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Sample records for magnesium aluminum spinel

  1. In vitro biological and tribological properties of transparent magnesium aluminate (Spinel) and aluminum oxynitride (ALON®).

    PubMed

    Bodhak, Subhadip; Balla, Vamsi Krishna; Bose, Susmita; Bandyopadhyay, Amit; Kashalikar, Uday; Jha, Santosh K; Sastri, Suri

    2011-06-01

    The purpose of this first generation investigation is to evaluate the in vitro cytotoxicity, cell-materials interactions and tribological performance of Spinel and ALON® transparent ceramics for potential wear resistant load bearing implant applications. Besides their non-toxicity, the high surface energy of these ceramics significantly enhanced in vitro cell-materials interactions compared to bioinert commercially pure Ti as control. These transparent ceramics with high hardness in the range of 1334 and 1543 HV showed in vitro wear rate of the order of 10⁻⁶ mm³ Nm⁻¹ against Al₂O₃ ball at a normal load of 20 N.

  2. Tensile strain effect in ferroelectric perovskite oxide thin films on spinel magnesium aluminum oxide substrate

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaolan

    Ferroelectrics are used in FeRAM (Ferroelectric random-access memory). Currently (Pb,Zr)TiO3 is the most common ferroelectric material. To get lead-free and high performance ferroelectric material, we investigated perovskite ferroelectric oxides (Ba,Sr)TiO3 and BiFeO3 films with strain. Compressive strain has been investigated intensively, but the effects of tensile strain on the perovskite films have yet to be explored. We have deposited (Ba,Sr)TiO3, BiFeO3 and related films by pulsed laser deposition (PLD) and analyzed the films by X-ray diffractometry (XRD), atomic force microscopy (AFM), etc. To obtain inherently fully strained films, the selection of the appropriate substrates is crucial. MgAl2O4 matches best with good quality and size, yet the spinel structure has an intrinsic incompatibility to that of perovskite. We introduced a rock-salt structure material (Ni 1-xAlxO1+delta) as a buffer layer to mediate the structural mismatch for (Ba,Sr)TiO3 films. With buffer layer Ni1-xAlxO1+delta, we show that the BST films have high quality crystallization and are coherently epitaxial. AFM images show that the films have smoother surfaces when including the buffer layer, indicating an inherent compatibility between BST-NAO and NAO-MAO. In-plane Ferroelectricity measurement shows double hysteresis loops, indicating an antiferroelectric-like behavior: pinned ferroelectric domains with antiparallel alignments of polarization. The Curie temperatures of the coherent fully strained BST films are also measured. It is higher than 900°C, at least 800°C higher than that of bulk. The improved Curie temperature makes the use of BST as FeRAM feasible. We found that the special behaviors of ferroelectricity including hysteresis loop and Curie temperature are due to inherent fully tensile strain. This might be a clue of physics inside ferroelectric stain engineering. An out-of-plane ferroelectricity measurement would provide a full whole story of the tensile strain. However, a

  3. Superplasticity in Thermomechanically Processed High Magnesium Aluminum-Magnesium Alloys.

    DTIC Science & Technology

    1984-03-01

    California DTIC EECTE JL I 1984 THESIS SUPERPLASTICITY IN THERMOMECHANICALLY PROCESSED HIGH MAGNESIUM ALUMINUM-MAGNESIUM ALLOYS C:L by CD) John J. Becker...High Magnesium Aluminum- March 1984 Magnesium Alloys S. PERFORMING ORG. REPORT NUMBER 7. AUTHOR(@) S. CONTRACT OR GRANT NUMBER(&) John J. Becker 9...magnesium, aluminum-magnesium alloys were investigated. The thermomechanical processing itself included warm rolling at 300°C to 94% reduction

  4. Synthesis of magnesium aluminate spinel by periclase and alumina chlorination

    SciTech Connect

    Orosco, Pablo; Barbosa, Lucía; Ruiz, María del Carmen

    2014-11-15

    Highlights: • Use of chlorination for the synthesis of magnesium aluminate spinel. • The reagents used were alumina, periclase and chlorine. • Isothermal and non-isothermal assays were performed in air and Cl{sub 2}–N{sub 2} flows. • The chlorination produced magnesium aluminate spinel at 700 °C. • Selectivity of the chlorination reaction to obtain spinel is very high. - Abstract: A pyrometallurgical route for the synthesis of magnesium aluminate spinel by thermal treatment of a mechanical mixture containing 29 wt% MgO (periclase) and 71 wt% Al{sub 2}O{sub 3} (alumina) in chlorine atmosphere was developed and the results were compared with those obtained by calcining the same mixture of oxides in air atmosphere. Isothermal and non-isothermal assays were performed in an experimental piece of equipment adapted to work in corrosive atmospheres. Both reagents and products were analyzed by differential thermal analysis (DTA), X-ray diffraction (XRD) and X-ray fluorescence (XRF). Thermal treatment in Cl{sub 2} atmosphere of the MgO–Al{sub 2}O{sub 3} mixture produces magnesium aluminate spinel at 700 °C, while in air, magnesium spinel is generated at 930 °C. The synthesis reaction of magnesium aluminate spinel was complete at 800 °C.

  5. Electrodeposition of magnesium and magnesium/aluminum alloys

    DOEpatents

    Mayer, Anton

    1988-01-01

    Electrolytes and plating solutions for use in processes for electroplating and electroforming pure magnesium and alloys of aluminum and magnesium and also electrodeposition processes. An electrolyte of this invention is comprised of an alkali metal fluoride or a quaternary ammonium halide, dimethyl magnesium and/or diethyl magnesium, and triethyl aluminum and/or triisobutyl aluminum. An electrolyte may be dissolved in an aromatic hydrocarbon solvent to form a plating solution. The proportions of the component compounds in the electrolyte are varied to produce essentially pure magnesium or magnesium/aluminum alloys having varying selected compositions.

  6. Electrodeposition of magnesium and magnesium/aluminum alloys

    DOEpatents

    Mayer, A.

    1988-01-21

    Electrolytes and plating solutions for use in processes for electroplating and electroforming pure magnesium and alloys of aluminum and magnesium and also electrodeposition processes. An electrolyte of this invention is comprised of an alkali metal fluoride or a quaternary ammonium halide, dimethyl magnesium and/or diethyl magnesium, and triethyl aluminum and/or triisobutyl aluminum. An electrolyte may be dissolved in an aromatic hydrocarbon solvent to form a plating solution. The proportions of the component compounds in the electrolyte are varied to produce essentially pure magnesium or magnesium/aluminum alloys having varying selected compositions.

  7. Nitrogen-stabilized aluminum oxide spinel /ALON/

    NASA Astrophysics Data System (ADS)

    Corbin, N. D.; McCauley, J. W.

    1982-10-01

    The fabrication techniques, material properties, and performance features of the nitrogen stabilized aluminum oxide spinel ceramic ALON for structural and optical applications are detailed. ALON has been sintered into a single phase form to produce an isotropic, dense, transparent material. Specimens produced have a Knoop hardness of 1800, an elastic modulus of 46 million psi, a room temperature fracture strength of 45,000 psi, and experience negligible oxidation in air up to 1200 C. The dielectric constant and loss tangent at 10 MHz are 8.56 and 0.0004, respectively, and an IR cutoff has been set at 5.2 microns. The ALON thermal expansion coefficient is 7/1,000,000 per deg C from 25-1000 C. Applications requiring alpha-Al2O3 are foreseen for ALON.

  8. Neutron irradiation influence on magnesium aluminium spinel inversion

    NASA Astrophysics Data System (ADS)

    Skvortsova, V.; Mironova-Ulmane, N.; Ulmanis, U.

    2002-05-01

    Grown by the Verneuil method MgO · nAl 2O 3 single crystals and natural spinel crystal have been studied using X-ray diffraction and photoluminescence spectra. The fast neutron irradiation of magnesium aluminium spinel leads to the lattice parameter decrease. The bond lengths of Mg-O and Al-O vary with the u-parameter and the lattice parameter. On the other hand, the bond lengths are related with the inversion parameter. Using changes of the lattice parameter during irradiation we have calculated the inversion parameter, which is 15-20%. In the luminescence spectra, the fast neutron radiation (fluence 10 16 cm -2) produces an increase in the intensity ratio of the N- to R-lines by 5-20%. Taking into account that intensity of the N-lines is closely associated with the inversion parameter, it is possible to state that the neutron irradiation causes the increasing of the spinel inversion.

  9. Formation of a Spinel Coating on AZ31 Magnesium Alloy by Plasma Electrolytic Oxidation

    NASA Astrophysics Data System (ADS)

    Sieber, Maximilian; Simchen, Frank; Scharf, Ingolf; Lampke, Thomas

    2016-03-01

    Plasma electrolytic oxidation (PEO) is a common means for the surface modification of light metals. However, PEO of magnesium substrates in dilute electrolytes generally leads to the formation of coatings consisting of unfavorable MgO magnesium oxide. By incorporation of electrolyte components, the phase constitution of the oxide coatings can be modified. Coatings consisting exclusively of MgAl2O4 magnesium-aluminum spinel are produced by PEO in an electrolyte containing hydroxide, aluminate, and phosphate anions. The hardness of the coatings is 3.5 GPa on Martens scale on average. Compared to the bare substrate, the coatings reduce the corrosion current density in dilute sodium chloride solution by approx. one order of magnitude and slightly shift the corrosion potential toward more noble values.

  10. Hard transparent domes and windows from magnesium aluminate spinel

    NASA Astrophysics Data System (ADS)

    DiGiovanni, Anthony A.; Fehrenbacher, Larry; Roy, Don W.

    2005-05-01

    Transparent magnesium aluminate spinel is an attractive material for use in a wide range of optical applications including windows, domes, armor, and lenses, which require excellent transmission from the visible through to the mid IR. Theoretical transmission is very uniform and approaches 87% between 0.3 to 5 microns. Transmission characteristics rival that of ALON and sapphire in the mid-wave IR, making it especially attractive for the everincreasing performance requirements of current and next-generation IR imaging systems. Future designs in missile technology will require materials that can meet stringent performance demands in both optical and RF wavelengths. Loss characteristics for spinel are being investigated to meet those demands. Technology Assessment and Transfer Inc. (TA&T), have established a 9000 ft2 production facility for optical quality spinel based on the traditional hot-pressing followed by hot isostatic pressing (HIPing) route. Additionally, TA&T is developing pressureless sintering - a highly scalable, near net shape processing method based on traditional ceramic processing technology - to fabricate optical components. These two main processing approaches allow the widest variety of applications to be addressed using a range of optical components and configurations. The polycrystalline nature of spinel facilitates near net shape processing, which provides the potential to fabricate physically larger optical parts or larger quantities of parts at significantly lower costs compared to single crystal materials such as sapphire. Current research is focused at optimizing the processing parameters for both synthesis routes to maximize strength and transparency while minimizing the cost of fabrication.

  11. Production of Magnesium by Vacuum Aluminothermic Reduction with Magnesium Aluminate Spinel as a By-Product

    NASA Astrophysics Data System (ADS)

    Wang, Yaowu; You, Jing; Peng, Jianping; Di, Yuezhong

    2016-06-01

    The Pidgeon process currently accounts for 85% of the world's magnesium production. Although the Pidgeon process has been greatly improved over the past 10 years, such production still consumes much energy and material and creates much pollution. The present study investigates the process of producing magnesium by employing vacuum aluminothermic reduction and by using magnesite as material and obtaining magnesium aluminate spinel as a by-product. The results show that compared with the Pidgeon process, producing magnesium by vacuum aluminothermic reduction can save materials by as much as 50%, increase productivity up to 100%, and save energy by more than 50%. It can also reduce CO2 emission by up to 60% and realize zero discharge of waste residue. Vacuum aluminothermic reduction is a highly efficient, low-energy-consumption, and environmentally friendly method of producing magnesium.

  12. Lithium-aluminum-magnesium electrode composition

    DOEpatents

    Melendres, Carlos A.; Siegel, Stanley

    1978-01-01

    A negative electrode composition is presented for use in a secondary, high-temperature electrochemical cell. The cell also includes a molten salt electrolyte of alkali metal halides or alkaline earth metal halides and a positive electrode including a chalcogen or a metal chalcogenide as the active electrode material. The negative electrode composition includes up to 50 atom percent lithium as the active electrode constituent and a magnesium-aluminum alloy as a structural matrix. Various binary and ternary intermetallic phases of lithium, magnesium, and aluminum are formed but the electrode composition in both its charged and discharged state remains substantially free of the alpha lithium-aluminum phase and exhibits good structural integrity.

  13. Mechanical Properties of Several Magnesium and Aluminum Composites

    DTIC Science & Technology

    1992-12-01

    34AD-A262 481 ARMY RESEARCH LABORATORY Mechanical Properties of Several Magnesium and Aluminum Composites Nikos Tsangarakis and Barmac Taleghani ARL...ESJEI L .PwmOM N.ajmns Mechanical Properties of Several Magnesium and Aluminum Composites 2.AUIwORU Nikos Tsangarakis and Barmac Taleghani 7. PERONUMMN...Several composites of magnesiumn and aluminum alloys were tested In order to assess and evaluate their mechanical properties . The magnesium alloys were

  14. Transparent magnesium aluminate spinel: a prospective biomaterial for esthetic orthodontic brackets.

    PubMed

    Krishnan, Manu; Tiwari, Brijesh; Seema, Saraswathy; Kalra, Namitha; Biswas, Papiya; Rajeswari, Kotikalapudi; Suresh, Madireddy Buchi; Johnson, Roy; Gokhale, Nitin M; Iyer, Satish R; Londhe, Sanjay; Arora, Vimal; Tripathi, Rajendra P

    2014-11-01

    Adult orthodontics is recently gaining popularity due to its importance in esthetics, oral and general health. However, none of the currently available alumina or zirconia based ceramic orthodontic brackets meet the esthetic demands of adult patients. Inherent hexagonal lattice structure and associated birefringence limits the visible light transmission in polycrystalline alumina and make them appear white and non transparent. Hence focus of the present study was to assess the feasibility of using magnesium aluminate (MgAl2O4) spinel; a member of the transparent ceramic family for esthetic orthodontic brackets. Transparent spinel specimens were developed from commercially available white spinel powder through colloidal shaping followed by pressureless sintering and hot isostatic pressing at optimum conditions of temperature and pressure. Samples were characterized for chemical composition, phases, density, hardness, flexural strength, fracture toughness and optical transmission. Biocompatibility was evaluated with in-vitro cell line experiments for cytotoxicity, apoptosis and genotoxicity. Results showed that transparent spinel samples had requisite physico-chemical, mechanical, optical and excellent biocompatibility for fabricating orthodontic brackets. Transparent spinel developed through this method demonstrated its possibility as a prospective biomaterial for developing esthetic orthodontic brackets.

  15. Magnesium, aluminum and lead in various brain areas

    SciTech Connect

    Zumkley, H.; Bertram, H.P.; Brandt, M.; Roedig, M.; Spieker, C.

    1986-01-01

    Whereas the lead concentrations were increased in brain tissue of patients with chronic alcoholism, the aluminum concentrations remained within the normal range. The magnesium concentrations were found decreased in patients with chronic alcoholism compared to normal controls. The sources for the elevated lead levels seem to be the increased intake of alcohol. The decreased magnesium levels are probably caused by an increased loss of magnesium with the urine, malnutrition, malabsorption, hormonal factors and drugs. Various neurological disorders which often accompanied chronic alcoholism may be caused or aggravated by lead encephalopathy and hypomagnesemia. Therapeutical implications may be the early substitution of magnesium deficiency in chronic alcoholism. 10 references, 5 figures.

  16. The viability of aluminum Zintl anion moieties within magnesium-aluminum clusters

    SciTech Connect

    Wang, Haopeng; Jae Ko, Yeon; Zhang, Xinxing; Gantefoer, Gerd; Bowen, Kit H. E-mail: akandalam@wcupa.edu; Schnoeckel, Hansgeorg; Eichhorn, Bryan W.; Jena, Puru; Kiran, Boggavarapu E-mail: akandalam@wcupa.edu; Kandalam, Anil K. E-mail: akandalam@wcupa.edu

    2014-03-28

    Through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations, we have investigated the extent to which the aluminum moieties within selected magnesium-aluminum clusters are Zintl anions. Magnesium-aluminum cluster anions were generated in a pulsed arc discharge source. After mass selection, photoelectron spectra of Mg{sub m}Al{sub n}{sup −} (m, n = 1,6; 2,5; 2,12; and 3,11) were measured by a magnetic bottle, electron energy analyzer. Calculations on these four stoichiometries provided geometric structures and full charge analyses for the cluster anions and their neutral cluster counterparts, as well as photodetachment transition energies (stick spectra). Calculations revealed that, unlike the cases of recently reported sodium-aluminum clusters, the formation of aluminum Zintl anion moieties within magnesium-aluminum clusters was limited in most cases by weak charge transfer between the magnesium atoms and their aluminum cluster moieties. Only in cases of high magnesium content, e.g., in Mg{sub 3}Al{sub 11} and Mg{sub 2}Al{sub 12}{sup −}, did the aluminum moieties exhibit Zintl anion-like characteristics.

  17. Superplastic flow in a non-stoichiometric ceramic: Magnesium aluminate spinel

    SciTech Connect

    Lappalainen, R.; Pannikkat, A.; Raj, R. . Dept. of Materials Science and Engineering)

    1993-04-01

    Tensile superplastic deformation of ceramics is often limited by their susceptibility to intergranular cavitation. However, the authors find that fine grained magnesium aluminate spinel exhibits unusual superplastic ductility at strain rates of up to 5 [times] 10[sup [minus]4]s[sup [minus]1] and at temperatures below 1,280 C. The ductility is all the more remarkable because the flow stress of the spinel was in the range of several hundred MPa. The authors propose that the unusual cavitation resistance of interfaces in spinel is related to its non-stoichiometry. They further propose that the non-linear threshold stress like rheology which they have measured is related to an electrical double (barrier) layer which is postulated to form to compensate the net charge at interfaces of non-stoichiometric ceramics. They estimate that a boundary double layer potential, [psi][sub b], of 5-50 mV can account for this threshold stress. The phenomenological characteristics of superplastic flow in the spinel are shared by other non-stoichiometric ceramics such as yttria stabilized zirconia, hydroxyapatite and zinc sulfide.

  18. Mechanical properties of several magnesium and aluminum composites. Final report

    SciTech Connect

    Tsangarakis, N.; Taleghani, B.

    1992-12-01

    Several composites of magnesium and aluminum alloys were tested in order to assess and evaluate their mechanical properties. The magnesium alloys were AZ91 C, ZE41 A, and commercially pure magnesium, reinforced with 40% by volume continuous graphite fiber. The tensile properties of these composites were not superior to those of unreinforced magnesium and estimates of their fracture toughness were low. The matrices of the aluminum composites were 2124-T6, 6061-T4, 2124-T4, and 2219-T4. The reinforcements were either particulate or whiskers of silicon carbide or boron carbide and their volume content was 15% to 30%. The aluminum composites which were reinforced with silicon carbide particulate exhibited improved yield and ultimate tensile stresses, as well as tensile elastic modulus over the unreinforced aluminum alloys. The 2124-T4/B4C/25p composite exhibited the highest ultimate tensile strength which was 511 MPa. The composite which was reinforced with whiskers of silicon carbide exhibited an endurance limit which was 20% higher than that of the matrix alloy. The compressive properties and fracture toughness of some of these aluminum composites were not improved over those of the unreinforced matrix alloy.... Composites, Mechanical properties.

  19. The Effect of Alloy Additions on Superplasticity in Thermomechanically Processed High Magnesium Aluminum-Magnesium Alloys.

    DTIC Science & Technology

    1984-12-01

    AD-Ri55 142 THE EFFECT OF ALLOY ADDITIONS ON SUPERPLASTICITY IN I/2 THERMOMECHANICALLY PR-.(U) NAVAL POSTGRADUATE SCHOOL UNCLSSIIED MONTEREY CA R J...Ln Monterey, California DTr J U N 1985 * THESIS THE EFFECT OF ALLOY ADDITIONS ON SUPERPLASTICITY IN THERMOMECHANICALLY PROCESSED HIGH MAGNESIUM *0...ALUMINUM-MAGNESIUM ALLOYS >by 0 (Richard J. Self December 1984 C-31 Thesis Advisor: Terry McNelley Approved for public release; distribution is unlimited

  20. Processing method and process modeling of large aperture transparent magnesium aluminate spinel domes

    NASA Astrophysics Data System (ADS)

    Yu, Jian; McWilliams, Brandon; Kilczewski, Steven; Gilde, Gary; Lidie, Ashley; Sands, James

    2009-05-01

    Polycrystalline spinel serves as an alternative to materials such as sapphire and magnesium fluoride that are currently being used in electromagnetic window applications such as missile domes, where high strength, high hardness and high transmittance in the visible and infrared spectra are required. The cubic crystal lattice of spinel imparts an isotropy to the bulk optical property, which eliminates optical distortion due to birefringence that occurs in sapphire and other non-cubic materials. The current study is to find a reliable manufacturing process to produce large magnesium aluminate spinel domes from powder consolidation efficiently. A binder-less dry ball milling process was used to deflocculate the spinel powder to increase its fluidity in an effort to ease the shape-forming. Dry ball milling time trials were conducted at several intervals to determine the appropriate level of time required to break up both the hard and soft agglomerates associated with the virgin spinel powder. The common problems encountered in dry powder shape-forming are crack growth and delamination of the green body during cold isostatic pressing (CIPing). The cracking and the delamination are due to the buildup of stress gradients on the green body that are created by the frictional force between the powder and the die wall or mold wall. To understand the stresses during the CIPing process, a finite element analysis of stresses on the green body was conducted. The simulation was used to evaluate the effect of die tooling and process characteristics on the development of stress gradients in the green body dome. Additionally, the effect of friction between the die wall and powder was examined by the simulation. It was found that by mitigating the frictional forces, cracking and delamination on the green body could be eliminated. A stepped-pressure CIPing technique was developed to reduce stress gradient build-up during CIPing. Also, oleic acid lubricant was applied to the die wall to

  1. Magnesium Recycling of Partially Oxidized, Mixed Magnesium-Aluminum Scrap through Combined Refining and Solid Oxide Membrane Electrolysis Processes

    SciTech Connect

    Xiaofei Guan; Peter A. Zink; Uday B. Pal; Adam C. Powell

    2012-01-01

    Pure magnesium (Mg) is recycled from 19g of partially oxidized 50.5wt.% Mg-Aluminum (Al) alloy. During the refining process, potentiodynamic scans (PDS) were performed to determine the electrorefining potential for magnesium. The PDS show that the electrorefining potential increases over time as the magnesium content inside the Mg-Al scrap decreases. Up to 100% percent of magnesium is refined from the Mg-Al scrap by a novel refining process of dissolving magnesium and its oxide into a flux followed by vapor phase removal of dissolved magnesium and subsequently condensing the magnesium vapor. The solid oxide membrane (SOM) electrolysis process is employed in the refining system to enable additional recycling of magnesium from magnesium oxide (MgO) in the partially oxidized Mg-Al scrap. The combination of the refining and SOM processes yields 7.4g of pure magnesium.

  2. Magnesium Recycling of Partially Oxidized, Mixed Magnesium-Aluminum Scrap Through Combined Refining and Solid Oxide Membrane (SOM) Electrolysis Processes

    SciTech Connect

    Guan, Xiaofei; Zink, Peter; Pal, Uday

    2012-03-11

    Pure magnesium (Mg) is recycled from 19g of partially oxidized 50.5wt.%Mg-Aluminum (Al) alloy. During the refining process, potentiodynamic scans (PDS) were performed to determine the electrorefining potential for magnesium. The PDS show that the electrorefining potential increases over time as the Mg content inside the Mg-Al scrap decreases. Up to 100% percent of magnesium is refined from the Mg-Al scrap by a novel refining process of dissolving magnesium and its oxide into a flux followed by vapor phase removal of dissolved magnesium and subsequently condensing the magnesium vapors in a separate condenser. The solid oxide membrane (SOM) electrolysis process is employed in the refining system to enable additional recycling of magnesium from magnesium oxide (MgO) in the partially oxidized Mg-Al scrap. The combination of the refining and SOM processes yields 7.4g of pure magnesium; could not collect and weigh all of the magnesium recovered.

  3. An investigation of aluminum titanate-spinel composites behavior in radiation

    SciTech Connect

    Cevikbas, G.; Tugrul, A. B.; Boyraz, T.; Buyuk, B.; Onen, U.

    2015-03-30

    In the present work, the radiation attenuation properties of Aluminum titanate (Al{sub 2}TiO{sub 5})-Spinel (MgAl{sub 2}O{sub 4}) ceramics composites were investigated. Al{sub 2}TiO{sub 5}-MgAl{sub 2}O{sub 4} ceramics composites which have different Al{sub 2}TiO{sub 5} percentages (0%, 5% and 10%) were produced and performed against gamma sources. Cs-137 and Co-60 were used as gamma radiation sources. Transmission technique was used in the experiments. The linear and mass attenuation coefficients of the samples were carried out for gamma radiation sources. The experimental results were compared with the theoretical mass attenuation coefficients which were calculated by using XCOM computer code. Increasing Al{sub 2}TiO{sub 5} percentage in the Aluminum titanate/ Spinel ceramics composites causes the higher linear and mass attenuation coefficients of the composites against Cs-137 and Co-60 gamma radioisotopes. Therefore Also theoretical mass attenuation coefficients are compatible with the experimental results. In conclusion, increasing the Aluminum titanate ratio in the Al{sub 2}TiO{sub 5}-MgAl{sub 2}O{sub 4} ceramics composites increases the gamma shielding property of the Al{sub 2}TiO{sub 5}-MgAl{sub 2}O{sub 4} ceramics for nuclear shielding applications.

  4. Color-Center Production and Formation in Electron-Irradiated Magnesium Aluminate Spinel and Ceria

    DOE PAGES

    Costantini, Jean-Marc; Lelong, Gerald; Guillaumet, Maxime; ...

    2016-06-20

    Single crystals of magnesium aluminate spinel (MgAl2O4) with (100) or (110) orientations and cerium dioxide or ceria (CeO2) were irradiated by 1.0-MeV and 2.5-MeV electrons in a high fluence range. Point-defect production was studied by off-line UV-visible optical spectroscopy after irradiation. For spinel, regardless of both crystal orientation and electron energy, two characteristic broad bands centered at photon energies of 5.4 eV and 4.9 eV were assigned to F and F+ centers (neutral and singly-ionized oxygen vacancies), respectively, on the basis of available literature data. No clear differences in colour-centre formation were observed for the two crystal orientations. Using calculationsmore » of displacement cross sections by elastic collisions, these results are consistent with a very large threshold displacement energy (200 eV) for oxygen atoms at RT. A third very broad band centered at 3.7 eV might be attributed either to an oxygen hole center (V-type center) or an F2 dimer center (oxygen di-vacancy). The onset of recovery of these color centers took place at 200°C with almost full bleaching at 600°C. Activation energies (~0.3-0.4 eV) for defect recovery were deduced from the isochronal annealing data by using a first-order kinetics analysis. For ceria, a sub band-gap absorption feature peaked at ~3.1 eV was recorded for 2.5-MeV electron irradiation only. Assuming a ballistic process, we suggest that the latter defect might result from cerium atom displacement on the basis of computed cross sections.« less

  5. Color-Center Production and Formation in Electron-Irradiated Magnesium Aluminate Spinel and Ceria

    SciTech Connect

    Costantini, Jean-Marc; Lelong, Gerald; Guillaumet, Maxime; Weber, William J.; Takaki, Seiya; Yasuda, Kazuhiro

    2016-06-20

    Single crystals of magnesium aluminate spinel (MgAl2O4) with (100) or (110) orientations and cerium dioxide or ceria (CeO2) were irradiated by 1.0-MeV and 2.5-MeV electrons in a high fluence range. Point-defect production was studied by off-line UV-visible optical spectroscopy after irradiation. For spinel, regardless of both crystal orientation and electron energy, two characteristic broad bands centered at photon energies of 5.4 eV and 4.9 eV were assigned to F and F+ centers (neutral and singly-ionized oxygen vacancies), respectively, on the basis of available literature data. No clear differences in colour-centre formation were observed for the two crystal orientations. Using calculations of displacement cross sections by elastic collisions, these results are consistent with a very large threshold displacement energy (200 eV) for oxygen atoms at RT. A third very broad band centered at 3.7 eV might be attributed either to an oxygen hole center (V-type center) or an F2 dimer center (oxygen di-vacancy). The onset of recovery of these color centers took place at 200°C with almost full bleaching at 600°C. Activation energies (~0.3-0.4 eV) for defect recovery were deduced from the isochronal annealing data by using a first-order kinetics analysis. For ceria, a sub band-gap absorption feature peaked at ~3.1 eV was recorded for 2.5-MeV electron irradiation only. Assuming a ballistic process, we suggest that the latter defect might result from cerium atom displacement on the basis of computed cross sections.

  6. Color-center production and recovery in electron-irradiated magnesium aluminate spinel and ceria

    NASA Astrophysics Data System (ADS)

    Costantini, Jean-Marc; Lelong, Gérald; Guillaumet, Maxime; Weber, William J.; Takaki, Seiya; Yasuda, Kazuhiro

    2016-08-01

    Single crystals of magnesium aluminate spinel (MgAl2O4) with (1 0 0) or (1 1 0) orientations and cerium dioxide or ceria (CeO2) were irradiated by 1.0 MeV and 2.5 MeV electrons in a high-fluence range. Point-defect production was studied by off-line UV-visible optical spectroscopy after irradiation. For spinel, regardless of both crystal orientation and electron energy, two characteristic broad bands centered at photon energies of 5.4 eV and 4.9 eV were assigned to F and F+ centers (neutral and singly ionized oxygen vacancies), respectively, on the basis of available literature data. No clear differences in color-center formation were observed for the two crystal orientations. Using calculations from displacement cross sections by elastic collisions, these results are consistent with a very large threshold displacement energy (200 eV) for oxygen atoms at room temperature. A third very broad band centered at 3.7 eV might be attributed either to an oxygen hole center (V-type center) or an F2 dimer center (oxygen di-vacancy). The onset of recovery of these color centers took place at 200 °C with almost full bleaching at 600 °C. Activation energies (~0.3-0.4 eV) for defect recovery were deduced from the isochronal annealing data by using a first-order kinetics analysis. For ceria, a sub-band-gap absorption feature, which peaked at ~3.1 eV, was recorded for 2.5 MeV electron irradiation only. Assuming a ballistic process, we suggest that the latter defect might result from cerium atom displacement on the basis of computed cross sections.

  7. The Corrosion of Magnesium and of the Magnesium Aluminum Alloys Containing Manganese

    NASA Technical Reports Server (NTRS)

    Boyer, J A

    1927-01-01

    The extensive use of magnesium and its alloys in aircraft has been seriously handicapped by the uncertainties surrounding their resistance to corrosion. This problem has been given intense study by the American Magnesium Corporation and at the request of the Subcommittee on Materials for Aircraft of the National Advisory Committee for Aeronautics this report was prepared on the corrosion of magnesium. The tentative conclusions drawn from the experimental facts of this investigation are as follows: the overvoltage of pure magnesium is quite high. On immersion in salt water the metal corrodes with the liberation of hydrogen until the film of corrosion product lowers the potential to a critical value. When the potential reaches this value it no longer exceeds the theoretical hydrogen potential plus the overvoltage of the metal. Rapid corrosion consequently ceases. When aluminum is added, especially when in large amounts, the overvoltage is decreased and hydrogen plates out at a much lower potential than with pure magnesium. The addition of small amount of manganese raises the overvoltage back to practically that of pure metal, and the film is again negative.

  8. The temperature of the Icelandic mantle from olivine-spinel aluminum exchange thermometry

    NASA Astrophysics Data System (ADS)

    Matthews, S.; Shorttle, O.; Maclennan, J.

    2016-11-01

    New crystallization temperatures for four eruptions from the Northern Volcanic Zone of Iceland are determined using olivine-spinel aluminum exchange thermometry. Differences in the olivine crystallization temperatures between these eruptions are consistent with variable extents of cooling during fractional crystallization. However, the crystallization temperatures for Iceland are systematically offset to higher temperatures than equivalent olivine-spinel aluminum exchange crystallization temperatures published for MORB, an effect that cannot be explained by fractional crystallization. The highest observed crystallization temperature in Iceland is 1399 ± 20°C. In order to convert crystallization temperatures to mantle potential temperature, we developed a model of multilithology mantle melting that tracks the thermal evolution of the mantle during isentropic decompression melting. With this model, we explore the controls on the temperature at which primary melts begin to crystallize, as a function of source composition and the depth from which the magmas are derived. Large differences (200°C) in crystallization temperature can be generated by variations in mantle lithology, a magma's inferred depth of origin, and its thermal history. Combining this model with independent constraints on the magma volume flux and the effect of lithological heterogeneity on melt production, restricted regions of potential temperature-lithology space can be identified as consistent with the observed crystallization temperatures. Mantle potential temperature is constrained to be 1480-30+37 °C for Iceland and 1318-32+44 °C for MORB.

  9. Final report on the safety assessment of aluminum silicate, calcium silicate, magnesium aluminum silicate, magnesium silicate, magnesium trisilicate, sodium magnesium silicate, zirconium silicate, attapulgite, bentonite, Fuller's earth, hectorite, kaolin, lithium magnesium silicate, lithium magnesium sodium silicate, montmorillonite, pyrophyllite, and zeolite.

    PubMed

    Elmore, Amy R

    2003-01-01

    This report reviews the safety of Aluminum, Calcium, Lithium Magnesium, Lithium Magnesium Sodium, Magnesium Aluminum, Magnesium, Sodium Magnesium, and Zirconium Silicates, Magnesium Trisilicate, Attapulgite, Bentonite, Fuller's Earth, Hectorite, Kaolin, Montmorillonite, Pyrophyllite, and Zeolite as used in cosmetic formulations. The common aspect of all these claylike ingredients is that they contain silicon, oxygen, and one or more metals. Many silicates occur naturally and are mined; yet others are produced synthetically. Typical cosmetic uses of silicates include abrasive, opacifying agent, viscosity-increasing agent, anticaking agent, emulsion stabilizer, binder, and suspending agent. Clay silicates (silicates containing water in their structure) primarily function as adsorbents, opacifiers, and viscosity-increasing agents. Pyrophyllite is also used as a colorant. The International Agency for Research on Cancer has ruled Attapulgite fibers >5 microm as possibly carcinogenic to humans, but fibers <5 microm were not classified as to their carcinogenicity to humans. Likewise, Clinoptilolite, Phillipsite, Mordenite, Nonfibrous Japanese Zeolite, and synthetic Zeolites were not classified as to their carcinogenicity to humans. These ingredients are not significantly toxic in oral acute or short-term oral or parenteral toxicity studies in animals. Inhalation toxicity, however, is readily demonstrated in animals. Particle size, fibrogenicity, concentration, and mineral composition had the greatest effect on toxicity. Larger particle size and longer and wider fibers cause more adverse effects. Magnesium Aluminum Silicate was a weak primary skin irritant in rabbits and had no cumulative skin irritation in guinea pigs. No gross effects were reported in any of these studies. Sodium Magnesium Silicate had no primary skin irritation in rabbits and had no cumulative skin irritation in guinea pigs. Hectorite was nonirritating to the skin of rabbits in a Draize primary skin

  10. An Aluminum Magnesium Hydroxide Stearate-based Skin Barrier Protection Cream Used for the Management of Eczematous Dermatitis

    PubMed Central

    Bhambri, Sanjay; Michaels, Brent

    2008-01-01

    Eczematous dermatoses can often be very difficult to treat. An aluminum magnesium hydroxide stearate-based cream has recently become available for clinical use. Aluminum magnesium hydroxide stearate-based cream provides an alternative option in treating these dermatoses while providing barrier protection against external allergens and irritants. This article reviews various studies evaluating aluminum magnesium hydroxide stearate-based cream. PMID:21212843

  11. Optical And Mechanical Properties Of Highly Transparent Spinel And ALON Domes

    NASA Astrophysics Data System (ADS)

    Hartnett, T. M.; Gentilman, R. L.

    1984-12-01

    Optical and mechanical properties of aluminum oxynitride (ALON) and magnesium aluminate spinel (MgA1204) are presented as well as some optical properties of spinel and ALON hemispherical domes. These materials are transparent in the visible and mid IR and are durable polycrystalline ceramics.

  12. The role of impurities, LIF, and processing on the sintering, microstructure, and optical properties of transparent polycrystalline magnesium aluminate (MgAl2O4) spinel

    NASA Astrophysics Data System (ADS)

    Rubat du Merac, Marc

    Transparent polycrystalline magnesium aluminate (MgAl2O4) spinel has an exceptional combination of properties that is well-suited to fulfill demanding optical applications that few other materials can satisfy. However, spinel is inherently difficult to densify due to high defect formation energies, variable stoichiometry, and extreme sensitivity to powder and processing parameters. In addition, the LiF sintering additive typically required to impart transparency degrades optical and mechanical properties, precluding wider application. Furthermore, there remains a fundamental lack of understanding of the processing-structure-property relationships required to obtain high transparency and good mechanical properties. In this work, hot-press experiments were designed to determine the role of impurities and LiF and the key variables required to obtain transparent spinel. Hot-pressed compacts were characterized with electron microscopy, chemical spectroscopy, and spectrophotometry, and impurities present in parts-per-million in starting powders were found to cause restricted grain size and opacity. LiF addition was found to reduce the content of some impurities by one order of magnitude, counteract absorption, and impart transparency, but also to cause grain coarsening, grain-boundary embrittlement, and scatter. Thermal analysis and residual gas analysis of prepared powders in combination with thermodynamic modeling demonstrated for the first time the specific mechanism by which LiF acts as a cleanser. LiF reacts with impurities to form volatile fluorides, and the temperature at which pressure is applied during hot-pressing determines the extent to which compact-scale differential sintering either traps LiF and volatile fluorides or allows their removal, the latter enabling transparency. The main cause of absorption in hot-pressed spinel compacts was found to be carbon contamination from graphitic hot-press components and it could be completely eliminated with proper

  13. Minimum quantity lubrication machining of aluminum and magnesium alloys

    NASA Astrophysics Data System (ADS)

    Bhowmick, Sukanta

    2011-12-01

    The use of minimum quantity lubrication (MQL) machining, i.e. drilling and tapping of aluminum and magnesium alloys using very low quantities of cutting fluids was studied and the MQL machining performance was compared to dry and conventional flooded conditions. An experimental drilling station with an MQL system was built to measure torque and thrust force responses. Uncoated and diamond-like carbon (DLC) coated HSS drills were tested against 319 Al and AZ91 alloys using 10--50 ml/h of distilled water (H 2O-MQL) and a fatty acid based MQL agent (FA-MQL). The results indicated that H2O-MQL used in conjunction with non-hydrogenated DLC (NH-DLC) coatings reduced the average torque and thrust-force compared to dry cutting and achieved a performance comparable with conventional flooded drilling. At least 103 holes could be drilled using NH-DLC in H2O-MQL and uncoated HSS in FA-MQL in drilling of both 319 Al and AZ91. MQL drilling and tapping provided a stable machining performance, which was evident from the uniform torque and force patterns and also resulted in desirable hole surface, thread quality and chip segments. The maximum temperature generated in the workpiece during MQL machining was lower than that observed in dry drilling and tapping, and comparable to flooded conditions. The mechanical properties of the material adjacent to drilled holes, as evaluated through plastic strain and hardness measurements, revealed a notable softening in case of dry drilling, with magnesium alloys exhibiting a recrystallized grain zone, but not for MQL drilling. Softened aluminum and magnesium promoted adhesion to the tools resulted built-up edge formation and consequently high torques and thrust-forces were generated. NH-DLC coatings' low COF in H 2O-MQL against 319 Al (0.10) and AZ91 (0.12) compared to uncoated HSS (0.63 and 0.65) limited the temperature increase during NH-DLC in H2 O-MQL drilling and hence both torques and thrust forces were effectively reduced.

  14. Textures, microstructures, anisotropy and formability of aluminum-manganese-magnesium and aluminum-magnesium alloys

    NASA Astrophysics Data System (ADS)

    Liu, Jiantao

    In this dissertation work, the microstructure and texture evolution of continuous cast (CC) and direct chill (DC) cast Al-Mn-Mg (AA 3105 and AA 3015) and Al-Mg (AA 5052) alloys during cold rolling and annealing are systematically investigated. Macrotexture analyses were based on three-dimensional orientation distribution functions (ODFs) calculated from incomplete pole figures from X-ray diffraction by using arbitrarily defined cell (ADC) and series expansion methods. A new technique, electron backscatter diffraction (EBSD), was adopted for microtexture and mesotexture investigation. The anisotropy and formability of Al-Mn-Mg and Al-Mg alloys are correlated to the texture results. For aluminum alloys studied in this work, a stronger Cube orientation is observed in DC hot band than in CC hot band after complete recrystallization. alpha and beta fibers become well developed beyond 50% cold rolling in both CC and DC aluminum alloys. The highest intensity along the beta fiber (skeleton line) is located between the Copper and the S orientations in both materials after high cold rolling reductions. In both CC and DC aluminum alloys, a cell structure develops with the indication of increasing CSL Sigma1 boundaries during the early stages of cold rolling. There is no evidence of the development of twin boundaries (Sigma3, Sigma9, Sigma27a & 27b) in either CC or DC aluminum alloys when the cold rolling reductions are less than 40%. The R and Cube textures are dominant recrystallization texture components in CC and DC AA 5052 alloys. The volume fraction of the Cube component is increased by increasing cold rolling reduction and annealing temperature but not by increasing annealing time while the volume fraction of the R component is only increased by increasing cold rolling reduction. Stronger Cube and R orientations are found at the surface layer than at half-thickness layer of cold rolled hot bands after annealing. The Cube and P textures are dominant recrystallization

  15. Evaluation of magnesium-aluminum eutectic to improve combustion efficiency in low burning rate propellants

    NASA Technical Reports Server (NTRS)

    Northam, B. G.; Sullivan, E. M.

    1973-01-01

    A previous investigation indicated that combustion efficiency of low burning-rate propellants could be improved if the aluminum fuel was replaced by aluminum particles coated with a magnesium-aluminum eutectic alloy (ALCAL). The purpose of the present investigation was to evaluate the possibility of improving the combustion efficiency of these propellants by admixing the eutectic with the aluminum rather than coating the aluminum. Tests of three propellants similar in every respect except for the metal fuel were conducted in test motors with 4.54 kg (10 lbm) of propellant. The first propellant used aluminum fuel; the second contained aluminum admixed with magnesium-aluminum eutectic; the third used ALCAL. The test results show the the admixed fuel gave better low burning-rate combustion efficiency than the other two. The test results also showed that the ALCAL was deficient in that much, if not all, of the coating material could be found as the fine particles in a bimodal mix of aluminum and eutectic. The combustion efficiency of low burning-rate aluminized propellants can be significantly improved by mixing a small amount of magnesium-aluminum alloy with the aluminum fuel.

  16. Cordierite-spinel troctolite, a new magnesium-rich lithology from the lunar highlands

    NASA Technical Reports Server (NTRS)

    Marvin, Ursula B.; Carey, J. William; Lindstrom, Marilyn M.

    1989-01-01

    A clast of spineltroctolite containing 8 percent cordierite (Mg2,Al4Si5O18) has been identified among the constituents of Apollo 15 regolith breccia 15295. The cordierite and associated anorthite, forsteritic olivine, and pleonaste spinel represent a new, Mg-rich lunar highlands lithology that formed by metamorphism of an igneous spinel cumulate. The cordierite-forsterite pair in the assemblage is stable at a maximum pressure of 2.5 kilobars, equivalent to a depth of 50 kilometers, or 10 kilometers above the lunar crust-mantle boundary. The occurrence of the clast indicates that spinel cumulates are a more important constituent of the lower lunar crust than has been recognized. The rarity of cordierite-spinel troctolite among lunar rock samples suggests that it is excavated only by large impact events, such as the one that formed the adjacent Imbrium Basin.

  17. Direct Observation of Reversible Magnesium Ion Intercalation into a Spinel Oxide Host

    SciTech Connect

    Kim, Chunjoong; Phillips, Patrick J.; Key, Baris; Yi, Tanghong; Nordlund, Dennis; Yu, Young-Sang; Bayliss, Ryan D.; Han, Sang-Don; He, Meinan; Zhang, Zhengcheng; Burrell, Anthony K.; Klie, Robert F.; Cabana, Jordi

    2015-06-10

    Direct evidence of Mg2+ intercalation into a spinel-type Mn2O4 is provided. By com­bining tools with different sensitivities, from atomic-resolution X-ray spectro­scopy to bulk X-ray diffraction, it is demonstrated that Mg2+ reversibly occupies the tetrahedral sites of the spinel structure through the reduction of Mn when the electrochemical reaction is performed.

  18. UV fluorescence lifetime modification by aluminum and magnesium nanoapertures

    NASA Astrophysics Data System (ADS)

    Wang, Yunshan; Jiao, Xiaojin; Peterson, Eric M.; Harris, Joel M.; Appusamy, Kanagasundar; Guruswamy, Sivaraman; Blair, Steve

    2016-09-01

    Ultra-violet (UV) fluorescence lifetime modification by aluminum (Al) and magnesium (Mg) nanoapertures are reported in this manuscript. Nanoapertures with diameter ranging from 30nm to 90nm are fabricated using focused ion beam (FIB). Largest lifetime reduction are observed for apertures with smallest diameters and undercuts into glass substrate. For Al nanoapertures, largest lifetime reduction is 5.30×, larger than perviously reported 3.50×.1 For Mg nanoapertures, largest lifetime reduction is 6.90×, which is the largest lifetime reduction of UV fluorescence dye reported so far in literature. The dependence of count rate per molecule (CRM) on aperture size and undercut is also investigated, revealing that CRM increases with increasing undercut, however, the CRM is small (less than 2) for the entire range of aperture size and undercut we investigated. FDTD simulation were conducted and in order to favorably compare experimental results with simulated results, it is critical to take into account the exact shape and material properties of the nano aperture. Simulation results revealed the fundamental difference between Al and Mg nano aperture under 266nm illumination-Mg nano aperture presents a waveguide mode in which the maximum field enhancement and Purcell factor is within the nano aperture instead of on the surface which is the case for Al nano aperture.

  19. Magnesium Rich Primer for Chrome Free Protection of Aluminum Alloys (Preprint)

    DTIC Science & Technology

    2007-12-01

    the solubility of aluminum oxide and its hydrates (FIGURE 4), one can’t help but wonder if the ability to maintain a local pH near neutrality is an...FIGURE 4 – Solubility of aluminum oxide and its hydrates as a function of pH.8 7 QUALIFICATION AND TRANSITION PLAN The preliminary results...AFRL-RX-WP-TP-2008-4012 MAGNESIUM RICH PRIMER FOR CHROME FREE PROTECTION OF ALUMINUM ALLOYS (Preprint) Joel A. Johnson Nonstructural

  20. Chemical and electrical properties of interfaces between magnesium and aluminum and tris-(8-hydroxy quinoline) aluminum

    NASA Astrophysics Data System (ADS)

    Shen, C.; Kahn, A.; Schwartz, J.

    2001-01-01

    The chemistry, electronic structure, and electron injection characteristics at interfaces formed between tris(8-hydroxy quinoline) aluminum (Alq3) and magnesium (Mg) and aluminum (Al) are studied via x-ray photoemission spectroscopy, ultraviolet photoemission spectroscopy, and current-voltage (I-V) measurements. Both metal-on-Alq3 and Alq3-on-metal interfaces are investigated. All interfaces are fabricated and tested in ultrahigh vacuum in order to eliminate extrinsic effects related to interface contamination. The propensity for Mg and Al to form covalent metal-carbon bonds leads to broad and heavily reacted interfaces when the metal is deposited on the organic film. For this deposition sequence, we propose the formation of an organometallic structure where a single metal atom attaches to the pyridyl side of the quinolate ligand of the molecule and coordinates with an oxygen atom of another ligand or of a neighboring molecule. The other deposition sequence leads to significantly more abrupt interfaces where the chemical reaction is limited to the first molecular layer in contact with the metal surface. Both types of interface exhibit chemistry-induced electronic gap states, the position of which depends on the chemical structure of the interface. The interface width, chemical structure, and electronic states appear to play no significant role in electron injection in metal/Alq3/metal sandwich structures, the I-V characteristics for top and bottom injection being identical over several decades of current.

  1. Method for thermal processing alumina-enriched spinel single crystals

    DOEpatents

    Jantzen, Carol M.

    1995-01-01

    A process for age-hardening alumina-rich magnesium aluminum spinel to obtain the desired combination of characteristics of hardness, clarity, flexural strength and toughness comprises selection of the time-temperature pair for isothermal heating followed by quenching. The time-temperature pair is selected from the region wherein the precipitate groups have the characteristics sought. The single crystal spinel is isothermally heated and will, if heated long enough pass from its single phase through two pre-precipitates and two metastable precipitates to a stable secondary phase precipitate within the spinel matrix. Quenching is done slowly at first to avoid thermal shock, then rapidly.

  2. Method for thermal processing alumina-enriched spinel single crystals

    DOEpatents

    Jantzen, C.M.

    1995-05-09

    A process for age-hardening alumina-rich magnesium aluminum spinel to obtain the desired combination of characteristics of hardness, clarity, flexural strength and toughness comprises selection of the time-temperature pair for isothermal heating followed by quenching. The time-temperature pair is selected from the region wherein the precipitate groups have the characteristics sought. The single crystal spinel is isothermally heated and will, if heated long enough pass from its single phase through two pre-precipitates and two metastable precipitates to a stable secondary phase precipitate within the spinel matrix. Quenching is done slowly at first to avoid thermal shock, then rapidly. 12 figs.

  3. Electrolytic conditioning of a magnesium aluminum chloride complex for reversible magnesium deposition

    SciTech Connect

    Barile, Christopher J.; Barile, Elizabeth C.; Zavadil, Kevin R.; Nuzzo, Ralph G.; Gewirth, Andrew A.

    2014-12-04

    We describe in this report the electrochemistry of Mg deposition and dissolution from the magnesium aluminum chloride complex (MACC). The results define the requirements for reversible Mg deposition and definitively establish that voltammetric cycling of the electrolyte significantly alters its composition and performance. Elemental analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy (SEM-EDS) results demonstrate that irreversible Mg and Al deposits form during early cycles. Electrospray ionization-mass spectrometry (ESI-MS) data show that inhibitory oligomers develop in THF-based solutions. These oligomers form via the well-established mechanism of a cationic ring-opening polymerization of THF during the initial synthesis of the MACC and under resting conditions. In contrast, MACC solutions in 1,2-dimethoxyethane (DME), an acyclic solvent, do not evolve as dramatically at open circuit potential. Furthermore, we propose a mechanism describing how the conditioning process of the MACC in THF improves its performance by both tuning the Mg:Al stoichiometry and eliminating oligomers.

  4. Electrolytic conditioning of a magnesium aluminum chloride complex for reversible magnesium deposition

    DOE PAGES

    Barile, Christopher J.; Barile, Elizabeth C.; Zavadil, Kevin R.; ...

    2014-12-04

    We describe in this report the electrochemistry of Mg deposition and dissolution from the magnesium aluminum chloride complex (MACC). The results define the requirements for reversible Mg deposition and definitively establish that voltammetric cycling of the electrolyte significantly alters its composition and performance. Elemental analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy (SEM-EDS) results demonstrate that irreversible Mg and Al deposits form during early cycles. Electrospray ionization-mass spectrometry (ESI-MS) data show that inhibitory oligomers develop in THF-based solutions. These oligomers form via the well-established mechanism of a cationic ring-opening polymerization of THF during the initial synthesis of the MACC andmore » under resting conditions. In contrast, MACC solutions in 1,2-dimethoxyethane (DME), an acyclic solvent, do not evolve as dramatically at open circuit potential. Furthermore, we propose a mechanism describing how the conditioning process of the MACC in THF improves its performance by both tuning the Mg:Al stoichiometry and eliminating oligomers.« less

  5. Impurity control and corrosion resistance of magnesium-aluminum alloy

    SciTech Connect

    Liu, M.; Song, GuangLing

    2013-01-01

    The corrosion resistance of magnesium alloys is very sensitive to the contents of impurity elements such as iron. In this study, a series of diecast AXJ530 magnesium alloy samples were prepared with additions of Mn and Fe. Through a comprehensive phase diagram calculation and corrosion evaluation, the mechanisms for the tolerance limit of Fe in magnesium alloy are discussed. This adds a new dimension to control the alloying impurity in terms of alloying composition design and casting conditions.

  6. Copper stabilization via spinel formation during the sintering of simulated copper-laden sludge with aluminum-rich ceramic precursors.

    PubMed

    Tang, Yuanyuan; Chui, Stephen Sin-Yin; Shih, Kaimin; Zhang, Lingru

    2011-04-15

    The feasibility of incorporating copper-laden sludge into low-cost ceramic products, such as construction ceramics, was investigated by sintering simulated copper-laden sludge with four aluminum-rich ceramic precursors. The results indicated that all of these precursors (γ-Al(2)O(3), corundum, kaolinite, mullite) could crystallochemically stabilize the hazardous copper in the more durable copper aluminate spinel (CuAl(2)O(4)) structure. To simulate the process of copper transformation into a spinel structure, CuO was mixed with the four aluminum-rich precursors, and fired at 650-1150 °C for 3 h. The products were examined using powder X-ray diffraction (XRD) and scanning electron microscopic techniques. The efficiency of copper transformation among crystalline phases was quantitatively determined through Rietveld refinement analysis of the XRD data. The sintering experiment revealed that the optimal sintering temperature for CuAl(2)O(4) formation was around 1000 °C and that the efficiency of copper incorporation into the crystalline CuAl(2)O(4) structure after 3 h of sintering ranged from 40 to 95%, depending on the type of aluminum precursor used. Prolonged leaching tests were carried out by using acetic acid with an initial pH value of 2.9 to leach CuO and CuAl(2)O(4) samples for 22 d. The sample leachability analysis revealed that the CuAl(2)O(4) spinel structure was more superior to stabilize copper, and suggested a promising and reliable technique for incorporating copper-laden sludge or its incineration ash into usable ceramic products. Such results also demonstrated the potential of a waste-to-resource strategy by using waste materials as part of the raw materials with the attainable temperature range used in the production of ceramics.

  7. Corrosion resistance of aluminum-magnesium alloys in glacial acetic acid

    SciTech Connect

    Zaitseva, L.V.; Romaniv, V.I.

    1984-05-01

    Vessels for the storage and conveyance of glacial acetic acid are produced from ADO and AD1 aluminum, which are distinguished by corrosion resistance, weldability and workability in the hot and cold conditions but have low tensile strength. Aluminum-magnesium alloys are stronger materials close in corrosion resistance to technical purity aluminum. An investigation was made of the basic alloying components on the corrosion resistance of these alloys in glacial acetic acid. Both the base metal and the weld joints were tested. With an increase in temperature the corrosion rate of all of the tested materials increases by tens of times. The metals with higher magnesium content show more pitting damage. The relationship of the corrosion resistance of the alloys to magnesium content is confirmed by the similar intensity of failure of the joint metal of all of the investigated alloys and by electrochemical investigations. The data shows that AMg3 alloy is close to technically pure ADO aluminum. However, the susceptibility of even this material to local corrosion eliminates the possibility of the use of aluminum-magnesium alloys as reliable constructional materials in glacial acetic acid.

  8. An Aluminum Magnesium Hydroxide Stearate-based Skin Barrier Protection Cream Used for the Management of Eczematous Dermatitis: A Summary of Completed Studies.

    PubMed

    Del Rosso, James Q; Bhambri, Sanjay; Michaels, Brent

    2008-11-01

    Eczematous dermatoses can often be very difficult to treat. An aluminum magnesium hydroxide stearate-based cream has recently become available for clinical use. Aluminum magnesium hydroxide stearate-based cream provides an alternative option in treating these dermatoses while providing barrier protection against external allergens and irritants. This article reviews various studies evaluating aluminum magnesium hydroxide stearate-based cream.

  9. Improved Interfacial Bonding in Magnesium/Aluminum Overcasting Systems by Aluminum Surface Treatments

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Chen, Yiqing; Luo, Alan A.

    2014-12-01

    "Overcasting" technique is used to produce bimetallic magnesium/aluminum (Mg/Al) structures where lightweight Mg can be cast onto solid Al substrates. An inherent difficulty in creating strong Mg/Al interfacial bonding is the natural oxide film on the solid Al surfaces, which reduces the wettability between molten Mg and Al substrates during the casting process. In the paper, an "electropolishing + anodizing" surface treatment has been developed to disrupt the oxide film on a dilute Al-0.08 wt pct Ga alloy, improving the metallurgical bonding between molten Mg and Al substrates in the bimetallic experiments carried out in a high-vacuum test apparatus. The test results provided valuable information of the interfacial phenomena of the Mg/Al bimetallic samples. The results show significantly improved metallurgical bonding in the bimetallic samples with "electropolishing + anodizing" surface treatment and Ga alloying. It is recommended to adjust the pre-heating temperature and time of the Al substrates and the Mg melt temperature to control the interfacial reactions for optimum interfacial properties in the actual overcasting processes.

  10. On the Utility of Spinel Oxide Hosts for Magnesium-Ion Batteries.

    PubMed

    Knight, James C; Therese, Soosairaj; Manthiram, Arumugam

    2015-10-21

    There is immense interest to develop Mg-ion batteries, but finding suitable cathode materials has been a challenge. The spinel structure has many advantages for ion insertion and has been successfully used in Li-ion batteries. We present here findings on the attempts to extract Mg from MgMn2O4-based spinels with acid (H2SO4) and with NO2BF4. The acid treatment was able to fully remove all Mg from MgMn2O4 by following a mechanism involving the disproportionation of Mn(3+), and the extraction rate decreased with increasing cation disorder. Samples with additional Mg(2+) ions in the octahedral sites (e.g., Mg1.1Mn1.9O4 and Mg1.5Mn1.5O4) also exhibit complete or near complete demagnesiation due to an additional mechanism involving ion exchange of Mg(2+) by H(+), but no Mg could be extracted from MgMnAlO4 due to the disruption of Mn-Mn interaction/contact across shared octahedral edges. In contrast, no Mg could be extracted with the oxidizing agent NO2BF4 from MgMn2O4 or Mg1.5Mn1.5O4 as the electrostatic repulsion between the divalent Mg(2+) ions prevents Mg(2+) diffusion through the 16c octahedral sites, unlike Li(+) diffusion, suggesting that spinels may not serve as potential hosts for Mg-ion batteries. The ability to extract Mg with acid in contrast to that with NO2BF4 is attributed to Mn dissolution from the lattice and the consequent reduction in electrostatic repulsion. The findings could provide insights toward the design of Mg hosts for Mg-ion batteries.

  11. In vivo stimulation of bone formation by aluminum and oxygen plasma surface-modified magnesium implants.

    PubMed

    Wong, Hoi Man; Zhao, Ying; Tam, Vivian; Wu, Shuilin; Chu, Paul K; Zheng, Yufeng; To, Michael Kai Tsun; Leung, Frankie K L; Luk, Keith D K; Cheung, Kenneth M C; Yeung, Kelvin W K

    2013-12-01

    A newly developed magnesium implant is used to stimulate bone formation in vivo. The magnesium implant after undergoing dual aluminum and oxygen plasma implantation is able to suppress rapid corrosion, leaching of magnesium ions, as well as hydrogen gas release from the biodegradable alloy in simulated body fluid (SBF). No released aluminum is detected from the SBF extract and enhanced corrosion resistance properties are confirmed by electrochemical tests. In vitro studies reveal enhanced growth of GFP mouse osteoblasts on the aluminum oxide coated sample, but not on the untreated sample. In addition to that a small amount (50 ppm) of magnesium ions can enhance osteogenic differentiation as reported previously, our present data show a low concentration of hydrogen can give rise to the same effect. To compare the bone volume change between the plasma-treated magnesium implant and untreated control, micro-computed tomography is performed and the plasma-treated implant is found to induce significant new bone formation adjacent to the implant from day 1 until the end of the animal study. On the contrary, bone loss is observed during the first week post-operation from the untreated magnesium sample. Owing to the protection offered by the Al2O3 layer, the plasma-treated implant degrades more slowly and the small amount of released magnesium ions stimulate new bone formation locally as revealed by histological analyses. Scanning electron microscopy discloses that the Al2O3 layer at the bone-implant interface is still present two months after implantation. In addition, no inflammation or tissue necrosis is observed from both treated and untreated implants. These promising results suggest that the plasma-treated magnesium implant can stimulate bone formation in vivo in a minimal invasive way and without causing post-operative complications.

  12. Quasi-planar homopolymetallic and heteropolymetallic coordination arrays. Surface-like molecular clusters of magnesium and aluminum.

    PubMed

    Fujita, Megumi; Lightbody, Owen C; Ferguson, Michael J; McDonald, Robert; Stryker, Jeffrey M

    2009-04-08

    The sterically isolated preorganized tetradentate ligand systems, tetrakis(2-hydroxy-3-n-propylphenyl)ethene and tetrakis(5-tert-butyl-2-hydroxy-3-trimethylsilylphenyl)ethene, nucleate the formation of quasi-planar raft-like polymetallic coordination complexes with high selectivity, providing topologically consistent structural models for metal coordination to the "oxo-surface" of silica- and alumina-supported heterogeneous catalysts. The coordination of magnesium salts to these systems yields trimetallic magnesium halide and alkyl complexes arrayed on the oxygen "surface" of the ligand, regardless of the steric profile of the ortho-substituents. The magnesium complexes, characterized in the solid state by X-ray crystallography, contain two chemically distinct metal environments, a relatively inert central magnesium bis(alkoxide) and two more labile pseudotetrahedral "wing" magnesium atoms. The central metal coordination is pseudo-octahedral; crystallography strongly suggests the presence of an unprecedented dative magnesium-olefin bonding interaction from the metal to ethene bridge of the ligand. Consistent with the chemistry proposed for typical magnesium-treated catalyst supports, the labile wing magnesium centers can be cleanly and sequentially exchanged for aluminum with retention of the surface-like coordination array. Thus, treatment with diethylaluminum chloride provides heterotrimetallic magnesium-aluminum complexes containing one aluminum and two magnesium sites or two aluminum and one magnesium site, respectively. All four heteropolymetallic complexes have been characterized by X-ray crystallography.

  13. Radiation-induced luminescence in magnesium aluminate spinel crystals and ceramics

    NASA Astrophysics Data System (ADS)

    Gritsyna, V. T.; Kazarinov, Yu. G.; Kobyakov, V. A.; Reimanis, I. E.

    2006-09-01

    Radioluminescence (RL) and thermoluminescence (TL) in spinel crystals and ceramics were investigated to elucidate the radiation-induced electronic processes in single crystals grown by Verneuil and Czochralski methods as well as transparent and translucent ceramics. Both RL and TL spectra demonstrate a UV-band related to electron-hole recombination luminescence at intrinsic defects; green and red luminescence are identified with emission of Mn 2+- and Cr 3+-ions, respectively. The kinetics of growth of different RL luminescence bands depending on dose at the prolonged X-irradiation shows the competitive character of charge and energy transfer between defects and impurity ions. The dependence of RL intensity on the temperature of the sample was measured in the range of 300-750 K and compared with TL for different emission bands. The variety of maxima in the temperature dependence of RL and in the glow curves of TL measured for different luminescence bands in spinels of different origins and crystalline forms is used to show that charge carrier traps and luminescence centers are not isolated defects but are complexes of defects and impurities. The formation, structure and properties of these complexes depend on the processing conditions.

  14. Rain Erosion Studies of Sapphire, Aluminum Oxynitride, Spinel, Lanthana- Doped Yttria, and TAF Glass

    DTIC Science & Technology

    1990-07-01

    spinel samples run at NADC were examined by eye and the most damaged one had three obvious nicks In it. Figure 1 Is a photograph of the disk at very low...Institute, Dayton, OR (C. J. Harley ) 1 Westinghouse Electronics Corporation, Defense and Electronics Systes Center, Baltimo, MD (Dr, S. J. Bepko) 2

  15. X-ray structural study of chrome-aluminum lunar spinel from the Sea of Fertility

    NASA Technical Reports Server (NTRS)

    Nozik, Y. Z.; Tovbis, A. B.

    1974-01-01

    An X-ray structural study was made of a lunar spinel sample from the Sea of Fertility. The chemical composition and distribution of cations in the structure were characterized. Interpretation of the experimental data by the least squares method yielded the oxygen parameter u = 0.261 and the isotropic temperature factor 1.09 AU squared.

  16. Substitution of Aluminum for Magnesium as a Fuel in Flares

    DTIC Science & Technology

    1975-01-01

    silicon dioxide (Superflois, Johns - Manville Company) could be employed to produce desirable per- formance chr racteristics. It was found that the... Johns - Manville Company (’ab-()-Sil (S;O), MS-7, Cabot Corporation Magnesium, atomized, 30/50 mesh, Specification MIL-P-l4067B3, Hart Metals Incorporated

  17. Spinel formation for stabilizing simulated nickel-laden sludge with aluminum-rich ceramic precursors.

    PubMed

    Shih, Kaimin; White, Tim; Leckie, James O

    2006-08-15

    The feasibility of stabilizing nickel-laden sludge from commonly available Al-rich ceramic precursors was investigated and accomplished with high nickel incorporation efficiency. To simulate the process, nickel oxide was mixed alternatively with gamma-alumina, corundum, kaolinite, and mullite and was sintered from 800 to 1480 degrees C. The nickel aluminate spinel (NiAl2O4) was confirmed as the stabilization phase for nickel and crystallized with efficiencies greater than 90% for all precursors above 1250 degrees C and 3-h sintering. The nickel-incorporation reaction pathways with these precursors were identified, and the microstructure and spinel yield were investigated as a function of sintering temperature with fixed sintering time. This study has demonstrated a promising process for forming nickel spinel to stabilize nickel-laden sludge from a wide range of inexpensive ceramic precursors, which may provide an avenue for economically blending waste metal sludges via the building industry processes to reduce the environmental hazards of toxic metals. The correlation of product textures and nickel incorporation efficiencies through selection of different precursors also provides the option of tailoring property-specific products.

  18. Studies on densification, mechanical, micro-structural and structure–properties relationship of magnesium aluminate spinel refractory aggregates prepared from Indian magnesite

    SciTech Connect

    Ghosh, Chandrima; Ghosh, Arup; Haldar, Manas Kamal

    2015-01-15

    The present work intends to study the development of magnesium aluminate spinel aggregates from Indian magnesite in a single firing stage. The raw magnesite has been evaluated in terms of chemical analysis, differential thermal analysis, thermogravimetric analysis, infrared spectroscopy, and X-ray diffraction. The experimental batch containing Indian magnesite and calcined alumina has been sintered in the temperature range of 1550 °C–1700 °C. The sintered material has been characterized in terms of physico-chemical properties like bulk density, apparent porosity, true density, relative density and thermo-mechanical/mechanical properties like hot modulus of rupture, thermal shock resistance, cold modulus of rupture and structural properties by X-ray diffraction in terms of phase identification and evaluation of crystal structure parameters of corresponding phases by Rietveld analysis. The microstructures developed at different temperatures have been analyzed by field emission scanning electron microscope study and compositional analysis of the developed phase has been carried out by energy dispersive X-ray study. - Highlights: • The studies have been done to characterize the developed magnesium aluminate spinel. • The studies reveal correlation between refractory behavior of spinel and developed microstructures. • The studies show the values of lattice parameters of developed phases.

  19. Laser Surface Alloying of Copper, Manganese, and Magnesium with Pure Aluminum Substrate

    NASA Astrophysics Data System (ADS)

    Jiru, Woldetinsay G.; Sankar, M. Ravi; Dixit, Uday S.

    2016-03-01

    Laser surface alloying is one of the recent technologies used in the manufacturing sector for improving the surface properties of the metals. Light weight materials like aluminum alloys, titanium alloys, and magnesium alloys are used in the locomotive, aerospace, and structural applications. In the present work, an experimental study was conducted to improve the surface hardness of commercially pure aluminum plate. CO2 laser is used to melt pre-placed powders of pure copper, manganese, and magnesium. Microstructure of alloyed surface was analyzed using optical microscope. The best surface alloying was obtained at the optimum values of laser parameters, viz., laser power, scan speed, and laser beam diameter. In the alloyed region, microhardness increased from 30 HV0.5 to 430 HV0.5, while it was 60 HV0.5 in the heat-affected region. Tensile tests revealed some reduction in the strength and total elongation due to alloying. On the other hand, corrosion resistance improved.

  20. Retardation of surface corrosion of biodegradable magnesium-based materials by aluminum ion implantation

    NASA Astrophysics Data System (ADS)

    Wu, Guosong; Xu, Ruizhen; Feng, Kai; Wu, Shuilin; Wu, Zhengwei; Sun, Guangyong; Zheng, Gang; Li, Guangyao; Chu, Paul K.

    2012-07-01

    Aluminum ion implantation is employed to modify pure Mg as well as AZ31 and AZ91 magnesium alloys and their surface degradation behavior in simulated body fluids is studied. Polarization tests performed in conjunction with scanning electron microscopy (SEM) reveal that the surface corrosion resistance after Al ion implantation is improved appreciably. This enhancement can be attributed to the formation of a gradient surface structure with a gradual transition from an Al-rich oxide layer to Al-rich metal layer. Compared to the high Al-content magnesium alloy (AZ91), a larger reduction in the degradation rate is achieved from pure magnesium and AZ31. Our results reveal that the surface corrosion resistance of Mg alloys with no or low Al content can be improved by Al ion implantation.

  1. Intercalation and Push-Out Process with Spinel-to-Rocksalt Transition on Mg Insertion into Spinel Oxides in Magnesium Batteries.

    PubMed

    Okamoto, Shinya; Ichitsubo, Tetsu; Kawaguchi, Tomoya; Kumagai, Yu; Oba, Fumiyasu; Yagi, Shunsuke; Shimokawa, Kohei; Goto, Natsumi; Doi, Takayuki; Matsubara, Eiichiro

    2015-08-01

    On the basis of the similarity between spinel and rocksalt structures, it is shown that some spinel oxides (e.g., MgCo2O4, etc) can be cathode materials for Mg rechargeable batteries around 150 °C. The Mg insertion into spinel lattices occurs via "intercalation and push-out" process to form a rocksalt phase in the spinel mother phase. For example, by utilizing the valence change from Co(III) to Co(II) in MgCo2O4, Mg insertion occurs at a considerably high potential of about 2.9 V vs. Mg(2+)/Mg, and similarly it occurs around 2.3 V vs. Mg(2+)/Mg with the valence change from Mn(III) to Mn(II) in MgMn2O4, being comparable to the ab initio calculation. The feasibility of Mg insertion would depend on the phase stability of the counterpart rocksalt XO of MgO in Mg2X2O4 or MgX3O4 (X = Co, Fe, Mn, and Cr). In addition, the normal spinel MgMn2O4 and MgCr2O4 can be demagnesiated to some extent owing to the robust host structure of Mg1-xX2O4, where the Mg extraction/insertion potentials for MgMn2O4 and MgCr2O4 are both about 3.4 V vs. Mg(2+)/Mg. Especially, the former "intercalation and push-out" process would provide a safe and stable design of cathode materials for polyvalent cations.

  2. Crystal structure of complex natural aluminum magnesium calcium iron oxide

    SciTech Connect

    Rastsvetaeva, R. K. Aksenov, S. M.; Verin, I. A.

    2010-07-15

    The structure of a new natural oxide found near the Tashelga River (Eastern Siberia) was studied by X-ray diffraction. The pseudo-orthorhombic unit cell parameters are a = 5.6973(1) A, b = 17.1823(4) A, c = 23.5718(5) A, {beta} = 90{sup o}, sp. gr. Pc. The structure was refined to R = 0.0516 based on 4773 reflections with vertical bar F vertical bar > 7{sigma}(F) taking into account the twin plane perpendicular to the z axis (the twin components are 0.47 and 0.53). The crystal-chemical formula (Z = 4) is Ca{sub 2}Mg{sub 2}{sup IV}Fe{sub 2}{sup (2+)IV}[Al{sub 14}{sup VI}O{sub 31}(OH)][Al{sub 2}{sup IV}O][Al{sup IV}]AL{sup IV}(OH)], where the Roman numerals designate the coordination of the atoms. The structure of the mineral is based on wide ribbons of edge-sharing Al octahedra (an integral part of the spinel layer). The ribbons run along the shortest x axis and are inclined to the y and z axes. The adjacent ribbons are shifted with respect to each other along the y axis, resulting in the formation of step-like layers in which the two-ribbon thickness alternates with the three-ribbon thickness. Additional Al octahedra and Mg and Fe{sup 2+} tetrahedra are located between the ribbons. The layers are linked together to form a three-dimensional framework by Al tetrahedra, Ca polyhedra, and hydrogen bonds with the participation of OH groups.

  3. The simultaneous removal of calcium, magnesium and chloride ions from industrial wastewater using magnesium-aluminum oxide.

    PubMed

    Hamidi, Roya; Kahforoushan, Davood; Fatehifar, Esmaeil

    2013-01-01

    In this article, a method for simultaneous removal of calcium, magnesium and chloride by using Mg0.80Al0.20O1.10 as a Magnesium-Aluminum oxide (Mg‒Al oxide) was investigated. Mg‒Al oxide obtained by thermal decomposition of the Mg-Al layered double hydroxide (Mg-Al LDH). The synthesized Mg‒Al oxide were characterized with respect to nitrogen physicosorption, X-ray diffraction (XRD) and field emission scan electron microscopy (FESEM) morphology. Due to high anion-exchange capacity of Mg‒Al oxide, it was employed in simultaneously removal of Cl(-), Mg(+2) and Ca(+2) from distiller waste of a sodium carbonate production factory. For this purpose, experiments were designed to evaluate the effects of quantity of Mg‒Al oxide, temperature and time on the removal process. The removal of Cl(-), Mg(+2) and Ca(+2) from wastewater was found 93.9%, 93.74% and 93.25% at 60°C after 0.5 h, respectively. Results showed that the removal of Cl(-), Mg(+2) and Ca(+2) by Mg‒Al oxide increased with increasing temperature, time and Mg‒Al oxide quantity.

  4. On the role of magnesium and silicon in the formation of alumina from aluminum alloys by means of DIMOX processing

    NASA Astrophysics Data System (ADS)

    Yang, Liu; Zhu, Degui; Xu, Changqing; Zhang, Jun; Zhang, Jian

    1996-08-01

    This article deals with the reaction mechanisms of the DIMOX (Directed Melt Oxided) processing of aluminum alloys. An orthogonalized experimental procedure was introduced to stipulate the effects of the reaction temperature, reaction time, and additional metallic elements, magnesium and silicon, on the oxidation process of aluminum alloys. Emphasis is placed on the distribution of magnesium and silicon in the products so that the behaviors of these two crucial elements for the formation of alumina from directed oxidation of aluminum alloys could be revealed. Alterative methods, including optical and scanning electron microscopy (SEM), electron probing, and wave spectrum analysis were applied to specify the microstructure characters of the products and locate the position of both magnesium and silicon in the reaction products. Judged by the weight gain after reaction, the results indicated that the temperature is the most influential factor in controlling the oxidation kinetics. Silicon is more effective than magnesium in accelerating the process, although magnesium is indispensable for the process to take place. While judged by the morphology of the reaction products, an excessive amount of silicon is harmful to the DIMOX process in that the final products consist of a large amount of porosity. Both magnesium and silicon are rather concentrated in specific regions than homogeneously distributed in the whole products. The contents of magnesium and silicon in the surface region are not as high as expected, with most of the magnesium being concentrated in the region directly neighboring the bulky metals and most of the Si in the residual bulky metals, although the contents of these two elements in the surface region are a little higher than the regions next to the surface. These characteristics, combined with other investigations, suggest that the decisive role of the slight amount of magnesium and silicon in the nucleation and growth of Al2O3 could be explained by

  5. Convenient method of simultaneously analyzing aluminum and magnesium in pharmaceutical dosage forms using californium-252 thermal neutron activation.

    PubMed

    Landolt, R R; Hem, S L

    1983-05-01

    A commercial antacid suspension containing aluminum hydroxide and magnesium hydroxide products was used as a model sample to study the use of a californium-252 thermal neutron activation as a method for quantifying aluminum content as well as for the simultaneous assay of aluminum and magnesium. A 3.5-micrograms californium-252 source was used for the activation, and the induced aluminum-28 and magnesium-27 activity was simultaneously measured by sodium iodide crystal gamma-ray spectrometry using dual single-channel analyzers and scalers. The antacid suspension was contained in a chamber designed with the unique capability of serving as the container for counting the induced radioactivity in addition to being the irradiation chamber itself. Ten replicate irradiations were performed, and the precision was compared with 10 replicate analyses of the antacid suspension using the official ethylenediaminetetraacetic acid titration method. For aluminum the precision was 1.4 versus 0.62% for the titration method. For the magnesium the precision was 5.3 versus 0.79% for the titration method. This pilot study demonstrated that use of more intense californium-252 sources, which are commonly available, would provide a method that is competitive with the ethylenediaminetetraacetic acid titration method in precision and in other aspects as well.

  6. Magnesium, Iron and Aluminum in LLNL Air Particulate and Rain Samples with Reference to Magnesium in Industrial Storm Water

    SciTech Connect

    Esser, Bradley K.; Bibby, Richard K.; Fish, Craig

    2016-08-25

    Storm water runoff from the Lawrence Livermore National Laboratory’s (LLNL’s) main site and Site 300 periodically exceeds the Discharge Permit Numeric Action Level (NAL) for Magnesium (Mg) under the Industrial General Permit (IGP) Order No. 2014-0057-DWQ. Of particular interest is the source of magnesium in storm water runoff from the site. This special study compares new metals data from air particulate and precipitation samples from the LLNL main site and Site 300 to previous metals data for storm water from the main site and Site 300 and alluvial sediment from the main site to investigate the potential source of elevated Mg in storm water runoff. Data for three metals (Mg, Iron {Fe}, and Aluminum {Al}) were available from all media; data for additional metals, such as Europium (Eu), were available from rain, air particulates, and alluvial sediment. To attribute source, this study compared metals concentration data (for Mg, Al, and Fe) in storm water and rain; metal-metal correlations (Mg with Fe, Mg with Al, Al with Fe, Mg with Eu, Eu with Fe, and Eu with Al) in storm water, rain, air particulates, and sediments; and metal-metal ratios ((Mg/Fe, Mg/Al, Al/Fe, Mg/Eu, Eu/Fe, and Eu/Al) in storm water, rain, air particulates and sediments. The results presented in this study are consistent with a simple conceptual model where the source of Mg in storm water runoff is air particulate matter that has dry-deposited on impervious surfaces and subsequently entrained in runoff during precipitation events. Such a conceptual model is consistent with 1) higher concentrations of metals in storm water runoff than in precipitation, 2) the strong correlation of Mg with Aluminum (Al) and Iron (Fe) in both storm water and air particulates, and 3) the similarity in metal mass ratios between storm water and air particulates in contrast to the dissimilarity of metal mass ratios between storm water and precipitation or alluvial sediment. The strong correlation of Mg with Fe and Al

  7. Self-diffusion of magnesium in spinel and in equilibrium melts - Constraints on flash heating of silicates

    NASA Technical Reports Server (NTRS)

    Sheng, Y. J.; Wasserburg, G. J.; Hutcheon, I. D.

    1992-01-01

    An isotopic tracer is used to measure Mg self-diffusion in spinel and coexisting melt at bulk chemical equilibrium. The diffusion coefficients were calculated from the measured isotope profiles using a model that includes the complementary diffusion of Mg-24, Mg-25, and Mg-26 in both phases with the constraint that the Mg content of each phase is constant. The activation energy and preexponential factor for Mg self-diffusion in spinel are, respectively, 384 +/- 7 kJ and 74.6 +/- 1.1 sq cm/s. These data indicate Mg diffusion in spinel is much slower than previous estimates. The activation energy for Mg self-diffusion in coexisting melt is 343 +/- 25 kJ and the preexponential factor is 7791.9 +/- 1.3 sq cm/s. These results are used to evaluate cooling rates of plagioclase-olivine inclusions (POIs) in the Allende meteorite. Given a maximum melting temperature for POIs of about 1500 C, these results show that a 1-micron radius spinel would equilibrate isotopically with a melt within about 60 min.

  8. On the role of magnesium and silicon in the formation of alumina from aluminum alloys by means of DIMOX processing

    SciTech Connect

    Yang, L.; Zhu, D.; Xu, C.; Zhang, J.; Zhang, J.

    1996-08-01

    This article deals with the reaction mechanisms of the DIMOX (Directed Melt Oxided) processing of aluminum alloys. An orthogonalized experimental procedure was introduced to stipulate the effects of the reaction temperature, reaction time, and additional metallic elements, magnesium and silicon, on the oxidation process of aluminum alloys. Emphasis is placed on the distribution of magnesium and silicon in the products so that the behaviors of these two crucial elements for the formation of alumina from directed oxidation of aluminum alloys could be revealed. Alterative methods, including optical and scanning electron microscopy (SEM), electron probing, and wave spectrum analysis were applied to specify the microstructure characters of the products and locate the position of both magnesium and silicon in the reaction products. Judged by the weight gain after reaction, the results indicated that the temperature is the most influential factor in controlling the oxidation kinetics. Both magnesium and silicon are rather concentrated in specific regions than homogeneously distributed in the whole products. The contents of magnesium and silicon in the surface region are not as high as expected, and most of the magnesium being concentrated in the region directly neighboring the bulky metals and most of the Si in the residual bulky metals, although the contents of these two elements in the surface region are a little higher than the regions next to the surface. These characteristics, combined with other investigations, suggest that the decisive role of the slight amount of magnesium and silicon in the nucleation and growth of Al{sub 2}O{sub 3} could be explained by the proposed circulated reaction.

  9. Overview of DOE'S programs on aluminum and magnesium for automotive application

    SciTech Connect

    Carpenter, J.; Diamond, S.; Dillich, S.; Fitzsimmons, T.; Milliken, J.; Sklad, P.

    1999-02-28

    The U.S. Department of Energy will present an update and review of its programs in aluminum and magnesium for automotive and heavy-duty vehicle applications. While the main programs focused on vehicle materials are in the Office of Transportation Technologies, contributing efforts will be described in the DOE Office of Industrial Technologies and the DOE Office of Energy Research. The presentation will discuss materials for body/chassis and power train, and will highlight the considerable synergy among the efforts. The bulk of the effort is on castings, sheet, and alloys with a smaller focus on metal matrix composites. Cost reduction and energy savings are the overriding themes of the programs.

  10. Removal of hydrogen chloride from gaseous streams using magnesium-aluminum oxide.

    PubMed

    Kameda, Tomohito; Uchiyama, Naoya; Park, Kye-Sung; Grause, Guido; Yoshioka, Toshiaki

    2008-10-01

    Magnesium-aluminum oxide (Mg-Al oxide) obtained by thermal decomposition of Mg-Al layered double hydroxide (Mg-Al LDH) effectively removed HCl from gaseous streams. HCl removal was greater in the presence of added water vapor at all temperatures examined and increased with decreasing temperature in both the presence and absence of added water vapor. Wet and dry removal of gaseous HCl were attributed to the production of MgCl2 . 6H2O and MgCl2 . 4H2O, respectively. For the wet scrubbing process, the reconstruction reaction of Mg-Al LDH from Mg-Al oxide was the primary mechanism for increased HCl removal.

  11. The effect of magnesium oxide supplementation to aluminum oxide slip on the jointing of aluminum oxide bars.

    PubMed

    Odatsu, Tetsurou; Sawase, Takashi; Kamada, Kohji; Taira, Yohsuke; Shiraishi, Takanobu; Atsuta, Mitsuru

    2008-03-01

    The purpose of this study was to investigate the effect of modifying aluminum oxide slips with magnesium oxide (MgO) to create a jointing material for In-Ceram Alumina. Jointed In-Ceram Alumina bars with In-Ceram Alumina slips containing 0-1.0 mass% MgO were examined by a three-point bending test. Joint-free bars were also tested as controls. Fracture surfaces were evaluated by scanning electron microscopy. In addition, linear shrinkage and fracture toughness were assessed. The 0.3 mass% MgO group showed the highest flexural strength among the jointed groups, and there were no statistical differences between the joint-free control groups. The fracture surface of 0.3 mass% MgO group showed increased sintering densification with reduced micropore size. No linear shrinkage was observed with the addition of MgO to the alumina slip. Added MgO was also effective in boosting fracture toughness. The present findings indicate that the MgO-supplemented binding material is useful for clinical applications.

  12. Alginate-magnesium aluminum silicate films for buccal delivery of nicotine.

    PubMed

    Pongjanyakul, Thaned; Suksri, Hatairat

    2009-11-01

    Sodium alginate-magnesium aluminum silicate (SA-MAS) dispersions with nicotine (NCT) were prepared at different pHs and characterized for the particle size and zeta potential, NCT adsorbed by MAS, and flow behavior before film casting. The physicochemical properties, NCT content, in vitro bioadhesive property, and NCT release and permeation of the NCT-loaded SA-MAS films were investigated. This study showed that incorporation of NCT into the SA-MAS dispersions caused a change in particle size and flow behavior and that NCT could be adsorbed by MAS. The formation of protonated NCT at acidic and neutral pHs could interact with negatively charged MAS via an electrostatic force, resulting in the formation of NCT-MAS flocculates/complexes that could act as microreservoirs in the films. The NCT-loaded SA-MAS films prepared at pH 5 yielded the highest NCT content due to non-significant loss of NCT during drying. Moreover, pH of the preparation also affected the crystallinity and thermal properties of the films. The NCT release and permeation across the mucosal membrane of the films could be described using a matrix diffusion controlled mechanism. In addition, the NCT-loaded SA-MAS films also possessed a bioadhesive property for adhesion to the mucosal membrane. This finding suggests that the NCT-loaded SA-MAS films composed of numerous NCT-MAS complexes as microreservoirs demonstrated a strong potential for use as a buccal delivery system.

  13. Theoretical investigation of the interaction of glycerol with aluminum and magnesium phthalocyanines.

    PubMed

    Silva, V H C; Camargo, L T F M; Napolitano, H B; Pérez, C N; Camargo, A J

    2010-09-01

    Glycerol is a byproduct produced in great quantity by biodiesel industries in transesterification reactions. Finding new applications for glycerol is a current concern of many research groups around the world. This work focuses on a theoretical investigation, at the B3LYP/6-31G* level of theory, into the possibility of using aluminum phthalocyanine (AlPc) and magnesium phthalocyanine (MgPc) in the modelling of catalysts to convert glycerol into alcohol, which has wider industrial applicability. According to our calculations there are strong interactions between the O-terminus of glycerol and the central metal atom of AlPc and MgPc. By applying the Fukui function, HSAB theory and analysis of the frontier molecular orbital, it was possible to explain the way in which glycerol interacts with AlPc and MgPc. As a result of these interactions, there is a considerable change in both electronic and geometric parameters of glycerol, which can be used in designing new strategies to convert glycerol into alcohol.

  14. New method of treating dilute mineral acids using magnesium-aluminum oxide.

    PubMed

    Kameda, Tomohito; Yabuuchi, Fumiko; Yoshioka, Toshiaki; Uchida, Miho; Okuwaki, Akitsugu

    2003-04-01

    Mineral acids, such as H(3)PO(4), H(2)SO(4), HCl, and HNO(3,) were treated with magnesium-aluminum oxide (Mg-Al oxide), which behaved as a neutralizer and fixative of anions. Anion removal increased with increasing Mg-Al oxide quantity, time, Mg/Al molar ratio, and initial acid concentration. Up to 95% removal of anions was achieved in 0.5 N acids using a stoichiometric quantity of Mg(0.80)Al(0.20)O(1.10) for H(3)PO(4), 1.75 stoichiometric quantities for H(2)SO(4), or 2.5 stoichiometric quantities for HCl or HNO(3) at 20 degrees C over a period of 6 h. The final solutions were found to have a pH in the range of 8-12. Selectivity of acid removal was found to follow the following order: H(3)PO(4) > H(2)SO(4) > HCl > HNO(3). The equivalent of acid removal per 1 g of Mg-Al oxide decreased as the Mg/Al molar ratio of Mg-Al oxide increased.

  15. Forge Welding of Magnesium Alloy to Aluminum Alloy Using a Cu, Ni, or Ti Interlayer

    NASA Astrophysics Data System (ADS)

    Yamagishi, Hideki; Sumioka, Junji; Kakiuchi, Shigeki; Tomida, Shogo; Takeda, Kouichi; Shimazaki, Kouichi

    2015-08-01

    The forge-welding process was examined to develop a high-strength bonding application of magnesium (Mg) alloy to aluminum (Al) alloy under high-productivity conditions. The effect of the insert material on the tensile strength of the joints, under various preheat temperatures and pressures, was investigated by analyzing the reaction layers of the bonded interface. The tensile strengths resulting from direct bonding, using pure copper (Cu), pure nickel (Ni), and pure titanium (Ti) inserts were 56, 100, 119, and 151 MPa, respectively. The maximum joint strength reached 93 pct with respect to the Mg cast billet. During high-pressure bonding, a microscopic plastic flow occurred that contributed to an anchor effect and the generation of a newly formed surface at the interface, particularly prominent with the Ti insert in the form of an oxide layer. The bonded interfaces of the maximum-strength inserts were investigated using scanning electron microscopy-energy-dispersive spectroscopy and electron probe microanalysis. The diffusion reaction layer at the bonded interface consisted of brittle Al-Mg intermetallics having a thickness of approximately 30 μm. In contrast, for the three inserts, the thicknesses of the diffusion reaction layer were infinitely thin. For the pure Ti insert, exhibiting the maximum tensile strength value among the inserts tested, focused ion beam-transmission electron microscopy-EDS analysis revealed a 60-nm-thick Al-Ti reaction layer, which had formed at the bonded interface on the Mg alloy side. Thus, a high-strength Al-Mg bonding method in air was demonstrated, suitable for mass production.

  16. Transparent Spinel Ceramic

    DTIC Science & Technology

    2009-01-01

    2009 NRL REVIEW 215 OPTICAL SCIENCES Transparent Spinel Ceramic J.S. Sanghera, G. Villalobos , W. Kim, S. Bayya, and I.D. Aggarwal Optical Sciences...Sponsored by NRL and ONR] Reference 1 G. Villalobos , J.S. Sanghera, S.B. Bayya, and I.D. Aggarwal, “Fluoride Salt Coated Magnesium Aluminate,” U.S. Patent 7,211,325, May 1, 2007.

  17. Effect of an aggressive medium on discontinuous deformation of aluminum-magnesium alloy AlMg6

    NASA Astrophysics Data System (ADS)

    Shibkov, A. A.; Denisov, A. A.; Zolotov, A. E.; Kochegarov, S. S.

    2017-01-01

    It is experimentally shown that the molecular (chemical) process of surface etching of deformed aluminum-magnesium alloy AlMg6 causes the development of a macroscopic plastic strain step with an amplitude of a few percent. Using numerical simulation of the polycrystalline solid etching process, it is shown that the corrosion front morphology varies during etching from Euclid (flat) to fractal (rough). The results obtained show the key role of the surface state on the development of macroscopic mechanical instability of a material exhibiting the Portevin-Le Chatelier effect.

  18. Thermal conductivity of diethylene glycol based magnesium-aluminum spinel (MgAl2O4-DG) nanofluids

    NASA Astrophysics Data System (ADS)

    Żyła, Gaweł; Fal, Jacek; Gizowska, Magdalena; Perkowski, Krzysztof

    2016-12-01

    The paper presents the results of measurements of the thermal conductivity of MgAl_2O_4 -DG nanofluids. The dependence of the thermal conductivity on concentration of nanoparticles in various temperatures from 293.15 to 338.15 K with 15 K step was examined. Experimental data was modeled with existing theoretical models describing the effects of the concentration of particles on the thermal conductivity of the suspension. It was presented that thermal conductivity of MgAl_2O_4 -DG nanofluids increases proportional to volume concentration of nanoparticles.

  19. Surface modification of magnesium aluminum hydroxide nanoparticles with poly(methyl methacrylate) via one-pot in situ polymerization

    NASA Astrophysics Data System (ADS)

    Guo, Xiaojun; Zhao, Leihua; Zhang, Li; Li, Jing

    2012-01-01

    Hydrophobic magnesium aluminum hydroxide composite particles (PMMA-MAH) were obtained by means of grafting poly(methyl methacrylate) (PMMA) onto the surface of magnesium aluminum hydroxide(MAH) nanoparticles after a novel type of phosphate coupling agent (DN-27) modification. The introduction of functional double bonds was firstly conducted on the surface of nanoparticles by DN-27 modification, followed by one-pot in situ polymerization on the particles surface using methyl methacrylate (MMA) as monomer, azoisobutyronitrile (AIBN) as initiator and sodium dodecyl sulfate (SDS) as stabilizer to graft PMMA on the surface of DN-27-modified MAH particles. The obtained composite particles were characterized by field-emission scanning electron microscope (FESEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray powder diffraction (XRD). The results show that the organic macromolecule PMMA could be successfully grafted on the surface of DN-27-modified MAH nanoparticles and the thermal stability of the PMMA-MAH composite particles had been improved. Compared with unmodified blank MAH sample, the product obtained with this method possesses better hydrophobic properties such as a higher water contact angle of 108° and a well dispersion.

  20. Development of a novel aluminum-free glass ionomer cement based on magnesium/strontium-silicate glasses.

    PubMed

    Kim, Dong-Ae; Abo-Mosallam, Hany A; Lee, Hye-Young; Kim, Gyu-Ri; Kim, Hae-Won; Lee, Hae-Hyoung

    2014-09-01

    The effects of strontium substitution for magnesium in a novel aluminum-free multicomponent glass composition for glass ionomer cements (GICs) were investigated. A series of glass compositions were prepared based on SiO2-P2O5-CaO-ZnO-MgO(1-X)-SrOX-CaF2 (X=0, 0.25, 0.5 and 0.75). The mechanical properties of GICs prepared were characterized by compressive strength, flexural strength, flexural modules, and microhardness. Cell proliferation was evaluated indirectly by CCK-8 assay using various dilutions of the cement and rat mesenchyme stem cells. Incorporation of strontium instead of magnesium in the glasses has a significant influence on setting time of the cements and the properties. All mechanical properties of the GICs with SrO substitution at X=0.25 were significantly increased, then gradually decreased with further increase of the amount of strontium substitution in the glass. The GIC at X=0.25, also, showed an improved cell viability at low doses of the cement extracts in comparison with other groups or control without extracts. The results of this study demonstrate that the glass compositions with strontium substitution at low levels can be successfully used to prepare aluminum-free glass ionomer cements for repair and regeneration of hard tissues.

  1. Organosilane self-assembled layers (SAMs) and hybrid silicate magnesium-rich primers for the corrosion protection of aluminum alloy 2024 T3

    NASA Astrophysics Data System (ADS)

    Wang, Duhua

    Although current chromate coatings function very well in corrosion protection for aircraft alloys, such as aluminum alloy 2024 T3, the U.S. Environmental Protection Agency is planning to totally ban the use of chromates as coating materials in the next decade or so because of their extremely toxic effect. For this purpose, both self-assembled layers and silicate magnesium-rich primers were tested to provide the corrosion protection for aluminum alloy. The long-term goal of this research is to develop a coating system to replace the current chromate coating for aircraft corrosion protection. Aluminum alloy 2024 T3 substrates were modified with self-assembled monolayer or multilayer thin films from different alkylsilane compounds. Mono-functional silanes, such as octadecyltrichlorosilane (C18SiCl3), can form a mixed hydrophobic monolayer or multilayer thin film on the aluminum oxide surface to provide a barrier to water and other electrolytes, so the corrosion resistance of the SAMs modified surface was increased significantly. On the other hand, the bi-functional silane self-assembly could attach the aluminum surface through the silicon headgroup while using its functional tailgroup to chemically bond the polymer coating, thus improving the adhesion between the aluminum substrate and coating substantially, and seems to contribute more to corrosion protection of aluminum substrate. Organosilanes were also combined with tetraethyl orthosilicate (TEOS) in propel ratios to form a sol-gel binder to make silicate magnesium-rich primers. Analogue to the inorganic zinc-rich coatings, the silicate magnesium-rich primers also showed excellent adhesion and solvent resistance. The sacrificial magnesium pigments and the chemically inert silicate binder both contribute to the anti-corrosion properties. Future studies will be focused on the formula optimization for better toughness, chemical resistance and anticorrosion performance.

  2. DEGRADATION OF SM2ZR2O7 THERMAL BARRIER COATING CAUSED BY CALCIUM-MAGNESIUM-ALUMINUM-SILICON OXIDE (CMAS) DEPOSITION

    SciTech Connect

    Wang, Honglong; Sheng, Zhizhi; Tarwater, Emily; Zhang, Xingxing; Dasgupta, Sudip; Fergus, Jeffrey

    2015-03-16

    Rare earth zirconates are promising materials for use as thermal barrier coatings in gas turbine engines. Among the lanthanide zirconate materials, Sm2Zr2O7 with the pyrochlore structure has lower thermal conductivity and better corrosion resistance against calcium-magnesium-aluminum-silicon oxide (CMAS). In this work, after reaction with CMAS, the pyrochlore structure transforms to the cubic fluorite structure and Ca2Sm8(SiO4)6O2 forms in elongated grain.

  3. Chromium and yttrium-doped magnesium aluminum oxides prepared from layered double hydroxides

    NASA Astrophysics Data System (ADS)

    García-García, J. M.; Pérez-Bernal, M. E.; Ruano-Casero, R. J.; Rives, V.

    2007-12-01

    Layered double hydroxides with the hydrotalcite-like structures, containing Mg 2+ and Al 3+, doped with Cr 3+ and Y 3+, have been prepared by precipitation at constant pH. The weight percentages of Cr 3+ and Y 3+ were 1, 2, or 3%, and 0.5 or 1%, respectively. Single phases were obtained in all cases, whose crystallinity decreased as the content in Cr and Y was increased. The solids have been characterised by element chemical analysis, powder X-ray diffraction, thermal analyses (differential, thermogravimetric and programmed reduction), FT-IR and UV-vis spectroscopies; the specific surface areas have been determined from nitrogen adsorption isotherms at -196 °C. Upon calcination at 1200 °C for 5 h in air all solids display a mixed structure (spinel and rock salt for MgO); these solids have also been characterised by these techniques and their chromatic coordinates (CIE - L∗a∗b∗) have been determined. Their pink colour makes these solids suitable for being used as ceramic pigments.

  4. Influence of Aluminum Content on Grain Refinement and Strength of AZ31 Magnesium GTA Weld Metal

    SciTech Connect

    Babu, N. Kishore; Cross, Carl E.

    2012-06-28

    The goal is to characterize the effect of Al content on AZ31 weld metal, the grain size and strength, and examine role of Al on grain refinement. The approach is to systematically vary the aluminum content of AZ31 weld metal, Measure average grain size in weld metal, and Measure cross-weld tensile properties and hardness. Conclusions are that: (1) increased Al content in AZ31 weld metal results in grain refinement Reason: higher undercooling during solidification; (2) weld metal grain refinement resulted in increased strength & hardness Reason: grain boundary strengthening; and (3) weld metal strength can be raised to wrought base metal levels.

  5. Texture Control of Aluminum, Iron, and Magnesium Alloy Sheets to Increase Their Plastic Strain Ratios

    NASA Astrophysics Data System (ADS)

    Lee, Dong Nyung; Han, Heung Nam

    2011-08-01

    It is known that the limiting drawing ratio of sheet metals is proportional to their plastic strain ratios, and the plastic strain ratios of fcc and bcc metal sheets increase with increasing <111>//ND component in their textures. Conventional cold rolling and subsequent annealing of fcc metals cannot give rise to the <111>//ND component. Specifically, the cold rolling texture of polycrystalline fcc metals is characterized by the fiber connecting the {112}<111>, {123}<634>, and {011}<211> orientations in the Euler space, which is often called the β-fiber. The density of each component in the fiber depends on the stacking fault energy of metals. The {112}<111> and {123}<634> textured Al alloy sheets evolve the {001}<100> texture, when recrystallized. The low plastic strain ratios of the Al alloy sheets are attributed to the {001}<100> texture. The <111>//ND texture can be obtained in shear deformed fcc sheets. Bcc steels develop the <111>//ND texture when cold rolled and recrystallized. However, the density of <111>//ND depends on the content of dissolved interstitial elements such as carbon and nitrogen. The density of the <111>//ND component decreases with increasing concentration of the dissolved interstitial elements. For a given steel, the density of the <111>//ND component can vary with varying thermomechanical treatment. Magnesium alloy sheets are subjected to sheet forming processes at temperatures of 200 °C or higher because of their basal plane texture, or the <0002>//ND orientation. Many studies have been made to alleviate the component so that the magnesium alloy sheets can have better formability. In this article, the above issues are briefly reviewed and discussed.

  6. Effect of magnesium and silicon on the DIMOX processing of aluminum alloys

    SciTech Connect

    Yang, L.; Zhu, D.; Zhang, J.; Xu, C.Q.; Zhang, J.

    1995-08-01

    This paper deals with the reaction mechanisms of the DIMOX processing of aluminum alloys. Emphasis is placed on the distribution of Mg and Si in the products so that the behaviors of these two crucial elements for the oxidation aluminum could be revealed. Alterative methods, including optical and SEM microscopy, electron-probing and wave spectrum analysis were applied to specify the microstructure characters of the products and locate the position of both Mg and Si in the reaction products. It is shown that the products can be divided into four regions from where directly connected to the residual bulky metals to the surface area distinguished by microstructure. Both Mg and Si are rather concentrated in specific regions than homogeneously distributed in the whole products. The contents of Mg and Si in the surface region are not as high as expected with most of the Mg being concentrated in the region directly neighboring to the bulky metals and most of the Si in the residual bulky metals, although the contents of these two elements in the surface region are a little higher than the regions next to the surface. These characters, combined with other investigations, lead to the suggestion that circulated reactions could be a possible mechanism to explain the decisive role of the slight amount of Mg and Si in the nucleation and growth of Al{sub 2}O{sub 3}.

  7. Molecular interaction in alginate beads reinforced with sodium starch glycolate or magnesium aluminum silicate, and their physical characteristics.

    PubMed

    Puttipipatkhachorn, Satit; Pongjanyakul, Thaned; Priprem, Aroonsri

    2005-04-11

    Diclofenac calcium-alginate (DCA) beads were reinforced with different amounts of sodium starch glycolate (SSG) or magnesium aluminum silicate (MAS) and were prepared using ionotropic gelation method. Complex formation of sodium alginate (SA) and SSG or MAS in calcium-alginate beads was revealed using FTIR spectroscopy. Differential scanning calorimetric study indicated that diclofenac sodium (DS) in amorphous form was dispersed in the matrix of DCA beads. The thermal behavior of SSG-DCA and MAS-DCA beads was similar to the control bead. Both additives can improve the entrapment efficiency of DCA beads. The swelling and water uptake of the beads depended on the properties of incorporated additives. The SSG-DCA beads showed a higher water uptake and swelling than MAS-DCA beads. Moreover, the swelling of the beads showed a good correlation with the square root of time. The release kinetic of the beads in pH 6.8 phosphate buffer was swelling controlled mechanism, while that in distilled water followed Higuchi's model. The slower release rate and the longer lag time in pH 6.8 phosphate buffer was obtained from the SSG-DCA and MAS-DCA beads because of complex formation between SA and SSG or MAS. However, SSG in the beads could increase the release of DS from the beads in distilled water because it acted as a channeling agent. In contrast, MAS retarded the release of DS from the beads in distilled water due to the stronger matrix formation.

  8. The deformation and acoustic emission of aluminum-magnesium alloy under non-isothermal thermo-mechanical loading

    NASA Astrophysics Data System (ADS)

    Makarov, S. V.; Plotnikov, V. A.; Lysikov, M. V.; Kolubaev, E. A.

    2015-10-01

    The following study investigates the deformation behavior and acoustic emission in aluminum-magnesium alloy under conditions of non-isothermal thermo-mechanical loading. The accumulation of deformation in the alloy, in conditions of change from room temperature to 500°C, occurs in two temperature intervals (I, II), characterized by different rates of deformation. The rate of deformation accumulation is correlated with acoustic emission. With load increasing in cycles from 40 to 200 MPa, the value of the boundary temperature (Tb) between intervals I and II changes non-monotonically. In cycles with load up to 90 MPa, the Tb value increases, while an increase up to 200 MPa makes Tb shift toward lower temperatures. This suggests that the shift of boundaries in the region of low temperatures and the appearance of high-amplitude pulses of acoustic emission characterize the decrease of the magnitude of thermal fluctuations with increasing mechanical load, leading to the rupture of interatomic bonds in an elementary deformation act.

  9. The deformation and acoustic emission of aluminum-magnesium alloy under non-isothermal thermo-mechanical loading

    SciTech Connect

    Makarov, S. V.; Plotnikov, V. A. Lysikov, M. V.; Kolubaev, E. A.

    2015-10-27

    The following study investigates the deformation behavior and acoustic emission in aluminum-magnesium alloy under conditions of non-isothermal thermo-mechanical loading. The accumulation of deformation in the alloy, in conditions of change from room temperature to 500°C, occurs in two temperature intervals (I, II), characterized by different rates of deformation. The rate of deformation accumulation is correlated with acoustic emission. With load increasing in cycles from 40 to 200 MPa, the value of the boundary temperature (T{sub b}) between intervals I and II changes non-monotonically. In cycles with load up to 90 MPa, the T{sub b} value increases, while an increase up to 200 MPa makes T{sub b} shift toward lower temperatures. This suggests that the shift of boundaries in the region of low temperatures and the appearance of high-amplitude pulses of acoustic emission characterize the decrease of the magnitude of thermal fluctuations with increasing mechanical load, leading to the rupture of interatomic bonds in an elementary deformation act.

  10. Solidification, growth mechanisms, and associated properties of aluminum-silicon and magnesium lightweight casting alloys

    NASA Astrophysics Data System (ADS)

    Hosch, Timothy Al

    Continually rising energy prices have inspired increased interest in weight reduction in the automotive and aerospace industries, opening the door for the widespread use and development of lightweight structural materials. Chief among these materials are cast Al-Si and magnesium-based alloys. Utilization of Al-Si alloys depends on obtaining a modified fibrous microstructure in lieu of the intrinsic flake structure, a process which is incompletely understood. The local solidification conditions, mechanisms, and tensile properties associated with the flake to fiber growth mode transition in Al-Si eutectic alloys are investigated here using bridgman type gradient-zone directional solidification. Resulting microstructures are examined through quantitative image analysis of two-dimensional sections and observation of deep-etched sections showing three-dimensional microstructural features. The transition was found to occur in two stages: an initial stage dominated by in-plane plate breakup and rod formation within the plane of the plate, and a second stage where the onset of out-of-plane silicon rod growth leads to the formation of an irregular fibrous structure. Several microstructural parameters were investigated in an attempt to quantify this transition, and it was found that the particle aspect ratio is effective in objectively identifying the onset and completion velocity of the flake to fiber transition. The appearance of intricate out-of-plane silicon instability formations was investigated by adapting a perturbed-interface stability analysis to the Al-Si system. Measurements of silicon equilibrium shape particles provided an estimate of the anisotropy of the solid Si/liquid Al-Si system and incorporation of this silicon anisotropy into the model was found to improve prediction of the instability length scale. Magnesium alloys share many of the benefits of Al-Si alloys, with the added benefit of a 1/3 lower density and increased machinability. Magnesium castings

  11. Extraction processes for the production of aluminum, titanium, iron, magnesium, and oxygen and nonterrestrial sources

    NASA Technical Reports Server (NTRS)

    Rao, D. B.; Choudary, U. V.; Erstfeld, T. E.; Williams, R. J.; Chang, Y. A.

    1979-01-01

    The suitability of existing terrestrial extractive metallurgical processes for the production of Al, Ti, Fe, Mg, and O2 from nonterrestrial resources is examined from both thermodynamic and kinetic points of view. Carbochlorination of lunar anorthite concentrate in conjunction with Alcoa electrolysis process for Al; carbochlorination of lunar ilmenite concentrate followed by Ca reduction of TiO2; and subsequent reduction of Fe2O3 by H2 for Ti and Fe, respectively, are suggested. Silicothermic reduction of olivine concentrate was found to be attractive for the extraction of Mg becaue of the technological knowhow of the process. Aluminothermic reduction of olivine is the other possible alternative for the production of magnesium. The large quantities of carbon monoxide generated in the metal extraction processes can be used to recover carbon and oxygen by a combination of the following methods: (1) simple disproportionation of CO,(2) methanation of CO and electrolysis of H2O, and (3) solid-state electrolysis of gas mixtures containing CO, CO2, and H2O. The research needed for the adoption of earth-based extraction processes for lunar and asteroidal minerals is outlined.

  12. Hydrogen-environment-assisted cracking of an aluminum-zinc-magnesium(copper) alloy

    NASA Astrophysics Data System (ADS)

    Young, George Aloysius, Jr.

    There is strong evidence to indicate that hydrogen embrittlement plays a significant, if not controlling, role in the environmentally assisted cracking of 7XXX series aluminum alloys. In order to better understand hydrogen environment assisted cracking (HEAC), crack growth rate tests in the K-independent stage II crack growth regime were conducted on fracture mechanics specimens of an Al-6.09Zn-2.14Mg-2.19Cu alloy (AA 7050) and a low copper variant (Al-6.87Zn-2.65Mg-0.06Cu). Crack growth rate tests were performed in 90% relative humidity (RH) air between 25 and 90°C to assure hydrogen embrittlement control. The underaged, peak aged, and overaged tempers were investigated. Hydrogen uptake in humid air, hydrogen diffusion, and hydrogen trapping were investigated for each temper. Lastly, near crack tip hydrogen concentration depth profiles were analyzed via nuclear reaction analysis (NRA) and secondary ion mass spectroscopy (SIMS) using a liquid gallium, focused ion beam sputtering source (FIB/SIMS). The results of this study help explain and quantify empirically known trends concerning HEAC resistance and also establish new findings. In the copper bearing alloy, overaged tempers are more resistant but not immune to HEAC. Humid air is an aggressive environment for Al-Zn-Mg alloys because water vapor reacts with bare aluminum to produce high surface concentrations of hydrogen. This occurs in all tempers. Hydrogen diffuses from the near surface region to the high triaxial stress region ahead of the crack tip and collects at the high angle grain boundaries. The combination of tensile stress and high hydrogen concentration at the grain boundaries then causes intergranular fracture. Crack extension bares fresh metal and the process of hydrogen production, uptake, diffusion to the stressed grain boundary, and crack extension repeats. One reason increased degree of aging improves HEAC resistance in copper bearing 7XXX series alloys is that volume lattice and effective

  13. UV-visible transmission through nanohole arrays in aluminum and magnesium

    NASA Astrophysics Data System (ADS)

    Mao, Jieying; Wang, Yunshan; Appusamy, Kanagasundar; Guruswamy, Sivaraman; Blair, Steve

    2016-09-01

    Extraordinary optical transmission (EOT) is a classic phenomenon in plasmonics. The study of plasmonic nanostructures in the ultraviolet (UV) is a relatively uncharted field due to challenges in both engineering (nanostructure design, optimization, and fabrication) and materials science (detailed composition analysis). Our previous research has been mainly focused on UV field enhancement ofdifferent Al nanostructures. In this work, two-dimensional periodic nanohole arrays in Aluminium (Al) and Magnesium (Mg) films were fabricated using Ga focused ion beam (FIB) lithography. Optical transmission through the arrays was obtained in the UV and visible range, with varying array periodicity. Transmission results showed strong resonance enhancement in the UV and visible region resulting from SPP coupling, with corresponding red-shift as the period increases, while waveguide mode peaks remain in place. Comparing Al and Mg EOT results, Al hole-array enabled larger transmission than that of Mg. Dips in transmission through Al arrays occur at similar spectral positions to those of Mg arrays with same periods. Numerical analysis was carried out through finite-difference-time-domain (FDTD) method, which showed far-field transmission consistent with experiments in general. The model was constructed based on transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS) of cross-sectioned samples. The effect of Gallium (Ga) implantation from FIB fabrication was qualitatively studied, which indicated Ga implants inside the hole bottom as well as higher implantation within Mg than that within Al. The model also takes into account sidewall geometry and undercut into the substrate.

  14. On the benefit of magnetic magnesium nanocarrier in cardiovascular toxicity of aluminum phosphide.

    PubMed

    Baeeri, Maryam; Shariatpanahi, Marjan; Baghaei, Amir; Ghasemi-Niri, Seyedeh Farnaz; Mohammadi, Hamidreza; Mohammadirad, Azadeh; Hassani, Shokoufeh; Bayrami, Zahra; Hosseini, Asieh; Rezayat, Seyed Mahdi; Abdollahi, Mohammad

    2013-03-01

    The present study was designed to determine the effect of a new (25)Mg(2+)-carrying nanoparticle ((25)MgPMC16) on energy depletion, oxidative stress, and electrocardiographic (ECG) parameters on heart tissue of the rats poisoned by aluminum phosphide (AlP). (25)MgPMC16 at doses of 0.025, 0.05, and 0.1 median lethal dose (LD50 = 896 mg/kg) was administered intravenously (iv) 30 min after a single intragastric administration of AlP (0.25 LD50). Sodium bicarbonate (Bicarb; 2 mEq/kg, iv) was used as the standard therapy. After anesthesia, the animals were rapidly connected to an electronic cardiovascular monitoring device for monitoring of ECG, blood pressure (BP), and heart rate (HR). Later lipid peroxidation, antioxidant power, ATP/ADP ratio, and Mg concentration in the heart were evaluated. Results indicated that after AlP administration, BP and HR decreased while R-R duration increased. (25)MgPMC16 significantly increased the BP and HR at all doses used. We found a considerable increase in antioxidant power, Mg level in the plasma and the heart and a reduction in lipid peroxidation and ADP/ATP ratio at various doses of (25)MgPMC16, but (25)MgPMC16-0.025 + Bicarb was the most effective combination therapy. The results of this study support that (25)MgPMC16 can increase heart energy by active transport of Mg inside the cardiac cells.(25)MgPMC16 seems ameliorating AlP-induced toxicity and cardiac failure necessitating further studies.

  15. Interstitial-impurity interactions in copper-silver and aluminum-magnesium alloys. [Electron beams

    SciTech Connect

    Wong, H.P.

    1982-01-01

    The configurations and dynamical properties of complexes formed between interstitials and oversized impurities in electron-irradiated aluminum and copper were determined. Measurements were taken of the ultrasonic attention and resonant frequency in single crystal samples of Cu-Ag and Al-Mg. A variety of peaks appeared in both materials in plots of the logarithmic decrement versus temperature. The simultaneous presence of multiple defects was established by the different annealing behavior shown by each peak. It was found that interstitial trapping in our oversized systems was generally weaker than in previously studied undersized systems. The principal features in Cu-Ag that must be accounted for by a model include the following: (1) Three low-temperature peaks were seen having trigonal symmetry. The main peak annealed away at 110 K uncorrelated with any resistivity recovery and it grew at 60 K, correlated with a resistivity decrease. For Al-MG, the principal features associated with the main peak include: seen at high temperature (>135 K) having trigonal symmetry; annealed away at 127 K and seemed to correlate with a resistivity decrease; remaining peaks grew while the main peak annealed away. The implications of an existing model were developed. No evidence was found for the deeply-trapped <110>-orthorhombic defect predicted by the existing model. Therefore, two alternative models were developed. Model A uses a canted dumb-bell at the next-nearest neighbor position to explain the results. Model B uses a point interstitial at an octahedral position. A distinction between the two which is subject to experimental check is that model A predicts that interstitial migration between different impurity atoms occurs near 127 K in Cu-Ag while model B predicts a migration temperature near 60 K.

  16. Effect of magnesium content on the semi solid cast microstructure of hypereutectic aluminum-silicon alloys

    NASA Astrophysics Data System (ADS)

    Hekmat-Ardakan, Alireza

    2009-12-01

    A comprehensive study of microstructural evolution of A390 hypereutectic aluminum-silicon alloy (Al-17%Si-4.5%Cu-0.5%Mg) with addition of Mg contents up to 10% was carried out during semi solid metal processing as well as conventional casting. As a first step, the FACTSAGE thermodynamic databank and software was applied in order to investigate the phase diagram, the solidification behavior as well as the identification of the components that are formed during the solidification of A390 alloy with different Mg contents for equilibrium and non-equilibrium (Schiel) conditions. With higher Mg content between 4.2 - 7.2 %, the Mg2Si intermetallic phase is solidified in the eutectic network according to the ternary reaction together the primary silicon due to the binary reaction of Liq → Si + Mg2Si. However the primary silicon is still the first solidified phase in this critical Mg zone. For Mg contents greater than 7.2%, the Mg2Si solidifies first as a primary phase. In fact, the Mg2Si is solidified during the primary, the binary and the ternary reactions and can be observed in the microstructure as a eutectic phase and a pro-eutectic phase with different morphology. In the next stage, the experimental tests were carried out in order to verify the accuracy of the results obtained by the FACTSAGE software. The microstructures of the A390 and the 6 and 10 wt% Mg alloys were investigated using conventional casting and rheocasting (stir casting) processes with continuous cooling solidification. The results showed that, for both processes, the microstructure of the eutectic network for high Mg alloys, specifically the eutectic Si phase is modified compared to the eutectic Si in the microstructure of A390 alloy. However the alloys with 6% and 10% Mg have a similar eutectic morphology. The eutectic formation temperature was measured by placing the thermocouple into the melt for determination of the cooling curves. DSC (Differential Scanning Calorimeter) test were also carried

  17. Effect of geometrical stress concentrators on the current-induced suppression of the serrated deformation in an aluminum-magnesium AlMg5 alloy

    NASA Astrophysics Data System (ADS)

    Shibkov, A. A.; Zolotov, A. E.; Zheltov, M. A.; Denisov, A. A.; Gasanov, M. F.; Kochegarov, S. S.

    2016-05-01

    The effect of an electric current on the band formation and the serrated deformation of planar specimens made of an aluminum-magnesium AlMg5 alloy and weakened by holes is experimentally studied. It is found that the concentration of elastic stress fields and the self-localized unstable plastic deformation field near a hole decreases the critical strain of appearance of the first stress drop and hinders the currentinduced suppression of band formation and the serrated Portevin-Le Chatelier deformation. These results are shown not to be related to the concentration of Joule heat near a hole.

  18. Preparation and controlled-release studies of a protocatechuic acid-magnesium/aluminum-layered double hydroxide nanocomposite

    PubMed Central

    Barahuie, Farahnaz; Hussein, Mohd Zobir; Hussein-Al-Ali, Samer Hasan; Arulselvan, Palanisamy; Fakurazi, Sharida; Zainal, Zulkarnain

    2013-01-01

    In the study reported here, magnesium/aluminum (Mg/Al)-layered double hydroxide (LDH) was intercalated with an anticancer drug, protocatechuic acid, using ion-exchange and direct coprecipitation methods, with the resultant products labeled according to the method used to produce them: “PANE” (ie, protocatechuic acid-Mg/Al nanocomposite synthesized using the ion-exchange method) and “PAND” (ie, protocatechuic acid-Mg/Al nanocomposite synthesized using the direct method), respectively. Powder X-ray diffraction and Fourier transform infrared spectroscopy confirmed the intercalation of protocatechuic acid into the inter-galleries of Mg/Al-LDH. The protocatechuic acid between the interlayers of PANE and PAND was found to be a monolayer, with an angle from the z-axis of 8° for PANE and 15° for PAND. Thermogravimetric and differential thermogravimetric analysis results revealed that the thermal stability of protocatechuic acid was markedly enhanced upon intercalation. The loading of protocatechuic acid in PANE and PAND was estimated to be about 24.5% and 27.5% (w/w), respectively. The in vitro release study of protocatechuic acid from PANE and PAND in phosphate-buffered saline at pH 7.4, 5.3, and 4.8 revealed that the nanocomposites had a sustained release property. After 72 hours incubation of PANE and PAND with MCF-7 human breast cancer and HeLa human cervical cancer cell lines, it was found that the nanocomposites had suppressed the growth of these cancer cells, with a half maximal inhibitory concentration of 35.6 μg/mL for PANE and 36.0 μg/mL for PAND for MCF-7 cells, and 19.8 μg/mL for PANE and 30.3 μg/mL for PAND for HeLa cells. No half maximal inhibitory concentration for either nanocomposite was found for 3T3 cells. PMID:23737666

  19. Energy-Saving Melting and Revert Reduction Technology (E-SMARRT): Lost Foam Thin Wall - Feasibility of Producing Lost Foam Castings in Aluminum and Magnesium Based Alloys

    SciTech Connect

    Fasoyinu, Yemi; Griffin, John A.

    2014-03-31

    With the increased emphasis on vehicle weight reduction, production of near-net shape components by lost foam casting will make significant inroad into the next-generation of engineering component designs. The lost foam casting process is a cost effective method for producing complex castings using an expandable polystyrene pattern and un-bonded sand. The use of un-bonded molding media in the lost foam process will impose less constraint on the solidifying casting, making hot tearing less prevalent. This is especially true in Al-Mg and Al-Cu alloy systems that are prone to hot tearing when poured in rigid molds partially due to their long freezing range. Some of the unique advantages of using the lost foam casting process are closer dimensional tolerance, higher casting yield, and the elimination of sand cores and binders. Most of the aluminum alloys poured using the lost foam process are based on the Al-Si system. Very limited research work has been performed with Al-Mg and Al-Cu type alloys. With the increased emphasis on vehicle weight reduction, and given the high-strength-to-weight-ratio of magnesium, significant weight savings can be achieved by casting thin-wall (≤ 3 mm) engineering components from both aluminum- and magnesium-base alloys.

  20. Spark Plasma Sintering of Aluminum-Magnesium-Matrix Composites with Boron Carbide and Tungsten Nano-powder Inclusions: Modeling and Experimentation

    NASA Astrophysics Data System (ADS)

    Dvilis, E. S.; Khasanov, O. L.; Gulbin, V. N.; Petyukevich, M. S.; Khasanov, A. O.; Olevsky, E. A.

    2016-03-01

    Spark-plasma sintering (SPS) is used to fabricate fully-dense metal-matrix (Al/Mg) composites containing hard ceramic (boron carbide) and refractory metal (tungsten) inclusions. The study objectives include the modeling (and its experimental verification) of the process of the consolidation of the composites consisted of aluminum-magnesium alloy AMg6 (65 wt.%), B4C powder (15 wt.%), and W nano-powder (20 wt.%), as well as the optimization of the composite content and of the SPS conditions to achieve higher density. Discrete element modeling of the composite particles packing based on the particle size distribution functions of real powders is utilized for the determination of the powder compositions rendering maximum mixture packing densities. Two models: a power-law creep model of the high temperature deformation of powder materials, and an empirical logarithmic pressure-temperature-relative density relationship are successfully applied for the description of the densification of the aluminum-magnesium metal matrix powder composite subjected to spark-plasma sintering. The elastoplastic properties of the sintered composite samples are assessed by nanoindentation.

  1. Chromian spinels from Apollo 14 rocks.

    NASA Technical Reports Server (NTRS)

    Steele, I. M.

    1972-01-01

    Results of electron microprobe analysis of 13 pink, isotropic, high-relief grains from Apollo 14 elastic rock 14063,14 and a lithic fragment from the 1 to 2 mm fines, 14002,7, identifying them as spinel minerals dominated by the spinel component MgAl2O4 associated with a moderate content of chromite and hercynite. The spinel is thought to have crystallized from a magma high in aluminum and low in iron, with possible crystal separation, followed by incorporation in clastic rocks by impacts. Many bulk compositions of the elastic fragments fall near the field of primary spinel in the model system An-Fo-SiO2. Experimental syntheses of Apollo 14 rocks are needed to test the suggested primary origin.

  2. Calcium-aluminum-rich inclusions with fractionation and unidentified nuclear effects (FUN CAIs): II. Heterogeneities of magnesium isotopes and 26Al in the early Solar System inferred from in situ high-precision magnesium-isotope measurements

    NASA Astrophysics Data System (ADS)

    Park, Changkun; Nagashima, Kazuhide; Krot, Alexander N.; Huss, Gary R.; Davis, Andrew M.; Bizzarro, Martin

    2017-03-01

    Calcium-aluminum-rich inclusions with isotopic mass fractionation effects and unidentified nuclear isotopic anomalies (FUN CAIs) have been studied for more than 40 years, but their origins remain enigmatic. Here we report in situ high precision measurements of aluminum-magnesium isotope systematics of FUN CAIs by secondary ion mass spectrometry (SIMS). Individual minerals were analyzed in six FUN CAIs from the oxidized CV3 carbonaceous chondrites Axtell (compact Type A CAI Axtell 2271) and Allende (Type B CAIs C1 and EK1-4-1, and forsterite-bearing Type B CAIs BG82DH8, CG-14, and TE). Most of these CAIs show evidence for excess 26Mg due to the decay of 26Al. The inferred initial 26Al/27Al ratios [(26Al/27Al)0] and the initial magnesium isotopic compositions (δ26Mg0) calculated using an exponential law with an exponent β of 0.5128 are (3.1 ± 1.6) × 10-6 and 0.60 ± 0.10‰ (Axtell 2271), (3.7 ± 1.5) × 10-6 and -0.20 ± 0.05‰ (BG82DH8), (2.2 ± 1.1) × 10-6 and -0.18 ± 0.05‰ (C1), (2.3 ± 2.4) × 10-5 and -2.23 ± 0.37‰ (EK1-4-1), (1.5 ± 1.1) × 10-5 and -0.42 ± 0.08‰ (CG-14), and (5.3 ± 0.9) × 10-5 and -0.05 ± 0.08‰ (TE) with 2σ uncertainties. We infer that FUN CAIs recorded heterogeneities of magnesium isotopes and 26Al in the CAI-forming region(s). Comparison of 26Al-26Mg systematics, stable isotope (oxygen, magnesium, calcium, and titanium) and trace element studies of FUN and non-FUN igneous CAIs indicates that there is a continuum among these CAI types. Based on these observations and evaporation experiments on CAI-like melts, we propose a generic scenario for the origin of igneous (FUN and non-FUN) CAIs: (i) condensation of isotopically normal solids in an 16O-rich gas of approximately solar composition; (ii) formation of CAI precursors by aggregation of these solids together with variable abundances of isotopically anomalous grains-possible carriers of unidentified nuclear (UN) effects; and (iii) melt evaporation of these precursors

  3. The Ballistic and Corrosion Evaluation of Magnesium Elektron E675 vs. Baseline Magnesium Alloy AZ31B and Aluminum Alloy 5083 for Armor Applications

    DTIC Science & Technology

    2011-06-01

    Titanium — — 0.15 max Others each 0.05 max — 0.05 max Others total — 0.30 max 0.15 max Magnesium 99.80 min REM 4.0–4.9 max Specification cited ASTM...W COOK EGLIN AFB FL 32542 4 UNIV OF TEXAS INST FOR ADVNCD TECH S BLESS H FAIR J HODGE R SUBRAMANIAN 3925 W BRAKER LN...RSRCH INST T HOLMQUIST G JOHNSON 5353 WAYZATA BLVD STE 607 MINNEAPOLIS MN 55416 1 US ARMY RAPID EQUIPPING FORCE R TURNER 10236

  4. Removal of tetrafluoroborate ion from aqueous solution using magnesium-aluminum oxide produced by the thermal decomposition of a hydrotalcite-like compound.

    PubMed

    Yoshioka, Toshiaki; Kameda, Tomohito; Miyahara, Motoya; Uchida, Miho; Mizoguchi, Tadaaki; Okuwaki, Akitsugu

    2007-10-01

    Magnesium-aluminum oxide (Mg-Al oxide) prepared by the thermal decomposition of a hydrotalcite-like compound was found to have potential for treating NaBF(4) wastewater. The Mg-Al oxide removed the BF(4)(-) and F(-) and H(3)BO(3) from the NaBF(4) solution. With increasing Mg-Al oxide quantity and time, the BF(4)(-) concentration decreased and the degree of BF(4)(-), F(-), and boron removal increased. The decrease in the BF(4)(-) concentration resulted from uptake by the Mg-Al oxide and not hydrolysis. The Mg-Al oxide took up F(-) from the solution preferentially. The Mg-Al oxide also converted the H(3)BO(3) in the aqueous solution into H(2)BO(3)(-), which it took up.

  5. Double-blind clinical, endoscopic and histological comparison of hydrotalcite/dimethicone suspension and magnesium hydroxide/aluminum hydroxide suspension in the treatment of symptomatic gastritis.

    PubMed

    Cobden, I; McMahon, M J; Dixon, M F; Axon, A T

    1981-01-01

    A double-blind, randomized trial was undertaken to compare the clinical, endoscopic and histological response to 6-weeks' treatment with hydrotalcite/dimethicone suspension or magnesium hydroxide/aluminum hydroxide suspension in 36 patients with symptomatic gastritis. Significantly more patients (P less than 0.05) showed symptomatic improvement in the antacid-treated group than in the hydrotalcite/dimethicone-treated group and more had a reduction in histological inflammatory scores (P less than 0.01), although there was little correlation between histology and symptoms. There was no evidence from this study that the bile acid binding and anti-foaming properties of hydrotalcite/dimethicone suspension were of any benefit in the treatment of patients with symptomatic gastritis.

  6. Low-pH and aluminum resistance in arabidopsis correlates with high cytosolic magnesium content and increased magnesium uptake by plant roots.

    PubMed

    Bose, Jayakumar; Babourina, Olga; Shabala, Sergey; Rengel, Zed

    2013-07-01

    Low-pH stress and Al(3+) toxicity affect root growth in acid soils. It was hypothesized that the capacity of genotypes to maintain Mg(2+) uptake in acidic environments may contribute to low-pH and Al resistance, but explicit evidence is lacking. In this work, an Al-resistant alr104 mutant and two Al-sensitive mutants (als5 and als3) of Arabidopsis thaliana were compared with the wild type (Col-0) for Mg(2+) uptake and intracellular Mg(2+) concentration under low-pH and combined low-pH/Al stresses. Magnesium accumulation in roots was measured in long-term (7 d) experiments. The Mg(2+) fluxes were measured using ion-sensitive microelectrodes at the distal elongation and the mature root zones in short-term (0-60 min) experiments. Intracellular Mg(2+) concentrations were measured in intact root cells at the distal elongation zone using magnesium-specific fluorescent dye and fluorescent lifetime imaging (FLIM) analysis. Under low-pH stress, Arabidopsis mutants als5 and alr104 maintained a higher Mg concentration in roots, and had greater Mg(2+) influx than the wild type and the als3 mutant. Under combined low-pH/Al treatment, Al-resistant genotypes (wild type and alr104) maintained a higher Mg(2+) accumulation, and had a higher Mg(2+) influx and higher intracellular Mg(2+) concentration than Al-sensitive genotypes (als3 and als5). Overall, these results show that increased Mg(2+) uptake correlates with an enhanced capacity of Arabidopsis genotypes to cope with low-pH and combined low-pH/Al stresses.

  7. Analysis of the Fragmentation of AlON and Spinel Under Ballistic Impact

    DTIC Science & Technology

    2013-05-01

    aluminate spinel (MgAl2O4) and AlON are promis- ing candidate materials for application as a hard front layer in transparent armor. Com- prehensive...sized spinel and AlON was observed. [DOI: 10.1115/1.4023573] Keywords: fragmentation, ceramic, AlON, magnesium aluminate spinel, high-speed...investigated the failure of glass due to the penetration of steel projectiles of size and shape similar to the steel cores of armor-piercing

  8. The crystallisation trends of spinels in tertiary basalts from Rhum and Muck and their petrogenetic significance. [chemical composition changes during crystal formation

    NASA Technical Reports Server (NTRS)

    Ridley, W. I.

    1977-01-01

    Spinels found in transitional olivine basalts from the Islands of Rhum and Muck in the British Tertiary Province are analyzed to determine their chemical variability and their relationship to silicate phases. Chemical zoning of the cores of spinels which spilled into the basaltic liquid may be due to a reaction between the spinel and the liquid resulting in more Fe- and Ti-rich spinels. In addition, a peritectic-type reaction seems to have occurred, causing the transformation of aluminum spinel to chrome spinel with precipitation of plagioclase. Changes in the basaltic liquid are reflected by these transformations in the spinel composition.

  9. Physicochemical properties of magnesium aluminum silicate (smectone) gels prepared using electrolytic-reduction ion water (2): Effects of various salts on the phase diagram.

    PubMed

    Okajima, Masahiro; Shimokawa, Ken-ichi; Ishii, Fumiyoshi

    2009-09-01

    We produced gels using electrolytic-reduction ion water and magnesium aluminum silicates (smectone), and evaluated in detail gel properties in the presence of various types of salt (NaCl, KCl, CaCl(2), MgCl(2), and AlCl(3)). Each salt was added to deionized-distilled water or electrolytic-reduction ion water, and phase diagrams for the smectone concentration (2.0-4.0%) were produced. The areas of the three phases of smectone (gel, sol, and separation) at each salt concentration were expressed as percentages of the total area. As a result, uni- and polyvalent cations (excluding Ca(2+) ions) affected the stability of gels produced using electrolytic-reduction ion water, and, particularly, univalent cations (Na(+), K(+)) markedly improved gel stability. Using electrolytic-reduction ion water as a dispersal medium, drug delivery systems (DDS) that can maintain the gelling state can be prepared. Thus, gel preparations with maintained functions or controlled-release transdermal drugs can be obtained.

  10. Modeling the Break-up of Nano-particle Clusters in Aluminum- and Magnesium-Based Metal Matrix Nano-composites

    NASA Astrophysics Data System (ADS)

    Manoylov, Anton; Bojarevics, Valdis; Pericleous, Koulis

    2015-07-01

    Aluminum- and magnesium-based metal matrix nano-composites with ceramic nano-reinforcements promise low weight with high durability and superior strength, desirable properties in aerospace, automobile, and other applications. However, nano-particle agglomerations lead to adverse effects on final properties: large-size clusters no longer act as dislocation anchors, but instead become defects; the resulting particle distribution will be uneven, leading to inconsistent properties. To prevent agglomeration and to break-up clusters, ultrasonic processing is used via an immersed sonotrode, or alternatively via electromagnetic vibration. A study of the interaction forces holding the nano-particles together shows that the choice of adhesion model significantly affects estimates of break-up force and that simple Stokes drag due to stirring is insufficient to break-up the clusters. The complex interaction of flow and co-joint particles under a high frequency external field (ultrasonic, electromagnetic) is addressed in detail using a discrete-element method code to demonstrate the effect of these fields on de-agglomeration.

  11. Salicylic acid alleviates aluminum toxicity in rice seedlings better than magnesium and calcium by reducing aluminum uptake, suppressing oxidative damage and increasing antioxidative defense.

    PubMed

    Pandey, Poonam; Srivastava, Rajneesh Kumar; Dubey, R S

    2013-05-01

    Aluminum toxicity is a major constraint to crop production in acid soils. The present study was undertaken to examine the comparative ameliorating effects of salicylic acid, Ca and Mg on Al toxicity in rice (Oryza sativa L.) seedlings grown in hydroponics. Al treatment (0.5 mM AlCl3) caused decrease in plant vigour, loss of root plasma membrane integrity, increased contents of O 2 (∙-) , H2O2, lipid peroxidation, protein carbonyls and decline in the level of protein thiol. Al treatment caused significant changes in activity of antioxidative enzymes in rice seedlings. Exogenously added salicylic acid (60 μM), Ca (1 mM) and Mg (0.25 mM) significantly alleviated Al toxicity effects in the seedlings marked by restoration of growth, suppression of Al uptake, restoration of root plasma membrane integrity and decline in O 2 (∙-) , H2O2, lipid peroxidation and protein carbonyl contents. Salicylic acid, Ca and Mg suppressed Al-induced increase in SOD, GPX and APX activities while it elevated Al-induced decline in CAT activity. By histochemical staining of O 2 (∙-) using NBT and H2O2 using DAB, it was further confirmed that added salicylic acid, Ca or Mg decreased Al-induced accumulation of O 2 (∙-) and H2O2 in the leaf tissues. Results indicate that exogenously added salicylic acid, Ca or Mg alleviates Al toxicity in rice seedlings by suppressing Al uptake, restoring root membrane integrity, reducing ROS level and ROS induced oxidative damage and regulating the level of antioxidative enzyme activities. Further salicylic appears to be superior to Mg and Ca in alleviating Al toxicity effects in rice plants.

  12. Luna 24 - Systematics in spinel mineral chemistry in the context of an intrusive petrogenetic grid

    NASA Technical Reports Server (NTRS)

    Haggerty, S. E.

    1978-01-01

    Spinels in the Luna 24 gabbroic fragments have a restricted bimodal distribution of aluminum chromite and ulvospinel, whereas those in the Luna 24 basalts form a continuous sequence which defines a compositional variation from Al-Mg-chromites to ulvospinels containing 1 wt% Al2O3. A comparison of these spinel mineral chemistries with basaltic spinels from other mare regions and with spinels from other lunar intrusive rocks suggest that the Luna 24 gabbroic spinels lie at the low pressure end of a P-T spinel grid, and that titanium enrichment trends on Mg-Al-Cr rich spinel cores are related to extrusion and formed at the terminal stages of magmatic crystallization.

  13. Reversible Coordination of Boron-, Aluminum-, Zinc-, Magnesium-, and Calcium-Hydrogen Bonds to Bent {CuL2} Fragments: Heavy σ Complexes of the Lightest Coinage Metal.

    PubMed

    Hicken, Alexandra; White, Andrew J P; Crimmin, Mark R

    2017-03-22

    A series of copper(I) complexes bearing electron-deficient β-diketiminate ligands have been prepared. The study includes [{{ArNC(CR3)}2CH}Cu(η(2)-toluene)n] (Ar = Mes, R = F, n = 0.5, [12·tol]; Ar = C6F5, R = Me, n = 1, [2·tol]; Ar = 2,6-Cl2C6H3, R = H, n = 0.5, [32·tol]). Reactions of [1-3n·tol] with boranes, alanes, a zinc hydride, a magnesium hydride, and a calcium hydride generate the corresponding σ complexes ([1-3·B], [3·B'], [3·Al], [3·Al'], [1-3·Zn], [1·Mg], and [1·Ca]). These species all form reversibly, being in equilibrium with the arene solvates in solution. With the exception of the calcium complex, the complexes have all been characterized by single-crystal X-ray diffraction studies. In solution, the σ-hydride of the aluminum, zinc, magnesium, and calcium derivatives resonates between -0.12 and -1.77 ppm (C6D6 or toluene-d8, 193-298 K). For the σ-borane complexes, the hydrides are observed as a single resonance between 2 and 3.5 ppm (C6D6, 298 K) and bridging and terminal hydrides rapidly exchange on the NMR time scale even at 193 K. Quantification of the solution dynamics by van't Hoff analysis yields expectedly small values of ΔH° and negative values of ΔS° consistent with weak binding and a reversible process that does not involve aggregation of the copper species. The donor-acceptor complexes can be rationalized in terms of the Dewar-Chatt-Duncanson model. Density functional theory calculations show that the donation of σ-M-H (or E-H) electrons into the 4s-based orbital (LUMO or LUMO+1) of the copper fragment is accompanied by weak back-donation from a dxz-based orbital (HOMO or HOMO-1) into the σ*-M-H (or E-H) orbital.

  14. Temperature dependent phase transformation in nano sized magnesium ferrite

    NASA Astrophysics Data System (ADS)

    Sumangala T., P.; Mahender, C.; Venkataramani, N.; Prasad, Shiva

    2015-06-01

    The phase transformation in nanosized stoichiometric magnesium ferrite is being discussed. It was shown by TGA/DSC that there exist two reactions (shown by exothermic peaks) in nano sized magnesium ferrite when synthesized by sol gel combustion synthesis. First one of these reactions resulted in the precipitation of α-Fe2O3 and a resultant spinel. The second reaction resulted in stoichiometric spinel from this two phase system.

  15. Slow crack growth in spinel in water

    NASA Technical Reports Server (NTRS)

    Schwantes, S.; Elber, W.

    1983-01-01

    Magnesium aluminate spinel was tested in a water environment at room temperature to establish its slow crack-growth behavior. Ring specimens with artificial flaws on the outside surface were loaded hydraulically on the inside surface. The time to failure was measured. Various precracking techniques were evaluated and multiple precracks were used to minimize the scatter in the static fatigue tests. Statistical analysis techniques were developed to determine the strength and crack velocities for a single flaw. Slow crack-growth rupture was observed at stress intensities as low as 70 percent of K sub c. A strengthening effect was observed in specimens that had survived long-time static fatigue tests.

  16. S-asteroids 387 Aquitania and 980 Anacostia - Possible fragments of the breakup of a spinel-bearing parent body with CO3/CV3 affinities

    NASA Technical Reports Server (NTRS)

    Burbine, Thomas H.; Gaffey, Michael J.; Bell, Jeffrey F.

    1992-01-01

    Asteroids 387 Aquitania and 980 Anacostia are anomalous members of the S-class. Their reflectance spectra exhibit a strong broad absorption feature longwards of 1.5 micron and no significant feature near 1 micron. Their spectra indicate the presence of spinel, an aluminum-magnesium oxide mineral commonly present in inclusions in CV3 and CO3 meteorites. Spinel probably makes up only a small percentage of the surface assemblages of these asteroids, but its spectral effect may be enhanced by its presence in fine-grained white inclusions in immature asteroid regoliths. It is speculated that Aquitania and Anacostia represent material formed in the same nebular zone as the CV3 and CO3 chondrites but either: (A) at an earlier time in the nebula when such inclusions might have been a relatively larger fraction of the nebular grain population; or (B) in local regions where nebular processes (e.g., settling to the midplane) had concentrated such inclusions. The close similarity of two orbital elements (a, i) suggests that Aquitania and Anacostia may be members of a partially dispersed asteroid family produced by the early disruption of a spinel-bearing parent body.

  17. Thermoelectric Properties of Selenides Spinels

    NASA Technical Reports Server (NTRS)

    Snyder, G.; Caillat, T.; Fleurial, J-P.

    2000-01-01

    Many compounds with the spinel structure type have been analyzed for their thermoelectric properties. Published data was used to augment experimental results presented here to select promising thermoelectric spinels.

  18. Fabrication of large thick panels of transparent spinel

    NASA Astrophysics Data System (ADS)

    Patterson, Mark; Gilde, Gary A.; Roy, Donald W.

    2001-11-01

    The use of magnesium aluminate spinel for optical windows, domes and armor has previously been investigated for a wide range of specific applications. The material properties rival that of ALON and sapphire, although there exists the potential for the fabrication of larger parts at significantly lower costs. The ability to fabricate transparent spinel by hot-pressing into large plates has gained interest for the fabrication of low-cost transparent armor for a range of applications. The present paper describes development efforts that are underway to fabricate spinel panels up to 22 inches in diameter and 0.5 inches thick. A 600 ton press is being installed at a facility in Millersville, MD that will be able to fabricate 22 inch diameter parts by late 2002. In the future, this press will potentially be able to fabricate 40 inch diameter plates with minimal changes. There is additional interest in these plates for large IR windows.

  19. Surface stability of spinel MgNi0.5Mn1.5O4 and MgMn2O4 as cathode materials for magnesium ion batteries

    NASA Astrophysics Data System (ADS)

    Jin, Wei; Yin, Guangqiang; Wang, Zhiguo; Fu, Y. Q.

    2016-11-01

    Rechargeable ion batteries based on the intercalation of multivalent ions are attractive due to their high energy density and structural stability. Surface of cathode materials plays an important role for the electrochemical performance of the rechargeable ion batteries. In this work we calculated surface energies of (001), (110) and (111) facets with different terminations in spinel MgMn2O4 and MgNi0.5Mn1.5O4 cathodes. Results showed clearly that atomic reconstruction occurred due to surface relaxation. The surface energies for the (001), (110) and (111) surfaces of the MgNi0.5Mn1.5O4 were 0.08, 0.13 and 0.11 J/m2, respectively, whereas those of the Ni-doped MgMn2O4 showed less dependence on the surface structures.

  20. ALUMINUM IMPURITY DIFFUSION IN MAGNESIUM

    SciTech Connect

    Brennan, Sarah; Warren, Andrew; Coffey, Kevin; Kulkarni, Nagraj S; Todd, Peter J; Sohn, Yong Ho; Klimov, Mikhail

    2012-01-01

    The Al impurity diffusion in polycrystalline Mg (99.9%) via depth profiling with secondary ion mass spectrometry was studied in the temperature range of 673-573K, utilizing the thin film method and thin film solution to the diffusion equation. Multiple samples were utilized and multiple profiles were obtained to determine statistically confident coefficient with maximum standard deviation of 16%. Activation energy and pre-exponential factor of Al impurity diffusion in Mg was determined as 155 kJ/mole and 3.9 x 10-3 m2/sec.

  1. Aluminum Hydroxide and Magnesium Hydroxide

    MedlinePlus

    ... Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website (http://goo.gl/c4Rm4p) for ...

  2. Magnesium basics

    PubMed Central

    Ketteler, Markus

    2012-01-01

    As a cofactor in numerous enzymatic reactions, magnesium fulfils various intracellular physiological functions. Thus, imbalance in magnesium status—primarily hypomagnesaemia as it is seen more often than hypermagnesaemia—might result in unwanted neuromuscular, cardiac or nervous disorders. Measuring total serum magnesium is a feasible and affordable way to monitor changes in magnesium status, although it does not necessarily reflect total body magnesium content. The following review focuses on the natural occurrence of magnesium and its physiological function. The absorption and excretion of magnesium as well as hypo- and hypermagnesaemia will be addressed. PMID:26069819

  3. Compositional variations in lunar spinels.

    NASA Technical Reports Server (NTRS)

    Haggerty, S. E.

    1971-01-01

    Electron probe data for spinels from Apollo 11, 12, and 14 are presented and analyzed. A modified Johnstone spinel prism showing the data distribution is given. Three projections of this prism are then presented which illustrate the variations of simple ratios that are present in the prism and permit three different perspectives of the data. The results are summarized as fO2 isobars on the spinel prism.

  4. Magnesium Repair by Cold Spray

    DTIC Science & Technology

    2008-05-01

    were conducted using microstructural analysis, hardness, bond strength, and corrosion testing. 15. SUBJECT TERMS Cold spray, magnesium, aluminum ... corrosion pitting are the primary causes for removing the components from service. In addition, any repair must be confined to nonstructural areas of...unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT The U.S. Army has experienced significant corrosion problems with magnesium alloys that are used to

  5. Nanohardness and brittleness of irradiated spinel ceramics

    NASA Astrophysics Data System (ADS)

    Jagielski, J.; Aubert, P.; Maciejak, O.; Piatkowska, A.; Labdi, S.; Jozwik-Biala, I.; Jozwik, P.; Wajler, A.

    2012-09-01

    The influence of the size of crystalline regions on mechanical properties of irradiated oxides has been studied using magnesium aluminate spinel MgAl2O4. The samples characterized by different dimensions of crystalline domains, from sintered ceramics with grains of few micrometers in size up to single crystals, were used in the experiments. The samples were irradiated at room temperature with 320 keV Ar2+ ions up to fluences reaching 5 × 1016 cm-2. Nanomechanical properties were measured by using a nanoindentation technique and the resistance to crack formation by measurement of the total crack lengths made by Vickers indenter. The results revealed: correlation of nanohardness with accumulated damage, radiation-induced hardness increase in grain-boundary region and significant improvement of material resistance to crack formation.

  6. Lightweight Heat Pipes Made from Magnesium

    NASA Technical Reports Server (NTRS)

    Rosenfeld, John N.; Zarembo, Sergei N.; Eastman, G. Yale

    2010-01-01

    Magnesium has shown promise as a lighter-weight alternative to the aluminum alloys now used to make the main structural components of axially grooved heat pipes that contain ammonia as the working fluid. Magnesium heat-pipe structures can be fabricated by conventional processes that include extrusion, machining, welding, and bending. The thermal performances of magnesium heat pipes are the same as those of equal-sized aluminum heat pipes. However, by virtue of the lower mass density of magnesium, the magnesium heat pipes weigh 35 percent less. Conceived for use aboard spacecraft, magnesium heat pipes could also be attractive as heat-transfer devices in terrestrial applications in which minimization of weight is sought: examples include radio-communication equipment and laptop computers.

  7. Aluminum battery alloys

    DOEpatents

    Thompson, David S.; Scott, Darwin H.

    1985-01-01

    Aluminum alloys suitable for use as anode structures in electrochemical cs are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

  8. Aluminum battery alloys

    DOEpatents

    Thompson, D.S.; Scott, D.H.

    1984-09-28

    Aluminum alloys suitable for use as anode structures in electrochemical cells are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

  9. Magnesium and magnesium alloys

    SciTech Connect

    Avedesian, M.; Baker, H.

    1998-12-31

    This new handbook is the most comprehensive publication of engineering information on commercial magnesium alloys under one cover in the last sixty years. Prepared with the cooperation of the International Magnesium Association, it presents the industrial practices currently used throughout the world, as well as the properties of the products critical to their proper application. Contents include: general characteristics; physical metallurgy; melting, refining, alloying, recycling, and powder production; casting; heat treatment; forging, rolling, and extrusion; semisolid processing; forming; joining; cleaning and finishing; selection, application, and properties of grades and alloys; design considerations; mechanical behavior and wear resistance; fatigue and fracture-mechanics; high-temperature strength and creep; corrosion and stress-corrosion cracking; specification.

  10. ELNES investigations of the oxygen K-edge in spinels.

    PubMed

    Docherty, F T; Craven, A J; McComb, D W; Skakle, J

    2001-02-01

    The results of a systematic study of the oxygen K-edge electron energy-loss spectroscopy (ELNES) from a series of aluminium- and chromium-containing spinels are presented. Extra fine structure in the region up to 10 eV above the edge onset is observed for the chromium-containing compounds and is assigned to transitions to states created by mixing of oxygen 2p and metal 3d orbitals. The experimental data has been simulated using the multiple scattering code, FEFF8. Good agreement was obtained in the case of magnesium aluminate, but relatively poor agreement was obtained in the case of the chromites. The possible fingerprints in the oxygen K-edge ELNES corresponding to a high degree of inversion the spinel structure and to a tetragonal distortion of the cubic structure are discussed.

  11. Room temperature magnesium electrorefining by using non-aqueous electrolyte

    NASA Astrophysics Data System (ADS)

    Park, Jesik; Jung, Yeojin; Kusumah, Priyandi; Dilasari, Bonita; Ku, Heesuk; Kim, Hansu; Kwon, Kyungjung; Lee, Churl Kyoung

    2016-09-01

    The increasing usage of magnesium inevitably leads to a fast increase in magnesium scrap, and magnesium recycling appears extremely beneficial for cost reduction, preservation of natural resources and protection of the environment. Magnesium refining for the recovery of high purity magnesium from metal scrap alloy (AZ31B composed of magnesium, aluminum, zinc, manganese and copper) at room temperature is investigated with a non-aqueous electrolyte (tetrahydrofuran with ethyl magnesium bromide). A high purity (99.999%) of electrorefined magneisum with a smooth and dense surface is obtained after potentiostatic electrolysis with an applied voltage of 2 V. The selective dissolution of magnesium from magnesium alloy is possible by applying an adequate potential considering the tolerable impurity level in electrorefined magnesium and processing time. The purity estimation method suggested in this study can be useful in evaluating the maximum content of impurity elements.

  12. Magnesium for automotive applications: Primary production cost assessment

    NASA Astrophysics Data System (ADS)

    Das, Sujit

    2003-11-01

    Production technologies must be cost effective for primary magnesium to become an economically viable alternative material for wide spread automotive applications. In this article, the prices at which magnesium becomes competitive with aluminum and steel are examined, including magnesium production cost estimates for current and future scenarios using electrolytic and thermal processes. The economic viability of the industry for automotive applications is also examined in the context of magnesium market price, taking into consideration the dynamics of its supply and demand as well.

  13. Isotopically pure magnesium isotope-24 is prepared from magnesium-24 oxide

    NASA Technical Reports Server (NTRS)

    Chellew, N. R.; Schilb, J. D.; Steunenberg, R. K.

    1968-01-01

    Apparatus is used to prepare isotopically pure magnesium isotope-24, suitable for use in neutron scattering and polarization experiments. The apparatus permits thermal reduction of magnesium-24 oxide with aluminum and calcium oxide, and subsequent vaporization of the product metal in vacuum. It uses a resistance-heated furnace tube and cap assembly.

  14. Photoinduced radical processes on the spinel (MgAl2O4) surface involving methane, ammonia, and methane/ammonia.

    PubMed

    Emeline, A V; Abramkin, D A; Zonov, I S; Sheremetyeva, N V; Rudakova, A V; Ryabchuk, V K; Serpone, N

    2012-05-15

    The present study explored photoinduced radical processes caused by interaction of CH(4) and NH(3) with a photoexcited surface of a complex metal oxide: magnesium-aluminum spinel (MgAl(2)O(4); MAS). UV irradiation of MAS in vacuo yielded V-type color centers as evidenced by the 360 nm band in difference diffuse reflectance spectra. Interaction of these H-bearing molecules with photogenerated surface-active hole states (O(S)(-)•) yielded radical species which on recombination produced more complex molecules (including heteroatomic species) relative to the initial molecules. For the MAS/CH(4) system, photoinduced dissociative adsorption of CH(4) on surface-active hole centers produced •CH(3) radicals that recombined to yield CH(3)CH(3). For MAS/NH(3), a similar dissociative adsorption process led to formation of •NH(2) radicals with formation of NH(2)NH(2) as an intermediate product; continued UV irradiation ultimately yielded N(2). For the mixed MAS/CH(4)/NH(3) system, however, interaction of adsorbed NH(3) and CH(4) on the UV-activated surface of MAS yielded •NH(2) and •CH(3) radicals, respectively, which produced CH(3)-NH(2) followed by loss of the remaining hydrogens to form a surface-adsorbed cyanide, CN(S), species. Recombination of photochemically produced radicals released sufficient energy to re-excite the solid spinel, generating new surface-active sites and a flash luminescence (emission decay time at 520 nm, τ ~ 6 s for the MAS/NH(3) case) referred to as the PhICL effect.

  15. Integrated thick-film nanostructures based on spinel ceramics

    PubMed Central

    2014-01-01

    Integrated temperature-humidity-sensitive thick-film structures based on spinel-type semiconducting ceramics of different chemical compositions and magnesium aluminate ceramics were prepared and studied. It is shown that temperature-sensitive thick-film structures possess good electrophysical characteristics in the region from 298 to 358 K. The change of electrical resistance in integrated thick-film structures is 1 order, but these elements are stable in time and can be successfully used for sensor applications. PMID:24670141

  16. 76 FR 7813 - Amended Final Results of the 2008-2009 Antidumping Duty Administrative Review: Pure Magnesium...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-11

    ... chemistry, form or size, unless expressly excluded from the scope of this order. Pure magnesium is a metal... materials into magnesium metal. Pure primary magnesium is used primarily as a chemical in the aluminum... the following alloying elements: Aluminum, manganese, zinc, silicon, thorium, zirconium and...

  17. Magnesium alloy applications in automotive structures

    NASA Astrophysics Data System (ADS)

    Easton, Mark; Beer, Aiden; Barnett, Matthew; Davies, Chris; Dunlop, Gordon; Durandet, Yvonne; Blacket, Stuart; Hilditch, Tim; Beggs, Peter

    2008-11-01

    The use of magnesium alloys in structural applications has great potential for the lightweighting of transportation vehicles. Research within the CAST Cooperative Research Centre has tackled some of the important issues related to the use of magnesium in structural applications. To this end, a new alloy with extrudability and properties similar to 6000 series aluminum alloys has been developed. Furthermore, a method of laser heating magnesium alloys before self-piercing riveting has enabled high-integrity joining between magnesium components or between magnesium and dissimilar metals. In this paper, new technologies and improved understanding of the deformation behavior of wrought magnesium alloys are discussed in light of key metallurgical features such as alloy composition, grain size, and work hardening rate.

  18. A Processing Map for Hot Deformation of an Ultrafine-Grained Aluminum-Magnesium-Silicon Alloy Prepared by Mechanical Milling and Hot Extrusion

    NASA Astrophysics Data System (ADS)

    Asgharzadeh, Hamed; Rahbar Niazi, Masoud; Simchi, Abdolreza

    2015-12-01

    Uniaxial compression test at different temperatures [573 K to 723 K (300 °C to 450 °C)] and strain rates (0.01 to 1 s-1) was employed to study the hot deformation behavior of an ultrafine-grained (UFG) Al6063 alloy prepared by the powder metallurgy route. The UFG alloy with an average grain size of ~0.3 µm was prepared by mechanical milling of a gas-atomized aluminum alloy powder for 20 hours followed by hot powder extrusion at 723 K (450 °C). To elaborate the effect of grain size, the aluminum alloy powder was extruded without mechanical milling to attain a coarse-grained (CG) structure with an average grain size of about 2.2 µm. By employing the dynamic materials model, processing maps for the hot deformation of the UFG and CG Al alloy were constructed. For investigation of microstructural evolutions and deformation instability occurring upon hot working, optical microscopy, scanning electron microscopy coupled with electron backscattered diffraction and transmission electron microscopy were utilized. It is shown that the grain refinement increases the deformation flow stress while reducing the strain hardening and power dissipation efficiency during the deformation process at the elevated temperatures. Restoration mechanisms, including dynamic recovery and recrystallization are demonstrated to control microstructural evolutions and thus the deformation behavior. Coarsening of the grain structure in the UFG alloy is illustrated, particularly when the deformation is performed at high temperatures and low strain rates. The manifestations of instability are observed in the form of cracking and void formation.

  19. New scheme for cation distribution and electrical characterization of nanocrystalline aluminum doped magnesium ferrite MgAlxFe2-xO4

    NASA Astrophysics Data System (ADS)

    Zaki, H. M.; Al-Heniti, S.; Al Shehri, N.

    2014-03-01

    MgAlxFe2-xO4 (x=0.0 up to 1 step 0.2) was prepared using co-precipitation method. The value of lattice constant is found to decrease with increasing Al3+ concentration. The particle size of the samples calculated using the Sherrer formula was obtained in the range of 15-28 nm. The two main bands corresponding to tetrahedral and octahedral sites were observed to be around 600 cm-1 and 450 cm-1, respectively. These bands are shifted to high frequencies with more doping of Al3+ ions which may be attributed to the decrease in the mean radius of the tetrahedral and octahedral sites. The threshold frequency (νth) for the electronic transition decreases with increasing the Al3+content. The tetrahedral force constant (KT) increases continuously with Al3+ concentration.The bandwidth of the tetrahedral site is found to increase gradually with the Al3+ content. The validity of the proposed cation distribution is confirmed by considering the X-ray intensity ratios of diffraction lines sensitive to the tetrahedral and octahedral sites. DC conductivity measurements exhibited metallic and semiconductor-like behavior with temperature for all compositions. The decrease of Curie temperature with the increase of non-magnetic ions of aluminum indicates their preference to the octahedral sites as well and confirms the validity of the cation distribution.

  20. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2011-01-01

    Seawater and natural brines accounted for about 54 percent of U.S. magnesium compounds production in 2010. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties from well brines in Michigan. Caustic-calcined magnesia was recovered from seawater by Premier Magnesia in Florida, from well brines in Michigan by Martin Marietta and from magnesite in Nevada by Premier Magnesia. Intrepid Potash-Wendover and Great Salt Lake Minerals Corp. recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from seawater by SPI Pharma in Delaware and Premier Magnesia in Florida, and by Martin Marietta from its operation mentioned above.

  1. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2010-01-01

    Seawater and natural brines accounted for about 40 percent of U.S. magnesium compounds production in 2009. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties from well brines in Michigan. Caustic-calcined magnesia was recovered from seawater by Premier Chemicals in Florida, from well brines in Michigan by Martin Marietta and from magnesite in Nevada by Premier Chemicals. Intrepid Potash-Wendover, and Great Salt Lake Minerals Corp. recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from seawater by SPI Pharma in Delaware and Premier Chemicals in Florida, and by Martin Marietta from its operation mentioned above.

  2. Rapidly synthesis of nanocrystalline MgIn 2O 4 spinel using combustion and solid state chemistry

    NASA Astrophysics Data System (ADS)

    Surblé, Suzy; Gosset, Dominique; Dollé, Mickaël; Baldinozzi, Gianguido; Urvoy, Stéphane; Siméone, David

    2011-01-01

    Nanometric/submicronic powders of magnesium indate spinel MgIn 2O 4 were prepared with a two-steps process. First, nano-oxides of In 2O 3 and MgO were obtained by combustion of aqueous solutions of metal nitrates (as an oxidizer) and different fuels (glycine/urea/citric acid). Then, the as-prepared combustion ashes were converted into pure spinels after calcinations at elevated temperature. The as-prepared powders spinels have nanometric or submicronic grain size. This process allows preparing the MgIn 2O 4 spinel compound in 1 day whilst 10 days were necessary when the classical solid state chemistry is used. In this paper, we compare these two ways and study the effect of different reaction parameters, such as the nature of fuels or the fuel/oxidiser ratio. Crystallites sizes of the synthesized compounds were investigated by powder X-ray diffraction and Scanning Electron Microscopy.

  3. Production of magnesium metal

    DOEpatents

    Blencoe, James G [Harriman, TN; Anovitz, Lawrence M [Knoxville, TN; Palmer, Donald A [Oliver Springs, TN; Beard, James S [Martinsville, VA

    2010-02-23

    A process of producing magnesium metal includes providing magnesium carbonate, and reacting the magnesium carbonate to produce a magnesium-containing compound and carbon dioxide. The magnesium-containing compound is reacted to produce magnesium metal. The carbon dioxide is used as a reactant in a second process. In another embodiment of the process, a magnesium silicate is reacted with a caustic material to produce magnesium hydroxide. The magnesium hydroxide is reacted with a source of carbon dioxide to produce magnesium carbonate. The magnesium carbonate is reacted to produce a magnesium-containing compound and carbon dioxide. The magnesium-containing compound is reacted to produce magnesium metal. The invention further relates to a process for production of magnesium metal or a magnesium compound where an external source of carbon dioxide is not used in any of the reactions of the process. The invention also relates to the magnesium metal produced by the processes described herein.

  4. Phosphorylation and Interaction with the 14-3-3 Protein of the Plasma Membrane H+-ATPase are Involved in the Regulation of Magnesium-Mediated Increases in Aluminum-Induced Citrate Exudation in Broad Bean (Vicia faba. L).

    PubMed

    Chen, Qi; Kan, Qi; Wang, Ping; Yu, Wenqian; Yu, Yuzhen; Zhao, Yan; Yu, Yongxiong; Li, Kunzhi; Chen, Limei

    2015-06-01

    Several studies have shown that external application of micromolar magnesium (Mg) can increase the resistance of legumes to aluminum (Al) stress by enhancing Al-induced citrate exudation. However, the exact mechanism underlying this regulation remains unknown. In this study, the physiological and molecular mechanisms by which Mg enhances Al-induced citrate exudation to alleviate Al toxicity were investigated in broad bean. Micromolar concentrations of Mg that alleviated Al toxicity paralleled the stimulation of Al-induced citrate exudation and increased the activity of the plasma membrane (PM) H(+)-ATPase. Northern blot analysis shows that a putative MATE-like gene (multidrug and toxic compound extrusion) was induced after treatment with Al for 4, 8 and 12 h, whereas the mRNA abundance of the MATE-like gene showed no significant difference between Al plus Mg and Al-only treatments during the entire treatment period. Real-time reverse transcription-PCR (RT-PCR) and Western blot analyses suggest that the transcription and translation of the PM H(+)-ATPase were induced by Al but not by Mg. In contrast, immunoprecipitation suggests that Mg enhanced the phosphorylation levels of VHA2 and its interaction with the vf14-3-3b protein under Al stress. Taken together, our results suggest that micromolar concentrations of Mg can alleviate the Al rhizotoxicity by increasing PM H(+)-ATPase activity and Al-induced citrate exudation in YD roots. This enhancement is likely to be attributable to Al-induced increases in the expression of the MATE-like gene and vha2 and Mg-induced changes in the phosphorylation levels of VHA2, thus changing its interaction with the vf14-3-3b protein.

  5. Limited subsolidus diffusion in type B1 CAI: Evidence from Ti distribution in spinel

    NASA Technical Reports Server (NTRS)

    Meeker, G. P.; Quick, J. E.; Paque, Julie M.

    1993-01-01

    Most models of calcium aluminum-rich inclusions (CAI) have focused on early stages of formation by equilibrium crystallization of a homogeneous liquid. Less is known about the subsolidus cooling history of CAI. Chemical and isotopic heterogeneties on a scale of tens to hundreds of micrometers (e.g. MacPherson et al. (1989) and Podosek, et al. (1991)) suggest fairly rapid cooling with a minimum of subsolidus diffusion. However, transmission electron microscopy indicates that solid state diffusion may have been an important process at a smaller scale (Barber et al. 1984). If so, chemical evidence for diffusion could provide constraints on cooling times and temperatures. With this in mind, we have begun an investigation of the Ti distribution in spinels from two type B1 CAI from Allende to determine if post-crystallization diffusion was a significant process. The type B1 CAIs, 3529Z and 5241 have been described by Podosek et al. (1991) and by El Goresy et al. (1985) and MacPherson et al. (1989). We have analyzed spinels in these inclusions using the electron microprobe. These spinels are generally euhedral, range in size from less than 10 to 15 micron and are poikilitically enclosed by millimeter-sized pyroxene, melilite, and anorthite. Analyses were obtained from both the mantles and cores of the inclusions. Compositions of pyroxene in the vicinity of individual spinel grains were obtained by analyzing at least two points on opposite sides of the spinel and averaging the compositions. The pyroxene analyses were obtained within 15 microns of the spinel-pyroxene interface. No compositional gradients were observed within single spinel crystals. Ti concentrations in spinels included within pyroxene, melilite, and anorthite are presented.

  6. Development of Rolling Schedules for AZ31 Magnesium Alloy Sheets

    DTIC Science & Technology

    2015-06-01

    received AZ31B, a magnesium (Mg) alloy that contains approximately 3% aluminum and 1% zinc. In particular, we investigated the ability to roll AZ31B to...ARL-TR-7277 ● JUNE 2015 US Army Research Laboratory Development of Rolling Schedules for AZ31 Magnesium Alloy Sheets by...7277 ● JUNE 2015 US Army Research Laboratory Development of Rolling Schedules for AZ31 Magnesium Alloy Sheets by Laszlo Kecskes, Heidi

  7. Dissolution and Separation of Aluminum and Aluminosilicates

    SciTech Connect

    McFarlane, Joanna; Benker, Dennis; DePaoli, David W.; Felker, Leslie Kevin; Mattus, Catherine H.

    2015-12-19

    The selection of an aluminum alloy for target irradiation affects post-irradiation target dissolution and separations. Recent tests with aluminum alloy 6061 yielded greater than expected precipitation in the dissolver, forming up to 10 wt.% solids of aluminum hydroxides and aluminosilicates. Aluminosilicate dissolution presents challenges in a number of different areas, metals extraction from minerals, flyash treatment, and separations from aluminum alloys. We present experimental work that attempts to maximize dissolution of aluminum metal, along with silicon, magnesium, and copper impurities, through control of temperature, the rate of reagent addition, and incubation time. Aluminum phase transformations have been identified as a function of time and temperature, using X-ray diffraction. Solutions have been analyzed using wet chemical methods and X-ray fluorescence. Our data have been compared with published calculations of aluminum phase diagrams. Approaches are given to enhance the dissolution of aluminum and aluminosilicate phases in caustic solution.

  8. Dissolution and Separation of Aluminum and Aluminosilicates

    DOE PAGES

    McFarlane, Joanna; Benker, Dennis; DePaoli, David W.; ...

    2015-12-19

    The selection of an aluminum alloy for target irradiation affects post-irradiation target dissolution and separations. Recent tests with aluminum alloy 6061 yielded greater than expected precipitation in the dissolver, forming up to 10 wt.% solids of aluminum hydroxides and aluminosilicates. Aluminosilicate dissolution presents challenges in a number of different areas, metals extraction from minerals, flyash treatment, and separations from aluminum alloys. We present experimental work that attempts to maximize dissolution of aluminum metal, along with silicon, magnesium, and copper impurities, through control of temperature, the rate of reagent addition, and incubation time. Aluminum phase transformations have been identified as amore » function of time and temperature, using X-ray diffraction. Solutions have been analyzed using wet chemical methods and X-ray fluorescence. Our data have been compared with published calculations of aluminum phase diagrams. Approaches are given to enhance the dissolution of aluminum and aluminosilicate phases in caustic solution.« less

  9. Selective Adsorption of Sodium Aluminum Fluoride Salts from Molten Aluminum

    SciTech Connect

    Leonard S. Aubrey; Christine A. Boyle; Eddie M. Williams; David H. DeYoung; Dawid D. Smith; Feng Chi

    2007-08-16

    Aluminum is produced in electrolytic reduction cells where alumina feedstock is dissolved in molten cryolite (sodium aluminum fluoride) along with aluminum and calcium fluorides. The dissolved alumina is then reduced by electrolysis and the molten aluminum separates to the bottom of the cell. The reduction cell is periodically tapped to remove the molten aluminum. During the tapping process, some of the molten electrolyte (commonly referred as “bath” in the aluminum industry) is carried over with the molten aluminum and into the transfer crucible. The carryover of molten bath into the holding furnace can create significant operational problems in aluminum cast houses. Bath carryover can result in several problems. The most troublesome problem is sodium and calcium pickup in magnesium-bearing alloys. Magnesium alloying additions can result in Mg-Na and Mg-Ca exchange reactions with the molten bath, which results in the undesirable pickup of elemental sodium and calcium. This final report presents the findings of a project to evaluate removal of molten bath using a new and novel micro-porous filter media. The theory of selective adsorption or removal is based on interfacial surface energy differences of molten aluminum and bath on the micro-porous filter structure. This report describes the theory of the selective adsorption-filtration process, the development of suitable micro-porous filter media, and the operational results obtained with a micro-porous bed filtration system. The micro-porous filter media was found to very effectively remove molten sodium aluminum fluoride bath by the selective adsorption-filtration mechanism.

  10. Production of magnesium metal

    DOEpatents

    Blencoe, James G [Harriman, TN; Anovitz, Lawrence M [Knoxville, TN; Palmer, Donald A [Oliver Springs, TN; Beard, James S [Martinsville, VA

    2012-04-10

    A process of producing magnesium metal includes providing magnesium carbonate, and reacting the magnesium carbonate to produce a magnesium-containing compound and carbon dioxide. The magnesium-containing compound is reacted to produce magnesium metal. The carbon dioxide is used as a reactant in a second process. In another embodiment of the process, a magnesium silicate is reacted with a caustic material to produce magnesium hydroxide. The magnesium hydroxide is reacted with a source of carbon dioxide to produce magnesium carbonate. The magnesium carbonate is reacted to produce a magnesium-containing compound and carbon dioxide. The magnesium-containing compound is reacted to produce magnesium metal. The invention also relates to the magnesium metal produced by the processes described herein.

  11. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2012-01-01

    Seawater and natural brines accounted for about 57 percent of magnesium compounds produced in the United States in 2011. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties LLC from well brines in Michigan. Caustic-calcined magnesia was recovered from seawater by Premier Magnesia LLC in Florida, from well brines in Michigan by Martin Marietta and from magnesite in Nevada by Premier Magnesia. Intrepid Potash Wendover LLC and Great Salt Lake Minerals Corp. recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from seawater by SPI Pharma Inc. in Delaware and Premier Magnesia in Florida, and by Martin Marietta from its brine operation in Michigan.

  12. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2002-01-01

    Seawater and natural brines accounted for about 60% of US magnesium compounds production in 2001. Dead-burned and caustic-calcined magnesias were recovered from seawater in Florida by Premier Chemicals. They were also recovered from Michigan well brines by Dow Chemical, Martin Marietta Magnesia Specialties and Rohm & Haas. And Premier Chemicals recovered dead-burned and caustic-calcined magnesias from magnesite in Nevada. Reilly Industries and Great Salt Lake Minerals recovered magnesium chloride brines from the Great Salt Lake in Utah.

  13. Assessment of the magnesium primary production technology. Final report

    SciTech Connect

    Flemings, M.C.; Kenney, G.B.; Sadoway, D.R.; Clark, J.P.; Szekely, J.

    1981-02-01

    At current production levels, direct energy savings achievable in primary magnesium production are 1.2 milliquads of energy per annum. Were magnesium to penetrate the automotive market to an average level of 50 pounds per vehicle, the resultant energy savings at the production stage would be somewhat larger, but the resulting savings in gasoline would conserve an estimated 325 milliquads of energy per year. The principal barrier to more widespread use of magnesium in the immediate future is its price. A price reduction of magnesium of 10% would lead to widespread conversion of aluminum die and permanent mold castings to magnesium. This report addresses the technology of electrolytic and thermic magnesium production and the economics of expanded magnesium production and use.

  14. Oxygen isotopes in spinels from Antarctic micrometeorites

    NASA Astrophysics Data System (ADS)

    Kurat, G.; Hoppe, P.; Walter, J.; Engrand, C.; Maurette, M.

    1994-07-01

    Spinel-rich inclusions were found in a large unmelted micrometeorite (MM) from Antarctica. This particle (MM92/15-23) consists of a fine-grained matrix of dehydrated former phyllosilicates that enclose a few small olivines, one large chromite, and several spinel-rich inclusions. The latter form elongated to rounded bodies up to 35 microns in length and consist of a spinel core enveloped by a Fe-rich silicate phase that probably is a (dehydrated?) phyllosilicate -- too small to be analyzed with the electron microprobe. A few very small perovskite grains are enclosed within the spinel. The chemical composition of the spinel is that of a Mg-Al spinel. On top of the Fe-rich silicate envelopes there is a discontinuous rim of aluminous Ca-rich pyroxene with a fairly high FeO content. The trace-element content is determined by secondary ion mass spectrometry (SIMS) of these inclusions resembles that of group II CAIs. Meanwhile we have found a second Antartic micrometeorite containing a few spinel grains. This spinel is associated with some tiny ilmenite grains and embedded in the foamy melt matrix of scoriaceous micrometeorite particle MM94/1-28. The chemical composition of the spinel is that of a Mg-Al-spinel containing small amounts of FeO (0.6 wt%), but no Cr2O3. We have successfully analyzed the O isotopic composition of two spinels from MM92/15-23 and one from MM94/1-28. The most common matter accreting onto the Earth today and represented by unmelted and partially melted micrometeorites consists of a matter similar, but not identical, to CM carbonaceous chondrites. The presence of spinel-rich Ca-Al rich inclusions (CAIs) with trace-element contents and O isotopic compositions of group II inclusions provides an additional support of that view.

  15. Magnesium Test

    MedlinePlus

    ... too much. Deficiencies are typically seen with: Low dietary intake (seen in the elderly, malnourished , and with alcoholism ) Gastrointestinal disorders (such as Crohn's disease) Uncontrolled ... blood levels of magnesium are rarely due to dietary sources but are usually the result of an ...

  16. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2004-01-01

    Dead-burned and caustic-calcined magnesias were recovered from seawater by Premier Chemicals in Florida; from well brines in Michigan by Dow Chemical, Martin Marietta Magnesia Specialties, and Rohm & Haas; and from magnesite in Nevada by Premier Chemicals. Reilly Industries and Great Salt Lake Minerals recovered magnesium chloride brines from the Great Salt Lake in Utah.

  17. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2007-01-01

    Seawater and natural brines accounted for about 52 percent of U.S. magnesium compounds production in 2006. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties from well brines in Michigan. Caustic-calcined magnesia was recovered from sea-water by Premier Chemicals in Florida; from well brines in Michigan by Martin Marietta and Rohm and Haas; and from magnesite in Nevada by Premier Chemicals. Intrepid Potash-Wendover and Great Salt Lake Minerals recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from brucite by Applied Chemical Magnesias in Texas, from seawater by SPI Pharma in Delaware and Premier Chemicals in Florida, and by Martin Marietta and Rohm and Haas from their operations mentioned above. About 59 percent of the magnesium compounds consumed in the United States was used for refractories that are used mainly to line steelmaking furnaces. The remaining 41 percent was consumed in agricultural, chemical, construction, environmental and industrial applications.

  18. Tagnite and Keronite Assessment on Magnesium & Aluminum

    DTIC Science & Technology

    2014-11-19

    8” nozzle , 10” standoff, 80 degree angle, & 25 psi nozzle pressure  Acceptable coating removal rate determined to be between 0.3-0.5 ft2/min...Propulsion Directorate CEE-BEE 300 FLM Degreaser, 25 minutes, 150F, ultrasonic tank CEE-BEE 300 FLM Degreaser, 25 minutes, 150F, ultrasonic tank DI

  19. Magnesium Aluminum Borides as Explosive Materials

    DTIC Science & Technology

    2011-12-20

    5 Crystal Structure 7 Lithium Substitutions 9 Comparative Properties 9 Selection of Four Borides for...List of Tables Table Title Page 1 Physical Properties and Cost of Selected Metals 10 2 Thermochemical Properties of...Selected Metals at 1000 K 10 3 Physical Properties and Cost of Selected Compounds 11 4 Thermochemical Properties of Selected Compounds at 1000

  20. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2003-01-01

    Seawater and natural brines accounted for about 60 percent of U.S. magnesium compounds production during 2002. Dead-burned and caustic-calcined magnesias were recovered from seawater by Premier Chemicals in Florida. They were also recovered from well brines in Michigan by Dow Chemical, Martin Marietta Magnesia Specialties and Rohm & Haas. And they were recovered from magnesite in Nevada by Premier Chemicals.

  1. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2006-01-01

    In 2005, seawater and natural brines accounted for 51% of US magnesium compounds production. World magnesia production was estimated to be 14.5 Mt. Most of the production came from China, North Korea, Russia and Turkey. Although no specific production figures are available, Japan and the United States are estimated to account for almost one-half of the world's capacity from seawater and brines.

  2. Magnesium in diet

    MedlinePlus

    ... sources of magnesium: Fruits or vegetables (such as bananas, dried apricots, and avocados) Nuts (such as almonds ... Supplements, National Institutes of Health. Dietary Supplement Fact Sheet: Magnesium . ods.od.nih.gov/factsheets/Magnesium-Consumer . ...

  3. Low magnesium level

    MedlinePlus

    Low magnesium level is a condition in which the amount of magnesium in the blood is lower than normal. The medical ... that convert or use energy ( metabolism ). When the level of magnesium in the body drops below normal, ...

  4. MgGa2O4 spinel barrier for magnetic tunnel junctions: Coherent tunneling and low barrier height

    NASA Astrophysics Data System (ADS)

    Sukegawa, Hiroaki; Kato, Yushi; Belmoubarik, Mohamed; Cheng, P.-H.; Daibou, Tadaomi; Shimomura, Naoharu; Kamiguchi, Yuuzo; Ito, Junichi; Yoda, Hiroaki; Ohkubo, Tadakatsu; Mitani, Seiji; Hono, Kazuhiro

    2017-03-01

    Epitaxial Fe/magnesium gallium spinel oxide (MgGa2O4)/Fe(001) magnetic tunnel junctions (MTJs) were fabricated by magnetron sputtering. A tunnel magnetoresistance (TMR) ratio up to 121% at room temperature (196% at 4 K) was observed, suggesting a TMR enhancement by the coherent tunneling effect in the MgGa2O4 barrier. The MgGa2O4 layer had a spinel structure and it showed good lattice matching with the Fe layers owing to slight tetragonal lattice distortion of MgGa2O4. Barrier thickness dependence of the tunneling resistance and current-voltage characteristics revealed that the height of the MgGa2O4 barrier is much lower than that of an MgAl2O4 barrier. This study demonstrates the potential of Ga-based spinel oxides for MTJ barriers having a large TMR ratio at a low resistance area product.

  5. The Spinel Explorer--Interactive Visual Analysis of Spinel Group Minerals.

    PubMed

    Luján Ganuza, María; Ferracutti, Gabriela; Gargiulo, María Florencia; Castro, Silvia Mabel; Bjerg, Ernesto; Gröller, Eduard; Matković, Krešimir

    2014-12-01

    Geologists usually deal with rocks that are up to several thousand million years old. They try to reconstruct the tectonic settings where these rocks were formed and the history of events that affected them through the geological time. The spinel group minerals provide useful information regarding the geological environment in which the host rocks were formed. They constitute excellent indicators of geological environments (tectonic settings) and are of invaluable help in the search for mineral deposits of economic interest. The current workflow requires the scientists to work with different applications to analyze spine data. They do use specific diagrams, but these are usually not interactive. The current workflow hinders domain experts to fully exploit the potentials of tediously and expensively collected data. In this paper, we introduce the Spinel Explorer-an interactive visual analysis application for spinel group minerals. The design of the Spinel Explorer and of the newly introduced interactions is a result of a careful study of geologists' tasks. The Spinel Explorer includes most of the diagrams commonly used for analyzing spinel group minerals, including 2D binary plots, ternary plots, and 3D Spinel prism plots. Besides specific plots, conventional information visualization views are also integrated in the Spinel Explorer. All views are interactive and linked. The Spinel Explorer supports conventional statistics commonly used in spinel minerals exploration. The statistics views and different data derivation techniques are fully integrated in the system. Besides the Spinel Explorer as newly proposed interactive exploration system, we also describe the identified analysis tasks, and propose a new workflow. We evaluate the Spinel Explorer using real-life data from two locations in Argentina: the Frontal Cordillera in Central Andes and Patagonia. We describe the new findings of the geologists which would have been much more difficult to achieve using the

  6. Surface electrical conductivity of single crystal spinel in cesium vapor. Final report

    SciTech Connect

    Agnew, P.; Ing, J.L.

    1995-04-02

    The operation of a thermionic fuel element (TFE) requires the maintenance of good electrical resistance between the anode and cathode, and between the electrodes and the TFE body. A program of research was established as part of the TOPAZ International Program (TIP) with the purpose of investigating the degradation of TFE electrical insulators. The major emphasis of this research has been on the interactions of oxide ceramics with cesium (Cs) vapor, and the resurfacing decrease of surface resistivity. Previous work has studied the surface electrical conductivity of sapphire exposed to Cs. In this report the authors describe the results of an experimental investigation of the surface electrical conductivity of single crystal magnesium aluminate spinel at temperatures ranging from 573K to 923K, in the presence of cesium vapor at pressures up to 1 Torr. The interest in spinel has arisen in view of its apparent resistance to radiation damage.

  7. Spinel-structured surface layers for facile Li ion transport and improved chemical stability of lithium manganese oxide spinel

    NASA Astrophysics Data System (ADS)

    Lee, Hae Ri; Seo, Hyo Ree; Lee, Boeun; Cho, Byung Won; Lee, Kwan-Young; Oh, Si Hyoung

    2017-01-01

    Li-ion conducting spinel-structured oxide layer with a manganese oxidation state close to being tetravalent was prepared on aluminum-doped lithium manganese oxide spinel for improving the electrochemical performances at the elevated temperatures. This nanoscale surface layer provides a good ionic conduction path for lithium ion transport to the core and also serves as an excellent chemical barrier for protecting the high-capacity core material from manganese dissolution into the electrolyte. In this work, a simple wet process was employed to prepare thin LiAlMnO4 and LiMg0.5Mn1.5O4 layers on the surface of LiAl0.1Mn1.9O4. X-ray absorption studies revealed an oxidation state close to tetravalent manganese on the surface layer of coated materials. Materials with these surface coating layers exhibited excellent capacity retentions superior to the bare material, without undermining the lithium ion transport characteristics and the high rate performances.

  8. Aluminum Hydroxide

    MedlinePlus

    Aluminum hydroxide is used for the relief of heartburn, sour stomach, and peptic ulcer pain and to ... Aluminum hydroxide comes as a capsule, a tablet, and an oral liquid and suspension. The dose and ...

  9. Investigation of Synthetic Mg(1.3)V(1.7)O4 Spinel with MgO Inclusions: Case Study of a Spinel with an Apparently occupied Interstitial Site

    NASA Technical Reports Server (NTRS)

    Uchida, Hinako; Righter, Kevin; Lavina, Barbara; Nowell, Matthew M.; Wright, Stuart I.; Downs, Robert T.; Yang, Hexiong

    2007-01-01

    A magnesium vanadate spinel crystal, ideally MgV2O4, synthesized at 1 bar, 1200 C and equilibrated under FMQ + 1.3 log f(sub o2) condition, was investigated using single-crystal X-ray diffraction, electron microprobe, and electron backscatter (EBSD). The initial X-ray structure refinements gave tetrahedral and octahedral site occupancies, along with the presence of 0.053 apfu Mg at an interstitial octahedral site . Back-scattered electron (BSE) images and electron microprobe analyses revealed the existence of an Mg-rich phase in the spinel matrix, which was too small (less than or equal to 3microns) for an accurate chemical determination. The EBSD analysis combined with X-ray energy dispersive spectroscop[y (XEDS) suggested that the Mg-rich inclusions are periclase oriented coherently with the spinel matrix. The final structure refinements were optimized by subtracting the X-ray intensity contributions (approx. 9%) of periclase reflections, which eliminated the interstitial Mg. This study provides insight into possible origins of refined interstitial cations reported in the the literature for spinel, and points to the difficulty of using only X-ray diffraction data to distinguish a spinel with interstitial cations from one with coherently oriented MgO inclusions.

  10. Au on MgAl2O4 spinels: The effect of support surface properties in glycerol oxidation

    SciTech Connect

    Villa, Alberto; Gaiassi, Aureliano; Rossetti, Ilenia; Bianchi, Claudia; van Benthem, Klaus; Veith, Gabriel M; Prati, Laura

    2010-01-01

    Here we investigated the properties of Au nanoparticles, prepared via three different techniques and supported on three different MgAl2O4 spinels. The surface composition and area of the spinel plays an important role in determining the selectivity of the catalyst in the selective oxidation of glycerol. it was found that aluminum rich surfaces enhance the C-C bond cleavage reaction for large gold particles which is opposite of what is normally observed for large clusters which typically show no C-C cleavage. We also report that similarly sized AuNPs on the different MgAl2O4 spinels with the same surface Al/Mg ratio, show a similar selectivity; however activity depends on surface area.

  11. Major and Minor Constituents of Aluminum Alloys

    DTIC Science & Technology

    1986-03-01

    sample alloys obtained by both techniques. Keywords: Atomic Absorption Spectroscopy (AAS), Inductively Coupled Plasma Atomic Emission Spectroscopy(ICP-AES).... absorption spectroscopy and inductively coupled plasma atomic emission spectroscopy are used for the determination of major magnesium, lithium, copper, zinc...An accurate analysis of aluminum alloys is required for quality control and characterization purposes. The two analytical techniques atomic

  12. The morphological diagram of spinels

    SciTech Connect

    Ziolkowski, J.

    1996-02-01

    Catalytic anisotropy in mild oxidation reactions results from the varying activity of different crystal faces. Here, spinels exposing (100), (110), and (111) faces have been considered and their Curie-Wulff plots have been drawn, admitting that the relative G(hkl) surface free energies may change in a wide range as a function of composition, inversion, and segregation degree. The normalized free surface energies are defined as A = G(100)/G(111), B = G(110)/G(111), and C = G(111)/G(111) = 1 = const. This made it possible to construct bidimensional morphological diagrams (morphology = f(A,B) at C = const) in the exposed-face-type, solid-type, and exposure-percentage versions. Eleven morphological habits of grains have been identified, including (100)-cube, (110)-dodecahedron, (111)-hexagons, 18-hedron, 20-hedron, and up to 26-hedra bordered with (i) 6 (100)-octagons, 12 (110)-rectangles, and 8 (111)-hexagons, (ii) 6 (100)-squares, 12 (110)-rectangles, and 8 (111)-triangles, or (iii) 6 (100)-squares, 12 (110)-octagons, and 8 (100)-triangles. The analysis is valid for all compounds crystallizing in the cubic system and preferentially exposing the three enumerated faces.

  13. Efficient One-Step Electrolytic Recycling of Low-Grade and Post-Consumer Magnesium Scrap

    SciTech Connect

    Adam C. Powell, IV

    2012-07-19

    Metal Oxygen Separation Technologies, Inc. (abbreviated MOxST, pronounced most) and Boston University (BU) have developed a new low-cost process for recycling post-consumer co-mingled and heavily-oxidized magnesium scrap, and discovered a new chemical mechanism for magnesium separations in the process. The new process, designated MagReGenTM, is very effective in laboratory experiments, and on scale-up promises to be the lowest-cost lowest-energy lowest-impact method for separating magnesium metal from aluminum while recovering oxidized magnesium. MagReGenTM uses as little as one-eighth as much energy as today's methods for recycling magnesium metal from comingled scrap. As such, this technology could play a vital role in recycling automotive non-ferrous metals, particularly as motor vehicle magnesium/aluminum ratios increase in order to reduce vehicle weight and increase efficiency.

  14. Serpentine ore microtextures occurring in the magnola magnesium process

    NASA Astrophysics Data System (ADS)

    Chen, T. T.; Dutrizac, J. E.; White, Carl

    2000-04-01

    Serpentine ore was leached at 95°C and 100°C in 7.0 M HCl media to study the reactions occurring in Noranda’s Magnola magnesium process. Magnesium leaches rapidly from the serpentine Mg3Si2O5(OH)4, and the silicon remains in-situ as an amorphous silica pseudomorph after the original serpentine particles. Negligible silica dissolution occurs, and silica gelation was never observed. The reaction interface extends over 300 400 µm; as a consequence, fine grinding does not significantly accelerate the rate of magnesium dissolution. Associated inclusions of brucite Mg(OH)2, awaruite Ni8Fe3, and magnetite Fe3O4 dissolve rapidly; whereas, chromite FeCr2O4 and a chromium-rich spinel (Cr,Fe,Al,Mg)3O4 remain largely unaffected.

  15. Anomalous bulk modulus in vanadate spinels

    NASA Astrophysics Data System (ADS)

    Li, Z.-Y.; Li, X.; Cheng, J.-G.; Marshall, L. G.; Li, X.-Y.; dos Santos, A. M.; Yang, W.-G.; Wu, J. J.; Lin, J.-F.; Henkelman, G.; Okada, T.; Uwatoko, Y.; Cao, H. B.; Zhou, H. D.; Goodenough, J. B.; Zhou, J.-S.

    2016-10-01

    All single-valent oxide spinels are insulators. The relatively small activation energy in the temperature dependence of resistivity in vanadate spinels led to the speculation that the spinels are near the crossover from localized to itinerant electronic behavior, and the crossover could be achieved under pressure. We have performed a number of experiments and calculations aimed at obtaining information regarding structural changes under high pressure for the whole series of vanadate spinels, as well as transport and magnetic properties under pressure for Mg V2O4 . We have also studied the crystal structure under pressure of wide-gap insulators A C r2O4 (A =Mg , Mn, Fe, Zn) for comparison. Moreover, the relationship between the bulk modulus and the cell volume of A V2O4 (A =Mg , Mn, Fe, Co, Zn) has been simulated by a density functional theory calculation. The proximity of A V2O4 spinels to the electronic state crossover under high pressure has been tested by three criteria: (1) a predicted critical V-V bond length, (2) the observation of a sign change in the pressure dependence of Néel temperature, and (3) measurement of a reduced bulk modulus. The obtained results indicate that, although the crossover from localized to itinerant π bonding V-3 d electrons in the A V2O4 spinels is approached by reducing under pressure the V-V separation R , the critical separation Rc is not reached by 20 GPa in Co V2O4 , which has the smallest V-V separation in the A V2O4 (A =Mg , Mn, Fe, Co, Zn) spinels.

  16. Activity of Cu{sup 2+} ions on the tetrahedral and octahedral sites of spinel oxide catalysts for CO oxidation

    SciTech Connect

    Ghose, J.; Murthy, K.S.R.C.

    1996-09-01

    In studies of CO oxidation on substituted copper chromite spinel oxide catalyst decreases as the Cu{sup 2+} content of the catalyst decreases, either by substitution with a divalent ion, i.e., Cu{sub 1-x} Mg{sub x} [Cr{sub 2}]O{sub 4}, or by reduction of Cu{sup 2+} to Cu{sup 1+}. Crystallographic studies have shown that Cu[Cr{sub 2}]O{sub 4} changes from normal to partially inverse when Cr{sup 3+} is replaced by Al{sup 3+}. Thus, in aluminum-substituted copper chromite catalysts, copper is present on both tetrahedral and octahedral sites of the spinel lattice, i.e., Cu{sub 1-x}Al{sub x} [Cu{sub x}Cr{sub 2-(x+y)}Al{sub y}]O{sub 4}. ESCA studies have shown that upon Al substitution some of the tetrahedral Cu{sup 2+} ions are reduced to Cu{sup 1+} and this causes a reduction in the catalytic activity of the catalysts. The present work was taken up to compare the activity of Cu{sup 2+} on tetrahedral sites with that on octahedral sites of the spinel oxide catalysts. For this, CO oxidation studies were carried out on the inverse spinel CuFe{sub 2}O{sub 4} and on the normal spinel CuRh{sub 2}O{sub 4} catalysts. 7 refs., 1 fig.

  17. Synthesis of nanocrystalline (Co, Ni)Al2O4 spinel powder by mechanical milling of quasicrystalline materials.

    PubMed

    Yadav, T P; Mukhopadhyay, N K; Tiwari, R S; Srivastava, O N

    2007-02-01

    In the present study, attempts have been made to synthesize the nano-crystalline (Co, Ni)Al2O4 spinel powders by ball milling and subsequent annealing. An alloy of Al70Co15Ni15, exhibiting the formation of a complex intermetallic compound known as decagonal quasicrystal is selected as the starting material for mechanical milling. It is interesting to note that this alloy is close to the stoichiometry of aluminum and transition metal atoms required to form the aluminate spinel. The milling was carried out in an attritor mill at 400 rpm for 40 hours with ball to powder ratio of 20 : 1 in hexane medium. Subsequent to this annealing was performed in an air ambience for 10, 20, and 40 h at 600 degrees C in side the furnace in order to oxidize the decagonal phase and finally to form the spinel structure. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the formation of nano-sized decagonal phase after milling and then (Co, Ni)Al2O4 spinel type phase after annealing. The XRD studies reveal the lattice parameter to be 8.075 angstroms and the lattice strain as 0.6%. The XRD and TEM explorations of spinel phase indicate the average grain size to be approximately 40 nm.

  18. Aluminum Alloy and Article Cast Therefrom

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A. (Inventor); Chen, Po-Shou (Inventor)

    2003-01-01

    A cast article from an aluminum alloy, which has improved mechanical properties at elevated temperatures, has the following composition in weight percent: Silicon 14 - 25.0, Copper 5.5 - 8.0, Iron 0.05 - 1.2, Magnesium 0.5 - 1.5, Nickel 0.05 - 0.9, Manganese 0.05 - 1.0, Titanium 0.05 - 1.2, Zirconium 0.05 - 1.2, Vanadium 0.05 - 1.2, Zinc 0.05 - 0.9, Phosphorus 0.001 - 0.1, and the balance is Aluminum, wherein the silicon-to-magnesium ratio is 10 - 25, and the copper-to-magnesium ratio is 4 - 15. The aluminum alloy contains a simultaneous dispersion of three types of Al3X compound particles (X=Ti, V, Zr) having a LI2, crystal structure, and their lattice parameters are coherent to the aluminum matrix lattice. A process for producing this cast article is also disclosed, as well as a metal matrix composite, which includes the aluminum alloy serving as a matrix and containing up to about 60% by volume of a secondary filler material.

  19. Phase control of Mn-based spinel films via pulsed laser deposition

    SciTech Connect

    Feng, Zhenxing; Chen, Xiao; Fister, Timothy T.; Bedzyk, Michael J.; Fenter, Paul

    2016-07-06

    Phase transformations in battery cathode materials during electrochemical-insertion reactions lead to capacity fading and low cycle life. One solution is to keep the same phase of cathode materials during cation insertion-extraction processes. Here, we demonstrate a novel strategy to control the phase and composition of Mn-based spinel oxides for magnesium-ion battery applications through the growth of thin films on lattice-matched substrates using pulsed laser deposition. Materials at two extreme conditions are considered: fully discharged cathode MgMn2O4 and fully charged cathode Mn2O4. The tetragonal MgMn2O4 (MMO) phase is obtained on MgAl2O4 substrates, while the cubic MMO phase is obtained on MgO substrates. Similarly, growth of the empty Mn2O4 spinel in the cubic phase is obtained on an MgO substrate. These results demonstrate the ability to control separately the phase of spinel thin films (e.g., tetragonal vs. cubic MMO) at nominally fixed composition, and to maintain a fixed (cubic) phase while varying its composition (MgxMn2O4, for x = 0, 1). As a result, this capability provides a novel route to gain insights into the operation of battery electrodes for energy storage applications.

  20. Stabilization of MgAl2O4 spinel surfaces via doping

    DOE PAGES

    Hasan, Md. M.; Dholabhai, Pratik P.; Castro, Ricardo H. R.; ...

    2016-02-06

    Here, the surface structure of complex oxides plays a vital role in processes such as sintering, thin film growth, and catalysis, as well as being a critical factor determining the stability of nanoparticles. We report atomistic calculations of the low-index stoichiometric magnesium aluminate spinel (MgAl2O4) surfaces, each with two different chemical terminations. High temperature annealing was used to explore the potential energy landscape and provide more stable surface structures. We find that the lowest energy surface is {100} while the highest energy surface is {111}. The surfaces were subsequently doped with three trivalent dopants (Y3+, Gd3+, La3+) and one tetravalentmore » dopant (Zr4+) and both the surface segregation energies of the dopants and surface energies of the doped surface were determined. All of the dopants reduce the surface energy of spinel, though this reduction in energy depends on both the size and valence of the dopant. Dopants with larger ionic radius tend to segregate to the surface more strongly and reduce the surface energy to a greater extent. Furthermore, the ionic valence of the dopants seems to have a stronger influence on the segregation than does ionic size. For both undoped and doped spinel, the predicted crystal shape is dominated by {100} surfaces, but the relative fraction of the various surfaces changes with doping due to the unequal changes in energy, which has implications on equilibrium nanoparticle shapes and therefore on applications sensitive to surface properties.« less

  1. Stabilization of MgAl2O4 spinel surfaces via doping

    NASA Astrophysics Data System (ADS)

    Hasan, Md. M.; Dholabhai, Pratik P.; Castro, Ricardo H. R.; Uberuaga, Blas P.

    2016-07-01

    Surface structure of complex oxides plays a vital role in processes such as sintering, thin film growth, and catalysis, as well as being a critical factor determining the stability of nanoparticles. Here, we report atomistic calculations of the low-index stoichiometric magnesium aluminate spinel (MgAl2O4) surfaces, each with two different chemical terminations. High temperature annealing was used to explore the potential energy landscape and provide more stable surface structures. We find that the lowest energy surface is {100} while the highest energy surface is {111}. The surfaces were subsequently doped with three trivalent dopants (Y3+, Gd3+, La3+) and one tetravalent dopant (Zr4+) and both the surface segregation energies of the dopants and surface energies of the doped surface were determined. All of the dopants reduce the surface energy of spinel, though this reduction in energy depends on both the size and valence of the dopant. Dopants with larger ionic radius tend to segregate to the surface more strongly and reduce the surface energy to a greater extent. Furthermore, the ionic valence of the dopants seems to have a stronger influence on the segregation than does ionic size. For both undoped and doped spinel, the predicted crystal shape is dominated by {100} surfaces, but the relative fraction of the various surfaces changes with doping due to the unequal changes in energy, which has implications on equilibrium nanoparticle shapes and therefore on applications sensitive to surface properties.

  2. Phase control of Mn-based spinel films via pulsed laser deposition

    DOE PAGES

    Feng, Zhenxing; Chen, Xiao; Fister, Timothy T.; ...

    2016-07-06

    Phase transformations in battery cathode materials during electrochemical-insertion reactions lead to capacity fading and low cycle life. One solution is to keep the same phase of cathode materials during cation insertion-extraction processes. Here, we demonstrate a novel strategy to control the phase and composition of Mn-based spinel oxides for magnesium-ion battery applications through the growth of thin films on lattice-matched substrates using pulsed laser deposition. Materials at two extreme conditions are considered: fully discharged cathode MgMn2O4 and fully charged cathode Mn2O4. The tetragonal MgMn2O4 (MMO) phase is obtained on MgAl2O4 substrates, while the cubic MMO phase is obtained on MgOmore » substrates. Similarly, growth of the empty Mn2O4 spinel in the cubic phase is obtained on an MgO substrate. These results demonstrate the ability to control separately the phase of spinel thin films (e.g., tetragonal vs. cubic MMO) at nominally fixed composition, and to maintain a fixed (cubic) phase while varying its composition (MgxMn2O4, for x = 0, 1). As a result, this capability provides a novel route to gain insights into the operation of battery electrodes for energy storage applications.« less

  3. Production of Magnesium and Aluminum-Magnesium Alloys from Recycled Secondary Aluminum Scrap Melts

    NASA Astrophysics Data System (ADS)

    Gesing, Adam J.; Das, Subodh K.; Loutfy, Raouf O.

    2016-02-01

    An experimental proof of concept was demonstrated for a patent-pending and trademark-pending RE12™ process for extracting a desired amount of Mg from recycled scrap secondary Al melts. Mg was extracted by electrorefining, producing a Mg product suitable as a Mg alloying hardener additive to primary-grade Al alloys. This efficient electrorefining process operates at high current efficiency, high Mg recovery and low energy consumption. The Mg electrorefining product can meet all the impurity specifications with subsequent melt treatment for removing alkali contaminants. All technical results obtained in the RE12™ project indicate that the electrorefining process for extraction of Mg from Al melt is technically feasible. A techno-economic analysis indicates high potential profitability for applications in Al foundry alloys as well as beverage—can and automotive—sheet alloys. The combination of technical feasibility and potential market profitability completes a successful proof of concept. This economical, environmentally-friendly and chlorine-free RE12™ process could be disruptive and transformational for the Mg production industry by enabling the recycling of 30,000 tonnes of primary-quality Mg annually.

  4. Choline Magnesium Trisalicylate

    MedlinePlus

    Choline magnesium trisalicylate is used to relieve the pain, tenderness, inflammation (swelling), and stiffness caused by arthritis ... painful shoulder. It is also used to relieve pain and lower fever. Choline magnesium trisalicylate is in ...

  5. High-pressure transformation in the cobalt spinel ferrites

    SciTech Connect

    Blasco, J.; Subías, G.; García, J.; Popescu, C.; Cuartero, V.

    2015-01-15

    We report high pressure angle-dispersive x-ray diffraction measurements on Co{sub x}Fe{sub 3−x}O{sub 4} (x=1, 1.5, 1.75) spinels at room temperature up to 34 GPa. The three samples show a similar structural phase transformation from the cubic spinel structure to an analogous post-spinel phase at around 20 GPa. Spinel and post-spinel phases coexist in a wide pressure range (∼20–25 GPa) and the transformation is irreversible. The equation of state of the three cubic spinel ferrites was determined and our results agree with the data obtained in related oxide spinels showing the role of the pressure-transmitting medium for the accurate determination of the equation of state. Measurements releasing pressure revealed that the post-spinel phase is stable down to 4 GPa when it decomposes yielding a new phase with poor crystallinity. Later compression does not recover either the spinel or the post-spinel phases. This phase transformation induced by pressure explains the irreversible lost of the ferrimagnetic behavior reported in these spinels. - Graphical abstract: Pressure dependence of the unit cell volume per formula unit for Co{sub 1.5}Fe{sub 1.5}O{sub 4} spinel. Circles and squares stand for spinel and postspinel phases, respectively. Dark (open) symbols: determination upon compression (decompression). - Highlights: • The pressure induces similar phase transformation in Co{sub 3−x}Fe{sub x}O{sub 4} spinels (1≤x≤2). • The postspinel phases decompose after releasing pressure. • The irreversibility of this phase transformation explains the disappearance of magnetism in these spinels after applying pressure. • Accurate equation of state can be obtained up to 10 GPa using an alcohol mixture as pressure transmitting medium. • The equation of state suggests similar elastic properties for these spinels in this composition range.

  6. Influence of Process Parameters on Laser Weld Characteristics in Aluminum Alloys

    DTIC Science & Technology

    1988-08-01

    1 1󈧚 , 4 4 2.1.2 Alloying Element Vaporization Alloying elements added to aluminum for improving the mechanical properties and corrosion...effects the properties of the base metal surrounding the weld zone called the heat affected zone (HAZ). In the non-heat treatable aluminum alloys in the...Hydrogen in Aluminum . Magnesium, Copper, and Their Alloys . Int. Metall. Reviews, Review 201, 20:166-184. 31. Hatch, J.E. 1984. Aluminum , Properties and

  7. Magnesium and Space Flight

    PubMed Central

    Smith, Scott M.; Zwart, Sara R.

    2015-01-01

    Magnesium is an essential nutrient for muscle, cardiovascular, and bone health on Earth, and during space flight. We sought to evaluate magnesium status in 43 astronauts (34 male, 9 female; 47 ± 5 years old, mean ± SD) before, during, and after 4–6-month space missions. We also studied individuals participating in a ground analog of space flight (head-down-tilt bed rest; n = 27 (17 male, 10 female), 35 ± 7 years old). We evaluated serum concentration and 24-h urinary excretion of magnesium, along with estimates of tissue magnesium status from sublingual cells. Serum magnesium increased late in flight, while urinary magnesium excretion was higher over the course of 180-day space missions. Urinary magnesium increased during flight but decreased significantly at landing. Neither serum nor urinary magnesium changed during bed rest. For flight and bed rest, significant correlations existed between the area under the curve of serum and urinary magnesium and the change in total body bone mineral content. Tissue magnesium concentration was unchanged after flight and bed rest. Increased excretion of magnesium is likely partially from bone and partially from diet, but importantly, it does not come at the expense of muscle tissue stores. While further study is needed to better understand the implications of these findings for longer space exploration missions, magnesium homeostasis and tissue status seem well maintained during 4–6-month space missions. PMID:26670248

  8. Magnesium and Space Flight.

    PubMed

    Smith, Scott M; Zwart, Sara R

    2015-12-08

    Magnesium is an essential nutrient for muscle, cardiovascular, and bone health on Earth, and during space flight. We sought to evaluate magnesium status in 43 astronauts (34 male, 9 female; 47 ± 5 years old, mean ± SD) before, during, and after 4-6-month space missions. We also studied individuals participating in a ground analog of space flight (head-down-tilt bed rest; n = 27 (17 male, 10 female), 35 ± 7 years old). We evaluated serum concentration and 24-h urinary excretion of magnesium, along with estimates of tissue magnesium status from sublingual cells. Serum magnesium increased late in flight, while urinary magnesium excretion was higher over the course of 180-day space missions. Urinary magnesium increased during flight but decreased significantly at landing. Neither serum nor urinary magnesium changed during bed rest. For flight and bed rest, significant correlations existed between the area under the curve of serum and urinary magnesium and the change in total body bone mineral content. Tissue magnesium concentration was unchanged after flight and bed rest. Increased excretion of magnesium is likely partially from bone and partially from diet, but importantly, it does not come at the expense of muscle tissue stores. While further study is needed to better understand the implications of these findings for longer space exploration missions, magnesium homeostasis and tissue status seem well maintained during 4-6-month space missions.

  9. Enhancements in Magnesium Die Casting Impact Properties

    SciTech Connect

    David Schwam; John F. Wallace; Yulong Zhu; Srinath Viswanathan; Shafik Iskander

    2000-06-30

    The need to produce lighter components in transportation equipment is the main driver in the increasing demand for magnesium castings. In many automotive applications, components can be made of magnesium or aluminum. While being lighter, often times the magnesium parts have lower impact and fatigue properties than the aluminum. The main objective of this study was to identify potential improvements in the impact resistance of magnesium alloys. The most common magnesium alloys in automotive applications are AZ91D, AM50 and AM60. Accordingly, these alloys were selected as the main candidates for the study. Experimental quantities of these alloys were melted in an electrical furnace under a protective atmosphere comprising sulfur hexafluoride, carbon dioxide and dry air. The alloys were cast both in a permanent mold and in a UBE 315 Ton squeeze caster. Extensive evaluation of tensile, impact and fatigue properties was conducted at CWRU on permanent mold and squeeze cast test bars of AZ91, AM60 and AM50. Ultimate tensile strength values between 20ksi and 30ksi were obtained. The respective elongations varied between 25 and 115. the Charpy V-notch impact strength varied between 1.6 ft-lb and 5 ft-lb depending on the alloy and processing conditions. Preliminary bending fatigue evaluation indicates a fatigue limit of 11-12 ksi for AM50 and AM60. This is about 0.4 of the UTS, typical for these alloys. The microstructures of the cast specimens were investigated with optical and scanning electron microscopy. Concomitantly, a study of the fracture toughness in AM60 was conducted at ORNL as part of the study. The results are in line with values published in the literature and are representative of current state of the art in casting magnesium alloys. The experimental results confirm the strong relationship between aluminum content of the alloys and the mechanical properties, in particular the impact strength and the elongation. As the aluminum content increases from about 5

  10. Grosnaja ABCs: Magnesium isotope compositions

    NASA Technical Reports Server (NTRS)

    Goswami, J. N.; Srinivasan, G.; Ulyanov, A. A.

    1993-01-01

    Three CAI's from the Grosnaja CV3 chondrite were analyzed for their magnesium isotopic compositions by the ion microprobe. The selected CAI's represent three distinct types: GR4(compact Type A), GR7(Type B) and GR2(Type C). Petrographic studies indicate that all three Grosnaja inclusions were subjected to secondary alterations. The Type A CAI GR4 is primarily composed of melilite with spinel and pyroxene occurring as minor phases. The rim of the inclusion does not exhibit distinct layered structure and secondary alteration products (garnet, Fe-rich olivine and Na-rich plagioclase) are present in some localized areas near the rim region. The average major element compositions of different mineral phases in GR4 are given. Preliminary REE data suggest a depletion of HREE relative to LREE by about a factor of 3 without any clear indication of interelement fractionation. The CAI GR7 has textural and minerological characteristics similar to Type B inclusions. The REE data show a pattern that is similar to Group 6 with enrichment in Eu and Yb. In addition, a depletion of HREE compared to LREE is also evident in this object. Melilite composition shows a broad range of akermanite content (Ak(sub 15-55)). Detailed petrographic study is in progress. GR2 is a anorthite-rich Type C inclusion with large plagioclase laths intergrown with Ti-rich pyroxene. The average plagioclase composition is close to pure anorthite (An99).

  11. Cellular Magnesium Matrix Foam Composites for Mechanical Damping Applications

    NASA Astrophysics Data System (ADS)

    Shunmugasamy, Vasanth Chakravarthy; Mansoor, Bilal; Gupta, Nikhil

    2016-01-01

    The damping characteristics of metal alloys and metal matrix composites are relevant to the automotive, aerospace, and marine structures. Use of lightweight materials can help in increasing payload capacity and in decreasing fuel consumption. Lightweight composite materials possessing high damping capabilities that can be designed as structural members can greatly benefit in addressing these needs. In this context, the damping properties of lightweight metals such as aluminum and magnesium and their respective composites have been studied in the existing literature. This review focuses on analyzing the damping properties of aluminum and magnesium alloys and their cellular composites. The damping properties of various lightweight alloys and composites are compared on the basis of their density to understand the potential for weight saving in structural applications. Magnesium alloys are observed to possess better damping properties in comparison to aluminum. However, aluminum matrix syntactic foams reinforced with silicon carbide hollow particles possess a damping capacity and density comparable to magnesium alloy. By using the data presented in the study, composites with specific compositions and properties can be selected for a given application. In addition, the comparison of the results helps in identifying the areas where attention needs to be focused to address the future needs.

  12. Aluminum Target Dissolution in Support of the Pu-238 Program

    SciTech Connect

    McFarlane, Joanna; Benker, Dennis; DePaoli, David W; Felker, Leslie Kevin; Mattus, Catherine H

    2014-09-01

    Selection of an aluminum alloy for target cladding affects post-irradiation target dissolution and separations. Recent tests with aluminum alloy 6061 yielded greater than expected precipitation in the caustic dissolution step, forming up to 10 wt.% solids of aluminum hydroxides and aluminosilicates. We present a study to maximize dissolution of aluminum metal alloy, along with silicon, magnesium, and copper impurities, through control of temperature, the rate of reagent addition, and incubation time. Aluminum phase transformations have been identified as a function of time and temperature, using X-ray diffraction. Solutions have been analyzed using wet chemical methods and X-ray fluorescence. These data have been compared with published calculations of aluminum phase diagrams. Temperature logging during the transients has been investigated as a means to generate kinetic and mass transport data on the dissolution process. Approaches are given to enhance the dissolution of aluminum and aluminosilicate phases in caustic solution.

  13. Effect of Heat-Treatment and Composition on Structure and Luminescence Properties of Spinel-Type Solid Solution Nanocrystals.

    PubMed

    Sakoda, Kazuki; Hirano, Masanori

    2015-08-01

    The compositional dependence of the structure and properties of spinel-type solid solutions, Zn(A,Ga)2O4 was investigated by comparison with samples hydrothermally prepared and those after heat treatment at 1000 °C in air. Nanocrystalline spinel-type solid solutions in the whole composition range in the ZnAl2O4-ZnGa2O4 system were directly formed from the aqueous precursor solutions of ZnSO4, Al(NO3)3 and Ga(NO3)3 under hydrothermal conditions at 180 °C for 5 h in the presence of tetramethylammonium hydroxide. The incorporation of aluminum into the lattice, Zn(AlxGa1-x)2O4, resulted in lower crystallinity of the spinel. The relationship between the lattice parameter of as-prepared samples and the Al atomic ratio in the spinel composition was slightly apart from the ideal linear relationship that was obtained in the samples after heat treatment at 1000 °C. The optical band gap of both as-prepared solid solutions and those heat treated linearly increased from 4.1~4.2 to 5.25 eV by the incorporation of aluminum ion into the lattice, Zn(AlxGa1-x)2O4. Two main broad-band emission spectra centered at around 360 and 430 nm in the range of 300-600 nm were observed in the spinel solid solutions under excitation at 270 nm, thought their broad-band emission spectra and their peak wavelengths subtly changed depending on the composition and heat treatment.

  14. High magnetization limits of spinel ferrite

    NASA Astrophysics Data System (ADS)

    Dionne, Gerald F.

    1987-04-01

    Modifications to a previously reported theoretical model of the thermomagnetization properties of LiZnTi spinel ferrite have made possible the prediction of upper limits to the magnetization of the spinel system. Extrapolation of the molecular-field coefficient relations to the limits of the undiluted spinel, i.e., the fictitious case of unrestricted Fe3+ occupancy, provides a basis for computing all combinations of dilutant site distributions. For this situation, the maximum room-temperature magnetization and Curie temperature approach 8000 G and 1050 K, respectively. Computations for the more realistic monovalent cation system Fe3+1-xA1+x [B1+0.5-xFe3+1.5+x]O4, where A and B could represent any combination of Li, Na, or possibly Cu, yield an optimum magnetization that could reach 6500 G with a Curie temperature of about 700 K. In the context of this theoretical model, the cation site distributions for high magnetization in the Mn and Ni spinel ferrite families are also discussed.

  15. The design research of a spinel dome

    NASA Astrophysics Data System (ADS)

    Zhao, Hongwei; Hou, Tianjin; Zhu, Bin; Huang, Qiu; Gao, Zhifeng

    2011-08-01

    Based on the aerodynamic heating simulated results of a spinel middle-infrared (Mid IR) image guide missile dome flying at supersonic speed, a series of experiments are made and some methods of eliminating aero-heating effect are carried out successfully. First, a simulation experiment on the ground discarding an outside protective shell of a spinel dome is accomplished in order to inspect the withstanding impact ability of the dome. Second, an arc wind tunnel experiment is fulfilled to obtain thermal mechanics characteristic of the spinel dome, and a method to buildup obviously mechanics intensity is approved which is coating diamond protective layer on the external wall of the spinel dome. Third, two heated dome imaging experiments on the ground are made to study the aero-optical phenomenon. Finally, a rocket sled experiment of a guide missile head is made successfully. Experimental results show that when the guide missile head flies in a supersonic, by adjusting the frame integration time of detector etc. the aero-optic effect would decrease greatly.

  16. Dopants and defects in conductive oxide spinels

    NASA Astrophysics Data System (ADS)

    Zakutayev, Andriy; Perkins, John; Parilla, Phillip; Paudel, Tula; Lany, Staphan; Ginely, David; Zunger, Alex

    2011-03-01

    We will discuss the effects of extrinsic and intrinsic imperfections (dopants and defects) in a group of conductive oxide materials related to Co3O4. Co3O4 is a spinel with Co2+ and Co3+ on tetrahedral and octahedral sites, respectively. Doping of Co3O4 with Zn and Ni represent two limiting cases: Zn2+ ions have a preference to occupy tetrahedral (Co2+) sites and are predicted to be unable to dope effectively; Ni2+ ions have a preference to occupy octahedral (Co3+) sites, so these atoms are expected to be efficient dopants. We found that substitution of Co3O4 spinel with up to 33 percent of Zn and Ni results in formation of ZnCo2O4 normal spinel and NiCo2O4 inverse spinel, and causes 100-fold and 1000-fold increases in conductivity, respectively, matching the predicted trend. Increase in Zn and Ni concentraion up to 40 percent cause phase separation of ZnO and NiO and leveling out of the conductivity. The conductivity decreases sharply above 50-60 percent Zn and Ni substitution level. Small differences with the theoretical predictions may be explained by non-equilibrium character of the thin film deposition process. This work was supported by the ``Center for Inverse Design'' EFRC of the Department of Energy.

  17. Aluminum Analysis.

    ERIC Educational Resources Information Center

    Sumrall, William J.

    1998-01-01

    Presents three problems based on the price of aluminum designed to encourage students to be cooperative and to use an investigative approach to learning. Students collect and synthesize information, analyze results, and draw conclusions. (AIM)

  18. Reaction temperature variations on the crystallographic state of spinel cobalt aluminate.

    PubMed

    Taguchi, Minori; Nakane, Takayuki; Hashi, Kenjiro; Ohki, Shinobu; Shimizu, Tadashi; Sakka, Yoshio; Matsushita, Akiyuki; Abe, Hiroya; Funazukuri, Toshitaka; Naka, Takashi

    2013-05-21

    In this study, we report a rapid and simple technique for obtaining cobalt aluminate having a spinel structure. The products were prepared from a hydroxide precursor synthesized by coprecipitation of cobalt (Co(2+)) and aluminum (Al(3+)) nitrates with an alkaline solution. The chosen precursor enabled low temperature fabrication of cobalt aluminate with a spinel structure by sintering it for 2 hours at low temperatures (>400 °C). Crystallographic and thermal analyses suggest that the low-temperature-sintered products contain Co(3+) ions stabilized by chemisorbed water and/or hydroxide groups, which was not observed for products sintered at temperatures higher than 1000 °C. The color of the products turned from clear blue (Thenard's blue) to dark green when sintering temperatures were below 1000 °C. Magnetic quantities, Curie constants, and Weiss temperatures show a strong dependence on the sintering temperature. These findings suggest that there are mixed valent states, i.e. Co(2+) and Co(3+), and unique cation distributions at the different crystallographic sites in the spinel structure, especially in the products sintered at lower temperatures.

  19. A thermodynamic model of Fe Cr spinels

    NASA Astrophysics Data System (ADS)

    Kurepin, Viktor A.

    2005-07-01

    A new thermodynamic model for multi-component spinel solid solutions has been developed which takes into account thermodynamic consequences of cation mixing in spinel sublattices. It has been applied to the evaluation of thermodynamic functions of cation mixing and thermodynamic properties of Fe3O4 FeCr2O4 spinels using intracrystalline cation distribution in magnetite, lattice parameters and activity-composition relations of magnetite chromite solid solutions. According to the model, cation distribution in binary spinels, (Fe1-x2+ Fex3+)[Fex2+Fe2-2y-x3+Cr2y]O4, and their thermodynamic properties depend strongly on Fe2+ Cr3+ cation mixing. Mixing of Fe2+ Fe3+ and Fe3+ Cr3+ can be accepted as ideal. If Fe2+, Fe3+ and Cr are denoted as 1, 3 and 4 respectively, the equation of cation distribution is -RT ln(x2/((1-x)(2-2y-x)))= ΔG13* + (1-2x)W13+y(W14-W13-W34) where ΔG13* is the difference between the Gibbs energy of inverse and normal magnetite, Wij is a Margules parameter of cation mixing and ΔG13*, J/mol =-23,000+13.4 T, W14=36 kJ/mol, W13=W34=0. The positive nonconfigurational Gibbs energy of mixing is the main reason for changing activity composition relations with temperature. According to the model, the solvus in Fe3O4 FeCr2O4 spinel has a critical temperature close to 500°C, which is consistent with mineralogical data.

  20. Distinction of gem spinels from the himalayan mountain belt.

    PubMed

    Malsy, Anna; Klemmb, Leonhard

    2010-01-01

    Gem spinel deposits in Myanmar, Vietnam and Tajikistan have their formation in association with Himalayan orogenesis. Gem-quality orange, pink, red and purple spinels from deposits at Mogok (Myanmar), Luc Yen (Vietnam), and Kuh-i-Lal (Tajikistan) have been investigated by 'standard' gemological testing and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Microscopic examination yielded apatite and calcite inclusions together with octahedral negative crystals to be most frequently present in Mogok spinels. The presence of dislocation systems and titanite inclusions are indicative inclusion features for spinels from Luc Yen. Trace elements such as Ti, Fe, Ni, Zn, Zr and Sn differ slightly in spinels from the sources investigated. A distinction of spinels from these deposits is therefore possible by trace element chemistry. This is especially helpful for gem spinels, which often show few inclusions or completely lack inclusion features.

  1. Magnesium ferrite nanoparticles: a rapid gas sensor for alcohol

    NASA Astrophysics Data System (ADS)

    Godbole, Rhushikesh; Rao, Pratibha; Bhagwat, Sunita

    2017-02-01

    Highly porous spinel MgFe2O4 nanoparticles with a high specific surface area have been successfully synthesized by a sintering free auto-combustion technique and characterized for their structural and surface morphological properties using XRD, BET, TEM and SEM techniques. Their sensing properties to alcohol vapors viz. ethanol and methanol were investigated. The site occupation of metal ions was investigated by VSM. The as-synthesized sample shows the formation of sponge-like porous material which is necessary for gas adsorption. The gas sensing characteristics were obtained by measuring the gas response as a function of operating temperature, concentration of the gas, and the response-recovery time. The response of magnesium ferrite to ethanol and methanol vapors was compared and it was revealed that magnesium ferrite is more sensitive and selective to ethanol vapor. The sensor operates at a substantially low vapor concentration of about 1 ppm of alcohol vapors, exhibits fantastic response reproducibility, long term reliability and a very fast response and recovery property. Thus the present study explored the possibility of making rapidly responding alcohol vapor sensor based on magnesium ferrite. The sensing mechanism has been discussed in co-relation with magnetic and morphological properties. The role of occupancy of Mg2+ ions in magnesium ferrite on its gas sensing properties has also been studied and is found to influence the response of magnesium ferrite ethanol sensor.

  2. Electrical and magnetic properties of nano-sized magnesium ferrite

    NASA Astrophysics Data System (ADS)

    T, Smitha; X, Sheena; J, Binu P.; Mohammed, E. M.

    2015-02-01

    Nano-sized magnesium ferrite was synthesized using sol-gel techniques. Structural characterization was done using X-ray diffractometer and Fourier Transform Infrared Spectrometer. Vibration Sample Magnetometer was used to record the magnetic measurements. XRD analysis reveals the prepared sample is single phasic without any impurity. Particle size calculation shows the average crystallite size of the sample is 19nm. FTIR analysis confirmed spinel structure of the prepared samples. Magnetic measurement study shows that the sample is ferromagnetic with high degree of isotropy. Hysterisis loop was traced at temperatures 100K and 300K. DC electrical resistivity measurements show semiconducting nature of the sample.

  3. Aluminum alloy welding and stress-corrosion testing. Final report

    SciTech Connect

    Gates, W.G.; Jimenez, E.

    1981-04-01

    The weldability, strength, and corrosion resistance of four 5XXX aluminum alloys electron beam welded to 6061-T6 aluminum alloy without a filler metal were evaluated. Adding filler metal raises weld energy requirements and makes the process more difficult to control. In this study, instead of using a filler metal, a high-magnesium 5XXX alloy was welded to the 6061 alloy. The four 5XXX alloys used (5456-H321, 5052-H34, 5086-H323, and 5083-H32) were selected for their high magnesium content which reduces weld crack sensitivity.

  4. Effect of Roll Material on Surface Quality of Rolled Aluminum

    NASA Astrophysics Data System (ADS)

    Zhao, Qi

    The surface defects of aluminum alloys that have undergone hot rolling were studied. The effects of different roll materials, of the number of rolling passes and of lubrication on surface defects of hot rolled aluminum alloys were investigated by laboratory hot rolling. Two different aluminum alloys, Al-Mn and Al-Mg, were each rolled against three different steel alloy rolls, AISI 52100, AISI 440C and AISI D2. The results showed that different roll materials do affect the morphology of the mating aluminum alloy surface with apparent surface defects, which included magnesium and oxygen rich dark regions on both alloys. The carbide protrusions in 440C and D2 steel rolls are confirmed to be responsible for the dark, rich magnesium and oxygen regions on both the rolled Al-Mn and Al-Mg alloy surfaces. As the number of passes increases, Mg and O deposit in the form of patches and grain boundaries near the surface area.

  5. Aluminum alloy

    NASA Technical Reports Server (NTRS)

    Blackburn, Linda B. (Inventor); Starke, Edgar A., Jr. (Inventor)

    1989-01-01

    This invention relates to aluminum alloys, particularly to aluminum-copper-lithium alloys containing at least about 0.1 percent by weight of indium as an essential component, which are suitable for applications in aircraft and aerospace vehicles. At least about 0.1 percent by weight of indium is added as an essential component to an alloy which precipitates a T1 phase (Al2CuLi). This addition enhances the nucleation of the precipitate T1 phase, producing a microstructure which provides excellent strength as indicated by Rockwell hardness values and confirmed by standard tensile tests.

  6. Spinel: gaining momentum in optical applications

    NASA Astrophysics Data System (ADS)

    Patterson, Mark C. L.; DiGiovanni, Anthony A.; Fehrenbacher, Lawrence; Roy, Don W.

    2003-09-01

    There are presently three materials (sapphire, ALON and spinel) which exhibit a desirable combination of material properties such as hardness, strength, and transmission in MWIR that are considered for various window/dome applications. Of the three, sapphire exists in a number of service applications. It is, however, the most expensive of the three and depending on application, can have significant drawbacks owing to its birefringent nature. ALON, by comparison is less expensive, benefits from greater development efforts, is an easily shaped polycrystalline ceramic, optically does not possess the birefringent nature of sapphire, but requires very high formation temperatures for the starting powders and equally long processing times for fabricated parts. The remaining material, transparent spinel, offers improved optical performance over the spectrum from UV to MWIR, comparable mechanical properties, and can be fabricated at much lower temperatures and shorter times than the other materials making it less expensive to produce. Data will be described which compares the transparency and mechanical properties and discusses the relevant processing efforts for spinel products.

  7. Micro-XANES Measurements on Experimental Spinels and the Oxidation State of Vanadium in Spinel-Melt Pairs

    NASA Technical Reports Server (NTRS)

    Righter, K.; Sutton, S.R.; Newville, M.

    2004-01-01

    Spinel can be a significant host phase for V as well as other transition metals such as Ni and Co. However, vanadium has multiple oxidation states V(2+), V(3+), V(4+) or V(5+) at oxygen fugacities relevant to natural systems. We do know that D(V) spinel/melt is correlated with V and TiO2 content and fO2, but the uncertainty of the oxidation state under the range of natural conditions has made elusive a thorough understanding of D(V) spinel/melt. For example, V(3+) is likely to be stable in spinels, based on exchange with Al in experiments in the CaO-MgO-Al2O3-SiO2 system. On the other hand, it has been argued that V(4+) will be stable across the range of natural oxygen fugacities in nature. In order to gain a better understanding of D(V) spinel/melt we have equilibrated spinel-melt pairs at controlled oxygen fugacities, between HM to NNO, where V is present in the spinel at natural levels (approx. 300 ppm V). These spinel-melt pairs were analyzed using micro-XANES at the Advanced Photon Source at Argonne National Laboratory. The new results will be used together with spinel compositional data (Ti, V content) and oxygen fugacity, to unravel the effects of these variables on D(V) spinel/melt.

  8. Comparison of hot-pressing, rate-controlled sintering, and microwave sintering of magnesium aluminate for optical applications

    NASA Astrophysics Data System (ADS)

    Gilde, Gary A.; Patel, Parimal J.; Patterson, Mark

    1999-07-01

    There are several crystalline materials that transmit electromagnetic radiation in the visible and IR portion of the spectrum. At this time, single-crystal sapphire, aluminum oxynitride (ALON), and spinel show promise for applications, including advanced electromagnetic windows and transparent armor. These applications require materials with high strength, hardness, and the ability to withstand high temperatures. Because of lower processing temperatures and shorter processing times, it is reasonable to assume that spinel should ultimately be less costly to produce than ALON or sapphire. Despite many attempts to commercialize spinel, it is not available today as an optical materials due to difficulties in reliably obtaining the desired transparently. To help develop a commercial source for transparent spinel, the US Army Research Laboratory and Ceramic Composites Inc. of Annapolis have signed a Cooperative Research and Development Agreement on the 'Development and Dual-Use Assessment of Transparent Spinel'. The advent of commercially available, highly pure spinel powders should lead to improvements in processing spinel to transparency. This investigation compares the advantages and limitations of hot-pressing, microwave sintering, and rate- controlled sintering and compares the limited property data available from each of these fabrication techniques.

  9. Aluminum phosphide

    Integrated Risk Information System (IRIS)

    Aluminum phosphide ; CASRN 20859 - 73 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinoge

  10. Combustion Synthesis of Magnesium Aluminate

    SciTech Connect

    Kale, M. A.; Joshi, C. P.; Moharil, S. V.

    2011-10-20

    In the system MgO-Al{sub 2}O{sub 3}, three compounds MgAl{sub 2}O{sub 4}, MgAl{sub 6}O{sub 10}(also expressed as-Mg{sub 0.4}Al{sub 2.4}O{sub 4}) and MgAl{sub 26}O{sub 40} are well known. Importance of the first two is well established. Magnesium aluminate (MgAl{sub 2}O{sub 4}) spinel is a technologically important material due to its interesting thermal properties. The MgAl{sub 2}O{sub 4} ceramics also find application as humidity sensors. Apart from the luminescence studies, the interest in MgAl{sub 2}O{sub 4} is due to various applications such as humidity-sensing and PEM fuel cells, TL/OSL dosimetry of the ionizing radiations, white light source. Interest in the MgAl{sub 6}O{sub 10} has aroused due to possible use as a substrate for GaN growth. Attempt was made to synthesize these compounds by the combustion synthesis using metal nitrates as oxidizer and urea as a fuel. Compounds MgAl{sub 2}O{sub 4} and MgAl{sub 6}O{sub 10} were formed in a single step, while MgAl{sub 26}O{sub 40} was not formed by this procedure. Activation of MgAl{sub 6}O{sub 10} by rare earth ions like Ce{sup 3+}, Eu{sup 3+} and Tb{sup 3+} and ns{sup 2} ion Pb{sup 2+} could be achieved. Excitation bands for MgAl{sub 6}O{sub 10} are at slightly shorter wavelengths compared to those reported for MgAl{sub 2}O{sub 4}.

  11. Isotopically uniform, 16O-depleted calcium, aluminum-rich inclusions in CH and CB carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Krot, Alexander N.; Nagashima, Kazuhide; Petaev, Michail I.

    2012-04-01

    In situ oxygen-isotope measurements of calcium-aluminum-rich inclusions (CAIs) from the metal-rich carbonaceous chondrites Isheyevo (CH/CB-like), Acfer 214 paired with Acfer 182 (CH), QUE 94411 paired with QUE 94627 (CBb), and Hammadah al Hamra 237 (CBb) revealed the presence of a common population of igneous, isotopically uniform, 16O-depleted inclusions: Δ17O (average ± 2 standard deviations) = -7 ± 4‰, -6 ± 5‰, and -8 ± 3‰, respectively. All CAIs from CBs and a significant fraction of those from CHs and Isheyevo are 16O-depleted. Most of the 16O-depleted CAIs consist of Ti-poor Al-diopside, spinel, melilite, and forsterite and surrounded by a single- and double-layered rim of forsterite ± diopside. The 16O-depleted CAIs composed of hibonite, grossite, melilite, and spinel, and surrounded by the multilayered melilite + diopside ± forsterite rims are less common. Some of the 16O-depleted refractory igneous inclusions composed of Al-diopside, forsterite, and ±spinel have chondrule-like textures (skeletal or barred). They are mineralogically most similar to Al-diopside-rich chondrules found in metal-rich carbonaceous chondrites and composed of Al-diopside, forsterite, Al-rich low-Ca pyroxene, ±glassy mesostasis, and ±spinel, suggesting there is a continuum between these objects. We suggest that (i) most of the isotopically uniform and 16O-depleted CAIs resulted from remelting of pre-existing, possibly 16O-rich refractory inclusions. The remelting may have occurred during formation of the magnesian, non-porphyritic (cryptocrystalline and skeletal) chondrules in CHs, CBs, and Isheyevo either by an unspecified, late, single-stage, highly-energetic event or in an impact-generated plume previously hypothesized for their origin; both mechanisms probably occurred in the solar nebula (i.e., in the presence of the nebula gas). The forsterite ± pyroxene rims around 16O-depleted CAIs may have resulted from evaporation-recondensation of silicon and magnesium

  12. WETTING AND BONDING BETWEEN ALUMINUM ALLOYS AND SAPPHIRE.

    DTIC Science & Technology

    equilibrium contact angle ; the lowest contact angle observed was 94 degrees and was obtained with 0.94 atomic percent addition of magnesium to pure aluminum...The contact angle was not affected by additions of lead, vanadium, manganese, chromium, and bismuth, whereas it was increased by additions of

  13. Method for production of magnesium

    DOEpatents

    Diaz, A.F.; Howard, J.B.; Modestino, A.J.; Peters, W.A.

    1998-07-21

    A continuous process for the production of elemental magnesium is described. Magnesium is made from magnesium oxide and a light hydrocarbon gas. In the process, a feed stream of the magnesium oxide and gas is continuously fed into a reaction zone. There the magnesium oxide and gas are reacted at a temperature of about 1400 C or greater in the reaction zone to provide a continuous product stream of reaction products, which include elemental magnesium. The product stream is continuously quenched after leaving the reaction zone, and the elemental magnesium is separated from other reaction products. 12 figs.

  14. Method for production of magnesium

    DOEpatents

    Diaz, Alexander F.; Howard, Jack B.; Modestino, Anthony J.; Peters, William A.

    1998-01-01

    A continuous process for the production of elemental magnesium is described. Magnesium is made from magnesium oxide and a light hydrocarbon gas. In the process, a feed stream of the magnesium oxide and gas is continuously fed into a reaction zone. There the magnesium oxide and gas are reacted at a temperature of about 1400.degree. C. or greater in the reaction zone to provide a continuous product stream of reaction products, which include elemental magnesium. The product stream is continuously quenched after leaving the reaction zone, and the elemental magnesium is separated from other reaction products.

  15. Modification of Alumina and Spinel Inclusions by Calcium in Liquid Steel

    NASA Astrophysics Data System (ADS)

    Verma, Neerav

    2011-12-01

    samples were characterized for inclusion shape, size and chemistry through scanning electron microscopy (SEM). Automated inclusion analysis tools (like ASCAT [59, 91, 92], INCA-GSR [126]; Please refer section 6.4., page number 68) were employed to generate statistical information of the inclusions. Thermodynamic database software FACTSAGE [62] was used to determine thermochemistry of reactions, ternary phase diagrams (Ca-Al-S and Ca-Al-Mg systems). The compositions of the inclusions were tracked before and after calcium treatment to determine the effectiveness of calcium treatment. Extraction of inclusions through dissolution of iron in bromine-methanol solution was employed to reveal 3-D geometry of inclusions and analyze inclusions through EDS (Energy-dispersive X-ray spectroscopy) without any matrix effects. Various industrial samples were also analyzed to confirm the feasibility of various reaction mechanisms deduced through experiments. Successful modification of alumina and spinel inclusions by calcium was demonstrated [85, 86]. It was observed that these modification mechanisms proceed through transient phase (CaO, CaS) formation. In the case of spinels, preferential reduction of MgO part was also observed during calcium modification of spinels. The magnesium after MgO reduction by calcium can enter back into the melt or leave the melt in vapor form. The inclusion area fraction decreased after calcium treatment, but the inclusion concentration (number of inclusions per cm2) increased because inclusions shifted to a smaller size distribution after calcium treatment. Severe matrix effects during EDS analysis of inclusions were observed, due to which inclusion composition analyses can be significantly affected. *Please refer to dissertation for footnotes.

  16. Magnesium battery disposal characteristics

    NASA Astrophysics Data System (ADS)

    Soffer, Louis; Atwater, Terrill

    1994-12-01

    This study assesses the disposal characteristics of U.S. Army procured military magnesium batteries under current Resource Conservation and Recovery Act (RCRA) hazardous waste identification regulations administered by the U.S. Environmental Protection Agency. Magnesium batteries were tested at 100, 50, 10 and 0 percent remaining state of charge. Present findings indicate that magnesium batteries with less than 50 percent remaining charge do not exceed the federal regulatory limit of 5.0 mg/L for chromium. All other RCRA contaminates were below regulatory limits at all levels of remaining charge. Assay methods, findings, disposal requirements and design implications are discussed.

  17. Magnesium toxicosis in two horses.

    PubMed

    Henninger, R W; Horst, J

    1997-07-01

    Magnesium sulfate, a saline laxative, is often used for treatment of intestinal impactions in horses. Clinical signs of hypermagnesemia are an uncommon complication following oral administration of magnesium sulfate. Overdose of magnesium sulfate in combination with renal insufficiency, hypocalcemia, or compromise of intestinal integrity may predispose horses to magnesium toxicosis. Establishment of diuresis with fluids and IV administration of calcium may provide successful treatment of magnesium toxicosis in horses.

  18. Studies of aluminum in rat brain

    SciTech Connect

    Lipman, J.J.; Brill, A.B.; Som, P.; Jones, K.W.; Colowick, S.; Cholewa, M.

    1985-01-01

    The effects of high aluminum concentrations in rat brains were studied using /sup 14/C autoradiography to measure the uptake of /sup 14/C 2-deoxy-D-glucose (/sup 14/C-2DG) and microbeam proton-induced x-ray emission (microPIXE) with a 20-..mu..m resolution to measure concentrations of magnesium, aluminum, potassium, and calcium. The aluminum was introduced intracisternally in the form of aluminum tartrate (Al-T) while control animals were given sodium tartrate (Na-T). The /sup 14/C was administered intravenously. The animals receiving Al-T developed seizure disorders and had pathological changes that included cerebral cortical atrophy. The results showed that there was a decreased uptake of /sup 14/C-2DG in cortical regions in which increased aluminum levels were measured, i.e., there is a correlation between the aluminum in the rat brain and decreased brain glucose metabolism. A minimum detection limit of about 16 ppM (mass fraction) or 3 x 10/sup 9/ Al atoms was obtained for Al under the conditions employed. 14 refs., 4 figs., 1 tab.

  19. Chromium crystal chemistry mullite-spinel refractory ceramics

    SciTech Connect

    Levy, D.; Gualtieri, A.; Quartieri, S.; Artioli, G.; Valle, M.

    1999-03-15

    A small amount of chromium oxide was added to a mullite-spinel refractory mixture to improve its thermal and mechanical properties. Two different compositions of mullite-spinel refractory were studied to define the crystal structures hosting the chromium cations, and the chromium solubility in spinel (MgAl{sub 2{minus}x}Cr{sub x}O{sub 4}) was determined. Powder X-ray diffraction (XRD), X-ray absorption near edge spectroscopy (XANES), and scanning electron microscopy (SEM) elemental distribution maps were used to determine the chromium crystal chemistry in the system. The observed maximum solubility of chromium in spinel was found at x = 1.2, but the presence of mullite in the mixture caused a strong decrease of this value. The chromium distribution among the crystal phases reflects the different reaction paths of the two samples: a stage involving spinel and melt drives all present chromium in the spinel, while a simultaneous crystallization of spinel-mullite distributes chromium cations between mullite, spinel, and secondary corundum.

  20. High Strength Aluminum Alloy For High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A. (Inventor); Chen, Po-Shou (Inventor)

    2005-01-01

    A cast article from an aluminum alloy has improved mechanical properties at elevated temperatures. The cast article has the following composition in weight percent: Silicon 6.0-25.0, Copper 5.0-8.0, Iron 0.05-1.2, Magnesium 0.5-1.5, Nickel 0.05-0.9, Manganese 0.05-1.2, Titanium 0.05-1.2, Zirconium 0.05-1.2, Vanadium 0.05-1.2, Zinc 0.05-0.9, Strontium 0.001-0.1, Phosphorus 0.001-0.1, and the balance is Aluminum, wherein the silicon-to-magnesium ratio is 10-25, and the copper-to-magnesium ratio is 4-15. The aluminum alloy contains a simultaneous dispersion of three types of Al3X compound particles (X=Ti, V, Zr) having a LI2 crystal structure, and their lattice parameters are coherent to the aluminum matrix lattice. A process for producing this cast article is also disclosed, as well as a metal matrix composite, which includes the aluminum alloy serving as a matrix containing up to about 60% by volume of a secondary filler material.

  1. Magnesium blood test

    MedlinePlus

    Magnesium - blood ... A blood sample is needed. ... When the needle is inserted to draw blood, some people feel slight pain. Others feel a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon ...

  2. Interstellar magnesium abundances

    NASA Technical Reports Server (NTRS)

    Murray, M. J.; Dufton, P. L.; Hibbert, A.; York, D. G.

    1984-01-01

    An improved evaluation of the Mg II 1240 A doublet oscillator strength is used in conjunction with recently published Copernicus observations to derive accurate Mg II column densities toward 74 stars. These imply an average of 40 percent of interstellar magnesium is in the gaseous phase. Magnesium depletion is examined as a function of various interstellar extinction and density parameters, and the results are briefly discussed in terms of current depletion theories.

  3. Rechargeable Magnesium Power Cells

    NASA Technical Reports Server (NTRS)

    Koch, Victor R.; Nanjundiah, Chenniah; Orsini, Michael

    1995-01-01

    Rechargeable power cells based on magnesium anodes developed as safer alternatives to high-energy-density cells like those based on lithium and sodium anodes. At cost of some reduction in energy density, magnesium-based cells safer because less susceptible to catastrophic meltdown followed by flames and venting of toxic fumes. Other advantages include ease of handling, machining, and disposal, and relatively low cost.

  4. Corrosion Resistant Magnesium-Based Materials for Naval Applications

    DTIC Science & Technology

    1985-04-01

    MARINE ATMOSPHERE AT NSWC, FT. LAUDERDALE, FLORIDA,. CORROSION TEST FACILITY .................... 13 5 PHASE DIAGRAMS OF MAGNESIUM- BERYLLIUM AND...aluminum components (p a 2.7 g/cc) must possess measurably better physical properties and comparable workability. Beryllium (p - 1.85 g/cc) was...dedicated special fabrication facilities are required for working with Beryllium because of its extreme toxicity it. handling and machining. The next

  5. Characterization of salt cake from secondary aluminum production.

    PubMed

    Huang, Xiao-Lan; Badawy, Amro El; Arambewela, Mahendranath; Ford, Robert; Barlaz, Morton; Tolaymat, Thabet

    2014-05-30

    Salt cake is a major waste component generated from the recycling of secondary aluminum processing (SAP) waste. Worldwide, the aluminum industry produces nearly 5 million tons of waste annually and the end-of-life management of these wastes is becoming a challenge in the U.S. and elsewhere. In this study, the mineral phases, metal content and metal leachability of 39 SAP waste salt cake samples collected from 10 different facilities across the U.S. were determined. The results showed that aluminum (Al), aluminum oxide, aluminum nitride and its oxides, spinel and elpasolite are the dominant aluminum mineral phases in salt cake. The average total Al content was 14% (w/w). The overall percentage of the total leachable Al in salt cake was 0.6% with approximately 80% of the samples leaching at a level less than 1% of the total aluminum content. The extracted trace metal concentrations in deionized water were relatively low (μgL(-1) level). The toxicity characteristic leaching procedure (TCLP) was employed to further evaluate leachability and the results indicated that the leached concentrations of toxic metals from salt cake were much lower than the EPA toxicity limit set by USEPA.

  6. Magnesium recycling in the United States in 1998

    USGS Publications Warehouse

    Kramer, Deborah A.

    2001-01-01

    As concern for the environment has grown in recent years, the importance of recycling has become more evident. The more materials that are recycled, the fewer natural resources will be consumed and the fewer waste products will end up in landfills, in the water, and in the air. As one of a series of reports on metals recycling, this report discusses the 1998 flow of magnesium from extraction through its uses with particular emphasis on recycling. In 1998, the recycling rate for magnesium was estimated to be 33 percent?almost 60 percent of the magnesium that was recycled came from new scrap, primarily waste from diecasting operations. The principal source of old scrap was recycled aluminum beverage cans.

  7. Magnesium recycling in the United States in 1998

    USGS Publications Warehouse

    Kramer, Deborah A.

    2002-01-01

    As concern for the environment has grown in recent years, the importance of recycling has become more evident. The more materials that are recycled, the fewer natural resources will be consumed and the fewer waste products will end up in landfills, the water, and the air. As one of a series of reports on metals recycling, this report discusses the 1998 flow of magnesium in the United States from extraction through its uses with particular emphasis on recycling. In 1998, the recycling efficiency for magnesium was estimated to be 33 percent--almost 60 percent of the magnesium that was recycled came from new scrap, primarily waste from die-casting operations. The principal source of old scrap was recycled aluminum beverage cans.

  8. High Velocity Forming of Magnesium and Titanium Sheets

    SciTech Connect

    Revuelta, A.; Larkiola, J.; Korhonen, A. S.; Kanervo, K.

    2007-04-07

    Cold forming of magnesium and titanium is difficult due to their hexagonal crystal structure and limited number of available slip systems. However, high velocity deformation can be quite effective in increasing the forming limits. In this study, electromagnetic forming (EMF) of thin AZ31B-O magnesium and CP grade 1 titanium sheets were compared with normal deep drawing. Same dies were used in both forming processes. Finite element (FE) simulations were carried out to improve the EMF process parameters. Constitutive data was determined using Split Hopkinson Pressure Bar tests (SHPB). To study formability, sample sheets were electromagnetically launched to the female die, using a flat spiral electromagnetic coil and aluminum driver sheets. Deep drawing tests were made by a laboratory press-machine.Results show that high velocity forming processes increase the formability of Magnesium and Titanium sheets although process parameters have to be carefully tuned to obtain good results.

  9. On the Modeling of Plastic Deformation of Magnesium Alloys

    SciTech Connect

    Ertuerk, S.; Steglich, D.; Bohlen, J.; Letzig, D.; Brocks, W.

    2007-05-17

    Magnesium alloys are promising materials due to their low density and therefore high specific strength. However, the industrial application is not well established so far, especially for wrought products such as sheets or profiles. Due to its hexagonal crystallographic structure, deformation mechanisms observed in magnesium alloys are rather different from those in face centered cubic metals such as aluminum alloys. This leads not only to a mechanical anisotropy, but also to a tension-compression asymmetry, i.e. unequal compressive and tensile yield strength. The resulting complexity in the yielding behavior of such materials cannot be captured by conventional models of J2 plasticity. Cazacu and Barlat, therefore, proposed a phenomenological yield potential which accounts for the respective phenomena by introducing the third invariant of the stress tensor. Simulations based on this model are performed with ABAQUS/Explicit and a user defined routine VUMAT for validating the respective implementation. The application aims at simulating the extrusion process of magnesium alloys.

  10. On the Modeling of Plastic Deformation of Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Ertürk, S.; Steglich, D.; Bohlen, J.; Letzig, D.; Brocks, W.

    2007-05-01

    Magnesium alloys are promising materials due to their low density and therefore high specific strength. However, the industrial application is not well established so far, especially for wrought products such as sheets or profiles. Due to its hexagonal crystallographic structure, deformation mechanisms observed in magnesium alloys are rather different from those in face centered cubic metals such as aluminum alloys. This leads not only to a mechanical anisotropy, but also to a tension-compression asymmetry, i.e. unequal compressive and tensile yield strength. The resulting complexity in the yielding behavior of such materials cannot be captured by conventional models of J2 plasticity. Cazacu and Barlat, therefore, proposed a phenomenological yield potential which accounts for the respective phenomena by introducing the third invariant of the stress tensor. Simulations based on this model are performed with ABAQUS/Explicit and a user defined routine VUMAT for validating the respective implementation. The application aims at simulating the extrusion process of magnesium alloys.

  11. Magnesium for Future Autos

    SciTech Connect

    Nyberg, Eric A.; Luo, Alan A.; Sadayappan, Kumar; Shi, Wenfang

    2008-10-01

    In the quest for better fuel economy and improved environmental performance, magnesium may well become a metal of choice for constructing lighter, more efficient vehicles. Magnesium is the lightest structural metal, yet it has a high strength-to-weight ratio makes it comparable to steel in many applications. The world’s automakers already use magnesium for individual components. But new alloys and processing methods are needed before the metal can become economically and technologically feasible as a major automotive structural material. This article will explore the formation, challenges and initial results of an international collaboration—the Magnesium Front End Research and Development (MFERD) project—that is leveraging the expertise and resources of Canada, China and the United States to advance the creation of magnesium-intensive vehicles. The MFERD project aims to develop the enabling technologies and knowledge base that will lead to a vehicles that are 50-60 percent lighter, equally affordable, more recyclable and of equal or better quality when compared to today’s vehicles. Databases of information also will be captured in models to enable further alloy and manufacturing process optimization. Finally, a life-cycle analysis of the magnesium used will be conducted.

  12. Study of lattice dynamics of Fe2SiO4- and Mg2SiO4-spinels

    NASA Astrophysics Data System (ADS)

    Sinha, M. M.; Kaur, Harleen

    2016-10-01

    Fe2SiO4 is an end member of Mg-rich (Mg, Fe)2SiO4, which is believed to be a major mineral of the Earth's transition zone [1, 2]. The presence of iron has a pronounced effect on elastic and thermodynamic properties of rock-forming minerals. These properties play crucial role in the interpretation of the geophysical data and thus have a large influence on our knowledge of the earth's interior. An understanding of the elastic properties of silicate will be further helpful to the interpretation of seismological data, in particular the variation in the depth range of transition zone of earth's interior. The spinel form of magnesium-iron orthosilicate, (Mg, Fe)2SiO4, is believed to be one of the most abundant minerals in the mantle's transition zone and is found to be stable in ambient conditions and therefore, a detailed study of zone centre phonons of this stable phase of orthosilicates (Mg, Fe)2SiO4 is of high interest. Hence, in the present study, the zone centre phonons of antiferromagnetic Fe2SiO4-spinel and Mg2SiO4-spinel have been studied by using short range force constant model involving interatomic interactions upto first three neighbours. The zone centre phonons of Fe2SiO4 is compared with that of Mg2SiO4 in order to study the effect of the cation exchange on the dynamic and thermodynamic properties of (Mg, Fe)2SiO4-spinel. The calculated results are compared and analyzed with exiting experimental results.

  13. Microstructural and physical properties of magnesium oxide-doped silicon nitride ceramics

    NASA Astrophysics Data System (ADS)

    Sirota, V.; Lukianova, O.; Krasilnikov, V.; Selemenev, V.; Dokalov, V.

    Silicon nitride based ceramics with aluminum, yttrium and magnesium oxides were produced by cold isostatic pressing and free sintering. The phase composition of the starting MgO powder obtained by the novel technology has been studied. The effect of magnesium oxide content on the structure of the produced materials has been investigated. It was found, that obtained materials with 1 and 2 wt.% of magnesium oxide and without it have a typical β-silicon nitride structure with elongated grains. Ceramics with 5 wt.% magnesia has a duplex α/β-structure with elongated and equiaxed grains. Ceramics with 2 wt.% magnesium oxide has a maximum density of 2.91 g/cm3. The increases in magnesium oxide content upto 5% led to decrease in the shrinkage (from 16% to 12%) and density (from 2.88 to 2.37 g/cm3).

  14. Ionic modeling of lithium manganese spinel materials for use in rechargeable batteries

    SciTech Connect

    Cygan, R.T.; Westrich, H.R.; Doughty, D.H.

    1995-12-31

    In order to understand and evaluate materials for use in lithium ion rechargeable battery electrodes, the authors have modeled the crystal structures of various manganese oxide and lithium manganese oxide compounds. They have modeled the MnO{sub 2} polymorphs and several spinels with intermediate compositions based on the amount of lithium inserted into the tetrahedral site. Three-dimensional representations of the structures provide a basis for identifying site occupancies, coordinations, manganese valence, order-disorder, and potentially new dopants for enhanced cathode behavior. X-ray diffraction simulations of the crystal structures provide good agreement with observed patterns for synthesized samples. Ionic modeling of these materials consists of an energy minimization approach using Coulombic, repulsive, and van der Waals interactions. Modeling using electronic polarizability (shell model) allows a systematic analysis of changes in lattice energy, cell volume, and the relative stability of doped structures using ions such as aluminum, titanium, nickel, and cobalt.

  15. Quantitatively Predict the Potential of MnO2 Polymorphs as Magnesium Battery Cathodes.

    PubMed

    Ling, Chen; Zhang, Ruigang; Mizuno, Fuminori

    2016-02-01

    Despite tremendous efforts denoted to magnesium battery research, the realization of magnesium battery is still challenged by the lack of cathode candidate with high energy density, rate capability and good recyclability. This situation can be largely attributed to the failure to achieve sustainable magnesium intercalation chemistry. In current work we explored the magnesiation of distinct MnO2 polymorphs using first-principles calculations, focusing on providing quantitative analysis about the feasibility of magnesium intercalation. Consistent with experimental observations, we predicted that ramsdellite-MnO2 and α-MnO2 are conversion-type cathodes while nanosized spinel-MnO2 and MnO2 isostructual to CaFe2O4 are better candidates for Mg intercalation. Key properties that restrict Mg intercalation include not only sluggish Mg migration but also stronger distortion that damages structure integrity and undesirable conversion reaction. We demonstrate that by evaluating the reaction free energy, structural deformation associated with the insertion of magnesium, and the diffusion barriers, a quantitative evaluation about the feasibility of magnesium intercalation can be well established. Although our current work focuses on the study of MnO2 polymorphs, the same evaluation can be applied to other cathode candidates, thus paving the road to identify better cathode candidates in future.

  16. Pyroxene-spinel intergrowths in lunar and terrestrial pyroxenes

    NASA Technical Reports Server (NTRS)

    Okamura, F. P.; Mccallum, I. S.; Stroh, J. M.; Ghose, S.

    1976-01-01

    The paper describes the oriented intergrowth of spinel and pyroxene in a pigeonite from Luna 20, an augite from Apollo 16 anorthosite 67075, and an orthopyroxene from a spinel lherzolite nodule from the San Quintin volcanic field, Mexico. Using Mo K alpha radiation, photographs were taken of small, hand-picked single-crystals. A mechanism of exsolution is suggested in which the oxygen framework remains intact and spinel nuclei are formed by the migration of cations from interstitial sites and tetrahedral sites in the original non-stoichiometric pyroxene.

  17. Characterization of (Mg, La) Substituted Ni-Zn Spinel Ferrite

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Wei, S. C.; Wang, Y. J.; Tian, H. L.; Tong, H.; Xu, B. S.

    Spinel structure of (Mg, La) substituted spinel Ni-Zn ferrite has been synthesized by sol-gel auto combustion method. The ferrite exhibits a single-spinel structure. The ferrite is studied as a microwave absorbing material. The microwave measurements are carried out by a vector network analyzer. The reflection loss of the ferrite is calculated as a single-layer absorber. The results indicate that the ferrite annealed at 850°C has great potential for application in electromagnetic wave attenuation.

  18. 21 CFR 184.1434 - Magnesium phosphate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Magnesium phosphate. 184.1434 Section 184.1434... Listing of Specific Substances Affirmed as GRAS § 184.1434 Magnesium phosphate. (a) Magnesium phosphate includes both magnesium phosphate, dibasic, and magnesium phosphate, tribasic. Magnesium phosphate,...

  19. 21 CFR 184.1434 - Magnesium phosphate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Magnesium phosphate. 184.1434 Section 184.1434... Listing of Specific Substances Affirmed as GRAS § 184.1434 Magnesium phosphate. (a) Magnesium phosphate includes both magnesium phosphate, dibasic, and magnesium phosphate, tribasic. Magnesium phosphate,...

  20. 21 CFR 184.1434 - Magnesium phosphate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Magnesium phosphate. 184.1434 Section 184.1434... GRAS § 184.1434 Magnesium phosphate. (a) Magnesium phosphate includes both magnesium phosphate, dibasic, and magnesium phosphate, tribasic. Magnesium phosphate, dibasic (MgHPO4·3H2O, CAS Reg. No....

  1. Modeling dissolution in aluminum alloys

    NASA Astrophysics Data System (ADS)

    Durbin, Tracie Lee

    2005-07-01

    Aluminum and its alloys are used in many aspects of modern life, from soda cans and household foil to the automobiles and aircraft in which we travel. Aluminum alloy systems are characterized by good workability that enables these alloys to be economically rolled, extruded, or forged into useful shapes. Mechanical properties such as strength are altered significantly with cold working, annealing, precipitation-hardening, and/or heat-treatments. Heat-treatable aluminum alloys contain one or more soluble constituents such as copper, lithium, magnesium, silicon and zinc that individually, or with other elements, can form phases that strengthen the alloy. Microstructure development is highly dependent on all of the processing steps the alloy experiences. Ultimately, the macroscopic properties of the alloy depend strongly on the microstructure. Therefore, a quantitative understanding of the microstructural changes that occur during thermal and mechanical processing is fundamental to predicting alloy properties. In particular, the microstructure becomes more homogeneous and secondary phases are dissolved during thermal treatments. Robust physical models for the kinetics of particle dissolution are necessary to predict the most efficient thermal treatment. A general dissolution model for multi-component alloys has been developed using the front-tracking method to study the dissolution of precipitates in an aluminum alloy matrix. This technique is applicable to any alloy system, provided thermodynamic and diffusion data are available. Treatment of the precipitate interface is explored using two techniques: the immersed-boundary method and a new technique, termed here the "sharp-interface" method. The sharp-interface technique is based on a variation of the ghost fluid method and eliminates the need for corrective source terms in the characteristic equations. In addition, the sharp-interface method is shown to predict the dissolution behavior of precipitates in aluminum

  2. Powdered aluminum and oxygen rocket propellants: Subscale combustion experiments

    NASA Technical Reports Server (NTRS)

    Meyer, Mike L.

    1993-01-01

    Aluminum combined with oxygen has been proposed as a potential lunar in situ propellant for ascent/descent and return missions for future lunar exploration. Engine concepts proposed to use this propellant have not previously been demonstrated, and the impact on performance from combustion and two-phase flow losses could only be estimated. Therefore, combustion tests were performed for aluminum and aluminum/magnesium alloy powders with oxygen in subscale heat-sink rocket engine hardware. The metal powder was pneumatically injected, with a small amount of nitrogen, through the center orifice of a single element O-F-O triplet injector. Gaseous oxygen impinged on the fuel stream. Hot-fire tests of aluminum/oxygen were performed over a mixture ratio range of 0.5 to 3.0, and at a chamber pressure of approximately 480 kPa (70 psia). The theoretical performance of the propellants was analyzed over a mixture ratio range of 0.5 to 5.0. In the theoretical predictions the ideal one-dimensional equilibrium rocket performance was reduced by loss mechanisms including finite rate kinetics, two-dimensional divergence losses, and boundary layer losses. Lower than predicted characteristic velocity and specific impulse performance efficiencies were achieved in the hot-fire tests, and this was attributed to poor mixing of the propellants and two-phase flow effects. Several tests with aluminum/9.8 percent magnesium alloy powder did not indicate any advantage over the pure aluminum fuel.

  3. Relationship of aluminum to Alzheimer's disease.

    PubMed Central

    Perl, D P

    1985-01-01

    Alzheimer's disease is a progressive degenerative brain disease of unknown etiology, characterized by the development of large numbers of neurofibrillary tangles and senile plaques in the brain. Aluminum salts may be used experimentally to produce lesions which are similar, but not identical, to the neurofibrillary tangle. Although some studies have reported increased amounts of aluminum in the brains of Alzheimer's disease victims, these bulk analysis studies have been difficult to replicate and remain controversial. Using scanning electron microscopy with X-ray spectrometry, we have investigated this question on the cellular level. We have identified abnormal accumulations of aluminum within neurons derived from Alzheimer's disease patients containing neurofibrillary tangles. Similar accumulations have been detected in the numerous neurofibrillary tangle-bearing neurons seen in the brains of the indigenous native population of the island of Guam who suffer from amyotrophic lateral sclerosis and parkinsonism with dementia. Epidemiologic evidence strongly suggests a causal role for local environmental conditions relating to availability of aluminum, calcium, and magnesium. In view of the fact that a major consequence of acid rain is the liberation of large amounts of aluminum in bioavailable forms, concerns are raised about possible human health risks of this environmental phenomenon. PMID:4076080

  4. Reduction of Oxidative Melt Loss of Aluminum and Its Alloys

    SciTech Connect

    Dr. Subodh K. Das; Shridas Ningileri

    2006-03-17

    This project led to an improved understanding of the mechanisms of dross formation. The microstructural evolution in industrial dross samples was determined. Results suggested that dross that forms in layers with structure and composition determined by the local magnesium concentration alone. This finding is supported by fundamental studies of molten metal surfaces. X-ray photoelectron spectroscopy data revealed that only magnesium segregates to the molten aluminum alloy surface and reacts to form a growing oxide layer. X-ray diffraction techniques that were using to investigate an oxidizing molten aluminum alloy surface confirmed for the first time that magnesium oxide is the initial crystalline phase that forms during metal oxidation. The analytical techniques developed in this project are now available to investigate other molten metal surfaces. Based on the improved understanding of dross initiation, formation and growth, technology was developed to minimize melt loss. The concept is based on covering the molten metal surface with a reusable physical barrier. Tests in a laboratory-scale reverberatory furnace confirmed the results of bench-scale tests. The main highlights of the work done include: A clear understanding of the kinetics of dross formation and the effect of different alloying elements on dross formation was obtained. It was determined that the dross evolves in similar ways regardless of the aluminum alloy being melted and the results showed that amorphous aluminum nitride forms first, followed by amorphous magnesium oxide and crystalline magnesium oxide in all alloys that contain magnesium. Evaluation of the molten aluminum alloy surface during melting and holding indicated that magnesium oxide is the first crystalline phase to form during oxidation of a clean aluminum alloy surface. Based on dross evaluation and melt tests it became clear that the major contributing factor to aluminum alloy dross was in the alloys with Mg content. Mg was

  5. Design for aluminum recycling

    SciTech Connect

    Not Available

    1993-10-01

    This article describes the increasing use of aluminum in automobiles and the need to recycle to benefit further growth of aluminum applications by assuring an economical, high-quality source of metal. The article emphasizes that coordination of material specifications among designers can raise aluminum scrap value and facilitate recycling. Applications of aluminum in automobile construction are discussed.

  6. Optical planar waveguide in magnesium aluminate spinel crystal using oxygen ion implantation

    NASA Astrophysics Data System (ADS)

    Song, Hong-Lian; Yu, Xiao-Fei; Zhang, Lian; Wang, Tie-Jun; Qiao, Mei; Liu, Peng; Zhao, Jin-Hua; Wang, Xue-Lin

    2015-07-01

    A planar optical waveguide in MgAl2O4 crystal sample was fabricated using 6.0 MeV oxygen ion implantation at a fluence of 1.5 × 1015 ions/cm2 at room temperature. The optical modes were measured at a wavelength of 633 nm using a model 2010 prism coupler. The near-field intensity files in the visible band were measured and simulated with end-face coupling and FD-BPM methods, respectively. The absorption spectra show that the implantation process has almost no effect on the visible and near-infrared band absorption.

  7. Corrosion in Magnesium and a Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Akavipat, Sanay

    Magnesium and a magnesium alloy (AZ91C) have been ion implanted over a range of ions energies (50 to 150 keV) and doses (1 x 10('16) to 2 x 10('17) ions/cm('2)) to modify the corrosion properties of the metals. The corrosion tests were done by anodic polarization in chloride -free and chloride-containing aqueous solutions of a borated -boric acid with a pH of 9.3. Anodic polarization measurements showed that some implantations could greatly reduce the corrosion current densities at all impressed voltages and also increased slightly the pitting potential, which indicated the onset of the chloride attack. These improvements in corrosion resistance were caused by boron implantations into both types of samples. However, iron implantations were found to improve only the magnesium alloy. To study the corrosion in more detail, Scanning Auger Microprobe Spectrometer (SAM), Scanning Electron Microscope (SEM) with an X-ray Energy Spectrometry (XES) attachment, and Transmission Electron Microscope (TEM) measurements were used to analyze samples before, after, and at various corrosion stages. In both the unimplanted pure magnesium and AZ91C samples, anodic polarization results revealed that there were three active corrosion stages (Stages A, C, and E) and two passivating stages (Stages B and D). Examination of Stages A and B in both types of samples showed that only a mild, generalized corrosion had occurred. In Stage C of the TD samples, a pitting breakdown in the initial oxide film was observed. In Stage C of the AZ91C samples, galvanic and intergranular attack around the Mg(,17)Al(,12) intermetallic islands and along the matrix grain boundaries was observed. Stage D of both samples showed the formation of a thick, passivating oxygen containing, probably Mg(OH)(,2) film. In Stage E, this film was broken down by pits, which formed due to the presence of the chloride ions in both types of samples. Stages A through D of the unimplanted samples were not seen in the boron or iron

  8. Magnesium Metabolism and its Disorders

    PubMed Central

    Swaminathan, R

    2003-01-01

    Magnesium is the fourth most abundant cation in the body and plays an important physiological role in many of its functions. Magnesium balance is maintained by renal regulation of magnesium reabsorption. The exact mechanism of the renal regulation is not fully understood. Magnesium deficiency is a common problem in hospital patients, with a prevalence of about 10%. There are no readily available and easy methods to assess magnesium status. Serum magnesium and the magnesium tolerance test are the most widely used. Measurement of ionised magnesium may become more widely available with the availability of ion selective electrodes. Magnesium deficiency and hypomagnesaemia can result from a variety of causes including gastrointestinal and renal losses. Magnesium deficiency can cause a wide variety of features including hypocalcaemia, hypokalaemia and cardiac and neurological manifestations. Chronic low magnesium state has been associated with a number of chronic diseases including diabetes, hypertension, coronary heart disease, and osteoporosis. The use of magnesium as a therapeutic agent in asthma, myocardial infarction, and pre-eclampsia is also discussed. Hypermagnesaemia is less frequent than hypomagnesaemia and results from failure of excretion or increased intake. Hypermagnesaemia can lead to hypotension and other cardiovascular effects as well as neuromuscular manifestations. Causes and management of hypermagnesaemia are discussed. PMID:18568054

  9. Rugged spinel windows and optics for harsh environments

    NASA Astrophysics Data System (ADS)

    Bayya, Shyam; Villalobos, Guillermo; Kim, Woohong; Busse, Lynda; Sanghera, Jasbinder; Aggarwal, Ishwar

    2013-05-01

    Spinel is a rugged ceramic transparent from ultraviolet to midwave infrared (0.18 - 5.5 μm) wavelengths. It has the best transmission from 4-5 μm among the competing materials ALON and sapphire with comparable mechanical properties. We have developed low absorption loss spinel as an exit window aperture for High Energy Laser systems. We demonstrated that spinel possesses excellent thermo-optical characteristics required for the High Energy Laser systems and at the same time it can provide the necessary ruggedness desired for the realistic and harsh battlefield environment. We have demonstrated through testing that spinel can withstand very adverse conditions of rain, sand storms and salt fog conditions without any change in its optical performance. We have also developed rugged anti-reflective coatings and anti-reflective surface structures to maintain high optical transmission in adverse environment.

  10. Sustainable synthesis of monodispersed spinel nano-ferrites

    EPA Science Inventory

    A sustainable approach for the synthesis of various monodispersed spinel ferrite nanoparticles has been developed that occurs at water-toluene interface under both conventional and microwave hydrothermal conditions. This general synthesis procedure utilizes readily available and ...

  11. Infrared spectra of olivine polymorphs - Alpha, beta phase and spinel

    NASA Technical Reports Server (NTRS)

    Jeanloz, R.

    1980-01-01

    The infrared absorption spectra of several olivines (alpha phase) and their corresponding beta phase (modified spinel) and spinel (gamma) high-pressure polymorphs are determined. Spectra were measured for ground and pressed samples of alpha and gamma A2SiO4, where A = Fe, Ni, Co; alpha and gamma Mg2GeO4; alpha Mg2SiO4; and beta Co2SiO4. The spectra are interpreted in terms of internal, tetrahedral and octagonal, and lattice vibration modes, and the spinel results are used to predict the spectrum of gamma Mg2SiO4. Analysis of spectra obtained from samples of gamma Mg2GeO4 heated to 730 and 1000 C provides evidence that partial inversion could occur in silicate spinels at elevated temperatures and pressures.

  12. Effect of the Filter Surface Chemistry on the Filtration of Aluminum

    NASA Astrophysics Data System (ADS)

    Voigt, Claudia; Fankhänel, Beate; Jäckel, Eva; Aneziris, Christos G.; Stelter, Michael; Hubálková, Jana

    2015-04-01

    The influence of the filter surface chemistry of alumina skeletons on the filtration effect was tested with five different oxide coating materials (Al2O3, spinel, mullite, TiO2, and SiO2). All prepared filters were casted successfully under industrial conditions. The casted aluminum samples showed no contamination caused by the filters. The evaluation of the casted filters by means of SEM and EDX showed that the amount of inclusions in the area of the run in is larger than in the middle and the run out of the filter. The most non-metallic inclusions were found in the casted filters Al2O3+Al2O3 and Al2O3+spinel. The wetting experiments yielded for all tested materials a non-wetting behavior whereby Al2O3 and spinel showed higher wetting angle than mullite, TiO2, and SiO2.

  13. Proficient magnesium nanoferrites: synthesis and characterization

    NASA Astrophysics Data System (ADS)

    Anis-ur-Rehman, M.; Malik, Muhammad Ali; Akram, M.; Khan, Kishwar; Maqsood, Asghari

    2011-01-01

    Ferrite materials are potential candidates for modern technological applications because of their tunable electrical and magnetic properties. The excellent combination of magnetic and dielectric properties of magnesium ferrites can be used to fulfill the future demand for high-frequency applications such as antennas. The electrical transport properties of these materials depend on the synthesis conditions such as sintering and composition. The aim of this work has been to correlate the synthesis conditions and induced electrical transport properties, so that these materials prepared in optimized conditions can be used for the miniaturization of high-frequency application devices. X-ray diffraction (XRD) patterns of samples prepared by the co-precipitation method confirmed the formation of a single spinel phase. The crystallite size, lattice parameters and porosity of the samples were calculated from XRD data. The scanning electron microscopy results showed the formation of rods in the case of the samples sintered at 950 °C. All the electrical and dielectric properties showed strong dependence on structural properties. The dielectric constant, dielectric loss tangent and ac electrical conductivity of nanocrystalline Mg ferrites were investigated as a function of frequency and sintering temperature. Dielectric, ac electrical properties and the effect of sintering temperature are explained in accordance with the Maxwell-Wagner and the Koops models.

  14. Effects of thermal metamorphism on compositions of lunar spinels

    NASA Technical Reports Server (NTRS)

    Misra, K. C.; Taylor, L. A.

    1977-01-01

    The reported study represents an attempt to evaluate experimentally the compositional and textural changes that are likely to be observed in the Fe-Ti-Cr spinels of lunar igneous rocks by subsequent thermal metamorphism. The Apollo 12 igneous rock, 12018,43, was chosen for this investigation because an earlier study of another fraction of this rock by El Goresy et al. (1971) has reported an almost continuous trend of spinel compositions between Cr-Ulvoespinel and Ti-chromite. The nature of the compositional changes in the heated spinels (and ilmenites) is found to be such that the changes cannot be explained by intragranular adjustments alone. In the heated sample, pyroxene grains adjacent to the high-Ti spinels show a decrease in FeO, and an increase in MgO and Al2O3 at the interface. This may account for the MgO depletion and a part of the FeO enrichment in the high-Ti spinels. It is believed that the heating experiment demonstrates that thermal metamorphism of lunar basalts is likely to modify the compositions of their preexisting spinels (and ilmenites).

  15. Shear Strength of Aluminum Oxynitride

    NASA Astrophysics Data System (ADS)

    Dandekar, Dattatraya P.; Vaughan, Brian A. M.; Proud, William G.

    2007-06-01

    Aluminum oxynitride (AlON) is a transparent, polycrystalline cubic spinel. The results of investigations^1-4 on shock response of AlON permit determination of the equation of state, and shear strength retained under shock compression. Whereas the values of the HEL of AlON holds no surprises, the inelastic response of AlON reported in Ref. 1-4 differ significantly and is stress dependent. The results of Ref. 1-2 show that AlON retains a shear strength of 3 to 4 GPa when shocked up to around 20 GPa, but the results of Ref, 3-4 seem to suggest a possible loss of shear strength when shocked to 16 GPa and beyond. Our analysis examines the observed differences in the inelastic response of AlON reported in these four studies . 1. J. U. Cazamias, et. al., in Fundamental Issues and Applications of Shock-Wave and High Strain Rate Phenomena, Eds. Staudhammer, Murr, and Meyers, Elsevier, NY, 173 (2001). 2. B. A. M. Vaughn, et.al., Shock Physics, Cavendish Laboratory, Report SP/1092 (2001) 3. T. Sekine, et.al., J. Appl. Phys. 94, 4803 (2003). 4. T. F. Thornhill, et.al., Shock Compression of Matter-2005, Eds. Furnish, Elert, Russell, White, AIP, NY, 143 (2006).

  16. Welding the four most popular aluminum alloys

    SciTech Connect

    Irving, B.

    1994-02-01

    The fact that business is good in aluminum welding is a sure sign that more manufacturers and fabricators are using GMA and GTA welding to build new products out of this lightweight nonferrous metal. Among the most widely specified weldable grades are Alloys 6061, 5083, 5052 and 5454. A rundown on these four alloys, including properties and selected applications, is provided. Any company working with aluminum for the first time needs to know something about these four alloys. Alloys of copper-magnesium-silicon combination, of which 6061 is one, are heat-treatable. The three 5XXX series alloys, on the other hand, are nonheat-treatable. According to P.B. Dickerson, consultant, Lower Burrell, Pa., 5083, because of its high magnesium content, is the easiest of the four alloys to arc weld. Dickerson put the cut-off point in weldability at 3.5% magnesium. To prevent cracking, he added, both 6061 and 5052 require much more filler metal than do the other two alloys. Alloy 6061 consists of 0.25Cu, 0.6Si, 1.0Mg, and 0.20Cr. The main applications for 6061 aluminum are structural, architectural, automotive, railway, marine and pipe. It has good formability, weldability, corrosion resistance and strength. Although the 6XXX series alloys are prone to hot cracking, this condition can be readily overcome by correct choice of joint design and electrode. The most popular temper for 6061 is T6, although the -T651, -T4, and -F temper are also popular. The -T651 temper is like a -T6 temper, only it has received some final stretch hardening. The -T4 temper has been solution heat-treated and quenched. The -F temper is in the as-fabricated condition.

  17. Emerging Environment Friendly, Magnesium-Based Composite Technology for Present and Future Generations

    NASA Astrophysics Data System (ADS)

    Meenashisundaram, G. K.; Gupta, M.

    2016-07-01

    Magnesium is the lightest and one of the most abundant elements in the universe. In addition, magnesium possesses several other benefits like excellent castability, high damping capacity, good electromagnetic shielding, and excellent machinability. These inherent characteristics of magnesium-based materials ensure fuel economy, reduced CO2 emissions, and a greener earth. Furthermore, as magnesium-based materials are almost 35% lighter than aluminum-based materials, a tremendous surge in magnesium demand over the next 5 years is expected. One way in which the engineering capabilities of magnesium and its alloys can further be enhanced is to use composite technology. The addition of nanoparticles, for example, leads to enhanced tensile, compressive, fatigue, creep, dynamic, tribological, and corrosion properties. In addition, amorphous and hollow reinforcements can also enhance targeted mechanical/physical properties. Accordingly, the present study will highlight the key capabilities of magnesium-based composite technology. An attempt is made to summarize on the size effects and type of reinforcements such as metallic or ceramic nanoparticles, and amorphous and hollow reinforcements on the microstructural and mechanical properties of monolithic pure magnesium.

  18. Magnesium Research and Technology Development

    SciTech Connect

    Nyberg, Eric A.; Joost, William; Smith, Mark T.

    2009-12-30

    The Magnesium Research and Technical Development (MR&TD) project supports efforts to increase using magnesium in automotive applications, including improving technology, lowering costs and increasing the knowledge needed to enable alloy and manufacturing process optimization. MR&TD supports the U.S. Department of Energy (DOE)/United States Automotive Materials Partnership (USAMP) Magnesium Front End Research and Development (MFERD) project in collaboration with China and Canada. The MR&TD projects also maintains the magnesium bibliographic database at magnesium.pnl.gov.

  19. The Role of Spinel Minerals in Lunar Magma Evolution

    NASA Astrophysics Data System (ADS)

    Taylor, L. A.; Head, J. W.; Pieters, C. M.; Sunshine, J. M.; Staid, M.; Isaacson, P.; Petro, N. E.

    2009-12-01

    The Moon Mineralogy Mapper (M3), a NASA guest instrument on Chandrayaan-1, India’s first mission to the Moon, was designed to map the surface mineralogy of the Moon using reflected solar radiation at visible and near-infrared wavelengths, which contain highly diagnostic absorptions due to minerals. The M3 spectrometer has discovered several new and unexpected aspects of the geology and petrology of the Moon, some involving specific oxide phases. Spinel minerals, with the general formula, AB2O4, present clues as to the oxygen fugacity, the nature of magmatic systems, and their evolution, particularly during the early stages of crystallization. On the Moon, with its total lack of Fe3+ and minerals such as magnetite, observed spinels range between spinel, MgAl2O4; hercynite, FeAl2O4; Chromite, FeCr2O4; and ulvöspinel, Fe(FeTi)2O4. They manifest themselves in three distinctly different igneous rock types: highlands rocks of anorthosites/troctolites, gabbro-norites; mare basalts with various TiO2 contents; and basaltic pyroclastic volcanic glasses. Although spinels occur as minor minerals in the Apollo collection, unique rock types dominated by Mg-spinel (with olivine and pyroxene abundances below detection limits, assumed to be ~5%) have been identified by M3 on the Moon. Because the spinel-bearing rocks detected by M3 have no signature of a significant olivine component, they must be dominated by plagioclase and spinel. Pink Mg-spinels typically occur as a minor phase in troctolites (plagioclase + olivine), a highland rock formed after the initial Ferroan Anorthosite (FAN) crust, presumably by serial magmatism deep within the crust, with intrusion upward. FANs were formed by floatation of plagioclase in the lunar magma ocean (LMO), whereas spinels would sink due to their much higher density. Thus, a plagioclase-rich rock type with a strong Mg-spinel spectral signature would have to be part of later highland intrusives. The excess Mg-spinel could be the product of

  20. 76 FR 18521 - Aluminum Extrusions From the People's Republic of China: Final Affirmative Countervailing Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-04

    ... designations are representative of aluminum alloys for casting: 208.0, 295.0, 308.0, 355.0, C355.0, 356.0, A356... not more than 3.0 percent of total materials by weight. The subject merchandise is made from an... magnesium and silicon as the major alloying elements, with magnesium accounting for at least 0.1 percent...

  1. A lightweight shape-memory magnesium alloy

    NASA Astrophysics Data System (ADS)

    Ogawa, Yukiko; Ando, Daisuke; Sutou, Yuji; Koike, Junichi

    2016-07-01

    Shape-memory alloys (SMAs), which display shape recovery upon heating, as well as superelasticity, offer many technological advantages in various applications. Those distinctive behaviors have been observed in many polycrystalline alloy systems such as nickel titantium (TiNi)-, copper-, iron-, nickel-, cobalt-, and Ti-based alloys but not in lightweight alloys such as magnesium (Mg) and aluminum alloys. Here we present a Mg SMA showing superelasticity of 4.4% at -150°C and shape recovery upon heating. The shape-memory properties are caused by reversible martensitic transformation. This Mg alloy includes lightweight scandium, and its density is about 2 grams per cubic centimeter, which is one-third less than that of practical TiNi SMAs. This finding raises the potential for development and application of lightweight SMAs across a number of industries.

  2. Recovery and distribution of incinerated aluminum packaging waste.

    PubMed

    Hu, Y; Bakker, M C M; de Heij, P G

    2011-12-01

    A study was performed into relations between physical properties of aluminum packaging waste and the corresponding aluminum scraps in bottom ash from three typical incineration processes. First, Dutch municipal solid waste incineration (MSWI) bottom ash was analyzed for the identifiable beverage can alloy scraps in the +2mm size ranges using chemical detection and X-ray fluorescence. Second, laboratory-scale pot furnace tests were conducted to investigate the relations between aluminum packaging in base household waste and the corresponding metal recovery rates. The representative packaging wastes include beverage cans, foil containers and thin foils. Third, small samples of aluminum packaging waste were incinerated in a high-temperature oven to determine leading factors influencing metal recovery rates. Packaging properties, combustion conditions, presence of magnesium and some specific contaminants commonly found in household waste were investigated independently in the high-temperature oven. In 2007, the bottom ash (+2mm fraction) from the AEB MSWI plant was estimated to be enriched by 0.1 wt.% of aluminum beverage cans scrap. Extrapolating from this number, the recovery potential of all eleven MSWI plants in the Netherlands is estimated at 720 ton of aluminum cans scrap. More than 85 wt.% of this estimate would end up in +6mm size fractions and were amenable for efficient recycling. The pot furnace tests showed that the average recovery rate of metallic aluminum typically decreases from beverage cans (93 wt.%) to foil containers (85 wt.%) to thin foils (77 wt.%). The oven tests showed that in order of decreasing impact the main factors promoting metallic aluminum losses are the packaging type, combustion temperature, residence time and salt contamination. To a lesser degree magnesium as alloying element, smaller packaging size and basic contaminations may also promote losses.

  3. Superplasticity and cavitation in an aluminum-magnesium alloy

    NASA Astrophysics Data System (ADS)

    Bae, Donghyun

    2000-10-01

    Fundamental issues related to the forming performance of superplastic metals include the mechanisms of flow and cavitation occurring during the forming process. Cavitation beyond a critical amount is damaging to the mechanical behavior of fabricated parts. Therefore, the role of process parameters which influence cavitation must be precisely documented and understood. In this study, (1) the mechanism of deformation, (2) cavity formation and growth, and (3) the effect of forming parameters on cavitation are systematically investigated in a fine grain Al-4.7%Mg-0.8%Mn-0.4%Cu alloy. The mechanical flow response of the alloy is characterized by a new type of step strain-rate test which preserves the initial microstructure of the alloy. Under isostructural condition, sigmoidal log s vs. log 3˙ relationship is determined and then analyzed by using a grain-mantle based quantitative model1 for superplastic flow. The activation energies in both grain-mantle creep and core creep are analyzed, and the overall controlling mechanism is found to be dislocation glide and climb. Grain-mantle creep rate in the low strain-rate region is found to be enhanced many times due to a high concentration of vacancies near grain boundaries. Cavitation caused by superplastic straining under uniaxial tension is evaluated by the SEM (for < 0.5mum size) and the number and size of cavities are monitored by image analysis through optical microscopy. Growth of pre-existing cavities and nucleation and growth of new cavities at grain boundary particles are monitored with increasing strain. Cavity nucleation and growth occur in two stages: crack-like growth along the particle-matrix interface by a constrained growth process, and beyond complete debonding growth via plastic deformation of the matrix which is modeled here. Stresses and strain-rates near the void are intensified due to the perturbed flow field near the void, and not relaxed during the time frame associated with superplastic deformation. In the model, faster cavity growth is predicted for lower m and for smaller cavity density when cavity stress fields are not overlapping. Observed cavitation quantitatively agrees with the present model, but diffusional growth is found to be too slow, which cannot explain the observed nanoscale void growth behavior. Another parameter affecting the degree of cavitation is the imposed stress-state. Cavity growth rate as well as cavity nucleation rate increase with the level of mean hydrostatic tension. For a fixed cavitation volume fraction, V, the principal surface strains, 31 and 32 , for the various stress-states can be empirically given by: 31=aVb -a32 , where a and b are constants determined from 31 values for plane-strain 32=0 . The value of b is found to be 0.2 ˜ 0.3, and alpha is 0.4 ˜ 1. 1 A. K. Ghosh, Mat. Sci. Forum, Trans. Tech. Publications, Switzerland, 170--172, 39 (1994).

  4. Development and Approvals on Titanium, Magnesium and Aluminum Composites

    DTIC Science & Technology

    2011-02-08

    25 Ti6Al4V wear Ti6Al4V against SAE52100 steel , block-on-ring dry sliding wear test PEO layers obtained from mixed aluminate –phosphate baths on Ti–6Al...1400 1600 1800 P in -o n -d is c (m /m m 3 ) Hardness (HV0.1) PEO (on Al 7075) HA (on Al 7075) 5140 steel Hardness & wear resistance 2 α-Al2O3... steel , sand, glass and many common wear counterparts. This hardness is typically reflected in wear performance: © Keronite 2011 11 Wear protection 09

  5. Method to decrease loss of aluminum and magnesium melts

    SciTech Connect

    Hryn, John N.; Pellin, Michael J.; Calaway, Jr., Wallis F.; Moore, Jerry F.; Krumdick, Gregory K.

    2002-01-01

    A method to minimize oxidation of metal during melting processes is provided, the method comprising placing solid phase metal into a furnace environ-ment, transforming the solid-phase metal into molten metal phase having a molten metal surface, and creating a barrier between the surface and the environment. Also provided is a method for isolating the surface of molten metal from its environment, the method comprising confining the molten metal to a controlled atmos-phere, and imposing a floating substrate between the surface and the atmosphere.

  6. Interdiffusion in Ternary Magnesium Solid Solutions of Aluminum and Zinc

    DOE PAGES

    Kammerer, Catherine; Kulkarni, Nagraj S; Warmack, Robert J Bruce; ...

    2016-01-11

    Al and Zn are two of the most common alloying elements in commercial Mg alloys, which can improve the physical properties through solid solution strengthening and precipitation hardening. Diffusion plays a key role in the kinetics of these and other microstructural design relevant to Mg-alloy development. However, there is a lack of multicomponent diffusion data available for Mg alloys. Through solid-to-solid diffusion couples, diffusional interactions of Al and Zn in ternary Mg solid-solution at 400° and 450 °C were examined by an extension of the Boltzmann-Matano analysis based on Onsager s formalism. Concentration profiles of Mg-Al-Zn ternary alloys were determinedmore » by electron probe microanalysis, and analyzed to determine the ternary interdiffusion coefficients as a function of composition. Zn was determined to interdiffuse the fastest, followed by Mg and Al. Appreciable diffusional interactions among Mg, Al, and Zn were observed by variations in sign and magnitude of cross interdiffusion coefficients. In particular, Zn was found to significantly influence the interdiffusion of Mg and Al significantly: the and ternary cross interdiffusion coefficients were both negative, and large in magnitude, in comparison to and , respectively. Al and Mg were observed influence the interdiffusion of Mg and Al, respectively, with positive and interdiffusion coefficients, but their influence on the Zn interdiffusion was negligible.« less

  7. Interdiffusion in Ternary Magnesium Solid Solutions of Aluminum and Zinc

    SciTech Connect

    Kammerer, Catherine; Kulkarni, Nagraj S; Warmack, Robert J Bruce; Sohn, Yong Ho

    2016-01-11

    Al and Zn are two of the most common alloying elements in commercial Mg alloys, which can improve the physical properties through solid solution strengthening and precipitation hardening. Diffusion plays a key role in the kinetics of these and other microstructural design relevant to Mg-alloy development. However, there is a lack of multicomponent diffusion data available for Mg alloys. Through solid-to-solid diffusion couples, diffusional interactions of Al and Zn in ternary Mg solid-solution at 400° and 450 °C were examined by an extension of the Boltzmann-Matano analysis based on Onsager s formalism. Concentration profiles of Mg-Al-Zn ternary alloys were determined by electron probe microanalysis, and analyzed to determine the ternary interdiffusion coefficients as a function of composition. Zn was determined to interdiffuse the fastest, followed by Mg and Al. Appreciable diffusional interactions among Mg, Al, and Zn were observed by variations in sign and magnitude of cross interdiffusion coefficients. In particular, Zn was found to significantly influence the interdiffusion of Mg and Al significantly: the and ternary cross interdiffusion coefficients were both negative, and large in magnitude, in comparison to and , respectively. Al and Mg were observed influence the interdiffusion of Mg and Al, respectively, with positive and interdiffusion coefficients, but their influence on the Zn interdiffusion was negligible.

  8. Effect of magnesium on relaxation frequency of Ni-Zn nanoferrites

    NASA Astrophysics Data System (ADS)

    Ganga Swamy, D. R. S.; Chaitanya Varma, M.; Bharadwaj, S.; Sambasiva Rao, K.; Rao, K. H.

    2015-10-01

    Ni0.65-xMgxZn0.35Fe2O4 (x = 0, 0.4, 0.8, 0.10, 0.12 and 0.16) samples have been synthesized by sol-gel method using polyvinyl alcohol (PVA) as chelating agent. The synthesized samples were sintered at 1000∘C for 1 h. The X-ray diffraction (XRD) confirms single phase spinel structure and scanning electron microscope (SEM) confirms the uniform grain with increasing grain growth with increase concentration of magnesium (Mg) (x). A slight increase in saturation magnetization (VSM) has been observed for low concentrations of magnesium which disappear for higher concentrations of magnesium (x > 0.12) in these materials. Decrease in room temperature DC resistivity with magnesium concentration has been attributed to grain growth. The permeability measured for the ferrites exhibits high permeability for increase in the magnesium content. The permeability behavior is understood on the basis of domain wall contribution and grain growth. Frequency dependence of permeability as measured suggests that the suitability of all the samples for high frequency core applications as the operating frequency lies beyond 110 MHz.

  9. Effect Of Neodymium Substitution In Structural Characteristics Of Magnesium Ferrite

    SciTech Connect

    Thankachan, Smitha; Binu, P. J.; Xavier, Sheena; Mohammed, E. M.

    2011-10-20

    The effect of Nd{sup 3+} substitution on the structural properties of Magnesium ferrite was studied in the series MgNd{sub x}Fe{sub 2-x}O{sub 4}, where x = 0 to 0.3 in steps of 0.05. The series was prepared by sol-gel technique which is one of the novel technique to prepare nanosized samples. Structural characterization was done using X-ray diffractometer and Fourier Transform Infrared Spectrometer. XRD analysis reveals the prepared samples are single phasic till x = 0.2. From x0 = .25, a secondary phase of iron neodymium oxide appears along with the spinel phase. Particle size calculation shows the prepared samples are in the 9nm to 11 nm regime. Lattice parameter was found to increase with concentration of Nd. XRD and FTIR analysis confirmed spinel structure of the prepared samples. XRF result shows the expected composition of prepared samples. The frequency dependence of the dielectric constant in the range 100 Hz--120MHz was also studied

  10. Corrosion Behavior of Aluminum-Steel Weld-Brazing Joint

    NASA Astrophysics Data System (ADS)

    Shi, Yu; Li, Jie; Zhang, Gang; Huang, Jiankang; Gu, Yufen

    2016-05-01

    Dissimilar metals of 1060 aluminum and galvanized steel were joined with a lap joint by pulsed double-electrode gas metal arc weld brazing with aluminum-magnesium and aluminum-silicon filler metals. The corrosion behavior of the weld joints was investigated with immersion corrosion and electrochemical corrosion tests, and the corrosion morphology of the joints was analyzed with scanning electron microscopy (SEM). Galvanic corrosion was found to occur when the samples were immersed in corrosive media, and the corrosion rate of joints was increased with increased heat input of the workpiece. Comparison of the corrosion properties of weld joints with different filler wires indicated that the corrosion rate of weld joints with aluminum-silicon filler wire was larger than that of weld joints with aluminum-magnesium filler wire. Results also showed that the zinc-rich zone of weld joints was prone to corrosion. The corrosion behavior of zinc-rich zone was analyzed with SEM equipped with an energy-dispersive x-ray spectroscopy analysis system based on the test results.

  11. Potential applications of wrought magnesium alloys for passenger vehicles

    SciTech Connect

    Gaines, L.; Cuenca, R.; Stodolsky, F.; Wu, S.

    1995-12-31

    Vehicle weight reduction is one of the major means available for improving automotive fuel efficiency. Although high-strength steels, aluminum (Al), and polymers are already being used to achieve significant weight reductions, substantial additional weight reductions could be achieved by increased use of magnesium (Mg) and its alloys, which have very low density. Magnesium alloys are currently used in relatively small quantities for auto parts; use is generally limited to die castings, such as housings. The Center for Transportation Research at Argonne National Laboratory has performed a study for the Lightweight Materials Program within DOE`s Office of Transportation Materials to evaluate the suitability of wrought Mg and its alloys to replace steel or aluminum for automotive structural and sheet applications. This study identifies technical and economic barriers to this replacement and suggests R&D areas to enable economical large-volume use. Detailed results of the study will be published at a later date. Magnesium sheet could be used in body nonstructural and semi-structural applications, while extrusions could be used in such structural applications as spaceframes. Currently, Mg sheet has found limited use in the aerospace industry, where costs are not a major concern. The major barrier to greatly increased automotive use is high cost; two technical R&D areas are identified that could enable major reductions in costs. These are novel reduction technology and better hot-forming technology, possibly operating at lower temperatures and involving superplastic behavior.

  12. An Environmentally Friendly Process Involving Refining and Membrane-Based Electrolysis for Magnesium Recovery from Partially Oxidized Scrap Alloy

    NASA Astrophysics Data System (ADS)

    Guan, Xiaofei; Pal, Uday B.; Powell, Adam C.

    2013-10-01

    Magnesium is recovered from partially oxidized scrap alloy by combining refining and solid oxide membrane (SOM) electrolysis. In this combined process, a molten salt eutectic flux (45 wt.% MgF2-55 wt.% CaF2) containing 10 wt.% MgO and 2 wt.% YF3 was used as the medium for magnesium recovery. During refining, magnesium and its oxide are dissolved from the scrap into the molten flux. Forming gas is bubbled through the flux and the dissolved magnesium is removed via the gas phase and condensed in a separate condenser at a lower temperature. The molten flux has a finite solubility for magnesium and acts as a selective medium for magnesium dissolution, but not aluminum or iron, and therefore the magnesium recovered has high purity. After refining, SOM electrolysis is performed in the same reactor to enable electrolysis of the dissolved magnesium oxide in the molten flux producing magnesium at the cathode and oxygen at the SOM anode. During SOM electrolysis, it is necessary to decrease the concentration of the dissolved magnesium in the flux to improve the faradaic current efficiency and prevent degradation of the SOM. Thus, for both refining and SOM electrolysis, it is very important to measure and control the magnesium solubility in the molten flux. High magnesium solubility facilitates refining whereas lower solubility benefits the SOM electrolysis process. Computational fluid dynamics modeling was employed to simulate the flow behavior of the flux stirred by the forming gas. Based on the modeling results, an optimized design of the stirring tubes and its placement in the flux are determined for efficiently removing the dissolved magnesium and also increasing the efficiency of the SOM electrolysis process.

  13. Nondestructive spot test method for magnesium and magnesium alloys

    NASA Technical Reports Server (NTRS)

    Wilson, M. L. (Inventor)

    1973-01-01

    A method for spot test identification of magnesium and various magnesium alloys commonly used in aerospace applications is described. The spot test identification involves color codes obtained when several drops of 3 M hydrochloric acid are placed on the surface to be tested. After approximately thirty seconds, two drops of this reacted acid is transferred to each of two depressions in a spot plate for additions of other chemicals with subsequent color changes indicating magnesium or its alloy.

  14. Highly Soluble Alkoxide Magnesium Salts for Rechargeable Magnesium Batteries

    SciTech Connect

    Liao, Chen; Guo, Bingkun; Jiang, Deen; Custelcean, Radu; Mahurin, Shannon Mark; Sun, Xiao-Guang; Dai, Sheng

    2014-01-01

    A unique class of air-stable and non-pyrophoric magnesium electrolytes has been developed based on alkoxide magnesium compounds. The crystals obtained from this class of electrolytes exhibit a unique structure of tri-magnesium cluster, [Mg3Cl3(OR)2(THF)6]+ [(THF)MgCl3] . High reversible capacities and good rate capabilities were obtained in Mg-Mo6S8 batteries using these new electrolytes at both 20 and 50 oC.

  15. Stabilization of MgAl2O4 spinel surfaces via doping

    SciTech Connect

    Hasan, Md. M.; Dholabhai, Pratik P.; Castro, Ricardo H. R.; Uberuaga, Blas P.

    2016-02-06

    Here, the surface structure of complex oxides plays a vital role in processes such as sintering, thin film growth, and catalysis, as well as being a critical factor determining the stability of nanoparticles. We report atomistic calculations of the low-index stoichiometric magnesium aluminate spinel (MgAl2O4) surfaces, each with two different chemical terminations. High temperature annealing was used to explore the potential energy landscape and provide more stable surface structures. We find that the lowest energy surface is {100} while the highest energy surface is {111}. The surfaces were subsequently doped with three trivalent dopants (Y3+, Gd3+, La3+) and one tetravalent dopant (Zr4+) and both the surface segregation energies of the dopants and surface energies of the doped surface were determined. All of the dopants reduce the surface energy of spinel, though this reduction in energy depends on both the size and valence of the dopant. Dopants with larger ionic radius tend to segregate to the surface more strongly and reduce the surface energy to a greater extent. Furthermore, the ionic valence of the dopants seems to have a stronger influence on the segregation than does ionic size. For both undoped and doped spinel, the predicted crystal shape is dominated by {100} surfaces, but the relative fraction of the various surfaces changes with doping due to the unequal changes in energy, which has implications on equilibrium nanoparticle shapes and therefore on applications sensitive to surface properties.

  16. IR spectroscopic determination of OH defects in spinel group minerals

    NASA Astrophysics Data System (ADS)

    Halmer, M. M.; Libowitzky, E.; Beran, A.

    2003-04-01

    Previous experimental studies showed that spinel phases, likely to occur in the transition zone of the Earth's mantle, contain essential amounts of water in form of OH groups. The g-Mg_2SiO_4 phase is reported to contain 27000 wt.ppm H_2O. The corresponding IR spectrum shows very broad absorption bands centered at 3645 and 3345cm-1 with a shoulder at 3120cm-1 (Kohlstedt et al., 1996). Thus, it is evident that under high-pressure conditions the spinel structure is capable to incorporate OH groups. Up to present, hydrogen contents of spinels from upper Earth's mantle and from crustal occurrences have not been reported in the literature. It is the aim of this study to prove the presence of OH defects in spinels of naturally occurring paragenesis and to develop some ideas on the structural incorporation mode based on promising results obtained from synthetic phases. Highly disordered non-stoichiometric Verneuil-grown MgAl spinels are characterized by two significant bands centered at 3355cm-1 and 3510cm-1, which show variations in band intensities. Synthetic H_ high-temperature treated intermediate compounds in the spinel-magnesioferrite (MgFe_2O_4), spinel-hercynite (FeAl2O4) and spinel-franklinite (ZnFe2O4) system from Andreozzi et al. (2001) indicate variable behavior. Whereas some of the spectra, which may be also correlated to d-d transitions of IVFe2+ (Skogby and Halenius, 2003) show broad absorptions in the 3500-3100cm-1 range, a pure MgAl2O4 end member sample is characterized by a rather sharp mode at 3450cm-1. Naturally occurring gahnite crystals (ZnAl2O_4) show significantly broad absorption band at 3400cm-1, which resembles some of the bands of the former synthetic samples. Based on the calibration of Libowitzky and Rossman (1997) the analytical H_2O content of the natural gahnite sample was determined to 580 wt.ppm. The position of the absorption bands implies weak hydrogen bonding of the OH defects in the spinel structure. This work was partly supported by

  17. Untangling the History of Oceanic Peridotites Using Spinel Oxybarometry

    NASA Astrophysics Data System (ADS)

    Birner, S.; Warren, J. M.; Cottrell, E.; Davis, F. A.

    2014-12-01

    Comprehensive knowledge of the oxygen fugacity of the upper mantle is critical to understanding the processes associated with melt production, interaction, and extraction. Thus, it is important to understand how fO2 changes during a peridotite's thermal and petrologic history in the asthenospheric and lithospheric mantle, as metamorphic subsolidus reequilibration can result in changes to recorded fO2. A case study of Tongan forearc peridotites highlights the heterogeneity seen in mantle peridotites. We analyzed two dredges located 250 km apart along the trench: one dredge ranges in fO2 from 0.5 to 1 log unit above the QFM buffer, similar to analyses of supra-subduction zone xenoliths (e.g. Brandon and Draper, 1996; Wood and Virgo, 1989) while the other dredge ranges from QFM-0.75 to QFM+0.25 and exhibits high spinel Cr# (ranging from 0.45 to 0.75). Systematics between fO2, Ti concentration, olivine forsterite content, and Cr# within each dredge allow us to differentiate between the effects of melt extraction, melt interaction, and cooling. Because the spinel oxybarometry equation is dependent on temperature, it is important to be able to accurately determine the temperature recorded by peridotites. Though many geothermometers are available for mantle rocks, we assert that geothermometers based on Fe-Mg exchange between olivine and spinel are the most applicable to fO2 calculations, because the oxygen fugacity recorded by a mantle assemblage is primarily controlled by this exchange. Additionally, preliminary analyses of diffusion profiles across olivine-spinel grain boundaries provide insight into the cooling of peridotite in the oceanic lithosphere and its effects on oxygen fugacity. Mg-Fe exchange between olivine and spinel is controlled by the distribution coefficient, KD, which is dependent on both temperature and the proportion of Cr to other trivalent cations in spinel. We see an increase in olivine forsterite content towards the olivine-spinel interface

  18. High Strength and Thermally Stable Nanostructured Magnesium Alloys and Nanocomposites

    NASA Astrophysics Data System (ADS)

    Chang, Yuan-Wei

    Magnesium and its alloys are currently in the spotlight of global research because of the need to limit energy consumption and reduce the environmental impact. In particular, their low densities compared to other structural metals make them a very attractive alternative in the automobile and aerospace industries. However, their low strength compared to other structural materials (e.g. Al and steels) has limited their widespread application. This dissertation presents the results of developing and investigation of a high strength nanostructured magnesium-aluminum alloy and composite. The nanostructured magnesium alloy is prepared by cryomilling and consolidated by spark-plasma-sintering. Focused ion beam is used to prepare micropillars with different diameters ranging from 1.5 to 8 mum and micro-compression test is conducted by nanoindenter in order to evaluate the mechanical properties. The yield strength obtained in the present study is around three times higher than conventional magnesium alloys (120 MPa vs. 370 MPa). The yield strength of the nanostructured magnesium alloy is further improved through hot extrusion, resulting in a yield strength of 550 MPa and an ultimate strength of 580 MPa. The nanostructured magnesium alloy exhibits a strong size-dependence, and a significant improvement in strength is observed when the pillar diameter is reduced to below 3.5 mum. The deformation mechanisms of the compressed pillars were characterized using transmission electron microscopy. The size-induced strengthening is attributed to a less number of dislocation sources along with a higher activity of non-basal deformation mechanisms. We have also developed a high strength and thermally stable nanostructured magnesium composite by adding diamantane. A yield strength of 500 MPa is achieved, moreover, excellent thermal stability is demonstrated in the magnesium alloy containing diamantanes. The strength and grain size are thermally stable after annealing at 400°C for 100

  19. Micro-XANES Measurements on Experimental Spinels and the Oxidation State of Vanadium in Coexisting Spinel and Silicate Melt

    NASA Technical Reports Server (NTRS)

    Righter, K.; Sutton, S. R.; Newville, M.; Le. L.; Schwandt, C. S.

    2005-01-01

    Spinel can be a significant host phase for V which has multiple oxidation states V(sup 2+), V(sup 3+), V(sup 4+) or V(sup 5+) at oxygen fugacities relevant to natural systems. The magnitude of D(V) spinel/melt is known to be a function of composition, temperature and fO2, but the uncertainty of the oxidation state under the range of natural conditions has made elusive a thorough understanding of D(V) spinel/melt. For example, V(sup 3+) is likely to be stable in spinels, based on exchange with Al in experiments in the CaO-MgO-Al2O3-SiO2 system. On the other hand, it has been argued that V(sup 4+) will be stable across the range of natural oxygen fugacities in nature. In order to build on our previous work in more oxidized systems, we have carried out experiments at relatively reducing conditions from the FMQ buffer to 2 log fO2 units below the IW buffer. These spinel-melt pairs, where V is present in the spinel at natural levels (approx. 300 ppm V), were analyzed using an electron microprobe at NASA-JSC and micro- XANES at the Advanced Photon Source at Argonne National Laboratory. The new results will be used together with previous results to understand the valence of V in spinel-melt systems across 12 orders of magnitude of oxygen fugacity, and with application to natural systems.

  20. Corrosion of aluminum and aluminum alloys

    SciTech Connect

    Davis, J.R.

    1999-01-01

    This new handbook presents comprehensive coverage of the corrosion behavior of aluminum and aluminum alloys, with emphasis on practical information about how to select and process these materials in order to prevent corrosion attack. Described are the characteristics of these materials and the influences of composition, mechanical working, heat treatment, joining methods, microstructure, and environmental variables on their corrosion.

  1. Constraining magnesium cycling in marine sediments using magnesium isotopes

    NASA Astrophysics Data System (ADS)

    Higgins, J. A.; Schrag, D. P.

    2010-09-01

    Magnesium concentrations in deep-sea sediment pore-fluids typically decrease down core due to net precipitation of dolomite or clay minerals in the sediments or underlying crust. To better characterize and differentiate these processes, we have measured magnesium isotopes in pore-fluids and sediment samples from Ocean Drilling Program sites (1082, 1086, 1012, 984, 1219, and 925) that span a range of oceanographic settings. At all sites, magnesium concentrations decrease with depth. At sites where diagenetic reactions are dominated by the respiration of organic carbon, pore-fluid δ 26Mg values increase with depth by as much as 2‰. Because carbonates preferentially incorporate 24Mg (low δ 26Mg), the increase in pore-fluid δ 26Mg values at these sites is consistent with the removal of magnesium in Mg-carbonate (dolomite). In contrast, at sites where the respiration of organic carbon is not important and/or weatherable minerals are abundant, pore-fluid δ 26Mg values decrease with depth by up to 2‰. The decline in pore-fluid δ 26Mg at these sites is consistent with a magnesium sink that is isotopically enriched relative to the pore-fluid. The identity of this enriched magnesium sink is likely clay minerals. Using a simple 1D diffusion-advection-reaction model of pore-fluid magnesium, we estimate rates of net magnesium uptake/removal and associated net magnesium isotope fractionation factors for sources and sinks at all sites. Independent estimates of magnesium isotope fractionation during dolomite precipitation from measured δ 26Mg values of dolomite samples from sites 1082 and 1012 are very similar to modeled net fractionation factors at these sites, suggesting that local exchange of magnesium between sediment and pore-fluid at these sites can be neglected. Our results indicate that the magnesium incorporated in dolomite is 2.0-2.7‰ depleted in δ 26Mg relative to the precipitating fluid. Assuming local exchange of magnesium is minor at the rest of the

  2. Magnesium fluoride recovery method

    DOEpatents

    Gay, Richard L.; McKenzie, Donald E.

    1989-01-01

    A method of obtaining magnesium fluoride substantially free from radioactive uranium from a slag containing the same and having a radioactivity level of at least about 7000 pCi/gm. The slag is ground to a particle size of about 200 microns or less. The ground slag is contacted with an acid under certain prescribed conditions to produce a liquid product and a particulate solid product. The particulate solid product is separated from the liquid and treated at least two more times with acid to produce a solid residue consisting essentially of magnesium fluoride substantially free of uranium and having a residual radioactivity level of less than about 1000 pCi/gm. In accordance with a particularly preferred embodiment of the invention a catalyst and an oxidizing agent are used during the acid treatment and preferably the acid is sulfuric acid having a strength of about 1.0 Normal.

  3. Determination of micro amounts of iron, aluminum, and alkaline earth metals in silicon carbide

    NASA Technical Reports Server (NTRS)

    Hirata, H.; Arai, M.

    1978-01-01

    A colorimetric method for analysis of micro components in silicon carbide used as the raw material for varistors is described. The microcomponents analyzed included iron soluble in hydrochloric acid, iron, aluminum, calcium and magnesium. Samples were analyzed by the method, and the results for iron and aluminum agreed well with the N.B.S. standard values and the values obtained by the other company. The method can therefore be applied to the analysis of actual samples.

  4. Investigation of the Microstructure of Joints of Aluminum Alloys Produced by Friction Stir Welding

    NASA Astrophysics Data System (ADS)

    Kolubaev, E. A.

    2015-02-01

    Special features of the microstructure of joints of aluminum-magnesium and aluminum-copper alloys produced by friction stir welding are analyzed. It is demonstrated that a layered structure with ultradisperse grains is produced by friction stir welding at the center of the weld joint. An analogy is drawn between the microstructures of joints produced by friction stir welding and surface layer produced by sliding friction.

  5. ALUMINUM-CONTAINING POLYMERS

    DTIC Science & Technology

    ALUMINUM COMPOUNDS, *ORGANOMETALLIC COMPOUNDS, *POLYMERIZATION, *POLYMERS, ACRYLIC RESINS, ALKYL RADICALS, CARBOXYLIC ACIDS, COPOLYMERIZATION, LIGHT TRANSMISSION, STABILITY, STYRENES, TRANSPARENT PANELS.

  6. Magnesium in Prevention and Therapy.

    PubMed

    Gröber, Uwe; Schmidt, Joachim; Kisters, Klaus

    2015-09-23

    Magnesium is the fourth most abundant mineral in the body. It has been recognized as a cofactor for more than 300 enzymatic reactions, where it is crucial for adenosine triphosphate (ATP) metabolism. Magnesium is required for DNA and RNA synthesis, reproduction, and protein synthesis. Moreover, magnesium is essential for the regulation of muscular contraction, blood pressure, insulin metabolism, cardiac excitability, vasomotor tone, nerve transmission and neuromuscular conduction. Imbalances in magnesium status-primarily hypomagnesemia as it is seen more common than hypermagnesemia-might result in unwanted neuromuscular, cardiac or nervous disorders. Based on magnesium's many functions within the human body, it plays an important role in prevention and treatment of many diseases. Low levels of magnesium have been associated with a number of chronic diseases, such as Alzheimer's disease, insulin resistance and type-2 diabetes mellitus, hypertension, cardiovascular disease (e.g., stroke), migraine headaches, and attention deficit hyperactivity disorder (ADHD).

  7. Aluminum and Young Artists.

    ERIC Educational Resources Information Center

    Anderson, Thomas

    1980-01-01

    The author suggests a variety of ways in which aluminum and aluminum foil can be used in elementary and junior high art classes: relief drawing and rubbing; printing; repousse; sculpture; mobiles; foil sculpture; and three dimensional design. Sources of aluminum supplies are suggested. (SJL)

  8. Potential automotive uses of wrought magnesium alloys

    SciTech Connect

    Gaines, L.; Cuenca, R.; Wu, S.; Stodolsky, F. |

    1996-06-01

    Vehicle weight reduction is one of the major means available to improve automotive fuel efficiency. High-strength steels, aluminum (Al), and polymers are already being used to reduce weight significantly, but substantial additional reductions could be achieved by greater use of low-density magnesium (Mg) and its alloys. Mg alloys are currently used in relatively small quantities for auto parts, generally limited to die castings (e.g., housings). Argonne National Laboratory`s Center for Transportation Research has performed a study for the Lightweight Materials Program within DOE`s Office of Transportation Materials to evaluate the suitability of wrought Mg and its alloys to replace steel/aluminum for automotive structural and sheet applications. Mg sheet could be used in body nonstructural and semi-structural applications, while extrusions could be used in such structural applications as spaceframes. This study identifies high cost as the major barrier to greatly increased Mg use in autos. Two technical R and D areas, novel reduction technology and better hot-forming technology, could enable major cost reductions.

  9. Preparation and characterization of lithium manganese oxide cubic spinel Li 1.03Mn 1.97O 4 doped with Mg and Fe

    NASA Astrophysics Data System (ADS)

    Singh, Priti; Sil, Anjan; Nath, Mala; Ray, Subrata

    2010-01-01

    Spinel powders of Li 1.03Mn 1.97O 4, Li 1.03[Mg xMn 1.97-x]O 4, Li 1.03[Fe yMn 1.97-y]O 4 and Li 1.03[Mg xFe yMn 1.97-x-y]O 4 systems were synthesized by sol-gel technique using lithium acetate, manganese acetate, magnesium acetate, iron nitrate and citric acid as the starting materials. The effect of Mg and Fe substitutions on the structure and surface morphology of spinel Li 1.03Mn 1.97O 4 has been examined by X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM) and Infrared spectroscopy (IR). Electrochemical characteristics such as the cyclic performance was also investigated. The materials for all the compositions exhibit a phase pure cubic spinel structure as evident from the XRD analyses. The crystallinity and average particle size of the material increases by doping with Fe and Mg. The particles of doped samples have truncated octahedral shape. The discharge capacity of Li 1.03Mn 1.97O 4 is 126 mAh/g. The doping increases cyclability; however, the discharge capacity reduces.

  10. Low brain magnesium in migraine

    SciTech Connect

    Ramadan, N.M.; Halvorson, H.; Vande-Linde, A.; Levine, S.R.; Helpern, J.A.; Welch, K.M.

    1989-10-01

    Brain magnesium was measured in migraine patients and control subjects using in vivo 31-Phosphorus Nuclear Magnetic Resonance Spectroscopy. pMg and pH were calculated from the chemical shifts between Pi, PCr and ATP signals. Magnesium levels were low during a migraine attack without changes in pH. We hypothesize that low brain magnesium is an important factor in the mechanism of the migraine attack.

  11. A Life Cycle Assessment of a Magnesium Automotive Front End

    SciTech Connect

    Das, Sujit; Dubreuil, Alain; Bushi, Lindita; Tharumarajah, Ambalavanar

    2009-01-01

    The Magnesium Front End Research and Development (MFERD) project under the sponsorship of Canada, China and USA aims to develop key technologies and a knowledge base for increased use of magnesium in automobile. The goal of this life cycle assessment (LCA) study is to compare the energy and potential environmental impacts of advanced magnesium based front end parts of a North America built 2007 GM-Cadillac CTS with the standard carbon steel based design. This LCA uses the 'cradle-to-grave' approach by including primary material production, semi-fabrication production, autoparts manufacturing and assembly, transportation, use phase and end-of-life processing of autoparts. This LCA study was done in compliance with international standards ISO 14040:2006 and ISO 14044:2006. Furthermore, the LCA results for aluminum based front end autopart are presented. While weight savings result in reductions in energy use and carbon dioxide emissions during the use of the car, the impacts of fabrication and recycling of lightweight materials are substantial in regard to steel. Pathways for improving sustainability of magnesium use in automobiles through material management and technology improvements including recycling are also discussed.

  12. The Morphology and Composition of Groundmass Spinel in Kimberlite

    NASA Astrophysics Data System (ADS)

    Roeder, P. L.

    2003-12-01

    Chromite and chromian spinel are a common, but very minor (<1%), early phase found in the groundmass of both basalt and kimberlite. The spinel is often zoned from a chromite core to a magnetite rim depending on the original melt composition, cooling rate and the nucleation of surrounding minerals. The primary silicate minerals in many kimberlites are often destroyed by late-stage alteration leaving spinel as one of the few minerals that retains morphological and chemical evidence of the progression from an early magmatic stage to a late-stage subsolidus alteration. The composition of basaltic and kimberlitic spinel can be compared by plotting FE2#(Fe2/(Fe2+Mg)) versus FE3#(Fe3/(Fe3+Al+Cr)). The primary chromite in both basalt and kimberlite usually have FE3# <0.15 and FE2# = 0.2-0.6 whereas the late stage magnetite for both rock types is high in FE3# and FE2#. Most spinel in basalts show a consistent trend of increasing FE2# with increasing FE3# whereas kimberlitic spinel can show a variety of different trends of increasing FE3# at a constant, or even decreasing, FE2#. Evidence will be presented that suggests that trends of FE3# vs. FE2# of spinel in various kimberlites may reflect variations in cooling rate of the kimberlite. It is useful to consider the morphology and compositional variation of spinel in kimberlite in terms of four stages: 1) High Cr2O3, TiO2<1 wt.%, FE2# < 0.5, FE3# <0.1. 2) High Cr2O3, TiO2 1-3 wt.%, FE2# <0.5, FE3# <0.1. 3) Cr2O3 1-50wt.%, TiO2 3-20 wt.%, FE2# 0.4-0.9, FE3# 0.1-0.9. 4) Cr2O3 <1 wt.%, TiO2 <2 wt.%, FE2# >0.8, FE3#>0.9 . The chromite of stage 1 reflects the bulk melt composition well before intrusion of the kimberlite whereas stage 2 is thought to reflect the relatively rapid and local change in melt composition during intrusion . Stage 3 reflects a very large change in composition due to very local crystallization of the groundmass minerals and diffusion-controlled crystallization that gives rise to atoll spinels. Stage 4

  13. Elastic stability of high dose neutron irradiated spinel

    SciTech Connect

    Li, Z.; Chan, S.K.; Garner, F.A.

    1995-04-01

    The objective of this effort is to identify ceramic materials that are suitable for fusion reactor applications. Elastic constants (C{sub 11}, C{sub 12}, and C{sub 44}) of spinel (MgAl{sub 2}O{sub 4}) single crystals irradiated to very high neutron fluences have geen measured by an ultrasonic technique. Although results of a neutron diffraction study show that cation occupation sites are significantly changed in the irradiated samples, no measurable differences occurred in their elastic properties. In order to understand such behavior, the elastic properties of a variety of materials with either normal or inverse spinel structures were studied. The cation valence and cation distribution appear to have little influence on the elastic properties of spinel materials.

  14. Aluminum reference electrode

    DOEpatents

    Sadoway, D.R.

    1988-08-16

    A stable reference electrode is described for use in monitoring and controlling the process of electrolytic reduction of a metal. In the case of Hall cell reduction of aluminum, the reference electrode comprises a pool of molten aluminum and a solution of molten cryolite, Na[sub 3]AlF[sub 6], wherein the electrical connection to the molten aluminum does not contact the highly corrosive molten salt solution. This is accomplished by altering the density of either the aluminum (decreasing the density) or the electrolyte (increasing the density) so that the aluminum floats on top of the molten salt solution. 1 fig.

  15. Aluminum reference electrode

    DOEpatents

    Sadoway, Donald R.

    1988-01-01

    A stable reference electrode for use in monitoring and controlling the process of electrolytic reduction of a metal. In the case of Hall cell reduction of aluminum, the reference electrode comprises a pool of molten aluminum and a solution of molten cryolite, Na.sub.3 AlF.sub.6, wherein the electrical connection to the molten aluminum does not contact the highly corrosive molten salt solution. This is accomplished by altering the density of either the aluminum (decreasing the density) or the electrolyte (increasing the density) so that the aluminum floats on top of the molten salt solution.

  16. Spinel troctolite and anorthosite in Apollo 16 samples.

    NASA Technical Reports Server (NTRS)

    Prinz, M.; Dowty, E.; Keil, K.; Bunch, T. E.

    1973-01-01

    Review of the examination results on two Apollo 16 rocks recovered from the lunar highlands which probably represent contrasting types of 'primitive' lunar cumulates. One is a microbreccia containing a large lithic fragment of spinel troctolite, while the other is a shock-brecciated anorthosite. The reviewed results suggest that, if the two rock groups formed from the same parent magma type, the spinel troctolite must have formed early in the differentiation sequence as the result of crystal settling in the melt, whereas the anorthosite must have formed as a later cumulate, possibly by flotation.

  17. Cation disorder in high-dose, neutron-irradiated spinel

    SciTech Connect

    Sickafus, K.E.; Larson, A.C.; Yu, N.

    1995-04-01

    The objective of this effort is to determine whether MgAl{sub 2}O{sub 4} spinel is a suitable ceramic for fusion applications. The crystal structures of MgAl{sub 2}O{sub 4} spinel single crystals irradiated to high neutron fluences [>5{times}10{sup 26} n/m{sup 2} (E{sub n}>0.1 MeV)] were examined by neutron diffraction. Crystal structure refinement of the highese dose sample indicated that the average scattering strength of the tetrahedral crystal sites decreased by {approx}20% while increasing by {approx}8% on octahedral sites.

  18. [Magnesium disorder in metabolic bone diseases].

    PubMed

    Ishii, Akira; Imanishi, Yasuo

    2012-08-01

    Magnesium is abundantly distributed among the body. The half of the magnesium exists in the bone. In addition, magnesium is the second most abundant intracellular cation in vertebrates and essential for maintaining physiological function of the cells. Epidemiologic studies have demonstrated that magnesium deficiency is a risk factor for osteoporosis. The mechanism of bone fragility caused by magnesium deficiency has been intensely studied using animal models of magnesium deficiency. Magnesium deficiency causes decreased osteoblastic function and increased number of osteoclasts. Magnesium deficiency also accelerates mineralization in bone. These observations suggest that disturbed bone metabolic turnover and mineralization causes bone fragility.

  19. A Nonlinear Thermomechanical Model of Spinel Ceramics Applied to Aluminum Oxynitride (AlON)

    DTIC Science & Technology

    2011-01-01

    that strain hardening ceases above some saturation stress 29,44,45; however, from the preceding argu- ments, it may be reasonable to assume that during...Microdamage in Polycrystalline Ceramics Under Dynamic Compression and Tension,” J. Appl. Phys., 98, p. 023505. 15 Kraft , R. H., Molinari, J. F., Ramesh, K...D DANDEKAR M GREENFIELD C HOPPEL R KRAFT R LEAVY B LOVE M RAFTENBERG T WEERASOORIYA C WILLIAMS RDRL WMP C

  20. Partitioning of Ni, Co and V between Spinel-Structured Oxides and Silicate Melts: Importance of Spinel Composition

    NASA Technical Reports Server (NTRS)

    Righter, K.; Leeman, W. P.; Hervig, R. L.

    2006-01-01

    Partitioning of Ni, Co and V between Cr-rich spinels and basaltic melt has been studied experimentally between 1150 and 1325 C, and at controlled oxygen fugacity from the Co-CoO buffer to slightly above the hematite magnetite buffer. These new results, together with new Ni, Co and V analyses of experimental run products from Leeman [Leeman, W.P., 1974. Experimental determination of the partitioning of divalent cations between olivine and basaltic liquid, Pt. II. PhD thesis, Univ. Oregon, 231 - 337.], show that experimentally determined spinel melt partition coefficients (D) are dependent upon temperature (T), oxygen fugacity (fO2) and spinel composition. In particular, partition coefficients determined on doped systems are higher than those in natural (undoped) systems, perhaps due to changing activity coefficients over the composition range defined by the experimental data. Using our new results and published runs (n =85), we obtain a multilinear regression equation that predicts experimental D(V) values as a function of T, fO2, concentration of V in melt and spinel composition. This equation allows prediction of D(V) spinel/melt values for natural mafic liquids at relevant crystallization conditions. Similarly, D(Ni) and D(Co) values can be inferred from our experiments at redox conditions approaching the QFM buffer, temperatures of 1150 to 1250 C and spinel composition (early Cr-bearing and later Ti-magnetite) appropriate for basic magma differentiation. When coupled with major element modelling of liquid lines of descent, these values (D(Ni) sp/melt=10 and D(Co) sp/melt=5) closely reproduce the compositional variation observed in komatiite, mid-ocean ridge basalt (MORB), ocean island basalt (OIB) and basalt to rhyolite suites.

  1. MAGNESIUM MONO POTASSIUM PHOSPHATE GROUT FOR P-REACTOR VESSEL IN-SITU DECOMISSIONING

    SciTech Connect

    Langton, C.; Stefanko, D.

    2011-01-05

    The objective of this report is to document laboratory testing of magnesium mono potassium phosphate grouts for P-Reactor vessel in-situ decommissioning. Magnesium mono potassium phosphate cement-based grout was identified as candidate material for filling (physically stabilizing) the 105-P Reactor vessel (RV) because it is less alkaline than portland cement-based grout (pH of about 12.4). A less alkaline material ({<=} 10.5) was desired to address a potential materials compatibility issue caused by corrosion of aluminum metal in highly alkaline environments such as that encountered in portland cement grouts. Information concerning access points into the P-Reactor vessel and amount of aluminum metal in the vessel is provided elsewhere. Fresh and cured properties were measured for: (1) commercially blended magnesium mono potassium phosphate packaged grouts, (2) commercially available binders blended with inert fillers at SRNL, (3) grouts prepared from technical grade MgO and KH{sub 2}PO{sub 4} and inert fillers (quartz sands, Class F fly ash), and (4) Ceramicrete{reg_sign} magnesium mono potassium phosphate-based grouts prepared at Argonne National Laboratory. Boric acid was evaluated as a set retarder in the magnesium mono potassium phosphate mixes.

  2. Magnesium Hall Thruster

    NASA Technical Reports Server (NTRS)

    Szabo, James J.

    2015-01-01

    This Phase II project is developing a magnesium (Mg) Hall effect thruster system that would open the door for in situ resource utilization (ISRU)-based solar system exploration. Magnesium is light and easy to ionize. For a Mars- Earth transfer, the propellant mass savings with respect to a xenon Hall effect thruster (HET) system are enormous. Magnesium also can be combusted in a rocket with carbon dioxide (CO2) or water (H2O), enabling a multimode propulsion system with propellant sharing and ISRU. In the near term, CO2 and H2O would be collected in situ on Mars or the moon. In the far term, Mg itself would be collected from Martian and lunar regolith. In Phase I, an integrated, medium-power (1- to 3-kW) Mg HET system was developed and tested. Controlled, steady operation at constant voltage and power was demonstrated. Preliminary measurements indicate a specific impulse (Isp) greater than 4,000 s was achieved at a discharge potential of 400 V. The feasibility of delivering fluidized Mg powder to a medium- or high-power thruster also was demonstrated. Phase II of the project evaluated the performance of an integrated, highpower Mg Hall thruster system in a relevant space environment. Researchers improved the medium power thruster system and characterized it in detail. Researchers also designed and built a high-power (8- to 20-kW) Mg HET. A fluidized powder feed system supporting the high-power thruster was built and delivered to Busek Company, Inc.

  3. Magnesium reduction of uranium oxide

    SciTech Connect

    Elliott, G.R.B.

    1985-08-13

    A method and apparatus are provided for reducing uranium oxide with magnesium to form uranium metal. The reduction is carried out in a molten-salt solution of density greater than 3.4 grams per cubic centimeter, thereby allowing the uranium product to sink and the magnesium oxide byproduct to float, consequently allowing separation of product and byproduct.

  4. Aluminum: Recycling of Aluminum Dross/Saltcake

    SciTech Connect

    Blazek, S.

    1999-01-29

    As this NICE3 publication details, the objective of this project is to commercialize the process technology to eliminate all landfill waste associated with black dross and saltcake generated from aluminum recycling in the United States.

  5. Magnesium substitution in brushite cements.

    PubMed

    Alkhraisat, Mohammad Hamdan; Cabrejos-Azama, Jatsue; Rodríguez, Carmen Rueda; Jerez, Luis Blanco; Cabarcos, Enrique López

    2013-01-01

    The use of magnesium-doped ceramics has been described to modify brushite cements and improve their biological behavior. However, few studies have analyzed the efficiency of this approach to induce magnesium substitution in brushite crystals. Mg-doped ceramics composed of Mg-substituted β-TCP, stanfieldite and/or farringtonite were reacted with primary monocalcium phosphate (MCP) in the presence of water. The cement setting reaction has resulted in the formation of brushite and newberyite within the cement matrix. Interestingly, the combination of SAED and EDX analyses of single crystal has indicated the occurrence of magnesium substitution within brushite crystals. Moreover, the effect of magnesium ions on the structure, and mechanical and setting properties of the new cements was characterized as well as the release of Ca(2+) and Mg(2+) ions. Further research would enhance the efficiency of the system to incorporate larger amounts of magnesium ions within brushite crystals.

  6. Magnesium in Prevention and Therapy

    PubMed Central

    Gröber, Uwe; Schmidt, Joachim; Kisters, Klaus

    2015-01-01

    Magnesium is the fourth most abundant mineral in the body. It has been recognized as a cofactor for more than 300 enzymatic reactions, where it is crucial for adenosine triphosphate (ATP) metabolism. Magnesium is required for DNA and RNA synthesis, reproduction, and protein synthesis. Moreover, magnesium is essential for the regulation of muscular contraction, blood pressure, insulin metabolism, cardiac excitability, vasomotor tone, nerve transmission and neuromuscular conduction. Imbalances in magnesium status—primarily hypomagnesemia as it is seen more common than hypermagnesemia—might result in unwanted neuromuscular, cardiac or nervous disorders. Based on magnesium’s many functions within the human body, it plays an important role in prevention and treatment of many diseases. Low levels of magnesium have been associated with a number of chronic diseases, such as Alzheimer’s disease, insulin resistance and type-2 diabetes mellitus, hypertension, cardiovascular disease (e.g., stroke), migraine headaches, and attention deficit hyperactivity disorder (ADHD). PMID:26404370

  7. The Role of Stress in the Corrosion Cracking of Aluminum Alloys

    DTIC Science & Technology

    2013-03-01

    50 Figure 42. Crack Orientations for Rolled Plate Material . From [18] ................................53 xi LIST OF TABLES...Increasing transverse stability allows the ship to be operated in higher sea states that would normally prohibit the safe operation of the ship. This...alloying addition in 5000 series aluminum is magnesium, which gives the material good specific strength and general corrosion properties and is also

  8. Effect of aging on mechanical properties of aluminum-alloy rivets

    NASA Technical Reports Server (NTRS)

    Roop, Frederick C

    1941-01-01

    Curves and tabular data present the results of strength tests made during and after 2 1/2 years of aging on rivets and rivet wire of 3/16-inch nominal diameter. The specimens were of aluminum alloy: 24s, 17s, and a17s of the duralumin type and 53s of the magnesium-silicide type.

  9. Effect of aging on mechanical properties of aluminum-alloy rivets

    NASA Technical Reports Server (NTRS)

    Roop, Frederick C

    1941-01-01

    Curves and tabular data present the results of strength tests made during and after 2 1/2 years of aging on rivets and rivet wire of 3/16-inch nominal diameter. The specimens were of aluminum alloy: 24S, 17S, and A17S of the duralumin type and 53S of the magnesium-silicide type.

  10. Al and Zn Impurity Diffusion in Binary and Ternary Magnesium Solid-Solutions

    SciTech Connect

    Kammerer, Catherine; Kulkarni, Nagraj S; Warmack, Robert J Bruce; Sohn, Yong Ho

    2014-01-01

    Magnesium alloys are considered for implementation into structural components where energy-efficiency and light-weighting are important. Two of the most common alloying elements in magnesium alloys are Aluminum and Zinc. The present work examines impurity diffusion coefficients of Al and Zn in Mg(Zn) and Mg(Al) binary solid solutions, respectively. Experimental investigation is carried out with ternary diffusion couples with polycrystalline alloys. Concentration profiles were measured by electron microprobe micro-analysis and the impurity diffusion coefficients were determined by the Hall Method. Results of Al and Zn impurity diffusion in Mg solid solutions are reported, and examined as a function of composition of Mg solid solution.

  11. Spinel troctolite and anorthosite in apollo 16 samples.

    PubMed

    Prinz, M; Dowty, E; Keil, K; Bunch, T E

    1973-01-05

    A spinel troctolite and an anorthosite from the Apollo 16 landing site represent contrasting types of "primitive" lunar cumulates. The two rock types probably formed from the same parent magma type, a high-alumina magnesian basalt, with the troctolite forming earlier by crystal settling, and the anorthosite later, possibly by flotation.

  12. Subsurface Optical Microscopy of Coarse Grain Spinels. Phase 1

    DTIC Science & Technology

    2013-12-01

    A 456 nm LED line bar illuminated in figure 15 and a Xenon fiber optic bar illuminator is shown for figure 16. The optical in situ or subsurface ... imaging of coarse grain spinels and AlONs is optically more complex than expected. An overhead view of the side illumination field is shown in figure 20

  13. Investigation of High-Temperature Slag/Copper/Spinel Interactions

    NASA Astrophysics Data System (ADS)

    De Wilde, Evelien; Bellemans, Inge; Campforts, Mieke; Guo, Muxing; Blanpain, Bart; Moelans, Nele; Verbeken, Kim

    2016-12-01

    An important cause for the mechanical entrainment of copper droplets in slags during primary and secondary copper production is their interaction with solid spinel particles, hindering the sedimentation of the copper droplets. In the present study, the interactions between the three phases involved (slag-Cu droplets-spinel solids) were investigated using an adapted sessile drop experiment, combined with detailed microstructural investigation of the interaction zone. An industrially relevant synthetic PbO-CaO-SiO2-Cu2O-Al2O3-FeO-ZnO slag system, a MgAl2O4 spinel particle, and pure copper were examined with electron microscopy after their brief interaction at 1523 K (1250 °C). Based on the experimental results, a mechanism depending on the interlinked dissolved Cu and oxygen contents within the slag is proposed to describe the origin of the phenomenon of sticking Cu alloy droplets. In addition, the oxygen potential gradient across the phases ( i.e., liquid Cu, slag, and spinel) appears to affect the Cu entrainment, as deduced from a microstructural analysis.

  14. A transmission electron microscopy study of presolar spinel

    NASA Astrophysics Data System (ADS)

    Zega, Thomas J.; Nittler, Larry R.; Gyngard, Frank; Alexander, Conel M. O.'D.; Stroud, Rhonda M.; Zinner, Ernst K.

    2014-01-01

    We report on the isotopic and microstructural properties of four presolar spinel grains identified in acid-resistant residues of the Murray CM2 and Orgueil (ORG) CI1 chondrites, and a mixture of the unequilibrated ordinary chondrites (UOC) QUE 97008 (L3.05), WSG 95300 (H3.3), and MET00452 (LL3.05) collected in Antarctica. All four grains have O-isotopic compositions indicating an origin in low-mass (∼1.2-1.4 M⊙) O-rich asymptotic giant branch (AGB) stars, although two of the grains have compositions indicating that non-standard mixing (cool-bottom processing) likely occurred in their parent stars. Three of the grains are single-crystal Mg-Al-rich spinels containing minor Fe and Cr; one is Mg deficient and one contains minor Ca. The fourth consists of an assemblage of three, Fe-Cr-rich crystalline grains with closely aligned crystallographic orientation but systematically varied cation composition. Each spinel grain within the assemblage also contains Ti-rich sub-grains (<100 nm) whose lattice structures are coherent with their host crystals. Oxygen isotope measurements of the Orgueil residue identified four additional particles all with similar elemental and isotope composition. These are the first known presolar Fe-Cr-rich spinels. The isotopic and microstructural data indicate that the Al-Mg-rich and Fe-Cr-rich grains experienced different condensation and processing histories. The single-crystal, stoichiometric, nearly pure Mg-Al spinels are generally consistent with equilibrium condensation predictions, which constrain their condensation temperatures between 1161 and 1221 K, assuming total gas pressures of 1 × 10-6 and 1 × 10-3 atm, respectively. Minor stacking disorder is observed in one of the Mg-Al spinels and is probably a result of slight perturbations to crystal growth during condensation in the circumstellar environment or of impact-induced sheer strain as a response to grain-grain collisions, which could have occurred in the circumstellar

  15. Aspects of aluminum toxicity

    SciTech Connect

    Hewitt, C.D.; Savory, J.; Wills, M.R. )

    1990-06-01

    Aluminum is the most abundant metal in the earth's crust. The widespread occurrence of aluminum, both in the environment and in foodstuffs, makes it virtually impossible for man to avoid exposure to this metal ion. Attention was first drawn to the potential role of aluminum as a toxic metal over 50 years ago, but was dismissed as a toxic agent as recently as 15 years ago. The accumulation of aluminum, in some patients with chronic renal failure, is associated with the development of toxic phenomena; dialysis encephalopathy, osteomalacic dialysis osteodystrophy, and an anemia. Aluminum accumulation also occurs in patients who are not on dialysis, predominantly infants and children with immature or impaired renal function. Aluminum has also been implicated as a toxic agent in the etiology of Alzheimer's disease, Guamiam amyotrophic lateral sclerosis, and parkinsonism-dementia. 119 references.

  16. How Rich is Rich? Placing Constraints on the Abundance of Spinel in the Pink Spinel Anorthosite Lithology on the Moon Through Space Weathering

    NASA Technical Reports Server (NTRS)

    Gross, J.; Gillis-Davis, J.; Isaacson, P. J.; Le, L.

    2015-01-01

    previously unknown lunar rock was recently recognized in the Moon Mineralogy Mapper (M(sup 3)) visible to near-infrared (VNIR) reflectance spectra. The rock type is rich in Mg-Al spinel (approximately 30%) and plagioclase and contains less than 5% mafic silicate minerals (olivine and pyroxene). The identification of this pink spinel anorthosite (PSA) at the Moscoviense basin has sparked new interest in lunar spinel. Pieters et al. suggested that these PSA deposits might be an important component of the lunar crust. However, Mg-Al spinel is rare in the Apollo and meteorite sample collections (only up to a few wt%), and occurs mostly in troctolites and troctolitic cataclastites. In this study, we are conducting a series of experiments (petrologic and space weathering) to investigate whether deposits of spinel identified by remote sensing are in high concentration (e.g. 30%) or whether the concentrations of spinel in these deposits are more like lunar samples, which contain only a few wt%. To examine the possibility of an impact-melt origin for PSA, conducted 1-bar crystallization experiments on rock compositions similar to pink spinel troctolite 65785. The VNIR spectral reflectance analyses of the low-temperature experiments yield absorption features similar to those of the PSA lithology detected at Moscoviense Basin. The experimental run products at these temperatures contain approximately 5 wt% spinel, which suggests that the spinel-rich deposits detected by M(sup 3) might not be as spinel-rich as previously thought. However, the effect of space weathering on spinel is unknown and could significantly alter its spectral properties including potential weakening of its diagnostic 2-micrometers absorption feature. Thus, weathered lunar rocks could contain more spinel than a comparison with the unweathered experimental charges would suggest. In this study, we have initiated space weathering experiments on 1) pure pink spinel, 2) spinel-anorthite mixtures, and 3) the low

  17. 75 FR 20817 - Magnesium Metal from the People's Republic of China: Preliminary Results of the 2008-2009...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-21

    ... during the production of subject merchandise and reintroduced into the production process.\\40\\ However... practice of rejecting financial statements of surrogate producers whose production process or integration... production process for magnesium metal is similar to that of extruded aluminum products for purposes...

  18. Modeling of Spinel Settling in Waste Glass Melter

    SciTech Connect

    Hrma, Pavel R.; Nemec, Lubomir; Schill, Petr

    1999-06-01

    Each 1% increase of waste loading (W), defined as the high-level waste (HLW) mass fraction in glass, can save the U.S. Department of Energy (DOE) over a half billion U.S. dollars for vitrification and disposal. For a majority of Hanford and Savannah River waste streams, W is limited by spinel precipitation and settling in waste glass melters. Therefore, a fundamental understanding of spinel behavior is crucial for economy and the low-risk operation of HLW vitrification. The goal of this research is to develop a basic understanding of the dynamics of spinel formation and motion in velocity, temperature, and redox fields that are characteristic for the glass-melting process. This goal is being achieved by directly studying spinel formation and settling in molten glass and by developing a mathematical tool for predicting the spinel behavior and accumulation rate in the melter. The main potential benefit of this study is achieving a lower waste-glass volume, which translates into a shorter cleanup time, a smaller processing facility, a smaller repository space, and, hence, a reduced investment of time and money to reach acceptable technical risks. Additional benefits include (1) more accurately assessing sensible limits for problem constituents (such as chromium) in the melter feed, (2) reducing the blending requirements, and (3) comparing cost and risk with other options (pretreatment, blending or diluting the waste) to determine the best path forward. The results of this study will allow alternate melter designs and operating conditions to be evaluated. The study will also address the option of removing the settled sludge from the melter.

  19. Structure-dielectric properties relationships in copper-substituted magnesium ferrites

    SciTech Connect

    Druc, A.C.; Borhan, A.I.; Nedelcu, G.G.; Leontie, L.; Iordan, A.R.; Palamaru, M.N.

    2013-11-15

    Graphical abstract: - Highlights: • Synthesis of copper substituted magnesium ferrites materials is reported. • A shift from cubic to tetragonal structure starting with x = 0.84 was observed. • The dielectric properties are influenced by Cu-substitution. - Abstract: Nanocrystalline powders of copper-substituted magnesium ferrites with general formula Mg{sub 1−x}Cu{sub x}Fe{sub 2}O{sub 4} (x = 0.00, 0.17, 0.34, 0.50, 0.67, 0.84, 1.00) were prepared for the first time by sol–gel auto-combustion method, using glycine as fuel agent. Solid phase chemical reactions and the occurrence of spinel structure were monitored by using infrared spectroscopy. X-ray diffraction analysis confirmed the spinel single-phase formation. A shift from cubic structure to tetragonal structure starting with x = 0.84 was also observed. Microstructure of the samples was analyzed by scanning electron microscopy and particle size was estimated from the micrographs. Analysis of dielectric properties revealed very low values of dielectric loss at frequencies over 10 MHz.

  20. Removal of Inclusions from Molten Aluminum by Supergravity Filtration

    NASA Astrophysics Data System (ADS)

    Song, Gaoyang; Song, Bo; Yang, Zhanbing; Yang, Yuhou; Zhang, Jing

    2016-12-01

    A new approach to removing inclusions from aluminum melt by supergravity filtration was investigated. The molten aluminum containing MgAl2O4 spinel and coarse Al3Ti particles was isothermally filtered with different gravity coefficients, different filtering times, and various filtering temperatures under supergravity field. When the gravity coefficient G ≥ 50, the alloy samples were divided automatically into two parts: the upper residue and the lower filtered aluminum. All inclusions (MgAl2O4 and Al3Ti particles) were nearly intercepted in the upper residue by filter felt with average pore size of 44.78 μm. The removal efficiencies of oxide inclusions and Al3Ti particles exceeded 98 and 90 pct, respectively, at G ≥ 50, t = 2 minutes, T = 973 K (700 °C). Besides, the yield of purified aluminum was up to 92.1 pct at G = 600, t = 2 minutes, and T = 973 K (700 °C). The calculations of centrifugal pressure indicated that supergravity filtration could effectively overcome the pressure drop without meeting the rigorous requirement of height of molten metal, especially for using the fine-pore filter medium. Moreover, cake-mode filtration was the major mechanism of supergravity filtration of molten metal in this work.

  1. Fine Grain Aluminum Superplasticity

    DTIC Science & Technology

    1980-02-01

    time at elevated temperature for 7475 aluminum alloy 5 2 Optical micrographs of 7075 aluminum alloy after exposure to 5160C (960oF) for times...applied to Al-Zn-Mg-Cu ( 7075 Al) alloy. Subsequent developments by Waldman et al. (refs. 8-11) resulted in the demonstration that 7000 series alloys...a number of aluminum alloys. With such a fine grain structure, high temperature deformation character- istics approaching superplastic behavior

  2. BONDING ALUMINUM METALS

    DOEpatents

    Noland, R.A.; Walker, D.E.

    1961-06-13

    A process is given for bonding aluminum to aluminum. Silicon powder is applied to at least one of the two surfaces of the two elements to be bonded, the two elements are assembled and rubbed against each other at room temperature whereby any oxide film is ruptured by the silicon crystals in the interface; thereafter heat and pressure are applied whereby an aluminum-silicon alloy is formed, squeezed out from the interface together with any oxide film, and the elements are bonded.

  3. Aluminum powder metallurgy processing

    SciTech Connect

    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.

  4. Synthesis of magnesium diboride by magnesium vapor infiltration process (MVIP)

    DOEpatents

    Serquis, Adriana C.; Zhu, Yuntian T.; Mueller, Frederick M.; Peterson, Dean E.; Liao, Xiao Zhou

    2003-01-01

    A process of preparing superconducting magnesium diboride powder by heating an admixture of solid magnesium and amorphous boron powder or pellet under an inert atmosphere in a Mg:B ratio of greater than about 0.6:1 at temperatures and for time sufficient to form said superconducting magnesium diboride. The process can further include exposure to residual oxygen at high synthesis temperatures followed by slow cooling. In the cooling process oxygen atoms dissolved into MgB.sub.2 segregated to form nanometer-sized coherent Mg(B,O) precipitates in the MgB.sub.2 matrix, which can act as flux pinning centers.

  5. Processing Studies of Aluminum-Magnesium and Aluminum-Copper-Lithium Alloys

    DTIC Science & Technology

    1990-03-01

    mechanisim of microstructural refinement during processing. Most recently, Gorsuch has investigated the effects of varying the annealing time between...obtained during testing at 300°C [Ref 3]. A portion of this research will follow that of Gorsuch by extending the annealing interval to 60 minutes in...on an Al.10Mg.0.lZr(wt.pct) alloy wherein Gorsuch varied the annealing times between rolling passes. As the annealing times are increased from 5

  6. Dietary magnesium and urolithiasis in growing calves.

    PubMed

    Kallfelz, F A; Ahmed, A S; Wallace, R J; Sasangka, B H; Warner, R G

    1987-01-01

    The effect of high levels of dietary magnesium (1.4%) alone or in combination with elevated calcium (1.8%) or phosphorus (1.6%) on growth and health of male calves was evaluated during a nine week feeding trial after weaning. Twenty calves were randomly divided into 4 feeding groups consisting of controls, high magnesium, high magnesium and calcium or high magnesium and phosphorus. Elevated dietary minerals caused decreased feed intake and growth rate. Blood urea nitrogen and serum creatinine levels were greatly elevated in calves fed high magnesium or magnesium and phosphorus and serum urea nitrogen was moderately elevated in calves fed high magnesium and calcium. These elevations suggested the occurrence of renal damage as a result of microcrystalline obstruction of renal tubules. Serum magnesium levels were three times normal in calves fed high magnesium or magnesium and phosphorus, but only twice normal in calves fed high magnesium and calcium. High dietary magnesium resulted in a significant depression in blood calcium level. This effect was somewhat overcome by additional dietary calcium Three calves fed the high magnesium diet and two calves fed the high magnesium and phosphorus diet developed urinary tract obstruction. The chemical composition of uroliths recovered from these calves was calcium apatite. Elevated dietary magnesium has been shown to be a cause of urolithiasis in growing male calves. Additional dietary calcium, but not phosphorus, appears to protect calves against urolithiasis induced by elevated dietary magnesium.

  7. 21 CFR 184.1443 - Magnesium sulfate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Magnesium sulfate. 184.1443 Section 184.1443 Food... Specific Substances Affirmed as GRAS § 184.1443 Magnesium sulfate. (a) Magnesium sulfate (MgSO4·7H2O, CAS... magnesium oxide, hydroxide, or carbonate with sulfuric acid and evaporating the solution to...

  8. 21 CFR 184.1431 - Magnesium oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium oxide. 184.1431 Section 184.1431 Food and... Substances Affirmed as GRAS § 184.1431 Magnesium oxide. (a) Magnesium oxide (MgO, CAS Reg. No. 1309-48-4... powder (light) or a relatively dense white powder (heavy) by heating magnesium hydroxide or...

  9. 21 CFR 184.1426 - Magnesium chloride.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Magnesium chloride. 184.1426 Section 184.1426 Food... Specific Substances Affirmed as GRAS § 184.1426 Magnesium chloride. (a) Magnesium chloride (MgC12·6H2O, CAS... mineral bischofite. It is prepared by dissolving magnesium oxide, hydroxide, or carbonate in...

  10. Mineral resource of the month: magnesium

    USGS Publications Warehouse

    Kramer, Deborah A.

    2012-01-01

    Magnesium is the eighthmost abundant element in Earth’s crust, and the second-most abundant metal ion in seawater. Although magnesium is found in more than 60 minerals, only brucite, dolomite, magnesite and carnallite are commercially important for their magnesium content. Magnesium and its compounds also are recovered from seawater, brines found in lakes and wells, and bitterns (salts).

  11. 21 CFR 184.1431 - Magnesium oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Magnesium oxide. 184.1431 Section 184.1431 Food... Specific Substances Affirmed as GRAS § 184.1431 Magnesium oxide. (a) Magnesium oxide (MgO, CAS Reg. No... bulky white powder (light) or a relatively dense white powder (heavy) by heating magnesium hydroxide...

  12. 21 CFR 184.1426 - Magnesium chloride.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Magnesium chloride. 184.1426 Section 184.1426 Food... Specific Substances Affirmed as GRAS § 184.1426 Magnesium chloride. (a) Magnesium chloride (MgC12·6H2O, CAS... mineral bischofite. It is prepared by dissolving magnesium oxide, hydroxide, or carbonate in...

  13. 21 CFR 184.1443 - Magnesium sulfate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium sulfate. 184.1443 Section 184.1443 Food... Specific Substances Affirmed as GRAS § 184.1443 Magnesium sulfate. (a) Magnesium sulfate (MgSO4·7H2O, CAS... magnesium oxide, hydroxide, or carbonate with sulfuric acid and evaporating the solution to...

  14. 21 CFR 184.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium hydroxide. 184.1428 Section 184.1428 Food... Specific Substances Affirmed as GRAS § 184.1428 Magnesium hydroxide. (a) Magnesium hydroxide (Mg(OH)2, CAS... a white precipitate by the addition of sodium hydroxide to a water soluble magnesium salt or...

  15. 21 CFR 184.1443 - Magnesium sulfate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Magnesium sulfate. 184.1443 Section 184.1443 Food... Specific Substances Affirmed as GRAS § 184.1443 Magnesium sulfate. (a) Magnesium sulfate (MgSO4·7H2O, CAS... magnesium oxide, hydroxide, or carbonate with sulfuric acid and evaporating the solution to...

  16. 21 CFR 184.1426 - Magnesium chloride.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Magnesium chloride. 184.1426 Section 184.1426 Food... Specific Substances Affirmed as GRAS § 184.1426 Magnesium chloride. (a) Magnesium chloride (MgC12·6H2O, CAS... mineral bischofite. It is prepared by dissolving magnesium oxide, hydroxide, or carbonate in...

  17. 21 CFR 184.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Magnesium hydroxide. 184.1428 Section 184.1428... GRAS § 184.1428 Magnesium hydroxide. (a) Magnesium hydroxide (Mg(OH)2, CAS Reg. No. 1309-42-8) occurs... addition of sodium hydroxide to a water soluble magnesium salt or by hydration of reactive grades...

  18. 21 CFR 184.1431 - Magnesium oxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Magnesium oxide. 184.1431 Section 184.1431 Food... Specific Substances Affirmed as GRAS § 184.1431 Magnesium oxide. (a) Magnesium oxide (MgO, CAS Reg. No... bulky white powder (light) or a relatively dense white powder (heavy) by heating magnesium hydroxide...

  19. 21 CFR 184.1443 - Magnesium sulfate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Magnesium sulfate. 184.1443 Section 184.1443 Food... Specific Substances Affirmed as GRAS § 184.1443 Magnesium sulfate. (a) Magnesium sulfate (MgSO4·7H2O, CAS... magnesium oxide, hydroxide, or carbonate with sulfuric acid and evaporating the solution to...

  20. 21 CFR 184.1426 - Magnesium chloride.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium chloride. 184.1426 Section 184.1426 Food... Specific Substances Affirmed as GRAS § 184.1426 Magnesium chloride. (a) Magnesium chloride (MgC12·6H2O, CAS... mineral bischofite. It is prepared by dissolving magnesium oxide, hydroxide, or carbonate in...

  1. 21 CFR 184.1431 - Magnesium oxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Magnesium oxide. 184.1431 Section 184.1431 Food... Specific Substances Affirmed as GRAS § 184.1431 Magnesium oxide. (a) Magnesium oxide (MgO, CAS Reg. No... bulky white powder (light) or a relatively dense white powder (heavy) by heating magnesium hydroxide...

  2. 21 CFR 184.1431 - Magnesium oxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Magnesium oxide. 184.1431 Section 184.1431 Food... GRAS § 184.1431 Magnesium oxide. (a) Magnesium oxide (MgO, CAS Reg. No. 1309-48-4) occurs naturally as... a relatively dense white powder (heavy) by heating magnesium hydroxide or carbonate. Heating...

  3. Magnesium deficiency: What is our status

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Low magnesium intake has been implicated in a broad range of cardiometabolic conditions, including diabetes, hypertension, and cardiovascular disease. Dietary magnesium and total body magnesium status have a widely-used but imperfect biomarker in serum magnesium. Despite serum magnesium’s limitation...

  4. Selection of a mineral binder with potentialities for the stabilization/solidification of aluminum metal

    NASA Astrophysics Data System (ADS)

    Cau Dit Coumes, C.; Lambertin, D.; Lahalle, H.; Antonucci, P.; Cannes, C.; Delpech, S.

    2014-10-01

    In a strongly alkaline medium, such as that encountered in conventional cementitious materials based on Portland cement, aluminum metal is corroded, with continued production of hydrogen. In order to develop a mineral matrix having enhanced compatibility with aluminum, a literature review was first undertaken to identify binders capable of reducing the pore solution pH compared with Portland cement. An experimental study was then carried out to measure the hydrogen production resulting from corrosion of aluminum metal rods encapsulated in the different selected cement pastes. The best results were achieved with magnesium phosphate cement, which released very little hydrogen over the duration of the study. This production could be reduced still further by adding a corrosion inhibitor (lithium nitrate) to the mixing solution. Open circuit potential measurement and Electrochemical Impedance Spectroscopy of aluminum electrode encapsulated in two pastes based on Portland cement and magnesium phosphate cement showed different redox behaviors. In the Portland cement paste, the electrochemical data confirmed the corrosion of aluminum whereas this latter tended to a passive state in the magnesium phosphate binder.

  5. [Magnesium: a kardio-renal viewpoint].

    PubMed

    Brandenburg, Vincent Matthias; Kaesler, Nadine; Kramann, Rafael; Floege, Jürgen; Marx, Nikolaus

    2016-10-01

    Disturbances in magnesium homeostasis are frequent clinical conditions, particularly the prevalence of hypomagnesaemia is high. However, it remains an open question which laboratory method is optimal to assess the magnesium level in the body. Most frequently physicians measure total magnesium in serum. Many associative data from observational studies point towards an association between low magnesium levels and increased cardiovascular risk as well as increased mortality. Vice versa, normal-to-high magnesium levels in patients with advanced renal failure translate to a better outcome. The present review summarizes our knowledge on protective effects of magnesium. Additionally, we address the limited evidence supporting targeted magnesium supplementation.

  6. Carbothermic Aluminum Production Using Scrap Aluminum As A Coolant

    DOEpatents

    LaCamera, Alfred F.

    2002-11-05

    A process for producing aluminum metal by carbothermic reduction of alumina ore. Alumina ore is heated in the presence of carbon at an elevated temperature to produce an aluminum metal body contaminated with about 10-30% by wt. aluminum carbide. Aluminum metal or aluminum alloy scrap then is added to bring the temperature to about 900-1000.degree. C. and precipitate out aluminum carbide. The precipitated aluminum carbide is filtered, decanted, or fluxed with salt to form a molten body having reduced aluminum carbide content.

  7. MTBE OXIDATION BY BIFUNCTIONAL ALUMINUM

    EPA Science Inventory

    Bifunctional aluminum, prepared by sulfating zero-valent aluminum with sulfuric acid, has a dual functionality of simultaneously decomposing both reductively- and oxidatively-degradable contaminants. In this work, the use of bifunctional aluminum for the degradation of methyl te...

  8. Formation of Lunar Mg-Spinel Lithologies by Melt-Wallrock Reaction

    NASA Astrophysics Data System (ADS)

    Ganskow, G.; Parman, S. W.; Prissel, T. C.; Jackson, C.; Dhingra, D.; Cheek, L.; Liang, Y.; Rutherford, M. J.; Hess, P.; Pieters, C. M.

    2011-12-01

    Recent remote mineralogical data acquired by the Moon Mineralogy Mapper (M3) has led to the identification of Mg-spinel-rich lithologies, likely associated with anorthosites [1,2]. This rock type has three notable petrologic characteristics: 1) a high fraction of spinel (~ 30%) 2) a low fraction of mafic minerals (less than 5% olivine or pyroxene) and 3) an unusual spinel composition (low-Fe (<5%), low-Cr and high Al). In contrast, most lunar spinels are Fe-rich ulvöspinels and chromites, which are the product of low pressure crystallization from Fe-rich lunar picritic basalts [3]. The Mg-rich spinels in the anorthosite are most similar to those found in pink spinel troctolites. The anorthosite differs from the spinel troctolite in having smaller amounts of mafic minerals and lower FeO contents in the spinel (5% versus 10% [4]). The high spinel mode, low Fe content of the spinel and lack of mafic minerals in the spinel anorthosite are not consistent with simple crystal fractionation of or crystal accumulation from basaltic lunar magma compositions [3]. However, Mg-rich spinel has been produced in experiments examining the compositions of lunar basalts which dissolved anorthosite [5]. This suggests a mechanism for forming spinel-bearing anorthosites by melt-wallrock reaction of lunar basaltic magmas with the anorthositic crust. Such reactive processes are well documented in terrestrial magmatic systems [6]. To test whether melt-wallrock reaction could have produced the spinel-anorthosite, we have conducted a set of experiments in which Apollo 15C green glass and pure anorthite glass were juxtaposed. Experiments at 1400-1450oC and 1-8 kbar produced an assemblage of anorthite, spinel (>10%) and minor mafics (<5%) in the reacted anorthite portion of the assembly. The experimental spinels are high-Mg, low-Cr and low-Fe (~10 wt%) spinels. The spinels are very similar to those found in the pink-spinel troctolites, but too high in Fe compared to the inferred composition

  9. Confession of a Magnesium Battery.

    PubMed

    Bucur, Claudiu B; Gregory, Thomas; Oliver, Allen G; Muldoon, John

    2015-09-17

    Magnesium is an ideal metal anode that has nearly double the volumetric capacity of lithium metal with a very negative reduction potential of -2.37 vs SHE. A significant advantage of magnesium is the apparent lack of dendrite formation during charging, which overcomes major safety and performance challenges encountered with using lithium metal anodes. Here, we highlight major recent advances in nonaqueous Mg electrochemistry, notably the development of electrolytes and cathodes, and discuss some of the challenges that must be overcome to realize a practical magnesium battery.

  10. Magnesium: Engineering the Surface

    NASA Astrophysics Data System (ADS)

    Chen, X. B.; Yang, H. Y.; Abbott, T. B.; Easton, M. A.; Birbilis, N.

    2012-06-01

    Magnesium (Mg) and its alloys provide numerous benefits as lightweight materials; however, industrial deployment of Mg in most instances requires anticorrosion coatings. Engineering the Mg surface is an area that has been undergoing intense research recently. Surface engineering commences with the "pretreatment" step, which can be used to modify the surface composition and morphology, resulting in surface enrichment or depletion of alloying elements. Following this, electrochemical plating (including electro- and electroless plating) and conversion coatings have emerged as common means of coating Mg. In this study, we present the key aspects relating to the science and technology associated with pretreatment, electrochemical plating, and conversion coatings. This is followed by experimental examples of engineered surfaces of industrial relevance.

  11. High energy density aluminum battery

    SciTech Connect

    Brown, Gilbert M.; Paranthaman, Mariappan Parans; Dai, Sheng; Dudney, Nancy J.; Manthiram, Arumugan; McIntyre, Timothy J.; Sun, Xiao-Guang; Liu, Hansan

    2016-10-11

    Compositions and methods of making are provided for a high energy density aluminum battery. The battery comprises an anode comprising aluminum metal. The battery further comprises a cathode comprising a material capable of intercalating aluminum or lithium ions during a discharge cycle and deintercalating the aluminum or lithium ions during a charge cycle. The battery further comprises an electrolyte capable of supporting reversible deposition and stripping of aluminum at the anode, and reversible intercalation and deintercalation of aluminum or lithium at the cathode.

  12. Constraints on formation processes of two coarse-grained calcium- aluminum-rich inclusions: a study of mantles, islands and cores

    USGS Publications Warehouse

    Meeker, G.P.

    1995-01-01

    Many coarse-grained calcium- aluminum-rich inclusions (CAIs) contain features that are inconsistent with equilibrium liquid crystallization models of origin. Spinel-free islands (SFIs) in spinel-rich cores of Type B CAIs are examples of such features. One model previously proposed for the origin of Allende 5241, a Type B1 CAI containing SFIs, involves the capture and assimilation of xenoliths by a liquid droplet in the solar nebula (El Goresy et al, 1985; MacPherson et al 1989). This study reports new textural and chemical zoning data from 5241 and identifies previously unrecognized chemical zoning patterns in the melilite mantle and in a SFI. -from Author

  13. Is the Aluminum Hypothesis Dead?

    PubMed Central

    2014-01-01

    The Aluminum Hypothesis, the idea that aluminum exposure is involved in the etiology of Alzheimer disease, dates back to a 1965 demonstration that aluminum causes neurofibrillary tangles in the brains of rabbits. Initially the focus of intensive research, the Aluminum Hypothesis has gradually been abandoned by most researchers. Yet, despite this current indifference, the Aluminum Hypothesis continues to attract the attention of a small group of scientists and aluminum continues to be viewed with concern by some of the public. This review article discusses reasons that mainstream science has largely abandoned the Aluminum Hypothesis and explores a possible reason for some in the general public continuing to view aluminum with mistrust. PMID:24806729

  14. Anodizing Aluminum with Frills.

    ERIC Educational Resources Information Center

    Doeltz, Anne E.; And Others

    1983-01-01

    "Anodizing Aluminum" (previously reported in this journal) describes a vivid/relevant laboratory experience for general chemistry students explaining the anodizing of aluminum in sulfuric acid and constrasting it to electroplating. Additions to this procedure and the experiment in which they are used are discussed. Reactions involved are…

  15. The Aluminum Smelting Process

    PubMed Central

    2014-01-01

    This introduction to the industrial primary aluminum production process presents a short description of the electrolytic reduction technology, the history of aluminum, and the importance of this metal and its production process to modern society. Aluminum's special qualities have enabled advances in technologies coupled with energy and cost savings. Aircraft capabilities have been greatly enhanced, and increases in size and capacity are made possible by advances in aluminum technology. The metal's flexibility for shaping and extruding has led to architectural advances in energy-saving building construction. The high strength-to-weight ratio has meant a substantial reduction in energy consumption for trucks and other vehicles. The aluminum industry is therefore a pivotal one for ecological sustainability and strategic for technological development. PMID:24806722

  16. In defense of magnesium sulfate.

    PubMed

    Elliott, John P; Lewis, David F; Morrison, John C; Garite, Thomas J

    2009-06-01

    Magnesium sulfate has been used by obstetricians for more than 25 years to treat preterm labor. Magnesium sulfate is effective in delaying delivery for at least 48 hours in patients with preterm labor when used in higher dosages. There do not seem to be any harmful effects of the drug on the fetus, and indeed there is a neuroprotective effect in reducing the incidence of cerebral palsy in premature newborns weighing less than 1,500 g.

  17. Thermobarometry for spinel lherzolite xenoliths in alkali basalts

    NASA Astrophysics Data System (ADS)

    Ozawa, Kazuhito; Youbi, Nasrrddine; Boumehdi, Moulay Ahmed; Nagahara, Hiroko

    2016-04-01

    Application of geothermobarometers to peridotite xenoliths has been providing very useful information on thermal and chemical structure of lithospheric or asthenospheric mantle at the time of almost instantaneous sampling by the host magmas, based on which various thermal (e.g., McKenzie et al., 2005), chemical (e.g., Griffin et al., 2003), and rheological (e.g., Ave Lallemant et al., 1980) models of lithosphere have been constructed. Geothermobarometry for garnet or plagioclase-bearing lithologies provide accurate pressure estimation, but this is not the case for the spinel peridotites, which are frequently sampled from Phanerozoic provinces in various tectonic environments (Nixon and Davies, 1987). There are several geobarometers proposed for spinel lherzolite, such as single pyroxene geothermobarometer (Mercier, 1980) and geothermobarometer based on Ca exchange between olivine and clinopyroxene (Köhler and Brey, 1990), but they have essential problems and it is usually believed that appropriated barometers do not exist for spinel lherzolites (O'Reilly et al., 1997; Medaris et al., 1999). It is thus imperative to develop reliable barometry for spinel peridotite xenoliths. We have developed barometry for spinel peridotite xenoliths by exploiting small differences in pressure dependence in relevant reactions, whose calibration was made through careful evaluation of volume changes of the reactions. This is augmented with higher levels of care in application of barometer by choosing mineral domains and their chemical components that are in equilibrium as close as possible. This is necessary because such barometry is very sensitive to changes in chemical composition induced by transient state of the system possibly owing to pressure and temperature changes as well as chemical modification, forming chemical heterogeneity or zoning frequently reported from various mantle xenoliths (Smith, 1999). Thus very carful treatment of heterogeneity, which might be trivial for

  18. Cr3+ substituted spinel ferrite nanoparticles with high coercivity

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Zuo, Xudong; Zhang, Dongmei; Wu, Chengwei; Silva, S. Ravi P.

    2016-06-01

    The low coercivity of spinel ferrites is a major barrier that significantly limits their use in high density magnetic recording applications. By controlling the substituting content of Cr3+, in this article we describe how magnetic CoCr x Fe2-x O4 (0 < x < 1.2) nanoparticles with coercivity of up to 6.4 kOe were successfully obtained by the hydrothermal process. The high coercivity is attributed to the synergetic effects of magnetocrystalline anisotropy and the nanoscale size effect. X-ray diffraction analysis confirmed the spinel structure of the nanoparticles with transmission electron microscopy (TEM) suggesting regular tetragonal morphology. The TEM indicated an edge length ranging from 15 nm to 150 nm, which increases monotonically with increasing Cr content. Raman analyses supported the proposed model on the formation mechanism of the nanoparticles, i.e. heterogeneous and homogeneous nucleation.

  19. Structure and compatibility of a magnesium electrolyte with a sulphur cathode.

    PubMed

    Kim, Hee Soo; Arthur, Timothy S; Allred, Gary D; Zajicek, Jaroslav; Newman, John G; Rodnyansky, Alexander E; Oliver, Allen G; Boggess, William C; Muldoon, John

    2011-08-09

    Magnesium metal is an ideal rechargeable battery anode material because of its high volumetric energy density, high negative reduction potential and natural abundance. Coupling Mg with high capacity, low-cost cathode materials such as electrophilic sulphur is only possible with a non-nucleophilic electrolyte. Here we show how the crystallization of the electrochemically active species formed from the reaction between hexamethyldisilazide magnesium chloride and aluminum trichloride enables the synthesis of a non-nucleophilic electrolyte. Furthermore, crystallization was essential in the identification of the electroactive species, [Mg(2)(μ-Cl)(3)·6THF](+), and vital to improvements in the voltage stability and coulombic efficiency of the electrolyte. X-ray photoelectron spectroscopy analysis of the sulphur electrode confirmed that the electrochemical conversion between sulphur and magnesium sulfide can be successfully performed using this electrolyte.

  20. Structure and compatibility of a magnesium electrolyte with a sulphur cathode

    PubMed Central

    Kim, Hee Soo; Arthur, Timothy S.; Allred, Gary D.; Zajicek, Jaroslav; Newman, John G.; Rodnyansky, Alexander E.; Oliver, Allen G.; Boggess, William C.; Muldoon, John

    2011-01-01

    Magnesium metal is an ideal rechargeable battery anode material because of its high volumetric energy density, high negative reduction potential and natural abundance. Coupling Mg with high capacity, low-cost cathode materials such as electrophilic sulphur is only possible with a non-nucleophilic electrolyte. Here we show how the crystallization of the electrochemically active species formed from the reaction between hexamethyldisilazide magnesium chloride and aluminum trichloride enables the synthesis of a non-nucleophilic electrolyte. Furthermore, crystallization was essential in the identification of the electroactive species, [Mg2(μ-Cl)3·6THF]+, and vital to improvements in the voltage stability and coulombic efficiency of the electrolyte. X-ray photoelectron spectroscopy analysis of the sulphur electrode confirmed that the electrochemical conversion between sulphur and magnesium sulfide can be successfully performed using this electrolyte. PMID:21829189

  1. Cement from magnesium substituted hydroxyapatite.

    PubMed

    Lilley, K J; Gbureck, U; Knowles, J C; Farrar, D F; Barralet, J E

    2005-05-01

    Brushite cement may be used as a bone graft material and is more soluble than apatite in physiological conditions. Consequently it is considerably more resorbable in vivo than apatite forming cements. Brushite cement formation has previously been reported by our group following the mixture of nanocrystalline hydroxyapatite and phosphoric acid. In this study, brushite cement was formed from the reaction of nanocrystalline magnesium-substituted hydroxyapatite with phosphoric acid in an attempt to produce a magnesium substituted brushite cement. The presence of magnesium was shown to have a strong effect on cement composition and strength. Additionally the presence of magnesium in brushite cement was found to reduce the extent of brushite hydrolysis resulting in the formation of HA. By incorporating magnesium ions in the apatite reactant structure the concentration of magnesium ions in the liquid phase of the cement was controlled by the dissolution rate of the apatite. This approach may be used to supply other ions to cement systems during setting as a means to manipulate the clinical performance and characteristics of brushite cements.

  2. A fundamental study on the structural integrity of magnesium alloys joined by friction stir welding

    NASA Astrophysics Data System (ADS)

    Rao, Harish Mangebettu

    The goal of this research is to study the factors that influence the physical and mechanical properties of lap-shear joints produced using friction stir welding. This study focuses on understanding the effect of tool geometry and weld process parameters including the tool rotation rate, tool plunge depth and dwell time on the mechanical performance of similar magnesium alloy and dissimilar magnesium to aluminum alloy weld joints. A variety of experimental activities were conducted including tensile and fatigue testing, fracture surface and failure analysis, microstructure characterization, hardness measurements and chemical composition analysis. An investigation on the effect of weld process conditions in friction stir spot welding of magnesium to magnesium produced in a manner that had a large effective sheet thickness and smaller interfacial hook height exhibited superior weld strength. Furthermore, in fatigue testing of friction stir spot welded of magnesium to magnesium alloy, lap-shear welds produced using a triangular tool pin profile exhibited better fatigue life properties compared to lap-shear welds produced using a cylindrical tool pin profile. In friction stir spot welding of dissimilar magnesium to aluminum, formation of intermetallic compounds in the stir zone of the weld had a dominant effect on the weld strength. Lap-shear dissimilar welds with good material mixture and discontinues intermetallic compounds in the stir zone exhibited superior weld strength compared to lap-shear dissimilar welds with continuous formation of intermetallic compounds in the stir zone. The weld structural geometry like the interfacial hook, hook orientation and bond width also played a major role in influencing the weld strength of the dissimilar lap-shear friction stir spot welds. A wide scatter in fatigue test results was observed in friction stir linear welds of aluminum to magnesium alloys. Different modes of failure were observed under fatigue loading including crack

  3. Structure and Electrical Properties of Mn-Cu-O Spinels

    NASA Astrophysics Data System (ADS)

    Bobruk, M.; Durczak, K.; Dąbek, J.; Brylewski, T.

    2017-03-01

    The study presents the results of structural and electrical conductivity investigations of a Cu1.3Mn1.7O4 spinel obtained using EDTA gel processes. An amorphous gel was synthesized and calcinated for 5 h in air at temperatures of 673, 773, 873, and 973 K. When calcinating the gel at temperatures below 973 K, the obtained powders consisted of two phases—the regular Cu1.5Mn1.5O4 spinel and manganese(III) oxide. At 973 K, Mn2O3 was no longer observed, but a new Mn3O4 phase appeared in addition to the Cu1.5Mn1.5O4 spinel. Green bodies prepared from these powders were sintered for 2 h in air at 1393 K. The obtained sinters had a porosity of around 12% and were composed predominantly of the spinel phase, with minor amounts of Mn3O4 and, in the case of three of four sinters—CuO. Electrical conductivity measurements were taken over the temperature range of 300-1073 K. A change in the character of conductivity of the studied sinters was observed in the range of 400-430 K, and it was associated with an increase in activation energy from 0.20 to 0.56 eV. The electrical conductivity of the studied sinters ranged from 74.8 to 88.4 S cm-1, which makes the Cu1.3Mn1.7O4 material suitable for application as a protective-conducting coating in IT-SOFC ferritic stainless steel interconnects.

  4. Magnesium and Dialysis: The Neglected Cation.

    PubMed

    Alhosaini, Mohamad; Leehey, David J

    2015-09-01

    Disorders of magnesium homeostasis are very common in dialysis patients but have received scant attention. In this review, we address measurement of plasma magnesium, magnesium balance and the factors that affect magnesium flux during dialysis, the prevalence of hypo- and hypermagnesemia in dialysis patients, and the potential clinical significance of hypo- and hypermagnesemia in dialysis patients. Many factors can affect plasma magnesium concentration, including diet, nutritional status (including plasma albumin level), medications (such as proton pump inhibitors), and dialysis prescription. Further interventional studies to determine the effect of normalization of plasma magnesium concentration on clinical outcomes are needed. At the present time, we recommend that predialysis plasma magnesium be measured on a regular basis, with the dialysate magnesium concentration adjusted to maintain plasma magnesium concentration within the normal range.

  5. Atomic layer deposition of nickel-cobalt spinel thin films.

    PubMed

    Hagen, D J; Tripathi, T S; Karppinen, M

    2017-04-05

    We report the atomic layer deposition (ALD) of high-quality crystalline thin films of the spinel-oxide system (Co1-xNix)3O4. These spinel oxides are ferrimagnetic p-type semiconductors, and promising material candidates for several applications ranging from photovoltaics and spintronics to thermoelectrics. The spinel phase is obtained for Ni contents exceeding the x = 0.33 limit for bulk samples. It is observed that the electrical resistivity decreases continuously with x while the magnetic moment increases up to x = 0.5. This is in contrast to bulk samples where a decrease of resistivity is not observed for x > 0.33 due to the formation of a rock-salt phase. From UV-VIS-NIR absorption measurements, a change from distinct absorption edges for the parent oxide Co3O4 to a continuous absorption band ranging deep into the near infrared for 0 < x ≤ 0.5 was observed. The conformal deposition of dense films on high-aspect-ratio patterns is demonstrated.

  6. Determination of ferrous and total iron in refractory spinels

    SciTech Connect

    Amonette, James E.; Matyas, Josef

    2015-12-30

    Accurate and precise determination of the redox state of iron (Fe) in spinels presents a significant challenge due to their refractory nature. The resultant extreme conditions needed to obtain complete dissolution generally oxidize some of the Fe(II) initially present and thus prevent the use of colorimetric methods for Fe(II) measurements. To overcome this challenge we developed a hybrid oxidimetric/colorimetric approach, using Ag(I) as the oxidimetric reagent for determination of Fe(II) and 1,10-phenanthroline as the colorimetric reagent for determination of total Fe. This approach, which allows determination of Fe(II) and total Fe on the same sample, was tested on a series of four geochemical reference materials and then applied to the analysis of Fe(Ni) spinel crystals isolated from simulated high-level-waste (HLW) glass and of several reagent magnetites. Results for the reference materials were in excellent agreement with published values, with the exception of USGS BIR-1, for which higher Fe(II) values and lower total Fe values were obtained. The Fe(Ni) spinels showed Fe(II) values at the detection limit (ca. 0.05 wt% Fe) and total Fe values slightly higher than obtained by total elemental analysis. For the magnetite samples, total Fe values were in agreement with reference results, but a wide range in Fe(II) values was obtained indicating various degrees of conversion to maghemite.

  7. Formation of spinel-, hibonite-rich inclusions found in CM2 carbonaceous chrondrites

    SciTech Connect

    Simon, S B; Grossman, L; Hutcheon, I D; Phinney, D L; Weber, P K; Fallon, S J

    2005-11-03

    We report petrography, mineral chemistry, bulk chemistry, and bulk isotopic compositions of a suite of 40 spinel-rich inclusions from the Murchison (CM2) carbonaceous chondrite. Seven types of inclusions are identified based on mineralogy: spinel-hibonite-perovskite; spinel-perovskite-pyroxene; spinel-perovskite-melilite; spinel-hibonite-perovskite-melilite; spinel-hibonite; spinel-pyroxene; and spinel-melilite-anorthite. Hibonite-bearing inclusions have Ti-poor spinel compared to the hibonite-free ones, and spinel-hibonite-perovskite inclusions have the highest average bulk TiO{sub 2} contents (7.8 wt%). The bulk CaO/Al{sub 2}O{sub 3} ratios of the inclusions range from 0.005-0.21, well below the solar value of 0.79. Hibonite-, spinel-rich inclusions consist of phases that are not predicted by condensation calculations to coexist; in the equilibrium sequence, hibonite is followed by melilite, which is followed by spinel. Therefore, hibonite-melilite or melilite-spinel inclusions should be dominant instead. One explanation for the 'missing melilite' is that it condensed as expected but was lost due to evaporation of Mg and Ca during heating and melting of spherule precursors. If this theory were correct, melilite-poor spherules would have isotopically heavy Mg and Ca. Except for one inclusion with F{sub Mg} = 4.3 {+-} 2.6{per_thousand}/amu and another with isotopically light Ca (F{sub Ca} = 3.4 {+-} 2.0{per_thousand}/amu), however, all the inclusions we analyzed have normal isotopic compositions within their 2{sigma} uncertainties. Thus, we found no evidence for significant mass-dependent fractionation. Our preferred explanation for the general lack of melilite among hibonite-, spinel-bearing inclusions is kinetic inhibition of melilite condensation relative to spinel. Because of similarities between the crystal structures of hibonite and spinel, it should be easier for spinel to form from hibonite than for melilite to do so.

  8. A successful management of aluminum phosphide intoxication

    PubMed Central

    Moazezi, Zoleika; Abedi, Seyed Hassan

    2011-01-01

    Background: Aluminum Phosphide or rice tablet is one of the most common pesticides which leads to accidental or intentional acute intoxication and finally death. In this paper, we describe a successful management of intoxication with rice tablet in a young girl. Case Presentation: A 14-year-old girl was admitted due to consumption of rice tablet. Gastric washing with two vials of sodium bicarbonate and discharge suction was done. In the first 24 hours, the patient underwent recurrent hydration, dopamine infusion with sodium bicarbonate, calcium, magnesium and amiodarone. On the second day of admission, the patient was transferred to intensive care unit (ICU) and five days later, she was discharged without liver or renal complications. Conclusion: Short interval between consumption of this tablet and start of the treatment and on time rescue to the patient can be some of the important factors to prevent early death in intoxication with this tablet. PMID:24049589

  9. Clinical biochemistry of aluminum

    SciTech Connect

    King, S.W.; Savory, J.; Wills, M.R.

    1981-05-01

    Aluminum toxicity has been implicated in the pathogenesis of a number of clinical disorders in patients with chronic renal failure on long-term intermittent hemodialysis treatment. The predominant disorders have been those involving either bone (osteomalacic dialysis osteodystrophy) or brain (dialysis encephalopathy). In nonuremic patients, an increased brain aluminum concentration has been implicated as a neurotoxic agent in the pathogenesis of Alzheimer's disease and was associated with experimental neurofibrillary degeneration in animals. The brain aluminum concentrations of patients dying with the syndrome of dialysis encephalopathy (dialysis dementia) are significantly higher than in dialyzed patients without the syndrome and in nondialyzed patients. Two potential sources for the increased tissue content of aluminum in patients on hemodialysis have been proposed: (1) intestinal absorption from aluminum containing phosphate-binding gels, and (2) transfer across the dialysis membrane from aluminum in the water used to prepare the dialysate. These findings, coupled with our everyday exposure to the ubiquitous occurrence of aluminum in nature, have created concerns over the potential toxicity of this metal.

  10. Elasticity of some mantle crystal structures. I - Pleonaste and hercynite spinel.

    NASA Technical Reports Server (NTRS)

    Wang, H.; Simmons, G.

    1972-01-01

    The elasticity of high-pressure mantle phases can be characterized by using data for chemically similar crystal compounds. The single-crystal elastic constants are determined as a function of pressure and temperature for pleonaste spinel and at room conditions for hercynite spinel. The bulk modulus increases from 1.95 Mb for pleonaste spinel to 2.10 Mb for hercynite spinel. Low or negative values of the pressure derivatives of shear constants are characteristic of the spinel structure and imply a low kinetic barrier to phase transformations and diffusion. Compressional and shear velocities of the spinel phase of olivine are estimated as a function of mean atomic weight by using the pleonaste and hercynite data.

  11. Cast Aluminum Bonding Study

    DTIC Science & Technology

    1988-05-01

    fabricated using P?-’r;est11 bur)ld II19 te(hnll I Oly with 6 cIsL nqs. The cast a lumi num alloy used was A357 . The sur- face preparation was phosphoric acid...from a cast aluminum alloy designated A357 . The bonding surfaces of the adherends were prepared using PAA. One primer and two adhesives considered...System, Cast Aluminum Lap Shear 18 11 Bond Area of 350°F Adhesive System, Cast Aluminum Lap Shear 19 vi LIST OF TABLES TABLE PAGE 1 A357 Chemical

  12. Purifying Aluminum by Vacuum Distillation

    NASA Technical Reports Server (NTRS)

    Du Fresne, E. R.

    1985-01-01

    Proposed method for purifying aluminum employs one-step vacuum distillation. Raw material for process impure aluminum produced in electrolysis of aluminum ore. Impure metal melted in vacuum. Since aluminum has much higher vapor pressure than other constituents, boils off and condenses on nearby cold surfaces in proportions much greater than those of other constituents.

  13. Magnesium and healthy aging.

    PubMed

    Veronese, Nicola; Zanforlini, Bruno Micael; Manzato, Enzo; Sergi, Giuseppe

    2015-01-01

    Magnesium (Mg) is relatively stable in the intracellular compartment, although decreases linearly with advancing age. This begs the question as to whether Mg could be used as biomarker of aging. A biomarker of aging is a biological parameter of an organism that, in the absence of disease, better predicts functional capability at a later age than the chronological age. Bone and muscle Mg content might be useful biomarkers, but the need for biopsies and the heterogeneous distribution of Mg in bones and muscles strongly limit the application of these methods in clinical practice. Similar considerations can be made for urinary Mg assessment, particularly after a loading test. Markers of Mg in blood seem fairly unreliable as biomarkers of aging since they are strongly dependent upon renal function, do not reflect the intracellular Mg status, and, in some investigations, are within normal ranges although other Mg parameters are not. Other investigations (e.g. nuclear magnetic resonance with fluorescent probes) seem to be promising, but their availability remains limited.

  14. Magnetoreflection of light in CoFe2O4 magnetostrictive spinel

    NASA Astrophysics Data System (ADS)

    Sukhorukov, Yu. P.; Telegin, A. V.; Nosov, A. P.; Bessonov, V. D.; Buchkevich, A. A.

    2016-09-01

    The reflection and magnetoreflection of natural light within the infrared spectral range is studied in single crystals of CoFe2O4 ferrimagnetic ferrite spinel. Correlation between the reflection of light and magnetoelastic characteristics of this spinel is found. It is shown that the most significant magnetic-field-induced changes in the magnetoreflection of the spinel occur near the fundamental absorption edge and within the range of the phonon spectrum.

  15. History of development of polycrystalline optical spinel in the U.S.

    NASA Astrophysics Data System (ADS)

    Harris, Daniel C.

    2005-05-01

    Optical quality polycrystalline spinel (MgAl2O4) has been sought as a visible- and infrared-transmitting material since the 1960s because of its potential for transparent armor and durable sensor windows. Its physical properties were known from synthetic crystals available since ~1950 from Linde Air Products. In the late 1960s, methods to process powder into transparent, polycrystalline spinel were investigated at North Carolina State University, General Electric Co., AVCO, and Westinghouse, mainly with Government support. The leading figure in the development of polycrystalline spinel was Don Roy, who began work on spinel at Coors Ceramics around 1970, initially for transparent armor. In the late 1970s, both Coors Ceramics and Raytheon Research Division were funded to make spinel for the infrared dome of the Advanced Short-Range Air-to-Air Missile, an application that disappeared by 1980. In the late 1980s, there was another burst of activity when spinel was a candidate for the Stinger Missile. By 1990, Raytheon had dropped spinel and the material was spun off by Coors Ceramics to Alpha Optical Systems, whose technical effort was led by Don Roy. With low commercial sales potential for spinel, Alpha was dissolved in 1993. RCS Technologies took over a Government contract seeking 200-mm spinel domes for the Harrier aircraft, but this effort ended in 1996 and RCS was dissolved. In 1998, the Army enlisted TA&T to make spinel for transparent armor. Other potential applications appeared and TA&T received numerous Government development contracts. Demand for the still-unavailable spinel drew Surmet to begin development in 2002. In early 2005, spinel is under active development at TA&T and Surmet.

  16. A new lithium-rich anti-spinel in Li-O-Br system.

    PubMed

    Zhang, J; Zhu, J; Wang, L; Zhao, Y

    2015-06-14

    In spinel-type materials currently known, the divalent anions are arranged in a closed-pack lattice and cations of various valences occupy some or all of the tetrahedral and octahedral sites. We report here the first discovery of an "electronically inverted" anti-spinel. The new material, crystallized in a defect spinel structure, was obtained from the dehydration of Li5Br(OH)4 under moderate pressure and temperature conditions.

  17. Thermodynamic properties of spinel MgAl2O4: A mass spectrometric study

    NASA Astrophysics Data System (ADS)

    Shornikov, S. I.

    2017-02-01

    The activities of oxides in stoichiometric spinel MgAl2O4 in the temperature range 1851-2298 K were determined from the data obtained by the Knudsen effusion mass spectrometry. The resulting Gibbs energies of spinel formation from simple oxides, the enthalpies and entropies of spinel formation from simple oxides (-12.02 ± 1.14 kJ/mol and 5.03 ± 0.56 J/(mol K), respectively), and the spinel melting enthalpy (55.81 ± 4.62 kJ/mol) satisfactorily agree with the available thermodynamic data.

  18. Corrosion Inhibitors for Aluminum.

    ERIC Educational Resources Information Center

    Muller, Bodo

    1995-01-01

    Describes a simple and reliable test method used to investigate the corrosion-inhibiting effects of various chelating agents on aluminum pigments in aqueous alkaline media. The experiments that are presented require no complicated or expensive electronic equipment. (DDR)

  19. Walnut Hulls Clean Aluminum

    NASA Technical Reports Server (NTRS)

    Colberg, W. R.; Gordon, G. H.; Jackson, C. H.

    1984-01-01

    Hulls inflict minimal substrate damage. Walnut hulls found to be best abrasive for cleaning aluminum surfaces prior to painting. Samples blasted with walnut hulls showed no compressive stress of surface.

  20. Aluminum powder applications

    SciTech Connect

    Gurganus, T.B.

    1995-08-01

    Aluminum powders have physical and metallurgical characteristics related to their method of manufacture that make them extremely important in a variety of applications. They can propel rockets, improve personal hygiene, increase computer reliability, refine exotic alloys, and reduce weight in the family sedan or the newest Air Force fighter. Powders formed into parts for structural and non-structural applications hold the key to some of the most exciting new developments in the aluminum future.

  1. CORROSION PROTECTION OF ALUMINUM

    DOEpatents

    Dalrymple, R.S.; Nelson, W.B.

    1963-07-01

    Treatment of aluminum-base metal surfaces in an autoclave with an aqueous chromic acid solution of 0.5 to 3% by weight and of pH below 2 for 20 to 50 hrs at 160 to 180 deg C produces an extremely corrosion-resistant aluminum oxidechromium film on the surface. A chromic acid concentration of 1 to 2% and a pH of about 1 are preferred. (D.C.W.)

  2. Corrosion Protection of Aluminum

    DOEpatents

    Dalrymple, R. S.; Nelson, W. B.

    1963-07-01

    Treatment of aluminum-base metal surfaces in an autoclave with an aqueous chromic acid solution of 0.5 to 3% by weight and of pH below 2 for 20 to 50 hrs at 160 to 180 deg C produces an extremely corrosion-resistant aluminum oxidechromium film on the surface. A chromic acid concentration of 1 to 2% and a pH of about 1 are preferred.

  3. The tensile strength of 339 aluminum reinforced with Kaowool fibers: A comparison of T5 and T6 heat treatments

    SciTech Connect

    Baxter, W.J.; Sachdev, A.K.

    1999-07-01

    This study compares the effects of T5 and T6 heat treatment on the tensile strengths of both KAOWOOL fiber reinforced and unreinforced 339 aluminum. The 339 Al-T6 is stronger than 339 AL-T5 (as expected), but for a KAOWOOL/339 Al composite, the T5 condition is substantially stronger than the T6. The controlling parameter is the strength of the aluminum dendrites, which in turn is proportional to the concentration of magnesium retained in the dendrites. In the T5 condition, more than half of the magnesium is in the form of large intermetallics in both the unreinforced alloy and the KAOWOOL/339 Al composite. During a T6 heat treatment, magnesium in the intermetallics is redissolved. In the unreinforced T6 alloy, this additional magnesium is retained in and strengthens the dendrites. But in the T6 composite, the magnesium segregates extensively to the KAOWOOL/aluminum interfaces depleting and softening the dendrites. This factor along is sufficient to account for the low strength of the T6 composites. The tensile strengths of both the T5 and T6 composites correspond to the calculated values for a perfectly bonded system.

  4. System and process for production of magnesium metal and magnesium hydride from magnesium-containing salts and brines

    DOEpatents

    McGrail, Peter B.; Nune, Satish K.; Motkuri, Radha K.; Glezakou, Vassiliki-Alexandra; Koech, Phillip K.; Adint, Tyler T.; Fifield, Leonard S.; Fernandez, Carlos A.; Liu, Jian

    2016-11-22

    A system and process are disclosed for production of consolidated magnesium metal products and alloys with selected densities from magnesium-containing salts and feedstocks. The system and process employ a dialkyl magnesium compound that decomposes to produce the Mg metal product. Energy requirements and production costs are lower than for conventional processing.

  5. [Development of biodegradable magnesium-based biomaterials].

    PubMed

    Zhu, Shengfa; Xu, Li; Huang, Nan

    2009-04-01

    Magnesium is a macroelement which is indispensable to human bodies. As a lightweight metal with high specific strength and favorable biocompatibility, magnesium and its alloys have been introduced in the field of biomedical materials research and have a broad application prospect. It is possible to develop new type of biodegradable medical magnesium alloys by use of the poor corrosion resistance of magnesium. Bioabsorbable magnesium stents implanted in vivo could mechanically support the vessel in a short term, effectly prevent the acute coronary occlusion and in-stent restenosis, and then be gradully biodegraded and completely absorbed in a long term. Osteoconductive bioactivity in magnesium-based alloys could promote the apposition growth of bone tissue. This paper reviews the progress of magnesium and its alloys applied in bone tissue and cardiovascular stents, and the prospect of the future research of magnesium-based biomaterials is discussed.

  6. Magnesium/Calcium Competition at Excitable Membranes.

    ERIC Educational Resources Information Center

    Belzer, Bill; Fry, Panni

    1998-01-01

    Considers some consequences of altering intracellular calcium supply by magnesium concentration changes. Focuses on using this procedure as an exercise with allied health students as they witness therapeutic uses of magnesium and other calcium entry inhibitors. (DDR)

  7. Magnesium silicide intermetallic alloys

    NASA Astrophysics Data System (ADS)

    Li, Gh.; Gill, H. S.; Varin, R. A.

    1993-11-01

    Methods of induction melting an ultra-low-density magnesium silicide (Mg2Si) intermetallic and its alloys and the resulting microstructure and microhardness were studied. The highest quality ingots of Mg2Si alloys were obtained by triple melting in a graphite crucible coated with boron nitride to eliminate reactivity, under overpressure of high-purity argon (1.3 X 105 Pa), at a temperature close to but not exceeding 1105 °C ± 5 °C to avoid excessive evaporation of Mg. After establishing the proper induction-melting conditions, the Mg-Si binary alloys and several Mg2Si alloys macroalloyed with 1 at. pct of Al, Ni, Co, Cu, Ag, Zn, Mn, Cr, and Fe were induction melted and, after solidification, investigated by optical microscopy and quantitative X-ray energy dispersive spectroscopy (EDS). Both the Mg-rich and Si-rich eutectic in the binary alloys exhibited a small but systematic increase in the Si content as the overall composition of the binary alloy moved closer toward the Mg2Si line compound. The Vickers microhardness (VHN) of the as-solidified Mg-rich and Si-rich eutectics in the Mg-Si binary alloys decreased with increasing Mg (decreasing Si) content in the eutectic. This behavior persisted even after annealing for 75 hours at 0.89 pct of the respective eutectic temperature. The Mg-rich eutectic in the Mg2Si + Al, Ni, Co, Cu, Ag, and Zn alloys contained sections exhibiting a different optical contrast and chemical composition than the rest of the eutectic. Some particles dispersed in the Mg2Si matrix were found in the Mg2Si + Cr, Mn, and Fe alloys. The EDS results are presented and discussed and compared with the VHN data.

  8. Solid-state rechargeable magnesium battery

    DOEpatents

    Shao, Yuyan; Liu, Jun; Liu, Tianbiao; Li, Guosheng

    2016-09-06

    Embodiments of a solid-state electrolyte comprising magnesium borohydride, polyethylene oxide, and optionally a Group IIA or transition metal oxide are disclosed. The solid-state electrolyte may be a thin film comprising a dispersion of magnesium borohydride and magnesium oxide nanoparticles in polyethylene oxide. Rechargeable magnesium batteries including the disclosed solid-state electrolyte may have a coulombic efficiency .gtoreq.95% and exhibit cycling stability for at least 50 cycles.

  9. 21 CFR 184.1440 - Magnesium stearate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Magnesium stearate. 184.1440 Section 184.1440 Food... Specific Substances Affirmed as GRAS § 184.1440 Magnesium stearate. (a) Magnesium stearate (Mg(C17H34COO)2, CAS Reg. No. 557-04-0) is the magnesium salt of stearic acid. It is produced as a white precipitate...

  10. 21 CFR 184.1440 - Magnesium stearate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Magnesium stearate. 184.1440 Section 184.1440 Food... GRAS § 184.1440 Magnesium stearate. (a) Magnesium stearate (Mg(C17H34COO)2, CAS Reg. No. 557-04-0) is the magnesium salt of stearic acid. It is produced as a white precipitate by the addition of...

  11. 21 CFR 184.1425 - Magnesium carbonate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium carbonate. 184.1425 Section 184.1425 Food... Specific Substances Affirmed as GRAS § 184.1425 Magnesium carbonate. (a) Magnesium carbonate (molecular formula approximately (MgCO3)4·Mg(OH)2·5H2O, CAS Reg. No. 39409-82-0) is also known as magnesium...

  12. 21 CFR 184.1443 - Magnesium sulfate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Magnesium sulfate. 184.1443 Section 184.1443 Food... GRAS § 184.1443 Magnesium sulfate. (a) Magnesium sulfate (MgSO4·7H2O, CAS Reg. No. 10034-99-8) occurs naturally as the mineral epsomite. It is prepared by neutralization of magnesium oxide, hydroxide,...

  13. 21 CFR 184.1440 - Magnesium stearate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Magnesium stearate. 184.1440 Section 184.1440 Food... Specific Substances Affirmed as GRAS § 184.1440 Magnesium stearate. (a) Magnesium stearate (Mg(C17H34COO)2, CAS Reg. No. 557-04-0) is the magnesium salt of stearic acid. It is produced as a white precipitate...

  14. 21 CFR 184.1440 - Magnesium stearate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Magnesium stearate. 184.1440 Section 184.1440 Food... Specific Substances Affirmed as GRAS § 184.1440 Magnesium stearate. (a) Magnesium stearate (Mg(C17H34COO)2, CAS Reg. No. 557-04-0) is the magnesium salt of stearic acid. It is produced as a white precipitate...

  15. 21 CFR 184.1425 - Magnesium carbonate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Magnesium carbonate. 184.1425 Section 184.1425... GRAS § 184.1425 Magnesium carbonate. (a) Magnesium carbonate (molecular formula approximately (MgCO3)4·Mg(OH)2·5H2O, CAS Reg. No. 39409-82-0) is also known as magnesium carbonate hydroxide. It is a...

  16. 21 CFR 184.1440 - Magnesium stearate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium stearate. 184.1440 Section 184.1440 Food... Specific Substances Affirmed as GRAS § 184.1440 Magnesium stearate. (a) Magnesium stearate (Mg(C17H34COO)2, CAS Reg. No. 557-04-0) is the magnesium salt of stearic acid. It is produced as a white precipitate...

  17. 21 CFR 184.1426 - Magnesium chloride.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Magnesium chloride. 184.1426 Section 184.1426 Food... GRAS § 184.1426 Magnesium chloride. (a) Magnesium chloride (MgC12·6H2O, CAS Reg. No. 7786-30-3) is a... prepared by dissolving magnesium oxide, hydroxide, or carbonate in aqueous hydrochloric acid solution...

  18. Shock Behavior of 2139-T8 Aluminum

    NASA Astrophysics Data System (ADS)

    Casem, Daniel; Dandekar, Dattatraya

    2009-06-01

    Plane shock wave experiments have been conducted on an aluminum alloy, Al 2139-T8, to determine its response under high rates of loading. The alloying elements, copper, magnesium, and silver, have been found to improve the fatigue life and fracture toughness of Al 2139 and mitigate impact induced damage. The present suite of experiments provide measurements of the Hugoniot Elastic Limit (HEL), compression, shear strength, and spall threshold to 5 GPa. Longitudinal measurements are made with a VISAR system and shear strength is determined through direct measurements of lateral stress with manganin gages. Preliminary results indicate an HEL of approximately 0.9 GPa, a value consistent with yield stress measured at rates as high as 40k/s, and a constant spall pull-back velocity of approximately 180 m/s. The results also show that it continues to retain shear strength like other aluminum alloys. The EPIC code (Elastic Plastic Impact Calculations) is used to simulate the experimental results.

  19. Cotectic proportions of olivine and spinel in olivine-tholeiitic basalt and evaluation of pre-eruptive processes

    USGS Publications Warehouse

    Roeder, Peter; Gofton, Emma; Thornber, Carl

    2006-01-01

    The volume %, distribution, texture and composition of coexisting olivine, Cr-spinel and glass has been determined in quenched lava samples from Hawaii, Iceland and mid-oceanic ridges. The volume ratio of olivine to spinel varies from 60 to 2800 and samples with >0·02% spinel have a volume ratio of olivine to spinel of approximately 100. A plot of wt % MgO vs ppm Cr for natural and experimental basaltic glasses suggests that the general trend of the glasses can be explained by the crystallization of a cotectic ratio of olivine to spinel of about 100. One group of samples has an olivine to spinel ratio of approximately 100, with skeletal olivine phenocrysts and small (<50 μm) spinel crystals that tend to be spatially associated with the olivine phenocrysts. The large number of spinel crystals included within olivine phenocrysts is thought to be due to skeletal olivine phenocrysts coming into physical contact with spinel by synneusis during the chaotic conditions of ascent and extrusion. A second group of samples tend to have large olivine phenocrysts relatively free of included spinel, a few large (>100 μm) spinel crystals that show evidence of two stages of growth, and a volume ratio of olivine to spinel of 100 to well over 1000. The olivine and spinel in this group have crystallized more slowly with little physical interaction, and show evidence that they have accumulated in a magma chamber.

  20. 76 FR 69284 - Pure Magnesium From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-08

    ... COMMISSION Pure Magnesium From China Determination On the basis of the record \\1\\ developed in the subject... order on pure magnesium from China would be likely to lead to continuation or recurrence of material... USITC Publication 4274 (October 2011), entitled Pure Magnesium from China: Investigation No....

  1. Synthesis of superconducting magnesium diboride objects

    DOEpatents

    Finnemore, Douglas K.; Canfield, Paul C.; Bud'ko, Sergey L.; Ostenson, Jerome E.; Petrovic, Cedomir; Cunningham, Charles E.; Lapertot, Gerard

    2003-08-15

    A process to produce magnesium diboride objects from boron objects with a similar form is presented. Boron objects are reacted with magnesium vapor at a predetermined time and temperature to form magnesium diboride objects having a morphology similar to the boron object's original morphology.

  2. 21 CFR 582.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium hydroxide. 582.1428 Section 582.1428 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1428 Magnesium hydroxide. (a) Product. Magnesium hydroxide. (b) Conditions of use....

  3. 21 CFR 182.2437 - Magnesium silicate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Magnesium silicate. 182.2437 Section 182.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations,...

  4. 21 CFR 582.1431 - Magnesium oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium oxide. 582.1431 Section 582.1431 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1431 Magnesium oxide. (a) Product. Magnesium oxide. (b) Conditions of use. This substance...

  5. 21 CFR 182.2437 - Magnesium silicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium silicate. 182.2437 Section 182.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations,...

  6. 21 CFR 184.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Magnesium hydroxide. 184.1428 Section 184.1428... Listing of Specific Substances Affirmed as GRAS § 184.1428 Magnesium hydroxide. (a) Magnesium hydroxide... is prepared as a white precipitate by the addition of sodium hydroxide to a water soluble...

  7. 21 CFR 582.1431 - Magnesium oxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Magnesium oxide. 582.1431 Section 582.1431 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1431 Magnesium oxide. (a) Product. Magnesium oxide. (b) Conditions of use. This substance...

  8. 21 CFR 201.71 - Magnesium labeling.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 4 2011-04-01 2011-04-01 false Magnesium labeling. 201.71 Section 201.71 Food and... LABELING Labeling Requirements for Over-the-Counter Drugs § 201.71 Magnesium labeling. (a) The labeling of over-the-counter (OTC) drug products intended for oral ingestion shall contain the magnesium...

  9. 21 CFR 184.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Magnesium hydroxide. 184.1428 Section 184.1428... Listing of Specific Substances Affirmed as GRAS § 184.1428 Magnesium hydroxide. (a) Magnesium hydroxide... is prepared as a white precipitate by the addition of sodium hydroxide to a water soluble...

  10. 21 CFR 201.71 - Magnesium labeling.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 4 2013-04-01 2013-04-01 false Magnesium labeling. 201.71 Section 201.71 Food and... LABELING Labeling Requirements for Over-the-Counter Drugs § 201.71 Magnesium labeling. (a) The labeling of over-the-counter (OTC) drug products intended for oral ingestion shall contain the magnesium...

  11. 21 CFR 582.1425 - Magnesium carbonate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium carbonate. 582.1425 Section 582.1425 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1425 Magnesium carbonate. (a) Product. Magnesium carbonate. (b) Conditions of use....

  12. 21 CFR 582.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Magnesium hydroxide. 582.1428 Section 582.1428 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1428 Magnesium hydroxide. (a) Product. Magnesium hydroxide. (b) Conditions of use....

  13. 21 CFR 582.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Magnesium hydroxide. 582.1428 Section 582.1428 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1428 Magnesium hydroxide. (a) Product. Magnesium hydroxide. (b) Conditions of use....

  14. 21 CFR 582.2437 - Magnesium silicate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Magnesium silicate. 582.2437 Section 582.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations,...

  15. 21 CFR 582.1431 - Magnesium oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Magnesium oxide. 582.1431 Section 582.1431 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1431 Magnesium oxide. (a) Product. Magnesium oxide. (b) Conditions of use. This substance...

  16. 21 CFR 582.2437 - Magnesium silicate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Magnesium silicate. 582.2437 Section 582.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations,...

  17. 21 CFR 582.2437 - Magnesium silicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Magnesium silicate. 582.2437 Section 582.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations,...

  18. 21 CFR 182.2437 - Magnesium silicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Magnesium silicate. 182.2437 Section 182.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations,...

  19. 21 CFR 582.1425 - Magnesium carbonate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Magnesium carbonate. 582.1425 Section 582.1425 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1425 Magnesium carbonate. (a) Product. Magnesium carbonate. (b) Conditions of use....

  20. 21 CFR 182.2437 - Magnesium silicate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Magnesium silicate. 182.2437 Section 182.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations,...

  1. 21 CFR 201.71 - Magnesium labeling.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 4 2012-04-01 2012-04-01 false Magnesium labeling. 201.71 Section 201.71 Food and... LABELING Labeling Requirements for Over-the-Counter Drugs § 201.71 Magnesium labeling. (a) The labeling of over-the-counter (OTC) drug products intended for oral ingestion shall contain the magnesium...

  2. 21 CFR 201.71 - Magnesium labeling.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 4 2014-04-01 2014-04-01 false Magnesium labeling. 201.71 Section 201.71 Food and... LABELING Labeling Requirements for Over-the-Counter Drugs § 201.71 Magnesium labeling. (a) The labeling of over-the-counter (OTC) drug products intended for oral ingestion shall contain the magnesium...

  3. 21 CFR 184.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Magnesium hydroxide. 184.1428 Section 184.1428... Listing of Specific Substances Affirmed as GRAS § 184.1428 Magnesium hydroxide. (a) Magnesium hydroxide... is prepared as a white precipitate by the addition of sodium hydroxide to a water soluble...

  4. 21 CFR 582.1425 - Magnesium carbonate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Magnesium carbonate. 582.1425 Section 582.1425 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1425 Magnesium carbonate. (a) Product. Magnesium carbonate. (b) Conditions of use....

  5. Synthesis Of Superconducting Magnesium Diboride Objects.

    DOEpatents

    Finnemore, Douglas K.; Canfield, Paul C.; Bud'ko, Sergey L.; Ostenson, Jerome E.; Petrovic, Cedomir; Cunningham, Charles E.; Lapertot, Gerard

    2003-07-08

    A process to produce magnesium diboride objects from boron objects with a similar form is presented. Boron objects are reacted with magnesium vapor at a predetermined time and temperature to form magnesium diboride objects having a morphology similar to the boron object's original morphology.

  6. 21 CFR 582.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Magnesium hydroxide. 582.1428 Section 582.1428 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1428 Magnesium hydroxide. (a) Product. Magnesium hydroxide. (b) Conditions of use....

  7. 21 CFR 582.2437 - Magnesium silicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium silicate. 582.2437 Section 582.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations,...

  8. 21 CFR 582.1431 - Magnesium oxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Magnesium oxide. 582.1431 Section 582.1431 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1431 Magnesium oxide. (a) Product. Magnesium oxide. (b) Conditions of use. This substance...

  9. 21 CFR 582.1431 - Magnesium oxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Magnesium oxide. 582.1431 Section 582.1431 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1431 Magnesium oxide. (a) Product. Magnesium oxide. (b) Conditions of use. This substance...

  10. 21 CFR 582.1425 - Magnesium carbonate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Magnesium carbonate. 582.1425 Section 582.1425 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1425 Magnesium carbonate. (a) Product. Magnesium carbonate. (b) Conditions of use....

  11. 21 CFR 582.2437 - Magnesium silicate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Magnesium silicate. 582.2437 Section 582.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations,...

  12. 21 CFR 582.1425 - Magnesium carbonate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Magnesium carbonate. 582.1425 Section 582.1425 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1425 Magnesium carbonate. (a) Product. Magnesium carbonate. (b) Conditions of use....

  13. 21 CFR 582.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Magnesium hydroxide. 582.1428 Section 582.1428 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1428 Magnesium hydroxide. (a) Product. Magnesium hydroxide. (b) Conditions of use....

  14. Development of a Fundamental Understanding of Chemical Bonding and Electronic Structure in Spinel Compounds

    SciTech Connect

    Sickafus, K.E.; Wills, J.M.; Chen, S.-P.; Terry, J.H., Jr.; Hartmann, T.; Sheldon, R.I.

    1999-05-14

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos national Laboratory (LANL). Hundreds of ceramic compounds possess the spinel crystal structure and exhibit a remarkable variety of properties, ranging from compounds that are electrical insulators to compounds that are superconducting, or from compounds with ferri- and antiferromagnetic behavior to materials with colossal magnetoresistive characteristics. The unique crystal structure of spinel compounds is in many ways responsible for the widely varying physical properties of spinels. The objective of this project is to investigate the nature of chemical bonding, point defects, and electronic structure in compounds with the spinel crystal structure. Our goal is to understand and predict the stability of the spinel structure as a function of chemical composition, stoichiometry, and cation disorder. The consequences of cation disorder in spinel materials can be profound . The ferromagnetic characteristics of magnesioferrite, for instance, are entirely attributable to disorder on the cation sublattices. Our studies provide insight into the mechanisms of point defect formation and cation disorder and their effects on the electronic band structure and crystal structure of spinel-structure materials. our ultimate objective is to develop a more substantive knowledge of the spinel crystal structure and to promote new and novel uses for spinel compounds. The technical approach to achieve our goals is to combine first-principles calculations with experimental measurements. The structural and electronic properties of spinel samples were experimentally determined primarily with X-ray and neutron scattering, optical and X-ray absorption, and electron energy-loss spectroscopy. Total energy electronic structure calculations were performed to determine structural stability, band structure, density of states, and electron distribution. We also used shell

  15. Development of a Fundamental Understanding of Chemical Bonding and Electronic Structure in Spinel Compounds

    SciTech Connect

    Sickafus, K.E.; Wills, J.M.; Chen, S.-P.; Terry, J.H., Jr.; Hartmann, T.; Sheldon, R.I.

    1999-06-03

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Hundreds of ceramic compounds possess the spinel crystal structure and exhibit a remarkable variety of properties, ranging from compounds that are electrical insulators to compounds that are superconducting, or from compounds with ferri- and antiferromagnetic behavior to materials with colossal magnetoresistive characteristics. The unique crystal structure of spinel compounds is in many ways responsible for the widely varying physical properties of spinels. The objective of this project is to investigate the nature of chemical bonding, point defects, and electronic structure in compounds with the spinel crystal structure. Our goal is to understand and predict the stability of the spinel structure as a function of chemical composition, stoichiometry, and cation disorder. The consequences of cation disorder in spinel materials can be profound . The ferromagnetic characteristics of magnesioferrite, for instance, are entirely attributable to disorder on the cation sublattices. Our studies provide insight into the mechanisms of point defect formation and cation disorder and their effects on the electronic band structure and crystal structure of spinel-structure materials. Our ultimate objective is to develop a more substantive knowledge of the spinel crystal structure and to promote new and novel uses for spinel compounds. The technical approach to achieve our goals is to combine first-principles calculations with experimental measurements. The structural and electronic properties of spinel samples were experimentally determined primarily with X-ray and neutron scattering, optical and X-ray absorption, and electron energy-loss spectroscopy. Total energy electronic structure calculations were performed to determine structural stability, band structure, density of states, and electron distribution. We also used shell

  16. Effect of aluminum phosphide on blood glucose level.

    PubMed

    Abder-Rahman, H

    1999-02-01

    Aluminum phosphide (AlP), a poison extensively used as a grain fumigant and rodenticide, can cause an increase or decrease in blood glucose levels Both hypo- and hyper-glycemic effects of AlP can be attributed to the wide variety of changes in magnesium, calcium, phosphate, citrate and cortisol levels. These biochemical changes can act as active stimulatory or inhibitory modulators to enzymes and hormones that catalyze and regulate glucose metabolism. According to the type of biochemical changes, AlP can cause either elevation, decrease or no change in blood glucose levels. A case of AlP-caused death is reported.

  17. A Spinel Oxynitride with Visible-Light Photocatalytic Activity

    SciTech Connect

    Boppana, V.; Doren, D; Lobo, R

    2010-01-01

    Spinel zinc gallium oxynitride photocatalysts are prepared by the sol-gel method, at 550 C. In these materials, of base composition ZnGa{sub 2}O{sub 4} (octahedral Ga), reaction with ammonia leads to ZnGa{sub 2}O{sub x}N{sub y}, with a dramatic reduction of the bandgap to 2.7 eV, with just 1.3% N and no loss of Zn. At 850 C this phase is converted into wurzite (tetrahedral Ga). The novel oxynitrides also show visible-light photocatalytic activity towards the degradation of methylene blue.

  18. An Oxygen Electrode Based on Nickel/Cobalt Spinel,

    DTIC Science & Technology

    1981-07-01

    RESUME On a d~montr6 la formation de l oxyde mixte de cadmium et de nickel du type "spinelle" par ]a d~coposition thermique du nitrate de cadmium se...3). Metal oxide catalysts of the spinel or perovskite structure offer the possibility of high catalytic activity and extended life under a variety of...operating conditions. Tseung and co-workers (4,5) have shown that perovskite oxide electrodes prepared by doping LaCoU 3 with strontium perform

  19. Aluminum, parathyroid hormone, and osteomalacia

    SciTech Connect

    Burnatowska-Hledin, M.A.; Kaiser, L.; Mayor, G.H.

    1983-01-01

    Aluminum exposure in man is unavoidable. The occurrence of dialysis dementia, vitamin D-resistant osteomalacia, and hypochromic microcytic anemia in dialysis patients underscores the potential for aluminum toxicity. Although exposure via dialysate and hyperalimentation leads to significant tissue aluminum accumulation, the ubiquitous occurrence of aluminum and the severe pathology associated with large aluminum burdens suggest that smaller exposures via the gastrointestinal tract and lungs could represent an important, though largely unrecognized, public health problem. It is clear that some aluminum absorption occurs with the ingestion of small amounts of aluminum in the diet and medicines, and even greater aluminum absorption is seen in individuals consuming large amounts of aluminum present in antacids. Aluminum absorption is enhanced in the presence of elevated circulating parathyroid hormone. In addition, elevated PTH leads to the preferential deposition of aluminum in brain and bone. Consequently, PTH is likely to be involved in the pathogenesis of toxicities in those organs. PTH excess also seems to lead to the deposition of aluminum in the parathyroid gland. The in vitro demonstration that aluminum inhibits parathyroid hormone release is consistent with the findings of a euparathyroid state in dialysis patients with aluminum related vitamin D-resistant osteomalacia. Nevertheless, it seems likely that hyperparathyroidism is at least initially involved in the pathogenesis of aluminum neurotoxicity and osteomalacia; the increases in tissue aluminum stores are followed by suppression of parathyroid hormone release, which is required for the evolution of osteomalacia. Impaired renal function is not a prerequisite for increased tissue aluminum burdens, nor for aluminum-related organ toxicity. Consequently, it is likely that these diseases will be observed in populations other than those with chronic renal disease.

  20. Unintentional poisoning by phosphine released from aluminum phosphide.

    PubMed

    Shadnia, S; Mehrpour, O; Abdollahi, M

    2008-01-01

    Aluminum phosphide as a releaser of phosphine gas is used as a grain preservative. In this case report, we describe an accidental severe poisoning in a 35-year-old woman, her 18-year-old daughter, and 6-year-old son caused by inhalation of phosphine gas released from 20 tablets of aluminum phosphide stored in 15 rice bags. The boy died 2 days after exposure before admission to hospital and any special treatment, but the others were admitted 48 h after exposure. They had signs and symptoms of severe toxicity, and their clinical course included metabolic acidosis, electrocardiographic changes, and hypotension. They were treated by intravenous administration of sodium bicarbonate, magnesium sulfate, and calcium gluconate. The patients were discharged after 3 days and followed up for 1 week after discharge. Rapid absorption of phosphine by inhalation, induction of hyperglycemia, and surviving of patients are interesting issues of this case report.

  1. Reduction of Viologen Bisphosphonate Dihalide with Aluminum Foil

    NASA Astrophysics Data System (ADS)

    Abeta Iyere, Peter

    1996-05-01

    An elegant undergraduate experiment similar to the popular "Iodine Clock Reaction" employs the reduction of methyl viologen by hydroxide ion. A major problem with the hydroxide reduction demonstration is that the mechanism is complicated by the existence of competing reaction pathways. It has been suggested that layered metal viologen phosphonates could be used in the design and construction of molecular materials. The active unit in the reversible photocoloration of these layered materials is the viologen bisphosphonate dihalide (VPX). During our study of these phoshponate systems, we discovered the reduction of viologen bisphosphonate dihalide by aluminum foil, mossy zinc, or magnesium turnings in dilute aqueous hydrofluoric acid solution. When we demonstrated this phenomenon with aluminum foil and VPBr in the classroom, the response of our students was enthusiastic. This demonstration can be used as prelaboratory discussion for an undergraduate kinetic experiment based on the same phenomenon.

  2. Impact Toughness and Heat Treatment for Cast Aluminum

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A (Inventor)

    2016-01-01

    A method for transforming a cast component made of modified aluminum alloy by increasing the impact toughness coefficient using minimal heat and energy. The aluminum alloy is modified to contain 0.55%-0.60% magnesium, 0.10%-0.15% titanium or zirconium, less than 0.07% iron, a silicon-tomagnesium product ratio of 4.0, and less than 0.15% total impurities. The shortened heat treatment requires an initial heating at 1,000deg F. for up to I hour followed by a water quench and a second heating at 350deg F. to 390deg F. for up to I hour. An optional short bake paint cycle or powder coating process further increase.

  3. Magnesium Diboride Current Leads

    NASA Technical Reports Server (NTRS)

    Panek, John

    2010-01-01

    A recently discovered superconductor, magnesium diboride (MgB2), can be used to fabricate conducting leads used in cryogenic applications. Dis covered to be superconducting in 2001, MgB2 has the advantage of remaining superconducting at higher temperatures than the previously used material, NbTi. The purpose of these leads is to provide 2 A of electricity to motors located in a 1.3 K environment. The providing environment is a relatively warm 17 K. Requirements for these leads are to survive temperature fluctuations in the 5 K and 11 K heat sinks, and not conduct excessive heat into the 1.3 K environment. Test data showed that each lead in the assembly could conduct 5 A at 4 K, which, when scaled to 17 K, still provided more than the required 2 A. The lead assembly consists of 12 steelclad MgB2 wires, a tensioned Kevlar support, a thermal heat sink interface at 4 K, and base plates. The wires are soldered to heavy copper leads at the 17 K end, and to thin copper-clad NbTi leads at the 1.3 K end. The leads were designed, fabricated, and tested at the Forschungszentrum Karlsruhe - Institut foer Technische Physik before inclusion in Goddard's XRS (X-Ray Spectrometer) instrument onboard the Astro-E2 spacecraft. A key factor is that MgB2 remains superconducting up to 30 K, which means that it does not introduce joule heating as a resistive wire would. Because the required temperature ranges are 1.3-17 K, this provides a large margin of safety. Previous designs lost superconductivity at around 8 K. The disadvantage to MgB2 is that it is a brittle ceramic, and making thin wires from it is challenging. The solution was to encase the leads in thin steel tubes for strength. Previous designs were so brittle as to risk instrument survival. MgB2 leads can be used in any cryogenic application where small currents need to be conducted at below 30 K. Because previous designs would superconduct only at up to 8 K, this new design would be ideal for the 8-30 K range.

  4. Ultrasonic Real-Time Quality Monitoring Of Aluminum Spot Weld Process

    NASA Astrophysics Data System (ADS)

    Perez Regalado, Waldo Josue

    The real-time ultrasonic spot weld monitoring system, introduced by our research group, has been designed for the unsupervised quality characterization of the spot welding process. It comprises the ultrasonic transducer (probe) built into one of the welding electrodes and an electronics hardware unit which gathers information from the transducer, performs real-time weld quality characterization and communicates with the robot programmable logic controller (PLC). The system has been fully developed for the inspection of spot welds manufactured in steel alloys, and has been mainly applied in the automotive industry. In recent years, a variety of materials have been introduced to the automotive industry. These include high strength steels, magnesium alloys, and aluminum alloys. Aluminum alloys have been of particular interest due to their high strength-to-weight ratio. Resistance spot welding requirements for aluminum vary greatly from those of steel. Additionally, the oxide film formed on the aluminum surface increases the heat generation between the copper electrodes and the aluminum plates leading to accelerated electrode deterioration. Preliminary studies showed that the real-time quality inspection system was not able to monitor spot welds manufactured with aluminum. The extensive experimental research, finite element modelling of the aluminum welding process and finite difference modeling of the acoustic wave propagation through the aluminum spot welds presented in this dissertation, revealed that the thermodynamics and hence the acoustic wave propagation through an aluminum and a steel spot weld differ significantly. For this reason, the hardware requirements and the algorithms developed to determine the welds quality from the ultrasonic data used on steel, no longer apply on aluminum spot welds. After updating the system and designing the required algorithms, parameters such as liquid nugget penetration and nugget diameter were available in the ultrasonic data

  5. Rhenium and Iridium Partitioning in Silicate and Magmatic Spinels: Implications for Planetary Magmatism and Mantles

    NASA Technical Reports Server (NTRS)

    Righter, K.

    2001-01-01

    Highly siderophile elements Re, Ru and Ir partition strongly into spinel structures with large octahedral sites. New experimental results for both magmatic and silicate spinels will be presented with a few planetary implications. Additional information is contained in the original extended abstract.

  6. Fatal aluminum phosphide poisoning.

    PubMed

    Anger, F; Paysant, F; Brousse, F; Le Normand, I; Develay, P; Gaillard, Y; Baert, A; Le Gueut, M A; Pepin, G; Anger, J P

    2000-03-01

    A 39-year-old man committed suicide by ingestion of aluminum phosphide, a potent mole pesticide, which was available at the victim's workplace. The judicial authority ordered an autopsy, which ruled out any other cause of death. The victim was discovered 10 days after the ingestion of the pesticide. When aluminum phosphide comes into contact with humidity, it releases large quantities of hydrogen phosphine (PH3), a very toxic gas. Macroscopic examination during the autopsy revealed a very important asphyxia syndrome with major visceral congestion. Blood, urine, liver, kidney, adrenal, and heart samples were analyzed. Phosphine gas was absent in the blood and urine but present in the brain (94 mL/g), the liver (24 mL/g), and the kidneys (41 mL/g). High levels of phosphorus were found in the blood (76.3 mg/L) and liver (8.22 mg/g). Aluminum concentrations were very high in the blood (1.54 mg/L), brain (36 microg/g), and liver (75 microg/g) compared to the usual published values. Microscopic examination revealed congestion of all the organs studied and obvious asphyxia lesions in the pulmonary parenchyma. All these results confirmed a diagnosis of poisoning by aluminum phosphide. This report points out that this type of poisoning is rare and that hydrogen phosphine is very toxic. The phosphorus and aluminum concentrations observed and their distribution in the different viscera are discussed in relation to data in the literature.

  7. Silica and aluminum in drinking water and cognitive impairment in the elderly.

    PubMed

    Jacqmin-Gadda, H; Commenges, D; Letenneur, L; Dartigues, J F

    1996-05-01

    We studied the relation between silica and aluminum levels in drinking water and the risk of cognitive impairment using data from a population-based survey of 3,777 French subjects age 65 years and older. We also studied the effect of pH and the concentrations of calcium, magnesium, fluorine, zinc, copper, and iron. We used a mixed effects logistic regression adjusting for age, sex, educational level, and occupation of the subjects. We confirmed the inverse relation previously found between calcium level and cognitive impairment. We found no important association between cognitive impairment and fluorine, magnesium, iron, copper, or zinc. The association between cognitive impairment and aluminum depended on the pH and the concentration of silica: high levels of aluminum appeared to have a deleterious effect when the silica concentration was low, but there was a protective effect when the pH and the silica level were high. The threshold for an aluminum effect, however, was very low (3.5 micrograms per liter) and did not support the hypothesis of a deleterious effect for only high levels of aluminum.

  8. Major Minerals - Calcium, Magnesium, Phosphorus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Calcium, magnesium and phosphorus are essential elements critically important for the function of the musculoskeletal system, including the formation and transduction of energy and the maintenance of healthy bone. The major calcium concern for physically active healthy middle-aged adults is to consu...

  9. The aluminium-scandium-lithium-magnesium system as a potential source of superplastically formable alloys

    SciTech Connect

    Emigh, R.A.

    1990-07-01

    Alloys from the aluminum-lithium-scandium-magnesium system have been cast and rolled for study. The goal is to evaluate this system for the development of superplastically formable, high strength alloys. Aluminum-scandium-magnesium alloys have shown potential as superplastic alloys. These alloys rely on small Al{sub 3}Sc (ordered L1{sub 2}) precipitates for grain structure stabilization and strengthening. Additional precipitation strengthening is required to raise their strength to levels sufficient for aircraft applications. The addition of lithium provides this additional strengthening through the formation of Al{sub 3}Li({delta}{prime}). To produce the alloys studied in this research, a unique induction melting furnace was constructed that incorporates special features to produce aluminum-lithium alloys with low hydrogen content. The furnace also features a water cooled, copper casting mold to achieve a moderately rapid solidification rate. This is because the amount of scandium used (0.5 wt %) is in excess of the solubility limit and Al{sub 3}Sc cannot be re-solutionized to any extent. It is therefore desired to super-saturate the matrix with as much scandium as possible for later precipitation. Two high lithium alloys were produced, ALS2 (nominal composition Al-2.2Li-O.5 Sc) and AlS4 (nominal composition Al-2.0Li-2.2Mg-0.5Sc) that were strengthened with {delta}{prime} (Al{sub 3}Li). These alloys exhibited strength and ductility superior to those of aluminum-lithium-(magnesium)-zirconium alloys. This is because the scandium containing alloys have developed a finer grain structure and the Al{sub 3}Sc precipitates contribute to the alloys strength. 41 refs., 29 figs.

  10. Formation of spinels in the mesosphere after K/T impact

    NASA Astrophysics Data System (ADS)

    Preisinger, A.; Aslanian, S.; Brandstaetter, F.; Grass, F.

    1997-03-01

    Continuous Cretaceous/Tertiary (K/T) boundary sections were studied in the eastern Balkan Mountains at the Black Sea coast near Bjala, Bulgaria, in the Scaglia Rossa of the Apennines, 25 km north of Gubbio at Cerrara, Italy, and in the Betic Zone in the Barranco del Gredero near Caravaca, Spain. Spinels were extracted with a strong magnet from water suspensions of clays sampled stepwise at intervals of a few millimeters from the K/T boundaries and were investigated by X-ray powder diffraction, SEM, EDS, and instrumental neutron activation analysis. Spinels from the east-west range of the Mediterranean area of 3000 km (Bjala-Caravaca) have structural and chemical compositions which are characteristic of the KT-spinels of the boundary clay sites. The majority of these KT-spinels are single crystals of Ni-rich magnesioferrite spinels of octahedral shape of 1-20 micron in sizes.

  11. Crystallization of Pyroxene and Spinel in Gabbroic Lunar Meteorite Asuka 881757

    NASA Astrophysics Data System (ADS)

    Arai, T.; Takeda, H.; Warren, P. H.

    1995-09-01

    Lunar meteorite Asuka (A)881757 is a distinct new type of low-Ti (LT) mare basalt [e.g. 1,2], considerably older than nearly all Apollo and Luna mare basalt samples [3], and may be an product of the earliest mare volcanism. It shows an extraordinarily coarse-grained gabbroic texture, and is mainly composed of Fe-rich pyroxene, plagioclase, olivine, ilmenite, Ti-rich spinel, troilite and Fe-Ni [4]. Extensive chemical zonings, which are recognized in pyroxenes and spinels, were studied by means of elemental distribution maps in order to deduce crystallization condition of pyroxene and spinel, and their mutual relationship during crystallization. We studied polished thin sections (PTS) A881757, 51-4, A881757, 53D-2, and A881757, 53E-2 supplied by the National Institute of Polar Research (NIPR). Mineral chemistries and textures were examined by EPMA and SEM. Elemental distribution maps of pyroxenes and spinels for Fe, Mg, Ti, Cr, and Al were obtained by EPMA. Pyroxenes are generally zoned from Mg-rich core Fe(sub)37Mg(sub)40Ca(sub)23 to Fe-rich rim Fe(sub)65Mg(sub)10Ca(sub)25 in three PTSs. Spinels are distributed quite heterogeneously through three PTS and modal abundance of spinel reachs 11% only in one PTS. Spinels in three PTS can be divided in two groups: spinels in mesostases and interstitial ones between pyroxenes. Mesostasis spinels, which are homogeneous and have similar compositions from grain to grain, crystallized with very Fe-rich pyroxene. Interstitial spinels which are zoned for TiO2 and Cr2O3 within crystals, and show different composition between crystals, cocrystallized with relatively Mg- rich pyroxenes. Interstitial spinels (TiO2= 23-28wt%, Cr2O3= 8-17 wt%) are more Ti-rich and less Cr-rich than mesostasis ones (TiO2= 30-31wt%, Cr2O3= 3-4 wt%). It is noted that more Ti-rich spinels tend to be surrounded by more Fe-rich pyroxene. Spinels in mare basalts generally change their compositions from Fe2TiO4 (ulvospinel) to FeCr2O4 (chromite) during

  12. Hierarchical surface atomic structure of a manganese-based spinel cathode for lithium-ion batteries.

    PubMed

    Lee, Sanghan; Yoon, Gabin; Jeong, Minseul; Lee, Min-Joon; Kang, Kisuk; Cho, Jaephil

    2015-01-19

    The increasing use of lithium-ion batteries (LIBs) in high-power applications requires improvement of their high-temperature electrochemical performance, including their cyclability and rate capability. Spinel lithium manganese oxide (LiMn2O4) is a promising cathode material because of its high stability and abundance. However, it exhibits poor cycling performance at high temperatures owing to Mn dissolution. Herein we show that when stoichiometric lithium manganese oxide is coated with highly doped spinels, the resulting epitaxial coating has a hierarchical atomic structure consisting of cubic-spinel, tetragonal-spinel, and layered structures, and no interfacial phase is formed. In a practical application of the coating to doped spinel, the material retained 90% of its capacity after 800 cycles at 60 °C. Thus, the formation of an epitaxial coating with a hierarchical atomic structure could enhance the electrochemical performance of LIB cathode materials while preventing large losses in capacity.

  13. Origin of spinel-rich chondrules and inclusions in carbonaceous and ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Kornacki, A. S.; Fegley, B., Jr.

    1984-01-01

    The evaluation of three models of the origin of spinel-rich chondrules and inclusions presented here includes new calculations of the major-element refractory mineral condensation sequence from a gas of solar composition over a wide pressure interval. Condensation calculations show that spinel-rich chondrules did not crystallize from metastable liquid condensates, and that spinel-rich inclusions are not aggregates of refractory nebular condensates. It is proposed that spinel-rich objects are fractionated distillation residues of small aggregates of primitive dust that lost Ca, Si-rich partial melts by evaporation, ablation, or splashing during collisions. This model also explains why spinel-rich chondrules and inclusions (1) are usually smaller than melilite-rich chondrules and inclusions; (2) often have highly fractionated trace-element compositions; and (3) usually do not contain Pt-metal nuggets even when they are more enriched in the Pt-group metals than nugget-bearing melilite-rich objects.

  14. Non-isothermal Crystallization Kinetics of Spinels in Vanadium Slag with High CaO Content

    NASA Astrophysics Data System (ADS)

    Zhou, Wang; Xie, Bing; Tan, Wen-Feng; Diao, Jiang; Zhang, Xie; Li, Hong-Yi

    2016-09-01

    This paper investigated the non-isothermal crystallization kinetics of the spinel crystals in vanadium slags containing high CaO content. Experiments were performed in combination with theoretical calculation to address this issue, and statistical analyses based on the Crystal Size Distribution theory. The results indicate that low cooling rate and high CaO content benefit the growth of spinel crystals. The growth mechanism is revealed to be controlled by interface reactions and diffusion at the cooling rates of 5 K/min and 15 K/min, respectively. However, at higher temperatures (>1673 K), the growth of spinel crystals is controlled by nucleation. While the temperature is decreased to 1523 K at the cooling rate of 5 K/min, the mean diameter of spinel crystals could reach 36.44 μm. Experimental results combining with theoretical reveal that low cooling rate benefits spinels growth, especially for the interval of 1523 K-1200 K.

  15. A SEARCH FOR MAGNESIUM IN EUROPA'S ATMOSPHERE

    SciTech Connect

    Hoerst, S. M.; Brown, M. E.

    2013-02-20

    Europa's tenuous atmosphere results from sputtering of the surface. The trace element composition of its atmosphere is therefore related to the composition of Europa's surface. Magnesium salts are often invoked to explain Galileo Near Infrared Mapping Spectrometer spectra of Europa's surface, thus magnesium may be present in Europa's atmosphere. We have searched for magnesium emission in the Hubble Space Telescope Faint Object Spectrograph archival spectra of Europa's atmosphere. Magnesium was not detected and we calculate an upper limit on the magnesium column abundance. This upper limit indicates that either Europa's surface is depleted in magnesium relative to sodium and potassium, or magnesium is not sputtered as efficiently resulting in a relative depletion in its atmosphere.

  16. A RELICT Spinel Grain in an Allende Ferromagnesian Chondrule

    NASA Astrophysics Data System (ADS)

    Misawa, K.; Fujita, T.; Kitamura, M.; Nakamura, N.; Yurimoto, H.

    1993-07-01

    It is suggested that one of the refractory lithophile precursors in CV-CO chondrules was a hightemperature condensate from the nebular gas and was related to Ca,Al-rich inclusions (CAIs) [1-3]. However, little is known about refractory siderophile precursors in chondrules [4]. Allende barred olivine chondrule R-11 consists mainly of olivine (Fa(sub)7- 18), pyroxene (En(sub)93Fs(sub)1Wo(sub)6, En(sub)66Fs(sub)1Wo(sub)33), plagioclase (An(sub)80), Fe-poor spinel, and alkali-rich glass. The CI- chondrite normalized REE pattern of the chondrule, excluding a spinel grain, are fractionated, HREEdepleted (4.6-7.8 x CI) with a large positive Yb anomaly. The REE abundances are hump-shaped functions of elemental volatility, moderately refractory REE-enriched, suggesting that the refractory lithophile precursor component of R-11 could be a condensate from the nebular gas and related to Group 11 CAIs [1,2]. An interior portion of spinel is almost Fe-free, but in an outer zone (2040 micrometers in width) FeO contents increase rapidly. TiO(sub)2, Cr(sub)2O(sub)3, and V(sub)2O(sub)3 contents in core spinel are less than 0.5%, which is different from the V-rich nature of spinel in fluffy Type A CAIs [5]. The Fe-Mg zoning of spinel may have been generated by diffusional emplacement of Mg and Fe during chondrule-forming events. The spinel contains silicate inclusions and tiny metallic grains. The largest silicate inclusion is composed of Al,Ti-rich pyroxene and Ak 40 melilite. One of the submicrometersized grains was analyzed by SEM-EDS and found to be composed of refractory Pt-group metals with minor amounts of Fe and Ni. This is the first occurrence of refractory Pt-group metal nuggets in a ferromagnesian chondrule from the Allende meteorite. Tungsten, Os, Ir, Mo, and Ru are enriched 2-6 x 10^5 relative to CIs, and abundances of Pt and Rh decrease 2-10 x 10^4 with increasing volatility. In addition, abundances of Fe and Ni in the nugget are equal to or less than that CI chondrites

  17. Hydrothermal spinel, corundum and diaspore in lower oceanic crustal troctolites from the Hess Deep Rift

    NASA Astrophysics Data System (ADS)

    Nozaka, Toshio; Meyer, Romain; Wintsch, Robert P.; Wathen, Bryan

    2016-06-01

    Aluminous spinel, corundum and diaspore are reported from intensely altered parts of primitive troctolites recovered from IODP Site U1415 at the Hess Deep Rift. The spinel is green-colored, has an irregular shape, has low Cr concentrations, and is so distinct from primary igneous chromite. Corundum and diaspore occur mainly at the rims of green spinel grains with a texture suggesting a sequential replacement of spinel by corundum, and then corundum by diaspore. The green spinel is associated with anorthite and pargasite, which is overgrown by tremolite that forms coronitic aggregates with chlorite around olivine. These petrographic observations are supported by pressure-temperature pseudosections, which predict spinel + pargasite stability field, and tremolite/hornblende + chlorite field at lower temperature conditions. From these pseudosections and simplified system phase diagrams, estimated formation temperature conditions calculated at 2 kbar are 650-750 °C for spinel + pargasite, 410-690 °C for tremolite/hornblende + chlorite, 400-710 °C for corundum, and <400 °C for diaspore. Because the aluminous spinel occurs in the domains that were previously occupied by magmatic plagioclase, and because spinel-bearing rocks characteristically have high Al2O3/CaO and Al2O3/SiO2 ratios, it is likely that the stabilization of spinel was caused by the loss of Ca2+ and SiO2(aq) in high-temperature hydrothermal fluids. The results of this study suggest that (1) the concentrations of aluminous phases in the lower oceanic crust are presently underestimated, and (2) chemical modification of the lower oceanic crust due to high-temperature hydrothermal metasomatic reactions could be common near spreading axes.

  18. Origin and significance of spinel pyroxene symplectite in lherzolite xenoliths from Tallante, SE Spain

    NASA Astrophysics Data System (ADS)

    Shimizu, Yohei; Arai, Shoji; Morishita, Tomoaki; Ishida, Yoshito

    2008-09-01

    We found spinel pyroxene symplectites in lherzolite xenoliths from Tallante, SE Spain, and investigated their petrographical and geochemical signatures. The spinel pyroxene symplectites are divided into two types, a spinel-type (= opx + cpx + sp) and a plagioclase-type (= opx + cpx + sp + pl) symplectites. The symplectites are always surrounded by lenticular aggregates of coarser-grained spinel pyroxene. The petrography and major-element chemistry of bulk symplectites indicate an origin through subsolidus reaction between olivine and garnet like at Horoman (Japan; Morishita and Arai, Contrib Mineral Petrol 144:509 522, 2003). The spinel pyroxene symplectites at Tallante were of garnet origin. However, the bulk Tallante spinel pyroxene symplectites show a relatively flat rare earth element (REE) distribution with slight light REE (LREE) enrichment, i.e. there was no trace-element signature typical of mantle garnet. They also differ from the Horoman symplectites that occasionally preserve a garnet trace-element signature, i.e. depletion of LREE and enrichment of heavy REE. These conflicting results indicate that the symplectites record slight enrichment in pyroxene compositions during or after depletion by melt extraction and breakdown of garnet by decompression, and all the minerals including symplectite constituents have been homogenized in the stability field of spinel to plagioclase lherzolite, with the assistance of some melt (possibly an alkaline silicate melt; Downes, J Petrol 42:233 250, 2001). Moreover, some of the spinel-type symplectites experienced heating by injection of Si-rich melt, and consequently have been transformed to the plagioclase-type symplectite. The Tallante spinel pyroxene symplectites developed from garnet + olivine and were carried from the garnet lherzolite stability field to the spinel and to the plagioclase lherzolite stability fields. Our data indicates mantle upwelling (mantle diapirism) beneath the Betic Rif zone in southern Spain.

  19. Crystallization Kinetics of Calcium-magnesium Aluminosilicate (CMAS) Glass

    NASA Technical Reports Server (NTRS)

    Wiesner, Valerie L.; Bansal, Narottam P.

    2015-01-01

    The crystallization kinetics of a calcium-magnesium aluminosilicate (CMAS) glass with composition relevant for aerospace applications, like air-breathing engines, were evaluated using differential thermal analysis (DTA) in powder and bulk forms. Activation energy and frequency factor values for crystallization of the glass were evaluated. X-ray diffraction (XRD) was used to investigate the onset of crystallization and the phases that developed after heat treating bulk glass at temperatures ranging from 690 to 960 deg for various times. Samples annealed at temperatures below 900 deg remained amorphous, while specimens heat treated at and above 900 deg exhibited crystallinity originating at the surface. The crystalline phases were identified as wollastonite (CaSiO3) and aluminum diopside (Ca(Mg,Al) (Si,Al)2O6). Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were employed to examine the microstructure and chemical compositions of crystalline phases formed after heat treatment.

  20. A new integrated lean manufacturing model for magnesium products

    NASA Astrophysics Data System (ADS)

    D'Errico, F.; Perricone, G.; Oppio, R.

    2009-04-01

    From an environmental point of view, lighter metals like aluminum and magnesium are unclean products to make; they require energy-intensive methods and increased greenhouse gas emissions as compared with steels. They are, however, clean to use, in particular in the transportation sector, if adequate weight savings and consequent fuel consumption reduction and CO2 reduction can be achieved to offset the initial higher energy need. In order to reduce CO2 emissions, better energy efficiency and substitution of low-carbon technologies are going to play a key role in future technical options. Modern research and development should be focused on promoting the efficient use of metallic materials according to the “dematerialization” concept design.

  1. Design of experimentation with a platinum-magnesium bioelectric battery.

    PubMed

    Fontenier, G; Freschard, R; Mourot, M

    1975-01-01

    The utilization of metal electrodes in the fabrication of a bioelectric battery has been the subject of intensive study for several years. Up to this date, subcutaneous cathodes of black platinum or of silver-silver chloride have been used in conjunction with anodes of aluminum or zinc. The subcutaneous black platinum is not reliable as a function of time due to the growth of overlying heterogeneous tissues. The utilization of a smooth platinum cathode in the right endoauricular position allows good reliability with time, but does not allow using a large surface area. Furthermore we have a reduction of the H-+ ions and not of the oxygen. A pure Domal magnesium anode was utilized with this cathode, which seemed to be a good compromise between to battery's voltage, its lifetime, and its lack of toxicity to body tissues.

  2. Regeneration of aluminum hydride

    DOEpatents

    Graetz, Jason Allan; Reilly, James J; Wegrzyn, James E

    2012-09-18

    The present invention provides methods and materials for the formation of hydrogen storage alanes, AlH.sub.x, where x is greater than 0 and less than or equal to 6 at reduced H.sub.2 pressures and temperatures. The methods rely upon reduction of the change in free energy of the reaction between aluminum and molecular H.sub.2. The change in free energy is reduced by lowering the entropy change during the reaction by providing aluminum in a state of high entropy, and by increasing the magnitude of the change in enthalpy of the reaction or combinations thereof.

  3. Regeneration of aluminum hydride

    DOEpatents

    Graetz, Jason Allan; Reilly, James J.

    2009-04-21

    The present invention provides methods and materials for the formation of hydrogen storage alanes, AlH.sub.x, where x is greater than 0 and less than or equal to 6 at reduced H.sub.2 pressures and temperatures. The methods rely upon reduction of the change in free energy of the reaction between aluminum and molecular H.sub.2. The change in free energy is reduced by lowering the entropy change during the reaction by providing aluminum in a state of high entropy, by increasing the magnitude of the change in enthalpy of the reaction or combinations thereof.

  4. Structural, dielectric and magnetic behavior of nanocrystalline zinc substituted magnesium ferrite

    SciTech Connect

    Jyoti, Parashar, Jyoti; Saxena, V. K.; Dolia, S. N.; Bhatnagar, D.; Kumar, S.; Sharma, K. B.

    2015-06-24

    Zinc substituted magnesium ferrites Zn{sub 0.2}Mg{sub 0.8}Fe{sub 2}O{sub 4} and Zn{sub 0.4}Mg{sub 0.6}Fe{sub 2}O{sub 4} were prepared by sol-gel auto combustion method. Rietveld profile refinement of the XRD patterns confirms the formation of a cubic spinel structure in single phase. The dielectric properties viz. dielectric constant and dielectric loss tangent tanδ increase with increasing temperature. The dielectric behavior is explained by using the mechanism of polarization process, which is correlated to that of electron exchange interaction. The saturation magnetization, coercivity and remanent magnetization decreases appreciably with increase in Zn which could be attributed to change in cation distribution.

  5. PROCESS FOR REMOVING ALUMINUM COATINGS

    DOEpatents

    Flox, J.

    1959-07-01

    A process is presented for removing aluminum jackets or cans from uranium slugs. This is accomplished by immersing the aluminum coated uranium slugs in an aqueous solution of 9 to 20% sodium hydroxide and 35 to 12% sodium nitrate to selectively dissolve the aluminum coating, the amount of solution being such as to obtain a molar ratio of sodium hydroxide to aluminum of at least

  6. Electrically conductive anodized aluminum coatings

    NASA Technical Reports Server (NTRS)

    Alwitt, Robert S. (Inventor); Liu, Yanming (Inventor)

    2001-01-01

    A process for producing anodized aluminum with enhanced electrical conductivity, comprising anodic oxidation of aluminum alloy substrate, electrolytic deposition of a small amount of metal into the pores of the anodized aluminum, and electrolytic anodic deposition of an electrically conductive oxide, including manganese dioxide, into the pores containing the metal deposit; and the product produced by the process.

  7. 75 FR 22109 - Aluminum Extrusions from the People's Republic of China: Initiation of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-27

    ... designations are representative of aluminum alloys for casting: 208.0, 295.0, 308.0, 355.0, C355.0, 356.0, A356... the major alloying element, with manganese accounting for not more than 3.0 percent of total materials... magnesium accounting for at least 0.1 percent but not more than 2.0 percent of total materials by......

  8. Beta Decay Study of Neutron-rich Magnesium

    NASA Astrophysics Data System (ADS)

    Ash, John; Rajabali, Mustafa; Griffin Collaboration

    2015-10-01

    Within the ``island of inversion'' around the N = 20 shell gap, isotopes of magnesium, and aluminum deviate from the expected closed-shell structure. Particles promoted across the N = 20 shell gap result in a lower energy deformed ground state configuration rather than the expected spherical configuration. An experiment was conducted at TRIUMF laboratory in the summer of 2015 to study the decay of ``island of inversion'' isotopes 33 , 34 , 35Mg and the structure of the respective daughter nuclei. The isotopes of interest were produced by a proton beam from TRIUMF's 500 MeV cyclotron impacting on a UCx target. The magnesium decays populated states along the decay chain in Al, Si, P, and S isotopes. The new GRIFFIN spectrometer in the ISAC-I facility was used to detect the gamma rays. Two sets of scintillators, one for detecting the beta particles (SCEPTAR) and the other for detecting beta-delayed neutrons (DESCANT), were also used in conjunction with GRIFFIN. The GRIFFIN data were energy calibrated and partially analyzed for this project. New algorithms were developed for the analysis. Preliminary results for new transitions detected in 34Mg as well as the half lives obtained will be presented in their current form. This research was supported by the Tennessee Tech research office.

  9. MAGNESIUM PRECIPITATION AND DIFUSSION IN Mg+ ION IMPLANTED SILICON CARBIDE

    SciTech Connect

    Jiang, Weilin; Jung, Hee Joon; Kovarik, Libor; Wang, Zhaoying; Roosendaal, Timothy J.; Zhu, Zihua; Edwards, Danny J.; Hu, Shenyang Y.; Henager, Charles H.; Kurtz, Richard J.; Wang, Yongqiang

    2015-03-02

    As a candidate material for fusion reactor applications, silicon carbide (SiC) undergoes transmutation reactions under high-energy neutron irradiation with magnesium as the major metallic transmutant; the others include aluminum, beryllium and phosphorus in addition to helium and hydrogen gaseous species. Calculations by Sawan et al. predict that at a dose of ~100 dpa (displacements per atom), there is ~0.5 at.% Mg generated in SiC. The impact of these transmutants on SiC structural stability is currently unknown. This study uses ion implantation to introduce Mg into SiC. Multiaxial ion-channeling analysis of the as-produced damage state indicates a lower dechanneling yield observed along the <100> axis. The microstructure of the annealed sample was examined using high-resolution scanning transmission electron microscopy. The results show a high concentration of likely non-faulted tetrahedral voids and possible stacking fault tetrahedra near the damage peak. In addition to lattice distortion, dislocations and intrinsic and extrinsic stacking faults are also observed. Magnesium in 3C–SiC prefers to substitute for Si and it forms precipitates of cubic Mg2Si and tetragonal MgC2. The diffusion coefficient of Mg in 3C–SiC single crystal at 1573 K has been determined to be 3.8 ± 0.4E-19 m2/s.

  10. A New Spinel-Olivine Oxybarometer: Near-Liquidus Partitioning of V between Olivine-Melt, Spinel-Melt, and Spinel-Olivine in Martian Basalt Composition Y980459 as a Function of Oxygen Fugacity

    NASA Technical Reports Server (NTRS)

    Papike, J. J.; Le, L.; Burger, P. V.; Shearer, C. K.; Bell, A. S.; Jones, J.

    2013-01-01

    Our research on valence state partitioning began in 2005 with a review of Cr, Fe, Ti, and V partitioning among crystallographic sites in olivine, pyroxene, and spinel [1]. That paper was followed by several on QUE94201 melt composition and specifically on Cr, V, and Eu partitioning between pyroxene and melt [2-5]. This paper represents the continuation of our examination of the partitioning of multivalent V between olivine, spinel, and melt in martian olivine-phyric basalts of Y980459 composition [6, 7]. Here we introduce a new, potentially powerful oxybarometer, V partitioning between spinel and olivine, which can be used when no melt is preserved in the meteorite. The bulk composition of QUE94201 was ideal for our study of martian pyroxene-phyric basalts and specifically the partitioning between pyroxene-melt for Cr, V, and Eu. Likewise, bulk composition Y980459 is ideal for the study of martian olivine-phyric basalts and specifically for olivine-melt, spinel-melt, and spinel-olivine partitioning of V as a function of oxygen fugacity.

  11. Magnesium: its role in nutrition and carcinogenesis.

    PubMed

    Blaszczyk, Urszula; Duda-Chodak, Aleksandra

    2013-01-01

    Magnesium (Mg2+) plays a key role in many essential cellular processes such as intermediary metabolism, DNA replication and repair, transporting potassium and calcium ions, cell proliferation together with signalling transduction. Dietary sources rich in magnesium are whole and unrefined grains, seeds, cocoa, nuts, almonds and green leafy vegetables. Hard water is also considered to be an important source of magnesium beneficial to human health. The daily dietary intake of magnesium is however frequently found to be below that recommended in Western countries. Indeed, it is recognised that magnesium deficiency may lead to many disorders of the human body, where for instance magnesium depletion is believed to play an important role in the aetiology of the following; cardiovascular disease (including thrombosis, atherosclerosis, ishaemic heart disease, myocardial infarction, hypertension, arrhythmias and congestive heart failure in human), as well as diabetes mellitus, gastrointestinal (GI) tract disease, liver cirrhosis and diseases of the thyroid and parathyroid glands. Insufficient dietary intake of magnesium may also significantly affect the development and exacerbation ofADHD (Attention Deficit- Hyperactivity Disorder) symptoms in children. The known links between magnesium and carcinogenesis still remain unclear and complex, with conflicting results being reported from many experimental, epidemiological and clinical studies; further knowledge is thus required. Mg2+ ions are enzyme cofactors involved in DNA repair mechanisms that maintain genomic stability and fidelity. Any magnesium deficiencies could thereby cause a dysfunction of these systems to occur leading to DNA mutations. Magnesium deficiency may also be associated with inflammation and increased levels of free radicals where both inflammatory mediators and free radicals so arising could cause oxidative DNA damage and therefore tumour formation. The presented review article now provides a summary

  12. REMOVAL OF ALUMINUM COATINGS

    DOEpatents

    Peterson, J.H.

    1959-08-25

    A process is presented for dissolving aluminum jackets from uranium fuel elements without attack of the uranium in a boiling nitric acid-mercuric nitrate solution containing up to 50% by weight of nitrtc acid and mercuric nitrate in a concentration of between 0.05 and 1% by weight.

  13. Markets for recovered aluminum

    SciTech Connect

    Not Available

    1993-04-01

    The study describes the operation of the markets for scrap aluminum as an example of how recycling markets are structured, what factors influence the supply of and demand for materials, what projections can be made about recycling markets, and how government policies to increase recycling may affect these markets.

  14. Building an aluminum car

    SciTech Connect

    Ashley, S.

    1994-05-01

    This article examines the increasing use of aluminum in automobiles to decrease weight and consequently increase fuel economy. The topics of the article include federal fuel economy goals, the development of optimum body structure and manufacturing techniques, comparison with steel, cost of materials, weight reduction and recycling of materials.

  15. Fluxless aluminum brazing

    DOEpatents

    Werner, W.J.

    1974-01-01

    This invention relates to a fluxless brazing alloy for use in forming brazed composites made from members of aluminum and its alloys. The brazing alloy consists of 35-55% Al, 10--20% Si, 25-60% Ge; 65-88% Al, 2-20% Si, 2--18% In; 65--80% Al, 15-- 25% Si, 5- 15% Y. (0fficial Gazette)

  16. Aluminum Sulfate 18 Hydrate

    ERIC Educational Resources Information Center

    Young, Jay A.

    2004-01-01

    A chemical laboratory information profile (CLIP) of the chemical, aluminum sulfate 18 hydrate, is presented. The profile lists physical and harmful properties, exposure limits, reactivity risks, and symptoms of major exposure for the benefit of teachers and students using the chemical in the laboratory.

  17. Bonding aluminum beam leads

    NASA Technical Reports Server (NTRS)

    Burkett, F. S.

    1978-01-01

    Report makes it relatively easy for hybrid-circuit manufacturers to convert integrated circuit chips with aluminum bead leads. Report covers: techniques for handling tiny chips; proper geometries for ultrasonic bonding tips; best combinations of pressure, pulse time, and ultrasonic energy for bonding; and best thickness for metal films to which beam leads are bonded.

  18. designer phase transitions in lithium-based spinels

    SciTech Connect

    Wouter Montfrooij

    2011-09-12

    When electrons in a metal become correlated with each other, new cooperative behavior can arise. This correlation is magnified when the metal has magnetic ions embedded in it. These atomic magnets try to line up with each other, but in doing so actually create a correlation between the motions of conduction electrons. In turn, these correlated electron motions prevent the magnetic ions from aligning, even at zero Kelvin. When this competition is strongest (at the so-called quantum critical point-QCP) the response of the system can no longer be described using the text book theory for metals. In addition, a range of new phenomena has been seen to emerge in the vicinity of a QCP, such as heavy-fermion superconductivity, coexistence of magnetism and superconductivity and hyper-scaling. The main goal of our research is to try to unravel the details of the feedback mechanism between electron motion and magnetism that lies at the heart of this new physics. We have chosen lithium-based spinel structures as the most promising family of systems to achieve our goal. Known lithium-based spinels Li{sub x}M{sub 2}O{sub 4} [M=V, Ti and Mn] show a variety of ground states: heavy-fermion, superconducting, or geometrically frustrated local moment systems. Li{sub x}M{sub 2}O{sub 4} should be ideal systems for studying QCPs since their properties can easily be fine-tuned, simply by extracting some Li [which can be done without introducing disorder in the immediate surroundings of the magnetic ions]. The premise of the proposal was that since this Li-extraction can be done both in the metallic as well as in insulating compounds, that we can expand the types of quantum phase transitions that can be studied to beyond transitions in magnetic metals. The project called for developing a better understanding of quantum phase transitions by measuring all aspects of the electronic response of Li{sub x}M{sub 2}O{sub 4} by means of neutron scattering, giving microscopic information about the

  19. SOLDERING OF ALUMINUM BASE METALS

    DOEpatents

    Erickson, G.F.

    1958-02-25

    This patent deals with the soldering of aluminum to metals of different types, such as copper, brass, and iron. This is accomplished by heating the aluminum metal to be soldered to slightly above 30 deg C, rubbing a small amount of metallic gallium into the part of the surface to be soldered, whereby an aluminum--gallium alloy forms on the surface, and then heating the aluminum piece to the melting point of lead--tin soft solder, applying lead--tin soft solder to this alloyed surface, and combining the aluminum with the other metal to which it is to be soldered.

  20. Thermodynamic modelling of the formation of zinc-manganese ferrite spinel in electric arc furnace dust.

    PubMed

    Pickles, C A

    2010-07-15

    Electric arc furnace dust is generated when automobile scrap, containing galvanized steel, is remelted in an electric arc furnace. This dust is considered as a hazardous waste in most countries. Zinc is a major component of the dust and can be of significant commercial value. Typically, the majority of the zinc exists as zinc oxide (ZnO) and as a zinc-manganese ferrite spinel ((Zn(x)Mn(y)Fe(1-x-y))Fe(2)O(4)). The recovery of the zinc from the dust in metal recycling and recovery processes, particularly in the hydrometallurgical extraction processes, is often hindered by the presence of the mixed ferrite spinel. However, there is a paucity of information available in the literature on the formation of this spinel. Therefore, in the present research, the equilibrium module of HSC Chemistry 6.1 was utilized to investigate the thermodynamics of the formation of the spinel and the effect of variables on the amount and the composition of the mixed ferrite spinel. It is proposed that the mixed ferrite spinel forms due to the reaction of iron-manganese particulates with both gaseous oxygen and zinc, at the high temperatures in the freeboard of the furnace above the steel melt. Based on the thermodynamic predictions, methods are proposed for minimizing the formation of the mixed ferrite spinel.

  1. Spinel-olivine-pryoxene equilibrium iron isotopic fractionation and applications to natural peridotites

    SciTech Connect

    Roskosz, Mathieu; Sio, Corliss K. I.; Dauphas, Nicolas; Bi, Wenli; Tissot, Francois L. H.; Hu, Michael Y.; Zhao, Jiyong; Alp, Esen E.

    2015-11-15

    Eight spinel-group minerals were synthesized by a flux-growth method producing spinels with varying composition and Fe3+/Fe-tot ratios. The mean force constants of iron bonds in these minerals were determined by synchrotron nuclear resonant inelastic X-ray scattering (NRIXS) in order to determine the reduced isotopic partition function ratios (beta-factors) of these spinels. The mean force constants are strongly dependent on the Fe3+/Fe-tot of the spinel but are independent, or weakly dependent on other structural and compositional parameters. From our spectroscopic data, it is found that a single redox-dependent calibration line accounts for the effects of Fe3+/Fe-tot on the beta-factors of spinels. This calibration successfully describes the equilibrium Fe isotopes fractionation factors between spinels and silicates (olivine and pyroxenes). Our predictions are in excellent agreement with independent determinations for the equilibrium Fe isotopic fractionations for the magnetite- fayalite and the magnetite-hedenbergite couples. Our calibration applies to the entire range of Fe3+/Fe-tot ratios found in natural spinels and provides a basis for interpreting iron isotopic variations documented in mantle peridotites. Except for a few exceptions, most of the samples measured so far are in isotopic disequilibrium, reflecting metasomatism and partial melting processes.

  2. Nanostructured hybrid layered-spinel cathode material synthesized by hydrothermal method for lithium-ion batteries.

    PubMed

    Liu, Cong; Wang, Zhiyuan; Shi, Chunsheng; Liu, Enzuo; He, Chunnian; Zhao, Naiqin

    2014-06-11

    Nanostructured spinel LiMn1.5Ni0.5O4, layered Li1.5Mn0.75Ni0.25O2.5 and layered-spinel hybrid particles have been successfully synthesized by hydrothermal methods. It is found that the nanostructured hybrid cathode contains both spinel and layered components, which could be expressed as Li1.13Mn0.75Ni0.25O2.32. Diffraction-contrast bright-field (BF) and dark-field (DF) images illustrate that the hybrid cathode has well dispersed spinel component. Electrochemical measurements reveal that the first-cycle efficiency of the layered-spinel hybrid cathode is greatly improved (up to 90%) compared with that of the layered material (71%) by integrating spinel component. Our investigation demonstrates that the spinel containing hybrid material delivers a high capacity of 240 mAh g(-1) with good cycling stability between 2.0 and 4.8 V at a current rate of 0.1 C.

  3. Method for magnesium sulfate recovery

    DOEpatents

    Gay, Richard L.; Grantham, LeRoy F.

    1987-01-01

    A method of obtaining magnesium sulfate substantially free from radioactive uranium from a slag containing the same and having a radioactivity level of at least about 7000 pCi/gm. The slag is ground to a particle size of about 200 microns or less. The ground slag is then contacted with a concentrated sulfuric acid under certain prescribed conditions to produce a liquid product and a solid product. The particulate solid product and a minor amount of the liquid is then treated to produce a solid residue consisting essentially of magnesium sulfate substantially free of uranium and having a residual radioactivity level of less than 1000 pCi/gm. In accordance with the preferred embodiment of the invention, a catalyst and an oxidizing agent are used during the initial acid treatment and a final solid residue has a radioactivity level of less than about 50 pCi/gm.

  4. Method for magnesium sulfate recovery

    DOEpatents

    Gay, R.L.; Grantham, L.F.

    1987-08-25

    A method is described for obtaining magnesium sulfate substantially free from radioactive uranium from a slag containing the same and having a radioactivity level of at least about 7,000 pCi/gm. The slag is ground to a particle size of about 200 microns or less. The ground slag is then contacted with a concentrated sulfuric acid under certain prescribed conditions to produce a liquid product and a solid product. The particulate solid product and a minor amount of the liquid is then treated to produce a solid residue consisting essentially of magnesium sulfate substantially free of uranium and having a residual radioactivity level of less than 1,000 pCi/gm. In accordance with the preferred embodiment of the invention, a catalyst and an oxidizing agent are used during the initial acid treatment and a final solid residue has a radioactivity level of less than about 50 pCi/gm.

  5. Study on the blood compatibility and biodegradation properties of magnesium alloys.

    PubMed

    Mochizuki, Akira; Kaneda, Hideki

    2015-02-01

    Lately, several magnesium alloys have been investigated as a new class of biomaterials owing to their excellent biodegradability in living tissues. In this study, we considered AZ series of Mg alloy containing aluminum (3% to 9%) and zinc (1%) as a model magnesium alloy, and investigated their biodegradation in whole blood and blood compatibility in vitro. The results of the elution property of metal ions determined using chromogenic assay and the associated pH change show that the degradation resistance of the AZ series alloys in blood is improved by alloying aluminum. Furthermore, the blood compatibility of the alloys was investigated in terms of their hemolysis, factor Xa-like activity, using spectrophotometry and chromogenic assay, respectively, and coagulation time measurements (prothrombin time and activated partial thromboplastin time). The results indicated that the blood compatibility of the AZ series alloys is excellent, irrespective of the alloy composition. The excellent blood compatibility with the coagulation system could be attributed to the eluted Mg(2+) ion, which suppresses the activation of certain coagulation factors in the intrinsic and/or extrinsic coagulation pathways. In terms of the degradation resistance of the AZ series alloys in blood, the results of pH change in blood and the amount of the eluted metal ions indicate that the performance is markedly improved with an increase in aluminum content.

  6. Unresponsive ventricular tachycardia associated with aluminum phosphide poisoning.

    PubMed

    Jadhav, Amar P; Nusair, Maein B; Ingole, Apekshe; Alpert, Martin A

    2012-05-01

    Inhalation or ingestion of aluminum phosphide (AP) generates phosphine gas on exposure to moisture, which, in turn, produces widespread organ toxicity primarily involving the lungs, heart, liver, and kidneys. Cardiac manifestations of AP poisoning include toxic myocarditis, refractory heart failure, bradyarrhythmias, and tachyarrhythmias including ventricular tachycardia (VT). A 19-year-old depressed male farm worker ingested ten 500-mg tablets of Celphos in a suicide attempt. Each Celphos tablet contains 56% AP. Over the course of 10 hours, the patient developed heart failure and respiratory failure associated with a rise in serum troponin level to 12.7 ng/mL. Serum electrolytes (including magnesium) and serum creatinine levels were normal throughout. His course was further complicated by acidemia and hypotension. These hemodynamic and metabolic abnormalities were initially corrected by assisted ventilation and continuous veno-venous hemofiltration. However, he developed hemodynamically stable sustained monomorphic VT, which proved unresponsive to treatment with intravenous magnesium sulfate and intravenous amiodarone therapy. After a decline in blood pressure, 6 attempts at electrocardioversion failed to restore sinus rhythm, and he died. Postmortem histologic examination of myocardium showed contraction band necrosis, early coagulation necrosis, edema, hemorrhage, and pyknosis of cardiac myocyte nuclei. Ventricular tachycardia associated with AP poisoning has been successfully treated with magnesium sulfate, amiodarone, and electrocardioversion. This case report documents failure of all 3 of these therapeutic modalities.

  7. [Magnesium deficiency and therapy in cardiac arrhythmias: recommendations of the German Society for Magnesium Research].

    PubMed

    Vierling, W; Liebscher, D-H; Micke, O; von Ehrlich, B; Kisters, K

    2013-05-01

    Aim of the recommendations of the German Society for Magnesium Research: Recognition and compensation of magnesium deficiency in patients with risk factors for cardiac arrhythmias or manifest rhythm disturbances. Prevention of arrhythmias by administration of magnesium. Therapeutic administration of magnesium in patients with arrhythmias with and without magnesium deficiency. The current state of knowledge claims for considering the status of magnesium and the possibility of a therapeutic intervention with magnesium within the concept of the treatment of cardiovascular diseases. The use of magnesium as single agent or as an adjunct to other therapeutic actions in the prevention and therapy of cardiac arrhythmias can be effective and, in case of oral administration, very safe. In case of parenteral administration, it is important to use adequate doses, monitor cardiovascular and neuromuscular parameters and to consider contraindications.

  8. Substrate and method for the formation of continuous magnesium diboride and doped magnesium diboride wire

    DOEpatents

    Suplinskas, Raymond J.; Finnemore, Douglas; Bud'ko, Serquei; Canfield, Paul

    2007-11-13

    A chemically doped boron coating is applied by chemical vapor deposition to a silicon carbide fiber and the coated fiber then is exposed to magnesium vapor to convert the doped boron to doped magnesium diboride and a resultant superconductor.

  9. Microstructural Effects on the Spall Properties of ECAE Magnesium and Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Williams, Cyril

    2015-06-01

    Magnesium and magnesium alloys are light weight materials and hence, are being increasingly employed as light armor in military applications. However, because of its limited slip systems (HCP) magnesium and magnesium alloys are relatively brittle as compared to FCC and BCC lattice structures. For this study, the effects of microstructure on the spall properties of magnesium and magnesium alloys processed using Equi-Channel Angular Extrusion (ECAE) were investigated using a 51 mm and 105 mm bore gas guns. Symmetric spall and recovery plate impact experiments were performed at impact velocities ranging from approximately 100 m/s and 400 m/s. Free surface velocity profiles of the shocked samples were obtained using Photonic Doppler Velocimetry (PDV). The spall strength and Hugoniot Elastic Limit (HEL) were extracted from the free surface velocity profiles. In addition, the microstructures of the pre-shocked and post-shocked magnesium and magnesium alloys were acquired using Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM).

  10. Combustion Synthesis and Properties of Fine Particle Spinel Manganites

    NASA Astrophysics Data System (ADS)

    Dhas, N. Arul; Patil, K. C.

    1993-02-01

    Fine particle spinel manganites have been prepared by thermal decomposition of the precursors N2H5M1/3Mn2/3(N2H3COO)3 · H2O (M = Co and Ni) and M1/3 Mn2/3(N2H3COO)2 · 2H2O (M = Mg and Zn), as well as by the combustion of redox mixtures containing M(II) nitrate (M = Mg, Co, Ni, Cu, and Zn), Mn(II) nitrate, and maleic hydrazide (MH) in the required molar ratio. Both the precursor and redox mixtures undergo self-propagating, gas-producing, exothermic reactions once ignited at 250-375°C to yield corresponding manganites in less than 5 min. Formation of single phase products was confirmed by X-ray powder diffraction patterns. The manganites are of submicrometer size and have surface area in the range 20-76 m2/g.

  11. On the influence of applied fields on spinel formation

    SciTech Connect

    KORTE,C.; FARER,J.K.; RAVISHANKAR,N.; MICHAEL,JOSEPH R.; SCHMALZRIED,J.; CARTER,C.B.

    2000-04-04

    Interfaces play an important role in determining the effect of electric fields on the mechanism of the formation spinel by solid-state reaction. The reaction occurs by the movement of phase boundaries but the rate of this movement can be affected by grain boundaries in the reactants or in the reaction product. Only by understanding these relationships will it be possible to engineer their behavior. As a particular example of such a study, MgIn{sub 2}O{sub 4} can be formed by the reaction between single-crystal MgO substrate and a thin film of In{sub 2}O{sub 3} with or without an applied electric field. High-resolution backscattered electron (BSE) imaging and electron backscattered diffraction (EBSD) in a scanning electron microscope (SEM) has been used to obtain complementary chemical and crystallographic information.

  12. Lattice-cell orientation disorder in complex spinel oxides

    DOE PAGES

    Chen, Yan; Cheng, Yongqiang; Li, Juchuan; ...

    2016-11-07

    Transition metal (TM) substitution has been widely applied to change complex oxides crystal structures to create high energy density electrodes materials in high performance rechargeable lithium-ion batteries. The complex local structure in the oxides imparted by the TM arrangement often impacts their electrochemical behaviors by influencing the diffusion and intercalation of lithium. Here, a major discrepancy is demonstrated between the global and local structures of the promising high energy density and high voltage LiNi0.5Mn1.5O4 spinel cathode material that contradicts the existing structural models. A new single-phase lattice-cell orientation disorder model is proposed as the mechanism for the local ordering thatmore » explains how the inhomogeneous local distortions and the coherent connection give rise to the global structure in the complex oxide. As a result, the single-phase model is consistent with the electrochemical behavior observation of the materials.« less

  13. Lattice-cell orientation disorder in complex spinel oxides

    SciTech Connect

    Chen, Yan; Cheng, Yongqiang; Li, Juchuan; Feygenson, Mikhail; Heller, William T.; Liang, Chengdu; An, Ke

    2016-11-07

    Transition metal (TM) substitution has been widely applied to change complex oxides crystal structures to create high energy density electrodes materials in high performance rechargeable lithium-ion batteries. The complex local structure in the oxides imparted by the TM arrangement often impacts their electrochemical behaviors by influencing the diffusion and intercalation of lithium. Here, a major discrepancy is demonstrated between the global and local structures of the promising high energy density and high voltage LiNi0.5Mn1.5O4 spinel cathode material that contradicts the existing structural models. A new single-phase lattice-cell orientation disorder model is proposed as the mechanism for the local ordering that explains how the inhomogeneous local distortions and the coherent connection give rise to the global structure in the complex oxide. As a result, the single-phase model is consistent with the electrochemical behavior observation of the materials.

  14. Orbital glass state of the nearly metallic spinel cobalt vanadate

    DOE PAGES

    Koborinai, R.; Dissanayake, Sachith E.; Reehuis, M.; ...

    2016-01-19

    Strain, magnetization, dielectric relaxation, and unpolarized and polarized neutron diffraction measurements were performed to study the magnetic and structural properties of spinel Co1–xV2+xO4. The strain measurement indicates that, upon cooling, ΔL/L in the order of ~10–4 starts increasing below TC, becomes maximum at Tmax, and then decreases and changes its sign at T*. Neutron measurements indicate that a collinear ferrimagnetic order develops below TC and upon further cooling noncollinear ferrimagnetic ordering occurs below Tmax. At low temperatures, the dielectric constant exhibits a frequency dependence, indicating slow dynamics. Lastly, these results indicate the existence of an orbital glassy state at lowmore » temperatures in this nearly metallic frustrated magnet.« less

  15. Orbital glass state of the nearly metallic spinel cobalt vanadate

    SciTech Connect

    Koborinai, R.; Dissanayake, Sachith E.; Reehuis, M.; Matsuda, Masaaki; Kajita, T.; Kuwahara, H.; Lee, Seung -Hun; Katsufuji, T.

    2016-01-19

    Strain, magnetization, dielectric relaxation, and unpolarized and polarized neutron diffraction measurements were performed to study the magnetic and structural properties of spinel Co1–xV2+xO4. The strain measurement indicates that, upon cooling, ΔL/L in the order of ~10–4 starts increasing below TC, becomes maximum at Tmax, and then decreases and changes its sign at T*. Neutron measurements indicate that a collinear ferrimagnetic order develops below TC and upon further cooling noncollinear ferrimagnetic ordering occurs below Tmax. At low temperatures, the dielectric constant exhibits a frequency dependence, indicating slow dynamics. Lastly, these results indicate the existence of an orbital glassy state at low temperatures in this nearly metallic frustrated magnet.

  16. Barred olivine 'chondrules' in lunar spinel troctolite 62295

    NASA Technical Reports Server (NTRS)

    Roedder, E.; Weiblen, P. W.

    1977-01-01

    Several objects have been found in sections of lunar igneous spinel troctolite 62295 that resemble certain meteoritic barred olivine chondrules. Each consists of an apparently spherical single crystal of Fo90 olivine, approximately 0.6-0.8 mm in diameter, containing a set of approximately 30-40 subparallel stringers of An95 plagioclase, whereas the stringers in ordinary meteoritic chondrules consist of glass. The olivine of the 62295 chondrules is also more magnesian, and is radially zoned, having a relatively iron-rich core and rim and an iron-poor intermediate zone. Several possible origins are proposed: impact-generated melt globules solidified in flight, spherical phenocrysts, and meteoritic chondrules, but none of these seems adequate to explain the detailed observations.

  17. Catalysts comprising magnesium and a transition metal

    SciTech Connect

    Bujadoux, K.

    1984-10-09

    A catalyst comprising the product obtained by bringing into contact a compound of magnesium comprising at least one species selected from the group consisting of magnesium monohalides (MgX), halo-magnesium hydrides (HMgX) and magnesium hydride (MgH/sub 2/), X being a halogen and the said species MgX or HMgX being obtained by thermal decomposition of a powdery organo-magnesium halide R/sub 1/MgX wherein R/sub 1/ is an organic radical; and at least one halide of a transistion metal selected from the group consisting of titanium and vanadium, the valency of said metal in said halide being lower than or equal to 3, the quantities being such that the atomic ratio of magnesium to said transistion metal is between 1 and 25, and a catalyst system including the catalyst that is suitable for use in the polymerization of olefins and particularly ethylene.

  18. The development, characterization and testing of magnesium-rich primers

    NASA Astrophysics Data System (ADS)

    Battocchi, Dante

    Aluminum alloys are widely used in aircraft industry for their strength and light weight. Those alloys that are hardened by precipitation, especially the Copper-rich of the 2000 series, are prone to corrosion and are protected against it using chromate containing coatings. The primary component of these coating systems is Chromium 6+ (CrVI) that has been found to be very toxic in the environment and carcinogenic, toxic and mutagenic in humans. The Mg-rich primer development is the result of a successful multi-year project funded by the US Air-force with its objective the replacement of coatings based on CrVI with a class of coatings less toxic and with comparable protective performances. The Mg rich primer fulfilled the USAF requirements and it is currently undergoing commercial and military qualifications testing. The use of Mg as one of the active pigments in coatings allows the primer to protect the underlying Al sacrificially, not considered possible for this substrate until now. Mg is anodic to most of the other structural metals and when particulate Mg became available commercially, the concept of the primer was first developed by analogy to Zn-rich coatings for steel. When Mg and Al are in contact and immersed in a corrosive environment, magnesium corrodes preferentially and protects the aluminum.

  19. Spinel and post-spinel phase assemblages in Zn2TiO4: an experimental and theoretical study

    NASA Astrophysics Data System (ADS)

    Zhang, Yanyao; Liu, Xi; Shieh, Sean R.; Bao, Xinjian; Xie, Tianqi; Wang, Fei; Zhang, Zhigang; Prescher, Clemens; Prakapenka, Vitali B.

    2017-02-01

    Zn2TiO4 spinel (Zn2TiO4-Sp) was synthesized by a solid-state reaction method (1573 K, room P and 72 h) and quasi-hydrostatically compressed to 24 GPa using a DAC coupled with a synchrotron X-ray radiation (ambient T). We found that the Zn2TiO4-Sp was stable up to 21 GPa and transformed to another phase at higher P. With some theoretical simulations, we revealed that this high- P phase adopted the CaTi2O4-type structure (Zn2TiO4-CT). Additionally, the isothermal bulk modulus ( K T) of the Zn2TiO4-Sp was experimentally obtained as 156.0(44) GPa and theoretically obtained as 159.1(4) GPa, with its first pressure derivative K_{{T}}' as 3.8(6) and 4.37(4), respectively. The volumetric and axial isothermal bulk moduli of the Zn2TiO4-CT were theoretically obtained as K T = 150(2) GPa (K_{{T}}' = 5.4(2); for the volume), K T- a = 173(2) GPa (K_{{{T-}}a}' = 3.9(1); for the a-axis), K T- b = 74(2) GPa (K_{{{T-}}b}' = 7.0(2); for the b-axis), and K T- c = 365(8) GPa (K_{{{T-}}c}' = 1.5(4); for the c-axis), indicating a strong elastic anisotropy. The Zn2TiO4-CT was found as 10.0 % denser than the Zn2TiO4-Sp at ambient conditions. The spinel and post-spinel phase assemblages for the Zn2TiO4 composition at high T have been deduced as Zn2TiO4-Sp, ZnTiO3-ilmenite + ZnO-wurtzite, ZnTiO3-ilmenite + ZnO-rock salt, ZnTiO3-perovskite + ZnO-rock salt, and Zn2TiO4-CT as P increases, which presumably implies a potential stability field for a CT-type Mg2SiO4 at very high P.

  20. The distribution of chromium among orthopyroxene, spinel and silicate liquid at atmospheric pressure

    NASA Technical Reports Server (NTRS)

    Barnes, S. J.

    1986-01-01

    The Cr distributions for a synthetic silicate melt equilibrated with bronzitic orthopyroxene and chromite spinel between 1334 and 1151 C over a range of oxygen fugacities between the nickel-nickel oxide and iron-wuestite buffers are studied. The occurrence, chemical composition, and structure of the orthopyroxene-silicate melt and the spinel-silicate melt are described. It is observed that the Cr content between bronzite and the melt increases with falling temperature along a given oxygen buffer and decreases with falling oxygen fugacity at a given temperature; however, the Cr content of the melt in equilibrium with spinel decreases with falling temperature and increases with lower oxygen fugacity.