ZnS:Mn were synthesized using the co-precipitation method. • The integrated TL spectra has a linear behavior on the dose range 5–100 mGy of γ-radiation. • The kinetic parameters were obtained by the CGCD procedure. • Results support the possible use of nanocrystalline ZnS:Mn as a new γ-dose nanoTLD

  18. In-house characterization of protein powder

    DEFF Research Database (Denmark)

    Hartmann, Christian Grundahl; Nielsen, Ole Faurskov; Ståhl, Kenny

    2010-01-01

    X-ray powder diffraction patterns of lysozyme and insulin were recorded on a standard in-house powder diffractometer. The experimental powder diffraction patterns were compared with patterns calculated from Protein Data Bank coordinate data. Good agreement was obtained by including straightforward...... to include calculated H-atom positions did not improve the overall fit and was abandoned. The method devised was shown to be a quick and convenient tool for distinguishing precipitates and polymorphs of proteins....

  19. Cryomilling of Thermoplastic Powder for Prepreg Applications

    Science.gov (United States)

    2013-09-01

    Cryomilling of Thermoplastic Powder for Prepreg Applications by Brian Parquette, Anit Giri, Daniel J. O’Brien, Sarah Brennan, Kyu Cho, and...MD 21005-5066 ARL-TR-6591 September 2013 Cryomilling of Thermoplastic Powder for Prepreg Applications Brian Parquette and Sarah Brennan...COVERED (From - To) 1 March 2012–30 May 2013 4. TITLE AND SUBTITLE Cryomilling of Thermoplastic Powder for Prepreg Applications 5a. CONTRACT

  20. Method of producing radioactive carbon powder

    International Nuclear Information System (INIS)

    Imamura, Y.

    1980-01-01

    Carbon powder, placed in a hermetically closed apparatus under vacuum together with radium ore, adsorbs radon gas emanating from the radium ore thus producing a radioactive carbonaceous material, the radioactivity of which is due to the presence of adsorbed radon. The radioactive carbon powder thus obtained has excellent therapeutical efficacy and is suitable for a variety of applications because of the mild radioactivity of radon. Radium ore permits substantially limitlessly repeated production of the radioactive carbon powder

  1. Powder handling for automated fuel processing

    International Nuclear Information System (INIS)

    Frederickson, J.R.; Eschenbaum, R.C.; Goldmann, L.H.

    1989-01-01

    Installation of the Secure Automated Fabrication (SAF) line has been completed. It is located in the Fuel Cycle Plant (FCP) at the Department of Energy's (DOE) Hanford site near Richland, Washington. The SAF line was designed to fabricate advanced reactor fuel pellets and assemble fuel pins by automated, remote operation. This paper describes powder handling equipment and techniques utilized for automated powder processing and powder conditioning systems in this line. 9 figs

  2. Comparison of Two Powder Processing Techniques on the Properties of Cu-NbC Composites

    Directory of Open Access Journals (Sweden)

    B. D. Long

    2014-01-01

    Full Text Available An in situ Cu-NbC composite was successfully synthesized from Cu, Nb, and C powders using ball milling and high pressure torsion (HPT techniques. The novelty of the new approach, HPT, is the combination of high compaction pressure and large shear strain to simultaneously refine, synthesize, and consolidate composite powders at room temperature. The HPTed Cu-NbC composite was formed within a short duration of 20 min without Fe contamination from the HPT’s die. High porosity of 3–9%, Fe and niobium oxidations, from grinding media and ethanol during ball milling led to low electrical conductivity of the milled Cu-NbC composite. The electrical conductivity of the HPTed Cu-NbC composite showed a value 50% higher than that of milled Cu-NbC composite of the same composition.

  3. Development of MnBi permanent magnet: Neutron diffraction of MnBi powder

    Energy Technology Data Exchange (ETDEWEB)

    Cui, J., E-mail: jun.cui@pnnl.gov; Choi, J. P.; Li, G.; Polikarpov, E.; Darsell, J. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354 (United States); Kramer, M. J.; Zarkevich, N. A.; Wang, L. L.; Johnson, D. D. [Materials Sciences and Engineering Division, Ames Laboratory, Ames, Iowa 50011 (United States); Marinescu, M. [Electron Energy Corporation, Landisville, Pennsylvania 17538 (United States); Huang, Q. Z.; Wu, H. [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102 (United States); Vuong, N. V.; Liu, J. P. [Department of Physics, University of Texas at Arlington, Arlington, Texas 76019 (United States)

    2014-05-07

    MnBi attracts great attention in recent years for its great potential as permanent magnet materials. MnBi phase is difficult to obtain because of the rather drastic peritectic reaction between Mn and Bi. In this paper, we report our effort on synthesizing high purity MnBi compound using conventional powder metallurgical approaches. Neutron diffraction was carried out to investigate the crystal and nuclear structure of the obtained powder. The result shows that the purity of the obtained powder is about 91 wt. % at 300 K, and the magnetic moment of the Mn atom in MnBi lattice is 4.424 and 4.013 μ{sub B} at 50 K and 300 K, respectively.

  4. Bulk synthesis of nanocrystalline urania powders by citrate gel-combustion method

    Science.gov (United States)

    Sanjay Kumar, D.; Ananthasivan, K.; Venkata Krishnan, R.; Amirthapandian, S.; Dasgupta, Arup

    2016-01-01

    Bulk quantities (60 g) of nanocrystalline (nc) free flowing urania powders with crystallite size ranging from 38 to 252 nm have been synthesized for the first time by the citrate gel combustion method. A systematic study of the influence of the fuel (citric acid) to oxidant (nitrate) ratio (R) on the characteristics of the urania powders has been carried out for the first time. Mixture with an "R" value of 0.25 exhibited a vigorous auto-ignition reaction. This reaction was investigated with Differential Scanning Calorimetry (DSC) and in-situ thermogravimetry coupled with differential thermal analysis and mass spectrometry (TG-DTA-MS). The bulk density, specific surface area, X-ray crystallite size, residual carbon and size distribution of particles of this powder were unique. Microscopic and microstructural investigation of selected samples revealed the presence of nanocrystals with irregular exfoliated morphology; their Electron Energy Loss Spectra testified the covalency of the U-O bond.

  5. Development of MnBi permanent magnet: Neutron diffraction of MnBi powder

    Energy Technology Data Exchange (ETDEWEB)

    Cui, J; Choi, JP; Li, G; Polikarpov, E; Darsell, J; Kramer, MJ; Zarkevich, NA; Wang, LL; Johnson, DD; Marinescu, M; Huang, QZ; Wu, H; Vuong, NV; Liu, JP

    2014-05-07

    MnBi attracts great attention in recent years for its great potential as permanent magnet materials. MnBi phase is difficult to obtain because of the rather drastic peritectic reaction between Mn and Bi. In this paper, we report our effort on synthesizing high purity MnBi compound using conventional powder metallurgical approaches. Neutron diffraction was carried out to investigate the crystal and nuclear structure of the obtained powder. The result shows that the purity of the obtained powder is about 91 wt. % at 300 K, and the magnetic moment of the Mn atom in MnBi lattice is 4.424 and 4.013 mu(B) at 50 K and 300 K, respectively. (C) 2014 AIP Publishing LLC.

  6. NiTiO3 powders obtained by polymeric precursor method: Synthesis and characterization

    International Nuclear Information System (INIS)

    Lopes, K.P.; Cavalcante, L.S.; Simoes, A.Z.; Varela, J.A.; Longo, E.; Leite, E.R.

    2009-01-01

    Nickel titanate (NiTiO 3 ) powders were synthesized by the polymeric precursor method after thermal treatment at different temperatures for 2 h in air atmosphere. The decomposition of the precursors was monitored by differential scanning calorimetry and thermogravimetric analysis. The NiTiO 3 powders presented a reduction in the specific surface area and increase of the average particle size with the evolution of the temperature. The structural evolution of NiTiO 3 phase was accompanied by X-ray diffraction and Fourier transform Raman spectroscopy. By scanning electron microscopy was revealed the agglomerated nature of very fine particles of NiTiO 3 powders annealed from 600 to 1000 deg. C

  7. AlN powder synthesis via nitriding reaction of aluminum sub-chloride

    Energy Technology Data Exchange (ETDEWEB)

    Ohashi, T.; Nishida, T.; Sugiura, M. (Waseda Univ., Tokyo (Japan). Graduate School); Fuwa, A. (Waseda Univ., Tokyo (Japan))

    1993-06-01

    In order to obtain the pertinent properties of aluminium nitride in its sintered form, it is desirable to have powders of finer sizes with narrower size distribution and higher purity, thereby making the sintering processing easier and the final body denser. Instead of using sublimated aluminum tri-chloride vapor (AlCl3) as an aluminum source in the vapor phase nitriding reaction, the mixed aluminum chloride vapor consisted of aluminum tri-chloride, bi-chloride and mono-chloride are used in the reaction with ammonia at temperatures of 1000 and 1200K. The mixed chloride vapors are produced by reacting chlorine with molten aluminum at 1000 or 1200K under atmospheric pressure. The reaction of this mixed chloride vapor with ammonia is then experimentally investigated to study the aluminum nitride powder morphology. The aluminum nitride powders synthesized under various ammonia concentrations are characterized for size distribution, mean particle size and particle morphology. 24 refs., 8 figs., 2 tabs.

  8. Synthesis of nano-sized hydroxyapatite powders through solution combustion route under different reaction conditions

    International Nuclear Information System (INIS)

    Ghosh, Samir Kumar; Roy, Sujit Kumar; Kundu, Biswanath; Datta, Someswar; Basu, Debabrata

    2011-01-01

    Calcium hydroxyapatite, Ca 10 (PO 4 ) 6 (OH) 2 (HAp) was synthesized by combustion in the aqueous system containing calcium nitrate-diammonium hydrogen orthophosphate with urea and glycine as fuels. These ceramics are important materials for biomedical applications. Thermo-gravimetric and differential thermal analysis were employed to understand the nature of synthesis process during combustion. Effects of different process parameters namely, nature of fuel (urea and glycine), fuel to oxidizer ratio (0.6-4.0) and initial furnace temperature (300-700 o C) on the combustion behavior as well as physical properties of as-formed powders were investigated. A series of combustion reactions were carried out to optimize the reaction parameters for synthesis of nano-sized HAp powders. The combustion temperature (T f ) for the oxidant and fuels were calculated to be 896 deg. C and 1035 deg. C for the stoichiometric system of urea and glycine respectively. The stoichiometric glycine-calcium nitrate produced higher flame temperature (both calculated and measured) and powder with lower specific surface area (8.75 m 2 /g) compared to the stoichiometric urea-calcium nitrate system (10.50 m 2 /g). Fuel excess combustion in both glycine and urea produced powders with higher surface area. Nanocrystalline HAp powder could be synthesized in situ with a large span of fuel to oxidizer ratio (φ) in case of urea system (0.8 < φ < 4) and (0.6 < φ < 1.5) for the glycine system. Calcium hydroxyapatite particles having diameters ranging between 20 nm and 120 nm could be successfully synthesized through optimized process variable.

  9. PRODUCTION, DIELECTRIC PROPERTY AND MICROWAVE ABSORPTION PROPERTY OF SiC(Fe SOLID SOLUTION POWDER BY SOL-GEL METHOD

    Directory of Open Access Journals (Sweden)

    XIAOLEI SU

    2014-03-01

    Full Text Available SiC(Fe solid solution powders were synthesized by sol–gel method under different reaction time, using methyltriethoxysilane as the silicon and carbon source and analytic ferric chloride as the dopant, respectively. The synthesized powders have been characterized by XRD, SEM and Raman spectra. Results show that the lattice constant decreases with increasing reaction time. The electric permittivities of SiC samples were determined in the frequency range of 8.2 ~ 12.4 GHz. Results show that the permittivity of SiC decreases with increasing reaction time. The SiC(Fe solid solution powder with reaction time of 4 h with 2 mm thickness exhibit the best microwave absorption property in X-band range (8.2 - 12.4 GHz. The microwave absorption mechanism has been discussed.

  10. Preparation techniques for ceramic waste form powder

    International Nuclear Information System (INIS)

    Hash, M.C.; Pereira, C.; Lewis, M.A.

    1997-01-01

    The electrometallurgical treatment of spent nuclear fuels result in a chloride waste salt requiring geologic disposal. Argonne National Laboratory (ANL) is developing ceramic waste forms which can incorporate this waste. Currently, zeolite- or sodalite-glass composites are produced by hot isostatic pressing (HIP) techniques. Powder preparations include dehydration of the raw zeolite powders, hot blending of these zeolite powders and secondary additives. Various approaches are being pursued to achieve adequate mixing, and the resulting powders have been HIPed and characterized for leach resistance, phase equilibria, and physical integrity

  11. Effect of surface energy on powder compactibility.

    Science.gov (United States)

    Fichtner, Frauke; Mahlin, Denny; Welch, Ken; Gaisford, Simon; Alderborn, Göran

    2008-12-01

    The influence of surface energy on the compactibility of lactose particles has been investigated. Three powders were prepared by spray drying lactose solutions without or with low proportions of the surfactant polysorbate 80. Various powder and tablet characterisation procedures were applied. The surface energy of the powders was characterized by Inverse Gas Chromatography and the compressibility of the powders was described by the relationship between tablet porosity and compression pressure. The compactibility of the powders was analyzed by studying the evolution of tablet tensile strength with increasing compaction pressure and porosity. All powders were amorphous and similar in particle size, shape, and surface area. The compressibility of the powders and the microstructure of the formed tablets were equal. However, the compactibility and dispersive surface energy was dependent of the composition of the powders. The decrease in tablet strength correlated to the decrease in powder surface energy at constant tablet porosities. This supports the idea that tablet strength is controlled by formation of intermolecular forces over the areas of contact between the particles and that the strength of these bonding forces is controlled by surface energy which, in turn, can be altered by the presence of surfactants.

  12. Effect of powder geometry on densification

    International Nuclear Information System (INIS)

    Spasskij, M.R.; Spasskaya, I.A.; Shatalova, I.G.; Shchukin, E.D.

    1979-01-01

    The effect of particle shape and size composition on the processes of powder vibratory compacting is considered. Using microstress measurements in compacted structures of conglomerated and disintegrated tungsten powders as well as powder strength testing the existence of a zone of transition from a structural deformation to a plastic one has been shown. The formation of phase interparticle contacts of practically stable strength (approximately 5-6 dyn) is a characteristic feature of the zone. The width of the transition zone greatly depends upon geometrical powder properties; 55-65 % for conglomerated tungsten, 63-66 % for integrated tungsten

  13. Safety consideration when handling metal powders

    CSIR Research Space (South Africa)

    Benson, JM

    2012-03-01

    Full Text Available to some form of irritation or allergic reaction (e.g. dermatitis). In the case of nano-powders, the particles can penetrate the skin and become absorbed into cells in various parts of the body, including the brain � Eye contact, resulting in a... powders, and thus data is often limited to various ailments that have been reported for people working with that particular powder (amongs other things). There are three ways that powders can interact with the body: � Skin contact, which may lead...

  14. Hydrothermal synthesis and characterization of hydroxyapatite and fluorhydroxyapatite nano-size powders

    International Nuclear Information System (INIS)

    Montazeri, Leila; Javadpour, Jafar; Shokrgozar, Mohammad Ali; Bonakdar, Shahin; Javadian, Sayfoddin

    2010-01-01

    Pure hydroxyapatite (HAp) and fluoride-containing apatite powders (FHAp) were synthesized using a hydrothermal method. The powders were assessed by x-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscope (SEM) and F-selective electrode. X-ray diffraction results revealed the formation of single phase apatite structure for all the compositions synthesized in this work. However, the addition of a fluoride ion led to a systematic shift in the (3 0 0) peak of the XRD pattern as well as modifications in the FTIR spectra. It was found that the efficiency of fluoride ion incorporation decreased with the increase in the fluoride ion content. Fluorine incorporation efficiency was around 60% for most of the FHAp samples prepared in the current study. Smaller and less agglomerated particles were obtained by fluorine substitution. The bioactivity of the powder samples with different fluoride contents was compared by performing cell proliferation, alkaline phosphatase (ALP) and Alizarin red staining assays. Human osteoblast cells were used to assess the cellular responses to the powder samples in this study. Results demonstrated a strong dependence of different cell activities on the level of fluoridation.

  15. Combustion synthesis of nanocrystalline ceria (CeO2) powders by a dry route

    International Nuclear Information System (INIS)

    Hwang, C.-C.; Huang, T.-H.; Tsai, J.-S.; Lin, C.-S.; Peng, C.-H.

    2006-01-01

    In this study, ceria (CeO 2 ) powders were synthesized with 50 g per batch via a combustion technique using two kinds of starting materials-urea [(NH 2 ) 2 CO] (as a fuel) and ceric ammonium nitrate [Ce(NH 4 ) 2 (NO 3 ) 6 ] (acting as both the source of cerium ion and an oxidizer). The starting materials were mixed thoroughly without adding water, and then ignited in the air at room temperature. It underwent a self-combustion process with a large amount of smoke, a voluminous loose product. The as-synthesized powders were characterized by X-ray diffraction (XRD) analysis, transmission electron microscope (TEM), scanning electron microscope (SEM), CHN elemental analyzer, surface area measurements, and sinterability. Experimental results revealed that the nanocrystalline CeO 2 powders with low impurity content ( 2 /g and ∼25 nm, respectively, through the stoichiometric fuel/oxidizer ratio reaction. The powder, when cold pressed and sintered in the air at 1250 deg. C for 1 h, was measured to attain the sintered density ∼92% of theoretical density having submicron grain size. In addition, the thermal decomposition and combustion process of the reactant mixture were investigated using thermogravimetry (TG), differential scanning calorimetry (DSC), and mass spectrometry (MS) techniques simultaneously. Based on the results of thermal analysis, a possible mechanism concerning the combustion reaction is proposed

  16. Sintering of B{sub 4}C powder obtained by a modified carbo-thermal reaction

    Energy Technology Data Exchange (ETDEWEB)

    Rocha, R.M.; Kazumi, M.H.; Goncalves, D.P.; Melo, F.C.L. [Centro Tecnico Aeroespacial (CTA) - Instituto de Aeronautica e Espaco, Praca Marechal Eduardo Gomes, 50 Campus do CTA - Vila das Acacias, 12228-904 Sao Jose dos Campos-SP (Brazil)

    2005-07-01

    Boron carbide is one of the hardest materials and a highly refractory material that is of great interest for structural, electronic and nuclear applications. B{sub 4}C is commercially manufactured by the carbo-thermal reduction of a mixture of boron oxide (B{sub 2}O{sub 3}) in an batch electric arc furnace process. However the carbo-thermal reaction on the stoichiometric starting composition results an excess carbon residue because of the boron loss in the form of B{sub 2}O{sub 2}. Thus, a modified carbo-thermal reaction is applied with an excess B{sub 2}O{sub 3} to compensate the loss and to obtain stoichiometric powders. The aim of this work is to study the sinterability of this powder with the lower carbon residue acting as sintering additive. Pressureless sintering in the temperatures of 1900 deg. C/30 min and 2100 deg. C/30 min in argon atmosphere were applied. The synthesized powders were analysed by XRD and SEM. Density of 94% of theoretical density was achieved for sample prepared with the powder obtained with 50% B{sub 2}O{sub 3} excess synthesized at 1700 deg. C/15 min. (authors)

  17. Sintering of B4C powder obtained by a modified carbo-thermal reaction

    International Nuclear Information System (INIS)

    Rocha, R.M.; Kazumi, M.H.; Goncalves, D.P.; Melo, F.C.L.

    2005-01-01

    Boron carbide is one of the hardest materials and a highly refractory material that is of great interest for structural, electronic and nuclear applications. B 4 C is commercially manufactured by the carbo-thermal reduction of a mixture of boron oxide (B 2 O 3 ) in an batch electric arc furnace process. However the carbo-thermal reaction on the stoichiometric starting composition results an excess carbon residue because of the boron loss in the form of B 2 O 2 . Thus, a modified carbo-thermal reaction is applied with an excess B 2 O 3 to compensate the loss and to obtain stoichiometric powders. The aim of this work is to study the sinterability of this powder with the lower carbon residue acting as sintering additive. Pressureless sintering in the temperatures of 1900 deg. C/30 min and 2100 deg. C/30 min in argon atmosphere were applied. The synthesized powders were analysed by XRD and SEM. Density of 94% of theoretical density was achieved for sample prepared with the powder obtained with 50% B 2 O 3 excess synthesized at 1700 deg. C/15 min. (authors)

  18. Structural evolution of Fe-50 at.% Al powders during mechanical alloying and subsequent annealing processes

    International Nuclear Information System (INIS)

    Haghighi, Sh. Ehtemam; Janghorban, K.; Izadi, S.

    2010-01-01

    Iron aluminides, despite having desirable properties like excellent corrosion resistance, present low room-temperature ductility and low strength at high temperatures. Mechanical alloying as a capable process to synthesize nanocrystalline materials is under consideration to modify these drawbacks. In this study, the microstructure of iron aluminide powders synthesized by mechanical alloying and subsequent annealing was investigated. Elemental Fe and Al powders with the same atomic percent were milled in a planetary ball mill for 15 min to 100 h. The powder milled for 80 h was annealed at temperatures of 300, 500 and 700 o C for 1 h. The alloyed powders were disordered Fe(Al) solid solutions which were transformed to FeAl intermetallic after annealing. The effect of the milling time and annealing treatment on structural parameters, such as crystallite size, lattice parameter and lattice strain was evaluated by X-ray diffraction. Typically, these values were 15 nm, 2.92 A and 3.1% for the disordered Fe(Al) solid solution milled for 80 h and were 38.5 nm, 2.896 A and 1.2% for the FeAl intermetallic annealed at 700 o C, respectively.

  19. Perception of Paralinguistic Traits in Synthesized Voices

    DEFF Research Database (Denmark)

    Baird, Alice Emily; Hasse Jørgensen, Stina; Parada-Cabaleiro, Emilia

    2017-01-01

    Along with the rise of artificial intelligence and the internet-of-things, synthesized voices are now common in daily–life, providing us with guidance, assistance, and even companionship. From formant to concatenative synthesis, the synthesized voice continues to be defined by the same traits we...

  20. Composites comprising biologically-synthesized nanomaterials

    Science.gov (United States)

    Curran, Seamus; Dias, Sampath; Blau, Werner; Wang, Jun; Oremland, Ronald S; Baesman, Shaun

    2013-04-30

    The present disclosure describes composite materials containing a polymer material and a nanoscale material dispersed in the polymer material. The nanoscale materials may be biologically synthesized, such as tellurium nanorods synthesized by Bacillus selenitireducens. Composite materials of the present disclosure may have optical limiting properties and find use in optical limiting devices.

  1. Synthesis of nano-sized amorphous boron powders through active dilution self-propagating high-temperature synthesis method

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jilin [The State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Gu, Yunle [School of Material Science and Engineering, Wuhan Institute of Technology, Wuhan 430073 (China); Li, Zili [The State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Wang, Weimin, E-mail: wangwm@hotmail.com [The State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Fu, Zhengyi [The State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China)

    2013-06-01

    Graphical abstract: Nano-sized amorphous boron powders were synthesized by active dilution self-propagating high-temperature synthesis (SHS) method. The effects of endothermic reaction rate, the possible chemical reaction mechanism and active dilution model for synthesis of the product were also discussed. Highlights: ► Nano-sized amorphous boron powders were synthesized by active dilution self-propagating high-temperature synthesis method. ► The morphology, particle size and purity of the samples could be effectively controlled via changing the endothermic rate. ► The diluter KBH{sub 4} played an important role in active dilution synthesis of amorphous nano-sized boron powders. ► The active dilution method could be further popularized and become a common approach to prepare various inorganic materials. - Abstract: Nano-sized amorphous boron powders were synthesized by active dilution self-propagating high-temperature synthesis (SHS) method at temperatures ranging from 700 °C to 850 °C in a SHS furnace using Mg, B{sub 2}O{sub 3} and KBH{sub 4} as raw materials. Samples were characterized by X-ray powder diffraction (XRD), Laser particle size analyzer, Fourier transform infrared spectra (FTIR), X-ray energy dispersive spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission TEM (HRTEM). The boron powders demonstrated an average particle size of 50 nm with a purity of 95.64 wt.%. The diluter KBH{sub 4} played an important role in the active dilution synthesis of amorphous nano-sized boron powders. The effects of endothermic reaction rate, the possible chemical reaction mechanism and active dilution model for synthesis of the product were also discussed.

  2. Synthesis of nano-sized amorphous boron powders through active dilution self-propagating high-temperature synthesis method

    International Nuclear Information System (INIS)

    Wang, Jilin; Gu, Yunle; Li, Zili; Wang, Weimin; Fu, Zhengyi

    2013-01-01

    Graphical abstract: Nano-sized amorphous boron powders were synthesized by active dilution self-propagating high-temperature synthesis (SHS) method. The effects of endothermic reaction rate, the possible chemical reaction mechanism and active dilution model for synthesis of the product were also discussed. Highlights: ► Nano-sized amorphous boron powders were synthesized by active dilution self-propagating high-temperature synthesis method. ► The morphology, particle size and purity of the samples could be effectively controlled via changing the endothermic rate. ► The diluter KBH 4 played an important role in active dilution synthesis of amorphous nano-sized boron powders. ► The active dilution method could be further popularized and become a common approach to prepare various inorganic materials. - Abstract: Nano-sized amorphous boron powders were synthesized by active dilution self-propagating high-temperature synthesis (SHS) method at temperatures ranging from 700 °C to 850 °C in a SHS furnace using Mg, B 2 O 3 and KBH 4 as raw materials. Samples were characterized by X-ray powder diffraction (XRD), Laser particle size analyzer, Fourier transform infrared spectra (FTIR), X-ray energy dispersive spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission TEM (HRTEM). The boron powders demonstrated an average particle size of 50 nm with a purity of 95.64 wt.%. The diluter KBH 4 played an important role in the active dilution synthesis of amorphous nano-sized boron powders. The effects of endothermic reaction rate, the possible chemical reaction mechanism and active dilution model for synthesis of the product were also discussed

  3. New detectors for powders diagrams

    International Nuclear Information System (INIS)

    Convert, P.

    1975-01-01

    During the last few years, all the classical neutron diffractometers for powders have used one or maybe a few counters. So, it takes a long time to obtain a diagram which causes many disadvantages: 1) very long experiments: one or two days (or flux on the sample about 10 6 n/cm 2 /a); 2) necessity of big samples: many cm 3 ; 3) necessity of having the whole diagram before changing anything in the experiment: magnetic field, temperature, quality of the sample; 4) necessity of having collimators of a few times ten minutes to obtain correct statistics in the diagram. Because of these disadvantages, several attempts have been made to speed up the experimental procedure such as using more counters, the detection of neutrons on a resistive wire, etc. In Grenoble, new position-sensitive detectors have been constructed using a digital technique

  4. Reflection measurements for luminescent powders

    Science.gov (United States)

    Kroon, R. E.

    2018-04-01

    Luminescent materials are useful in applications varying from lighting and display technologies to document security features and medical research, amongst many others. Measurement of the excitation range is an important consideration, and absorption bands are often determined from a decrease in the measured diffuse reflectance of the material using a ultraviolet-visible (UV-vis) spectrophotometer with an integrating sphere. Such a system may provide questionable results when used to measure the reflectance of a luminescence material, which is demonstrated for a Tb doped silica phosphor, because the system cannot differentiate between the reflected light and luminescence. It is shown that more reliable results are achieved for this phosphor by measuring the reflectance using a synchronous zero-offset scan in a fluorescence spectrometer equipped with an integrating sphere. This method is therefore recommended instead of traditional reflectance measurements using a UV-vis spectrophotometer for luminescent powders.

  5. Advances in powder diffraction crystallography

    International Nuclear Information System (INIS)

    Magneli, A.

    1986-01-01

    This is the first conference to be arranged within the framework of an agreement on scientific exchange and co-operation between l Academie des Sciences de l Institut de France and the Royal Swedish Academy of Sciences. The responsibility for the scientific program of the conference has been shared between members of the two Academies. The contributions include glimpses of the historical background and broad reviews of the present status of development and of recent work in powder crystallography. Reports are given on a number of studies, basic as well as applied in character, currently conducted in the two countries in a large variety of fields. Prospects of further developments in the area are also presented

  6. Copper-indium-gallium-diselenide nanoparticles synthesized by a solvothermal method for solar cell application

    Directory of Open Access Journals (Sweden)

    Chiou Chuan-Sheng

    2017-01-01

    Full Text Available Chalcopyrite copper-indium-gallium-diselenide (CIGS nanoparticles are useful for photovoltaic applications. In this study, the synthesis of CIGS powder was examined, and the powder was successfully synthesized using a relatively simple and convenient elemental solvothermal route. From the reactions of elemental Cu, In, Se and Ga(NO33 powders in an autoclave with ethylenediamine as a solvent, spherical CIGS nanoparticles, with diameters ranging from 20-40 nm, were obtained using a temperature of 200°C for 36h. The structure, morphology, chemical composition and optical properties of the as-synthesized CIGS were characterized using X-ray diffraction, transmission electron microscopy, selected area electron diffraction, scanning electron microscopy, inductively coupled plasma-mass spectrometry. In this sample, the mole ratio of Cu:In:Ga:Se was equal to 0.89:0.71:0.29:2.01, and the optical band gap was found to be 1.18 eV. The solar cell obtained a power conversion efficiency of 5.62% under standard air mass 1.5 global illumination.

  7. Obtaining zircaloy powder through hydriding

    International Nuclear Information System (INIS)

    Dupim, Ivaldete da Silva; Moreira, Joao M.L.

    2009-01-01

    Zirconium alloys are good options for the metal matrix in dispersion fuels for power reactors due to their low thermal neutron absorption cross-section, good corrosion resistance, good mechanical strength and high thermal conductivity. A necessary step for obtaining such fuels is producing Zr alloy powder for the metal matrix composite material. This article presents results from the Zircaloy-4 hydrogenation tests with the purpose to embrittle the alloy as a first step for comminuting. Several hydrogenation tests were performed and studied through thermogravimetric analysis. They included H 2 pressures of 25 and 50 kPa and temperatures ranging between from 20 to 670 deg C. X-ray diffraction analysis showed in the hydrogenated samples the predominant presence of ZrH 2 and some ZrO 2 . Some kinetics parameters for the Zircaloy-4 hydrogenation reaction were obtained: the time required to reach the equilibrium state at the dwell temperature was about 100 minutes; the hydrogenation rate during the heating process from 20 to 670 deg C was about 21 mg/h, and at constant temperature of 670 deg C, the hydride rate was about 1.15 mg/h. The hydrogenation rate is largest during the heating process and most of it occurs during this period. After hydrogenated, the samples could easily be comminuted indicating that this is a possible technology to obtain Zircaloy powder. The results show that only few minutes of hydrogenation are necessary to reach the hydride levels required for comminuting the Zircaloy. The final hydride stoichiometry was between 2.7 and 2.8 H for each Zr atom in the sample (author)

  8. The synthesis of a high quality, low cost silicon nitride powder by the carbothermal reduction of silica

    International Nuclear Information System (INIS)

    Cochran, G.A.; Conner, C.L.; Eisman, G.A.; Weimer, A.W.; Carroll, D.F.; Dunmead, S.D.; Hwang, C.J.

    1994-01-01

    The development and emergence of silicon nitride in the marketplace depends on the availability of a high quality, low cost powder which meets or exceeds the requirements for the customer's part application. The Dow Chemical Company, funded by the United States Department of Energy Oak Ridge National Laboratory, is engaged in developing a process which will economically synthesize commercial quantities of such a high quality powder. The Dow Chemical Company's approach is based on the carbothermal reduction of silica and has been shown to produce a sub-micron, equi-axed powder with high alpha content (> 95%), low oxygen (< 2%), and minimal carbon and impurities. This paper will review The Dow Chemical Company program and present preliminary results of the synthesis and powder processing efforts. (orig.)

  9. Modeling of microwave heating of metallic powders

    International Nuclear Information System (INIS)

    Buchelnikov, V.D.; Louzguine-Luzgin, D.V.; Anzulevich, A.P.; Bychkov, I.V.; Yoshikawa, N.; Sato, M.; Inoue, A.

    2008-01-01

    As it is known from the experiment that bulk metallic samples reflect microwaves while powdered samples can absorb such a radiation and be heated efficiently. In the present paper we investigate theoretically the mechanisms of penetration of a layer of metallic powder by microwave radiation and microwave heating of such a system

  10. Production and properties of boride powders

    International Nuclear Information System (INIS)

    Klinskaya, N.A.; Koroleva, E.B.; Petrunichev, V.A.

    1990-01-01

    Results of plasma metallization of boride powders 40-80 μ diam. are presented. Peculiarities of changes of granulometric powder composition and of metallic cover on refractory cores were investigated. There are shown size- and compositional cores effects on metallization level of poders and on cover structure

  11. CLAY SOIL STABILISATION USING POWDERED GLASS

    Directory of Open Access Journals (Sweden)

    J. OLUFOWOBI

    2014-10-01

    Full Text Available This paper assesses the stabilizing effect of powdered glass on clay soil. Broken waste glass was collected and ground into powder form suitable for addition to the clay soil in varying proportions namely 1%, 2%, 5%, 10% and 15% along with 15% cement (base by weight of the soil sample throughout. Consequently, the moisture content, specific gravity, particle size distribution and Atterberg limits tests were carried out to classify the soil using the ASSHTO classification system. Based on the results, the soil sample obtained corresponded to Group A-6 soils identified as ‘fair to poor’ soil type in terms of use as drainage and subgrade material. This justified stabilisation of the soil. Thereafter, compaction, California bearing ratio (CBR and direct shear tests were carried out on the soil with and without the addition of the powdered glass. The results showed improvement in the maximum dry density values on addition of the powdered glass and with corresponding gradual increase up to 5% glass powder content after which it started to decrease at 10% and 15% powdered glass content. The highest CBR values of 14.90% and 112.91% were obtained at 5% glass powder content and 5mm penetration for both the unsoaked and soaked treated samples respectively. The maximum cohesion and angle of internal friction values of 17.0 and 15.0 respectively were obtained at 10% glass powder content.

  12. Solving Crystal Structures from Powder Diffraction Data

    DEFF Research Database (Denmark)

    Christensen, A. Nørlund; Lehmann, M. S.; Nielsen, Mogens

    1985-01-01

    High resolution powder data from both neutron and X-ray (synchrotron) sources have been used to estimate the possibility of direct structure determination from powder data. Two known structures were resolved by direct methods with neutron and X-ray data. With synchrotron X-ray data, the measured ...

  13. 30 CFR 56.6901 - Black powder.

    Science.gov (United States)

    2010-07-01

    ... flame; (ii) Within any building in which a fuel-fired or exposed-element electric heater is operating...; and (4) Opened only when the powder is being transferred to a blasthole or another container and only in locations not listed in paragraph (b)(3) of this section. (c) Black powder shall be transferred...

  14. 30 CFR 57.6901 - Black powder.

    Science.gov (United States)

    2010-07-01

    ... feet of any magazine or open flame; (ii) Within any building in which a fuel-fired or exposed-element electric heater is operating; or (iii) In an area where electrical or incandescent-particle sparks could result in powder ignition; and (4) Opened only when the powder is being transferred to a blasthole or...

  15. Hydrothermal synthesis of fine oxide powders

    Indian Academy of Sciences (India)

    Unknown

    Inorganic powders are among the most important factors in many fields of materials such as ceramics, catalysts, medicines, food, etc. There are many papers and books related to powders preparation by many authors (Veale. 1972; Kato and Yamaguchi 1983; Vincenzini 1983;. Brinker et al 1984; Johnson Jr. 1987; Messing ...

  16. Whey powder sterilization by ionizing irradiation

    International Nuclear Information System (INIS)

    Todorovic, M.; Salatic, Z.; Markov, S.

    1988-01-01

    Whey powder was sterilized by gamma waves application. As a source of irridiation isotope 60Co was used in Institute of Nuclear sciences B oris Kidrich , Vincha-Belgrade (Yugoslavia). The applied doses were: a, b, c, d, and e Kgy. The dose d was radappertization. After whey powder irradiation no adverse changes of organoleptic properties were noticed

  17. 21 CFR 73.1646 - Bronze powder.

    Science.gov (United States)

    2010-04-01

    ... percent. Maximum particle size 45µ (95 percent minimum). Aluminum, zinc, tin, and copper content shall be based on the weight of the dried powder after being thoroughly washed with ether. (c) Uses and restrictions. Bronze powder may be safely used in color externally applied drugs, including those intended for...

  18. A breath actuated dry powder inhaler

    NARCIS (Netherlands)

    de Boer, Anne; Frijlink, Henderik W.; Hagedoorn, Paul

    2015-01-01

    A breath actuated dry powder inhaler with a single air circulation chamber for de-agglomeration of entrained powdered medicament using the energy of the inspiratory air stream. The chamber has a substantially polygonal sidewall, a plurality of air supply channels entering the chamber substantially

  19. Process for fabricating mixed-oxide powders

    International Nuclear Information System (INIS)

    Elmaleh, D.; Giraudel, A.

    1975-01-01

    A physical-chemical process for fabricating homogeneous powders suitable for sintering is described. It can be applied to the synthesis of all mixed oxides having mutually compatible and water soluble salts. As a specific example, the fabrication of lead titanate-zirconate powders used to make hot pressed ceramics is described. These ceramics show improved piezoelectric properties [fr

  20. Evaluating the Johanson theory for titanium powder

    CSIR Research Space (South Africa)

    Chikosha, S

    2015-05-01

    Full Text Available . In this study, the Johanson theory was used to determine the rolling parameters of titanium powder. Preliminary results of the nip angle, nip pressures and maximum horizontal pressures of the mill for the powder rolled on a 55mm diameter roll with roll gap sizes...

  1. Slow stress relaxation behavior of cohesive powders

    NARCIS (Netherlands)

    Imole, Olukayode Isaiah; Paulick, Maria; Magnanimo, Vanessa; Morgenmeyer, Martin; Ramaioli, Marco; Chavez Montes, Bruno E.; Kwade, Arno; Luding, Stefan

    2016-01-01

    We present uniaxial (oedometric) compression tests on two cohesive industrially relevant granular materials (cocoa and limestone powder). A comprehensive set of experiments is performed using two devices – the FT4 Powder Rheometer and the custom made lambdameter – in order to investigate the

  2. Synthesis and characterization of powders calcium phosphate for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, D.M.P. de; Prants, W.T.; Camargo, N.H.A.; Gemelli, E., E-mail: daniellapinheiro@gmail.com, E-mail: w_prants@hotmail.com, E-mail: dem2nhac@joinville.udesc.br, E-mail: dma2ec@joinville.udesc.br [Universidade do Estado de Santa Catarina (UDESC), Joinville, SC (Brazil). Centro de Ciencias Tecnologicas

    2009-07-01

    Scientists of different areas research the bioceramics as new materials to substitute parts of the human body. The bioceramics of the calcium phosphate have the advantage present similar chemical composition to the structure of the bony apatite of the human skeleton. In this study, calcium phosphate powder was synthesized chemically using the solution of phosphorus pentoxide (P{sub 2}O{sub 5}) and calcium oxide (CaO) necessary for molar Ca/P =1.67. These works aim the study of different thermal treatments, physics and of the microstructure properties. For characterization the bony matrix were used the techniques of: X-ray diffraction (DRX); Scanning Electronic Microscopy (SEM) and Differential Scanning Calorimetry (DSC). (author)

  3. A Novel Technique for the Synthesis of Nanodiamond Powder

    Directory of Open Access Journals (Sweden)

    Leiming Fang

    2013-01-01

    Full Text Available We developed a novel technique to synthesize nanodiamond powder through the decomposition of graphitic C3N4 under high pressure and high temperature. The nanodiamond obtained by the present method is in an extremely pure form with no sp2 carbon contaminations. Individual nanodiamond grains are very uniform in size and virtually monodispersed single crystals. The grain size can be controlled from less than 1 nm to several hundred nanometers by adjusting the heating temperature (and also potentially by controlling pressure used for the synthesis. The present product requires neither post-surface treatment to remove outer shell made of sp2 carbons nor deglomeration and size classification unlike the case for nanodiamond obtained by the conventional TNT detonation method.

  4. Synthesis and characterization of powders calcium phosphate for biomedical applications

    International Nuclear Information System (INIS)

    Oliveira, D.M.P. de; Prants, W.T.; Camargo, N.H.A.; Gemelli, E.

    2009-01-01

    Scientists of different areas research the bioceramics as new materials to substitute parts of the human body. The bioceramics of the calcium phosphate have the advantage present similar chemical composition to the structure of the bony apatite of the human skeleton. In this study, calcium phosphate powder was synthesized chemically using the solution of phosphorus pentoxide (P 2 O 5 ) and calcium oxide (CaO) necessary for molar Ca/P =1.67. These works aim the study of different thermal treatments, physics and of the microstructure properties. For characterization the bony matrix were used the techniques of: X-ray diffraction (DRX); Scanning Electronic Microscopy (SEM) and Differential Scanning Calorimetry (DSC). (author)

  5. SHS synthesis of Si-SiC composite powders using Mg and reactants from industrial waste

    Science.gov (United States)

    Chanadee, Tawat

    2017-11-01

    Si-SiC composite powders were synthesized by self-propagating high-temperature synthesis (SHS) using reactants of fly ash-based silica, sawdust-based activated carbon, and magnesium. Fly ash-based silica and sawdust-based activated carbon were prepared from coal mining fly ash and Para rubber-wood sawdust, respectively. The work investigated the effects of the synthesis atmosphere (air and Ar) on the phase and morphology of the SHS products. The SHS product was leached by a two-step acid leaching processes, to obtain the Si-SiC composite powder. The SHS product and SHS product after leaching were characterized by X-ray diffractometry, scanning electron microscopy and energy dispersive X-ray spectrometry. The results indicated that the SHS product synthesized in air consisted of Si, SiC, MgO, and intermediate phases (SiO2, Mg, Mg2SiO4, Mg2Si), whereas the SHS product synthesized in Ar consisted of Si, SiC, MgO and a little Mg2SiO4. The SiC content in the leached-SHS product was higher when Ar was used as the synthesis atmosphere. As well as affecting the purity, the synthesis atmospheres also affected the average crystalline sizes of the products. The crystalline size of the product synthesized in Ar was smaller than that of the product synthesized in air. All of the results showed that fly ash and sawdust could be effective waste-material reactants for the synthesis of Si-SiC composite powders.

  6. Sun drying of residual annatto seed powder

    Directory of Open Access Journals (Sweden)

    Dyego da Costa Santos

    2015-01-01

    Full Text Available Residual annatto seeds are waste from bixin extraction in the food, pharmaceutical and cosmetic industries. Most of this by-product is currently discarded; however, the use of these seeds in human foods through the elaboration of powder added to other commercial powders is seen as a viable option. This study aimed at drying of residual annatto powder, with and without the oil layer derived from the industrial extraction of bixin, fitting different mathematical models to experimental data and calculating the effective moisture diffusivity of the samples. Powder containing oil exhibited the shortest drying time, highest drying rate (≈ 5.0 kg kg-1 min-1 and highest effective diffusivity (6.49 × 10-12 m2 s-1. All mathematical models assessed were a suitable representation of the drying kinetics of powders with and without oil, with R2 above 0.99 and root mean square error values lower than 1.0.

  7. Densification behavior of aluminum alloy powder mixed with zirconia powder inclusion under cold compaction

    International Nuclear Information System (INIS)

    Ryu, Hyun Seok; Lee, Sung Chul; Kim, Ki Tae

    2002-01-01

    Densification behavior of composite powders was investigated during cold compaction. Experimental data were obtained for aluminum alloy powder mixed with zirconia powder inclusion under triaxial compression. The cap model with constraint factors was implemented into a finite element program(ABAQUS) to simulate compaction responses of composite powders during cold compaction. Finite element results were compared with experimental data for densification behavior of composite powders under cold isostatic pressing and die compaction. The agreements between experimental data and finite element calculations from the cap model with constraint factors were good

  8. Photocatalytic behaviors and structural characterization of nanocrystalline Fe-doped TiO2 synthesized by mechanical alloying

    International Nuclear Information System (INIS)

    Kim, Dong Hyun; Hong, Hyun Seon; Kim, Sun Jae; Song, Jae Sung; Lee, Kyung Sub

    2004-01-01

    Nanocrystalline Fe-doped TiO 2 powders were synthesized by mechanical alloying (MA) with varying Fe contents from 0 up to 4.8 wt.% to shift the absorption threshold into the visible light region. The photocatalytic feasibility of the Fe-doped TiO 2 powder was evaluated by quantifying the visible light absorption capacity using ultraviolet and visible (UV-Vis) spectroscopy and photoluminescence spectroscopy. Effects of Fe additions on the crystal structures and the morphologies of the Fe-doped powders were also investigated as a function of the doping content using transmission electron microscopy-electron diffraction pattern (TEM-EDP), X-ray diffraction (XRD) and energy dispersive X-ray (EDAX) and X-ray photoelectron spectroscopy (XPS). The UV-Vis study showed that the UV absorption for the Fe-doped powder moved to a longer wavelength (red shift) and the photoefficiency was enhanced. Based on the analysis of the photoluminescence spectra, the red shift was believed to be induced by localizing the dopant level near the valence band of TiO 2 . The UV-Vis absorption depended on the Fe concentration. TEM-EDP and XRD investigations showed that the Fe-doped powder had a rutile phase in which the added Fe atoms were dissolved. The rutile phase was composed of spherical particles and chestnut bur shaped particles, resulting in a larger surface area than the spherical P-25 powder

  9. Characterization of Ni ferrites powders prepared by plasma arc discharge process

    Science.gov (United States)

    Safari, A.; Gheisari, Kh.; Farbod, M.

    2017-01-01

    The aim of this work was to synthesize a single-phase spinel structure from a mixture of zinc, iron and nickel powders by plasma arc discharge method. A mixture of zinc, iron and nickel powders with the appropriate molar ratio was prepared and formed into a cylindrical shape. The synthesis process was performed in air, oxygen and argon atmospheres with the applied arc current of 400 A and pressure of 1 atm. After establishing an arc between the electrodes, the produced powders were collected and their structure and magnetic properties were examined by XRD and VSM, respectively. ZnO as an impurity was appeared in the as-produced powders owing to the high reactivity of zinc atoms, preventing the formation of Ni-Zn ferrite. A pure spinel structure with the highest saturation magnetization (43.8 emu/g) was observed as zinc powders removed completely from the initial mixture. Morphological evaluations using field emission scanning electron microscopy showed that the mean size of fabricated nanoparticles was in the range 100-200 nm and was dependent on the production conditions.

  10. Mössbauer and magnetic studies of nanocrystalline zinc ferrites synthesized by microwave combustion method

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoud, Mohamed, E-mail: mamdouh-2000-2000@yahoo.com [Assiut University, Department of Physics (Egypt); Hassan, Azza Mohamed [Asuite University, Physics Department, Faculty of Sciences (Egypt); Ahmed, Mamdouh Abdel aal [Al Azhar University, Physics Department, Faculty of Science (Egypt); Zhu, Kaixin; Ganeshraja, Ayyakannu Sundaram; Wang, Junhu, E-mail: Wangjh@dicp.ac.cn [Chinese Academy Sciences, Mössbauer Effect Data Center & Laboratory of Catalysts and New Materials for Aerospace, Dalian Institute of Chemical Physics (China)

    2016-12-15

    Zinc ferrite nano-crystals were synthesized by a microwave assisted combustion route with varying the urea to metal nitrates (U/N) molar ratio The process takes only a few minutes to obtain Zinc ferrite powders. The Effect of U/N ratio on the obtained phases, particle size, magnetization and structural properties has been investigated. The specimens were characterized by XRD, Mössbauer and VSM techniques. The sample prepared with urea/metal nitrate ratio of 1/1 was a poorly crystalline phase with very small crystallite size. A second phase is also detected in the sample. The crystallite size increases while the second phase decrease with increasing the urea ratio. The saturation magnetization and coercivity of the as prepared nano-particles changed with the change of the U/N ratio. The powder with the highest U/N ratio showed the presence of an unusually high saturation magnetization of 16 emu/g at room temperature. The crystallinity of the as prepared powder was developed by annealing the samples at 700 {sup ∘}C and 900 {sup ∘}C. Both the saturation magnetization (Ms) and the remnant magnetization (Mr) were found to be highly dependent upon the annealing temperature. Mössbauer studies show magnetic ordering in the powder even at room temperature. The Mössbauer and the magnetic parameters of this fraction are different from the standard values for bulk zinc ferrite.

  11. Synthesis and characterization of bismuth alkaline titanate powders

    Energy Technology Data Exchange (ETDEWEB)

    Torres-Huerta, A.M., E-mail: atorresh@ipn.mx [CICATA-Altamira, Instituto Politecnico Nacional, Km. 14.5 Carretera Tampico Puerto Industrial Altamira, Altamira, Tamps. 89600 (Mexico); Dominguez-Crespo, M.A. [CICATA-Altamira, Instituto Politecnico Nacional, Km. 14.5 Carretera Tampico Puerto Industrial Altamira, Altamira, Tamps. 89600 (Mexico); Hernandez-Perez, M.A. [ESIQIE, Metalurgia, Instituto Politecnico Nacional, Mexico, D. F (Mexico); Garcia-Zaleta, D.S. [CICATA-Altamira, Instituto Politecnico Nacional, Km. 14.5 Carretera Tampico Puerto Industrial Altamira, Altamira, Tamps. 89600 (Mexico); Brachetti-Sibaja, S.B. [CICATA-Altamira, Instituto Politecnico Nacional, Km. 14.5 Carretera Tampico Puerto Industrial Altamira, Altamira, Tamps. 89600 (Mexico); Instituto Tecnologico de Ciudad Madero, Av. 1o. de Mayo esq. Sor Juana Ines de la Cruz s/n Col. Los Mangos C.P.89440 Cd. Madero Tamaulipas (Mexico)

    2011-06-15

    In this work, samples of bismuth alkaline titanate, (K{sub 0.5}Na{sub 0.5}){sub (2-x/2)}Bi{sub (x/6)}TiO{sub 3}, (x = 0.05-0.75) have been prepared by conventional ceramic technique and molten salts. Metal oxides or carbonates powders were used as starting raw materials. The crystalline phase of the synthesized powders was identified by the X-ray diffraction (XRD) and particle morphology was characterized by scanning electron microscopy (SEM). Solid state reaction method was unsuccessful to obtain pellets. From XRD results, a rhombohedral structure was detected and the parameter lattice were estimated to be a = 5.5478 A and {alpha} = 59.48{sup o}. These parameters were used to refine the structure by Rietveld analysis. SEM results showed several morphologies. Apparently, bismuth is promoting the grain growth whose sizes vary from 30 nm to 180 nm It is expected that these materials can be utilized in practical applications as substitutes for lead zirconatetitanate (PZT)-based ceramics.

  12. An analysis of un-dissolved powders of instant powdered soup by using ultrasonographic image

    Science.gov (United States)

    Kawaai, Yukinori; Kato, Kunihito; Yamamoto, Kazuhiko; Kasamatsu, Chinatsu

    2008-11-01

    Nowadays, there are many instant powdered soups around us. When we make instant powdered soup, sometimes we cannot dissolve powders perfectly. Food manufacturers want to improve this problem in order to make better products. Therefore, they have to measure the state and volume of un-dissolved powders. Earlier methods for analyzing removed the un-dissolved powders from the container, the state of the un-dissolved power was changed. Our research using ultrasonographic image can measure the state of un-dissolved powders with no change by taking cross sections of the soup. We then make 3D soup model from these cross sections of soup. Therefore we can observe the inside of soup that we do not have ever seen. We construct accurate 3D model. We can visualize the state and volume of un-dissolved powders with analyzing the 3D soup models.

  13. Corrosion-resistant powder-metallurgy stainless steel powders and compacts therefrom

    International Nuclear Information System (INIS)

    Klar, E.; Ro, D.H.; Whitman, C.I.

    1980-01-01

    Disclosed is a process for improving the corrosion resistance of a stainless steel powder or compact thereof wherein the powder is produced by atomizing a melt of metals in an oxidizing environment whereby the resulting stainless steel powder is surface-enriched in silicon oxides. The process comprises adding an effective proportion of modifier metal to the melt prior to the atomization, the modifier metal selected from the group consisting of tin, aluminum, lead, zinc, magnesium, rare earth metals and like metals capable of enrichment about the surface of the resulting atomized stainless steel powder and effective under reductive sintering conditions in the depletion of the silicon oxides about the surface; and sintering the resulting atomized powder or a compact thereof under reducing conditions, the sintered powder or compact thereof being depleted in the silicon oxides and the corrosion resistance of the powder or compact thereof being improved thereby

  14. Graphene: powder, flakes, ribbons, and sheets.

    Science.gov (United States)

    James, Dustin K; Tour, James M

    2013-10-15

    Graphene's unique physical and electrical properties (high tensile strength, Young's modulus, electron mobility, and thermal conductivity) have led to its nickname of "super carbon." Graphene research involves the study of several different physical forms of the material: powders, flakes, ribbons, and sheets and others not yet named or imagined. Within those forms, graphene can include a single layer, two layers, or ≤10 sheets of sp² carbon atoms. The chemistry and applications available with graphene depend on both the physical form of the graphene and the number of layers in the material. Therefore the available permutations of graphene are numerous, and we will discuss a subset of this work, covering some of our research on the synthesis and use of many of the different physical and layered forms of graphene. Initially, we worked with commercially available graphite, with which we extended diazonium chemistry developed to functionalize single-walled carbon nanotubes to produce graphitic materials. These structures were soluble in common organic solvents and were better dispersed in composites. We developed an improved synthesis of graphene oxide (GO) and explored how the workup protocol for the synthesis of GO can change the electronic structure and chemical functionality of the GO product. We also developed a method to remove graphene layers one-by-one from flakes. These powders and sheets of GO can serve as fluid loss prevention additives in drilling fluids for the oil industry. Graphene nanoribbons (GNRs) combine small width with long length, producing valuable electronic and physical properties. We developed two complementary syntheses of GNRs from multiwalled carbon nanotubes: one simple oxidative method that produces GNRs with some defects and one reductive method that produces GNRs that are less defective and more electrically conductive. These GNRs can be used in low-loss, high permittivity composites, as conductive reinforcement coatings on Kevlar

  15. Studies on magnetic properties of chemically synthesized crystalline calcium ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Debnath, A., E-mail: debnathanimesh@gmail.com [Department of Civil Engineering, National Institute of Technology Agartala, Jirania, West Tripura, 799046 India (India); Bera, A.; Saha, B. [Department of Physics, National Institute of Technology Agartala, Jirania, West Tripura 799046 (India); Chattopadhyay, K. K. [Department of Physics, Jadavpur University, Kolkata 700 032 (India)

    2016-05-23

    Spinel-type ferrites have taken a very important role for modern electronic industry. Most of these ferrites exhibit low-loss dielectric properties, high resistivity, low eddy current and also high temperature ferromagnetism. Calcium ferrite is one such important metal oxide which is environmentally safe, chemically stable, low cost and greatly abundant. This outstanding material of calcium ferrite is synthesized by a simple chemical precipitation method using NaOH as the precipitating agent. Ferric chloride anhydrous (FeCl{sub 3}) and Calcium chloride dihydrate (CaCl{sub 2}.2H{sub 2}O) were used as iron and calcium sources respectively. The samples were heated at 200°C for 8h to obtain homogeneous powder of Calcium ferrite. The powders were characterized by using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Transmission electrical microscopy (TEM), and Fourier transform infrared spectroscopic (FTIR) measurements. The polycrystalline nature of the sample was confirmed by X-ray diffraction study. The magnetic properties of the sample were investigated by vibrating sample magnetometer (VSM) measurements. Magnetization curve of the prepared sample depicts that as synthesized calcium ferrite nanoparticles have saturation magnetic moment of 1.74 emu/g and the coercivity of 35.08 Oe with superparamagnetic behavior. The synthesized calcium ferrite nanoparticles with such magnetic properties will be a candidate material for different applications in electronics and exploring its functionality in the field of recently developing semiconductor device physics and spintronics.

  16. Influence of cooling modes on purity of solid-state synthesized tetracalcium phosphate

    International Nuclear Information System (INIS)

    Guo Dagang; Xu Kewei; Han Yong

    2005-01-01

    Pure tetracalcium phosphate powder (TTCP) was prepared by a solid-state phase reaction at 1500 deg. C. Effects of cooling modes on the synthesizing process of TTCP powder and its thermal behavior at different heating temperatures were investigated by XRD and FTIR. The results show that cooling in dry air tends to promote formation of single phase TTCP, while in situ cooling in furnace results in a mixture of hydroxyapatite (HAP) and CaO. The examination of the thermal behavior of TTCP indicates that there exists a decomposing zone in the range of 500 deg. C-1200 deg. C, in which the high-temperature synthesized TTCP phase is transformed during the subsequent cooling process. This was confirmed by three additional cooling treatment routes that provide significant experimental evidence to the cooling modes effect on the purity of TTCP. The phase transformation course of starting materials heated to elevated temperatures was further studied by TGA-DSC analysis with the aid of XRD and FTIR, in order to fully understand the complicated synthesizing process of TTCP

  17. Studies on magnetic properties of chemically synthesized crystalline calcium ferrite nanoparticles

    International Nuclear Information System (INIS)

    Debnath, A.; Bera, A.; Saha, B.; Chattopadhyay, K. K.

    2016-01-01

    Spinel-type ferrites have taken a very important role for modern electronic industry. Most of these ferrites exhibit low-loss dielectric properties, high resistivity, low eddy current and also high temperature ferromagnetism. Calcium ferrite is one such important metal oxide which is environmentally safe, chemically stable, low cost and greatly abundant. This outstanding material of calcium ferrite is synthesized by a simple chemical precipitation method using NaOH as the precipitating agent. Ferric chloride anhydrous (FeCl_3) and Calcium chloride dihydrate (CaCl_2.2H_2O) were used as iron and calcium sources respectively. The samples were heated at 200°C for 8h to obtain homogeneous powder of Calcium ferrite. The powders were characterized by using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Transmission electrical microscopy (TEM), and Fourier transform infrared spectroscopic (FTIR) measurements. The polycrystalline nature of the sample was confirmed by X-ray diffraction study. The magnetic properties of the sample were investigated by vibrating sample magnetometer (VSM) measurements. Magnetization curve of the prepared sample depicts that as synthesized calcium ferrite nanoparticles have saturation magnetic moment of 1.74 emu/g and the coercivity of 35.08 Oe with superparamagnetic behavior. The synthesized calcium ferrite nanoparticles with such magnetic properties will be a candidate material for different applications in electronics and exploring its functionality in the field of recently developing semiconductor device physics and spintronics.

  18. Gadolinium-doped ceria nanopowders synthesized by urea-based homogeneous co-precipitation (UBHP)

    Energy Technology Data Exchange (ETDEWEB)

    Accardo, G., E-mail: d16605@kist.re.kr [Fuel Cell Research Center, Korea Institute of Science and Technology, Hwarangno 14-gil, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Spiridigliozzi, L. [Department of Civil and Mechanical Engineering, INSTM Research Unit, University of Cassino and Southern Lazio, Via G. Di Biasio 43, 03043 Cassino, FR (Italy); Cioffi, R.; Ferone, C. [Department of Engineering, INSTM Research Unit, University Parthenope of Naples, Centro Direzionale, Is. C4, 80143 Napoli (Italy); Di Bartolomeo, E. [Department of Chemical Science and Technology, University of Rome “Tor Vergata”, Viale della Ricerca Scientifica, 00133 Rome (Italy); Yoon, Sung Pil [Fuel Cell Research Center, Korea Institute of Science and Technology, Hwarangno 14-gil, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Dell’Agli, G. [Department of Civil and Mechanical Engineering, INSTM Research Unit, University of Cassino and Southern Lazio, Via G. Di Biasio 43, 03043 Cassino, FR (Italy)

    2017-02-01

    Gadolinium (10%)-doped ceria was successfully synthesized by using an urea-based co-precipitation method (UBHP). A single fluorite phase was obtained after a low temperature (400 °C) calcination treatment. The resulting powders showed grains of nanometric size with some agglomerations and an overall good sinterability. Pellets were sintered at 1300 and 1500 °C for 3 h. The ionic conductivity was measured by electrochemical impedance spectroscopy measurements and a correlation between electrical properties and microstructure was revealed. The promising conductivity values showed that the synthesized powders are suitable for intermediate temperature solid oxide fuel cells (IT-SOFCs) applications. - Highlights: • Urea-based homogeneous co-precipitation is applied to synthesize nanocrystalline GDC. • Dense GDC samples at different sintering temperatures were characterized. • SEM and TEM revealed a well define microstructure and controlled composition. • Correlation between electrochemical properties by EIS and microstructure was discussed. • UBHP method can be used to prepare high performance GDC electrolytes.

  19. Study on synthesis of ultrafine Cu–Ag core–shell powders with high electrical conductivity

    International Nuclear Information System (INIS)

    Peng Yuhsien; Yang Chihhao; Chen Kuanting; Popuri, Srinivasa R.; Lee, Ching-Hwa; Tang, Bo-Shin

    2012-01-01

    Highlights: ► This synthesis method is relatively facile, novel and eco-friendly. ► Toxic agents were not used for chelating agent, reductant or dispersant in our method. ► The reaction can under room temperature for energy saving purpose. ► Cu–Ag core–shell powders with homogeneous cover-silver layer. ► The resistivity of Cu–Ag core–shell powders has the same value as the pure silver. - Abstract: Cu–Ag composite powders with high electrical conductivity were synthesized by electroless plating of silver sulfate, copper powders with eco-friendly sodium citrate as reducing agent, dispersant and chelating agent in an aqueous system. The influences of sodium citrate/Ag ratio on Ag coatings of Cu powders were investigated. Ag was formed a dense coating on the surface of Cu powders at a molar ratio of sodium citrate/Ag = 0.07/1. SEM showed an uniformity of Ag coatings on Cu powders. SEM-EDX also revealed that Cu cores were covered by Ag shells on the whole. The surface composition analysis by XPS indicated that without Cu or Ag atoms in the surface were oxidized. The resistivity measurements of Cu–Ag paste shows that they have closer resistivity as the pure silver paste's after 250 °C for 30 min heat-treatment (2.55 × 10 −4 Ω cm) and 350 °C for 30 min heat-treatment (1.425 × 10 −4 Ω cm).

  20. Simple process to fabricate nitride alloy powders

    International Nuclear Information System (INIS)

    Yang, Jae Ho; Kim, Dong-Joo; Kim, Keon Sik; Rhee, Young Woo; Oh, Jang-Soo; Kim, Jong Hun; Koo, Yang Hyun

    2013-01-01

    Uranium mono-nitride (UN) is considered as a fuel material [1] for accident-tolerant fuel to compensate for the loss of fissile fuel material caused by adopting a thickened cladding such as SiC composites. Uranium nitride powders can be fabricated by a carbothermic reduction of the oxide powders, or the nitriding of metal uranium. Among them, a direct nitriding process of metal is more attractive because it has advantages in the mass production of high-purity powders and the reusing of expensive 15 N 2 gas. However, since metal uranium is usually fabricated in the form of bulk ingots, it has a drawback in the fabrication of fine powders. The Korea Atomic Energy Research Institute (KAERI) has a centrifugal atomisation technique to fabricate uranium and uranium alloy powders. In this study, a simple reaction method was tested to fabricate nitride fuel powders directly from uranium metal alloy powders. Spherical powder and flake of uranium metal alloys were fabricated using a centrifugal atomisation method. The nitride powders were obtained by thermal treating the metal particles under nitrogen containing gas. The phase and morphology evolutions of powders were investigated during the nitriding process. A phase analysis of nitride powders was also part of the present work. KAERI has developed the centrifugal rotating disk atomisation process to fabricate spherical uranium metal alloy powders which are used as advanced fuel materials for research reactors. The rotating disk atomisation system involves the tasks of melting, atomising, and collecting. A nozzle in the bottom of melting crucible introduces melt at the center of a spinning disk. The centrifugal force carries the melt to the edge of the disk and throws the melt off the edge. Size and shape of droplets can be controlled by changing the nozzle size, the disk diameter and disk speed independently or simultaneously. By adjusting the processing parameters of the centrifugal atomiser, a spherical and flake shape

  1. Preparation and electrochemical characterization of size controlled SnO2-RuO2 composite powder for monolithic hybrid battery

    International Nuclear Information System (INIS)

    Jeon, Young-Ah; No, Kwang-Soo; Choi, Sun Hee; Ahn, Jae pyong; Yoon, Young Soo

    2004-01-01

    Tin oxide (SnO 2 ) powders with a particle size of ∼20 nm were synthesized by a gas condensation method. Ruthenium oxide was loaded by an incipient-wetness method, in which an aqueous solution of RuCl 3 was added to the manufactured SnO 2 powder in an amount that was just sufficient to wet completely the powder. And then, the resulting solution was obtained after freeze-drying to synthesis the smallest particle. The as-synthesized SnO 2 powder with 1.5 wt.% ruthenium oxide (RuO 2 ) exhibited well-developed facets and had a very uniform particle size. The first discharge capacity was lower than comparing to commercial powder because of forming the second phase, but showed good cyclability. A maximum specific electrode capacitance of ∼20 F/g and a maximum specific power of ∼80 W/kg were achieved by manufactured SnO 2 with 1.5 wt.% RuO 2 . This result indicated that the synthesized SnO 2 -RuO 2 composite powder of nano-size scale is candidate for use in fabricating monolithic hybrid batteries using suitable electrolyte as well

  2. Powder metallurgy development at SRL

    International Nuclear Information System (INIS)

    Peacock, H.B.

    1993-01-01

    The Savannah River Laboratory (SRL) is developing a powder metallurgy (P/M) process for manufacturing reactor-grade fuel tubes containing high wt % U 3 O 8 -Al cores clad with 8001 aluminum. The P/M cores are made by isostatic compaction. They are assembled in billets, outgassed, and hot-extruded using conventional coextrusion techniques. Cores have been compacted with up to 100% U3O 8 and tubes extruded with 80 wt % oxide cores. Irradiation tests have been made using P/M core tubes in the Savannah River reactors. These tubes contained U 3 O 8 concentrations up to 59 wt % and no significant swelling or blistering occurred. The tubes were irradiated to ∼ 40% burnup or 1.6x10 21 fissions/cc of core. This report discusses both small-scale and production tests for high-density P/M fuel development. The purpose of the P/M development program at SRL is to: determine the maximum U 3 O 8 content that can be fabricated into thin wall tubes, irradiate high-density tubes to high burnup and assess irradiation and dimensional stability, continue metal forming studies for extrusion and drawing, and evaluate hydrostatic extrusion and hydrostatically assisted drawing of P/M core tubes. Experimental results of testing the fuel assemblies performance so far indicate that: cores containing fine (-325 mesh) U 3 O 8 and aluminum powders can be made practically free of high-density areas using the outlined P/M pre blending and sieving techniques. U 3 O 8 -Al cores can be isostatically compacted with up to 100 wt U 3 O 8 and tubes successfully extruded with up to 80 wt oxide; fission gas blistering of U 3 O 8 -Al P/M tubes as indicated by the blister tests is a function of fissions/cc of U 3 O 8 in the core; Decreasing the fission density of oxide increases the threshold temperature for blister formation; U 3 O 8 -Al P/M fuel tubes with up to 59 wt U 3 O 8 have been successfully irradiated in SRP reactor to 1.6 x 10 21 fissions/cc of core or 7 x 10 20 fissions/cc of U 3 O 8 small

  3. Bias Voltage-Dependent Impedance Spectroscopy Analysis of Hydrothermally Synthesized ZnS Nanoparticles

    Science.gov (United States)

    Dey, Arka; Dhar, Joydeep; Sil, Sayantan; Jana, Rajkumar; Ray, Partha Pratim

    2018-04-01

    In this report, bias voltage-dependent dielectric and electron transport properties of ZnS nanoparticles were discussed. ZnS nanoparticles were synthesized by introducing a modified hydrothermal process. The powder XRD pattern indicates the phase purity, and field emission scanning electron microscope image demonstrates the morphology of the synthesized sample. The optical band gap energy (E g = 4.2 eV) from UV measurement explores semiconductor behavior of the synthesized material. The electrical properties were performed at room temperature using complex impedance spectroscopy (CIS) technique as a function of frequency (40 Hz-10 MHz) under different forward dc bias voltages (0-1 V). The CIS analysis demonstrates the contribution of bulk resistance in conduction mechanism and its dependency on forward dc bias voltages. The imaginary part of the impedance versus frequency curve exhibits the existence of relaxation peak which shifts with increasing dc forward bias voltages. The dc bias voltage-dependent ac and dc conductivity of the synthesized ZnS was studied on thin film structure. A possible hopping mechanism for electrical transport processes in the system was investigated. Finally, it is worth to mention that this analysis of bias voltage-dependent dielectric and transport properties of as-synthesized ZnS showed excellent properties for emerging energy applications.

  4. Microanalysis on CuInSe2 compound synthesized by mechanochemical processing

    International Nuclear Information System (INIS)

    Wu Sumei; Xue Yuzhi; Zhang Zhihua

    2010-01-01

    CuInSe 2 (CIS) compound has been synthesized by mechanochemical processing (MCP) with different process parameters. The effect of milling time and different molar ratios of Cu:In:Se was investigated. The obtained materials were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) for evaluating their crystal structure, grain size, morphology and composition. Field emission transmission electron microscopy (FETEM) was used to detect the smog particles produced during the milling. The results revealed that the obtained powder was chalcopyrite CuInSe 2 and the particle size was smaller than 5 μm after milling for 60 min. The EDS analysis indicated that the smog was volatile selenium. The composition of the products deviated from those of starting materials after MCP. The mechanism about mechanically induced self-propagating reaction which occurred during milling copper, indium and selenium powders was also discussed.

  5. Impact of physical and chemical parameters on the hydroxyapatite nanopowder synthesized by chemical precipitation method

    Science.gov (United States)

    Thu Trang Pham, Thi; Phuong Nguyen, Thu; Pham, Thi Nam; Phuong Vu, Thi; Tran, Dai Lam; Thai, Hoang; Thanh Dinh, Thi Mai

    2013-09-01

    In this paper, the synthesis of hydroxyapatite (HAp) nanopowder was studied by chemical precipitation method at different values of reaction temperature, settling time, Ca/P ratio, calcination temperature, (NH4)2HPO4 addition rate, initial concentration of Ca(NO3)2 and (NH4)2HPO4. Analysis results of properties, morphology, structure of HAp powder from infrared (IR) spectra, x-ray diffraction (XRD), energy dispersive x-ray (EDX) spectra and scanning electron microscopy (SEM) indicated that the synthesized HAp powder had cylinder crystal shape with size less than 100 nm, single-phase structure. The variation of the synthesis conditions did not affect the morphology but affected the size of HAp crystals.

  6. Nickel oxide/hydroxide nanoplatelets synthesized by chemical precipitation for electrochemical capacitors

    International Nuclear Information System (INIS)

    Wu, M.-S.; Hsieh, H.-H.

    2008-01-01

    Nickel hydroxide powder prepared by directly chemical precipitation method at room temperature has a nanoplatelet-like morphology and could be converted into nickel oxide at annealing temperature higher than 300 deg. C, confirmed by the thermal gravimetric analysis and X-ray diffraction. Annealing temperature influences significantly both the electrical conductivity and the specific surface area of nickel oxide/hydroxide powder, and consequently determines the capacitor behavior. Electrochemical capacitive behavior of the synthesized nickel hydroxide/oxide film is investigated by cyclic voltammetry and electrochemical impedance spectroscope methods. After 300 deg. C annealing, the highest specific capacitance of 108 F g -1 is obtained at scan rate of 10 mV s -1 . When annealing temperature is lower than 300 deg. C, the electrical conductivity of nickel hydroxide dominates primarily the capacitive behavior. When annealing temperature is higher than 300 deg. C, both electrical conductivity and specific surface area of the nickel oxide dominate the capacitive behavior

  7. Method to synthesize metal chalcogenide monolayer nanomaterials

    Science.gov (United States)

    Hernandez-Sanchez, Bernadette A.; Boyle, Timothy J.

    2016-12-13

    Metal chalcogenide monolayer nanomaterials can be synthesized from metal alkoxide precursors by solution precipitation or solvothermal processing. The synthesis routes are more scalable, less complex and easier to implement than other synthesis routes.

  8. nanoparticles synthesized by citrate precursor m

    African Journals Online (AJOL)

    user

    (M=Co, Cu) nanoparticles synthesized by citrate precursor method ... The structural characterization was carried out using an X-ray Diffractometer (Rikagu Miniflex, Japan) ..... His current area of interest includes magnetic nanomaterials.

  9. Syntheses, molecular and crystalline architectures, and ...

    Indian Academy of Sciences (India)

    Syntheses, molecular and crystalline architectures, and luminescence behaviour of terephthalate bridged heptacoordinated dinuclear lead(II) complexes containing a pentadentate N-donor Schiff base. SUBHASIS ROYa, SOMNATH CHOUBEYa, SUMITAVA KHANa, KISHALAY BHARa,. PARTHA MITRAb and BARINDRA ...

  10. Synthese en chemotherapeutisch onderzoek van sulfanilamidopyrimidinen

    NARCIS (Netherlands)

    Grevenstuk, Anton Bernard

    1942-01-01

    In order to investigate the influence of substitution in the pyrimidine nucleous on the activity of the three isomeric sulfanilamidopyrimidines (2, 5 and 6), a number of substituted sulfanilamidopyrimidines were synthesized and tested on chemotherapeutic activity. ... Zie: Summary

  11. Hygroscopic behavior of lyophilized acerola pulp powder

    Directory of Open Access Journals (Sweden)

    Luciana C. Ribeiro

    2016-03-01

    Full Text Available ABSTRACT Powder products are characterized by their practicality and long life. However, fruit powders have high hygroscopicity and tend to agglomerate due to its hydrophilic nature. The isotherms of equilibrium moisture content apply to the study of dehydrated food preservation potential. Acerola is a nutritionally rich fruit, with great economic and industrial potential. The objective of this study was to analyse acerola powder adsorption isotherms obtained by lyophilization and characterize the powder obtained from lyophilized acerola pulp. Analysis of hygroscopicity, solubility and degree of caking were performed. Isotherms were represented by the mathematical models of GAB, BET, Henderson and Oswin, at temperatures of 25, 35 and 45 °C. According to the results, the obtained powder showed hygroscopicity of 5.96 g of absorbed water 100g-1 of solids, solubility of 95.08% and caking of 14.12%. The BET model showed the best fit to the adsorption isotherms of the acerola pulp powder obtained by lyophilization. The obtained isotherm was of type III, with a "J" shape. There was an inversion of the effect of temperature on the isotherms of acerola powders.

  12. Crushing method for nuclear fuel powder

    International Nuclear Information System (INIS)

    Hasegawa, Shin-ichi; Tsuchiya, Haruo.

    1997-01-01

    A crushing medium is contained in mill pots disposed at the circumferential periphery of a main axis. The diameter of each mill pot is determined such that powdery nuclear fuels containing aggregated powders and ground and mixed powders do not reach criticality. A plurality of mill pots are revolved in the direction of the main axis while each pots rotating on its axis. Powdery nuclear fuels containing aggregated powders are conveyed to a supply portion of the moll pot, and an inert gas is supplied to the supply portion. The powdery nuclear fuels are supplied from the supply portion to the inside of the mill pots, and the powdery nuclear fuels containing aggregated powders are crushed by centrifugal force caused by the rotation and the revolving of the mill pots by means of the crushing medium. UO 2 powder in uranium oxide fuels can be crushed continuously. PuO 2 powder and UO 2 powder in MOX fuels can be crushed and mixed continuously. (I.N.)

  13. CAMAC programmable-control frequency synthesizer

    International Nuclear Information System (INIS)

    Yumaguzin, T.Kh.; Vyazovkin, D.E.; Nazirov, Eh.P.; Tuktarov, R.F.

    1989-01-01

    Synthesizer allows to set frequency with 0.015% accuracy and to scan it with variable step. Frequency controlled divider with further summing-up of divided frequency with fundamental one is used in synthesizer, and it has allowed to use digit of the input code and to obtain 3-4 MHz frequency range. Variation of operation flowsheet in the other frequency range is possible. K-155 and K-531 series microcircuits were used during development

  14. Operational Design that Synthesizes Art and Science

    Science.gov (United States)

    2011-05-04

    FINAL 3. DATES COVERED (From - To) Feb - May 2011 4. TITLE AND SUBTITLE OPERATIONAL DESIGN THAT SYNTHESIZES ART AND SCIENCE 5a...TITLE AND SUBTITLE Operational Design That Synthesizes Art And Science 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR...proponents of EBO view warfare as only a science and not a combination of art and science . 9 Another main point of contention centered on the term

  15. Raman assisted lightwave synthesized frequency sweeper

    DEFF Research Database (Denmark)

    Pedersen, Anders Tegtmeier; Rottwitt, Karsten

    2010-01-01

    We present a Lightwave Synthesized Frequency Sweeper comprising a Raman amplifier for loss compensation. The generated pulse train contains 123 pulses and has a flat signal level as well as a low noise level.......We present a Lightwave Synthesized Frequency Sweeper comprising a Raman amplifier for loss compensation. The generated pulse train contains 123 pulses and has a flat signal level as well as a low noise level....

  16. Atomic layer deposition of titanium oxide films on As-synthesized magnetic Ni particles: Magnetic and safety properties

    Energy Technology Data Exchange (ETDEWEB)

    Uudeküll, Peep, E-mail: peep.uudekull@ut.ee [Institute of Physics, University of Tartu, W. Ostwaldi Str.1, 50411 Tartu (Estonia); Kozlova, Jekaterina; Mändar, Hugo [Institute of Physics, University of Tartu, W. Ostwaldi Str.1, 50411 Tartu (Estonia); Link, Joosep [Laboratory of Chemical Physics, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Sihtmäe, Mariliis [Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Käosaar, Sandra [Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Faculty of Chemical and Materials Technology, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia); Blinova, Irina; Kasemets, Kaja; Kahru, Anne [Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Stern, Raivo [Laboratory of Chemical Physics, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Tätte, Tanel [Institute of Physics, University of Tartu, W. Ostwaldi Str.1, 50411 Tartu (Estonia); Kukli, Kaupo [Institute of Physics, University of Tartu, W. Ostwaldi Str.1, 50411 Tartu (Estonia); University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland); Tamm, Aile [Institute of Physics, University of Tartu, W. Ostwaldi Str.1, 50411 Tartu (Estonia)

    2017-05-01

    Spherical nickel particles with size in the range of 100–400 nm were synthesized by non-aqueous liquid phase benzyl alcohol method. Being developed for magnetically guided biomedical applications, the particles were coated by conformal and antimicrobial thin titanium oxide films by atomic layer deposition. The particles retained their size and crystal structure after the deposition of oxide films. The sensitivity of the coated particles to external magnetic fields was increased compared to that of the uncoated powder. Preliminary toxicological investigations on microbial cells and small aquatic crustaceans revealed non-toxic nature of the synthesized particles.

  17. Atomic layer deposition of titanium oxide films on As-synthesized magnetic Ni particles: Magnetic and safety properties

    International Nuclear Information System (INIS)

    Uudeküll, Peep; Kozlova, Jekaterina; Mändar, Hugo; Link, Joosep; Sihtmäe, Mariliis; Käosaar, Sandra; Blinova, Irina; Kasemets, Kaja; Kahru, Anne; Stern, Raivo; Tätte, Tanel; Kukli, Kaupo; Tamm, Aile

    2017-01-01

    Spherical nickel particles with size in the range of 100–400 nm were synthesized by non-aqueous liquid phase benzyl alcohol method. Being developed for magnetically guided biomedical applications, the particles were coated by conformal and antimicrobial thin titanium oxide films by atomic layer deposition. The particles retained their size and crystal structure after the deposition of oxide films. The sensitivity of the coated particles to external magnetic fields was increased compared to that of the uncoated powder. Preliminary toxicological investigations on microbial cells and small aquatic crustaceans revealed non-toxic nature of the synthesized particles.

  18. Magnetic Properties and Structural Characteristics of BaFe12O19 Hexaferrites Synthesized by the Zol-Gel Combustion

    Science.gov (United States)

    Zhuravlev, V. A.; Itin, V. I.; Minin, R. V.; Lopushnyak, Yu. M.; Velikanov, D. A.

    2018-03-01

    The phase structure, structural parameters, and basic magnetic characteristics of BaFe12O19 hexaferrites prepared by the zol-gel combustion method with subsequent annealing at a temperature of 850°C for 6 h are investigated. The influence of the organic fuel type on the properties of synthesized materials is analyzed. Values of the saturation magnetization and the anisotropy field are determined. It is established that they depend on the organic fuel type. It is shown that powders synthesized with citric acid used as a fuel have the largest particle sizes and the highest saturation magnetization.

  19. Study On Precipitation Of UO2 Ex-AUC Powder. Part I: Precipitation Of AUC By (NH4)2CO3 From Uranyl Fluoride Solution

    International Nuclear Information System (INIS)

    Nguyen Trong Hung; Le Ba Thuan; Do Van Khoai; Nguyen Thanh Thuy; Nguyen Van Tung

    2011-01-01

    In this paper, Ammonium Uranyl Carbonate (AUC) powders were prepared by precipitation method in solution. UO 2 F 2 /HF, ammonium carbonate (AC), and ammonium hydroxide solution were used as precursors for precipitation. The influence of C/U ratio (mol/mol), AC concentration (g/L), reaction temperature ( o C), on characteristics of AUC powders was also investigated. Then, the synthesized AUC powders were analyzed (to define) phase composition (X-ray), fluorine content, morphology (by SEM), and specific surface area (BET). (author)

  20. Biocompatible nanocrystalline natural bonelike carbonated hydroxyapatite synthesized by mechanical alloying in a record minimum time

    Energy Technology Data Exchange (ETDEWEB)

    Lala, S. [Materials Science Division, Department of Physics, The University of Burdwan, Golapbag, Burdwan-713104, West Bengal (India); Brahmachari, S.; Das, P.K. [Department of Biological Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700 032 (India); Das, D. [UGC-DAE Consortium for Scientific Research, Kolkata-700098 (India); Kar, T. [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032 (India); Pradhan, S.K., E-mail: skp_bu@yahoo.com [Materials Science Division, Department of Physics, The University of Burdwan, Golapbag, Burdwan-713104, West Bengal (India)

    2014-09-01

    Single phase nanocrystalline biocompatible A-type carbonated hydroxyapatite (A-cHAp) powder has been synthesized by mechanical alloying the stoichiometric mixture of CaCO{sub 3} and CaHPO{sub 4}.2H{sub 2}O powders in open air at room temperature within 2 h of milling. The A-type carbonation in HAp is confirmed by FTIR analysis. Structural and microstructure parameters of as-milled powders are obtained from both Rietveld's powder structure refinement analysis and transmission electron microscopy. Size and lattice strain of nanocrystalline HAp particles are found to be anisotropic in nature. Mechanical alloying causes amorphization of a part of crystalline A-cHAp which is analogous to native bone mineral. Some primary bond lengths of as-milled samples are critically measured. MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay test reveals high percentage of cell viability and hence confirms the biocompatibility of the sample. The overall results indicate that the processed A-cHAp has a chemical composition very close to that of biological apatite. - Graphical abstract: Biocompatible A-Type Carbonated Hydroxyapatite (A-cHAp) has been synthesized by mechanical alloying in polycrystalline form within 2 h of milling. The shape and position of CO channel have been shown. - Highlights: • A-cHAp phase is completed within 2 h of milling. • FTIR analysis confirms A-type carbonation in HAp. • Amorphization of a part of crystalline A-cHAp. • Particle size and strain are anaisotropic in nature. • High cell viability under MTT assay.

  1. Producing tantalum or columbium powder

    International Nuclear Information System (INIS)

    Rerat, C.F.

    1979-01-01

    A process is described for the production of tantalum or columbium powder with a high yield within a desired range of particle sizes. A molten salt bath of a double salt comprising either an alkali metal tantalum fluoride or an alkali metal columbium fluoride and a relatively large amount of alkali metal halide diluent salt to act as a heat sink is initially maintained at a temperature a little above the liquidus temperature of the salt mixture. A liquid alkali metal at a comparatively low temperature is added to the continuously stirred bath at a high mass flow rate, and reduces the double salt, producing tantalum or columbium. The reaction is exothermic and causes the temperature to rise rapidly to a desired final reaction temperature within the range 760 to 1000 0 . The liquid alkali metal is thereafter fed at a high mass flow rate to complete the reaction quickly at the final reaction temperature. Forced cooling at a heat extraction rate not less than 42 kilojoules/min./kg. of double salt is used during at least a portion of the reaction cycle at a rate sufficient to maintain the final reaction temperature within a desired range. (author)

  2. Powder metallurgy development at SRL

    International Nuclear Information System (INIS)

    Peacock, H.B.

    1978-01-01

    Fuel for Savannah River Plant (SRP) reactors consists of extruded tubes with aluminum--uranium alloy cores clad with 8001 aluminum. The 235 U in the fuel is periodically recovered and recycled in new fuel assemblies. The buildup of 236 U in the enriched uranium requires increased total uranium contents to maintain reactivity in existing assembly designs. High level waste production from these tubes is proportional to the aluminum content; therefore, appreciable radioactive waste reductions result from lower aluminum--uranium ratios and thinner clad tubes. The casting process now used for fuel cores is limited to below 40 wt % U because of the reduced fabricability of high uranium alloys. To increase tube loading and reduce aluminum, the U 3 O 8 -Al powder metallurgy (P/M) process for fuel tubes is under development. Several fabricaion and irradiaion tests have been made using production conditions. Both small scale and production tests carried out at SRL for high-density P/M fuel development are discussed

  3. Powder metallurgy development at SRL

    International Nuclear Information System (INIS)

    Peacock, H.B.

    1993-01-01

    The Savannah River Laboratory (SRL) is developing a powder metallury (P/M) process for manufacturing reactor-grade fuel tubes containing high wt % U 3 O 8 -Al cores clad with 8001 aluminum. The P/M cores are made by isostatic compaction. They are assembled in billets, outgassed, and hot-extruded using conventional coextrusion techniques. Cores have been compacted with up to 100% U 3 O 8 and tubes extruded with 80 wt % oxide cores. Irradiation tests have been made using P/M core tubes in the Savannah River reactors. These tubes contained U 3 O 8 concentrations up to 59 wt % and no significant swelling or blistering occurred. The tubes were irradiated to ∼40% burnup or 1.6x10 21 fissions/cc of core. This report discusses both small-scale and production tests for high- density P/M fuel development. The purpose of the P/M development program at SRL is to: (1) determine the maximum U 3 O 8 content that can be fabricated into thin wall tubes, (2) irradiate high-density tubes to high burnup and assess irradiation and dimensional stability, (3) continue metal forming studies for extrusion and drawing, and (4) evaluate hydrostatic extrusion and hydrostatically assisted drawing of P/M core tubes

  4. Optically stimulated luminescence of ZnO obtained by thermal treatment of ZnS chemically synthesized

    International Nuclear Information System (INIS)

    Cruz V, C.; Burruel I, S.E.; Orante B, V.R.; Grijalva M, H.; Perez S, R.; Bernal, R.

    2005-01-01

    In this work, we report the optically stimulated luminescence (OSL) dosimetry of new nano phosphors of ZnO obtained by thermal annealing of chemically synthesized ZnS powder. The synthesized ZnS nano powder was compressed in order to form pellet shaped pellets, which were afterwards subjected to a thermal annealing at 700 C during 24 h under air atmosphere. X-ray diffraction (XRD) patterns and energy-disperse X-ray Spectrometry (EDS) analyses confirmed the transformation of ZnS to ZnO. Samples were exposed to several doses of beta radiation up to 600 Gy, and the optically stimulated luminescence with 470 nm wavelength light was recorded as a function of dose. The intensity of the OSL signal increases by increasing dose, for what it is concluded that these new phosphor materials are suitable to be used in optically stimulated luminescence dosimetry. (Author)

  5. Use of whey powder and skim milk powder for the production of fermented cream

    Directory of Open Access Journals (Sweden)

    Ceren AKAL

    2016-01-01

    Full Text Available Abstract This study is about the production of fermented cream samples having 18% fat by addition of starter cultures. In order to partialy increase non-fat solid content of fermented cream samples, skim milk powder and demineralized whey powder in two different rates (50% and 70% were used. Samples were analyzed for changes in their biochemical and physicochemical properties (total solid, ash, fat, titratable acidity, pH value, total nitrogen, viscosity, tyrosine, acid number, peroxide and diacetyl values during 29-day of storage period. Samples tested consisted of 7 different groups; control group (without adding any powder, skim milk powder, 50% demineralized whey powder and 70% demineralized whey powder samples were in two different addition rate (2% and 4%. Also samples were analyzed for sensory properties. According to the results obtained, the addition of milk powder products affected titratable acidity and tyrosine values of fermented cream samples. Although powder addition and/or storage period didn’t cause significant variations in total solid, ash, fat, pH value, viscosity, acid number, peroxide, tyrosine and diacetyl values; sensory properties of fermented cream samples were influenced by both powder addition and storage period. Fermented cream containing 2% skim milk powder gets the top score of sensory evaluation among the samples.

  6. Radiotreated cocoa powder for frozen elaboration

    International Nuclear Information System (INIS)

    Rodriguez Jorge, M.; Alvarez Gil, M.; Prieto Miranda, E.; Morales Valladares, M.

    1995-01-01

    The aim of the present papers is to study the possibilities of 2.0 kGy gamma radiotreated cocoa powder to be used in the elaboration of powder mixture for the preparation of chocolate frozen. Three industrial productions were carried out. Microbiological and organoleptic evaluations of the final product were performed. The results showed that the use of radurized cocoa powder in the frozen elaboration is feasible. A good hygienic quality of this product was obtained and no organoleptic alterations were detected [es

  7. Preparation of potassium-reduced tantalum powders

    International Nuclear Information System (INIS)

    Kolosov, V.N.; Miroshnichenko, M.N.; Orlov, V.M.; Prokhorova, T.Yu.

    2005-01-01

    Characteristics of tantalum powders prepared by reduction of molten potassium heptafluorotantalate with liquid potassium are studied in a temperature range of 750 - 850 deg C using potassium chloride as a flux at a ratio of K 2 TaF 7 : KCl = 1, 2, and 3. The use of potassium as a reducing agent facilitates washing of tantalum powders for impurity salt removal, reduces sodium content and leakage currents in the anodes. As compared to sodium process, the potassium reduction results in a high yield of sponge material, a decrease in the specific surface area and yield of tantalum powder suitable for manufacture of capacitor anodes [ru

  8. Powder metallurgy techniques in nuclear technology

    International Nuclear Information System (INIS)

    Mardon, P.G.

    1983-01-01

    The nuclear application of conventional powder metallurgy routes is centred on the fabrication of ceramic fuels. The stringent demands in terms of product performance required by the nuclear industry militate against the use of conventional powder metallurgy to produce metallic components such as the fuel cladding. However, the techniques developed in powder metallurgy find widespread application throughout nuclear technology. Illustrations of the use of these techniques are given in the fields of absorber materials, ceramic cladding materials, oxide fuels, cermet fuels, and the disposal of highly active waste. (author)

  9. Tungsten and tungsten alloys by powder metallurgy

    International Nuclear Information System (INIS)

    Belhadjhamida, A.; German, R.M.

    1991-01-01

    Tungsten has a historical link with powder metallurgy and there is continued progress in expanding the available compositions and processing options. This paper starts with an introduction to the history of tungsten powder metallurgy and use this as a basis for analyzing some of the current trends. The literature base in tungsten processing is expanding and includes new alloys, microstructures, and processing routes. A few examples will be emphasize here to produce a frame work for this program, including description of sintering mechanisms for tungsten, liquid phase sintering advances, hot consolidation fundamentals, and options for complex shaping using powder injection modeling. For this base, subsequent presentations will expand on these fundamental advances

  10. Net shape powder processing of aluminium

    International Nuclear Information System (INIS)

    Schaffer, G.B.

    2000-01-01

    The increasing interest in light weight materials coupled to the need for cost-effective processing have combined to create a significant opportunity for aluminium powder metallurgy. Net shape processing of aluminium using the classical press-and-sinter powder metallurgy technique is a unique and important metal-forming method which is cost effective in producing complex parts at, or very close to, final dimensions. This paper provides an overview of the net shape powder processing of aluminium. Current research is critically reviewed and the future potential is briefly considered

  11. Powder densification maps in Selective Laser Sintering

    International Nuclear Information System (INIS)

    Bourell, D.; Wohlert, M.; Harlan, N.; Beaman, J.; Das, S.

    2002-01-01

    Selective Laser Sintering (SLS) is a manufacturing process in which a part is produced without the need for part-specific tooling. It competes effectively with other manufacturing processes when part geometry is complex and the production run is not large. Traditionally, this was limited to prototype production, although tooling applications are now appearing. This paper describes several applications of powder densification maps to advance solutions in direct SLS of metallic and ceramic powders. Time-dependent plasticity issues arise in pre-processing of powder to make it suitable for SLS and in post-processing of SLS parts to obtain desired density. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

  12. Plasma metallization of refractory carbide powders

    International Nuclear Information System (INIS)

    Koroleva, E.B.; Klinskaya, N.A.; Rybalko, O.F.; Ugol'nikova, T.A.

    1986-01-01

    The effect of treatment conditions in plasma on properties of produced metallized powders of titanium, tungsten and chromium carbides with the main particle size of 40-80 μm is considered. It is shown that plasma treatment permits to produce metallized powders of carbide materials with the 40-80 μm particle size. The degree of metallization, spheroidization, chemical and phase composition of metallized carbide powders are controlled by dispersivity of the treated material, concentration of a metal component in the treated mixtures, rate of plasma flow and preliminary spheroidization procedure

  13. A comparative approach to synthesis and sintering of alumina/yttria nanocomposite powders using different precipitants

    Energy Technology Data Exchange (ETDEWEB)

    Kafili, G. [Department of Nanotechnology Engineering, Faculty of Advanced Sciences and Technologies, University of Isfahan, Isfahan, 81746-73441 (Iran, Islamic Republic of); Movahedi, B., E-mail: b.movahedi@ast.ui.ac.ir [Department of Nanotechnology Engineering, Faculty of Advanced Sciences and Technologies, University of Isfahan, Isfahan, 81746-73441 (Iran, Islamic Republic of); Milani, M. [Faculty of Advanced Materials and Renewable Energy Research Center, Tehran (Iran, Islamic Republic of)

    2016-11-01

    Alumina/yttria nanocomposite powder as an yttrium aluminum garnet (YAG) precursor was synthesized via partial wet route using urea and ammonium hydrogen carbonate (AHC) as precipitants, respectively. The products were characterized using X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and energy dispersive spectroscopy. The use of urea produced very tiny spherical Y-compounds with chemical composition of Y{sub 2}(CO{sub 3}){sub 3}·nH{sub 2}O, which were attracted to the surface of alumina nanoparticles and consequently, a core-shell structure was obtained. The use of ammonium hydrogen carbonate produced sheets of Y-compounds with chemical composition of Y(OH)CO{sub 3} covering the alumina nanoparticles. A fine-grained YAG ceramic (about 500 nm), presenting a non-negligible transparency (45% RIT at IR range) was obtained by the spark plasma sintering (SPS) of alumina-yttria nanocomposite synthesized in the urea system. This amount of transmission was obtained by only the sintering of the powder specimen without any colloidal forming process before sintering or adding any sintering aids or dopant elements. However, by spark plasma sintering of alumina-yttria nanocomposite powder synthesized in AHC system, an opaque YAG ceramic with an average grain size of 1.2 μm was obtained. - Highlights: • Urea proved to be an appropriate precipitant for obtaining a core-shell alumina/yttria nanocomposite. • Alumina/yttria nanocomposite powders with more appropriate morphology and highly sinterability. • A fine-grained YAG ceramic was obtained by SPS of alumina-yttria nanocomposite.

  14. Preparation of LuAG Powders with Single Phase and Good Dispersion for Transparent Ceramics Using Co-Precipitation Method

    Science.gov (United States)

    Pan, Liangjie; Jiang, Benxue; Fan, Jintai; Yang, Qiuhong; Zhou, Chunlin; Zhang, Pande; Mao, Xiaojian; Zhang, Long

    2015-01-01

    The synthesis of pure and well dispersed lutetium aluminum garnet (LuAG) powder is crucial and important for the preparation of LuAG transparent ceramics. In this paper, high purity and well dispersed LuAG powders have been synthesized via co-precipitation method with lutetium nitrate and aluminum nitrate as raw materials. Ammonium hydrogen carbonate (AHC) was used as the precipitant. The influence of aging time, pH value, and dripping speed on the prepared LuAG powders were investigated. It showed that long aging duration (>15 h) with high terminal pH value (>7.80) resulted in segregation of rhombus Lu precipitate and Al precipitate. By decreasing the initial pH value or accelerating the dripping speed, rhombus Lu precipitate was eliminated and pure LuAG nano powders were synthesized. High quality LuAG transparent ceramics with transmission >75% at 1064 nm were fabricated using these well dispersed nano LuAG powders. PMID:28793510

  15. Preparation of LuAG Powders with Single Phase and Good Dispersion for Transparent Ceramics Using Co-Precipitation Method

    Directory of Open Access Journals (Sweden)

    Liangjie Pan

    2015-08-01

    Full Text Available The synthesis of pure and well dispersed lutetium aluminum garnet (LuAG powder is crucial and important for the preparation of LuAG transparent ceramics. In this paper, high purity and well dispersed LuAG powders have been synthesized via co-precipitation method with lutetium nitrate and aluminum nitrate as raw materials. Ammonium hydrogen carbonate (AHC was used as the precipitant. The influence of aging time, pH value, and dripping speed on the prepared LuAG powders were investigated. It showed that long aging duration (>15 h with high terminal pH value (>7.80 resulted in segregation of rhombus Lu precipitate and Al precipitate. By decreasing the initial pH value or accelerating the dripping speed, rhombus Lu precipitate was eliminated and pure LuAG nano powders were synthesized. High quality LuAG transparent ceramics with transmission >75% at 1064 nm were fabricated using these well dispersed nano LuAG powders.

  16. Low temperature synthesis of nano alpha-alumina powder by two-step hydrolysis

    International Nuclear Information System (INIS)

    Yan, Ting; Guo, Xiaode; Zhang, Xiang; Wang, Zhixiang; Shi, Jinqiu

    2016-01-01

    Highlights: • The nano α-Al 2 O 3 with good dispersion was prepared by two-step hydrolysis. • α-Al 2 O 3 powders were added as seed particles in the hydrolysis. • This article indicated that the glucose could impel the γ-Al 2 O 3 transformed to α-Al 2 O 3 directly. • This article indicated that the addictive of α-Al 2 O 3 seed could improve the phase transformation rate of γ-Al 2 O 3 to α-Al 2 O 3 . • In this article, the pure α-Al 2 O 3 could be obtained by calcining at 1000 °C for 1.5 h. - Abstract: The ultral fine alpha-alumina powder has been successfully synthesized via two-step hydrolysis of aluminum isopropoxide. Glucose and polyvinyl pyrrolidone were used as surfactants during the appropriate processing step. The alpha-alumina powder was used as seed particles. Several synthesis parameters, such as the amount of seeds, surfactants, and calcination temperature, were studied by X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), Thermogravimetry-differential scanning calorimetry (TG-DSC), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The experimental results showed that glucose greatly lower the phase transformation temperature of alpha-alumina by impelling the gamma-alumina transformed to alpha-alumina directly, and the seed could improve the phase transformation rate of alpha-alumina, the polyvinylpyrrolidone have an effect on preventing excessive grain growth and agglomeration of alpha-alumina powder. Comparatively well dispersed alpha-alumina powder with particle size less than 50 nm can be synthesized through this method after calcinations at 1000 °C for 2 h.

  17. Calcium phosphate bioceramics prepared from wet chemically precipitated powders

    Directory of Open Access Journals (Sweden)

    Kristine Salma

    2010-03-01

    Full Text Available In this work calcium phosphates were synthesized by modified wet chemical precipitation route. Contrary to the conventional chemical precipitation route calcium hydroxide was homogenized with planetary mill. Milling calcium oxide and water in planetary ball mill as a first step of synthesis provides a highly dispersed calcium hydroxide suspension. The aim of this work was to study the influence of main processing parameters of wet chemical precipitation synthesis product and to control the morphology, phase and functional group composition and, consequently, thermal stability and microstructure of calcium phosphate bioceramics after thermal treatment. The results showed that it is possible to obtain calcium phosphates with different and reproducible phase compositions after thermal processing (hydroxyapatite [HAp], β-tricalcium phosphate [β-TCP] and HAp/β-TCP by modified wet-chemical precipitation route. The β-TCP phase content in sintered bioceramics samples is found to be highly dependent on the changes in technological parameters and it can be controlled with ending pH, synthesis temperature and thermal treatment. Pure, crystalline and highly thermally stable (up to 1300°C HAp bioceramics with homogenous grainy microstructure, grain size up to 200–250 nm and high open porosity can be successfully obtained by powder synthesized at elevated synthesis temperature of 70°C and stabilizing ending pH at 9.

  18. Amorphous phase formation in intermetallic Mg2Ni alloy synthesized by ethanol wet milling

    International Nuclear Information System (INIS)

    Wang, H.-W.; Chyou, S.-D.; Wang, S.-H.; Yang, M.-W.; Hsu, C.-Y.; Tien, H.-C.; Huang, N.-N.

    2009-01-01

    The hydriding/dehydriding properties of an intermetallic Mg 2 Ni alloy synthesized by wet ball milling in ethanol have been investigated. The appearance of the particle surface after different milling methods is one obvious difference. The alloyed powders prepared by either dry milling or wet milling under ethanol were characterized for phase content by X-ray diffractometer (XRD). The results show that two broad diffuse peaks, which are an ionic-organic-Mg amorphous material, appear in addition to the nickel element peaks. This unexpected amorphous phase has the special hydrogen absorbing/desorbing features.

  19. Nano or micro grained alumina powder? A choose before sintering

    Directory of Open Access Journals (Sweden)

    Román, R.

    2008-12-01

    Full Text Available Two different wet routes have been used to synthesize alumina powders in order to compare the characteristics of the final product and its behaviour during sintering. The Homogeneous Precipitation (HP gives rise to nanoparticulated powders of about 2 nm. However, such particles quickly aggregate and grow with calcination temperature. The Polymerized Organic-Inorganic Synthesis (POI produces homogeneous particle size powders (about 1 micron after resin charring. The characterization of the powder surface is the basis of an efficient process control. Particle characterization parameters (morphology, crystallinity and degree of aggregation are characterized by different techniques, such as DTA/TG, IR, XRD, SEM and TEM, and compared between these synthesis methods. The results show the evolution from the amorphous to the corundum alumina phase for both processes and their ability for sintering, as well discuses the beneficial of nanoparticles obtained by HP during sintering.

    Se han utilizado dos diferentes síntesis por vía húmeda para la preparación de polvos de alúmina con el fin de comparar las características de los productos finales y su comportamiento durante la sinterización. La Precipitación Homogénea (HP da lugar a polvos nanoparticulados de unos 2nm. Se observa sin embargo, como estas partículas se agregan rápidamente y crecen con la temperatura de calcinación. La Síntesis por Polimerización Orgánica-Inorgánica (POI produce polvos de tamaño de partícula homogéneo (en torno a 1 micra después de la descomposión de la resina. La caracterización de la superficie de los polvos es la base de un control eficiente del proceso. Los parámetros de caracterización de las partículas obtenidas (morfología, cristalinidad y grado de agregación se obtienen por diferentes técnicas como DTA/TG, IR, XRD, SEM y TEM, y se comparan entre estos métodos de síntesis. Los resultados muestran la evolución desde el amorfo a la fase

  20. Microstructural, structural and optical properties of nanoparticles of PbO-CrO3 pigment synthesized by a soft route

    Directory of Open Access Journals (Sweden)

    V. D. Araújo

    2015-03-01

    Full Text Available PbCrO4 and Pb2CrO5 particles were synthesized by the polymeric precursor method. Structural and microstructural properties of the particles were characterized by scanning electron microscopy with field emission gun, X-ray diffraction, and Raman spectroscopy techniques. The diffuse reflectance technique was employed to study the optical properties in the 400-700 nm range. The optical bandgap of the samples was obtained indirectly. Colorimetric coordinates L*, a*, b* were calculated for the pigment powders as a function of the heat treatment (400-700 ºC. The powders displayed colors ranging from green to red. X-ray diffraction patterns showed the presence of monoclinic PbCrO4 phase in green samples, while red powders had a monoclinic Pb2CrO5 phase structure. The Raman spectra of the PbCrO4 and Pb2CrO5 powders were in good agreement with those reported in the literature. The synthesized compounds can be used as green and red pigments with high thermal stability.

  1. Preparation procedure for spherical titanium powders by RF induction plasma

    International Nuclear Information System (INIS)

    Gu Zhongtao; Jin Yuping; Ye Gaoying

    2011-01-01

    The paper uses the single-factor method for the study of spherical titanium powder preparation process. Titanium powders with excellent sphericity can be prepared through controlling and regulating the radio frequency plasma anode working current and voltage, central gas flow rate, sheath gas flow rate, powder-carrying gas flow rate, negative ventilation pressure and powder feed rate, etc. Spheroidization of titanium powders with a size of (17.0±2.0) μm is performed by radio frequency plasma technology. With the increase of negative ventilation pressure, the spheroidization rate of titanium powders increases firstly and then decreases rapidly at the turning point around 1800 Pa. With the rate of powder feed increasing, the spheroidization rate of titanium powders increases firstly. When the powder feed rate is greater than 90.0 g/min, the spheroidization rate of titanium powders reduces rapidly as the powder feed rate increases. (authors)

  2. Screening and classification of ceramic powders

    Science.gov (United States)

    Miwa, S.

    1983-01-01

    A summary is given of the classification technology of ceramic powders. Advantages and disadvantages of the wet and dry screening and classification methods are discussed. Improvements of wind force screening devices are described.

  3. Advances in food powder agglomeration engineering.

    Science.gov (United States)

    Cuq, B; Gaiani, C; Turchiuli, C; Galet, L; Scher, J; Jeantet, R; Mandato, S; Petit, J; Murrieta-Pazos, I; Barkouti, A; Schuck, P; Rondet, E; Delalonde, M; Dumoulin, E; Delaplace, G; Ruiz, T

    2013-01-01

    Food powders are used in everyday life in many ways and offer technological solutions to the problem of food production. The natural origin of food powders, diversity in their chemical composition, variability of the raw materials, heterogeneity of the native structures, and physicochemical reactivity under hydrothermal stresses contribute to the complexity in their behavior. Food powder agglomeration has recently been considered according to a multiscale approach, which is followed in the chapter layout: (i) at the particle scale, by a presentation of particle properties and surface reactivity in connection with the agglomeration mechanisms, (ii) at the mechanisms scale, by describing the structuration dynamics of agglomerates, (iii) at the process scale, by a presentation of agglomeration technologies and sensors and by studying the stress transmission mode in the powder bed, and finally (iv) by an integration of the acquired knowledge, thanks to a dimensional analysis carried out at each scale. Copyright © 2013 Elsevier Inc. All rights reserved.

  4. Generation and characterization of nano aluminium powder ...

    Indian Academy of Sciences (India)

    TECS

    Generation and characterization of nano aluminium powder obtained through wire ... Department of Aerospace Engineering, Indian Institute of Technology. Madras, Chennai 600 .... pressure developed due to current flow (z-Pinch). Figure 2.

  5. Compaction of amorphous iron–boron powder

    DEFF Research Database (Denmark)

    Hendriksen, Peter Vang; Mørup, Steen; Koch, Christian

    1993-01-01

    Large scale practical use of bulk amorphous alloys requires the capability of molding the material to a desired design, for instance by compaction of an amorphous powder. This is a difficult task because the sintering temperature is limited by the crystallization temperature of the alloy.1 Here we......, should facilitate a compaction. The passivation layer, however, impedes a compaction. Isostatic pressing at 540 K at a pressure of 200 MPa clearly illustrated this; pellets pressed from passivated powder were much more brittle than pellets pressed from unpassivated powder. The density of the pellets...... was very low ([approximately-equal-to]25% of the density of bulk FeB). We have designed a die for uniaxial pressing in which the compaction can be performed without exposing the powder to air and have obtained densities larger than 60% of that of bulk FeB. We have reported studies of the dependence...

  6. Strain-enhanced sintering of iron powders

    Energy Technology Data Exchange (ETDEWEB)

    Amador, D.R.; Torralba, J.M. [Universidad Carlos III de Madrid, Departamento de Ciencias de Materiales e Ingenieria Metalurgica, Leganes, Madrid (Spain); Monge, M.A.; Pareja, R. [Universidad Carlos III de Madrid, Departamento de Fisica, Madrid (Spain)

    2005-02-01

    Sintering of ball-milled and un-milled Fe powders has been investigated using dilatometry, X-ray, density, and positron annihilation techniques. A considerable sintering enhancement is found in milled powders showing apparent activation energies that range between 0.44 and 0.80 eV/at. The positron annihilation results, combined with the evolution of the shrinkage rate with sintering temperature, indicate generation of lattice defects during the sintering process of milled and un-milled powders. The sintering enhancement is attributed to pipe diffusion along the core of moving dislocations in the presence of the vacancy excess produced by plastic deformation. Positron annihilation results do not reveal the presence of sintering-induced defects in un-milled powders sintered above 1200 K, the apparent activation energy being in good agreement with that for grain-boundary diffusion in {gamma}-Fe. (orig.)

  7. Metal powder production by gas atomization

    Science.gov (United States)

    Ting, E. Y.; Grant, N. J.

    1986-01-01

    The confined liquid, gas-atomization process was investigated. Results from a two-dimensional water model showed the importance of atomization pressure, as well as delivery tube and atomizer design. The atomization process at the tip of the delivery tube was photographed. Results from the atomization of a modified 7075 aluminum alloy yielded up to 60 wt pct. powders that were finer than 45 microns in diameter. Two different atomizer designs were evaluated. The amount of fine powders produced was correlated to a calculated gas-power term. An optimal gas-power value existed for maximized fine powder production. Atomization at gas-power greater than or less than this optimal value produced coarser powders.

  8. Shock-induced modification of inorganic powders

    International Nuclear Information System (INIS)

    Graham, R.A.; Morosin, B.; Venturini, E.L.; Beauchamp, E.K.; Hammetter, W.F.

    1984-01-01

    The results of studies performed to quantify the characteristics of TiO2, ZrO2 and Si3N4 powders exposed to explosive loading and post-shock analysis are reported. The shocks were produced with plane wave generators and explosive pads impinging on steel disks, a copper recovery fixture, and then the samples. Peak pressures of 13 and 17 GPa were attained, along with 40 GPz at the center of the powder cavity. Data are provided on the changes occurring during the explosive densification and X-ray and paramagnetic studies of the products. Only fractured disks were obtained in the trials. The shock-treated materials were more free flowing than the original powders, which were fluffy. Post-shock annealing was a significant feature of the treated powders

  9. Advances in beryllium powder consolidation simulations

    International Nuclear Information System (INIS)

    Reardon, B.J.

    1998-01-01

    A fuzzy logic based multiobjective genetic algorithm (GA) is introduced and the algorithm is used to optimize micromechanical densification modeling parameters for warm isopressed beryllium powder, HIPed copper powder and CIPed/sintered and HIPed tantalum powder. In addition to optimizing the main model parameters using the experimental data points as objective functions, the GA provides a quantitative measure of the sensitivity of the model to each parameter, estimates the mean particle size of the powder, and determines the smoothing factors for the transition between stage 1 and stage 2 densification. While the GA does not provide a sensitivity analysis in the strictest sense, and is highly stochastic in nature, this method is reliable and reproducible in optimizing parameters given any size data set and determining the impact on the model of slight variations in each parameter

  10. RF induction plasma spheroidization of tungsten powders

    International Nuclear Information System (INIS)

    Gu Zhogntao; Ye Gaoying; Liu Chuandong; Tong Honghui

    2009-01-01

    Irregularly-shaped tungsten powders (average granular sizes of 512 μm) have been spheroidized by radio frequency (RF)induction plasma. The effects of feed rate, mode of material dispersion, particle size on spheroidization efficiency are investigated. Experimental results show that the spheroidization efficiency decreases rapidly when the feed rate increases to more than 95 g/min. Only 30% spheroidization efficiency is gained at the feed rate of 135.75 g/min. The spheroidization efficiency is also affected by the flow rate of carrier gas. When the flow rate of carrier gas is 0.12 m 3 /h, the dispersion effect is the best, and the spheroidization efficiency is almost 100%. The apparent density of tungsten powders increases a bit with the increase of spheroidization efficiency. And the particle size uniformity of spheroidized tungsten powders is in accordance with that of original powders. (authors)

  11. Spray drying of beryllium oxide powder

    International Nuclear Information System (INIS)

    Sepulveda, J.L.; Kahler, D.A.

    1991-01-01

    Forming of beryllia ceramics through dry pressing requires the agglomeration of the powder through spray drying. To produce high quality fired ceramics it is necessary to disperse/grind the primary powder prior to binder addition. Size reduction of the powder is accomplished using an aqueous system in Vibro-Energy mills (VEM) charged with beryllia media to minimize contamination. Two VEM mills of different size were used to characterize the grinding operation. Details of the grinding kinetics are described within the context of the Macroscopic Population Balance Model approach. Spray drying of the ceramic slurry was accomplished with both a centrifugal atomizer and a two fluid nozzle atomizer. Two different spray dryers were used. Important operating parameters affecting the size distribution of the spray dried powder are discussed

  12. An application of powder metallurgy to dentistry.

    Science.gov (United States)

    Oda, Y; Ueno, S; Kudoh, Y

    1995-11-01

    Generally, the dental casting method is used to fabricate dental prostheses made with metal. The method of fabricating dental prostheses from sintered titanium alloy has certain advantages: the elimination of casting defects, a sintering temperature that is lower than the melting point, and a shorter processing time. By examining (1) the properties of green, sintered compacts of titanium powder, (2) the effects of adding aluminum powder on the properties of green, sintered compacts of Ti-Al compound, and (3) the effects of adding copper powder on the properties of green, sintered compacts of Ti-Al-Cu compound, the authors developed a sintered titanium alloy on a trial basis. Because the properties satisfied the requirements of dental restorations, a powder metallurgical method of making dental restorations from this sintered titanium alloy was devised. Applications of such sintered titanium alloys for the metal coping of metal-ceramic crowns and denture base plates were discussed.

  13. Role of forgings in powder metallurgy industry

    International Nuclear Information System (INIS)

    Hayes, A.F.; DeRidder, A.J.

    1975-01-01

    Forging of powder metallurgy materials is discussed. Information and data are included on forging powder metallurgy W, Mo, In 100, Rene 95, Astroloy, Be, and Ti. It is noted that the combination of powder metallurgy and forging work provides the best product from standpoints of reproducibility, freedom from segregation, low scrap rate, and uniform mechanical properties. Experience is being used to develop contour forging from hot isostatic pressed billets or preforms. The quality of this product is under evaluation. Results show steady improvement and it is anticipated that continued effort will soon produce a reliable, less costly product. Forging can continue to be relied upon to correct subtle defects present in powder metallurgy material

  14. Surface chemistry and microscopy of food powders

    Science.gov (United States)

    Burgain, Jennifer; Petit, Jeremy; Scher, Joël; Rasch, Ron; Bhandari, Bhesh; Gaiani, Claire

    2017-12-01

    Despite high industrial and scientific interest, a comprehensive review of the surface science of food powders is still lacking. There is a real gap between scientific concerns of the field and accessible reviews on the subject. The global description of the surface of food powders by multi-scale microscopy approaches seems to be essential in order to investigate their complexity and take advantage of their high innovation potential. Links between these techniques and the interest to develop a multi-analytical approach to investigate scientific questions dealing with powder functionality are discussed in the second part of the review. Finally, some techniques used in others fields and showing promising possibilities in the food powder domain will be highlighted.

  15. Synthesis of single-phase L10-FeNi magnet powder by nitrogen insertion and topotactic extraction

    OpenAIRE

    Goto, Sho; Kura, Hiroaki; Watanabe, Eiji; Hayashi, Yasushi; Yanagihara, Hideto; Shimada, Yusuke; Mizuguchi, Masaki; Takanashi, Koki; Kita, Eiji

    2017-01-01

    Tetrataenite (L10-FeNi) is a promising candidate for use as a permanent magnet free of rare-earth elements because of its favorable properties. In this study, single-phase L10-FeNi powder with a high degree of order was synthesized through a new method, nitrogen insertion and topotactic extraction (NITE). In the method, FeNiN, which has the same ordered arrangement as L10-FeNi, is formed by nitriding A1-FeNi powder with ammonia gas. Subsequently, FeNiN is denitrided by topotactic reaction to ...

  16. Acid-base properties of ceramic powders

    International Nuclear Information System (INIS)

    Bleier, A.

    1983-01-01

    This chapter addresses the fundamental aspects of potentiometric titration, electrokinetics, and conductometric titration in evaluating surface and interfacial thermodynamic behavior. Emphasizes the characterization of aqueous systems which are pertinent to the processing of ceramic powders. Attempts to clarify the role of novel analytical techniques that will increasingly contribute to the advanced characterization of ceramic powders. Evaluates recently developed acid-base and complexation concepts and their applications to the processing of oxide ceramics

  17. Fuel powder production from ductile uranium alloys

    International Nuclear Information System (INIS)

    Clark, C.R.; Meyer, M.K.

    1998-01-01

    Metallic uranium alloys are candidate materials for use as the fuel phase in very-high-density LEU dispersion fuels. These ductile alloys cannot be converted to powder form by the processes routinely used for oxides or intermetallics. Three methods of powder production from uranium alloys have been investigated within the US-RERTR program. These processes are grinding, cryogenic milling, and hydride-dehydride. In addition, a gas atomization process was investigated using gold as a surrogate for uranium. (author)

  18. Plasma spheroidization and cladding of powders

    Energy Technology Data Exchange (ETDEWEB)

    Petrunichev, V.A.; Averin, V.V.; Sorokin, L.M.; Koroleva, E.B.

    1987-02-01

    With reference to experimental results for nickel and chromium alloys, it is shown that complex alloy powders can be spheroidized in plasma discharges using an argon plasma with hydrogen. The spheroidizing process is accompanied by the reduction of surface oxides, with uniform element distribution within the particles; the granulometric composition of the particles is preserved. It is also shown that plasma technology can be used for producing metal-clad oxide and carbide powders, which improve the performance of cermets and coatings.

  19. Cellulose powder from Cladophora sp. algae.

    Science.gov (United States)

    Ek, R; Gustafsson, C; Nutt, A; Iversen, T; Nyström, C

    1998-01-01

    The surface are and crystallinity was measured on a cellulose powder made from Cladophora sp. algae. The algae cellulose powder was found to have a very high surface area (63.4 m2/g, N2 gas adsorption) and build up of cellulose with a high crystallinity (approximately 100%, solid state NMR). The high surface area was confirmed by calculations from atomic force microscope imaging of microfibrils from Cladophora sp. algae.

  20. Advanced powder metallurgy aluminum alloys and composites

    Science.gov (United States)

    Lisagor, W. B.; Stein, B. A.

    1982-01-01

    The differences between powder and ingot metallurgy processing of aluminum alloys are outlined. The potential payoff in the use of advanced powder metallurgy (PM) aluminum alloys in future transport aircraft is indicated. The national program to bring this technology to commercial fruition and the NASA Langley Research Center role in this program are briefly outlined. Some initial results of research in 2000-series PM alloys and composites that highlight the property improvements possible are given.

  1. Powder metallurgy in aerospace research: A survey

    Science.gov (United States)

    Blakeslee, H. W.

    1971-01-01

    The various techniques by which powders can be produced, as pure metals or as alloys, are discussed; the methods by which these powders can be formed into the final parts are explained as well as further processing that may be necessary to meet specific requirements. The NASA developments are detailed, and references are provided for those who wish to obtain further information characteristic of any methodology.

  2. Positron lifetime studies on thorium oxide powders

    International Nuclear Information System (INIS)

    Upadhyaya, D.D.; Muraleedharan, R.V.; Sharma, B.D.

    1982-01-01

    Positron lifetime spectra have been studied for ThO 2 powders, calcined at different temperatures and having different particle sizes. Three lifetime components could be resolved, the longest component being of low intensity. An observed strong dependence on the particle size of the annihilation process and the variation of positronium diffusion constant is explained on the basis of defect density variations in these powders. (author)

  3. New automated pellet/powder assay system

    International Nuclear Information System (INIS)

    Olsen, R.N.

    1975-01-01

    This paper discusses an automated, high precision, pellet/ powder assay system. The system is an active assay system using a small isotopic neutron source and a coincidence detection system. The handling of the pellet powder samples has been automated and a programmable calculator has been integrated into the system to provide control and data analysis. The versatile system can assay uranium or plutonium in either active or passive modes

  4. Molybdenum plasma spray powder, process for producing said powder, and coating made therefrom

    International Nuclear Information System (INIS)

    Lafferty, W.D.; Cheney, R.F.; Pierce, R.H.

    1979-01-01

    Plasma spray powders of molybdenum particles containing 0.5 to 15 weight percent oxygen and obtained by reacting molybdenum particles with oxygen or oxides in a plasma, form plasma spray coatings exhibiting hardness comparable to flame sprayed coatings formed from molybdenum wire and plasma coatings of molybdenum powders. Such oxygen rich molybdenum powders may be used to form wear resistant coatings, such as for piston rings. (author)

  5. [Use of powder metallurgy for development of implants of Co-Cr-Mo alloy powder].

    Science.gov (United States)

    Dabrowski, J R

    2001-04-01

    This paper discusses the application of powder metallurgy for the development of porous implantation materials. Powders obtained from Co-Cr-Mo alloy with different carbon content by water spraying and grinding, have been investigated. Cold pressing and rotary re-pressing methods were used for compressing the powder. It was found that the sintered materials obtained from water spraying have the most advantageous properties.

  6. Sonochemically synthesized MnO2 nanoparticles as electrode material for supercapacitors.

    Science.gov (United States)

    Gnana Sundara Raj, Balasubramaniam; Asiri, Abdullah M; Qusti, Abdullah H; Wu, Jerry J; Anandan, Sambandam

    2014-11-01

    In this study, manganese oxide (MnO2) nanoparticles were synthesized by sonochemical reduction of KMnO4 using polyethylene glycol (PEG) as a reducing agent as well as structure directing agent under room temperature in short duration of time and characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscope (SEM), Transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) analysis. A supercapacitor device constructed using the ultrasonically-synthesized MnO2 nanoparticles showed maximum specific capacitance (SC) of 282Fg(-1) in the presence of 1M Ca(NO3)2 as an electrolyte at a current density of 0.5mAcm(-2) in the potential range from 0.0 to 1.0V and about 78% of specific capacitance was retained even after 1000 cycles indicating its high electrochemical stability. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. In vitro toxicity test of nano-sized magnesium oxide synthesized via solid-phase transformation

    Science.gov (United States)

    Zheng, Jun; Zhou, Wei

    2018-04-01

    Nano-sized magnesium oxide (MgO) has been a promising potential material for biomedical pharmaceuticals. In the present investigation, MgO nanoparticles synthesized through in-situ solid-phase transformation based on the previous work (nano-Mg(OH)2 prepared by precipitation technique) using magnesium nitrate and sodium hydroxide. The phase structure and morphology of the MgO nanoparticles are characterized by X-ray powder diffraction (XRD), selected area electronic diffraction (SAED) and transmission electron microscopy (TEM) respectively. In vitro hemolysis tests are adopted to evaluate the toxicity of the synthesized nano-MgO. The results evident that nano-MgO with lower concentration is slightly hemolytic, and with concentration increasing nano-MgO exhibit dose-responsive hemolysis.

  8. Optimization of Premix Powders for Tableting Use.

    Science.gov (United States)

    Todo, Hiroaki; Sato, Kazuki; Takayama, Kozo; Sugibayashi, Kenji

    2018-05-08

    Direct compression is a popular choice as it provides the simplest way to prepare the tablet. It can be easily adopted when the active pharmaceutical ingredient (API) is unstable in water or to thermal drying. An optimal formulation of preliminary mixed powders (premix powders) is beneficial if prepared in advance for tableting use. The aim of this study was to find the optimal formulation of the premix powders composed of lactose (LAC), cornstarch (CS), and microcrystalline cellulose (MCC) by using statistical techniques. Based on the "Quality by Design" concept, a (3,3)-simplex lattice design consisting of three components, LAC, CS, and MCC was employed to prepare the model premix powders. Response surface method incorporating a thin-plate spline interpolation (RSM-S) was applied for estimation of the optimum premix powders for tableting use. The effect of tablet shape identified by the surface curvature on the optimization was investigated. The optimum premix powder was effective when the premix was applied to a small quantity of API, although the function of premix was limited in the case of the formulation of large amount of API. Statistical techniques are valuable to exploit new functions of well-known materials such as LAC, CS, and MCC.

  9. Tantalum powder consolidation, modeling and properties

    International Nuclear Information System (INIS)

    Bingert, S.R.; Vargas, V.D.; Sheinberg, H.C.

    1996-01-01

    A systematic approach was taken to investigate the consolidation of tantalum powders. The effects of sinter time, temperature and ramp rate; hot isostatic pressing (HIP) temperature and time; and powder oxygen content on consolidation density, kinetics, microstructure, crystallographic texture, and mechanical properties have been evaluated. In general, higher temperatures and longer hold times resulted in higher density compacts with larger grain sizes for both sintering and HIP'ing. HIP'ed compacts were consistently higher in density than sintered products. The higher oxygen content powders resulted in finer grained, higher density HIP'ed products than the low oxygen powders. Texture analysis showed that the isostatically processed powder products demonstrated a near random texture. This resulted in isotropic properties in the final product. Mechanical testing results showed that the HIP'ed powder products had consistently higher flow stresses than conventionally produced plates, and the sintered compacts were comparable to the plate material. A micromechanics model (Ashby HIP model) has been employed to predict the mechanisms active in the consolidation processes of cold isostatic pressing (CIP), HIP and sintering. This model also predicts the density of the end product and whether grain growth should be expected under the applied processing conditions

  10. Electrical conductivity of metal powders under pressure

    Science.gov (United States)

    Montes, J. M.; Cuevas, F. G.; Cintas, J.; Urban, P.

    2011-12-01

    A model for calculating the electrical conductivity of a compressed powder mass consisting of oxide-coated metal particles has been derived. A theoretical tool previously developed by the authors, the so-called `equivalent simple cubic system', was used in the model deduction. This tool is based on relating the actual powder system to an equivalent one consisting of deforming spheres packed in a simple cubic lattice, which is much easier to examine. The proposed model relates the effective electrical conductivity of the powder mass under compression to its level of porosity. Other physically measurable parameters in the model are the conductivities of the metal and oxide constituting the powder particles, their radii, the mean thickness of the oxide layer and the tap porosity of the powder. Two additional parameters controlling the effect of the descaling of the particle oxide layer were empirically introduced. The proposed model was experimentally verified by measurements of the electrical conductivity of aluminium, bronze, iron, nickel and titanium powders under pressure. The consistency between theoretical predictions and experimental results was reasonably good in all cases.

  11. Microstructure Analysis of Synthesized LiBOB

    Directory of Open Access Journals (Sweden)

    Etty Marti Wigayati

    2015-11-01

    Full Text Available Lithium bis (oxalate borate or LiBOB is an active material used as the electrolyte for lithium battery application. LiBOB (LiB(C2O42 powder was prepared from LiOH, H2C2O4 and H3BO3. The employed method was solid state reaction. LiBOB powder produced from the reaction was then observed using SEM and TEM. Surface area was analyzed using Quantachrome Nova 4200e. From the analysis analyzed using XRD to identify the resulting phases, crystal structure, and crystallite size. The functional groups were analyzed using FT-IR. The particle morphology was result, it was seen that the resulted phases were C4LiBO8 and LiB(C2O42.H2O, the crystal structure was orthorhombic with space group Pbca and Pnma. From the particle morphology observation it was shown that micro pores were created irregularly. When the observation was deepened, nanopores with elongated round shape were seen within the micropores. The pore size was approximately 50–100 nm. The surface area, total pore volume, and average pore diameter of LiBOB powder was 88.556 m2/g, 0.4252 cm3/g, and 19.2 nm respectively.

  12. In situ Fabrication of Fe-TiB{sub 2} Nanocomposite Powder by Planetary Ball Milling and Subsequent Heat-treatment of FeB and TiH{sub 2} Powder Mixture

    Energy Technology Data Exchange (ETDEWEB)

    Huynh, Xuan-Khoa [Hanoi Uneversity of Science and Technology, Hanoi (Viet Nam); Bae, Sun-Woo; Kim, Ji Soon [University of Ulsan, Ulsan (Korea, Republic of)

    2017-01-15

    Fe-TiB{sub 2} powder was synthesized in-situ by the planetary ball milling and subsequent heat-treatment of an iron boride (FeB) and titanium hydride (TiH{sub 2}) powder mixture. Mechanical activation of the (FeB+TiH{sub 2}) powder mixtures was observed after a milling time of 3 hours at 700 rpm of rotation speed, but activation was not the same after 1 hour milling time. The particle size of the (FeB+ TiH{sub 2}) powder mixture was reduced to the nanometer scale, and each constituent was homogeneously distributed. A sharp exothermic peak was observed at a lower temperature (749 ℃) on the DSC curves for the (FeB+TiH{sub 2}) powder mixture milled for 3 hours, compared to the one milled for 1 hour (774 ℃). These peaks were confirmed to have resulted from the formation reaction of the TiB{sub 2} phase, from Ti and B elements in the FeB. The Fe-TiB{sub 2} composite powder fabricated in situ exhibited only two phases of Fe and TiB{sub 2} with homogeneous distribution. The size of the TiB{sub 2} particulates in the Fe matrix was less than 5 nm.

  13. Preparation of tris(8-hydroxyquinolinato)aluminum thin films by sputtering deposition using powder and pressed powder targets

    Science.gov (United States)

    Kawasaki, Hiroharu; Ohshima, Tamiko; Yagyu, Yoshihito; Ihara, Takeshi; Tanaka, Rei; Suda, Yoshiaki

    2017-06-01

    Tris(8-hydroxyquinolinato)aluminum (Alq3) thin films, for use in organic electroluminescence displays, were prepared by a sputtering deposition method using powder and pressed powder targets. Experimental results suggest that Alq3 thin films can be prepared using powder and pressed powder targets, although the films were amorphous. The surface color of the target after deposition became dark brown, and the Fourier transform infrared spectroscopy spectrum changed when using a pressed powder target. The deposition rate of the film using a powder target was higher than that using a pressed powder target. That may be because the electron and ion densities of the plasma generated using the powder target are higher than those when using pressed powder targets under the same deposition conditions. The properties of a thin film prepared using a powder target were almost the same as those of a film prepared using a pressed powder target.

  14. Structural characterization of nanocrystalline cadmium sulphide powder prepared by solvent evaporation technique

    Science.gov (United States)

    Pandya, Samir; Tandel, Digisha; Chodavadiya, Nisarg

    2018-05-01

    CdS is one of the most important compounds in the II-VI group of semiconductor. There are numerous applications of CdS in the form of nanoparticles and nanocrystalline. Semiconductors nanoparticles (also known as quantum dots), belong to state of matter in the transition region between molecules and solids, have attracted a great deal of attention because of their unique electrical and optical properties, compared to bulk materials. In the field of optoelectronic, nanocrystalline form utilizes mostly in the field of catalysis and fluid technology. Considering these observations, presented work had been carried out, i.e. based on the nanocrystalline material preparation. In the present work CdS nano-crystalline powder was synthesized by a simple and cost effective chemical technique to grow cadmium sulphide (CdS) nanoparticles at 200 °C with different concentrations of cadmium. The synthesis parameters were optimized. The synthesized powder was structurally characterized by X-ray diffraction and particle size analyzer. In the XRD analysis, Micro-structural parameters such as lattice strain, dislocation density and crystallite size were analysed. The broadened diffraction peaks indicated nanocrystalline particles of the film material. In addition to that the size of the prepared particles was analyzed by particle size analyzer. The results show the average size of CdS particles ranging from 80 to 100 nm. The overall conclusion of the work can be very useful in the synthesis of nanocrystalline CdS powder.

  15. Effect of zirconia content and powder processing mechanical properties of gelcasted ZTA composite

    International Nuclear Information System (INIS)

    Khoshkalam, M.; Faghihi-Sani, M.A.; Nojoomi, A.

    2013-01-01

    Addition of fine zirconia particles in the alumina matrix in order to produce ZTA composite is a well-known method for improving the mechanical properties of alumina ceramics such as flexural strength and fracture toughness. Increasing homogeneity and reducing alumina grain size are two key factors for achieving proper mechanical properties in this ceramic matrix composite. In this work two batches of ZTA powder precursor were prepared through mixing of alumina and zirconia by ball milling and in situ synthesis of ZTA composite via solution combustion method. The bending strength testing samples were fabricated through gel-casting process. The effects of different powder processing methods as well as zirconia contents on microstructural homogeneity and mechanical properties of ZTA composites were investigated. The samples produced by solution combustion synthesized powder yielded higher homogeneity, finer microstructure and higher flexural strength. Results showed an upswing in the fracture toughness for the synthesized samples even up to 20 vol% zirconia, while the mixed samples depicted optimum fracture toughness in 10 vol% zirconia content. (author)

  16. Thermoluminescence in HfO_2:Eu"3"+ powders irradiated in UV

    International Nuclear Information System (INIS)

    Ceron R, P. V.; Montes R, E.; Rivera M, T.; Diaz G, J. A. I.; Guzman M, J.

    2016-10-01

    Various inorganic compounds synthesized for photo luminescent applications have also presented a thermoluminescent (Tl) response, for example the metal oxides doped with rare earths. This property extends the use of these materials to the radiation dosimetry. For this reason, in this work the Tl response is presented in HfO_2:Eu"3"+ powders synthesized by the hydrothermal path, exposed to ultraviolet (UV) radiation of 254 nm. The kinetic parameters of its brightness curve were also calculated using the Chen expressions and the analysis method based on the shape of the curve. For the powders irradiated for 10 min the highest Tl response corresponds to the sample with 5% of the impurity, which is 6.5 times higher than the signal corresponding to the intrinsic sample. Its bright curve shows a main peak with a maximum in 148 degrees Celsius and a second order kinetics. Another test with the same material shows the Tl response against the exposure time, with a maximum in the 3 minutes. These calculations and tests constitute a first approach for the study of these powders as Tl dosimeter for UV radiation. (Author)

  17. Equilibrium binding studies of mono, di and triisocyanide ligands on Au powder surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ontko, Alyn [Iowa State Univ., Ames, IA (United States)

    1997-10-08

    The author`s group has previously shown that isocyanides are readily adsorbed from solutions to Au powder and bind to the Au surface in an end-on fashion through the terminal carbon. Later work demonstrated that the equilibrium constants for the reversible adsorption of electronically inequivalent isocyanides could be obtained using the Langmuir isotherm technique. This dissertation describes two projects completed which complement the initial findings of this group. Initially, several alkylisocyanides were synthesized to examine the effect of tail length on Au powder adsorption. It was observed that the length of the alkyl chain affected not only the Au surface binding affinity, but also the rate of surface saturation and saturation coverage values. Direct competition studies were also studied using a 13C-labeled isocyanide. These studies demonstrated the stabilization afforded by substrate-substrate packing forces in SAM`s formed by the longer chain isocyanides. In a second study, di and triisocyanides were synthesized to determine the effect that the length of the connecting link and the number of isocyanide groups (as points of attachment) have on Au adsorption stability. The work in this area describes the binding modes, relative binding affinities and surface coverage values for a series of flexible alkyl and xylyldiisocyanides on Au powder surfaces. This report contains only the introductory material, and general summary. Two chapters have been processed separately. 56 refs.

  18. Synthesizing Modular Invariants for Synchronous Code

    Directory of Open Access Journals (Sweden)

    Pierre-Loic Garoche

    2014-12-01

    Full Text Available In this paper, we explore different techniques to synthesize modular invariants for synchronous code encoded as Horn clauses. Modular invariants are a set of formulas that characterizes the validity of predicates. They are very useful for different aspects of analysis, synthesis, testing and program transformation. We describe two techniques to generate modular invariants for code written in the synchronous dataflow language Lustre. The first technique directly encodes the synchronous code in a modular fashion. While in the second technique, we synthesize modular invariants starting from a monolithic invariant. Both techniques, take advantage of analysis techniques based on property-directed reachability. We also describe a technique to minimize the synthesized invariants.

  19. Microstructural and electrical changes in nickel manganite powder induced by mechanical activation

    International Nuclear Information System (INIS)

    Savic, S.M.; Mancic, L.; Vojisavljevic, K.; Stojanovic, G.; Brankovic, Z.; Aleksic, O.S.; Brankovic, G.

    2011-01-01

    Highlights: → The influence of mechanical activation on microstructure evolution in the nickel manganite powder was investigated as well as electrical properties of the sintered samples. → Structural refinement obtained by Topas-Academic software based on Rietveld analysis showed that the milling process remarkably changed the powder morphology and microstructure. → SEM studies of sintered samples also revealed the strong influence of milling time on ceramics density (increases with milling time). → The electrical properties of ceramic samples are clearly conditioned by terms of synthesis, in our case the time of mechanical activation. → The highest density and higher values of dielectric constant were achieved at the sample activated for 45 min. -- Abstract: Nickel manganite powder synthesized by calcination of a stoichiometric mixture of manganese and nickel oxide was additionally mechanically activated in a high energy planetary ball mill for 5-60 min in order to obtain a pure NiMn 2 O 4 phase. The as-prepared powders were uniaxially pressed into disc shape pellets and then sintered for 60 min at 1200 o C. Changes in the particle morphology induced by mechanical activation were monitored using scanning electron microscopy, while changes in powder structural characteristics were followed using X-ray powder diffraction. The ac impedance spectroscopy was performed on sintered nickel manganite samples at 25 o C, 50 o C and 80 o C. It was shown that mechanical activation intensifies transport processes causing a decrease in the average crystallites size, while longer activation times can lead to the formation of aggregates, defects and increase of lattice microstrains. The observed changes in microstructures were correlated with measured electrical properties in order to define optimal processing conditions.

  20. Microstructural and electrical changes in nickel manganite powder induced by mechanical activation

    Energy Technology Data Exchange (ETDEWEB)

    Savic, S.M., E-mail: slavicas@cms.bg.ac.rs [Institute for Multidisciplinary Research-University of Belgrade, Kneza Viseslava 1a, 11030 Belgrade (Serbia); Mancic, L. [Institute of Technical Sciences SASA, Knez Mihailova 35/IV, 11000 Belgrade (Serbia); Vojisavljevic, K. [Institute for Multidisciplinary Research-University of Belgrade, Kneza Viseslava 1a, 11030 Belgrade (Serbia); Stojanovic, G. [Faculty of Technical Sciences University of Novi Sad, Trg Dositeja Obradovica 6, 21000 Novi Sad (Serbia); Brankovic, Z.; Aleksic, O.S.; Brankovic, G. [Institute for Multidisciplinary Research-University of Belgrade, Kneza Viseslava 1a, 11030 Belgrade (Serbia)

    2011-07-15

    Highlights: {yields} The influence of mechanical activation on microstructure evolution in the nickel manganite powder was investigated as well as electrical properties of the sintered samples. {yields} Structural refinement obtained by Topas-Academic software based on Rietveld analysis showed that the milling process remarkably changed the powder morphology and microstructure. {yields} SEM studies of sintered samples also revealed the strong influence of milling time on ceramics density (increases with milling time). {yields} The electrical properties of ceramic samples are clearly conditioned by terms of synthesis, in our case the time of mechanical activation. {yields} The highest density and higher values of dielectric constant were achieved at the sample activated for 45 min. -- Abstract: Nickel manganite powder synthesized by calcination of a stoichiometric mixture of manganese and nickel oxide was additionally mechanically activated in a high energy planetary ball mill for 5-60 min in order to obtain a pure NiMn{sub 2}O{sub 4} phase. The as-prepared powders were uniaxially pressed into disc shape pellets and then sintered for 60 min at 1200 {sup o}C. Changes in the particle morphology induced by mechanical activation were monitored using scanning electron microscopy, while changes in powder structural characteristics were followed using X-ray powder diffraction. The ac impedance spectroscopy was performed on sintered nickel manganite samples at 25 {sup o}C, 50 {sup o}C and 80 {sup o}C. It was shown that mechanical activation intensifies transport processes causing a decrease in the average crystallites size, while longer activation times can lead to the formation of aggregates, defects and increase of lattice microstrains. The observed changes in microstructures were correlated with measured electrical properties in order to define optimal processing conditions.

  1. Antimicrobial activity and biocompatibility of Ag+- and Cu2+-doped biphasic hydroxyapatite/α-tricalcium phosphate obtained from hydrothermally synthesized Ag+- and Cu2+-doped hydroxyapatite

    International Nuclear Information System (INIS)

    Radovanović, Željko; Jokić, Bojan; Veljović, Djordje; Dimitrijević, Suzana; Kojić, Vesna; Petrović, Rada; Janaćković, Djordje

    2014-01-01

    Hydroxyapatite (HAp) powders doped with Ag + or Cu 2+ were synthesized by a hydrothermal method in order to obtain biomaterial with an antimicrobial effect. The synthesis was performed with two contents of dopant (Ag + or Cu 2+ ) by considering both the antimicrobial activities and biocompatibility of the powders. The doped HAp was annealed at 1200 °C for 2 h with the intention of investigating the influence of doping with Ag + and Cu 2+ on the creation of the biphasic HAp/α-tricalcium phosphate (HAp/α-TCP) and determining the antimicrobial activity and biocompatibility of the obtained biphasic powders. Analyses of all powders, undoped and doped HAp and HAp/α-TCP, were performed by Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), atomic absorption spectroscopy (AAS) and energy-dispersive X-ray spectroscopy (EDS). The in vitro antibacterial activities of the powders were evaluated against: Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. All powders showed good antimicrobial activity but generally the powders of doped HAp/α-TCP had more uniform results against all pathogenic microorganisms than the powders of doped HAp. In vitro biocompatibility tests, MTT and DET, were used to evaluate the biocompatibility of Ag + - and Cu 2+ -doped HAp/α-TCP with MRC-5 human fibroblast cells. These tests confirmed that powders do not have a cytotoxic effect. The HAp/α-TCP powders doped with the lower content of Ag + and Cu 2+ showed especially good biocompatibility. Antimicrobial and biocompatibility tests recommend the Ag + - and Cu 2+ -doped HAp/α-TCP as promising material for use in reconstructive surgery of bone.

  2. PbO networks composed of single crystalline nanosheets synthesized by a facile chemical precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Samberg, Joshua P. [Department of Materials Science and Engineering, North Carolina State University, 911 Partners Way, Engineering Building I, Raleigh, NC 27695-7907 (United States); Kajbafvala, Amir, E-mail: amir.kajbafvala@gmail.com [Department of Materials Science and Engineering, North Carolina State University, 911 Partners Way, Engineering Building I, Raleigh, NC 27695-7907 (United States); Koolivand, Amir [Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695 (United States)

    2014-03-01

    Graphical abstract: - Highlights: • Synthesis of PbO networks through a simple chemical precipitation route. • The synthesis method is rapid and low-cost. • Each network is composed of single crystalline PbO nanosheets. • A possible growth mechanism is proposed for synthesized PbO networks. - Abstract: For the field of energy storage, nanostructured lead oxide (PbO) shows immense potential for increased specific energy and deep discharge for lead acid battery technologies. In this work, PbO networks composed of single crystalline nanosheets were synthesized utilizing a simple, low cost and rapid chemical precipitation method. The PbO networks were prepared in a single reaction vessel from starting reagents of lead acetate dehydrate, ammonium hydroxide and deionized water. Lead acetate dehydrate was chosen as a reagent, as opposed to lead nitrate, to eliminate the possibility of nitrate contamination of the final product. X-ray diffraction (XRD) analysis, high resolution scanning electron microscopy (HRSEM) and high resolution transmission electron microscopy (HRTEM) analysis were used to characterize the synthesized PbO networks. The reproducible method described herein synthesized pure β-PbO (massicot) powders, with no byproducts. A possible formation mechanism for these PbO networks is proposed. The growth is found to proceed predominately in the 〈1 1 1〉 and 〈2 0 0〉 directions while being limited in the 〈0 1 1〉 direction.

  3. PbO networks composed of single crystalline nanosheets synthesized by a facile chemical precipitation method

    International Nuclear Information System (INIS)

    Samberg, Joshua P.; Kajbafvala, Amir; Koolivand, Amir

    2014-01-01

    Graphical abstract: - Highlights: • Synthesis of PbO networks through a simple chemical precipitation route. • The synthesis method is rapid and low-cost. • Each network is composed of single crystalline PbO nanosheets. • A possible growth mechanism is proposed for synthesized PbO networks. - Abstract: For the field of energy storage, nanostructured lead oxide (PbO) shows immense potential for increased specific energy and deep discharge for lead acid battery technologies. In this work, PbO networks composed of single crystalline nanosheets were synthesized utilizing a simple, low cost and rapid chemical precipitation method. The PbO networks were prepared in a single reaction vessel from starting reagents of lead acetate dehydrate, ammonium hydroxide and deionized water. Lead acetate dehydrate was chosen as a reagent, as opposed to lead nitrate, to eliminate the possibility of nitrate contamination of the final product. X-ray diffraction (XRD) analysis, high resolution scanning electron microscopy (HRSEM) and high resolution transmission electron microscopy (HRTEM) analysis were used to characterize the synthesized PbO networks. The reproducible method described herein synthesized pure β-PbO (massicot) powders, with no byproducts. A possible formation mechanism for these PbO networks is proposed. The growth is found to proceed predominately in the 〈1 1 1〉 and 〈2 0 0〉 directions while being limited in the 〈0 1 1〉 direction

  4. Molybdenum carbide-carbon nanocomposites synthesized from a reactive template for electrochemical hydrogen evolution

    KAUST Repository

    Alhajri, Nawal Saad

    2014-01-01

    Molybdenum carbide nanocrystals (Mo2C) with sizes ranging from 3 to 20 nm were synthesized within a carbon matrix starting from a mesoporous graphitic carbon nitride (mpg-C3N4) template with confined pores. A molybdenum carbide phase (Mo2C) with a hexagonal structure was formed using a novel synthetic method involving the reaction of a molybdenum precursor with the carbon residue originating from C3N4 under nitrogen at various temperatures. The synthesized nanocomposites were characterized using powder X-ray diffraction (XRD), temperature-programmed reaction with mass spectroscopy (MS), CHN elemental analyses, thermogravimetric analyses (TGA), nitrogen sorption, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The results indicated that the synthesized samples have different surface structures and compositions, which are accordingly expected to exhibit different electrocatalytic activities toward the hydrogen evolution reaction (HER). Electrochemical measurements demonstrated that the sample synthesized at 1323 K exhibited the highest and most stable HER current in acidic media, with an onset potential of -100 mV vs. RHE, among the samples prepared in this study. This result is attributed to the sufficiently small particle size (∼8 nm on average) and accordingly high surface area (308 m2 g-1), with less oxidized surface entrapped within the graphitized carbon matrix. © 2014 the Partner Organisations.

  5. Selective Oxidation Using Flame Aerosol Synthesized Iron and Vanadium-Doped Nano-TiO2

    Directory of Open Access Journals (Sweden)

    Zhong-Min Wang

    2011-01-01

    Full Text Available Selective photocatalytic oxidation of 1-phenyl ethanol to acetophenone using titanium dioxide (TiO2 raw and doped with Fe or V, prepared by flame aerosol deposition method, was investigated. The effects of metal doping on crystal phase and morphology of the synthesized nanostructured TiO2 were analyzed using XRD, TEM, Raman spectroscopy, and BET nitrogen adsorbed surface area measurement. The increase in the concentration of V and Fe reduced the crystalline structure and the anatase-to-rutile ratios of the synthesized TiO2. Synthesized TiO2 became fine amorphous powder as the Fe and V concentrations were increased to 3 and 5%, respectively. Doping V and Fe to TiO2 synthesized by the flame aerosol increased photocatalytic activity by 6 folds and 2.5 folds, respectively, compared to that of pure TiO2. It was found that an optimal doping concentration for Fe and V were 0.5% and 3%, respectively. The type and concentration of the metal dopants and the method used to add the dopant to the TiO2 are critical parameters for enhancing the activity of the resulting photocatalyst. The effects of solvents on the photocatalytic reaction were also investigated by using both water and acetonitrile as the reaction medium.

  6. Structural interpretation of chemically synthesized ZnO nanorod and its application in lithium ion battery

    International Nuclear Information System (INIS)

    Kundu, Samapti; Sain, Sumanta; Yoshio, Masaki; Kar, Tanusree; Gunawardhana, Nanda; Pradhan, Swapan Kumar

    2015-01-01

    Graphical abstract: - Highlights: • ZnO nanorods are synthesized at room temperature via a simple chemical route. • Growth direction of ZnO nanorods has been determined along 〈0 0 2〉. • ZnO nanorods constructed anode shows a high discharge capacity in first cycle. • It retains good reversible capacity compared to other ZnO morphologies. - Abstract: ZnO nanorods are synthesized at room temperature via a simple chemical route without using any template or capping agent and its importance is evaluated as a suitable candidate for anode material in lithium ion battery. Structural and microstructure characterizations of these nanorods are made by analyzing the X-ray diffraction data employing the Rietveld method of powder structure refinement. It reveals that the ZnO nanorods are grown up with a preferred orientation and elongated along 〈0 0 2〉. FESEM images reveal that these uniform cylindrical shaped nanorods are of different lengths and diameters. These synthesized ZnO nanorods are tested as an anode material for lithium ion batteries. The nano grain size of the ZnO rods results in less volume expansion and/or contraction during the alloying/de-alloying process and causes in good cyclability. In addition, synthesized ZnO nanorods deliver high charge/discharge capacities compared to other reported ZnO materials

  7. Structural interpretation of chemically synthesized ZnO nanorod and its application in lithium ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Samapti; Sain, Sumanta [Materials Science Division, Department of Physics, The University of Burdwan, Golapbag, Burdwan 713104, West Bengal (India); Yoshio, Masaki [Advanced Research and Education Centre, Saga University, 1341 Yoga-machi, Saga 840-0047 (Japan); Kar, Tanusree [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, West Bengal (India); Gunawardhana, Nanda, E-mail: nandagunawardhana@pdn.ac.lk [International Research Centre, Senate Building, University of Peradeniya, Peradeniya 20400 (Sri Lanka); Pradhan, Swapan Kumar, E-mail: skpradhan@phys.buruniv.ac.in [Materials Science Division, Department of Physics, The University of Burdwan, Golapbag, Burdwan 713104, West Bengal (India)

    2015-02-28

    Graphical abstract: - Highlights: • ZnO nanorods are synthesized at room temperature via a simple chemical route. • Growth direction of ZnO nanorods has been determined along 〈0 0 2〉. • ZnO nanorods constructed anode shows a high discharge capacity in first cycle. • It retains good reversible capacity compared to other ZnO morphologies. - Abstract: ZnO nanorods are synthesized at room temperature via a simple chemical route without using any template or capping agent and its importance is evaluated as a suitable candidate for anode material in lithium ion battery. Structural and microstructure characterizations of these nanorods are made by analyzing the X-ray diffraction data employing the Rietveld method of powder structure refinement. It reveals that the ZnO nanorods are grown up with a preferred orientation and elongated along 〈0 0 2〉. FESEM images reveal that these uniform cylindrical shaped nanorods are of different lengths and diameters. These synthesized ZnO nanorods are tested as an anode material for lithium ion batteries. The nano grain size of the ZnO rods results in less volume expansion and/or contraction during the alloying/de-alloying process and causes in good cyclability. In addition, synthesized ZnO nanorods deliver high charge/discharge capacities compared to other reported ZnO materials.

  8. Hydrothermally Synthesized Zinc Sulphide Microspheres for Solar Light-Driven Photocatalytic Properties

    Science.gov (United States)

    Waghadkar, Yogesh; Arbuj, Sudhir; Shinde, Manish; Ballal, Reshma; Rane, Sunit B.; Gosavi, Suresh; Fouad, H.; Chauhan, Ratna

    2018-02-01

    In this work, we reported the synthesis of zinc sulphide microspheres using the hydrothermal method. ZnS microspheres were synthesized using water, zinc acetate, thiourea and ammonia solution at 150°C for 6 h, 12 h, and 24 h. The as-synthesized ZnS powders were characterized by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and ultraviolet-visible (UV-Vis) spectroscopy. XRD indicates the cubic (major phase) as well as hexagonal (minor phase) crystalline phase with enhanced crystallinity increased gradually with more reaction time. UV-Vis spectra show the absorption peaks in the UV-Vis region for all the samples. The Tauc's plot was used to calculate the band gap energy of ZnS samples, which are found to be 3.39 eV, 3.4 eV, and 3.42 eV for the samples synthesized at reaction times of 6 h, 12 h, and 24 h, respectively. FESEM images confirm the formation of microspheres as aggregates of spherical nanoparticles. The as-synthesized ZnS microspheres have been explored for solar light-induced photo-catalytic dye degradation of methylene blue (MB), and the results confirm that such microspheres exhibit effectual photocatalytic properties.

  9. Microwave, sonochemical and combustion synthesized CuO nanostructures and their electrical and bactericidal properties

    International Nuclear Information System (INIS)

    Karunakaran, C.; Manikandan, G.; Gomathisankar, P.

    2013-01-01

    Highlights: •CuO nanoleaves synthesized by CTAB-assisted hydrothermal method. •CuO nanodiscs synthesized by CTAB-assisted sonochemical method. •Combustion synthesized CuO is highly porous. •Synthetic method and morphology influence CuO bactericidal activity. -- Abstract: Cetyltrimethylammonium bromide (CTAB)-assisted microwave synthesis of CuO provides nanoleaves and in the absence of CTAB the shape of CuO is irregular. Sonochemical synthesis of CuO using CTAB gives nanodiscs whereas irregularly shaped flake-like structure is obtained without CTAB. Combustion synthesized CuO is highly porous with innumerable large holes. CTAB does not provide any structure in combustion synthesis. Transmission electron micrographs (TEM) display the constituent nanoparticles of microwave and sonochemically synthesized CuO. The powder X-ray diffractogram (XRD) shows the sample obtained by sonochemical method in the absence of CTAB as a mixture of monoclinic CuO, cubic Cu 2 O, and orthorhombic Cu(OH) 2 . But the rest of the samples are pure CuO in monoclinic phase. The selected area electron diffractograms (SAED) of the microwave and sonochemically synthesized samples, in the presence as well as in the absence of CTAB, confirm the monoclinic phase of CuO and indicates the presence of amorphous CuO in traces. All the samples are characteristic of Fourier Transform infrared (FT-IR) Cu–O stretching frequencies. The method of synthesis and also the morphology influence the electrical properties as well as the bactericidal activity of CuO

  10. Synthesis and characterization of lead zirconate titanate powders obtained by the oxidant peroxo method

    Energy Technology Data Exchange (ETDEWEB)

    Camargo, Emerson R. [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod. Washington Luis km 235, CP 676, Sao Carlos SP, 13565-905 (Brazil)], E-mail: camargo@ufscar.br; Leite, Edson R. [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod. Washington Luis km 235, CP 676, Sao Carlos SP, 13565-905 (Brazil)], E-mail: derl@power.ufscar.br; Longo, Elson [Department of Biochemistry, Chemistry Institute of Araraquara, UNESP, Sao Paulo State University Rua Francisco Degni, CP 355 Araraquara SP, 14801-907 Brazil (Brazil)], E-mail: elson@iq.unesp.br

    2009-02-05

    Lead zirconate titanate (PbZr{sub 1-x}Ti{sub x}O{sub 3}) was synthesized by the 'oxidant peroxo method (OPM)' with 'x' between 0.25 and 0.50. Titanium metal was dissolved into a hydrogen peroxide/ammonia aqueous solution, followed by the addition of lead and zirconium nitrate solution. The amorphous precipitated precursor obtained was crystallized by heat treatment between 400 and 1000 deg. C. Images of transmission microscopy showed spherical particles with average diameter between 20 and 60 nm, and the presence of necks between particles treated at 700 deg. C. All of the unpressed powders were characterized by X-ray diffractometry and FT-Raman spectroscopy. Powder samples with 'x' up to 0.35 showed rhombohedral structure when treated at temperatures higher than 500 deg. C, and tetragonal structure when 'x' was higher than 0.40. Analysis of XRD and Raman spectroscopy of the precursor powders showed amorphous-like structures, however powders treated at 400 deg. C showed a structure identified as an intermediate pyrochlore phase, independently of the Zr and Ti mole ratio.

  11. Synthesis and characterization of lead zirconate titanate powders obtained by the oxidant peroxo method

    International Nuclear Information System (INIS)

    Camargo, Emerson R.; Leite, Edson R.; Longo, Elson

    2009-01-01

    Lead zirconate titanate (PbZr 1-x Ti x O 3 ) was synthesized by the 'oxidant peroxo method (OPM)' with 'x' between 0.25 and 0.50. Titanium metal was dissolved into a hydrogen peroxide/ammonia aqueous solution, followed by the addition of lead and zirconium nitrate solution. The amorphous precipitated precursor obtained was crystallized by heat treatment between 400 and 1000 deg. C. Images of transmission microscopy showed spherical particles with average diameter between 20 and 60 nm, and the presence of necks between particles treated at 700 deg. C. All of the unpressed powders were characterized by X-ray diffractometry and FT-Raman spectroscopy. Powder samples with 'x' up to 0.35 showed rhombohedral structure when treated at temperatures higher than 500 deg. C, and tetragonal structure when 'x' was higher than 0.40. Analysis of XRD and Raman spectroscopy of the precursor powders showed amorphous-like structures, however powders treated at 400 deg. C showed a structure identified as an intermediate pyrochlore phase, independently of the Zr and Ti mole ratio

  12. Sinteractive thoria powders derived through gel-combustion and oxalate deagglomeration - a comparison

    International Nuclear Information System (INIS)

    Ananthasivan, K.; Balakrishnan, S.; Anthonysamy, S.; Ganesan, V.; Vasudeva Rao, P.R.

    2011-01-01

    Thorium dioxide finds extensive application in the nuclear industry. Pellets of thoria are used in PHWRs for flux flattening and in FBRs as a blanket material. The development of advanced methods for the synthesis and sintering of thoria is relevant to these applications. This paper attempts to compare the properties of sinteractive nanocrystalline thoria (pure and doped with Ca 2+ and Mg 2+ ) synthesized in our laboratory through two different techniques, viz. gel-combustion and oxalate de-agglomeration. In all the investigations cited above the precursors obtained by using both the procedures were calcined in air at 1073 K. The thoria powders thus obtained were characterised for their specific surface area (SSA), X-ray crystallite size (XCS), bulk density, particle size distribution and residual carbon content. These powders were pelletised and sintered at 1473, 1673, and 1873 K. The sinterability of these powders was compared by measuring the density of the sintered pellets. A matrix density as high as 96.8 % TD (gel combustion) or 98.6 % TD (de-agglomeration) could be obtained at 1873 K, with the powders doped with 0.5 mole % calcia. (author)

  13. Doped nanocrystalline ZnO powders for non-linear resistor applications by spray pyrolysis method.

    Science.gov (United States)

    Hembram, Kaliyan; Vijay, R; Rao, Y S; Rao, T N

    2009-07-01

    Homogeneous and doped nanocrystalline ZnO powders (30-200 nm) were synthesized by spray pyrolysis technique. The spray pyrolysed powders were calcined in the temperature range of 500-750 degrees C. Formation of insulating pyrochlore phase started from 700 degrees C during the calcination itself. The calcined powders were compacted and sintered at different temperatures ranging from 900-1200 degrees C for 0.5-4 h. The densification behavior was found to be dependent on calcination temperature of the nanopowder. The resulting discs were found to have density (5.34-5.62 g/cc) in the range of 96-99% of theoretical density. The breakdown voltage value obtained for the nanopowder based non-linear resistor is 10.3 kV/cm with low leakage current density of 0.7 microA/cm2 and coefficient of nonlinearity as high as 193. The activation energy for grain growth of the doped ZnO nanopowder powders is 449.4 +/- 15 kJ/mol.

  14. [Study on moisture sorption process model and application traditional Chinese medicine extract powder].

    Science.gov (United States)

    Lin, Tingting; He, Yan; Xiao, Xiong; Yuan, Liang; Rao, Xiaoyong; Luo, Xiaojian

    2010-04-01

    Study on the moisture sorption process characteristics of traditional Chinese medicine extract powder, to establish a mathematical model, provide a new method for in-depth study for moisture sorption behavior of traditional Chinese medicine extract powder and a reference for determine the production cycle, and predict product stability. Analyzed moisture absorption process of traditional Chinese medicine extract powder by utilized the law of conservation of mass and Fick's first law to establish the double exponential absorption model, fitted the moisture absorption data and compared with other commonly used five kinds of model to estimate the double-exponential absorption model. The statistical analysis showed that the coefficient of determination (R2) of double exponential model, Weibull distribution model and first order kinetics model were large, but the residues sum of squares (RSS) and AIC values were small. Synthesized the practical application meaning, we consided that the double exponential model was more suitable for simulating the process of Chinese medicine extract powder moisture absorption. The double exponential is suitable for characterization the process of traditional Chinese medicine extract moisture absorption.

  15. Sol-gel synthesis and densification of aluminoborosilicate powders. Part 2: Densification

    Science.gov (United States)

    Bull, Jeffrey; Selvaduray, Guna; Leiser, Daniel

    1992-01-01

    Aluminoborosilicate (ABS) powders, high in alumina content, were synthesized by the sol-gel process utilizing four different methods of synthesis. The effect of these methods on the densification behavior of ABS powder compacts was studied. Five regions of shrinkage in the temperature range 25-1184 C were identified. In these regions, the greatest shrinkage occurred between the gel-to-glass transition temperature (T sub g approximately equal to 835 C) and the crystallization transformation temperature (T sub t approximately equal 900 C). The dominant mechanism of densification in this range was found to be viscous sintering. ABS powders were amorphous to x-rays up to T sub t at which a multiphasic structure crystallized. No 2Al2O3.B2O3 was found in these powders as predicted in the phase diagram. Above T sub t, densification was the result of competing mechanisms including grain growth and boria fluxed viscous sintering. Apparent activation energies for densification in each region varied according to the method of synthesis.

  16. Microstructural and electrical investigation of Cu-Ni-Cr alloys obtained by powder metallurgy method

    International Nuclear Information System (INIS)

    Carrio, Juan A.G.; Carvalhal, M.A.; Ayabe, L.M.; Monteiro, W.A.

    2009-01-01

    The aim of this work, using the powder metallurgy process, is to synthesize metallic alloys with high mechanical strength and high electric conductivity, after melting optimizing and thermal treatments. The Cu-Ni-Cr (wt%) alloys are characterized in their mechanical and electrical properties as well as the obtained microstructure. Through the process of powder metallurgy, contacts and structural parts can be obtained. The alloys elements are added to copper with the intention to improve their strength, ductility and thermal stability, without causing considerable damages in their form, electrical and thermal conductivity, and corrosion resistance. The metallic powders were mixed for a suitable time and then they were pressed in a cold uniaxial pressing (1000 kPa). Afterwards, the specimens were sintered in temperatures varying from 700 up to 800 deg C under vacuum. At last, the samples were homogenized at 550 deg C under vacuum, for special times. The comparative analysis is based on the sintered density, densification parameter, hardness, macrostructures and microstructures of the samples. The alloys were characterized by optical microscopy, X-rays powder diffraction, electrical conductivity and Vickers hardness. (author)

  17. Mixture of fuels for solution combustion synthesis of porous Fe3O4 powders

    Science.gov (United States)

    Parnianfar, H.; Masoudpanah, S. M.; Alamolhoda, S.; Fathi, H.

    2017-06-01

    The solution combustion synthesis of porous magnetite (Fe3O4) powders by a mixture of glycine and urea fuels was investigated concerning the thermodynamic aspects and powder characteristics. The adiabatic combustion temperature and combusted species were thermodynamically calculated as a function of the fuel to oxidant molar ratio (ϕ). The combustion behavior, phase evolution, porous structure and magnetic properties were characterized by thermal analysis, X-ray diffractometry, N2 adsorption-desorption, electron microscopy and vibrating sample magnetometry techniques. Nearly single phase Fe3O4 powders were synthesized by the mixture of fuels at ϕ values of 0.75 and 1. The as-combusted Fe3O4 powders at ϕ = 1 exhibited porous structure with the specific surface area of 83.4 m2/g. The highest saturation magnetization of 75.5 emu/g and the lowest coercivity of 84 Oe were achieved at ϕ = 1, due to the high purity and large crystallite size, inducing from the highest adiabatic combustion temperature.

  18. Slip casting nano-particle powders for making transparent ceramics

    Science.gov (United States)

    Kuntz, Joshua D [Livermore, CA; Soules, Thomas F [Livermore, CA; Landingham, Richard Lee [Livermore, CA; Hollingsworth, Joel P [Oakland, CA

    2011-04-12

    A method of making a transparent ceramic including the steps of providing nano-ceramic powders in a processed or unprocessed form, mixing the powders with de-ionized water, the step of mixing the powders with de-ionized water producing a slurry, sonifing the slurry to completely wet the powder and suspend the powder in the de-ionized water, separating very fine particles from the slurry, molding the slurry, and curing the slurry to produce the transparent ceramic.

  19. Methods for production of aluminium powders and their application fields

    Energy Technology Data Exchange (ETDEWEB)

    Gopienko, V.G.; Kiselev, V.P.; Zobnina, N.S. (Vsesoyuznyj Nauchno-Issledovatel' skij i Proektnyj Inst. Alyuminievoj, magnievoj i ehlektrodnoj promyshlennosti (USSR))

    1984-12-01

    Different types of powder products made of alluminium and its alloys (powder, fine powders, granules and pastes) as well as their basic physicochemical properties are briefly characterized. The principle methods for alluminium powder production are outlined: physicochemical methods, the melt spraying by compressed gas being the mostly developed among them, and physico-mechanical ones. Main application spheres for powder productions of aluminium and its alloys are reported in short.

  20. Methods for production of aluminium powders and their application fields

    International Nuclear Information System (INIS)

    Gopienko, V.G.; Kiselev, V.P.; Zobnina, N.S.

    1984-01-01

    Different types of powder products made of alluminium and its alloys (powder, fine powders, granules and pastes) as well as their basic physicochemical properties are briefly characterized. The principle methods for alluminium powder production are outlined: physicochemical methods, the melt spraying by compressed gas being the mostly developed among them, and physico-mechanical ones. Main application spheres for powder productions of aluminium and its alloys are reported in short

  1. Impact strength of sintered astaloy CrM powders

    International Nuclear Information System (INIS)

    Kazior, J.; Ploszczak, J.; Nykiel, M.; Pieczonka, T.

    2003-01-01

    In this paper results of a series of impact tests on sintered Astaloy CrM powders alloys modified by boron are presented and discussed. Boron in different forms, i.e. as elemental boron powder, boron carbide B 4 C powder or mixture of boron and carbon elemental powders, was used in different weight percentage to activate sintering of Astaloy CrM powder and to increase hardenability, with aim of increasing impact strength in view of structural applications. (author)

  2. PRODUCTION OF POROUS POWDER MATERIALS OF SPHERICAL POWDERS OF CORROSION-RESISTANT STEEL

    Directory of Open Access Journals (Sweden)

    V. N. Kovalevskij

    2012-01-01

    Full Text Available Production of porous powder materials from spherical powders of corrosion-resistant steel 12Х18н10Т with formation at low pressures 120–140 mpa in the mold with the subsequent activated sintering became possible due to increase of duration of process of spattering and formation of condensate particles (Si–C or (Mo–Si on surface.

  3. Syntheses of copper complexes of nicotinohydroxamic and ...

    African Journals Online (AJOL)

    Nicotinohydroxamic acid (NHA) and isonicotinohydroxamic acid (INHA) were synthesized, characterized by electronic and spectral studies,magnetic measurements and their pKa determined spectrophotometrically as 8.68 ± 0.02 in aqueous medium of 0.1mol dm-3 I=ionic strength. The composition of the complexes was ...

  4. SYNTHESES AND PROPERTIES OF SOME ORGANOSILANE POLYMERS

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xinghua; Robert West

    1984-01-01

    Some organosilane polymers with high molecular weights have been synthesized by cocondensation of organosilicon dihalide monomers with sodium metal in toluene. These polymers are both soluble in common solvents and meltable at lower temperatures, and can be molded, cast into films or drawn into fibers. Exposure of the solid polymers to ultraviolet light leads to degradation or crosslinking.

  5. Biological activities of synthesized silver nanoparticles

    Indian Academy of Sciences (India)

    The C. halicacabum leaf extract synthesized AgNPs efficiency were tested against different bacterial pathogens MTCC-426 Proteus vulgaris, MTCC-2453 Pseudomonas aeruginosa, MTCC-96 Staphylococcus aureus, MTCC-441 Bacillus subtilis andMTCC-735 Salmonella paratyphi, and fungal pathogens Alternaria solani ...

  6. Synthesizing chaotic maps with prescribed invariant densities

    International Nuclear Information System (INIS)

    Rogers, Alan; Shorten, Robert; Heffernan, Daniel M.

    2004-01-01

    The Inverse Frobenius-Perron Problem (IFPP) concerns the creation of discrete chaotic mappings with arbitrary invariant densities. In this Letter, we present a new and elegant solution to the IFPP, based on positive matrix theory. Our method allows chaotic maps with arbitrary piecewise-constant invariant densities, and with arbitrary mixing properties, to be synthesized

  7. Cytotoxicity of Nanoliposomal Cisplatin Coated with Synthesized ...

    African Journals Online (AJOL)

    Purpose: To evaluate the cytotoxicity of pegylated nanoliposomal cisplatin on human ovarian cancer cell line A2780CP. Methods: Synthesized methoxypolyethylene glycol (mPEG) propionaldehyde was characterized by 1Hnuclear magnetic resonance (1H-NMR) and Fourier transform infrared spectroscopy (FTIR) and used ...

  8. Biosynthesis of silver nanoparticles synthesized by Aspergillus

    Indian Academy of Sciences (India)

    In the present study, biosynthesis of silver nanoparticles and its antioxidant, antimicrobial and cytotoxic activities were investigated. Silver nanoparticles were extracellularly synthesized using Aspergillus flavus and the formation of nanoparticles was observed after 72 h of incubation. The results recorded from colour ...

  9. Structural and magnetic properties of turmeric functionalized CoFe2O4 nanocomposite powder

    International Nuclear Information System (INIS)

    Mehran, E; Farjami Shayesteh, S; Sheykhan, M

    2016-01-01

    The structural and magnetic properties of the synthesized pure and functionalized CoFe 2 O 4 magnetic nanoparticles (NPs) are studied by analyzing the results from the x-ray diffraction (XRD), transmission electron microscopy (TEM), FT–IR spectroscopy, thermogravimetry (TG), and vibrating sample magnetometer (VSM). To extract the structure and lattice parameters from the XRD analysis results, we first apply the pseudo-Voigt model function to the experimental data obtained from XRD analysis and then the Rietveld algorithm is used in order to optimize the model function to estimate the true intensity values. Our simulated intensities are in good agreement with the experimental peaks, therefore, all structural parameters such as crystallite size and lattice constant are achieved through this simulation. Magnetic analysis reveals that the synthesized functionalized NPs have a saturation magnetization almost equal to that of pure nanoparticles (PNPs). It is also found that the presence of the turmeric causes a small reduction in coercivity of the functionalized NPs in comparison with PNP. Our TGA and FTIR results show that the turmeric is bonded very well to the surface of the NPs. So it can be inferred that a nancomposite (NC) powder of turmeric and nanoparticles is produced. As an application, the anti-arsenic characteristic of turmeric makes the synthesized functionalized NPs or NC powder a good candidate for arsenic removal from polluted industrial waste water. (paper)

  10. Structural and magnetic properties of turmeric functionalized CoFe2O4 nanocomposite powder

    Science.gov (United States)

    Mehran, E.; Farjami Shayesteh, S.; Sheykhan, M.

    2016-10-01

    The structural and magnetic properties of the synthesized pure and functionalized CoFe2O4 magnetic nanoparticles (NPs) are studied by analyzing the results from the x-ray diffraction (XRD), transmission electron microscopy (TEM), FT-IR spectroscopy, thermogravimetry (TG), and vibrating sample magnetometer (VSM). To extract the structure and lattice parameters from the XRD analysis results, we first apply the pseudo-Voigt model function to the experimental data obtained from XRD analysis and then the Rietveld algorithm is used in order to optimize the model function to estimate the true intensity values. Our simulated intensities are in good agreement with the experimental peaks, therefore, all structural parameters such as crystallite size and lattice constant are achieved through this simulation. Magnetic analysis reveals that the synthesized functionalized NPs have a saturation magnetization almost equal to that of pure nanoparticles (PNPs). It is also found that the presence of the turmeric causes a small reduction in coercivity of the functionalized NPs in comparison with PNP. Our TGA and FTIR results show that the turmeric is bonded very well to the surface of the NPs. So it can be inferred that a nancomposite (NC) powder of turmeric and nanoparticles is produced. As an application, the anti-arsenic characteristic of turmeric makes the synthesized functionalized NPs or NC powder a good candidate for arsenic removal from polluted industrial waste water. Project supported by the University of Guilan and the Iran Nanotechnology Initiative Council.

  11. Facile synthesis of Curcuma longa tuber powder engineered metal nanoparticles for bioimaging applications

    Science.gov (United States)

    Sankar, Renu; Rahman, Pattanathu K. S. M.; Varunkumar, Krishnamoorthy; Anusha, Chidambaram; Kalaiarasi, Arunachalam; Shivashangari, Kanchi Subramanian; Ravikumar, Vilwanathan

    2017-02-01

    Nanomaterials based fluorescent agents are rapidly becoming significant and promising transformative tools for improving medical diagnostics for extensive in vivo imaging modalities. Compared with conventional fluorescent agents, nano-fluorescence has capabilities to improve the in vivo detection and enriched targeting efficiencies. In our laboratory we synthesized fluorescent metal nanoparticles of silver, copper and iron using Curcuma longa tuber powder by simple reduction. The physicochemical properties of the synthesized metal nanoparticles were attained using UV-visible spectrophotometry, scanning electron microscopy with EDAX spectroscopy, dynamic light scattering, Fourier-transform infrared spectroscopy and X-ray diffraction. The Curcuma longa tuber powder has one of the bioactive compound Curcumin might act as a capping agent during the synthesis of nanoparticles. The synthesized metal nanoparticles fluorescence property was confirmed by spectrofluorometry. When compared with copper and iron nanoparticles the silver nanoparticles showed high fluorescence intensity under spectrofluorometry. Moreover, in vitro cell images of the silver nanoparticles in A549 cell lines also correlated with the results of spectrofluorometry. These silver nanoparticles show inspiring cell-imaging applications. They enter into cells without any further modifications, and the fluorescence property can be utilized for fluorescence-based cell imaging applications.

  12. Lithium iron phosphate with high-rate capability synthesized through hydrothermal reaction in glucose solution

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Guangchuan; Wang, Li; Ou, Xiuqin; Zhao, Xia; Xu, Shengzhao [Institute of Power Source and Ecomaterials Science, Box 1055, Hebei University of Technology, 300130 Tianjin (China)

    2008-10-01

    Carbon-coated lithium iron phosphate (LiFePO{sub 4}/C) was hydrothermally synthesized from commercial LiOH, FeSO{sub 4} and H{sub 3}PO{sub 4} as raw materials and glucose as carbon precursor in aqueous solution at 180 C for 6 h followed by being fired at 750 C for 6 h. The samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and constant current charge-discharge cycling test. The results show that the synthesized powders are in situ coated with carbon precursor produced from glucose. At ambient temperature (25{+-}2 C), the specific discharge capacities are 154 mAh g{sup -1} at 0.2C and 136 mAh g{sup -1} at 5 C rate, and the cycling capacity retention rate reaches 98% over 90 cycles. The excellent electrochemical performance can be correlated with the in situ formation of carbon precursor/carbon, thus leading to the even distribution of carbon and the enhancement of conductibility of individual grains. (author)

  13. Characterization of γ- Al2O3 nanopowders synthesized by Co-precipitation method

    International Nuclear Information System (INIS)

    Jbara, Ahmed S.; Othaman, Zulkafli; Ati, Ali A.; Saeed, M.A.

    2017-01-01

    Co-precipitation technique has been used to synthesize gamma-Al 2 O 3 (γ-Al 2 O 3 ) nanopowders under annealing temperature effect. The crystalline phase and purity for the prepared powder were characterized by different spectroscopy techniques. XRD analysis confirms the gamma phase of alumina nanopowders with particle diameter ranging from 6 to 24 nm, which confirms the quantum dots formation, which is also supported by the BET measurement. The surface area of the prepared nanopowders is in the range of 109–367 m 2 /g. Morphology analysis indicates that γ-Al 2 O 3 nanopowders are consisted of grains almost spherical in shape. Some agglomeration of nanoparticles occurs, which become more regular hexagonal shaped with the increasing annealing temperature. The small nanoparticles size and the high surface area from a simple procedure for preparing γ-Al 2 O 3 may make it more suitable for use as an adsorbent for malachite green. - Highlights: • Co-precipitation technique is used to synthesize gamma- Al 2 O 3 nanopowders. • Pure gamma- Al 2 O 3 phase was obtained having maximum nanoparticle size is 24 nm. • The quantum dots were formed inside powder. • High surface area of nanopowders at the low annealing temperature. • Increasing annealing temperature causes the hexagonal agglomeration shape.

  14. Internal Friction Angle of Metal Powders

    Directory of Open Access Journals (Sweden)

    Jiri Zegzulka

    2018-04-01

    Full Text Available Metal powders are components with multidisciplinary usage as their application is very broad. Their consistent characterization across all disciplines is important for ensuring repeatable and trouble-free processes. Ten metal powders were tested in the study. In all cases, the particle size distribution and morphology (scanning electron microscope—SEM photos were determined. The aim of this work was to inspect the flow behavior of metal powders through another measured characteristic, namely the angle of internal friction. The measured values of the effective internal friction angle in the range 28.6–32.9°, together with the spherical particle shape and the particle size distribution, revealed the likely dominant mode of the metal particle transfer mechanism for stainless steel 316L, zinc and aluminum powder. This third piston flow mechanism is described and illustrated in detail. The angle of internal friction is mentioned as another suitable parameter for the characterization of metal powders, not only for the relative simplicity of the determination but also for gaining insight into the method of the movement of individual particles during the flow.

  15. Development and applications of ultrafine aluminium powders

    International Nuclear Information System (INIS)

    Kearns, Martin

    2004-01-01

    Over the last 20 years or so, a variety of new technologies has been developed to produce sub-micron powders. Among the products attracting interest is nanoaluminium which is being evaluated in specialist propulsion and exothermic end-uses. This paper examines the advances made in 'nanopowder' production in the context of the existing aluminium powder industry where finest commercial grades have a median size of ∼6 μm (one or two orders of magnitude coarser than nanopowders) and which today supplies the markets being targeted by nanopowders with coarser, but effective products. Are there genuine market opportunities for nanoaluminium and if so, how will they be produced? One the one hand there are the novel nanopowder production methods which are high yielding but generally slow and costly, while on the other, there is the very fine fraction from conventional atomising routes which generate a very low yield of sub-micron powder but which nevertheless can translate into a meaningful rate as part of the bulk production. Can conventional routes ever hope to make sufficient volumes of nanopowders cost effectively and which will be the favoured routes in future? Moreover, what of the 'ultrafine' size range (∼0.5-5 μm) which is of more immediate potential interest to today's powder users. This paper seeks to identify the near term opportunities for application of low volume/high value ultrafine and nano powders

  16. Effect of silver addition on the properties of combustion synthesized nanocrystalline LiCoO2

    International Nuclear Information System (INIS)

    Ghosh, Paromita; Mahanty, S.; Basu, R.N.

    2008-01-01

    Nanocrystalline (∼50 nm) LiCoO 2 powders containing 0-10 mol% of Ag have been prepared by combustion synthesis using citrate-nitrate combustion route. Thermal analyses show a sharp decomposition of the gel at ∼177 deg. C for pristine LiCoO 2 . With addition of silver, the decomposition becomes sluggish and it completes only above 430 deg. C. X-ray powder diffraction analyses show an increase in lattice parameter, c, with increasing Ag content suggesting the occupation of Ag within LiCoO 2 interlayer spacings. Transmission electron microscopy indicates diffusion of Ag into LiCoO 2 grains. It has been observed that adding 1.0 mol% silver increases the room temperature electrical conductivity by more than two orders of magnitude (1.5 x 10 -3 S cm -1 ). Galvanostatic charge-discharge profiles of coin cells fabricated with the synthesized powders show a two-fold enhancement in the discharge capacity for 1.0 mol% Ag-added LiCoO 2 cathode (140 mAh g -1 ) compared to that for pristine LiCoO 2 (70 mAh g -1 )

  17. Si/C composite lithium-ion battery anodes synthesized using silicon nanoparticles from porous silicon

    International Nuclear Information System (INIS)

    Park, Jung-Bae; Lee, Kwan-Hee; Jeon, Young-Jun; Lim, Sung-Hwan; Lee, Sung-Man

    2014-01-01

    The synthesis of Si nanoparticles by ultrasonication processing of porous Si powder and a novel method for preparing a high-capacity Si/C composite using this technique is reported. The porous Si powder is prepared by selectively etching the silicide phase of a Ti 24 Si 76 alloy consisting of Si and silicide phases. The particle size of the nanocrystalline Si is determined by the crystallite size of the Si and silicide phases in the alloy powder. Ultrasonication of the porous Si obtained from the mechanically alloyed Ti 24 Si 76 alloy generates nanocrystalline Si particles of size about 5 nm. Growth of the Si and silicide phases in the alloy is induced by annealing of the mechanically alloyed sample, with a consequent increase in the size of the Si particles obtained after ultrasonication. Application of the ultrasonication process to the fabrication of Si/C composite anode materials generates nanometer-scale Si particles in situ that are distributed in the matrix. Analysis of the phases obtained and evaluation of the distribution of the nanometer-scale Si particles in the composites via XRD/TEM measurements show that the nanometer-scale Si particles are effectively synthesized and uniformly distributed in the carbon matrix, leading to enhanced electrochemical performance of the Si/C composites

  18. Metallic and Ceramic Material Development Research

    Science.gov (United States)

    2010-05-01

    and (3) Meta- Kaolin ................94 38. Thermal Expansion Properties of the Cr2O3-ZrW2O8 Composite...were evaluated using X-ray diffraction (XRD), X-ray Fluorescence (XRF), SEM, and Energy Dispersive Spectroscopy (EDS) [16]. 3.1.5. Elastic and...oxidation product could be detected between uncoated and coated fibers using transmission electron microscopy and energy- dispersive spectroscopy

  19. Biomimetic synthesis of modified calcium phosphate fine powders and their in vitro studies

    Energy Technology Data Exchange (ETDEWEB)

    Gergulova, R., E-mail: rumigg@yahoo.com; Tepavitcharova, S., E-mail: rumigg@yahoo.com; Rabadjieva, D., E-mail: rumigg@yahoo.com; Sezanova, K., E-mail: rumigg@yahoo.com; Ilieva, R., E-mail: rumigg@yahoo.com [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 11, 1113 Sofia (Bulgaria); Alexandrova, R.; Andonova-Lilova, B. [Institute of Experimental Morphology, Pathology and Anthropology with Museum, BAS, Acad. G. Bonchev Str., Bl. 25, Sofia (Bulgaria)

    2013-12-16

    Biomimetic approach and subsequent high-temperature treatment were used to synthesize ion modified calcium phosphate fine powders. Thus, using Simulated Body Fluid (SBF) as an ion modifier, a bi-phase mixture of ion modified β-tricalcium phosphate and hydroxyapatite (β-TCP + HA) was prepared. The use of SBF electrolyte solution enriched with Mg{sup 2+} or Zn{sup 2+} yielded monophase β-tricalcium phosphate additionally modified with Mg{sup 2+} or Zn{sup 2+} (Mg-β-TCP or Zn-β-TCP). The in vitro behavior of the prepared powders on cell viability and proliferation of murine BALB/c 3T3 fibroblasts and of human Lep 3 cells was studied by MTT test assays and Mosmann method after 72 h incubation. The relative cell viability was calculated.

  20. Sol-gel synthesis and characterizations of crystalline NaGd(WO4)2 powder for anisotropic transparent ceramic laser application

    Science.gov (United States)

    Durairajan, A.; Thangaraju, D.; Balaji, D.; Moorthy Babu, S.

    2013-02-01

    NaGd(WO4)2 powders were synthesized at different pH (3.5, 4.5, 5.5, 6.5 and 7.5) values by conventional Pechini method. Sodium and gadolinium nitrate salts and ammonium paratungstate are used as starting precursors. Metal cations were chelated by citric acid and individual citrates were bound together with ethylene glycol. Synthesized gel was analyzed using differential thermal analysis (DTA), thermo gravimetric (TG) and FT-IR spectroscopy to understand the degradation of gel and formation of metal citrates. Calcined powders (250, 600, 700 and 800 °C) were characterized by powder XRD, FT-IR, Raman and FE-SEM analysis. The temperature dependent phase formation was examined by powder XRD. The morphological changes at different pH derived powders were observed with FE-SEM micrographs. Stepwise organic liberation with respect to temperature and presence of carbon content in the pre-fired powder were analyzed using FT-IR analysis. Raman spectrum reveals disordered tungstate vibrations in the NGW matrix.

  1. Role of powder preparation route on microstructure and mechanical properties of Al-TiB2 composites fabricated by accumulative roll bonding (ARB)

    International Nuclear Information System (INIS)

    Askarpour, M.; Sadeghian, Z.; Reihanian, M.

    2016-01-01

    Accumulative roll bonding (ARB) was conducted up to seven cycles to fabricate Al-TiB 2 particulate metal matrix composites. The reinforcing particles were prepared and used in three different processing conditions: as-received TiB 2 , mixed TiB 2 -Al and in-situ synthesized TiB 2 -Al. The mixed TiB 2 -Al powder was produced by milling of TiB 2 with Al powder and in-situ synthesized TiB 2 -Al powder was prepared by mechanical alloying (MA) through inducing TiB 2 particles in the Al with various composition of 10, 20 and 30 wt% Al. Transmission electron microscope (TEM) and scanning electron microscope (SEM) were used to evaluate the microstructure of the produced composites. The composite obtained from the in-situ TiB 2 -Al powder showed the most uniform distribution of particles and exhibited the highest tensile strength of about 177 MPa in comparison with the composites reinforced with the as-received TiB 2 (156 MPa) and mixed TiB 2 -Al powder (160 MPa). After seven ARB cycles, an ultra-fine grained structure with the average size of about 300 nm was obtained in the composite reinforced with in-situ TiB 2 -Al powder. The appearance of dimples in tensile fracture surfaces revealed a ductile-type fracture in the produced composites.

  2. Role of powder preparation route on microstructure and mechanical properties of Al-TiB{sub 2} composites fabricated by accumulative roll bonding (ARB)

    Energy Technology Data Exchange (ETDEWEB)

    Askarpour, M.; Sadeghian, Z., E-mail: z.sadeghian@scu.ac.ir; Reihanian, M.

    2016-11-20

    Accumulative roll bonding (ARB) was conducted up to seven cycles to fabricate Al-TiB{sub 2} particulate metal matrix composites. The reinforcing particles were prepared and used in three different processing conditions: as-received TiB{sub 2}, mixed TiB{sub 2}-Al and in-situ synthesized TiB{sub 2}-Al. The mixed TiB{sub 2}-Al powder was produced by milling of TiB{sub 2} with Al powder and in-situ synthesized TiB{sub 2}-Al powder was prepared by mechanical alloying (MA) through inducing TiB{sub 2} particles in the Al with various composition of 10, 20 and 30 wt% Al. Transmission electron microscope (TEM) and scanning electron microscope (SEM) were used to evaluate the microstructure of the produced composites. The composite obtained from the in-situ TiB{sub 2}-Al powder showed the most uniform distribution of particles and exhibited the highest tensile strength of about 177 MPa in comparison with the composites reinforced with the as-received TiB{sub 2} (156 MPa) and mixed TiB{sub 2}-Al powder (160 MPa). After seven ARB cycles, an ultra-fine grained structure with the average size of about 300 nm was obtained in the composite reinforced with in-situ TiB{sub 2}-Al powder. The appearance of dimples in tensile fracture surfaces revealed a ductile-type fracture in the produced composites.

  3. Synthesis and characterization of scandia ceria stabilized zirconia powders prepared by polymeric precursor method for integration into anode-supported solid oxide fuel cells

    Science.gov (United States)

    Tu, Hengyong; Liu, Xin; Yu, Qingchun

    2011-03-01

    Scandia ceria stabilized zirconia (10Sc1CeSZ) powders are synthesized by polymeric precursor method for use as the electrolyte of anode-supported solid oxide fuel cell (SOFC). The synthesized powders are characterized in terms of crystalline structure, particle shape and size distribution by X-ray diffraction (XRD), transmission electron microscopy (TEM) and photon correlation spectroscopy (PCS). 10Sc1CeSZ electrolyte films are deposited on green anode substrate by screen-printing method. Effects of 10Sc1CeSZ powder characteristics on sintered films are investigated regarding the integration process for application as the electrolytes in anode-supported SOFCs. It is found that the 10Sc1CeSZ films made from nano-sized powders with average size of 655 nm are very porous with many open pores. In comparison, the 10Sc1CeSZ films made from micron-sized powders with average size of 2.5 μm, which are obtained by calcination of nano-sized powders at higher temperatures, are much denser with a few closed pinholes. The cell performances are 911 mW cm-2 at the current density of 1.25 A cm-2 and 800 °C by application of Ce0.8Gd0.2O2 (CGO) barrier layer and La0.6Sr0.4CoO3 (LSC) cathode.

  4. Preparation of TiC/W core–shell structured powders by one-step activation and chemical reduction process

    International Nuclear Information System (INIS)

    Ding, Xiao-Yu; Luo, Lai-Ma; Huang, Li-Mei; Luo, Guang-Nan; Zhu, Xiao-Yong; Cheng, Ji-Gui; Wu, Yu-Cheng

    2015-01-01

    Highlights: • A novel wet chemical method was used to prepare TiC/W core–shell structure powders. • TiC nanoparticles were well-encapsulated by W shells. • TiC phase was present in the interior of tungsten grains. - Abstract: In the present study, one-step activation and chemical reduction process as a novel wet-chemical route was performed for the preparation of TiC/W core–shell structured ultra-fine powders. The XRD, FE-SEM, TEM and EDS results demonstrated that the as-synthesized powders are of high purity and uniform with a diameter of approximately 500 nm. It is also found that the TiC nanoparticles were well-encapsulated by W shells. Such a unique process suggests a new method for preparing X/W (X refers the water-insoluble nanoparticles) core–shell nanoparticles with different cores

  5. Direct synthesis of nano-sized glass powders with spherical shape by RF (radio frequency) thermal plasma

    International Nuclear Information System (INIS)

    Seo, J.H.; Kim, J.S.; Lee, M.Y.; Ju, W.T.; Nam, I.T.

    2011-01-01

    A new route for obtaining very small, spheroid glass powders is demonstrated using an RF (radio frequency) thermal plasma system. During the process, four kinds of chemicals, here SiO 2 , B 2 O 3 , BaCO 3 , and K 2 CO 3 , were mixed at pre-set weight ratios, spray-dried, calcined at 250 deg. C for 3 h, and crushed into fragments. Then, they were successfully reformed into nano-sized amorphous powders (< 200 nm) with spherical shape by injecting them along the centerline of an RF thermal plasma reactor at ∼ 24 kW. The as-synthesized powders show negligible (< 1%) composition changes when compared with the injected precursors of raw material compounds.

  6. Sol-gel synthesis and structure of La2O3–CoO–SiO2 powders

    Directory of Open Access Journals (Sweden)

    Lachezar Radev

    2008-12-01

    Full Text Available LaCoO3 powders are studied because they exhibit interesting electrical, magnetic and catalytic properties. In this paper, new synthesized La2O3-CoO-SiO2 powders with different quantity of silica were prepared via solgel method in aqua media, starting from metal nitrates with different chelating agents. The relation between the reaction in solution, crystallization pathway and morphology were discussed. In LaCoO3-SiO2 powders, depending on the content of SiO2 and the treatment temperature (700–1100°C, different crystalline phases (LaCoO3, Co2SiO4 and La9.31(SiO46O2 were observed with the crystallite sizes ranging from 50 to 100 nm. It was proved that chemical composition and nature of used additives has influence on the phase formation and structure of obtained nanomaterials.

  7. Plasma deposition by discharge in powder

    International Nuclear Information System (INIS)

    El-Gamal, H.A.; El-Tayeb, H.A.; Abd El-Moniem, M.; Masoud, M.M.

    2000-01-01

    Different types of material powders have been fed to the breach of a coaxial discharge. The coaxial discharge is powered from a 46.26 mu F, 24 KV capacitor bank. When the discharge takes place at the breach, the powder is heated and ionized to form a sheath of its material. The plasma sheath is ejected from the discharge zone with high velocity. The plasma sheath material is deposited on a glass substrate. It has been found from scanning electron microscope (SEM) analysis that the deposited material is almost homogenous for ceramic and graphite powders. The grain size is estimated to be the order of few microns. To measure the deposited material thickness the microdensitometer and a suitable arrangement of a laser interferometer and an optical microscope are used. It has also been found that deposited material thickness depends on the discharge number of shots and the capacitor bank energy

  8. Synthesis of yttria powders by electrospray pyrolysis

    International Nuclear Information System (INIS)

    Rulison, A.J.; Flagan, R.C.

    1994-01-01

    Electrospray atomization of high-concentration (∼400 g/L) chemical precursor solutions was applied to the synthesis of yttria powders. Conditions were found which led to high-quality powders, composed of dense, spheroidal, submicrometer, and nanocrystalline oxide particles. The precursor solutions were hydrated yttrium nitrates dissolved in n-propyl alcohol at concentrations ranging from 44.1 to 455 g/L. Electrospray atomization produced submicrometer precursor droplets which were dispersed in air and carried through an electric furnace for thermal decomposition at 500 C for several seconds residence time. X-ray powder diffraction patterns indicated the expected cubic phase. Transmission electron micrographs showed that the particle structure varied with solution composition, ranging from hollow, inflated spheres for 6-hydrated nitrates to dense spheroids for 5-hydrated nitrates. The use of 6-hydrated nitrates in the solutions appeared to form particle surfaces which were impermeable to alcohol vapor evolved during thermal decomposition, leading to hollow, inflated spheres

  9. Red man syndrome caused by vancomycin powder.

    Science.gov (United States)

    Nagahama, Yasunori; VanBeek, Marta J; Greenlee, Jeremy D W

    2018-04-01

    Red man syndrome (RMS) is a well-known hypersensitivity reaction caused by intravenous administration of vancomycin, with symptoms ranging from flushing, erythematous rash, pruritus, mild to profound hypotension, and even cardiac arrest. RMS has not previously been described from local application of vancomycin powder in a surgical wound, a technique increasingly utilized for infection prophylaxis in many surgical disciplines including neurosurgery. We describe the first reported case of RMS as a result of local intra-wound application of vancomycin powder for infection prophylaxis. A 73-year-old male with a history of Parkinson's disease underwent 2-stage deep brain stimulation implantation surgeries. Vancomycin powder was applied locally in the surgical wounds for infection prophylaxis during both of the surgeries. The patient developed a well-demarcated, geometric erythematous pruritic rash following the second surgery that was clinically diagnosed as RMS and resolved without sequelae. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. Ultrasonic assisted hot metal powder compaction.

    Science.gov (United States)

    Abedini, Rezvan; Abdullah, Amir; Alizadeh, Yunes

    2017-09-01

    Hot pressing of metal powders is used in production of parts with similar properties to wrought materials. During hot pressing processes, particle rearrangement, plastic deformation, creep, and diffusion are of the most effective powder densification mechanisms. Applying ultrasonic vibration is thought to result in great rates of densification and therefore higher efficiency of the process is expected. This paper deals with the effects of power ultrasonic on the densification of AA1100 aluminum powder under constant applied stress. The effects of particle size and process temperature on the densification behavior are discussed. The results show that applying ultrasonic vibration leads to an improved homogeneity and a higher relative density. Also, it is found that the effect of ultrasonic vibration is greater for finer particles. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Correlating particle hardness with powder compaction performance.

    Science.gov (United States)

    Cao, Xiaoping; Morganti, Mikayla; Hancock, Bruno C; Masterson, Victoria M

    2010-10-01

    Assessing particle mechanical properties of pharmaceutical materials quickly and with little material can be very important to early stages of pharmaceutical research. In this study, a wide range of pharmaceutical materials were studied using atomic force microscopy (AFM) nanoindentation. A significant amount of particle hardness and elastic modulus data were provided. Moreover, powder compact mechanical properties of these materials were investigated in order to build correlation between the particle hardness and powder compaction performance. It was found that the materials with very low or high particle hardness most likely exhibit poor compaction performance while the materials with medium particle hardness usually have good compaction behavior. Additionally, the results from this study enriched Hiestand's special case concept on particle hardness and powder compaction performance. This study suggests that the use of AFM nanoindentation can help to screen mechanical properties of pharmaceutical materials at early development stages of pharmaceutical research.

  12. Proportioning of U3O8 powder

    International Nuclear Information System (INIS)

    Cermak, V.; Markvart, M.; Novy, P.; Vanka, M.

    1989-01-01

    The tests are briefly described or proportioning U 3 O 8 powder of a granulometric grain size range of 0-160 μm using a vertical screw, a horizontal dual screw and a vibration dispenser with a view to proportioning very fine U 3 O 8 powder fractions produced in the oxidation of UO 2 fuel pellets. In the tests, the evenness of proportioning was assessed by the percentage value of the proportioning rate spread measured at one-minute intervals at a proportioning rate of 1-3 kg/h. In feeding the U 3 O 3 in a flame fluorator, it is advantageous to monitor the continuity of the powder column being proportioned and to assess it radiometrically by the value of the proportioning rate spread at very short intervals (0.1 s). (author). 10 figs., 1 tab., 12 refs

  13. Induction investigations powder ittrium-barium cuprite

    International Nuclear Information System (INIS)

    Savchenko, O.V.; Savchenko, O.Ya.

    1993-01-01

    Behavior of magnetic moment of the YBa 2 Cu 3 O 7 powder has been studied in the pulsed and alternating magnetic field with the amplitude from 40 A/m to 4 kA/m at the temperature of liquid nitrogen boiling. The complex behavior of the magnetic moment is ascribed to the presence in the powder of two current carrying phases with the limit current densities differing by more than an order of magnitude. The magnetic field after-effect of several tens of kA/m on the powder results in the limit current density of the phase with reduced current density diminishes still further almost by an order of magnitude after the power exposure in the magnetic field. The direct magnetic field of several tens of kA/m practically completely suppresses the current in the phase with the reduced current density and noticeably reduces the fraction of the other phase

  14. Transport device for nuclear fuel powder

    International Nuclear Information System (INIS)

    Adelmann, M.

    1987-01-01

    The transport device for nuclear fuel powder, which does not disintegrate during transport, has a transport pipe which starts with its entry end from the floor or a closed container and opens with its outlet end at the top into a closed separation container connect via a powder filter to a suction pump. By alternate regular opening and closing of a first control valve for transport gas fitted to a transport pipe to a supply duct and a second control valve for transport gas fitted to the container to an additional supply duct, alternating plugs of nuclear fuel powder and transport gas cushions are formed and are transported to the outlet end of the transport pipe. (orig./HP) [de

  15. Study on Quality Aggregate Construction Powder

    International Nuclear Information System (INIS)

    Myat Ko; Kyaw Naing; Thazin Lwin; Khin Mar Tun

    2008-03-01

    This research work deals with a view to promote cement replacement materials i-e aggregate construction powder, also known as building powder or construction powder . It has been used as lime substituent in construction work in Myanmar since 1990's. It is mixed with other construction materials such as cement, sand, etc. and used in plastering, tiling, arranging bricks and smoothing the face of the buildings.This work also deals with some aspects in physical properties of four different aggregate construction powder samples such as Moe Hein, Man Thiri, Shwe Taung and Kyauk Sue. In addition, these four different samples were characterized by using spectroscopic methods such as ED-XRF, AAS, FT-IR and XRD. In support of the finding by the analytical assays of Moe Hein aggregate construction powder, it indicated the percent composition of the presence of SiO2 12.13%, Al2O3 7.40%, Fe2O3 0.94%, CaO 41.00%,MgO 1.50% total sulphur 1.15%, chloride 1.49%, carbonate 43.63% and sulphate 3.44%. The analytical assays of Sin Min cement, Kyant cement, brick powder and pozzolan were also carried out in this research work. The mixing between various ratios of Moe Hein and Kyant cement as well as Sin Min II cement were done and their mechanical strengths such as setting time, tensile strength and compressive strength of each sample were studied. The quality of mixing ratio 50:50 of Moe Hein and Kyant cement was found to be comparable to the ASTM standard type II Protland cement which is for general use.

  16. Morphology study of refractory carbide powders

    International Nuclear Information System (INIS)

    Vavrda, J.; Blazhikova, Ya.

    1982-01-01

    Refractory carbides were investigated using JSM-U3 electron microscope of Joelco company at 27 KV accelerating voltage. Some photographs of each powder were taken with different enlargements to characterise the sample upon the whole. It was shown that morphological and especially topographic study of powders enables to learn their past history (way of fabrication and treatment). The presence of steps of compact particle fractures and cracks is accompanied by occurence of fine dispersion of carbides subjected to machining after facrication. On the contrary, the character of crystallographic surfaces and features of surface growth testify to the way of crystallization

  17. Menu Proposal to Use Powdered Agar

    OpenAIRE

    土屋, ひろ子; 嶋村, 桃子; 小松, 沙霧

    2015-01-01

    The author was involved in the development of the menu items that might be sold at “Taisho Village”, a theme park. Requirements in the menu development were that cooking should be simple as it starts cooking after receiving orders and it should have attractive appearances. Powdered agar has advantages over rod-shaped or string-shaped agar, with easiness of handling such as its ready solubility in water and no need to wash, rehydrate or strain. Because powdered agar is easy to use in cooking,...

  18. In-house characterization of protein powder

    DEFF Research Database (Denmark)

    Hartmann, Christian Grundahl; Harris, Pernille; Ståhl, Kenny

    2011-01-01

    . For safe identification of the crystal form the experimental patterns have to be compared with patterns calculated from known crystal structures. Very good agreement with Protein Data Bank data was obtained after including corrections for background, unit cell parameters, disordered bulk......Collecting protein powder diffraction data on standard in-house powder diffractometers requires careful handling of the samples. Specially designed sample holders combined with optimized collimation were found to be the key factors in improving the data quality and reducing the data collection time......-solvent, and geometric factors. The data collection and correction procedures were demonstrated by the identification of three different crystal forms of insulin....

  19. Peculiarities of powder brittle media compaction

    International Nuclear Information System (INIS)

    Perel'nam, V.E.; Aristarkhov, A.I.

    1981-01-01

    The paper is concerned with theoretical and practical aspects of the compaction process for powders of almost unstrained materials. Consideration from the standpoint of compressible body strain mechanics shows that such porous media may have a certain ''threshold'' density. Ductile characteristics of the porous material compacted up to this extent are identical with properties of compacrat bodies, i.e. there is a theoretically substantiated ban on a possibility of their further compaction without changing the state of the powder particle material. Theoretical conclusions are confirmed by results of experimental studies in compaction of titanium- containing ceramics [ru

  20. Hypolipidemic effects of fenugreek seed powder

    Directory of Open Access Journals (Sweden)

    Abu Saleh M. Moosa, Mamun Ur Rashid, A.Z.S. Asadi, Nazma Ara, M. Mojib Uddin and A. Ferdaus

    2006-12-01

    Full Text Available Effects of fenugreek (Trigonella foenugraecum Linn on serum lipid profile in hypercholesteremic type 2 diabetic patients were studied. Administration of fenugreek seed powder of 25 gm orally twice daily for 3 weeks and 6 weeks produces significant (P<0.001 reduction of serum total cholesterol, triacylglyceride and LDL-cholesterol in hypercholesteremic group but the change of serum HDL-cholesterol was not significant. On other hand, changes of lipid profile in hypercholesteremic type 2 diabetic patients without fenugreek were not significant (P<0.001. The present study suggests that fenugreek seed powder would be considered as effective agent for lipid lowering purposes.

  1. Extinguisher powder for liquid metal fires

    Energy Technology Data Exchange (ETDEWEB)

    Menzenhauer, P; Ochs, G [Kernforschungszentrum Karlsruhe G.m.b.H. (Germany, F.R.). Inst. fuer Reaktorentwicklung

    1978-11-01

    The extinguisher introduced here based on graphite exhibited considerably improved extinguishing properties compared to other extinguishing powders. It has no aggressive properties, is, as for as could be tested in the short time available, non-hygroscopic and thus very easy to remove after extinguishing and cooling of the fire. The amount of extinguisher necessary is only a fraction of the amounts needed of other common powders. Storage is no problem and nerely a small storage amount is required. This extinguisher is excellently suitable for fighting sodium surface fires.

  2. Extinguisher powder for liquid metal fires

    International Nuclear Information System (INIS)

    Menzenhauer, P.; Ochs, G.

    1978-01-01

    The extinguisher introduced here based on graphite exhibited considerably improved extinguishing properties compared to other extinguishing powders. It has no aggressive properties, is, as for as could be tested in the short time available, non-hygroscopic and thus very easy to remove after extinguishing and cooling of the fire. The amount of extinguisher necessary is only a fraction of the amounts needed of other common powders. Storage is no problem and nerely a small storage amount is required. This extinguisher is excellently suitable for fighting sodium surface fires. (orig./HP) [de

  3. Fabricating solid carbon porous electrodes from powders

    Science.gov (United States)

    Kaschmitter, James L.; Tran, Tri D.; Feikert, John H.; Mayer, Steven T.

    1997-01-01

    Fabrication of conductive solid porous carbon electrodes for use in batteries, double layer capacitors, fuel cells, capacitive dionization, and waste treatment. Electrodes fabricated from low surface area (Electrodes having a higher surface area, fabricated from powdered carbon blacks, such as carbon aerogel powder, carbon aerogel microspheres, activated carbons, etc. yield high conductivity carbon compositives with excellent double layer capacity, and can be used in double layer capacitors, or for capacitive deionization and/or waste treatment of liquid streams. By adding metallic catalysts to be high surface area carbons, fuel cell electrodes can be produced.

  4. determination of mercury content in milk powder

    International Nuclear Information System (INIS)

    Jovchev, M.; Grigorov, T.; Apostolov, D.

    1985-01-01

    Four samples of humanized full cream cow milk powder of Bulgarian origin for new-born, sucklings, small children and soured milk powder were activated for 18-24 h in a neutron flux of 5.10 12 , resp. 2.10 13 n/cm 2 .sec in quartz ampules. The samples were activated without preliminary lyophilization, thus avoiding possible mistakes from mercury losses. Ag-110m, being eliminated in the amalgam, was not an obstacle to the mercury determination. The results obtained for the mercury content are in the same order as in other investigations and many times lower than the admissible norm for foodstuffs - 50 ppb

  5. The irradiation preservation technology for chili powders

    International Nuclear Information System (INIS)

    Chen Qixun; Xu Peishu; Wang Xiuying; Liu Shupei

    1988-01-01

    The chili is harvested in hot season, thus it may be large in number of bacterium contamination and liable to be molded in storage; and difficult to be kept in powder form. However, by irradiating the chili powder with Co-γray to 5 dGy within a proper package, total number of bacteria will drop by a factor of 10 4 and colour bacillus less than 30. Its colour, fragrance, taste and appearance are not affected for one year after irradiation if the package is good

  6. Desensitizing nano powders to electrostatic discharge ignition

    International Nuclear Information System (INIS)

    Steelman, Ryan; Daniels, Michael A.

    2015-01-01

    Electrostatic discharge (ESD) is a main cause for ignition in powder media ranging from grain silos to fireworks. Nanoscale particles are orders of magnitude more ESD ignition sensitive than their micron scale counterparts. This study shows that at least 13 vol. % carbon nanotubes (CNT) added to nano-aluminum and nano-copper oxide particles (nAl + CuO) eliminates ESD ignition sensitivity. The CNT act as a conduit for electric energy and directs electric charge through the powder to desensitize the reactive mixture to ignition. For nanoparticles, the required CNT concentration for desensitizing ESD ignition acts as a diluent to quench energy propagation.

  7. Larnite powders and larnite/silica aerogel composites as effective agents for CO{sub 2} sequestration by carbonation

    Energy Technology Data Exchange (ETDEWEB)

    Santos, A., E-mail: alberto.santos@uca.es [Departamento de Ciencias de la Tierra, Universidad de Cadiz, Puerto Real, 11510 Cadiz (Spain); Ajbary, M.; Morales-Florez, V. [Departamento de Fisica de la Materia Condensada, Universidad de Cadiz, Puerto Real, 11510 Cadiz (Spain); Kherbeche, A. [Universite Sidi Mohamed Ben Abdellah, Ecole Superieure de Technologie, Fes (Morocco); Pinero, M. [Departamento de Fisica Aplicada, Universidad de Cadiz, Puerto Real, 11510 Cadiz (Spain); Esquivias, L. [Departamento de Fisica de la Materia Condensada, Facultad de Fisica, Instituto de Ciencias de Materiales de Sevilla (CSIC), Universidad de Sevilla, 41012 Sevilla (Spain)

    2009-09-15

    This paper presents the results of the carbonation reaction of two sample types: larnite (Ca{sub 2}SiO{sub 4}) powders and larnite/silica aerogel composites, the larnite acting as an active phase in a process of direct mineral carbonation. First, larnite powders were synthesized by the reaction of colloidal silica and calcium nitrate in the presence of ethylene glycol. Then, to synthesize the composites, the surface of the larnite powders was chemically modified with 3-aminopropyltriethoxysilane (APTES), and later this mixture was added to a silica sol previously prepared from tetraethylorthosilicate (TEOS). The resulting humid gel was dried in an autoclave under supercritical conditions for the ethanol. The textures and chemical compositions of the powders and composites were characterized.The carbonation reaction of both types of samples was evaluated by means of X-ray diffraction and thermogravimetric analysis. Both techniques confirm the high efficiency of the reaction at room temperature and atmospheric pressure. A complete transformation of the silicate into carbonate resulted after submitting the samples to a flow of pure CO{sub 2} for 15 min. This indicates that for this reaction time, 1 t of larnite could eliminate about 550 kg of CO{sub 2}. The grain size, porosity, and specific surface area are the factors controlling the reaction.

  8. Spheroidization of glass powders for glass ionomer cements.

    Science.gov (United States)

    Gu, Y W; Yap, A U J; Cheang, P; Kumar, R

    2004-08-01

    Commercial angular glass powders were spheroidized using both the flame spraying and inductively coupled radio frequency plasma spraying techniques. Spherical powders with different particle size distributions were obtained after spheroidization. The effects of spherical glass powders on the mechanical properties of glass ionomer cements (GICs) were investigated. Results showed that the particle size distribution of the glass powders had a significant influence on the mechanical properties of GICs. Powders with a bimodal particle size distribution ensured a high packing density of glass ionomer cements, giving relatively high mechanical properties of GICs. GICs prepared by flame-spheroidized powders showed low strength values due to the loss of fine particles during flame spraying, leading to a low packing density and few metal ions reacting with polyacrylic acid to form cross-linking. GICs prepared by the nano-sized powders showed low strength because of the low bulk density of the nano-sized powders and hence low powder/liquid ratio of GICs.

  9. Enzymatic synthesizing of phytosterol oleic esters.

    Science.gov (United States)

    Pan, Xinxin; Chen, Biqiang; Wang, Juan; Zhang, Xinzhi; Zhul, Biyun; Tan, Tianwei

    2012-09-01

    A method of synthesizing the phytosterol esters from oleic acid and sterols was studied, using immobilized lipase Candida sp. 99-125 as catalyst. Molar ratio (oleic acid/phytosterols), temperature, reaction period, organic solvents, catalyst, and silica-gel drier were optimized, and the result showed that 93.4% of the sterols had been esterified under the optimal synthetic condition: the molar ratio of oleic acid/phytosterol is 1:1 in 10 mL iso-octane, immobilized lipase (w, 140% of the sterols), incubated in an orbital shaker (200 rpm) at a temperature of 45 °C for 24 h. The immobilized lipase could be reused for at least 13 times with limited loss of esterification activity. The conversion still maintained up to 86.6%. Hence, this developed process for synthesizing phytosterol esters could be considered as simple and low-energy consumption compared to existing chemical processes.

  10. Syntheses and studies of organosilicon compounds

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Ren [Iowa State Univ., Ames, IA (United States)

    1999-02-12

    The syntheses of polycarbosilanes and polysilanes as silicon carbide ceramic precursors have been active research areas in the Barton Research Group. In this thesis, the work is focused on the preparation of polycarbosilanes and polysilanes as stoichiometric silicon carbide precursor polymers. The syntheses of the precursor polymers are discussed and the conversions of these precursors to silicon carbide via pyrolysis are reported. The XRD pattern and elemental analyses of the resulting silicon carbide ceramics are presented. Silicon monoxide is an important intermediate in the production of silicon metal. The existence of silicon monoxide in gap phase has been widely accepted. In the second part of this thesis, the generation of gaseous silicon monoxide in four different reactors and the reactions of gaseous silicon monoxide towards organic compounds are discussed.

  11. SYNTHESES AND CHARACTERIZATIONS OF THE CYANIDE ...

    African Journals Online (AJOL)

    2015-10-28

    (Received October 28, 2015; revised June 25, 2016) ... suggest that the Ni(II) ion is four coordinate with four cyanide-carbon atoms in ... However, there have been many studies on octahedral [M(CN)6]n- but little ... were synthesized and investigated by vibrational spectral (FT-IR and ..... Karaağaç, D.; Kürkçüoğlu, G.S. Bull.

  12. Molecular trees: from syntheses towards applications

    International Nuclear Information System (INIS)

    Ardoin, N.; Astruc, D.

    1995-01-01

    Molecular trees, also called dendrimers, arborols, cauliflowers, cascades or hyperbranched molecules, have been synthesized since their first observation in 1978 by divergent, convergent or combined methods, with various functions on the branches. The potential applications of these nanoscopic molecules are in the fields of biology (gene therapy, virus mimicking an vectorization) and molecular materials sciences (new polymers, adhesion, liquid crystals, etc). (authors). 236 refs., 6 figs., 2 tabs., 8 schemes

  13. Novel stereocontrolled syntheses of tashiromine and epitashiromine

    Directory of Open Access Journals (Sweden)

    Loránd Kiss

    2015-04-01

    Full Text Available A novel stereocontrolled approach has been developed for the syntheses of tashiromine and epitashiromine alkaloids from cyclooctene β-amino acids. The synthetic concept is based on the azetidinone opening of a bicyclic β-lactam, followed by oxidative ring opening through ring C–C double bond and reductive ring-closure reactions of the cis- or trans-cyclooctene β-amino acids.

  14. Spurious in PLL-DDS frequency synthesizers

    Czech Academy of Sciences Publication Activity Database

    Kroupa, Věnceslav František; Štursa, Jarmil

    2002-01-01

    Roč. 2, č. 1 (2002), s. 48-51 ISSN 1335-8243. [Digital Signal Processing and Multimedia Communications DSP-MCOM 2001 /5./. Košice, 27.11.2001-29.11.2001] R&D Projects: GA ČR GA102/00/0958 Institutional research plan: CEZ:AV0Z2067918 Keywords : frequency synthesizers * phase locked loops * direct digital synthesis Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  15. The crystallization of amorphous Fe2MnGe powder prepared by ball milling

    International Nuclear Information System (INIS)

    Zhang, L.; Brueck, E.; Tegus, O.; Buschow, K.H.J.; Boer, F.R. de

    2003-01-01

    We synthesized for the first time the intermetallic compound Fe 2 MnGe. To avoid preferential evaporation of volatile components we exploited mechanical alloying. Amorphous Fe 2 MnGe alloy powder was prepared by planetary ball milling elemental starting materials. The amorphous-to-crystalline transition was studied by means of differential scanning calorimetry (DSC) and X-ray diffraction (XRD). A cubic D0 3 phase is formed at low temperature and transforms to a high-temperature hexagonal D0 19 phase. The apparent activation energy was determined by means of the Kissinger method

  16. Adsorption of citrate ions on hydroxyapatite synthesized by various methods

    International Nuclear Information System (INIS)

    Skwarek, E.; Janusz, W.; Sternik, D.

    2014-01-01

    The specific adsorption of citric acid ions at hydroxyapatite interface was investigated by the means of radioisotope method ( 14 C) as a function of citric acid ions concentration, NaCl concentration and pH. Application of the hydroxyapatite has become wide in the biomaterial field as the Ca 10 (OH) 2 (PO 4 ) 6 possess biocompatibility with human hard tissue. Hydroxyapatite was synthesized using three different methods. The physical properties of the resulting powder were characterized by DTA/TG, XRD, AFM and SEM microscopy. Physicochemical qualities characterizing the electrical double layer of the hydroxyapatite/NaCl solution interface were determined. The zeta potential and the adsorption of citric acid molecule were studied as a function of pH. The point of zero charge and the isoelectric point of samples were determined. Electrical double layer parameters of hydroxyapatite/NaCl interface are influenced by a synthesis method. The points pH pzc and pH IEP for sample 1 are pH pzc 7.5 and pH IEP 3; for sample 2 pH pzc 7.05 and pH IEP 3, for sample 3 pH pzc 6.7 and pH IEP 3. Temperature has weak influence both on pure substance and with citric acid adsorbed, as derivatographic analysis has shown, and characterization of hydroxyapatite structure may be carried out by this thermal analysis. Two phenomena are responsible for citric acid adsorption: phosphate group's replacement at hydroxyapatite surface by citric ions parallel to intraspherical complexes formation. (author)

  17. Valorization of Bone Waste of Saudi Arabia by Synthesizing Hydroxyapatite.

    Science.gov (United States)

    Amna, Touseef

    2018-05-09

    At present, hydroxyapatite is being frequently used for diverse biomedical applications as it possesses excellent biocompatibility, osteoconductivity, and non-immunogenic characteristics. The aim of the present work was to recycle bone waste for synthesis of hydroxyapatite nanoparticles to be used as bone extracellular matrix. For this reason, we for the first time utilized bio-waste of cow bones of Albaha city. The residual bones were utilized for the extraction of natural bone precursor hydroxyapatite. A facile scientific technique has been used to synthesize hydroxyapatite nanoparticles through calcinations of wasted cow bones without further supplementation of chemicals/compounds. The obtained hydroxyapatite powder was ascertained using physicochemical techniques such as XRD, SEM, FTIR, and EDX. These analyses clearly show that hydroxyapatite from native cow bone wastes is biologically and physicochemically comparable to standard hydroxyapatite, commonly used for biomedical functions. The cell viability and proliferation over the prepared hydroxyapatite was confirmed with CCk-8 colorimetric assay. The morphology of the cells growing over the nano-hydroxyapatite shows that natural hydroxyapatite promotes cellular attachment and proliferation. Hence, the as-prepared nano-hydroxyapatite can be considered as cost-effective source of bone precursor hydroxyapatite for bone tissue engineering. Taking into account the projected demand for reliable bone implants, the present research work suggested using environment friendly methods to convert waste of Albaha city into nano-hydroxyapatite scaffolds. Therefore, besides being an initial step towards accomplishment of projected demands of bone implants in Saudi Arabia, our study will also help in reducing the environmental burden by recycling of bone wastes of Albaha city.

  18. Photoluminescence properties of PZT 52/48 synthesized by microwave hydrothermal method using PVA with template

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, G.F., E-mail: guilmina@hotmail.com [Instituto de Quimica, Universidade Estadual Paulista, Departamento de Bioquimica e Tecnologia Quimica, Rua Francisco Degni s/n, Quitandinha, 14800-900 Araraquara, SP (Brazil); Gasparotto, G. [Instituto de Quimica, Universidade Estadual Paulista, Departamento de Bioquimica e Tecnologia Quimica, Rua Francisco Degni s/n, Quitandinha, 14800-900 Araraquara, SP (Brazil); Paris, E.C. [Empresa Brasileira de Pesquisa Agropecuaria, Embrapa Instrumentacao, Rua XV de novembro, 1452, Centro, 13.569-970 Sao Carlos, SP (Brazil); Zaghete, M.A.; Longo, E.; Varela, J.A. [Instituto de Quimica, Universidade Estadual Paulista, Departamento de Bioquimica e Tecnologia Quimica, Rua Francisco Degni s/n, Quitandinha, 14800-900 Araraquara, SP (Brazil)

    2012-01-15

    Lead Titanate Zirconate (PZT) perovskite powders were synthesized by microwave hydrothermal method (M-H) at 180 {sup o}C for different time periods (2, 4, 8 and 12 h) with the presence of aqueous polyvinyl alcohol (PVA) solution 0.36 g L{sup -1}. The X-Ray diffraction (XRD), SE-FEG as well as the measurements of photoluminescence (PL) emission were used for monitoring the formation of a perovskite phase with random polycrystalline distortion in the structure. Emission spectra with fixed excitation wavelength of 350 nm showed higher value for the powder obtained after undergoing 8 h of treatment. A theoretical model derived from previous calculations allows us to discuss the origin of photoluminescence emission in the powders, which can be further related to the local disorder in the network of both ZrO{sub 6} and TiO{sub 6} octahedral, and dodecahedral PbO{sub 12}. The new morphology initially observed from the PZT perovskite crystal growth bearing the shape of fine plates is found to be directly related to photoluminescence emission with energy lower than that present in the PZT with cube-like morphology that emits in 560 nm. - Highlights: > This work details the efficiency of microwave hydrothermal synthesis in obtaining PZT powders. > PVA is used as a crystallization agent of PZT particles. > PZT particles presented photoluminescent (PL) behavior. > There aren't previous reports of photoluminescent PZT obtained by microwave hydrothermal synthesis. > Photoluminescence is one more interesting property for technological applications this material.

  19. ELECTRON MICROSCOPIC INVESTIGATION OF YTTRIUM ALUMINUM GARNET POWDERS Y3AL5O12, SYNTHESIZED BY SOL–GEL METHOD

    OpenAIRE

    A. E. Baranchikov; V. A. Maslov; S. V. Shcherbakov; V. A. Usachyov; N. E. Kononenko; P. P. Fedorov; K. V. Dukelskiy

    2015-01-01

    Subject of Study. The paper presents results of characterization for neodymium doped yttrium aluminum garnet nanopowders - YAG:Nd3+ by the method of scanning electronic microscopy. Method. Synthesis of YAG:Nd3+ was carried out by sol-gel method from nitrate or acetate - nitrate solutions with addition of some organic compounds and ammonia as well. Such substances were used as the source ones: oxides of neodymium and yttrium with the content of the basic substance equal to 99.999 %; organic co...

  20. Y2O3-MgO Nano-Composite Synthesized by Plasma Spraying and Thermal Decomposition of Solution Precursors

    Science.gov (United States)

    Muoto, Chigozie Kenechukwu

    and improved the dispersion of the component phases. Two suspension types, made with powders synthesized from the Y[n]Mg[n] and Y[n]Mg[a] precursor mixtures were sprayed by SPS. The densities and hardnesses of the coatings deposited using the two powder types were similar. However, the microstructure of coatings deposited using the Y[n]Mg[a]-synthesized powder exhibited some eutectic configuration which was not observed in the coatings deposited using the Y[n]Mg[n]-synthesized powder.

  1. MODELING MERCURY CONTROL WITH POWDERED ACTIVATED CARBON

    Science.gov (United States)

    The paper presents a mathematical model of total mercury removed from the flue gas at coal-fired plants equipped with powdered activated carbon (PAC) injection for Mercury control. The developed algorithms account for mercury removal by both existing equipment and an added PAC in...

  2. Mechanical alloying of Hf and Fe powders

    International Nuclear Information System (INIS)

    Mendoza Zelis, L.; Crespo, E.; Creus, M.; Damonte, L.C.; Sanchez, F.H.; Punte, G.

    1994-01-01

    Pure crystalline Hf and Fe powders were mixed and milled under an argon atmosphere. The evolution of the system with milling time was followed with Moessbauer effect spectroscopy and X-ray diffraction. The results indicate that in the first stages an amorphous Fe-rich alloy was gradually formed together with a solid solution of Hf in Fe beyond the solubility limit. (orig.)

  3. USING POWDERED ACTIVATED CARBON: A CRITICAL REVIEW

    Science.gov (United States)

    Because the performance of powdered activated carbon (PAC) for uses other than taste and odor control is poorly documented, the purpose of this article is to critically review uses that have been reported (i.e., pesticides and herbicides, synthetic organic chemicals, and trihalom...

  4. Powder Characterization and Optimization for Additive Manufacturing

    NARCIS (Netherlands)

    Cordova, Laura; Campos, Mónica; Tinga, Tiedo

    2017-01-01

    Achieving the optimal quality for Additive Manufactured (AM) parts does not only depend on setting the right process parameters. Material feedstock also plays an important role when aiming for high performance products. The metal AM processes that are most applicable to industry, Powder Bed Fusion

  5. Evaluating the Johanson theory for titanium powder

    CSIR Research Space (South Africa)

    Chikosha, S

    2015-05-01

    Full Text Available Direct powder rolling (DPR)/roll compaction has been labelled a complex and sample sensitive process. As such the design of the instrument and the determination of the optimal processing conditions for a given feed are very challenging...

  6. Dry powder inhalers for pulmonary drug delivery

    NARCIS (Netherlands)

    Frijlink, H.W.; De Boer, A.H.

    2004-01-01

    The pulmonary route is an interesting route for drug administration, both for effective local therapy (asthma, chronic obstructive pulmonary disease or cystic fibrosis) and for the systemic administration of drugs (e.g., peptides and proteins). Well-designed dry powder inhalers are highly efficient

  7. COMPARATIVE EFFICACY OF Acorus calamus POWDER AND ...

    African Journals Online (AJOL)

    The efficacy of the powder of a natural plant product (Acorus calamus L.) and two synthetic insecticides (i.e. Pirimiphos methyl and Rotenone) was compared in the laboratory for the control Sitophilus oryzea (L), Rhizopertha dominica (F) and Tribolium castaneum (Herbst) in stored wheat grains. Seven concentrations of the ...

  8. Sol-Gel Synthesis Of Aluminoborosilicate Powders

    Science.gov (United States)

    Bull, Jeffrey; Leiser, Daniel; Selvaduray, Guna

    1992-01-01

    Application of sol-gel process to synthesis of aluminoborosilicate powders shows potential for control of microstructures of materials. Development of materials having enhanced processing characteristics prove advantageous in extending high-temperature endurance of fibrous refractory composite insulation made from ceramic fibers.

  9. Progress in Titanium Metal Powder Injection Molding

    Directory of Open Access Journals (Sweden)

    Randall M. German

    2013-08-01

    Full Text Available Metal powder injection molding is a shaping technology that has achieved solid scientific underpinnings. It is from this science base that recent progress has occurred in titanium powder injection molding. Much of the progress awaited development of the required particles with specific characteristics of particle size, particle shape, and purity. The production of titanium components by injection molding is stabilized by a good understanding of how each process variable impacts density and impurity level. As summarized here, recent research has isolated the four critical success factors in titanium metal powder injection molding (Ti-MIM that must be simultaneously satisfied—density, purity, alloying, and microstructure. The critical role of density and impurities, and the inability to remove impurities with sintering, compels attention to starting Ti-MIM with high quality alloy powders. This article addresses the four critical success factors to rationalize Ti-MIM processing conditions to the requirements for demanding applications in aerospace and medical fields. Based on extensive research, a baseline process is identified and reported here with attention to linking mechanical properties to the four critical success factors.

  10. Neutron Powder Diffraction and Constrained Refinement

    DEFF Research Database (Denmark)

    Pawley, G. S.; Mackenzie, Gordon A.; Dietrich, O. W.

    1977-01-01

    The first use of a new program, EDINP, is reported. This program allows the constrained refinement of molecules in a crystal structure with neutron diffraction powder data. The structures of p-C6F4Br2 and p-C6F4I2 are determined by packing considerations and then refined with EDINP. Refinement is...

  11. Evaluation of powder metallurgy superalloy disk materials

    Science.gov (United States)

    Evans, D. J.

    1975-01-01

    A program was conducted to develop nickel-base superalloy disk material using prealloyed powder metallurgy techniques. The program included fabrication of test specimens and subscale turbine disks from four different prealloyed powders (NASA-TRW-VIA, AF2-1DA, Mar-M-432 and MERL 80). Based on evaluation of these specimens and disks, two alloys (AF2-1DA and Mar-M-432) were selected for scale-up evaluation. Using fabricating experience gained in the subscale turbine disk effort, test specimens and full scale turbine disks were formed from the selected alloys. These specimens and disks were then subjected to a rigorous test program to evaluate their physical properties and determine their suitability for use in advanced performance turbine engines. A major objective of the program was to develop processes which would yield alloy properties that would be repeatable in producing jet engine disks from the same powder metallurgy alloys. The feasibility of manufacturing full scale gas turbine engine disks by thermomechanical processing of pre-alloyed metal powders was demonstrated. AF2-1DA was shown to possess tensile and creep-rupture properties in excess of those of Astroloy, one of the highest temperature capability disk alloys now in production. It was determined that metallographic evaluation after post-HIP elevated temperature exposure should be used to verify the effectiveness of consolidation of hot isostatically pressed billets.

  12. Laboratory Powder Metallurgy Makes Tough Aluminum Sheet

    Science.gov (United States)

    Royster, D. M.; Thomas, J. R.; Singleton, O. R.

    1993-01-01

    Aluminum alloy sheet exhibits high tensile and Kahn tear strengths. Rapid solidification of aluminum alloys in powder form and subsequent consolidation and fabrication processes used to tailor parts made of these alloys to satisfy such specific aerospace design requirements as high strength and toughness.

  13. Laser Processing Technology using Metal Powders

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Jeong-Hwan; Moon, Young-Hoon [Pusan National University, Busan (Korea, Republic of)

    2012-03-15

    The purpose of this paper is to review the state of laser processing technology using metal powders. In recent years, a series of research and development efforts have been undertaken worldwide to develop laser processing technologies to fabricate metal-based parts. Layered manufacturing by the laser melting process is gaining ground for use in manufacturing rapid prototypes (RP), tools (RT) and functional end products. Selective laser sintering / melting (SLS/SLM) is one of the most rapidly growing rapid prototyping techniques. This is mainly due to the processes's suitability for almost any materials, including polymers, metals, ceramics and many types of composites. The interaction between the laser beam and the powder material used in the laser melting process is one of the dominant phenomena defining feasibility and quality. In the case of SLS, the powder is not fully melted during laser scanning, therefore the SLS-processed parts are not fully dense and have relatively low strength. To overcome this disadvantage, SLM and laser cladding (LC) processes have been used to enable full melting of the powder. Further studies on the laser processing technology will be continued due to the many potential applications that the technology offers.

  14. Quantification of the compactibility of pharmaceutical powders

    DEFF Research Database (Denmark)

    Sonnergaard, Jørn

    2006-01-01

    The purpose of this study is to investigate and to quantify the compactibility of pharmaceutical powders by a simple linear relationship between the diametral compressive strength of tablets and the applied compaction pressure. The mechanical strength of the tablets is characterized as the crushing...

  15. Powder-Metallurgy Process And Product

    Science.gov (United States)

    Paris, Henry G.

    1988-01-01

    Rapid-solidification processing yields alloys with improved properties. Study undertaken to extend favorable property combinations of I/M 2XXX alloys through recently developed technique of rapid-solidification processing using powder metallurgy(P/M). Rapid-solidification processing involves impingement of molten metal stream onto rapidly-spinning chill block or through gas medium using gas atomization technique.

  16. (11) EFFECT OF POWDERED CASTOR BEAN

    African Journals Online (AJOL)

    Adeyinka Odunsi

    A study was carried out at the Toxicology laboratory of the Department of Crop and Environmental protection,. Ladoke Akintola University of Technology Ogbomoso, to determine the effects of powdered castor oil seed. (Ricinus communis L.Euphorbiaceae) on kidney, liver, spleen of albino rats. The rats were in five groups, ...

  17. Influence of calcination temperature on the zirconia microstructure synthesized by complex polymerization method (CPM): a comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Santos, R.L.P.; Mota, F.V.; Nascimento, R.M.; Henriques, B.P.; Silva, F.S.; Assis, R. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

    2016-07-01

    Full text: The aim of this study was to accomplish a previous characterization of the zirconia synthesized by Complex Polymerization Method (CPM) using yttria as stabilizing agent and different calcination temperatures. The powders were crystallized at 800, 900 and 1000 °C for 2h. The structural evolution Y-TZP powders were characterized by X-Ray Diffraction (XRD) and Micro-Raman Spectroscopy. The thermal properties of the calcined pre-pyrolyzed (350 °C for 4 h), samples were investigated by simultaneous thermo analysis (TGA/DTA). After heat treatment the phase Y-TZP was obtained of a single-phase, with absence of the deleterious phases. The results show that average crystallite size of the powder synthesized with 3% of Yttria dopant, increased from 11.5 to 27.9 nm when the calcination temperature increased from 800 to 1000 °C. This behavior was observed for all specimens independent of the Yttria content. The micro-Raman indicate the presence of the tetragonal phase for all samples independent of the calcination temperature employed. (author)

  18. Micro-powder injection moulding of tungsten

    International Nuclear Information System (INIS)

    Zeep, B.

    2007-12-01

    For He-cooled Divertors as integral components of future fusion power plants, about 300000 complex shaped tungsten components are to be fabricated. Tungsten is the favoured material because of its excellent properties (high melting point, high hardness, high sputtering resistance, high thermal conductivity). However, the material's properties cause major problems for large scale production of complex shaped components. Due to the resistance of tungsten to mechanical machining, new fabrication technologies have to be developed. Powder injection moulding as a well established shaping technology for a large scale production of complex or even micro structured parts might be a suitable method to produce tungsten components for fusion applications but is not yet commercially available. The present thesis is dealing with the development of a powder injection moulding process for micro structured tungsten components. To develop a suitable feedstock, the powder particle properties, the binder formulation and the solid load were optimised. To meet the requirements for a replication of micro patterned cavities, a special target was to define the smallest powder particle size applicable for micro-powder injection moulding. To investigate the injection moulding performance of the developed feedstocks, experiments were successfully carried out applying diverse cavities with structural details in micro dimension. For debinding of the green bodies, a combination of solvent debinding and thermal debinding has been adopted for injection moulded tungsten components. To develop a suitable debinding strategy, a variation of the solvent debinding time, the heating rate and the binder formulation was performed. For investigating the thermal consolidation behaviour of tungsten components, sinter experiments were carried out applying tungsten powders suitable for micro-powder injection moulding. First mechanical tests of the sintered samples showed promising material properties such as a

  19. Powder metallurgy of turbine disc alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ingesten, N.G. (Dep. of Engineering Metals)

    1981-03-01

    The first part embraced a study of carbide precipitated in IN 100 and astrology powders. The powder was heat treated at temperatures between 950/sup 0/C and 1150/sup 0/C. After aging at 950-1100/sup 0/C the MC-carbides formed during atomization were replaced by M/sub 23/C/sub 6/-carbides. After 1150/sup 0/C treatments the MC carbides were present again. Precipitation comparable with that obtained in HIP:ed specimens was not observed at free particle surfaces. However, powder particles which had agglomerated during atomization often exhibited considerable precipitation at contiguous surfaces. Obviously, contact between the particles must occur if coarse precipitation at particle surfaces is to develop. Reduced PPB-precipitation was obtained by pre-heat- treatment of powder before compaction. It is suggested that the carbon otherwise available for PPB-precipitation forms carbides in the interior of the powder particles. The aim of the second part was to ..gamma..-strengthen a Co-based super-alloy (Co-15Cr-3Mo-5Ti). Here the Ti-addition gives a coherent and ordered ..gamma..-phase Co/sub 3/Ti. However, upon ageing the alloy is unstable in order to increase the stability modifications of the alloy were prepared by: leaving out the Mo-content, adding 10 % Ni and by decreasing the Ti-content to 4.2 %. In addition, the effect of enhanced grain size and of deformation was investigated. Significant reduction of the transformation rate was only obtained by decresing the Ti-content while deformation of the alloy greatly increased the transformation rate.(author).

  20. Moisture-induced caking of beverage powders.

    Science.gov (United States)

    Chávez Montes, Edgar; Santamaría, Nadia Ardila; Gumy, Jean-Claude; Marchal, Philippe

    2011-11-01

    Beverage powders can exhibit caking during storage due to high temperature and moisture conditions, leading to consumer dissatisfaction. Caking problems can be aggravated by the presence of sensitive ingredients. The caking behaviour of cocoa beverage powders, with varying amounts of a carbohydrate sensitive ingredient, as affected by climate conditions was studied in this work. Sorption isotherms of beverage powders were determined at water activities (a(w) ) ranging from 0.1 to 0.6 in a moisture sorption analyser by gravimetry and fitted to the Brunauer-Emmett-Teller (BET) or the Guggenheim-Anderson-de Boer (GAB) equation. Glass transition temperatures (T(g) ) at several a(w) were analysed by differential scanning calorimetry and fitted to the Gordon-Taylor equation. Deduced T(g) = f(a(w) ) functions helped to identify stability or caking zones. Specific experimental methods, based on the analysis of mechanical properties of powder cakes formed under compression, were used to quantify the degree of caking. Pantry tests complemented this study to put in evidence the visual perception of powder caking with increasing a(w) . The glass transition approach was useful to predict the risks of caking but was limited to products where T(g) can be measured. On the other hand, quantification of the caking degree by analysis of mechanical properties allowed estimation of the extent of degradation for each product. This work demonstrated that increasing amounts of a carbohydrate sensitive ingredient in cocoa beverages negatively affected their storage stability. Copyright © 2011 Society of Chemical Industry.