TUNGSTEN BRONZE RELATED NON-NOBLE ELECTROCATALYSTS.

DTIC Science & Technology

FUEL CELLS, *CATALYSTS), (*OXYGEN, *ELECTRODES), (* SILICIDES , ELECTRODES), (*CARBIDES, ELECTRODES), (*TUNGSTEN COMPOUNDS, *ELECTROCHEMISTRY...CATALYSTS, TITANIUM COMPOUNDS, ZIRCONIUM COMPOUNDS, VANADIUM COMPOUNDS, NIOBIUM COMPOUNDS, TUNGSTEN COMPOUNDS, TANTALUM COMPOUNDS, MOLYBDENUM COMPOUNDS, SULFURIC ACID, CRYSTAL GROWTH, SODIUM COMPOUNDS

Vapor pressure and evaporation rate of certain heat-resistant compounds in a vacuum at high temperatures

NASA Technical Reports Server (NTRS)

Bolgar, A. S.; Verkhoglyadova, T. S.; Samsonov, G. V.

1985-01-01

The vapor pressure and evaporation rate of borides of titanium, zirconium, and chrome; and of strontium and carbides of titanium, zirconium, and chrome, molybdenum silicide; and nitrides of titanium, niobium, and tantalum in a vacuum were studied. It is concluded that all subject compounds evaporate by molecular structures except AlB sub 12' which dissociates, losing the aluminum.

Braze material for joining ceramic to metal and ceramic to ceramic surfaces and joined ceramic to metal and ceramic to ceramic article

DOEpatents

Hunt, T.K.; Novak, R.F.

1991-05-07

An improved active metal braze filler material is provided in which the coefficient of thermal expansion of the braze filler is more closely matched with that of the ceramic and metal, or two ceramics, to provide ceramic to metal, or ceramic to ceramic, sealed joints and articles which can withstand both high temperatures and repeated thermal cycling without failing. The braze filler material comprises a mixture of a material, preferably in the form of a powder, selected from the group consisting of molybdenum, tungsten, silicon carbide and mixtures thereof, and an active metal filler material selected from the group consisting of alloys or mixtures of nickel and titanium, alloys or mixtures of nickel and zirconium, alloys or mixtures of nickel, titanium, and copper, alloys or mixtures of nickel, titanium, and zirconium, alloys or mixtures of niobium and nickel, alloys or mixtures of niobium and zirconium, alloys or mixtures of niobium and titanium, alloys or mixtures of niobium, titanium, and nickel, alloys or mixtures of niobium, zirconium, and nickel, and alloys or mixtures of niobium, titanium, zirconium, and nickel. The powder component is selected such that its coefficient of thermal expansion will effect the overall coefficient of thermal expansion of the braze material so that it more closely matches the coefficients of thermal expansion of the ceramic and metal parts to be joined. 3 figures.

Braze material for joining ceramic to metal and ceramic to ceramic surfaces and joined ceramic to metal and ceramic to ceramic article

DOEpatents

Hunt, Thomas K.; Novak, Robert F.

1991-01-01

An improved active metal braze filler material is provided in which the coefficient of thermal expansion of the braze filler is more closely matched with that of the ceramic and metal, or two ceramics, to provide ceramic to metal, or ceramic to ceramic, sealed joints and articles which can withstand both high temperatures and repeated thermal cycling without failing. The braze filler material comprises a mixture of a material, preferably in the form of a powder, selected from the group consisting of molybdenum, tungsten, silicon carbide and mixtures thereof, and an active metal filler material selected from the group consisting of alloys or mixtures of nickel and titanium, alloys or mixtures of nickel and zirconium, alloys or mixtures of nickel, titanium, and copper, alloys or mixtures of nickel, titanium, and zirconium, alloys or mixtures of niobium and nickel, alloys or mixtures of niobium and zirconium, alloys or mixtures of niobium and titanium, alloys or mixtures of niobium, titanium, and nickel, alloys or mixtures of niobium, zirconium, and nickel, and alloys or mixtures of niobium, titanium, zirconium, and nickel. The powder component is selected such that its coefficient of thermal expansion will effect the overall coefficient of thermal expansion of the braze material so that it more closely matches the coefficients of thermal expansion of the ceramic and metal parts to be joined.

Molybdenum disilicide composites reinforced with zirconia and silicon carbide

DOEpatents

Petrovic, John J.

1995-01-01

Compositions consisting essentially of molybdenum disilicide, silicon carbide, and a zirconium oxide component. The silicon carbide used in the compositions is in whisker or powder form. The zirconium oxide component is pure zirconia or partially stabilized zirconia or fully stabilized zirconia.

Niobium-Matrix-Composite High-Temperature Turbine Blades

NASA Technical Reports Server (NTRS)

Kaplan, Richard B.; Tuffias, Robert H.; La Ferla, Raffaele; Heng, Sangvavann; Harding, John T.

1995-01-01

High-temperture composite-material turbine blades comprising mainly niobium matrices reinforced with refractory-material fibers being developed. Of refractory fibrous materials investigated, FP-AL(2)0(3), tungsten, and polymer-based SiC fibers most promising. Blade of this type hollow and formed in nearly net shape by wrapping mesh of reinforcing refractory fibers around molybdenum mandrel, then using thermal-gradient chemical-vapor infiltration (CVI) to fill interstices with niobium. CVI process controllable and repeatable, and kinetics of both deposition and infiltration well understood.

Molybdenum disilicide composites reinforced with zirconia and silicon carbide

DOEpatents

Petrovic, J.J.

1995-01-17

Compositions are disclosed consisting essentially of molybdenum disilicide, silicon carbide, and a zirconium oxide component. The silicon carbide used in the compositions is in whisker or powder form. The zirconium oxide component is pure zirconia or partially stabilized zirconia or fully stabilized zirconia.

Concept Feasibility Report for Electroplating Zirconium onto Uranium Foil - Year 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coffey, Greg W.; Meinhardt, Kerry D.; Joshi, Vineet V.

2015-03-01

The Fuel Fabrication Capability within the U.S. High Performance Research Reactor Conversion Program is funded through the National Nuclear Security Administration (NNSA) NA-26 (Office of Material Management and Minimization). An investigation was commissioned to determine the feasibility of using electroplating techniques to apply a coating of zirconium onto depleted uranium/molybdenum alloy (U-10Mo). Electroplating would provide an alternative method to the existing process of hot roll-bonding zirconium foil onto the U-10Mo fuel foil during the fabrication of fuel elements for high-performance research reactors. The objective of this research was to develop a reproducible and scalable plating process that will produce amore » uniform, 25 μm thick zirconium metal coating on U-10Mo foil. In previous work, Pacific Northwest National Laboratory (PNNL) established a molten salt electroplating apparatus and protocol to plate zirconium metal onto molybdenum foil (Coffey 2015). During this second year of the research, PNNL furthered this work by moving to the U-10Mo alloy system (90 percent uranium:10 percent molybdenum). The original plating apparatus was disassembled and re-assembled in a laboratory capable of handling low-level radioactive materials. Initially, the work followed the previous year’s approach, and the salt bath composition was targeted at the eutectic composition (LiF:NaF:ZrF4 = 26:37:37 mol%). Early results indicated that the formation of uranium fluoride compounds would be problematic. Other salt bath compositions were investigated in order to eliminate the uranium fluoride production (LiF:NaF = 61:39 mol% and LiF:NaF:KF = 46.5:11.5:42 mol% ). Zirconium metal was used as the crucible for the molten salt. Three plating methods were used—isopotential, galvano static, and pulsed plating. The molten salt method for zirconium metal application provided high-quality plating on molybdenum in PNNL’s previous work. A key advantage of this approach is

Ceramic material suitable for repair of a space vehicle component in a microgravity and vacuum environment, method of making same, and method of repairing a space vehicle component

NASA Technical Reports Server (NTRS)

Riedell, James A. (Inventor); Easler, Timothy E. (Inventor)

2009-01-01

A precursor of a ceramic adhesive suitable for use in a vacuum, thermal, and microgravity environment. The precursor of the ceramic adhesive includes a silicon-based, preceramic polymer and at least one ceramic powder selected from the group consisting of aluminum oxide, aluminum nitride, boron carbide, boron oxide, boron nitride, hafnium boride, hafnium carbide, hafnium oxide, lithium aluminate, molybdenum silicide, niobium carbide, niobium nitride, silicon boride, silicon carbide, silicon oxide, silicon nitride, tin oxide, tantalum boride, tantalum carbide, tantalum oxide, tantalum nitride, titanium boride, titanium carbide, titanium oxide, titanium nitride, yttrium oxide, zirconium diboride, zirconium carbide, zirconium oxide, and zirconium silicate. Methods of forming the ceramic adhesive and of repairing a substrate in a vacuum and microgravity environment are also disclosed, as is a substrate repaired with the ceramic adhesive.

Methods of repairing a substrate

NASA Technical Reports Server (NTRS)

Riedell, James A. (Inventor); Easler, Timothy E. (Inventor)

2011-01-01

A precursor of a ceramic adhesive suitable for use in a vacuum, thermal, and microgravity environment. The precursor of the ceramic adhesive includes a silicon-based, preceramic polymer and at least one ceramic powder selected from the group consisting of aluminum oxide, aluminum nitride, boron carbide, boron oxide, boron nitride, hafnium boride, hafnium carbide, hafnium oxide, lithium aluminate, molybdenum silicide, niobium carbide, niobium nitride, silicon boride, silicon carbide, silicon oxide, silicon nitride, tin oxide, tantalum boride, tantalum carbide, tantalum oxide, tantalum nitride, titanium boride, titanium carbide, titanium oxide, titanium nitride, yttrium oxide, zirconium boride, zirconium carbide, zirconium oxide, and zirconium silicate. Methods of forming the ceramic adhesive and of repairing a substrate in a vacuum and microgravity environment are also disclosed, as is a substrate repaired with the ceramic adhesive.

40 CFR 721.10602 - Lead niobium titanium zirconium oxide.

Code of Federal Regulations, 2013 CFR

2013-07-01

... as specified in § 721.90 (a)(4), (b)(4), and (c)(4) (Where N=8, and 8 is an aggregate of releases for the following substances: Lead strontium titanium zirconium oxide (PMN P-11-270; CAS No. 61461-40-3... strontium titanium tungsten oxide (PMN P-11-272; CAS No. 1262279-30-0); Lanthanum lead titanium zirconium...

40 CFR 721.10602 - Lead niobium titanium zirconium oxide.

Code of Federal Regulations, 2014 CFR

2014-07-01

... as specified in § 721.90 (a)(4), (b)(4), and (c)(4) (Where N=8, and 8 is an aggregate of releases for the following substances: Lead strontium titanium zirconium oxide (PMN P-11-270; CAS No. 61461-40-3... strontium titanium tungsten oxide (PMN P-11-272; CAS No. 1262279-30-0); Lanthanum lead titanium zirconium...

Ferrous Analysis.

ERIC Educational Resources Information Center

Straub, William A.

1989-01-01

Elements covered in this review include: aluminum, antimony, arsenic, bismuth, boron, calcium, carbon, chromium, cobalt, copper, hydrogen, iron, lead, magnesium, manganese, molybdenum, nickel, niobium, nitrogen, oxygen, phosphorus, platinum, rare earths, silicons, sulfur, tin, titanium, tungsten, vanadium, zinc, and zirconium. Analytical methods…

Tensile Properties of Molybdenum and Tungsten from 2500 to 3700 F

NASA Technical Reports Server (NTRS)

Hall, Robert W.; Sikora, Paul F.

1959-01-01

Specimens of commercially pure sintered tungsten, arc-cast unalloyed molybdenum, and two arc-cast molybdenum-base alloys (one with 0.5 percent titanium, the other with 0.46 percent titanium and 0.07 percent zirconium) were fabricated from 1/2-inch-diameter rolled or swaged bars. All specimens were evaluated in short-time tensile tests in the as-received condition, and all except the molybdenum-titanium-zirconium alloy were tested after a 30-minute recrystallization anneal at 3800 F in a vacuum of approximately 0.1 micron. Results showed that the tungsten was considerably stronger than either the arc-cast unalloyed molybdenum or the molybdenum-base alloys over the 2500 to 3700 F temperature range. Recrystallization of swaged tungsten at 3800 F considerably reduced its tensile strength at 2500 F. However, above 3100 F, the as-swaged tungsten specimens recrystallized during testing, and had about the same strength as when recrystallized at 3800 F before evaluation. The ductility of molybdenum-base materials was very high at all test temperatures; the ductility of tungsten decreased sharply above about 3120 F.

As-cast uranium-molybdenum based metallic fuel candidates and the effects of carbon addition

NASA Astrophysics Data System (ADS)

Blackwood, Van Stephen

The objective of this research was to develop and recommend a metallic nuclear fuel candidate that lowered the onset temperature of gamma phase formation comparable or better than the uranium-10 wt. pct. molybdenum alloy, offered a solidus temperature as high or higher than uranium-10 wt. pct. zirconium (1250°C), and stabilized the fuel phase against interaction with iron and steel at least as much as uranium-10 wt. pct. zirconium stabilized the fuel phase. Two new as-cast alloy compositions were characterized to assess thermal equilibrium boundaries of the gamma phase field and the effect of carbon addition up to 0.22 wt. pct. The first system investigated was uranium- x wt. pct. M where x ranged between 5-20 wt. pct. M was held at a constant ratio of 50 wt. pct. molybdenum, 43 wt. pct. titanium, and 7 wt. pct. zirconium. The second system investigated was the uranium-molybdenum-tungsten system in the range 90 wt. pct. uranium - 10 wt. pct. molybdenum - 0 wt. pct. tungsten to 80 wt. pct. uranium - 10 wt. pct. molybdenum - 10 wt. pct. tungsten. The results showed that the solidus temperature increased with increased addition of M up to 12.5 wt. pct. for the uranium-M system. Alloy additions of titanium and zirconium were removed from uranium-molybdenum solid solution by carbide formation and segregation. The uranium-molybdenum-tungsten system solidus temperature increased to 1218°C at 2.5 wt. pct. with no significant change in temperature up to 5 wt. pct. tungsten suggesting the solubility limit of tungsten had been reached. Carbides were observed with surrounding areas enriched in both molybdenum and tungsten. The peak solidus temperatures for the alloy systems were roughly the same at 1226°C for the uranium-M system and 1218°C for the uranium-molybdenum-tungsten system. The uranium-molybdenum-tungsten system required less alloy addition to achieve similar solidus temperatures as the uranium-M system.

SEPARATION OF POLONIUM, PROTACTINIUM OR MIXTURES THEREOF IN AQUEOUS SOLUTION FROM BISMUTH, LEAD, ZIRCONIUM AND/OR COLUMBIUM VALUES

DOEpatents

Van Winkle, Q.; Kraus, K.A.

1959-10-27

A process is presented for separating polonium, protactinium, or mixtures thereof in aqueous solution from bismuth, zirconium, lead, and niobium values contained in the solution. The method comprises providing hydrochloric acid in the solution in a concentration of at least 5N. contacting the aqueous solution with a substantially waterimmiscible organic solvent such as diisopropyl ketone, and separating the aqueous phase containing the bismuth, zirconium, lead, and niobium from the organic extract phase containing the polonium, protactinium, or mixture thereof.

Standard methods for chemical analysis of steel, cast iron, open-hearth iron, and wrought iron

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1973-01-01

Methods are described for determining manganese, phosphorus, sulfur, selenium, copper, nickel, chromium, vanadium, tungsten, titanium, lead, boron, molybdenum ( alpha -benzoin oxime method), zirconium (cupferron --phosphate method), niobium and tantalum (hydrolysis with perchloric and sulfurous acids (gravimetric, titrimetric, and photometric methods)), and beryllium (oxide method). (DHM)

Field determination of microgram quantities of niobium in rocks

USGS Publications Warehouse

Ward, F.N.; Marranzino, A.P.

1955-01-01

A rapid, simple, and moderately accurate method was needed for the determination of traces of niobium in rocks. The method developed is based on the reaction of niobium(V) with thiocyanate ion in a 4M hydrochloric acid and 0.5M tartaric acid medium, after which the complex is extracted with ethyl ether. The proposed procedure is applicable to rocks containing from 50 to 2000 p.p.m. of niobium, and, with modifications, can be used on rocks containing larger amounts. Five determinations on two rocks containing 100 p.p.m. or less of niobium agree within 5 p.p.m. of the mean, and the confidence limits at the 95% level are, respectively, ??6 and ??4 p.p.m. The addition of acetone to the ether extract of the niobium thiocyanate inhibits the polymerization of the thiocyanate ion and stabilizes the solution for at least 20 hours. The proposed procedure permits the determination of 20 ?? of niobium in the presence of 1000 ?? of iron, titanium, or uranium; 500 ?? of vanadium; or 100 ?? of tungsten or molybdenum or both.

Electrical insulator assembly with oxygen permeation barrier

DOEpatents

Van Der Beck, R.R.; Bond, J.A.

1994-03-29

A high-voltage electrical insulator for electrically insulating a thermoelectric module in a spacecraft from a niobium-1% zirconium alloy wall of a heat exchanger filled with liquid lithium while providing good thermal conductivity between the heat exchanger and the thermoelectric module. The insulator has a single crystal alumina layer (SxAl[sub 2]O[sub 3], sapphire) with a niobium foil layer bonded thereto on the surface of the alumina crystal facing the heat exchanger wall, and a molybdenum layer bonded to the niobium layer to act as an oxygen permeation barrier to preclude the oxygen depleting effects of the lithium from causing undesirable niobium-aluminum intermetallic layers near the alumina-niobium interface. 3 figures.

Semimicrodetermination of tantalum with selenous acid

USGS Publications Warehouse

Grimaldi, F.S.; Schnepfe, M.M.

1958-01-01

Tantalum is separated and determined gravimetrically by precipitation with selenous acid from a highly acidic solution containing oxalic and tartaric acids. The method is selective for the determination of up to 30 mg. of tantalum pentoxide, and tolerates relatively large amounts of scandium, yttrium, cerium, titanium, zirconium, thorium, vanadium, niobium, molybdenum, tungsten, uranium, iron, aluminum, gallium, tin, lead, antimony, and bismuth. The separation of tantalum from niobium and titanium is not strictly quantitative, and correction is made colorimetrically for the small amounts of niobium and titanium co-precipitating with the tantalum. The method was applied to the determination of tantalum in tantaloniobate ores.

BRAZE BONDING OF COLUMBIUM

DOEpatents

Heestand, R.L.; Picklesimer, M.L.

1962-07-31

A method of brazing niobium parts together is described. The surfaces of the parts to be brazed together are placed in abutting relationship with a brazing alloy disposed adjacent. The alloy consists essentially of, by weight, 12 to 25% niobium, 0.5 to 5% molybdenum, and the balance zirconium, The alloy is heated to at least its melting point to braze the parts together. The brazed joint is then cooled. The heating, melting and cooling take place in an inert atmosphere. (AEC)

URANIUM ALLOYS

DOEpatents

Seybolt, A.U.

1958-04-15

Uranium alloys containing from 0.1 to 10% by weight, but preferably at least 5%, of either zirconium, niobium, or molybdenum exhibit highly desirable nuclear and structural properties which may be improved by heating the alloy to about 900 d C for an extended period of time and then rapidly quenching it.

Electrical insulator assembly with oxygen permeation barrier

DOEpatents

Van Der Beck, Roland R.; Bond, James A.

1994-01-01

A high-voltage electrical insulator (21) for electrically insulating a thermoelectric module (17) in a spacecraft from a niobium-1% zirconium alloy wall (11) of a heat exchanger (13) filled with liquid lithium (16) while providing good thermal conductivity between the heat exchanger and the thermoelectric module. The insulator (21) has a single crystal alumina layer (SxAl.sub.2 O.sub.3, sapphire) with a niobium foil layer (32) bonded thereto on the surface of the alumina crystal (26) facing the heat exchanger wall (11), and a molybdenum layer (31) bonded to the niobium layer (32) to act as an oxygen permeation barrier to preclude the oxygen depleting effects of the lithium from causing undesirable niobium-aluminum intermetallic layers near the alumina-niobium interface.

Zirconia-molybdenum disilicide composites

DOEpatents

Petrovic, John J.; Honnell, Richard E.

1991-01-01

Compositions of matter comprised of molybdenum disilicide and zirconium oxide in one of three forms: pure, partially stabilized, or fully stabilized and methods of making the compositions. The stabilized zirconia is crystallographically stabilized by mixing it with yttrium oxide, calcium oxide, cerium oxide, or magnesium oxide and it may be partially stabilized or fully stabilized depending on the amount of stabilizing agent in the mixture.

Characterization of weld metal microstructure in a Ni-30Cr alloy with additions of niobium and molybdenum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wheeling, Rebecca A., E-mail: wheeling.8@osu.edu; Lippold, John C., E-mail: lippold.1@osu.edu

2016-05-15

Additions of niobium (Nb) and molybdenum (Mo) were made to an Alloy 690 base alloy in order to investigate the formation of a eutectic constituent at the end of solidification and to evaluate the effect of the eutectic liquid on backfilling (or healing) of solidification cracks. Solidification cracking was induced using the cast pin tear test (CPTT) and regions of backfilling were located and characterized via optical and electron microscopy. Computational predictions of fraction eutectic and composition of the eutectic constituent were compared to experimental findings and were found to correlate well in both cases. The extent of crack backfillingmore » increased significantly with increasing Nb content, but the addition of Mo did not seem to influence the amount of eutectic constituent or the degree of backfilling. SEM/EDS analysis confirmed that the eutectic composition is constant and that increasing Nb above 4 wt% has little effect on expanding the solidification temperature range, but has a beneficial effect on mitigating solidification cracking by a crack healing effect. - Highlights: • Increasing fraction eutectic as a function of Nb, as predicted by ThermoCalc™, is consistent with image analysis results. • Nb, unlike Mo, had a significant effect on the fraction eutectic formed. • Both influence the composition of the eutectic. • Thermocalc™ predictions regarding Nb content in eutectic are consistent with EDS results, but are high for the Mo content. • Increased levels of niobium resulted in a higher degree of crack backfilling and leads to a lower cracking susceptibility. • Mo may influence the eutectic liquid along solidification grain boundaries, improving backfill and thus cracking resistance.« less

Precipitation of molybdenum(V) as the hydroxide and its separation from rhenium.

PubMed

Yatirajam, V; Ahuja, U; Kakkar, L R

1975-03-01

A study of the conditions for precipitation of molybdenum(V) hydroxide shows that for Mo concentration 1 mg ml about 97.5% of the Mo can be precipitated between pH 5 and 5.8. Lower concentrations of molybdenum(V) or molybdenum(VI) can be precipitated quantitatively by using 20 times the amount of zirconium as collector, at the same pH. On this basis, a simple method is given for quantitative separation of rhenium from large amounts of molybdenum and is attested by analysis of synthetic and molybdenite samples.

Amorphous metal alloy

DOEpatents

Wang, R.; Merz, M.D.

1980-04-09

Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

Amorphous metal alloy and composite

DOEpatents

Wang, Rong; Merz, Martin D.

1985-01-01

Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

ON THE GEOCHEMISTRY OF NIOBIUM AND TANTALUM IN CLAYS (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pachadzhanov, D.N.

1963-10-01

With the aid of the spectral method with a preliminary enrichment in tannin, the niobium and tantalum content was determined in some humid and arid clays of the Russian platform. The investigated samples were composed of 354 specimens. The average content of niobium in humid clays is 0.0020%, of tantalum 0.00024% (the Nb/Ta ratio is 8.4) and in arid clays is respectively the content of niobium 0.00133% and the content of tantalum 0.00009% (the Nb/Ta ratio is 14.8). The average value of the content of niobium content for all studied clays is 0.00183% and of the tantalum content 0.00020%, themore » Nb/Ta ratio being 9.1. In clays an interconnection of niobium with tantalum, as well as with aluminium, titanium, zirconium, and hafnium was observed. However, on the background of this connection some separation of the named elements is noted. A tendency for the Nb/Ta ratio shift from the region of matter removal towards the center of the marine basin was observed. The study of niobium and tantalum distribution over different clay fractions showed that one part of elements is connected with zircon and titanium minerals in aleuosand fraction (0.1-- 0.01 mm). Another, approximately similar part is contained in the proper clay fraction (<0. 01 mm), the tantalum somewhat more concentrating in the aleurosand fraction and niobium in the clay fraction. (P.C.H.)« less

About structural phase state of coating based on zirconium oxide formed by microplasma oxidation method

NASA Astrophysics Data System (ADS)

Gubaidulina, Tatiana A.; Sergeev, Viktor P.; Kuzmin, Oleg S.; Fedorischeva, Marina V.; Kalashnikov, Mark P.

2017-12-01

The oxide-ceramic coating based of zirconium oxide is formed by the method of microplasma oxidation. The producing modes of the oxide layers on E110 zirconium alloy are under testing. It was found that using microplasma treatment of E110 zirconium in aluminosilicate electrolyte makes possible the formation of porous oxide-ceramic coatings based on zirconium alloyed by aluminum and niobium. The study is focused on the modes how to form heat-shielding coatings with controlled porosity and minimal amount of microcracks. The structural-phase state of the coating is studied by X-ray diffraction analysis and scanning electron microscopy (SEM). It was found that the ratio of the monoclinic and tetragonal phases changes with the change occurring in the coating formation modes.

Acidic ammonothermal growth of gallium nitride in a liner-free molybdenum alloy autoclave

NASA Astrophysics Data System (ADS)

Malkowski, Thomas F.; Pimputkar, Siddha; Speck, James S.; DenBaars, Steven P.; Nakamura, Shuji

2016-12-01

This paper discusses promising materials for use as internal, non-load bearing components as well as molybdenum-based alloys for autoclave structural components for an ammonothermal autoclave. An autoclave was constructed from the commercial titanium-zirconium-molybdenum (TZM) alloy and was found to be chemically inert and mechanically stable under acidic ammonothermal conditions. Preliminary seeded growth of GaN was demonstrated with negligible incorporation of transition metals (including molybdenum) into the grown material (<1017 cm-3). Molybdenum and TZM were exposed to a basic ammonothermal environment, leading to slight degradation through formation of molybdenum nitride powders on their surface at elevated temperatures (T>560 °C). The possibility of a 'universal', inexpensive, liner-free ammonothermal autoclave capable of exposure to basic and acidic chemistry is demonstrated.

Protected Nuclear Fuel Element

DOEpatents

Kittel, J. H.; Schumar, J. F.

1962-12-01

A stainless steel-clad actinide metal fuel rod for use in fast reactors is reported. In order to prevert cladding failures due to alloy formation between the actinide metal and the stainless steel, a mesh-like sleeve of expanded metal is interposed between them, the sleeve metal being of niobium, tantalum, molybdenum, tungsten, zirconium, or vanadium. Liquid alkali metal is added as a heat transfer agent. (AEC)

DEVELOPMENT OF NIOBIUM-BASE ALLOYS. Period covered January 1, 1956 to March 1, 1957

DOE Office of Scientific and Technical Information (OSTI.GOV)

Begley, R.T. ed.

1957-11-01

The flow and fracture characteristics of commercial purity powder metallurgy niobium were investigated in the range 250 to --196 deg C. Niobium was found to undergo a ductile-brittle transition in the range --125 to --196 deg C, and the transition temperature range of niobium was found to be less affected by the presence of interstitial impurities than many other body-centered cubic metals. The creeprupture properties of powder metallurgy niobium were investigated at 982 and 1O93 deg C (1800 and 2OOO deg F), and the 100-hour rupture strength of commercial niobium in vacuum was determined to be sigdicantiy greater than unalloyedmore » molybdenum. The creep-rupture results suggest that small quantities of gaseous contaminants may be responslble for the high strength of commercial niobium at elevated temperatures. The oxidation behavior of nioblum was investigated in the temperature range 350 to 7OO C. At the higher temperatures, oxidation followed a linear rate law. Between 500 and 625 deg C, the rate of oxidation was found to be nearly independent of temperature. Oxygen and nitrogen contamination of welding atmospheres was studied to determine its effect on the weld properties of niobium. Nitrogen was establlshed to be very detrimental to the mechanical properties of niobium welds. High-purity niobium, having a hardness of less than 60 VPN, was produced by cage-zone refinieg techniques. (auth)« less

A review of refractory materials for vapor-anode AMTEC cells

NASA Astrophysics Data System (ADS)

King, Jeffrey C.; El-Genk, M. S.

2000-01-01

Recently, refractory alloys have been considered as structural materials for vapor-anode Alkali Metal Thermal-to-Electric Conversion (AMTEC) cells, for extended (7-15 years) space missions. This paper reviewed the existing database for refractory metals and alloys of potential use as structural materials for vapor-anode sodium AMTEC cells. In addition to requiring that the vapor pressure of the material be below 10-9 torr (133 nPa) at a typical hot side temperature of 1200 K, other screening considerations were: (a) low thermal conductivity, low thermal radiation emissivity, and low linear thermal expansion coefficient; (b) low ductile-to-brittle transition temperature, high yield and rupture strengths and high strength-to-density ratio; and (c) good compatibility with the sodium AMTEC operating environment, including high corrosion resistance to sodium in both the liquid and vapor phases. Nb-1Zr (niobium-1% zirconium) alloy is recommended for the hot end structures of the cell. The niobium alloy C-103, which contains the oxygen gettering elements zirconium and hafnium as well as titanium, is recommended for the colder cell structure. This alloy is stronger and less thermally conductive than Nb-1Zr, and its use in the cell wall reduces parasitic heat losses by conduction to the condenser. The molybdenum alloy Mo-44.5Re (molybdenum-44.5% rhenium) is also recommended as a possible alternative for both structures if known problems with oxygen pick up and embrittlement of the niobium alloys proves to be intractable. .

Recovery of germanium-68 from irradiated targets

DOEpatents

Phillips, Dennis R.; Jamriska, Sr., David J.; Hamilton, Virginia T.

1993-01-01

A process for selective separation of germanium-68 from proton irradiated molybdenum targets is provided and includes dissolving the molybdenum target in a hydrogen peroxide solution to form a first ion-containing solution, contacting the first ion-containing solution with a cationic resin whereby ions selected from the group consisting of molybdenum, niobium, technetium, selenium, vanadium, arsenic, germanium, zirconium and rubidium remain in a second ion-containing solution while ions selected from the group consisting of rubidium, zinc, beryllium, cobalt, iron, manganese, chromium, strontium, yttrium and zirconium are selectively adsorbed by the first resin, adjusting the pH of the second ion-containing solution to within a range of from about 0.7 to about 3.0, adjusting the soluble metal halide concentration in the second ion-containing solution to a level adapted for subsequent separation of germanium, contacting the pH-adjusted, soluble metal halide-containing second ion-containing solution with a dextran-based material whereby germanium ions are separated by the dextran-based material, and recovering the germanium from the dextran-based material, preferably by distillation.

High quality transparent conducting oxide thin films

DOEpatents

Gessert, Timothy A.; Duenow, Joel N.; Barnes, Teresa; Coutts, Timothy J.

2012-08-28

A transparent conducting oxide (TCO) film comprising: a TCO layer, and dopants selected from the elements consisting of Vanadium, Molybdenum, Tantalum, Niobium, Antimony, Titanium, Zirconium, and Hafnium, wherein the elements are n-type dopants; and wherein the transparent conducting oxide is characterized by an improved electron mobility of about 42 cm.sup.2/V-sec while simultaneously maintaining a high carrier density of .about.4.4e.times.10.sup.20 cm.sup.-3.

Process for recovering niobium from uranium-niobium alloys

DOEpatents

Wallace, Steven A.; Creech, Edward T.; Northcutt, Walter G.

1983-01-01

Niobium is recovered from scrap uranium-niobium alloy by melting the scrap with tin, solidifying the billet thus formed, heating the billet to combine niobium with tin therein, placing the billet in hydrochloric acid to dissolve the uranium and leave an insoluble residue of niobium stannide, then separating the niobium stannide from the acid.

Compatibility of refractory materials for nuclear reactor poison control systems

NASA Technical Reports Server (NTRS)

Sinclair, J. H.

1974-01-01

Metal-clad poison rods have been considered for the control system of an advanced space power reactor concept studied at the NASA Lewis Research Center. Such control rods may be required to operate at temperatures of about 140O C. Selected poison materials (including boron carbide and the diborides of zirconium, hafnium, and tantalum) were subjected to 1000-hour screening tests in contact with candidate refractory metal cladding materials (including tungsten and alloys of tantalum, niobium, and molybdenum) to assess the compatibility of these materials combinations at the temperatures of interest. Zirconium and hafnium diborides were compatible with refractory metals at 1400 C, but boron carbide and tantalum diboride reacted with the refractory metals at this temperature. Zirconium diboride also showed promise as a reaction barrier between boron carbide and tungsten.

Process for recovering niobium from uranium-niobium alloys

DOEpatents

Wallace, S.A.; Creech, E.T.; Northcutt, W.G.

1982-09-27

Niobium is recovered from scrap uranium-niobium alloy by melting the scrap with tin, solidifying the billet thus formed, heating the billet to combine niobium with tin therein, placing the billet in hydrochloric acid to dissolve the uranium and form a precipitate of niobium stannide, then separating the precipitate from the acid.

Physicochemical and mechanical properties of zirconium oxide and niobium oxide modified Portland cement-based experimental endodontic sealers.

PubMed

Viapiana, R; Flumignan, D L; Guerreiro-Tanomaru, J M; Camilleri, J; Tanomaru-Filho, M

2014-05-01

To evaluate the physicochemical and mechanical properties of Portland cement-based experimental sealers (ES) with different radiopacifying agents (zirconium oxide and niobium oxide micro- and nanoparticles) in comparison with the following conventional sealers: AH Plus, MTA Fillapex and Sealapex. The materials were tested for setting time, compressive strength, flow, film thickness, radiopacity, solubility, dimensional stability and formaldehyde release. Data were subjected to anova and Tukey tests (P < 0.05). MTA Fillapex had the shortest setting time and lowest compressive strength values (P < 0.05) compared with the other materials. The ES had flow values similar to the conventional materials, but higher film thickness (P < 0.05) and lower radiopacity (P < 0.05). Similarly to AH Plus, the ES were associated with dimensional expansion (P > 0.05) and lower solubility when compared with MTA Fillapex and Sealapex (P < 0.05). None of the endodontic sealers evaluated released formaldehyde after mixing. With the exception of radiopacity, the Portland cement-based experimental endodontic sealers presented physicochemical properties according to the specifications no 57 ANSI/ADA (ADA Professional Product Review, 2008) and ISO 6876 (Dentistry - Root Canal Sealing Materials, 2012, British Standards Institution, London, UK). The sealers had setting times and flow ability that was adequate for clinical use, satisfactory compressive strength and low solubility. Additional studies should be carried out with the purpose of decreasing the film thickness and to determine the ideal ratio of radiopacifying agents in Portland cement-based root canal sealers. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Investigation of welding and brazing of molybdenum and TZM alloy tubes

NASA Technical Reports Server (NTRS)

Lundblad, Wayne E.

1991-01-01

This effort involved investigating the welding and brazing techniques of molybdenum tubes to be used as cartridges in the crystal growth cartridge. Information is given in the form of charts and photomicrographs. It was found that the recrystallization temperature of molybdenum can be increased by alloying it with 0.5 percent titanium and 0.1 percent zirconium. Recrystallization temperatures for this alloy, known as TZM, become significant around 2500 F. A series of microhardness tests were run on samples of virgin and heat soaked TZM. The test results are given in tabular form. It was concluded that powder metallurgy TZM may be an acceptable cartridge material.

Process for strontium-82 separation

DOEpatents

Heaton, Richard C.; Jamriska, Sr., David J.; Taylor, Wayne A.

1992-01-01

A process for selective separation of strontium-82 and strontium-85 from proton irradiated molybdenum targets comprises dissolving the molybdenum target in a hydrogen peroxide solution to form a first solution containing ions selected from a group consisting of molybdenum, niobium, technetium, selenium, vanadium, arsenic, germanium, zirconium, rubidium, zinc, beryllium, cobalt, iron, manganese, chromium, strontium, and yttrium; passing the solution through a first cationic resin whereby ions selected from a group consisting of zinc, beryllium, cobalt, iron, manganese, chromium, strontium, yttrium a portion of zirconium and a portion of rubidium are selectively absorbed by the first resin; contacting the first resin with an acid solution to strip and remove the absorbed ions from the first cationic exchange resin to form a second solution; evaporating the second solution for a time sufficient to remove substantially all of the acid and water from the solution whereby a residue remains; dissolving the residue in a dilute acid to form a third solution; passing the third solution through a second cationic resin whereby the ions are absorbed by the second resin; contacting the second resin with a dilute sulfuric acid solution whereby the absorbed ions selected from the group consisting of rubidium, zinc, beryllium, cobalt, iron, manganese, chromium and zirconium are selectively removed from the second resin; and contacting the second resin with a dilute acid solution whereby the absorbed strontium ions are selectively removed.

METHOD OF DISSOLVING REFRACTORY ALLOYS

DOEpatents

Helton, D.M.; Savolainen, J.K.

1963-04-23

This patent relates to the dissolution of alloys of uranium with zirconium, thorium, molybdenum, or niobium. The alloy is contacted with an anhydrous solution of mercuric chloride in a low-molecular-weight monohydric alcohol to produce a mercury-containing alcohol slurry. The slurry is then converted to an aqueous system by adding water and driving off the alcohol. The resulting aqueous slurry is electrolyzed in the presence of a mercury cathode to remove the mercury and produce a uranium-bearing aqueous solution. This process is useful for dissolving irradiated nuclear reactor fuels for radiochemical reprocessing by solvent extraction. In addition, zirconium-alloy cladding is selectively removed from uranium dioxide fuel compacts by this means. (AEC)

Metal alloy coatings and methods for applying

DOEpatents

Merz, Martin D.; Knoll, Robert W.

1991-01-01

A method of coating a substrate comprises plasma spraying a prealloyed feed powder onto a substrate, where the prealloyed feed powder comprises a significant amount of an alloy of stainless steel and at least one refractory element selected from the group consisting of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The plasma spraying of such a feed powder is conducted in an oxygen containing atmosphere and forms an adherent, corrosion resistant, and substantially homogenous metallic refractory alloy coating on the substrate.

Peralkaline and peraluminous granites and related mineral deposits of the Arabian Shield, Kingdom of Saudi Arabia

USGS Publications Warehouse

Elliott, James E.

1983-01-01

Existing geochemical and geologic data for many parts of the Arabian Shield were compiled as a basis for evaluating the resource potential of the granites of the Shield. Commodities associated with granites that have potential for economic mineral deposits include tin, tungsten, molybdenum, beryllium, niobium, tantalum, zirconium, uranium, thorium, rare-earth elements, and fluorite. Prospecting methods useful in discriminating those granites having significant economic potential include reconnaissance geologic mapping, petrographic and mineralogic studies, geochemical sampling of rock and wadi sediment, and radiometric surveying.

Oxygen Interaction With Space-Power Materials

NASA Technical Reports Server (NTRS)

Eck, Thomas G.; Hoffman, Richard W.

1996-01-01

Four investigations were undertaken during the period of this grant: (1 ) oxidation of molybdenum and of niobium-1 % zirconium, (2) preparation of and examination of EOIM-3 samples, (3) sputtering of Teflon by oxygen ion bombardment,and (4) sputtering of Ions from copper and aluminum by oxygen and argon ion bombardment. Investigations (1), (3), and (4) used a low-energy Ion gun to bombard surfaces within an ultra-high vacuum system. Particles ejected from the surfaces were detected by a mass spectrometer.

Passivated niobium cavities

DOEpatents

Myneni, Ganapati Rao [Yorktown, VA; Hjorvarsson, Bjorgvin [Lagga Arby, SE; Ciovati, Gianluigi [Newport News, VA

2006-12-19

A niobium cavity exhibiting high quality factors at high gradients is provided by treating a niobium cavity through a process comprising: 1) removing surface oxides by plasma etching or a similar process; 2) removing hydrogen or other gases absorbed in the bulk niobium by high temperature treatment of the cavity under ultra high vacuum to achieve hydrogen outgassing; and 3) assuring the long term chemical stability of the niobium cavity by applying a passivating layer of a superconducting material having a superconducting transition temperature higher than niobium thereby reducing losses from electron (cooper pair) scattering in the near surface region of the interior of the niobium cavity. According to a preferred embodiment, the passivating layer comprises niobium nitride (NbN) applied by reactive sputtering.

Process for strontium-82 separation

DOEpatents

Heaton, R.C.; Jamriska, D.J. Sr.; Taylor, W.A.

1992-12-01

A process for selective separation of strontium-82 and strontium-85 from proton irradiated molybdenum targets comprises dissolving the molybdenum target in a hydrogen peroxide solution to form a first solution containing ions selected from a group consisting of molybdenum, niobium, technetium, selenium, vanadium, arsenic, germanium, zirconium, rubidium, zinc, beryllium, cobalt, iron, manganese, chromium, strontium, and yttrium; passing the solution through a first cationic resin whereby ions selected from a group consisting of zinc, beryllium, cobalt, iron, manganese, chromium, strontium, yttrium a portion of zirconium and a portion of rubidium are selectively absorbed by the first resin; contacting the first resin with an acid solution to strip and remove the absorbed ions from the first cationic exchange resin to form a second solution; evaporating the second solution for a time sufficient to remove substantially all of the acid and water from the solution whereby a residue remains; dissolving the residue in a dilute acid to form a third solution; passing the third solution through a second cationic resin whereby the ions are absorbed by the second resin; contacting the second resin with a dilute sulfuric acid solution whereby the absorbed ions selected from the group consisting of rubidium, zinc, beryllium, cobalt, iron, manganese, chromium and zirconium are selectively removed from the second resin; and contacting the second resin with a dilute acid solution whereby the absorbed strontium ions are selectively removed. 1 fig.

PROCESS OF MAKING SHAPED FUEL FOR NUCLEAR REACTORS

DOEpatents

O'Leary, W.J.; Fisher, E.A.

1964-02-11

A process for making uranium dioxide fuel of great strength, density, and thermal conductivity by mixing it with 0.1 to 1% of a densifier oxide (tin, aluminum, zirconium, ferric, zinc, chromium, molybdenum, titanium, or niobium oxide) and with a plasticizer (0.5 to 3% of bentonite and 0.05 to 2% of methylcellulose, propylene glycol alginate, or ammonium alginate), compacting the mixture obtained, and sintering the bodies in an atmosphere of carbon monoxide or carbon dioxide, with or without hydrogen, or of a nitrogen-hydrogen mixture is described. (AEC)

Developing the Molybdenum Isotopic Proxy in Marine Barite

NASA Astrophysics Data System (ADS)

Erhardt, A. M.; Paytan, A.; Aggarwal, J.

2006-12-01

Molybdenum isotope ratios in seawater fluctuate in response to changing redox conditions and can provide clues into the degree of global ocean anoxia. The isotopic ratio of molybdenum has been shown to be sensitive to the relative proportion of oxic, suboxic, and euxinic environments. Deposition in oxic environments is isotopically light (~ -1.6‰ for δ^{97/95}Mo) relative to an average crustal source (0‰). Conversely, euxinic environments have been shown to be consistently heavier (~1.3‰) than the oxic sink through time, with suboxic sediments falling between these two signals. Shifts in the relative proportion of each sink, relative to a constant source, would alter the isotopic ratio of seawater over long time scales. Previously, this seawater value, and hence the degree of global anoxia, could only be inferred through mass balance calculations. We seek to quantify the isotopic signature of seawater though time using a phase that directly records this ratio. Marine barite precipitates inorganically in the water column directly from seawater, potentially providing a direct record of seawater characteristics. Molybdenum is a trace constituent of barite, with the molybdate ion substituting for sulfate at concentrations of about 1 ppm. To accurately determine the molybdenum isotopic ratio at these low concentrations (<15 ng per sample), modifications to existing measurement techniques are required. We will present the variations made to existing separation and mass-spectrometry techniques and the calibration of these new methods. The modifications were undertaken to reduce molybdenum blank to below 1 ng per analysis, to quantitatively remove interfering zirconium and to measure precise and reproducible isotope values. Preliminary data will be presented to illustrate potential applications for this new paleoredox proxy. This technique will allow for the measurement of molybdenum isotopic ratios at low concentrations, expanding the breath of compounds and

Climax-Type Porphyry Molybdenum Deposits

USGS Publications Warehouse

Ludington, Steve; Plumlee, Geoffrey S.

2009-01-01

Climax-type porphyry molybdenum deposits, as defined here, are extremely rare; thirteen deposits are known, all in western North America and ranging in age from Late Cretaceous to mainly Tertiary. They are consistently found in a postsubduction, extensional tectonic setting and are invariably associated with A-type granites that formed after peak activity of a magmatic cycle. The deposits consist of ore shells of quartz-molybdenite stockwork veins that lie above and surrounding the apices of cupola-like, highly evolved, calc-alkaline granite and subvolcanic rhyolite-porphyry bodies. These plutons are invariably enriched in fluorine (commonly >1 percent), rubidium (commonly >500 parts per million), and niobium-tantalum (Nb commonly >50 parts per million). The deposits are relatively high grade (typically 0.1-0.3 percent Mo) and may be very large (typically 100-1,000 million tons). Molybdenum, as MoS2, is the primary commodity in all known deposits. The effect on surface-water quality owing to natural influx of water or sediment from a Climax-type mineralized area can extend many kilometers downstream from the mineralized area. Waste piles composed of quartz-silica-pyrite altered rocks will likely produce acidic drainage waters. The potential exists for concentrations of fluorine or rare metals in surface water and groundwater to exceed recommended limits for human consumption near both mined and unmined Climax-type deposits.

The interface in tungsten fiber reinforced niobium metal-matrix composites. Final Report Ph.D. Thesis - Case Western Reserve Univ., Cleveland, OH

NASA Technical Reports Server (NTRS)

Grobstein, Toni L.

1989-01-01

The creep resistance of tungsten fiber reinforced niobium metal-matrix composites was evaluated. The interface region between the fiber and matrix was characterized by microhardness and electron probe microanalysis measurements which indicated that its properties were between those of fiber and matrix. However, the measured properties of the composite exceeded those calculated by the rule of mixtures even when the interface zone was assumed to retain all the strength of the fiber. The composite structure appeared to enhance the strengths of both the fibers and the matrix above what they exhibited in stand-alone tests. The effect of fiber orientation and matrix alloy composition on the fiber/matrix interface were also evaluated. Small alloying additions of zirconium and tungsten to the niobium matrix affected the creep resistance of the composites only slightly. A decrease in the creep resistance of the composite with increasing zirconium content in the matrix was ascribed to an increase in the diffusion rate of the fiber/matrix interdiffusion reaction, and a slight increase in the creep resistance of the composite was observed with an addition of 9 w percent tungsten to the matrix. In addition, Kirkendall void formation was observed at the fiber/matrix interface; the void distribution differed depending on the fiber orientation relative to the stress axis.

METHOD OF MAKING METAL BONDED CARBON BODIES

DOEpatents

Goeddel, W.V.; Simnad, M.T.

1961-09-26

A method of producing carbon bodies having high structural strength and low permeability is described. The method comprises mixing less than 10 wt.% of a diffusional bonding material selected from the group consisting of zirconium, niobium, molybdenum, titanium, nickel, chromium, silicon, and decomposable compounds thereof with finely divided particles of carbon or graphite. While being maintained at a mechanical pressure over 3,000 psi, the mixture is then heated uniformly to a temperature of 1500 deg C or higher, usually for less than one hour. The resulting carbon bodies have a low diffusion constant, high dimensional stability, and high mechanical strength.

Electroless deposition process for zirconium and zirconium alloys

DOEpatents

Donaghy, R. E.; Sherman, A. H.

1981-08-18

A method is disclosed for preventing stress corrosion cracking or metal embrittlement of a zirconium or zirconium alloy container that is to be coated on the inside surface with a layer of a metal such as copper, a copper alloy, nickel, or iron and used for holding nuclear fuel material as a nuclear fuel element. The zirconium material is etched in an etchant solution, desmutted mechanically or ultrasonically, oxidized to form an oxide coating on the zirconium, cleaned in an aqueous alkaline cleaning solution, activated for electroless deposition of a metal layer and contacted with an electroless metal plating solution. This method provides a boundary layer of zirconium oxide between the zirconium container and the metal layer. 1 fig.

Electroless deposition process for zirconium and zirconium alloys

DOEpatents

Donaghy, Robert E.; Sherman, Anna H.

1981-01-01

A method is disclosed for preventing stress corrosion cracking or metal embrittlement of a zirconium or zirconium alloy container that is to be coated on the inside surface with a layer of a metal such as copper, a copper alloy, nickel, or iron and used for holding nuclear fuel material as a nuclear fuel element. The zirconium material is etched in an etchant solution, desmutted mechanically or ultrasonically, oxidized to form an oxide coating on the zirconium, cleaned in an aqueous alkaline cleaning solution, activated for electroless deposition of a metal layer and contacted with an electroless metal plating solution. This method provides a boundary layer of zirconium oxide between the zirconium container and the metal layer.

METHOD OF PRODUCING NIOBIUM METAL

DOEpatents

Wilhelm, H.A.; Stevens, E.R.

1960-05-24

A process is given for preparing ductile niobium metal by the reduction of niobium pentoxide with carbon. The invention resides in the addition, to the reaction mass, of from 0.05 to 0.4 atom of titanium (in the form of metallic titanium, titanium carbide, and/or titanium oxide) per one mole of niobium pentoxide. The mixture is heated under subatmospheric pressure to above 1300 deg C but below the melting point of niobium, and the carbon- and oxygen-free niobium sponge obtained is cooled under reduced pressure.

Molybdenum, molybdenum oxides, and their electrochemistry.

PubMed

Saji, Viswanathan S; Lee, Chi-Woo

2012-07-01

The electrochemical behaviors of molybdenum and its oxides, both in bulk and thin film dimensions, are critical because of their widespread applications in steels, electrocatalysts, electrochromic materials, batteries, sensors, and solar cells. An important area of current interest is electrodeposited CIGS-based solar cells where a molybdenum/glass electrode forms the back contact. Surprisingly, the basic electrochemistry of molybdenum and its oxides has not been reviewed with due attention. In this Review, we assess the scattered information. The potential and pH dependent active, passive, and transpassive behaviors of molybdenum in aqueous media are explained. The major surface oxide species observed, reversible redox transitions of the surface oxides, pseudocapacitance and catalytic reduction are discussed along with carefully conducted experimental results on a typical molybdenum glass back contact employed in CIGS-based solar cells. The applications of molybdenum oxides and the electrodeposition of molybdenum are briefly reviewed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Niobium and tantalum

USGS Publications Warehouse

Schulz, Klaus J.; Piatak, Nadine M.; Papp, John F.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

2017-12-19

Niobium and tantalum are transition metals that are almost always found together in nature because they have very similar physical and chemical properties. Their properties of hardness, conductivity, and resistance to corrosion largely determine their primary uses today. The leading use of niobium (about 75 percent) is in the production of high-strength steel alloys used in pipelines, transportation infrastructure, and structural applications. Electronic capacitors are the leading use of tantalum for high-end applications, including cell phones, computer hard drives, and such implantable medical devices as pacemakers. Niobium and tantalum are considered critical and strategic metals based on the potential risks to their supply (because current production is restricted to only a few countries) and the significant effects that a restriction in supply would have on the defense, energy, high-tech industrial, and medical sectors.The average abundance of niobium and tantalum in bulk continental crust is relatively low—8.0 parts per million (ppm) niobium and 0.7 ppm tantalum. Their chemical characteristics, such as small ionic size and high electronic field strength, significantly reduce the potential for these elements to substitute for more common elements in rock-forming minerals and make niobium and tantalum essentially immobile in most aqueous solutions. Niobium and tantalum do not occur naturally as pure metals but are concentrated in a variety of relatively rare oxide and hydroxide minerals, as well as in a few rare silicate minerals. Niobium is primarily derived from the complex oxide minerals of the pyrochlore group ((Na,Ca,Ce)2(Nb,Ti,Ta)2(O,OH,F)7), which are found in some alkaline granite-syenite complexes (that is, igneous rocks containing sodium- or potassium-rich minerals and little or no quartz) and carbonatites (that is, igneous rocks that are more than 50 percent composed of primary carbonate minerals, by volume). Tantalum is derived mostly from the

Proton in SRF Niobium

NASA Astrophysics Data System (ADS)

Wallace, John Paul

2011-03-01

Hydrogen is a difficult impurity to physically deal with in superconducting radio frequency (SRF) niobium, therefore, its properties in the metals should be well understood to allow the metal's superconducting properties to be optimized for minimum loss in the construction of resonant accelerator cavities. It is known that hydrogen is a paramagnetic impurity in niobium from NMR studies. This paramagnetism and its effect on superconducting properties are important to understand. To that end analytical induction measurements aimed at isolating the magnetic properties of hydrogen in SRF niobium are introduced along with optical reflection spectroscopy which is also sensitive to the presence of hydrogen. From the variety, magnitude and rapid kinetics found in the optical and magnetic properties of niobium contaminated with hydrogen forced a search for an atomic model. This yielded quantum mechanical description that correctly generates the activation energy for diffusion of the proton and its isotopes not only in niobium but the remaining metals for which data is available. This interpretation provides a frame work for understanding the individual and collective behavior of protons in metals.

Method of surface preparation of niobium

DOEpatents

Srinivasan-Rao, Triveni; Schill, John F.

2003-01-01

The present invention is for a method of preparing a surface of niobium. The preparation method includes polishing, cleaning, baking and irradiating the niobium surface whereby the resulting niobium surface has a high quantum efficiency.

Niobium powder synthesized by calciothermic reduction of niobium hydroxide for use in capacitors

NASA Astrophysics Data System (ADS)

Baba, Masahiko; Kikuchi, Tatsuya; Suzuki, Ryosuke O.

2015-03-01

Metallic niobium powder was produced for applications in electric capacitors via calciothermic reduction of niobium hydroxide in molten CaCl2. Sub-micrometer spherical metallic particles with coral-like morphologies reflected the particle size of the starting oxide powder. A fine powder was obtained from the mixtures of niobium hydroxide and CaO or Ca(OH)2, respectively. Sintered pellets of the metallic powder showed a higher capacitance (CV) than those of the simply reduced powder without pre-treatment, because the shrinkage during sintering was smaller. The CV was as large as that of commercially sintered pellets for tantalum capacitors. Therefore, this niobium powder would act as a higher-voltage capacitor by applying chemical anodic treatment at higher voltages, and lower oxygen content in the reduced power could realize a lower leak current.

Niobium and tantalum: indispensable twins

USGS Publications Warehouse

Schulz, Klaus; Papp, John

2014-01-01

Niobium and tantalum are transition metals almost always paired together in nature. These “twins” are difficult to separate because of their shared physical and chemical properties. In 1801, English chemist Charles Hatchett uncovered an unknown element in a mineral sample of columbite; John Winthrop found the sample in a Massachusetts mine and sent it to the British Museum in London in 1734. The name columbium, which Hatchet named the new element, came from the poetic name for North America—Columbia—and was used interchangeably for niobium until 1949, when the name niobium became official. Swedish scientist Anders Ekberg discovered tantalum in 1802, but it was confused with niobium, because of their twinned properties, until 1864, when it was recognized as a separate element. Niobium is a lustrous, gray, ductile metal with a high melting point, relatively low density, and superconductor properties. Tantalum is a dark blue-gray, dense, ductile, very hard, and easily fabricated metal. It is highly conductive to heat and electricity and renowned for its resistance to acidic corrosion. These special properties determine their primary uses and make niobium and tantalum indispensable.

METHOD FOR COATING GRAPHITE WITH NIOBIUM CARBIDE

DOEpatents

Kane, J.S.; Carpenter, J.H.; Krikorian, O.H.

1962-01-16

A method is given for coating graphite with a hard, tenacious layer of niobium carbide up to 30 mils or more thick. The method makes use of the discovery that niobium metal, if degassed and heated rapidly below the carburization temperature in contact with graphite, spreads, wets, and penetrates the graphite without carburization. The method includes the obvious steps of physically contacting niobium powders or other physical forms of niobium with graphite, degassing the assembly below the niobium melting point, e.g., 1400 deg C, heating to about 2200 to 2400 deg C within about 15 minutes while outgassing at a high volume throughput, and thereafter carburizing the niobium. (AEC)

Metal/ceramic composites with high hydrogen permeability

DOEpatents

Dorris, Stephen E.; Lee, Tae H.; Balachandran, Uthamalingam

2003-05-27

A membrane for separating hydrogen from fluids is provided comprising a sintered homogenous mixture of a ceramic composition and a metal. The metal may be palladium, niobium, tantalum, vanadium, or zirconium or a binary mixture of palladium with another metal such as niobium, silver, tantalum, vanadium, or zirconium.

High weldability nickel-base superalloy

DOEpatents

Gibson, Robert C.; Korenko, Michael K.

1980-01-01

This is a nickel-base superalloy with excellent weldability and high strength. Its composition consists essentially of, by weight percent, 10-20 iron, 57-63 nickel, 7-18 chromium, 4-6 molybdenum, 1-2 niobium, 0.2-0.8 silicon, 0.01-0.05 zirconium, 1.0-2.5 titanium, 1.0-2.5 aluminum, 0.02-0.06 carbon, and 0.002-0.015 boron. The weldability and strength of this alloy give it a variety of applications. The long-time structural stability of this alloy together with its low swelling under nuclear radiation conditions, make it especially suitable for use as a duct material and controlling element cladding for sodium-cooled nuclear reactors.

Nickel aluminide alloy suitable for structural applications

DOEpatents

Liu, Chain T.

1998-01-01

Alloys for use in structural applications based upon NiAl to which are added selected elements to enhance room temperature ductility and high temperature strength. Specifically, small additions of molybdenum produce a beneficial alloy, while further additions of boron, carbon, iron, niobium, tantalum, zirconium and hafnium further improve performance of alloys at both room temperature and high temperatures. A preferred alloy system composition is Ni--(49.1.+-.0.8%)Al--(1.0.+-.0.8%)Mo--(0.7.+-.0.5%)Nb/Ta/Zr/Hf--(nearly zero to 0.03%)B/C, where the % is at. % in each of the concentrations. All alloys demonstrated good oxidation resistance at the elevated temperatures. The alloys can be fabricated into components using conventional techniques.

The mineral resource potential of the Harrat Nawasif, sheet 21/42 C, Ranyah, sheet 21/42 D, and Jabal Dalfa, sheet 21/43 C quadrangles, Kingdom of Saudi Arabia

USGS Publications Warehouse

Fenton, Michael D.

1983-01-01

Areas with mineral resource potential in the Harrat Nawasif, Ranyah, and Jabal Dalfa quadrangles in the central Precambrian Shield of Saudi Arabia have been identified by reconnaissance rock geochemistry and inspection of ancient prospects. Locally anomalous areas in perthitic, alkalic granite terrane in the Ranyah quadrangle possibly contain niobium, zirconium, thorium, fluorite, rare-earth, tin, molybdenum, or copper mineralization. The reconnaissance rock geochemical survey in layered volcanic and volcaniclastic terrane in the Jabal Dalfa quadrangle identified a zinc anomaly in quartzite and a nickel-copper zone that is an extension of the Jabal Judayr prospect, where a low-grade, nickel-copper sulfide deposit is known. The Precambrian terrane in the Harrat Nawasif quadrangle has no known mineral resource potential.

Large grain cavities from pure niobium ingot

DOEpatents

Myneni, Ganapati Rao [Yorktown, VA; Kneisel, Peter [Williamsburg, VA; Cameiro, Tadeu [McMurray, PA

2012-03-06

Niobium cavities are fabricated by the drawing and ironing of as cast niobium ingot slices rather than from cold rolled niobium sheet. This method results in the production of niobium cavities having a minimum of grain boundaries at a significantly reduced cost as compared to the production of such structures from cold rolled sheet.

Vapor deposition of hardened niobium

DOEpatents

Blocher, Jr., John M.; Veigel, Neil D.; Landrigan, Richard B.

1983-04-19

A method of coating ceramic nuclear fuel particles containing a major amount of an actinide ceramic in which the particles are placed in a fluidized bed maintained at ca. 800.degree. to ca. 900.degree. C., and niobium pentachloride vapor and carbon tetrachloride vapor are led into the bed, whereby niobium metal is deposited on the particles and carbon is deposited interstitially within the niobium. Coating apparatus used in the method is also disclosed.

Process for alloying uranium and niobium

DOEpatents

Holcombe, Cressie E.; Northcutt, Jr., Walter G.; Masters, David R.; Chapman, Lloyd R.

1991-01-01

Alloys such as U-6Nb are prepared by forming a stacked sandwich array of uraniun sheets and niobium powder disposed in layers between the sheets, heating the array in a vacuum induction melting furnace to a temperature such as to melt the uranium, holding the resulting mixture at a temperature above the melting point of uranium until the niobium dissolves in the uranium, and casting the uranium-niobium solution. Compositional uniformity in the alloy product is enabled by use of the sandwich structure of uranium sheets and niobium powder.

Vapor deposition of molybdenum oxide using bis(ethylbenzene) molybdenum and water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Drake, Tasha L.; Stair, Peter C., E-mail: pstair@u.northwestern.edu

2016-09-15

Three molybdenum precursors—bis(acetylacetonate) dioxomolybdenum, molybdenum isopropoxide, and bis(ethylbenzene) molybdenum—were tested for molybdenum oxide vapor deposition. Quartz crystal microbalance studies were performed to monitor growth. Molybdenum isopropoxide and bis(ethylbenzene) molybdenum achieved linear growth rates 0.01 and 0.08 Å/cycle, respectively, using atomic layer deposition techniques. Negligible MoO{sub x} growth was observed on alumina powder using molybdenum isopropoxide, as determined by inductively coupled plasma optical emission spectroscopy. Bis(ethylbenzene) molybdenum achieved loadings of 0.5, 1.1, and 1.9 Mo/nm{sup 2} on alumina powder after one, two, and five cycles, respectively, using atomic layer deposition techniques. The growth window for bis(ethylbenzene) molybdenum is 135–150 °C. An alternative pulsingmore » strategy was also developed for bis(ethylbenzene) molybdenum that results in higher growth rates in less time compared to atomic layer deposition techniques. The outlined process serves as a methodology for depositing molybdenum oxide for catalytic applications. All as-deposited materials undergo further calcination prior to characterization and testing.« less

Catalytic determination of molybdenum(VI) by means of an iodide ion-selective electrode and a landolt-type hydrogen peroxide-iodide reaction.

PubMed

Kataoka, M; Nishimura, K; Kambara, T

1983-12-01

A trace amount of molybdenum(VI) can be determined by using its catalytic effect on the oxidation of iodide to iodine by hydrogen peroxide in acidic medium. Addition of ascorbic acid added to the reaction mixture produces the Landolt effect, i.e., the iodine produced by the indicator reaction is reduced immediately by the ascorbic add. Hence the concentration of iodide begins to decrease once all the ascorbic acid has been consumed. The induction period is measured by monitoring the concentration of iodide ion with an iodide ion-selective electrode. The reciprocal of the induction period varies linearly with the concentration of molybdenum(VI). The most suitable pH and concentrations of hydrogen peroxide and potassium iodide are found to be 1.5, 5 and 10mM, respectively. An appropriate amount of ascorbic acid is added to the reaction mixture according to the concentration of molybdenum(VI) in the sample solution. A calibration graph with good proportionality is obtained for the molybdenum(VI) concentration range from 0.1 to 160 muM. Iron(III), vanadium(IV), zirconium(IV), tungsten(VI), copper(II) and chromium(VI) interfere, but iron(III) and copper(II) can be masked with EDTA.

Method of nitriding niobium to form a superconducting surface

DOEpatents

Kelley, Michael J.; Klopf, John Michael; Singaravelu, Senthilaraja

2014-08-19

A method of forming a delta niobium nitride .delta.-NbN layer on the surface of a niobium object including cleaning the surface of the niobium object; providing a treatment chamber; placing the niobium object in the treatment chamber; evacuating the chamber; passing pure nitrogen into the treatment chamber; focusing a laser spot on the niobium object; delivering laser fluences at the laser spot until the surface of the niobium object reaches above its boiling temperature; and rastering the laser spot over the surface of the niobium object.

[Study on the determination of trace gallium in molybdenum-coated pyrolytic graphite tube by electrothermal absorption spectrometry].

PubMed

Huang, Yu-an; Zhou, Fang-qin; Long, Si-hua; Yang, Liu

2004-02-01

The effects on gallium atomization in the pyrolytic graphite tube imposed by different matrix modifiers and different coatings were discussed detailedly in this paper. In the presence of matrix modifier of Ni(NO3)2 the matrix interference was eliminated efficiently. The pyrolytic graphite tubes were coated differently with lanthanum, zirconium, and molybdenum to avoid producing gallium carbide. Results showed that the tube with molybdenum coating was the best. On this basis, the mechanism of gallium atomization in the molybdenum-coated pyrolytic graphite tube using Ni(NO3)2 as a matrix modifier was studied furthermore; in addition, the parameters of the operation were optimized. As a result, a new method improved in many aspects was developed to detect trace gallium in complicated sample of gangue. The outcomes of practical applications indicated that the method could satisfy the requests of analysis and that the manipulations were simple to achieve. The characteristic content, the detection limit, and the adding recoveries were 2.12 x 10(-11) g, 1.4 x 10(-10) g and 97.4%-102.7% respectively, and the relative standard deviation was less than or equal to 3.6% (n = 11).

Zirconium and hafnium

USGS Publications Warehouse

Jones, James V.; Piatak, Nadine M.; Bedinger, George M.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

2017-12-19

Zirconium and hafnium are corrosion-resistant metals that are widely used in the chemical and nuclear industries. Most zirconium is consumed in the form of the main ore mineral zircon (ZrSiO4, or as zirconium oxide or other zirconium chemicals. Zirconium and hafnium are both refractory lithophile elements that have nearly identical charge, ionic radii, and ionic potentials. As a result, their geochemical behavior is generally similar. Both elements are classified as incompatible because they have physical and crystallochemical properties that exclude them from the crystal lattices of most rock-forming minerals. Zircon and another, less common, ore mineral, baddeleyite (ZrO2), form primarily as accessory minerals in igneous rocks. The presence and abundance of these ore minerals in igneous rocks are largely controlled by the element concentrations in the magma source and by the processes of melt generation and evolution. The world’s largest primary deposits of zirconium and hafnium are associated with alkaline igneous rocks, and, in one locality on the Kola Peninsula of Murmanskaya Oblast, Russia, baddeleyite is recovered as a byproduct of apatite and magnetite mining. Otherwise, there are few primary igneous deposits of zirconium- and hafnium-bearing minerals with economic value at present. The main ore deposits worldwide are heavy-mineral sands produced by the weathering and erosion of preexisting rocks and the concentration of zircon and other economically important heavy minerals, such as ilmenite and rutile (for titanium), chromite (for chromium), and monazite (for rare-earth elements) in sedimentary systems, particularly in coastal environments. In coastal deposits, heavy-mineral enrichment occurs where sediment is repeatedly reworked by wind, waves, currents, and tidal processes. The resulting heavy-mineral-sand deposits, called placers or paleoplacers, preferentially form at relatively low latitudes on passive continental margins and supply 100 percent of

One hundred angstrom niobium wire

NASA Technical Reports Server (NTRS)

Cline, H. E.; Rose, R. M.; Wulff, J.

1968-01-01

Composite of fine niobium wires in copper is used to study the size and proximity effects of a superconductor in a normal matrix. The niobium rod was drawn to a 100 angstrom diameter wire on a copper tubing.

Determination of small amounts of molybdenum in tungsten and molybdenum ores

USGS Publications Warehouse

Grimaldi, F.S.; Wells, R.C.

1943-01-01

A rapid method has been developed for the determination of small amounts of molybdenum in tungsten and molybdenum ores. After removing iron and other major constituents the molybdenum thiocyanate color is developed in water-acetone solutions, using ammonium citrate to eliminate the interference of tungsten. Comparison is made by titrating a blank with a standard molybdenum solution. Aliquots are adjusted to deal with amounts of molybdenum ranging from 0.01 to 1.30 mg.

Mechanical properties of electron-beam-melted molybdenum and dilute molybdenum-rhenium alloys

NASA Technical Reports Server (NTRS)

Klopp, W. D.; Witzke, W. R.

1972-01-01

A study of molybdenum and three dilute molybdenum-rhenium alloys was undertaken to determine the effects of rhenium on the low temperature ductility and other mechanical properties of molybdenum. Alloys containing 3.9, 5.9, and 7.7 atomic percent rhenium exhibited lower ductile-brittle transition temperatures than did the unalloyed molybdenum. The maximum improvement in the annealed condition was observed for molybdenum - 7.7 rhenium, which had a ductile-brittle transition temperature approximately 200 C (360 F) lower than that for unalloyed molybdenum. Rhenium additions also increased the low and high temperature tensile strengths and the high temperature creep strength of molybdenum. The mechanical behavior of dilute molybdenum-rhenium alloys is similar to that observed for dilute tungsten-rhenium alloys.

Molybdenum in the environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jawell, W.M.; Page, A.L.; Elseewi, A.A.

1980-01-01

While molybdenum is an essential element for both plants and animals, it becomes toxic above certain critical levels. Reviewed are the natural supply of molybdenum in the environment. The molybdenum cycle, the importance of molybdenum in industry and agriculture, and potential hazards that may occur when excessive levels of molybdenum occur in the environment. Although the potential of molybdenum toxicity to humans and non-ruminant animals appears to be low, the enrichment of the environment with molybdenum from modern mining, agricultural, and industrial activities has potentially hazardous implications for ruminant animal health.

Iron aluminide alloys with improved properties for high temperature applications

DOEpatents

McKamey, Claudette G.; Liu, Chain T.

1990-01-01

An improved iron aluminide alloy of the DO.sub.3 type that has increased room temperature ductility and improved high elevated temperature strength. The alloy system further is resistant to corrosive attack in the environments of advanced energy corrosion systems such as those using fossil fuels. The resultant alloy is relatively inexpensive as contrasted to nickel based and high nickel steels currently utilized for structural components. The alloy system consists essentially of 26-30 at. % aluminum, 0.5-10 at. % chromium, 0.02-0.3 at. % boron plus carbon, up to 2 at. % molybdenum, up to 1 at. % niobium, up to 0.5 at. % zirconium, up to 0.1 at. % yttrium, up to 0.5 at. % vanadium and the balance iron.

Nickel aluminide alloy suitable for structural applications

DOEpatents

Liu, C.T.

1998-03-10

Alloys are disclosed for use in structural applications based upon NiAl to which are added selected elements to enhance room temperature ductility and high temperature strength. Specifically, small additions of molybdenum produce a beneficial alloy, while further additions of boron, carbon, iron, niobium, tantalum, zirconium and hafnium further improve performance of alloys at both room temperature and high temperatures. A preferred alloy system composition is Ni--(49.1{+-}0.8%)Al--(1.0{+-}0.8%)Mo--(0.7 + 0.5%)Nb/Ta/Zr/Hf--(nearly zero to 0.03%)B/C, where the % is at. % in each of the concentrations. All alloys demonstrated good oxidation resistance at the elevated temperatures. The alloys can be fabricated into components using conventional techniques. 4 figs.

Deep-ocean ferromanganese crusts and nodules

USGS Publications Warehouse

Hein, James R.; Koschinsky, Andrea

2014-01-01

Ferromanganese crusts and nodules may provide a future resource for a large variety of metals, including many that are essential for emerging high- and green-technology applications. A brief review of nodules and crusts provides a setting for a discussion on the latest (past 10 years) research related to the geochemistry of sequestration of metals from seawater. Special attention is given to cobalt, nickel, titanium, rare earth elements and yttrium, bismuth, platinum, tungsten, tantalum, hafnium, tellurium, molybdenum, niobium, zirconium, and lithium. Sequestration from seawater by sorption, surface oxidation, substitution, and precipitation of discrete phases is discussed. Mechanisms of metal enrichment reflect modes of formation of the crusts and nodules, such as hydrogenetic (from seawater), diagenetic (from porewaters), and mixed diagenetic–hydrogenetic processes.

METHOD OF MAKING FUEL BODIES

DOEpatents

Goeddel, W.V.; Simnad, M.T.

1963-04-30

This patent relates to a method of making a fuel compact having a matrix of carbon or graphite which carries the carbides of fissile material. A nuclear fuel material selected from the group including uranium and thorium carbides, silicides, and oxides is first mixed both with sufficient finely divided carbon to constitute a matrix in the final product and with a diffusional bonding material selected from the class consisting of zirconium, niobium, molybdenum, titanium, nickel, chromium, and silicon. The mixture is then heated at a temperature of 1500 to 1800 nif- C while maintaining it under a pressure of over about 2,000 pounds per square inch. Preferably, heating is accomplished by the electrical resistance of the compact itself. (AEC)

High temperature coatings for gas turbines

DOEpatents

Zheng, Xiaoci Maggie

2003-10-21

Coating for high temperature gas turbine components that include a MCrAlX phase, and an aluminum-rich phase, significantly increase oxidation and cracking resistance of the components, thereby increasing their useful life and reducing operating costs. The aluminum-rich phase includes aluminum at a higher concentration than aluminum concentration in the MCrAlX alloy, and an aluminum diffusion-retarding composition, which may include cobalt, nickel, yttrium, zirconium, niobium, molybdenum, rhodium, cadmium, indium, cerium, iron, chromium, tantalum, silicon, boron, carbon, titanium, tungsten, rhenium, platinum, and combinations thereof, and particularly nickel and/or rhenium. The aluminum-rich phase may be derived from a particulate aluminum composite that has a core comprising aluminum and a shell comprising the aluminum diffusion-retarding composition.

Iron aluminide alloys with improved properties for high temperature applications

DOEpatents

McKamey, C.G.; Liu, C.T.

1990-10-09

An improved iron aluminide alloy of the DO[sub 3] type is described that has increased room temperature ductility and improved high elevated temperature strength. The alloy system further is resistant to corrosive attack in the environments of advanced energy conversion systems such as those using fossil fuels. The resultant alloy is relatively inexpensive as contrasted to nickel based and high nickel steels currently utilized for structural components. The alloy system consists essentially of 26--30 at. % aluminum, 0.5--10 at. % chromium, 0.02--0.3 at. % boron plus carbon, up to 2 at. % molybdenum, up to 1 at. % niobium, up to 0.5 at. % zirconium, up to 0.1 at. % yttrium, up to 0.5 at. % vanadium and the balance iron. 3 figs.

Molybdenum in the environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jarrell, W.M.; Page, A.L.; Elseewi, A.A.

1980-01-01

While molybdenum is an essential element for both plants and animals, it becomes toxic above certain critical levels. Reviewed are the natural supply of molybdenum in the environment, the molybdenum cycle, the importance of molybdenum in industry and agriculture, and potential hazards that may occur when excessive levels of molybdenum occur in the environment. Although the potential of molybdenum toxicity to humans and non-ruminant animals appears to be low, the enrichment of the environment with molybdenum from modern mining, agricultural, and industrial activities has potentially hazardous implications for ruminant animal health. (3 graphs, numerous references, 16 tables)

PLUTONIUM-ZIRCONIUM ALLOYS

DOEpatents

Schonfeld, F.W.; Waber, J.T.

1960-08-30

A series of nuclear reactor fuel alloys consisting of from about 5 to about 50 at.% zirconium (or higher zirconium alloys such as Zircaloy), balance plutonium, and having the structural composition of a plutonium are described. Zirconium is a satisfactory diluent because it alloys readily with plutonium and has desirable nuclear properties. Additional advantages are corrosion resistance, excellent fabrication propenties, an isotropie structure, and initial softness.

Development of Self-Healing Zirconium-Silicide Coatings for Improved Performance Zirconium-Alloy Fuel Cladding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sridharan, Kumar; Mariani, Robert; Bai, Xianming

Zirconium-alloy fuel claddings have been used successfully in Light Water Reactors (LWR) for over four decades. However, under high temperature accident conditions, zirconium-alloys fuel claddings exhibit profuse exothermic oxidation accompanied by release of hydrogen gas due to the reaction with water/steam. Additionally, the ZrO 2 layer can undergo monoclinic to tetragonal to cubic phase transformations at high temperatures which can induce stresses and cracking. These events were unfortunately borne out in the Fukushima-Daiichi accident in in Japan in 2011. In reaction to such accident, protective oxidation-resistant coatings for zirconium-alloy fuel claddings has been extensively investigated to enhance safety margins inmore » accidents as well as fuel performance under normal operation conditions. Such surface modification could also beneficially affect fuel rod heat transfer characteristics. Zirconium-silicide, a candidate coating material, is particularly attractive because zirconium-silicide coating is expected to bond strongly to zirconium-alloy substrate. Intermetallic compound phases of zirconium-silicide have high melting points and oxidation of zirconium silicide produces highly corrosion resistant glassy zircon (ZrSiO 4) and silica (SiO 2) which possessing self-healing qualities. Given the long-term goal of developing such coatings for use with nuclear reactor fuel cladding, this work describes results of oxidation and corrosion behavior of bulk zirconium-silicide and fabrication of zirconium-silicide coatings on zirconium-alloy test flats, tube configurations, and SiC test flats. In addition, boiling heat transfer of these modified surfaces (including ZrSi 2 coating) during clad quenching experiments is discussed in detail.« less

ZIRCONIUM-CLADDING OF THORIUM

DOEpatents

Beaver, R.J.

1961-11-21

A method of cladding thorium with zirconium is described. The quality of the bond achieved between thorium and zirconium by hot-rolling is improved by inserting and melting a thorium-zirconium alloy foil between the two materials prior to rolling. (AEC)

Oxide strengthened molybdenum-rhenium alloy

DOEpatents

Bianco, Robert; Buckman, Jr., R. William

2000-01-01

Provided is a method of making an ODS molybdenum-rhenium alloy which includes the steps of: (a) forming a slurry containing molybdenum oxide and a metal salt dispersed in an aqueous medium, the metal salt being selected from nitrates or acetates of lanthanum, cerium or thorium; (b) heating the slurry in the presence of hydrogen to form a molybdenum powder comprising molybdenum and an oxide of the metal salt; (c) mixing rhenium powder with the molybdenum powder to form a molybdenum-rhenium powder; (d) pressing the molybdenum-rhenium powder to form a molybdenum-rhenium compact; (e) sintering the molybdenum-rhenium compact in hydrogen or under a vacuum to form a molybdenum-rhenium ingot; and (f) compacting the molybdenum-rhenium ingot to reduce the cross-sectional area of the molybdenum-rhenium ingot and form a molybdenum-rhenium alloy containing said metal oxide. The present invention also provides an ODS molybdenum-rhenium alloy made by the method. A preferred Mo--Re-ODS alloy contains 7-14 weight % rhenium and 2-4 volume % lanthanum oxide.

Evaluating the Surface Characteristics of Stainless Steel, TMA, Timolium, and Titanium-niobium Wires: An in vivo Scanning Electron Microscope Study.

PubMed

Babu, K Pradeep; Keerthi, V Naga; Madathody, Deepika; Prasanna, A Laxmi; Gopinath, Vidhya; Kumar, M Senthil; Kumar, A Nanda

2016-05-01

Recent metallurgical research and advancement in material science has benefited orthodontists in the selection of an appropriate wire size and alloy type, which is necessary to provide an optimum and predictable treatment results. The purpose of the study was to clinically evaluate and compare the surface characteristics of 16 x 22 stainless steel, Titanium molybdenum alloy, timolium, and titanium-niobium before and after placing them in a patient's mouth for 3 months using a scanning electron microscope (SEM). The total sample size was 40, which were divided into four groups (group 1 - stainless steel wires, 10 samples, group 2 - TMA wires, 10 samples, group 3 - timolium wires, 10 samples, and group 4 - titanium-niobium wires, 10 samples), and these were further subdivided into 5 each. The first subgroup of five samples was placed in the patient's mouth and was evaluated under SEM, and another subgroup of five samples was directly subjected to the SEM. Scanning electron microscopic evaluation of surface characteristics of unused 16 x 22 rectangular stainless steel wire under 500 x magnification showed an overall smooth surface. Stainless steel wire samples placed in the patient's mouth showed black hazy patches, which may be interoperated as areas of stress. TMA unused wires showed multiple small voids of areas and small craters with fewer elevated regions. The TMA wire samples placed in the patient's mouth showed black hazy patches and prominent ridges, making the wire rougher. Timolium unused archwires showed heavy roughness and voids, whereas wires tested in the patient's mouth showed homogeneous distribution of deep cracks and craters. Unused titanium-niobium archwires showed uniform prominent striations and ridges with occasional voids, whereas wires used in the patient's mouth showed prominent huge voids that could be interpreted as maximum stress areas. Stainless steel (group 1) used and unused wires showed smooth surface characteristics when compared with

Molybdenum disilicide composites

DOEpatents

Rodriguez, Robert P.; Petrovic, John J.

2001-01-01

Molybdenum disilicide/.beta.'-Si.sub.6-z Al.sub.z O.sub.z N.sub.8-z, wherein z=a number from greater than 0 to about 5, composites are made by use of in situ reactions among .alpha.-silicon nitride, molybdenum disilicide, and aluminum. Molybdenum disilicide within a molybdenum disilicide/.beta.'-Si.sub.6-z Al.sub.z O.sub.z N.sub.8-z eutectoid matrix is the resulting microstructure when the invention method is employed.

PROCESS OF COATING GRAPHITE WITH NIOBIUM-TITANIUM CARBIDE

DOEpatents

Halden, F.A.; Smiley, W.D.; Hruz, F.M.

1961-07-01

A process of coating graphite with niobium - titanium carbide is described. It is found that the addition of more than ten percent by weight of titanium to niobium results in much greater wetting of the graphite by the niobium and a much more adherent coating. The preferred embodiment comprises contacting the graphite with a powdered alloy or mixture, degassing simultaneously the powder and the graphite, and then heating them to a high temperature to cause melting, wetting, spreading, and carburization of the niobium-titanium powder.

Artefacts in multimodal imaging of titanium, zirconium and binary titanium–zirconium alloy dental implants: an in vitro study

PubMed Central

Schöllchen, Maximilian; Aarabi, Ghazal; Assaf, Alexandre T; Rendenbach, Carsten; Beck-Broichsitter, Benedicta; Semmusch, Jan; Sedlacik, Jan; Heiland, Max; Fiehler, Jens; Siemonsen, Susanne

2017-01-01

Objectives: To analyze and evaluate imaging artefacts induced by zirconium, titanium and titanium–zirconium alloy dental implants. Methods: Zirconium, titanium and titanium–zirconium alloy implants were embedded in gelatin and MRI, CT and CBCT were performed. Standard protocols were used for each modality. For MRI, line–distance profiles were plotted to quantify the accuracy of size determination. For CT and CBCT, six shells surrounding the implant were defined every 0.5 cm from the implant surface and histogram parameters were determined for each shell. Results: While titanium and titanium–zirconium alloy induced extensive signal voids in MRI owing to strong susceptibility, zirconium implants were clearly definable with only minor distortion artefacts. For titanium and titanium–zirconium alloy, the MR signal was attenuated up to 14.1 mm from the implant. In CT, titanium and titanium–zirconium alloy resulted in less streak artefacts in comparison with zirconium. In CBCT, titanium–zirconium alloy induced more severe artefacts than zirconium and titanium. Conclusions: MRI allows for an excellent image contrast and limited artefacts in patients with zirconium implants. CT and CBCT examinations are less affected by artefacts from titanium and titanium–zirconium alloy implants compared with MRI. The knowledge about differences of artefacts through different implant materials and image modalities might help support clinical decisions for the choice of implant material or imaging device in the clinical setting. PMID:27910719

Artefacts in multimodal imaging of titanium, zirconium and binary titanium-zirconium alloy dental implants: an in vitro study.

PubMed

Smeets, Ralf; Schöllchen, Maximilian; Gauer, Tobias; Aarabi, Ghazal; Assaf, Alexandre T; Rendenbach, Carsten; Beck-Broichsitter, Benedicta; Semmusch, Jan; Sedlacik, Jan; Heiland, Max; Fiehler, Jens; Siemonsen, Susanne

2017-02-01

To analyze and evaluate imaging artefacts induced by zirconium, titanium and titanium-zirconium alloy dental implants. Zirconium, titanium and titanium-zirconium alloy implants were embedded in gelatin and MRI, CT and CBCT were performed. Standard protocols were used for each modality. For MRI, line-distance profiles were plotted to quantify the accuracy of size determination. For CT and CBCT, six shells surrounding the implant were defined every 0.5 cm from the implant surface and histogram parameters were determined for each shell. While titanium and titanium-zirconium alloy induced extensive signal voids in MRI owing to strong susceptibility, zirconium implants were clearly definable with only minor distortion artefacts. For titanium and titanium-zirconium alloy, the MR signal was attenuated up to 14.1 mm from the implant. In CT, titanium and titanium-zirconium alloy resulted in less streak artefacts in comparison with zirconium. In CBCT, titanium-zirconium alloy induced more severe artefacts than zirconium and titanium. MRI allows for an excellent image contrast and limited artefacts in patients with zirconium implants. CT and CBCT examinations are less affected by artefacts from titanium and titanium-zirconium alloy implants compared with MRI. The knowledge about differences of artefacts through different implant materials and image modalities might help support clinical decisions for the choice of implant material or imaging device in the clinical setting.

High strength nickel-chromium-iron austenitic alloy

DOEpatents

Gibson, Robert C.; Korenko, Michael K.

1980-01-01

A solid solution strengthened Ni-Cr-Fe alloy capable of retaining its strength at high temperatures and consisting essentially of 42 to 48% nickel, 11 to 13% chromium, 2.6 to 3.4% niobium, 0.2 to 1.2% silicon, 0.5 to 1.5% vanadium, 2.6 to 3.4% molybdenum, 0.1 to 0.3% aluminum, 0.1 to 0.3% titanium, 0.02 to 0.05% carbon, 0.002 to 0.015% boron, up to 0.06 zirconium, and the balance iron. After solution annealing at 1038.degree. C. for one hour, the alloy, when heated to a temperature of 650.degree. C., has a 2% yield strength of 307 MPa, an ultimate tensile strength of 513 MPa and a rupture strength of as high as 400 MPa after 100 hours.

Niobium oxide compositions and methods for using same

DOEpatents

Goodenough, John B; Han, Jian-Tao

2014-02-11

The disclosure relates a niobium oxide useful in anodes of secondary lithium ion batteries. Such niobium oxide has formula Li.sub.xM.sub.1-yNb.sub.yNb.sub.2O.sub.7, wherein 0.ltoreq.x.ltoreq.3, 0.ltoreq.y.ltoreq.1, and M represents Ti or Zr. The niobium oxide may be in the form of particles, which may be carbon coated. The disclosure also relates to an electrode composition containing at least one or more niobium oxides of formula Li.sub.xM.sub.1-yNb.sub.yNb.sub.2O.sub.7. The disclosure further relates to electrodes, such as anodes, and batteries containing at least one or more niobium oxides of formula Li.sub.xM.sub.1-yNb.sub.yNb.sub.2O.sub.7. Furthermore, the disclosure relates to methods of forming the above.

Development of a Database of Thermochemical Parameters for Use with the SOLGASMIX Computer Program

DTIC Science & Technology

1988-07-01

TITANIUM CHLORIDE (TICL4) CL4Wl(CR) TUNGSTEN CHLORIDE (WCL4) CL4Wl(G) TUNGSTEN CHLORIDE (WCL4) CL4ZR1(CR) ZIRCONIUM CHLORIDE ( ZRCL4 ) CL4ZR1(G) ZIRCONIUM...CHLORIDE ( ZRCL4 ) % % % CL5MO1(CR) MOLYBDENUM CHLORIDE (MOCL5) CL5MO1(CR,L) MOLYBDENUM CHLORIDE (MOCL5) CL5MO1(G) MOLYBDENUM CHLORIDE (MOCL5) CL5MOI(L

Niobium-bearing arsenides and germanides from elemental mixtures not involving niobium: a new twist to an old problem in solid-state synthesis.

PubMed

Baranets, Sviatoslav; He, Hua; Bobev, Svilen

2018-05-01

Three isostructural transition-metal arsenides and germanides, namely niobium nickel arsenide, Nb 0.92(1) NiAs, niobium cobalt arsenide, NbCoAs, and niobium nickel germanide, NbNiGe, were obtained as inadvertent side products of high-temperature reactions in sealed niobium containers. In addition to reporting for the very first time the structures of the title compounds, refined from single-crystal X-ray diffraction data, this article also serves as a reminder that niobium containers may not be suitable for the synthesis of ternary arsenides and germanides by traditional high-temperature reactions. Synthetic work involving alkali or alkaline-earth metals, transition or early post-transition metals, and elements from groups 14 or 15 under such conditions may yield Nb-containing products, which at times could be the major products of such reactions.

Molybdenum Trafficking for Nitrogen Fixation†

PubMed Central

Hernandez, Jose A.; George, Simon J.; Rubio, Luis M.

2009-01-01

The molybdenum nitrogenase is responsible for most biological nitrogen fixation, a prokaryotic metabolic process that determines the global biogeochemical cycles of nitrogen and carbon. Here we describe the trafficking of molybdenum for nitrogen fixation in the model diazotrophic bacterium Azotobacter vinelandii. The genes and proteins involved in molybdenum uptake, homeostasis, storage, regulation, and nitrogenase cofactor biosynthesis are reviewed. Molybdenum biochemistry in A. vinelandii reveals unexpected mechanisms and a new role for iron-sulfur clusters in the sequestration and delivery of molybdenum. PMID:19772354

Method of making crack-free zirconium hydride

DOEpatents

Sullivan, Richard W.

1980-01-01

Crack-free hydrides of zirconium and zirconium-uranium alloys are produced by alloying the zirconium or zirconium-uranium alloy with beryllium, or nickel, or beryllium and scandium, or nickel and scandium, or beryllium and nickel, or beryllium, nickel and scandium and thereafter hydriding.

Primary radiation damage of Zr-0.5%Nb binary alloy: atomistic simulation by molecular dynamics method

NASA Astrophysics Data System (ADS)

Tikhonchev, M.; Svetukhin, V.; Kapustin, P.

2017-09-01

Ab initio calculations predict high positive binding energy (˜1 eV) between niobium atoms and self-interstitial configurations in hcp zirconium. It allows the expectation of increased niobium fraction in self-interstitials formed under neutron irradiation in atomic displacement cascades. In this paper, we report the results of molecular dynamics simulation of atomic displacement cascades in Zr-0.5%Nb binary alloy and pure Zr at the temperature of 300 K. Two sets of n-body interatomic potentials have been used for the Zr-Nb system. We consider a cascade energy range of 2-20 keV. Calculations show close estimations of the average number of produced Frenkel pairs in the alloy and pure Zr. A high fraction of Nb is observed in the self-interstitial configurations. Nb is mainly detected in single self-interstitial configurations, where its fraction reaches tens of percent, i.e. more than its tenfold concentration in the matrix. The basic mechanism of this phenomenon is the trapping of mobile self-interstitial configurations by niobium. The diffusion of pure zirconium and mixed zirconium-niobium self-interstitial configurations in the zirconium matrix at 300 K has been simulated. We observe a strong dependence of the estimated diffusion coefficients and fractions of Nb in self-interstitials produced in displacement cascades on the potential.

Pure Niobium as a Pressure Vessel Material

NASA Astrophysics Data System (ADS)

Peterson, T. J.; Carter, H. F.; Foley, M. H.; Klebaner, A. L.; Nicol, T. H.; Page, T. M.; Theilacker, J. C.; Wands, R. H.; Wong-Squires, M. L.; Wu, G.

2010-04-01

Physics laboratories around the world are developing niobium superconducting radio frequency (SRF) cavities for use in particle accelerators. These SRF cavities are typically cooled to low temperatures by direct contact with a liquid helium bath, resulting in at least part of the helium container being made from pure niobium. In the U.S., the Code of Federal Regulations allows national laboratories to follow national consensus pressure vessel rules or use of alternative rules which provide a level of safety greater than or equal to that afforded by ASME Boiler and Pressure Vessel Code. Thus, while used for its superconducting properties, niobium ends up also being treated as a material for pressure vessels. This report summarizes what we have learned about the use of niobium as a pressure vessel material, with a focus on issues for compliance with pressure vessel codes. We present results of a literature search for mechanical properties and tests results, as well as a review of ASME pressure vessel code requirements and issues.

Modification in band gap of zirconium complexes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Mayank, E-mail: mayank30134@gmail.com; Singh, J.; Chouhan, S.

2016-05-06

The optical properties of zirconium complexes with amino acid based Schiff bases are reported here. The zirconium complexes show interesting stereo chemical features, which are applicable in organometallic and organic synthesis as well as in catalysis. The band gaps of both Schiff bases and zirconium complexes were obtained by UV-Visible spectroscopy. It was found that the band gap of zirconium complexes has been modified after adding zirconium compound to the Schiff bases.

Development and property evaluation of nuclear grade wrought FeCrAl fuel cladding for light water reactors

DOE PAGES

Yamamoto, Yukinori; Pint, Bruce A.; Terrani, Kurt A.; ...

2015-10-19

Development of nuclear grade, iron-based wrought FeCrAl alloys has been initiated for light water reactor (LWR) fuel cladding to serve as a substitute for zirconium-based alloys with enhanced accident tolerance. Ferritic alloys with sufficient chromium and aluminum additions can exhibit significantly improved oxidation kinetics in high-temperature steam environments when compared to zirconium-based alloys. In the first phase, a set of model FeCrAl alloys containing 10–20Cr, 3–5Al, and 0–0.12Y in weight percent, were prepared by conventional arc-melting and hot-working processes to explore the effect of composition on the properties of FeCrAlY alloys. It was found that the tensile properties were insensitivemore » to the alloy compositions studied; however, the steam oxidation resistance strongly depended on both the chromium and the aluminum contents. The second phase development focused on strengthening Fe-13Cr-5Al with minor alloying additions of molybdenum, niobium, and silicon. Combined with an optimized thermo-mechanical treatment, a thermally stable microstructure was produced with improved tensile properties at temperatures up to 741°C.« less

Precipitation hardenable iron-nickel-chromium alloy having good swelling resistance and low neutron absorbence

DOEpatents

Korenko, Michael K.; Merrick, Howard F.; Gibson, Robert C.

1980-01-01

An iron-nickel-chromium age-hardenable alloy suitable for use in fast breeder reactor ducts and cladding which utilizes the gamma-double prime strengthening phase and characterized in having a morphology of the gamma-double prime phase enveloping the gamma-prime phase and delta phase distributed at or near the grain boundaries. The alloy consists essentially of about 40-50% nickel, 7.5-14% chromium, 1.5-4% niobium, 0.25-0.75% silicon, 1-3% titanium, 0.1-0.5% aluminum, 0.02-0.1% carbon, 0.002-0.015% boron, and the balance iron. Up to 2% manganese and up to 0.01% magnesium may be added to inhibit trace element effects; up to 0.1% zirconium may be added to increase radiation swelling resistance; and up to 3% molybdenum may be added to increase strength.

SEPARATION PROCESS FOR ZIRCONIUM AND COMPOUNDS THEREOF

DOEpatents

Crandall, H.W.; Thomas, J.R.

1959-06-30

The separation of zirconium from columbium, rare earths, yttrium and the alkaline earth metals, such mixtures of elements occurring in zirconium ores or neutron irradiated uranium is described. According to the invention a suitable separation of zirconium from a one normal acidic aqueous solution containing salts, nitrates for example, of tetravalent zirconium, pentavalent columbium, yttrium, rare earths in the trivalent state and alkaline earths can be obtained by contacting the aqueous solution with a fluorinated beta diketonc alone or in an organic solvent solution, such as benzene, to form a zirconium chelate compound. When the organic solvent is present the zirconium chelate compound is directly extracted; otherwise it is separated by filtration. The zirconium may be recovered from contacting the organic solvent solution containing the chelated compound by back extraction with either an aqueous hydrofluoric acid or an oxalic acid solution.

Mineral Resource of the Month: Niobium

USGS Publications Warehouse

Papp, John F.

2014-01-01

Niobium, also called columbium, is a transition metal with a very high melting point. It is in greatest demand in industrialized countries, like the United States, because of its defense-related uses in the aerospace, energy and transportation industries. Niobium is used mostly to make high-strength, low-alloy (HSLA) steel and stainless steel. HSLA steels are used in large-diameter pipes for oil and natural gas pipelines and automobile wheels.

THE ANALYSIS OF URANIUM-ZIRCONIUM ALLOYS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Milner, G.W.C.; Skewies, A.F.

1953-03-01

A satisfactory procedure is described for the analysis of uranium-zirconium alloys containing up to 25% zirconium. It is based on the separation of the zirconium from the uranium by dissolving the cupferron complex of the former element into chloroform. After the evaporation of the solvent from the combined organic extracts, the residue is ignited to zirconium oxide. The latter is then re-dissolved and zirconium is separated from other elements co-extracted in the solvent extraction procedure by precipitation with mandelic acid. The zirconium mandelate is finally ignited to oxide at 960 deg C. The uranium is separated from the aqueous solutionmore » remaining from the cupferron extraction by precipitating with tannin at a pH of 8; the precipitate being removed by filtration and then ignited a t 800 deg C. The residue is dissolved in nitric acid and the uranium is finally determined by precipitating as ammonium diuranate and then igniting to U{sub 3}O{sub 8}. (auth)« less

Ablation Resistant Zirconium and Hafnium Ceramics

NASA Technical Reports Server (NTRS)

Bull, Jeffrey (Inventor); White, Michael J. (Inventor); Kaufman, Larry (Inventor)

1998-01-01

High temperature ablation resistant ceramic composites have been made. These ceramics are composites of zirconium diboride and zirconium carbide with silicon carbide, hafnium diboride and hafnium carbide with silicon carbide and ceramic composites which contain mixed diborides and/or carbides of zirconium and hafnium. along with silicon carbide.

Method for preparing hydrous zirconium oxide gels and spherules

DOEpatents

Collins, Jack L.

2003-08-05

Methods for preparing hydrous zirconium oxide spherules, hydrous zirconium oxide gels such as gel slabs, films, capillary and electrophoresis gels, zirconium monohydrogen phosphate spherules, hydrous zirconium oxide spherules having suspendable particles homogeneously embedded within to form a composite sorbent, zirconium monohydrogen phosphate spherules having suspendable particles of at least one different sorbent homogeneously embedded within to form a composite sorbent having a desired crystallinity, zirconium oxide spherules having suspendable particles homogeneously embedded within to form a composite, hydrous zirconium oxide fiber materials, zirconium oxide fiber materials, hydrous zirconium oxide fiber materials having suspendable particles homogeneously embedded within to form a composite, zirconium oxide fiber materials having suspendable particles homogeneously embedded within to form a composite and spherules of barium zirconate. The hydrous zirconium oxide spherules and gel forms prepared by the gel-sphere, internal gelation process are useful as inorganic ion exchangers, catalysts, getters and ceramics.

Niobium hyperfine structure in crystal calcium tungstate

NASA Technical Reports Server (NTRS)

Tseng, D. L.; Kikuchi, C.

1972-01-01

A study of the niobium hyperfine structure in single crystal calcium tungstate was made by the combination of the technique of electron paramagnetic resonance and electron nuclear double resonance (EPR/ENDOR). The microwave frequency was about 9.4 GHz and the radio frequency from 20MHz to 70 MHz. The rare earth ions Nd(3+), U(3+), or Tm(3+) were added as the charge compensator for Nb(5+). To create niobium paramagnetic centers, the sample was irradiated at 77 deg K with a 10 thousand curie Co-60 gamma source for 1 to 2 hours at a dose rate of 200 K rads per hour and then transferred quickly into the cavity. In a general direction of magnetic field, the spectra showed 4 sets of 10 main lines corresponding to 4 nonequivalent sites of niobium with I = 9/2. These 4 sets of lines coalesced into 2 sets of 10 in the ab-plane and into a single set of 10 along the c-axis. This symmetry suggested that the tungsten ions are substituted by the niobium ions in the crystal.

SRF MATERIALS OTHER THAN NIOBIUM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valente, Anne-Marie

2008-02-12

For the past three decades, bulk niobium has been the material of choice for SRF cavity applications. Alternative materials, mainly Nb compounds and A15 compounds have been investigated with moderate effort in the past. In the recent years, RF cavity performance has approached the theoretical limit for bulk niobium. For further improvement of RF cavity performance for future accelerator projects, research interest is renewed towards alternative materials to niobium. A few laboratories around the world are now investigating superconductors with higher transition temperature Tc for application to SRF cavities. This paper gives an overview of the results obtained and challengesmore » encountered for Nb compounds and A15 compounds, as well as for MgB2, for SRF cavity applications. An interesting alternative has been recently proposed by Alex Gurevich with the Superconductor-Insulator-Superconductor multilayer approach. This could potentially lead to further improvement in RF cavity performance using the benefit of the higher critical field Hc of higher-Tc superconductors without being limited with their lower Hc1.« less

First-principles calculations of niobium hydride formation in superconducting radio-frequency cavities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ford, Denise C.; Cooley, Lance D.; Seidman, David N.

Niobium hydride is suspected to be a major contributor to degradation of the quality factor of niobium superconducting radio-frequency (SRF) cavities. In this study, we connect the fundamental properties of hydrogen in niobium to SRF cavity performance and processing. We modeled several of the niobium hydride phases relevant to SRF cavities and present their thermodynamic, electronic, and geometric properties determined from calculations based on density-functional theory. We find that the absorption of hydrogen from the gas phase into niobium is exothermic and hydrogen becomes somewhat anionic. The absorption of hydrogen by niobium lattice vacancies is strongly preferred over absorption intomore » interstitial sites. A single vacancy can accommodate six hydrogen atoms in the symmetrically equivalent lowest-energy sites and additional hydrogen in the nearby interstitial sites affected by the strain field: this indicates that a vacancy can serve as a nucleation center for hydride phase formation. Small hydride precipitates may then occur near lattice vacancies upon cooling. Vacancy clusters and extended defects should also be enriched in hydrogen, potentially resulting in extended hydride phase regions upon cooling. We also assess the phase changes in the niobium-hydrogen system based on charge transfer between niobium and hydrogen, the strain field associated with interstitial hydrogen, and the geometry of the hydride phases. The results of this study stress the importance of not only the hydrogen content in niobium, but also the recovery state of niobium for the performance of SRF cavities.« less

Pre-treatment for molybdenum or molybdenum-rich alloy articles to be plated

DOEpatents

Wright, Ralph R.

1980-01-01

This invention is a method for etching a molybdenum or molybdenum-rich alloy surface to promote the formation of an adherent bond with a subsequently deposited metallic plating. In a typical application, the method is used as a pre-treatment for surfaces to be electrolessly plated with nickel. The pre-treatment comprises exposing the crystal boundaries of the surface by (a) anodizing the surface in acidic solution to form a continuous film of gray molybdenum oxide thereon and (b) removing the film.

Fine-grained zirconium-base material

DOEpatents

Van Houten, G.R.

1974-01-01

A method is described for making zirconium with inhibited grain growth characteristics, by the process of vacuum melting the zirconium, adding 0.3 to 0.5% carbon, stirring, homogenizing, and cooling. (Official Gazette)

Mineral resource of the month: molybdenum

USGS Publications Warehouse

Polyak, Désire E.

2011-01-01

The article offers information about the mineral molybdenum. Sources includes byproduct or coproduct copper-molybdenum deposits in the Western Cordillera of North and South America. Among the uses of molybdenum are stainless steel applications, as an alloy material for manufacturing vessels and as lubricants, pigments or chemicals. Also noted is the role played by molybdenum in renewable energy technology.

A niobium oxide-tantalum oxide selector-memristor self-aligned nanostack

NASA Astrophysics Data System (ADS)

Diaz Leon, Juan J.; Norris, Kate J.; Yang, J. Joshua; Sevic, John F.; Kobayashi, Nobuhiko P.

2017-03-01

The integration of nonlinear current-voltage selectors and bi-stable memristors is a paramount step for reliable operation of crossbar arrays. In this paper, the self-aligned assembly of a single nanometer-scale device that contains both a selector and a memristor is presented. The two components (i.e., selector and memristor) are vertically assembled via a self-aligned fabrication process combined with electroforming. In designing the device, niobium oxide and tantalum oxide are chosen as materials for selector and memristor, respectively. The formation of niobium oxide is visualized by exploiting the self-limiting reaction between niobium and tantalum oxide; crystalline niobium (di)oxide forms at the interface between metallic niobium and tantalum oxide via electrothermal heating, resulting in a niobium oxide selector self-aligned to a tantalum oxide memristor. A steady-state finite element analysis is used to assess the electrothermal heating expected to occur in the device. Current-voltage measurements and structural/chemical analyses conducted for the virgin device, the electroforming process, and the functional selector-memristor device are presented. The demonstration of a self-aligned, monolithically integrated selector-memristor device would pave a practical pathway to various circuits based on memristors attainable at manufacturing scales.

SEPARATION OF HAFNIUM FROM ZIRCONIUM

DOEpatents

Overholser, L.B.; Barton, C.J. Sr.; Ramsey, J.W.

1960-05-31

The separation of hafnium impurities from zirconium can be accomplished by means of organic solvent extraction. The hafnium-containing zirconium feed material is dissolved in an aqueous chloride solution and the resulting solution is contacted with an organic hexone phase, with at least one of the phases containing thiocyanate. The hafnium is extracted into the organic phase while zirconium remains in the aqueous phase. Further recovery of zirconium is effected by stripping the onganic phase with a hydrochloric acid solution and commingling the resulting strip solution with the aqueous feed solution. Hexone is recovered and recycled by means of scrubbing the onganic phase with a sulfuric acid solution to remove the hafnium, and thiocyanate is recovered and recycled by means of neutralizing the effluent streams to obtain ammonium thiocyanate.

Zirconium

USGS Publications Warehouse

Bedinger, G.M.

2013-01-01

Zirconium is the 20th most abundant element in the Earth’s crust. It occurs in a variety of rock types and geologic environments but most often in igneous rocks in the form of zircon (ZrSiO4). Zircon is recovered as a coproduct of the mining and processing of heavy mineral sands for the titanium minerals ilmenite and rutile. The sands are formed by the weathering and erosion of rock containing zircon and titanium heavy minerals and their subsequent concentration in sedimentary systems, particularly in coastal environments. A small quantity of zirconium, less than 10 kt/a (11,000 stpy), compared with total world production of 1.4 Mt (1.5 million st) in 2012, was derived from the mineral baddeleyite (ZrO2), produced from a single source in Kovdor, Russia.

Superconducting structure with layers of niobium nitride and aluminum nitride

DOEpatents

Murduck, James M.; Lepetre, Yves J.; Schuller, Ivan K.; Ketterson, John B.

1989-01-01

A superconducting structure is formed by depositing alternate layers of aluminum nitride and niobium nitride on a substrate. Deposition methods include dc magnetron reactive sputtering, rf magnetron reactive sputtering, thin-film diffusion, chemical vapor deposition, and ion-beam deposition. Structures have been built with layers of niobium nitride and aluminum nitride having thicknesses in a range of 20 to 350 Angstroms. Best results have been achieved with films of niobium nitride deposited to a thickness of approximately 70 Angstroms and aluminum nitride deposited to a thickness of approximately 20 Angstroms. Such films of niobium nitride separated by a single layer of aluminum nitride are useful in forming Josephson junctions. Structures of 30 or more alternating layers of niobium nitride and aluminum nitride are useful when deposited on fixed substrates or flexible strips to form bulk superconductors for carrying electric current. They are also adaptable as voltage-controlled microwave energy sources.

Mechanical properties of niobium radio-frequency cavities

DOE PAGES

Ciovati, Gianluigi; Dhakal, Pashupati; Matalevich, Joseph R.; ...

2015-07-02

Radio-frequency cavities made of bulk niobium are one of the components used in modern particle accelerators. The mechanical stability is an important aspect of cavity design, which typically relies on finite-element analysis simulations using material properties from tensile tests on sample. This contribution presents the results of strain and resonant frequency measurements as a function of a uniform pressure up to 722 kPa, applied to single-cell niobium cavities with different crystallographic structure, purity and treatments. In addition, burst tests of high-purity multi-cell cavities with different crystallographic structure have been conducted up to the tensile strength of the material. Finite-element analysismore » of the single-cell cavity geometry is in good agreement with the observed behavior in the elastic regime assuming a Young's modulus value of 88.5 GPa and a Poisson's ratio of 0.4, regardless of crystallographic structure, purity or treatment. However, the measured yield strength and tensile strength depend on crystallographic structure, material purity and treatment. In particular, the results from this study show that the mechanical properties of niobium cavities with large crystals are comparable to those of cavities made of fine-grain niobium.« less

Metallic transfer between metals in sliding contact examined by auger emission spectroscopy

NASA Technical Reports Server (NTRS)

Pepper, S. V.

1972-01-01

Metallic transfer between polycrystalline metals in sliding contact was examined. Hemispherical riders of iron, nickel, and cobalt were slid on tungsten, tantalum, niobium, and molybdenum disks in ultrahigh vacuum. Auger emission spectroscopy was used to monitor the elemental composition of the disk surfaces. Iron, nickel, and cobalt transferred to tungsten, whereas only cobalt transferred to tantalum, niobium, and molybdenum. The results of this investigation are discussed in terms of the cohesive energy and strain hardening characteristics of the specimen materials.

Gel Fabrication of Molybdenum “Beads”

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lowden, Richard Andrew; Armstrong, Beth L.; Cooley, Kevin M.

2016-11-01

Spherical molybdenum particles or “beads” of various diameters are of interest as feedstock materials for the additive manufacture of targets and assemblies used in the production of 99Mo medical isotopes using accelerator technology. Small metallic beads or ball bearings are typically fabricated from wire; however, small molybdenum spheres cannot readily be produced in this manner. Sol-gel processes are often employed to produce small dense microspheres of metal oxides across a broad diameter range that in the case of molybdenum could be reduced and sintered to produce metallic spheres. These Sol-gel type processes were examined for forming molybdenum oxide beads; however,more » the molybdenum trioxide was chemically incompatible with commonly used gelation materials. As an alternative, an aqueous alginate process being assessed for the fabrication of oxide spheres for catalyst applications was employed to form molybdenum trioxide beads that were successfully reduced and sintered to produce small molybdenum spheres.« less

Superconducting structure with layers of niobium nitride and aluminum nitride

DOEpatents

Murduck, J.M.; Lepetre, Y.J.; Schuller, I.K.; Ketterson, J.B.

1989-07-04

A superconducting structure is formed by depositing alternate layers of aluminum nitride and niobium nitride on a substrate. Deposition methods include dc magnetron reactive sputtering, rf magnetron reactive sputtering, thin-film diffusion, chemical vapor deposition, and ion-beam deposition. Structures have been built with layers of niobium nitride and aluminum nitride having thicknesses in a range of 20 to 350 Angstroms. Best results have been achieved with films of niobium nitride deposited to a thickness of approximately 70 Angstroms and aluminum nitride deposited to a thickness of approximately 20 Angstroms. Such films of niobium nitride separated by a single layer of aluminum nitride are useful in forming Josephson junctions. Structures of 30 or more alternating layers of niobium nitride and aluminum nitride are useful when deposited on fixed substrates or flexible strips to form bulk superconductors for carrying electric current. They are also adaptable as voltage-controlled microwave energy sources. 8 figs.

International strategic minerals inventory summary report; niobium (columbium) and tantalum

USGS Publications Warehouse

Crockett, R.N.; Sutphin, D.M.

1993-01-01

Major world resources of niobium and tantalum are described in this summary report of information in the International Strategic Minerals Inventory (ISMI). ISMI is a cooperative data-collection effort of earth-science and mineral-resource agencies in Australia, Canada, the Federal Republic of Germany, the Republic of South Africa, the United Kingdom, and the United States of America. Part I of this report presents an overview of the resources and potential supply of niobium and tantalum based on inventory information; Part II contains tables of both geologic and mineral-resource information and includes production data collected by ISMI participants. Niobium is used principally as an alloying element in special steels and superalloys, and tantalum is used mainly in electronics. Minerals in the columbite-tantalite series are principal ore minerals of niobium and tantalum. Pyrochlore is a principal source of niobium. These minerals are found in carbonatite, certain rocks in alkaline igneous complexes, pegmatite, and placer deposits. ISMI estimates show that there are over 7 million metric tons of niobium and almost 0.5 million metric tons of tantalum in known deposits, outside of China and the former Soviet Union, for which reliable estimates have been made. Brazilian deposits, followed by Canadian deposits, contain by far the largest source of niobium. Tantalum production is spread widely among several countries, and Brazil and Canada are the most significant of these producers. Brazil's position is further strengthened by potential byproduct columbite from tin mining. Present economically exploitable resources of niobium appear to be sufficient for the near future, but Brazil will continue to be the predominant world supplier of ferrocolumbium. Tantalum, a byproduct of tin production, has been captive to the fluctuations of that market, but resources in pegmatite in Canada and Australia make it likely that future increases in the present modest demand will be met.

Molybdenum reduction to molybdenum blue in Serratia sp. Strain DRY5 is catalyzed by a novel molybdenum-reducing enzyme.

PubMed

Shukor, M Y; Halmi, M I E; Rahman, M F A; Shamaan, N A; Syed, M A

2014-01-01

The first purification of the Mo-reducing enzyme from Serratia sp. strain DRY5 that is responsible for molybdenum reduction to molybdenum blue in the bacterium is reported. The monomeric enzyme has an apparent molecular weight of 105 kDalton. The isoelectric point of this enzyme was 7.55. The enzyme has an optimum pH of 6.0 and maximum activity between 25 and 35°C. The Mo-reducing enzyme was extremely sensitive to temperatures above 50°C (between 54 and 70°C). A plot of initial rates against substrate concentrations at 15 mM 12-MP registered a V max for NADH at 12.0 nmole Mo blue/min/mg protein. The apparent K m for NADH was 0.79 mM. At 5 mM NADH, the apparent V max and apparent K m values for 12-MP of 12.05 nmole/min/mg protein and 3.87 mM, respectively, were obtained. The catalytic efficiency (k cat/K m ) of the Mo-reducing enzyme was 5.47 M(-1) s(-1). The purification of this enzyme could probably help to solve the phenomenon of molybdenum reduction to molybdenum blue first reported in 1896 and would be useful for the understanding of the underlying mechanism in molybdenum bioremediation involving bioreduction.

Molybdenum Reduction to Molybdenum Blue in Serratia sp. Strain DRY5 Is Catalyzed by a Novel Molybdenum-Reducing Enzyme

PubMed Central

Shukor, M. Y.; Halmi, M. I. E.; Rahman, M. F. A.; Shamaan, N. A.; Syed, M. A.

2014-01-01

The first purification of the Mo-reducing enzyme from Serratia sp. strain DRY5 that is responsible for molybdenum reduction to molybdenum blue in the bacterium is reported. The monomeric enzyme has an apparent molecular weight of 105 kDalton. The isoelectric point of this enzyme was 7.55. The enzyme has an optimum pH of 6.0 and maximum activity between 25 and 35°C. The Mo-reducing enzyme was extremely sensitive to temperatures above 50°C (between 54 and 70°C). A plot of initial rates against substrate concentrations at 15 mM 12-MP registered a V max for NADH at 12.0 nmole Mo blue/min/mg protein. The apparent K m for NADH was 0.79 mM. At 5 mM NADH, the apparent V max and apparent K m values for 12-MP of 12.05 nmole/min/mg protein and 3.87 mM, respectively, were obtained. The catalytic efficiency (k cat/K m) of the Mo-reducing enzyme was 5.47 M−1 s−1. The purification of this enzyme could probably help to solve the phenomenon of molybdenum reduction to molybdenum blue first reported in 1896 and would be useful for the understanding of the underlying mechanism in molybdenum bioremediation involving bioreduction. PMID:24724104

Surface processing for bulk niobium superconducting radio frequency cavities

NASA Astrophysics Data System (ADS)

Kelly, M. P.; Reid, T.

2017-04-01

The majority of niobium cavities for superconducting particle accelerators continue to be fabricated from thin-walled (2-4 mm) polycrystalline niobium sheet and, as a final step, require material removal from the radio frequency (RF) surface in order to achieve performance needed for use as practical accelerator devices. More recently bulk niobium in the form of, single- or large-grain slices cut from an ingot has become a viable alternative for some cavity types. In both cases the so-called damaged layer must be chemically etched or electrochemically polished away. The methods for doing this date back at least four decades, however, vigorous empirical studies on real cavities and more fundamental studies on niobium samples at laboratories worldwide have led to seemingly modest improvements that, when taken together, constitute a substantial advance in the reproducibility for surface processing techniques and overall cavity performance. This article reviews the development of niobium cavity surface processing, and summarizes results of recent studies. We place some emphasis on practical details for real cavity processing systems which are difficult to find in the literature but are, nonetheless, crucial for achieving the good and reproducible cavity performance. New approaches for bulk niobium surface treatment which aim to reduce cost or increase performance, including alternate chemical recipes, barrel polishing and ‘nitrogen doping’ of the RF surface, continue to be pursued and are closely linked to the requirements for surface processing.

Surface processing for bulk niobium superconducting radio frequency cavities

DOE PAGES

Kelly, M. P.; Reid, T.

2017-02-21

The majority of niobium cavities for superconducting particle accelerators continue to be fabricated from thin-walled (2-4mm) polycrystalline niobium sheet and, as a final step, require material removal from the radio frequency (RF) surface in order to achieve performance needed for use as practical accelerator devices. More recently bulk niobium in the form of, single-or large-grain slices cut from an ingot has become a viable alternative for some cavity types. In both cases the so-called damaged layer must be chemically etched or electrochemically polished away. The methods for doing this date back at least four decades, however, vigorous empirical studies onmore » real cavities and more fundamental studies on niobium samples at laboratories worldwide have led to seemingly modest improvements that, when taken together, constitute a substantial advance in the reproducibility for surface processing techniques and overall cavity performance. This article reviews the development of niobium cavity surface processing, and summarizes results of recent studies. We place some emphasis on practical details for real cavity processing systems which are difficult to find in the literature but are, nonetheless, crucial for achieving the good and reproducible cavity performance. New approaches for bulk niobium surface treatment which aim to reduce cost or increase performance, including alternate chemical recipes, barrel polishing and 'nitrogen doping' of the RF surface, continue to be pursued and are closely linked to the requirements for surface processing.« less

Surface processing for bulk niobium superconducting radio frequency cavities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kelly, M. P.; Reid, T.

The majority of niobium cavities for superconducting particle accelerators continue to be fabricated from thin-walled (2-4mm) polycrystalline niobium sheet and, as a final step, require material removal from the radio frequency (RF) surface in order to achieve performance needed for use as practical accelerator devices. More recently bulk niobium in the form of, single-or large-grain slices cut from an ingot has become a viable alternative for some cavity types. In both cases the so-called damaged layer must be chemically etched or electrochemically polished away. The methods for doing this date back at least four decades, however, vigorous empirical studies onmore » real cavities and more fundamental studies on niobium samples at laboratories worldwide have led to seemingly modest improvements that, when taken together, constitute a substantial advance in the reproducibility for surface processing techniques and overall cavity performance. This article reviews the development of niobium cavity surface processing, and summarizes results of recent studies. We place some emphasis on practical details for real cavity processing systems which are difficult to find in the literature but are, nonetheless, crucial for achieving the good and reproducible cavity performance. New approaches for bulk niobium surface treatment which aim to reduce cost or increase performance, including alternate chemical recipes, barrel polishing and 'nitrogen doping' of the RF surface, continue to be pursued and are closely linked to the requirements for surface processing.« less

40 CFR 721.9973 - Zirconium dichlorides (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Zirconium dichlorides (generic). 721... Substances § 721.9973 Zirconium dichlorides (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as zirconium dichlorides (PMNs P...

Genetics Home Reference: molybdenum cofactor deficiency

MedlinePlus

... called molybdenum cofactor. Molybdenum cofactor, which contains the element molybdenum, is essential to the function of several ... Citation on PubMed or Free article on PubMed Central Reiss J, Gross-Hardt S, Christensen E, Schmidt P, ...

Method of producing molybdenum-99

DOEpatents

Pitcher, Eric John

2013-05-28

Method of producing molybdenum-99, comprising accelerating ions by means of an accelerator; directing the ions onto a metal target so as to generate neutrons having an energy of greater than 10 MeV; directing the neutrons through a converter material comprising techentium-99 to produce a mixture comprising molybdenum-99; and, chemically extracting the molybdenum-99 from the mixture.

Determination of niobium in rocks by an isotope dilution spectrophotometric method

USGS Publications Warehouse

Greenland, L.P.; Campbell, E.Y.

1970-01-01

Rocks and minerals are fused with sodium peroxide in the presence of carrierfree 95Nb. The fusion cake is leached with water and the precipitate dissolved in hydrofluoric-sulfuric acid mixture. Niobium is extracted into methyl isobutyl ketone and further purified by ion exchange. The amount of niobium is determined spectrophotometrically with 4-(2-pyridylazo)-resorcinol, and the chemical yield of the separations determined by counting 95Nb. This procedure is faster and less sensitive to interferences than previously proposed methods for determining niobium in rocks.The high purity of the separated niobium makes the method applicable to nearly all matrices. ?? 1970.

Crystallography and Morphology of Niobium Carbide in As-Cast HP-Niobium Reformer Tubes

NASA Astrophysics Data System (ADS)

Buchanan, Karl G.; Kral, Milo V.

2012-06-01

The microstructures of two as-cast heats of niobium-modified HP stainless steels were characterized. Particular attention was paid to the interdendritic niobium-rich carbides formed during solidification of these alloys. At low magnifications, these precipitates are grouped in colonies of similar lamellae. Higher magnifications revealed that the lamellae actually obtain two distinct morphologies. The type I morphology exhibits broad planar interfaces with a smooth platelike shape. Type II lamellae have undulating interfaces and an overall reticulated shape. To provide further insight into the origin of these two different morphologies, the microstructure and crystallography of each have been studied in detail using high resolution scanning electron microscopy, transmission electron microscopy, various electron diffraction methods (electron backscatter diffraction (EBSD), selected area diffraction (SAD), and convergent beam electron diffraction (CBED)), and energy dispersive X-ray spectroscopy.

Nonresonant valence-to-core x-ray emission spectroscopy of niobium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ravel, Bruce; Kropf, A. Jeremy; Yang, Dali

The valence-to-core (V2C) portion of x-ray emission spectroscopy (XES) measures the electron states close to the Fermi level. These states are involved in bonding, thus providing a measure of the chemistry of the material. For this paper, we show the V2C XES spectra for several niobium compounds. The Kβ" peak in the V2C XES results from the transition of a ligand 2s electron into the 1s core-hole of the niobium, a transition allowed by hybridization with the niobium 4p . This location in energy of this weak peak shows a strong ligand dependence, thus providing a sensitive probe of themore » ligand environment about the niobium.« less

Nonresonant valence-to-core x-ray emission spectroscopy of niobium

DOE PAGES

Ravel, Bruce; Kropf, A. Jeremy; Yang, Dali; ...

2018-03-23

The valence-to-core (V2C) portion of x-ray emission spectroscopy (XES) measures the electron states close to the Fermi level. These states are involved in bonding, thus providing a measure of the chemistry of the material. For this paper, we show the V2C XES spectra for several niobium compounds. The Kβ" peak in the V2C XES results from the transition of a ligand 2s electron into the 1s core-hole of the niobium, a transition allowed by hybridization with the niobium 4p . This location in energy of this weak peak shows a strong ligand dependence, thus providing a sensitive probe of themore » ligand environment about the niobium.« less

Mineral resource of the month: niobium (columbium)

USGS Publications Warehouse

Papp, John F.

2007-01-01

It’s not just diamonds associated with conflict in Africa. Coltan, short for columbite-tantalite (a blend of niobium — also called columbium — and tantalum minerals), is linked with the recent conflicts in the Congo that involved several African countries. The metallic ore, which is processed to separate out niobium and the very valuable tantalum (see Geotimes, August 2004), is believed to be smuggled out and sold to help finance the armed conflicts.

Oxidized zirconium on ceramic; Catastrophic coupling.

PubMed

Ozden, V E; Saglam, N; Dikmen, G; Tozun, I R

2017-02-01

Oxidized zirconium (Oxinium™; Smith & Nephew, Memphis, TN, USA) articulated with polyethylene in total hip arthroplasty (THA) appeared to have the potential to reduce wear dramatically. The thermally oxidized metal zirconium surface is transformed into ceramic-like hard surface that is resistant to abrasion. The exposure of soft zirconium metal under hard coverage surface after the damage of oxidized zirconium femoral head has been described. It occurred following joint dislocation or in situ succeeding disengagement of polyethylene liner. We reported three cases of misuse of Oxinium™ (Smith & Nephew, Memphis, TN, USA) heads. These three cases resulted in catastrophic in situ wear and inevitable failure although there was no advice, indication or recommendation for this use from the manufacturer. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Zirconium behaviour during electrorefining of actinide-zirconium alloy in molten LiCl-KCl on aluminium cathodes

NASA Astrophysics Data System (ADS)

Meier, R.; Souček, P.; Malmbeck, R.; Krachler, M.; Rodrigues, A.; Claux, B.; Glatz, J.-P.; Fanghänel, Th.

2016-04-01

A pyrochemical electrorefining process for the recovery of actinides from metallic nuclear fuel based on actinide-zirconium alloys (An-Zr) in a molten salt is being investigated. In this process actinides are group-selectively recovered on solid aluminium cathodes as An-Al alloys using a LiCl-KCl eutectic melt at a temperature of 450 °C. In the present study the electrochemical behaviour of zirconium during electrorefining was investigated. The maximum amount of actinides that can be oxidised without anodic co-dissolution of zirconium was determined at a selected constant cathodic current density. The experiment consisted of three steps to assess the different stages of the electrorefining process, each of which employing a fresh aluminium cathode. The results indicate that almost a complete dissolution of the actinides without co-dissolution of zirconium is possible under the applied experimental conditions.

Molybdenum Oxides - From Fundamentals to Functionality.

PubMed

de Castro, Isabela Alves; Datta, Robi Shankar; Ou, Jian Zhen; Castellanos-Gomez, Andres; Sriram, Sharath; Daeneke, Torben; Kalantar-Zadeh, Kourosh

2017-10-01

The properties and applications of molybdenum oxides are reviewed in depth. Molybdenum is found in various oxide stoichiometries, which have been employed for different high-value research and commercial applications. The great chemical and physical characteristics of molybdenum oxides make them versatile and highly tunable for incorporation in optical, electronic, catalytic, bio, and energy systems. Variations in the oxidation states allow manipulation of the crystal structure, morphology, oxygen vacancies, and dopants, to control and engineer electronic states. Despite this overwhelming functionality and potential, a definitive resource on molybdenum oxide is still unavailable. The aim here is to provide such a resource, while presenting an insightful outlook into future prospective applications for molybdenum oxides. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of copper sulfate supplement on growth, tissue concentration, and ruminal solubilities of molybdenum and copper in sheep fed low and high molybdenum diets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ivan, M.; Veira, D.M.

1985-01-01

Each of four groups of six wethers were fed one of a low molybdenum, high molybdenum, high molybdenum plus copper sulfate, or high molybdenum plus copper sulfate corn silage-based diet for ad libitum intake for 221 days. Average daily gains and ratios of feed/gain were depressed for the high molybdenum diet as compared with the low molybdenum diet suggesting molybdenum toxicity in sheep fed the high molybdenum diet. This was alleviated partly by the copper sulfate supplement. The supplement also decreased solubility of both copper and molybdenum in the rumen but had no effect on copper concentration in blood plasma.more » Concentration of molybdenum was higher in both liver and kidney in sheep fed high-molybdenum diets as compared with low-molybdenum diets. Copper concentration was higher in kidneys of sheep fed high-molybdenum diets, but no difference was significant in liver copper between sheep fed diets high or low in molybdenum.« less

Physical characterization of a new composition of oxidized zirconium-2.5 wt% niobium produced using a two step process for biomedical applications

NASA Astrophysics Data System (ADS)

Pawar, V.; Weaver, C.; Jani, S.

2011-05-01

Zirconium and particularly Zr-2.5 wt%Nb (Zr2.5Nb) alloy are useful for engineering bearing applications because they can be oxidized in air to form a hard surface ceramic. Oxidized zirconium (OxZr) due to its abrasion resistant ceramic surface and biocompatible substrate alloy has been used as a bearing surface in total joint arthroplasty for several years. OxZr is characterized by hard zirconium oxide (oxide) formed on Zr2.5Nb using one step thermal oxidation carried out in air. Because the oxide is only at the surface, the bulk material behaves like a metal, with high toughness. The oxide, furthermore, exhibits high adhesion to the substrate because of an oxygen-rich diffusion hardened zone (DHZ) interposing between the oxide and the substrate. In this study, we demonstrate a two step process that forms a thicker DHZ and thus increased depth of hardening than that can be obtained using a one step oxidation process. The first step is thermal oxidation in air and the second step is a heat treatment in vacuum. The second step drives oxygen from the oxide formed in the first step deeper into the substrate to form a thicker DHZ. During the process only a portion of the oxide is dissolved. This new composition (DHOxZr) has approximately 4-6 μm oxide similar to that of OxZr. The nano-hardness of the oxide is similar but the DHZ is approximately 10 times thicker. The stoichiometry of the oxide is similar and a secondary phase rich in oxygen is present through the entire thickness. Due to the increased depth of hardening, the critical load required for the onset of oxide cracking is approximately 1.6 times more than that of the oxide of OxZr. This new composition has a potential to be used as a bearing surface in applications where greater depth of hardening is required.

First-Principles Study of Carbon and Vacancy Structures in Niobium

DOE PAGES

Ford, Denise C.; Zapol, Peter; Cooley, Lance D.

2015-04-03

The interstitial chemical impurities hydrogen, oxygen, nitrogen, and carbon are important for niobium metal production, and particularly for the optimization of niobium SRF technology. These atoms are present in refined sheets and can be absorbed into niobium during processing treatments, resulting in changes to the residual resistance and the performance of SRF cavities. A first-principles approach is taken to study the properties of carbon in niobium, and the results are compared and contrasted with the properties of the other interstitial impurities. The results indicate that C will likely form precipitates or atmospheres around defects rather than strongly bound complexes withmore » other impurities. Based on the analysis of carbon and hydrogen near niobium lattice vacancies and small vacancy chains and clusters, the formation of extended carbon chains and hydrocarbons is not likely to occur. Association of carbon with hydrogen atoms can, however, occur through the strain fields created by interstitial binding of the impurity atoms. In conclusion, calculated electronic densities of states indicate that interstitial C may have a similar effect as interstitial O on the superconducting transition temperature of Nb.« less

Synthesis, characterization, and catalytic application of ordered mesoporous carbon–niobium oxide composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Juan-Li; Gao, Shuang; Liu, Chun-Ling

2014-11-15

Graphical abstract: The ordered mesoporous carbon–niobium oxide composites have been synthesized by a multi-component co-assembly method associated with a carbonization process. - Highlights: • Ordered mesoporous carbon–niobium oxide composites were synthesized. • The content of Nb{sub 2}O{sub 5} in the composites could be tuned from 38 to 75%. • Niobium species were highly dispersed in amorphous carbon framework walls. • The composites exhibited good catalytic performance in the dehydration of fructose. - Abstract: Ordered mesoporous carbon–niobium oxide composites have been synthesized by a multi-component co-assembly method associated with a carbonization process using phenolic resol as carbon source, niobium chloride asmore » precursor and amphiphilic triblock copolymer Pluronic F127 as template. The resulting materials were characterized using a combination of techniques including differential scanning calorimetry–thermogravimetric analysis, N{sub 2} physical adsorption, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The results show that with increasing the content of Nb{sub 2}O{sub 5} from 38 to 75% the specific surface area decreases from 306.4 to 124.5 m{sup 2} g{sup −1}, while the ordered mesoporous structure is remained. Niobium species is well dispersed in the amorphous carbon framework. The mesoporous carbon–niobium oxide composites exhibit high catalytic activity in the dehydration of fructose to 5-hydroxymethylfurfural. A 100% conversion of fructose and a 76.5% selectivity of 5-hydroxymethylfurfural were obtained over the carbon–niobium oxide composite containing 75% Nb{sub 2}O{sub 5} under the investigated reaction conditions.« less

Molybdenum compounds in organic synthesis

NASA Astrophysics Data System (ADS)

Khusnutdinov, R. I.; Oshnyakova, T. M.; Dzhemilev, U. M.

2017-02-01

The review presents the first analysis and systematic discussion of data published in the last 35-40 years on the use of molybdenum compounds and complexes in organic synthesis and catalysis of various ion coordination and radical reactions. Detailed account is given of the key trends in the use of molybdenum complexes as catalysts of alkene epoxidation and oxyketonation, oxidation of sulfur, nitrogen and phosphorus compounds, hydrosilylation of 1,3-dienes, ketones and aldehydes, hydrostannylation of acetylenes and hydrogermylation of norbornadienes. Considerable attention is paid to the description of new reactions and in situ generation of highly reactive hypohalites, ROX and HOX, induced by molybdenum complexes and the use of hypohalites in oxidative transformations. Data on the application of molybdenum complexes in well-known reactions are discussed, including Kharasch and Pauson-Khand reactions, allylic alkylation of C-nucleophiles, aminocarbonylation of halo derivatives and oligomerization of cyclic dienes, trienes, alkynes and 1,3-dienes. The last Section of the review considers 'unusual' organic reactions involving molybdenum compounds and complexes. The bibliography includes 257 references.

Structural phase transitions in niobium oxide nanocrystals

NASA Astrophysics Data System (ADS)

Yuvakkumar, R.; Hong, Sun Ig

2015-09-01

Niobium oxide nanocrystals were successfully synthesized employing the green synthesis method. Phase formation, microstructure and compositional properties of 1, 4 and 7 days incubation treated samples after calcinations at 450 °C were examined using X-ray diffraction, Raman, photoluminescence (PL), infrared, X-ray photoelectron spectra and transmission electron microscopic characterizations. It was observed that phase formation of Nb2O5 nanocrystals was dependent upon the incubation period required to form stable metal oxides. The characteristic results clearly revealed that with increasing incubation and aging, the transformation of cubic, orthorhombic and monoclinic phases were observed. The uniform heating at room temperature (32 °C) and the ligation of niobium atoms due to higher phenolic constituents of utilized rambutan during aging processing plays a vital role in structural phase transitions in niobium oxide nanocrystals. The defects over a period of incubation and the intensities of the PL spectra changing over a period of aging were related to the amount of the defects induced by the phase transition.

Molybdenum disilicide matrix composite

DOEpatents

Petrovic, John J.; Carter, David H.; Gac, Frank D.

1991-01-01

A composition consisting of an intermetallic compound, molybdenum disilicide, which is reinforced with VS silicon carbide whiskers dispersed throughout it and a method of making the reinforced composition. Use of the reinforcing material increases fracture toughness at low temperatures and strength at high temperatures, as compared to pure molybdenum disilicide.

Molybdenum disilicide matrix composite

DOEpatents

Petrovic, John J.; Carter, David H.; Gac, Frank D.

1990-01-01

A composition consisting of an intermetallic compound, molybdenum disilicide, which is reinforced with VS silicon carbide whiskers dispersed throughout it and a method of making the reinforced composition. Use of the reinforcing material increases fracture toughness at low temperatures and strength at high temperatures, as compared to pure molybdenum disilicide.

Processing of Niobium-Lined M240 Machine Gun Barrels

DTIC Science & Technology

2014-11-01

different materials (the gun steel and the niobium liner). A large chunk of the niobium liner in barrel 2 was torn away from the end of the liner at...it to increase the frictional bond between the liner and gun steel . The barrels with liners were hammer forged by FN. FN experienced some...

Deformation and recrystallization behavior of super high-purity niobium for SRF cavity

NASA Astrophysics Data System (ADS)

Yamaguchi, Y.; Doryo, H.; Yuasa, M.; Miyamoto, H.; Yamanaka, M.

2017-05-01

Deformation and recyrstallization behavior of pure niobium was investigated in order to clarify the origin of its low hydro-formability despite of its high ductility comparable with pure iron. It was found that pure niobium exhibits lower strain hardening in cold rolling compared with pure iron. Furthermore, in post-deformation annealing, the hardness of niobium decreased monotonously with an increase of temperature, and the typical sharp drop by recrystallization was not evident. This softening behavior was contrasted with the high-purity iron. It is suggested that niobium exhibit the so-called in-situ recrystallization possibly because of low elastic modulus and low accumulative plastic strain energy in spite of high melting temperature. The low hydro-formability of pure niobium sheets or tubes is caused by its low strain hardening and its unique plastic anisotropy which is associated with this recovered residual rolled texture.

Separation of Zirconium and Hafnium: A Review

NASA Astrophysics Data System (ADS)

Xu, L.; Xiao, Y.; van Sandwijk, A.; Xu, Q.; Yang, Y.

Zirconium is an ideal material for nuclear reactors due to its low absorption cross-section for thermal neutrons, whereas the typically contained hafnium with strong neutron-absorption is very harmful for zirconium. This paper provides an overview of the processes for separating hafnium from zirconium. The separation processes are roughly classified into hydro- and pyrometallurgical routes. The current dominant zirconium production route involves pyrometallurgical ore cracking, multi-step hydrometallurgical liquid-liquid extraction for hafnium removal and the reduction of zirconium tetrachloride to the pure metal by the Kroll process. The lengthy hydrometallurgical Zr-Hf separation operations leads to high production cost, intensive labour and heavy environmental burden. Using a compact pyrometallurgical separation method can simplify the whole production flowsheet with a higher process efficiency. The known separation methods are discussed based on the following reaction features: redox characteristics, volatility, electrochemical properties and molten salt extraction. The commercially operating extractive distillation process is a significant advance in Zr-Hf separation technology but it suffers from high process maintenance cost. The recently developed new process based on molten salt-metal equilibrium for Zr-Hf separation shows a great potential for industrial application, which is compact for nuclear grade zirconium production starting from crude ore. In the present paper, the available separation technologies are compared. The advantages and disadvantages as well as future directions of research and development for nuclear grade zirconium production are discussed.

SEPARATING HAFNIUM FROM ZIRCONIUM

DOEpatents

Lister, B.A.J.; Duncan, J.F.

1956-08-21

A dilute aqueous solution of zirconyl chloride which is 1N to 2N in HCl is passed through a column of a cation exchange resin in acid form thereby absorbing both zirconium and associated hafnium impurity in the mesin. The cation exchange material with the absorbate is then eluted with aqueous sulfuric acid of a O.8N to 1.2N strength. The first portion of the eluate contains the zirconium substantially free of hafnium.

Kinetics of molybdenum reduction to molybdenum blue by Bacillus sp. strain A.rzi.

PubMed

Othman, A R; Bakar, N A; Halmi, M I E; Johari, W L W; Ahmad, S A; Jirangon, H; Syed, M A; Shukor, M Y

2013-01-01

Molybdenum is very toxic to agricultural animals. Mo-reducing bacterium can be used to immobilize soluble molybdenum to insoluble forms, reducing its toxicity in the process. In this work the isolation of a novel molybdate-reducing Gram positive bacterium tentatively identified as Bacillus sp. strain A.rzi from a metal-contaminated soil is reported. The cellular reduction of molybdate to molybdenum blue occurred optimally at 4 mM phosphate, using 1% (w/v) glucose, 50 mM molybdate, between 28 and 30 °C and at pH 7.3. The spectrum of the Mo-blue product showed a maximum peak at 865 nm and a shoulder at 700 nm. Inhibitors of bacterial electron transport system (ETS) such as rotenone, sodium azide, antimycin A, and potassium cyanide could not inhibit the molybdenum-reducing activity. At 0.1 mM, mercury, copper, cadmium, arsenic, lead, chromium, cobalt, and zinc showed strong inhibition on molybdate reduction by crude enzyme. The best model that fitted the experimental data well was Luong followed by Haldane and Monod. The calculated value for Luong's constants p max, K(s), S(m), and n was 5.88 μmole Mo-blue hr(-1), 70.36 mM, 108.22 mM, and 0.74, respectively. The characteristics of this bacterium make it an ideal tool for bioremediation of molybdenum pollution.

Copper-acrylic enamel serves as lubricant for cold drawing of refractory metals

NASA Technical Reports Server (NTRS)

Beane, C.; Karasek, F.

1966-01-01

Acrylic enamel spray containing metallic copper pigment lubricates refractory metal tubing during cold drawing operations so that the tubing surface remains free from scratches and nicks and does not seize in the die. Zirconium alloys, zirconium, tantalum alloys, niobium alloys, vanandium alloys and titanium alloys have been drawn using this lubricant.

SRF niobium characterization using SIMS and FIB-TEM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stevie, F. A.

2015-12-04

Our understanding of superconducting radio frequency (SRF) accelerator cavities has been improved by elemental analysis at high depth resolution and by high magnification microscopy. This paper summarizes the technique development and the results obtained on poly-crystalline, large grain, and single crystal SRF niobium. Focused ion beam made possible sample preparation using transmission electron microscopy and the images obtained showed a very uniform oxide layer for all samples analyzed. Secondary ion mass spectrometry indicated the presence of a high concentration of hydrogen and the hydrogen content exhibited a relationship with improvement in performance. Depth profiles of carbon, nitrogen, and oxygen didmore » not show major differences with heat treatment. Niobium oxide less than 10 nm thick was shown to be an effective hydrogen barrier. Niobium with titanium contamination showed unexpected performance improvement.« less

URANIUM DECONTAMINATION WITH RESPECT TO ZIRCONIUM

DOEpatents

Vogler, S.; Beederman, M.

1961-05-01

A process is given for separating uranium values from a nitric acid aqueous solution containing uranyl values, zirconium values and tetravalent plutonium values. The process comprises contacting said solution with a substantially water-immiscible liquid organic solvent containing alkyl phosphate, separating an organic extract phase containing the uranium, zirconium, and tetravalent plutonium values from an aqueous raffinate, contacting said organic extract phase with an aqueous solution 2M to 7M in nitric acid and also containing an oxalate ion-containing substance, and separating a uranium- containing organic raffinate from aqueous zirconium- and plutonium-containing extract phase.

Carbide and carbonitride surface treatment method for refractory metals

DOEpatents

Meyer, G.A.; Schildbach, M.A.

1996-12-03

A carbide and carbonitride surface treatment method for refractory metals is provided, in steps including, heating a part formed of boron, chromium, hafnium, molybdenum, niobium, tantalum, titanium, tungsten or zirconium, or alloys thereof, in an evacuated chamber and then introducing reaction gases including nitrogen and hydrogen, either in elemental or water vapor form, which react with a source of elemental carbon to form carbon-containing gaseous reactants which then react with the metal part to form the desired surface layer. Apparatus for practicing the method is also provided, in the form of a carbide and carbonitride surface treatment system including a reaction chamber, a source of elemental carbon, a heating subassembly and a source of reaction gases. Alternative methods of providing the elemental carbon and the reaction gases are provided, as well as methods of supporting the metal part, evacuating the chamber with a vacuum subassembly and heating all of the components to the desired temperature. 5 figs.

Feasibility of EB Welded Hastelloy X and Combination of Refractory Metals

NASA Technical Reports Server (NTRS)

Martinez, Diana A.

2004-01-01

As NASA continues to expand its horizon, exploration and discovery creates the need of advancement in technology. The Jupiter Icy Moon Orbiter's (JIMO) mission to explore and document the outer surfaces, rate the possibility of holding potential life forms, etc. within the three moons (Callisto, Ganymede, and Europa) proves to be challenging. The orbiter itself consists of many sections including: the nuclear reactor and the power conversion system, the radiator panels, and the thrusters and antenna. The nuclear reactor serves as a power source, and if successfully developed, can operate for extended periods. During the duration of my tenure at NASA Glenn Research Center's (NASA GRC) Advanced Metallics Branch, I was assigned to assist Frank J. Ritzert on analyzing the feasibility of the Electron Beam Welded Hastelloy X (HX), a nickel-based superalloy, to Niobium- 1 %Zirconium (Nb-1 Zr) and other refractory metals/alloys including Tantalum, Molybdenum, Tungsten, and Rhenium alloys. This welding technique is going to be used for the nuclear reactor within JIMO.

Radioactivity measurements of ITER materials using the TFTR D-T neutron field

NASA Astrophysics Data System (ADS)

Kumar, A.; Abdou, M. A.; Barnes, C. W.; Kugel, H. W.

1994-06-01

The availability of high D-T fusion neutron yields at TFTR has provided a useful opportunity to directly measure D-T neutron-induced radioactivity in a realistic tokamak fusion reactor environment for materials of vital interest to ITER. These measurements are valuable for characterizing radioactivity in various ITER candidate materials, for validating complex neutron transport calculations, and for meeting fusion reactor licensing requirements. The radioactivity measurements at TFTR involve potential ITER materials including stainless steel 316, vanadium, titanium, chromium, silicon, iron, cobalt, nickel, molybdenum, aluminum, copper, zinc, zirconium, niobium, and tungsten. Small samples of these materials were irradiated close to the plasma and just outside the vacuum vessel wall of TFTR, locations of different neutron energy spectra. Saturation activities for both threshold and capture reactions were measured. Data from dosimetric reactions have been used to obtain preliminary neutron energy spectra. Spectra from the first wall were compared to calculations from ITER and to measurements from accelerator-based tests.

Carbide and carbonitride surface treatment method for refractory metals

DOEpatents

Meyer, Glenn A.; Schildbach, Marcus A.

1996-01-01

A carbide and carbonitride surface treatment method for refractory metals is provided, in steps including, heating a part formed of boron, chromium, hafnium, molybdenum, niobium, tantalum, titanium, tungsten or zirconium, or alloys thereof, in an evacuated chamber and then introducing reaction gases including nitrogen and hydrogen, either in elemental or water vapor form, which react with a source of elemental carbon to form carbon-containing gaseous reactants which then react with the metal part to form the desired surface layer. Apparatus for practicing the method is also provided, in the form of a carbide and carbonitride surface treatment system (10) including a reaction chamber (14), a source of elemental carbon (17), a heating subassembly (20) and a source of reaction gases (23). Alternative methods of providing the elemental carbon (17) and the reaction gases (23) are provided, as well as methods of supporting the metal part (12), evacuating the chamber (14) with a vacuum subassembly (18) and heating all of the components to the desired temperature.

Non-noble metal based electro-catalyst compositions for proton exchange membrane based water electrolysis and methods of making

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumta, Prashant N.; Kadakia, Karan Sandeep; Datta, Moni Kanchan

The invention provides electro-catalyst compositions for an anode electrode of a proton exchange membrane-based water electrolysis system. The compositions include a noble metal component selected from the group consisting of iridium oxide, ruthenium oxide, rhenium oxide and mixtures thereof, and a non-noble metal component selected from the group consisting of tantalum oxide, tin oxide, niobium oxide, titanium oxide, tungsten oxide, molybdenum oxide, yttrium oxide, scandium oxide, cooper oxide, zirconium oxide, nickel oxide and mixtures thereof. Further, the non-noble metal component can include a dopant. The dopant can be at least one element selected from Groups III, V, VI and VIImore » of the Periodic Table. The compositions can be prepared using a surfactant approach or a sol gel approach. Further, the compositions are prepared using noble metal and non-noble metal precursors. Furthermore, a thin film containing the compositions can be deposited onto a substrate to form the anode electrode.« less

Nanocomposite anode materials for sodium-ion batteries

DOEpatents

Manthiram, Arumugam; Kim Il, Tae; Allcorn, Eric

2016-06-14

The disclosure relates to an anode material for a sodium-ion battery having the general formula AO.sub.x--C or AC.sub.x--C, where A is aluminum (Al), magnesium (Mg), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), zirconium (Zr), molybdenum (Mo), tungsten (W), niobium (Nb), tantalum (Ta), silicon (Si), or any combinations thereof. The anode material also contains an electrochemically active nanoparticles within the matrix. The nanoparticle may react with sodium ion (Na.sup.+) when placed in the anode of a sodium-ion battery. In more specific embodiments, the anode material may have the general formula M.sub.ySb-M'O.sub.x--C, Sb-MO.sub.x--C, M.sub.ySn-M'C.sub.x--C, or Sn-MC.sub.x--C. The disclosure also relates to rechargeable sodium-ion batteries containing these materials and methods of making these materials.

Thermoinduced laser-assisted deposition of molybdenum from aqueous solutions

NASA Astrophysics Data System (ADS)

Kochemirovsky, Vladimir V.; Logunov, Lev S.; Zhigley, Elvira S.; Baranauskaite, Valeriia

2015-05-01

Local molybdenum deposit obtainment is promising for micro thermocouples creation on dielectric surfaces. This paper is dedicated to development of method of laser-induced molybdenum deposition from water-based solution of inorganic salt on Sitall st-50 and glass dielectric substrates, as well as research of solution composition, pH and substrate optical properties influence on result of laser-induced molybdenum deposition from solution. It was shown that depending on dielectric substrate type, as a result of laser-induced deposition metallic molybdenum or molybdenum dioxide deposit forms: molybdenum dioxide deposits in case of optically clear substrate and metallic molybdenum deposits in case of opaque glass-ceramics. While modelling interim case via using clouded glass, mixture of molybdenum and its oxide was successfully obtained.

Annealed CVD molybdenum thin film surface

DOEpatents

Carver, Gary E.; Seraphin, Bernhard O.

1984-01-01

Molybdenum thin films deposited by pyrolytic decomposition of Mo(CO).sub.6 attain, after anneal in a reducing atmosphere at temperatures greater than 700.degree. C., infrared reflectance values greater than reflectance of supersmooth bulk molybdenum. Black molybdenum films deposited under oxidizing conditions and annealed, when covered with an anti-reflecting coating, approach the ideal solar collector characteristic of visible light absorber and infrared energy reflector.

Studies of Niobium Thin Film Produced by Energetic Vacuum Deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Genfa Wu; Anne-Marie Valente; H. Phillips

2004-05-01

An energetic vacuum deposition system has been used to study deposition energy effects on the properties of niobium thin films on copper and sapphire substrates. The absence of working gas avoids the gaseous inclusions commonly seen with sputtering deposition. A biased substrate holder controls the deposition energy. Transition temperature and residual resistivity ratio of the niobium thin films at several deposition energies are obtained together with surface morphology and crystal orientation measurements by AFM inspection, XRD and TEM analysis. The results show that niobium thin films on sapphire substrate exhibit the best cryogenic properties at deposition energy around 123 eV.more » The TEM analysis revealed that epitaxial growth of film was evident when deposition energy reaches 163 eV for sapphire substrate. Similarly, niobium thin film on copper substrate shows that film grows more oriented with higher deposition energy and grain size reaches the scale of the film thickness at the deposition energy around 153 eV.« less

Process for the generation of .alpha., .beta.-unsaturated carboxylic acids and esters using niobium catalyst

DOEpatents

Gogate, Makarand Ratnakav; Spivey, James Jerome; Zoeller, Joseph Robert

1999-01-01

A process using a niobium catalyst includes the step of reacting an ester or carboxylic acid with oxygen and an alcohol in the presence a niobium catalyst to respectively produce an .alpha.,.beta.-unsaturated ester or carboxylic acid. Methanol may be used as the alcohol, and the ester or carboxylic acid may be passed over the niobium catalyst in a vapor stream containing oxygen and methanol. Alternatively, the process using a niobium catalyst may involve the step of reacting an ester and oxygen in the presence the niobium catalyst to produce an .alpha.,.beta.-unsaturated carboxylic acid. In this case the ester may be a methyl ester. In either case, niobium oxide may be used as the niobium catalyst with the niobium oxide being present on a support. The support may be an oxide selected from the group consisting of silicon oxide, aluminum oxide, titanium oxide and mixtures thereof. The catalyst may be formed by reacting niobium fluoride with the oxide serving as the support. The niobium catalyst may contain elemental niobium within the range of 1 wt % to 70 wt %, and more preferably within the range of 10 wt % to 30 wt %. The process may be operated at a temperature from 150 to 450.degree. C. and preferably from 250 to 350.degree. C. The process may be operated at a pressure from 0.1 to 15 atm. absolute and preferably from 0.5-5 atm. absolute. The flow rate of reactants may be from 10 to 10,000 L/kg.sub.(cat) /h, and preferably from 100 to 1,000 L/kg.sub.(cat) /h.

IMPROVEMENT OF THE EXTRACTION SEPARATION OF URANIUM AND ZIRCONIUM USING ZIRCONIUM-MASKING REAGENTS (in German)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kyrs, M.; Caletka, R.; Selucky, P.

1963-12-01

The masking capacities of a series of reagents were studied in the zirconium extraction with tributyl phosphate solution in the presence of nitric acid. It was established that with many reagents an improvement of the separation of uranium from zirconium could be obtained. The efficiency of the reagents increases in the series tannin, oxalic acid, tiron, pyrogallol, and Arsenazo I. (tr-auth)

Production of nuclear grade zirconium: A review

NASA Astrophysics Data System (ADS)

Xu, L.; Xiao, Y.; van Sandwijk, A.; Xu, Q.; Yang, Y.

2015-11-01

Zirconium is an ideal material for nuclear reactors due to its low absorption cross-section for thermal neutrons, whereas the typically contained hafnium with strong neutron-absorption is very harmful for zirconium as a fuel cladding material. This paper provides an overview of the processes for nuclear grade zirconium production with emphasis on the methods of Zr-Hf separation. The separation processes are roughly classified into hydro- and pyrometallurgical routes. The known pyrometallurgical Zr-Hf separation methods are discussed based on the following reaction features: redox characteristics, volatility, electrochemical properties and molten salt-metal equilibrium. In the present paper, the available Zr-Hf separation technologies are compared. The advantages and disadvantages as well as future directions of research and development for nuclear grade zirconium production are discussed.

Initial Assessment of CSA Group Niobium Boron Based Coatings on 4340 Steel

DTIC Science & Technology

2017-07-01

Technical Report ARWSB-TR-17026 Initial Assessment of CSA Group Niobium- Boron Based Coatings on 4340 Steel C.P. Mulligan...REPORT TYPE Technical 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Initial Assessment of CSA Group Niobium- Boron Based Coatings on 4340...metallographic mounts reported as (1) thin and (2) thick Niobium- Boron (Nb-B) type coatings on steel. CSA Group is interested in providing coatings for potential

THE COLORIMETRIC DETERMINATION OF VANADIUM IN NIOBIUM-VANADIUM ALLOYS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Articolo, O.J.

1959-06-26

A procedure is described for the analysis of vanadium in niobium-- vanadium alloys in the range >0.1% vanadium with an accuracy of better than 3%. The method was applied to the analysis of niobium alloys in which the nominal per cent vanadium varied between 0.3 to 4.6%. The sample is dissolved in a mixture of nitric and hydrofluoric acid and then evaporated to fumes with sulfuric acid. The niobium is hydrolyzed with sulfurous acid and separated from the vanadium by filtration. Hydrogen peroxide is added to the filtrate to form a reddish brown complex with the vanadium. The optical densitymore » of the resulting solution is obtained at 450 m mu on a model B Beckman spectrophotometer. (auth)« less

Method for etching thin films of niboium and niobium-containing compounds for preparing superconductive circuits

DOEpatents

Kampwirth, R.T.; Schuller, I.K.; Falco, C.M.

1979-11-23

An improved method of preparing thin film superconducting electrical circuits of niobium or niobium compounds is provided in which a thin film of the niobium or niobium compound is applied to a nonconductive substrate and covered with a layer of photosensitive material. The sensitive material is in turn covered with a circuit pattern exposed and developed to form a mask of the circuit in photoresistive material on the surface of the film. The unmasked excess niobium film is removed by contacting the substrate with an aqueous etching solution of nitric acid, sulfuric acid, and hydrogen fluoride, which will rapidly etch the niobium compound without undercutting the photoresist. A modification of the etching solution will permit thin films to be lifted from the substrate without further etching.

Extraction spectrophotometric determination of niobium in rocks with sulfochlorophenol S

USGS Publications Warehouse

Childress, A.E.; Greenland, L.P.

1980-01-01

After acid decomposition and potassium pyrosulfate fusion, niobium (1-26 ppm) is separated from interfering elements by extraction into methyl isobutyl ketone from 6 M H2SO4-2 M HF and back-extracted into water. The niobium-sulfochloro-phenol S complex is extracted into amyl alcohol. ?? 1980.

Welding Niobium Bearing HSLA Steels 'Myths and Magic'

NASA Astrophysics Data System (ADS)

Kirkwood, Phil

Niobium is not currently added to ferritic steels with the specific objective of improving weldability and is more likely to be present to harness its combined beneficial effects on strength and toughness. Nevertheless, as carbon levels in many classes of HSLA steel, are progressively reduced, there is an increasing awareness that, amongst the microalloying elements, niobium is uniquely placed to deliver the mechanical property combinations that modern specifications demand and simultaneously deliver a `bonus' by way of enhanced weldability.

Production of nanocrystalline metal powders via combustion reaction synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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

Molybdenum

Integrated Risk Information System (IRIS)

Molybdenum ; CASRN 7439 - 98 - 7 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 Noncarcinogenic Effec

The Development of Molybdenum Speciation as a Paleoredox Tool

NASA Astrophysics Data System (ADS)

Rodley, J.; Peacock, C.; Mosselmans, J. F. W.; Poulton, S.

2017-12-01

The redox state of the oceans has changed throughout geological time and an understanding of these changes is essential to elucidate links between ocean chemistry, climate and life. Due to its abundance in seawater and redox-sensitive nature, molybdenum has enormous potential as a paleoredox proxy. Although a significant amount of research has been done on molybdenum in ancient and modern sediments in terms of its concentrations and isotopic ratios there remains a limited understanding of the drawdown mechanisms of molybdenum under different redox conditions restricting its use in identifying a range of redox states. In order to address these uncertainties, we have developed a novel sequential extraction technique to examine molybdenum concentrations in six sediment fractions from modern samples that represent oxic, nitrogenous, ferruginous and euxinic environments. In addition we use µ-XRF and µ-XANES synchrotron spectroscopy to examine the molybdenum speciation within these fractions and environments. To interpret our µ-XANES data we have developed an extensive library of molybdenum XANES standards that represent molybdenum sequestration by the sediment fractions identified from the sequential extraction. To further verify our synchrotron results we developed a series of µ-XANES micro-column experiments to examine preferential uptake pathways of molybdenum to different sediment phases under a euxinic water column. The initial data from both the sequential extraction and µ-XANES methods indicate that molybdenum is not limited to a single burial pathway in any of the redox environments. We find that each of the redox environments can be characterised by a limited set of molybdenum phase associations, with molybdenum adsorption to pyrite likely the dominant burial pathway. These findings agree with existing research for molybdenum speciation in euxinic environments suggesting that both pyrite and sulphidised organic matter act as important molybdenum sinks. Our

Mineral resource of the month: molybdenum

USGS Publications Warehouse

Magyar, Michael J.

2004-01-01

Molybdenum is a metallic element that is most frequently used in alloy and stainless steels, which together represent the single largest market for molybdenum. Molybdenum has also proven invaluable in carbon steel, cast iron and superalloys. Its alloying versatility is unmatched because its addition enhances material performance under high-stress conditions in expanded temperature ranges and in highly corrosive environments. The metal is also used in catalysts, other chemicals, lubricants and many other applications.

Quercetin as colorimetric reagent for determination of zirconium

USGS Publications Warehouse

Grimaldi, F.S.; White, C.E.

1953-01-01

Methods described in the literature for the determination of zirconium are generally designed for relatively large amounts of this element. A good procedure using colorimetric reagent for the determination of trace amounts is desirable. Quercetin has been found to yield a sensitive color reaction with zirconium suitable for the determination of from 0.1 to 50?? of zirconium dioxide. The procedure developed involves the separation of zirconium from interfering elements by precipitation with p-dimethylaminoazophenylarsonic acid prior to its estimation with quercetin. The quercetin reaction is carried out in 0.5N hydrochloric acid solution. Under the operating conditions it is indicated that quercetin forms a 2 to 1 complex with zirconium; however, a 2 to 1 and a 1 to 1 complex can coexist under special conditions. Approximate values for the equilibrium constants of the complexes are K1 = 0.33 ?? 10-5 and K2 = 1.3 ?? 10-9. Seven Bureau of Standards samples of glass sands and refractories were analyzed with excellent results. The method described should find considerable application in the analysis of minerals and other materials for macro as well as micro amounts of zirconium.

CHARACTERISTICS OF ANODIC AND CORROSION FILMS ON ZIRCONIUM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Misch, R.D.

1960-05-01

Zirconium anodizes similarly to tungsten in respect to the change of interference colors with applied voltage. However, the oxide layer on tungsten cannot reach as great a thickness. Hafnium does not anodize in the same way as zirconium but is similar to tantalum. By measuring the interference color and capacitative thicknesses on zirconium (Grades I and III) and a 2.5 wt.% tin ailoy, the film was found to grow less rapidly in terms of capacitance than in terms of iaterference colors. This was interpreted to mean that cracks develop in the oxide as it thickens. The effect was most pronouncedmore » on Grade III zirconium and least pronounced on the tin alloy. The reduction in capacitative thickness was especially noticeable when white oxide appeared. Comparative measurements on Grade I zirconium and 2.5 wt.% tin alloy indicated that the thickness of the oxide film on the tin alloy (after 16 hours in water) increased more rapidly with temperature than the film on zirconium. Tin is believed to act in ways to counteract the tendency of the oxide to form cracks, and to produce vacancies which promote ionic diffusion. (auth)« less

Review of ingot niobium as a material for superconducting radiofrequency accelerating cavities

NASA Astrophysics Data System (ADS)

Kneisel, P.; Ciovati, G.; Dhakal, P.; Saito, K.; Singer, W.; Singer, X.; Myneni, G. R.

2015-02-01

As a result of collaboration between Jefferson Lab and niobium manufacturer Companhia Brasileira de Metalurgia e Mineração (CBMM), ingot niobium was explored as a possible material for superconducting radiofrequency (SRF) cavity fabrication. The first single cell cavity from large-grain high purity niobium was fabricated and successfully tested at Jefferson Lab in 2004. This work triggered research activities in other SRF laboratories around the world. Large-grain (LG) niobium became not only an interesting alternative material for cavity builders, but also material scientists and surface scientists were eager to participate in the development of this technology. Many single cell cavities made from material of different suppliers have been tested successfully and several multi-cell cavities have shown performances comparable to the best cavities made from standard fine-grain niobium. Several 9-cell cavities fabricated by Research Instruments and tested at DESY exceeded the best performing fine grain cavities with a record accelerating gradient of Eacc=45.6 MV/m. The quality factor of those cavities was also higher than that of fine-grain (FG) cavities processed with the same methods. Such performance levels push the state-of-the art of SRF technology and are of great interest for future accelerators. This contribution reviews the development of ingot niobium technology and highlights some of the differences compared to standard FG material and opportunities for further developments.

Precipitation of hydrides in high purity niobium after different treatments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barkov, F.; Romanenko, A.; Trenikhina, Y.

Precipitation of lossy non-superconducting niobium hydrides represents a known problem for high purity niobium in superconducting applications. Using cryogenic optical and laser confocal scanning microscopy we have directly observed surface precipitation and evolution of niobium hydrides in samples after different treatments used for superconducting RF cavities for particle acceleration. Precipitation is shown to occur throughout the sample volume, and the growth of hydrides is well described by the fast diffusion-controlled process in which almost all hydrogen is precipitated atmore » $T=140$~K within $$\\sim30$$~min. 120$$^{\\circ}$$C baking and mechanical deformation are found to affect hydride precipitation through their influence on the number of nucleation and trapping centers.« less

Silicon nitride reinforced with molybdenum disilicide

DOEpatents

Petrovic, John J.; Honnell, Richard E.

1991-01-01

Compositions of matter comprised of silicon nitride and molybdenum disilicide and methods of making the compositions, where the molybdenum disilicide is present in amounts ranging from about 5 to about 50 vol. %.

DISSOLUTION OF ZIRCONIUM-CONTAINING FUEL ELEMENTS

DOEpatents

Horn, F.L.

1961-12-12

Uranium is recovered from spent uranium fuel elements containing or clad with zirconium. These fuel elements are placed in an anhydrous solution of hydrogen fluoride and nitrogen dioxide. Within this system uranium forms a soluble complex and zirconium forms an insoluble complex. The uranium can then be separated, treated, and removed from solution as uranium hexafluoride. (AEC)

Niobium oxide nanocolumns formed via anodic alumina with modulated pore diameters

NASA Astrophysics Data System (ADS)

Pligovka, A.; Zakhlebayeva, A.; Lazavenka, A.

2018-03-01

Niobium oxide nanocolumns with modulated diameters were formed for the first time. An Al/Nb bilayer specimen was prepared by successive sputter-deposition of 300 nm niobium layer and 1200 nm aluminum layer onto silicon wafer. Regular anodic alumina matrix with modulated pore diameters was formed by sequential anodization of initial specimen in tartaric acid at 180 V, and in oxalic acid at 37 V. Further potentiodynamic reanodization of the specimen up to 400 V causes the simultaneous growth of 440 nm continuous niobium oxide layer beneath the alumina film and two types of an array of oxide nanocolumns (thick – with 100 nm width and 630 nm high and thin – with 25 nm width and 170 nm high), which are the filling of the alumina pores. The morphology of the formed anodic niobium oxide nanocolumns with modulated diameters was determined by field emission scanning electron microscopy. The formed nanostructures can be used for perspective devices of nano- and optoelectronics such as photonic crystals.

Investigation of niobium surface structure and composition for improvement of superconducting radio-frequency cavities

NASA Astrophysics Data System (ADS)

Trenikhina, Yulia

Nano-scale investigation of intrinsic properties of niobium near-surface is a key to control performance of niobium superconducting radio-frequency cavities. Mechanisms responsible for the performance limitations and their empirical remedies needs to be justified in order to reproducibly control fabrication of SRF cavities with desired characteristics. The high field Q-slope and mechanism behind its cure (120°C mild bake) were investigated by comparison of the samples cut out of the cavities with high and low dissipation regions. Material evolution during mild field Q-slope nitrogen treatment was characterized using the coupon samples as well as samples cut out of nitrogen treated cavity. Evaluation of niobium near-surface state after some typical and novel cavity treatments was accomplished. Various TEM techniques, SEM, XPS, AES, XRD were used for the structural and chemical characterization of niobium near-surface. Combination of thermometry and structural temperature-dependent comparison of the cavity cutouts with different dissipation characteristics revealed precipitation of niobium hydrides to be the reason for medium and high field Q-slopes. Step-by-step effect of the nitrogen treatment processing on niobium surface was studied by analytical and structural characterization of the cavity cutout and niobium samples, which were subject to the treatment. Low concentration nitrogen doping is proposed to explain the benefit of nitrogen treatment. Chemical characterization of niobium samples before and after various surface processing (Electropolishing (EP), 800°C bake, hydrofluoric acid (HF) rinsing) showed the differences that can help to reveal the microscopic effects behind these treatments as well as possible sources of surface contamination.

Processing fissile material mixtures containing zirconium and/or carbon

DOEpatents

Johnson, Michael Ernest; Maloney, Martin David

2013-07-02

A method of processing spent TRIZO-coated nuclear fuel may include adding fluoride to complex zirconium present in a dissolved TRIZO-coated fuel. Complexing the zirconium with fluoride may reduce or eliminate the potential for zirconium to interfere with the extraction of uranium and/or transuranics from fission materials in the spent nuclear fuel.

Nanoindentation study of bulk zirconium hydrides at elevated temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cinbiz, Mahmut Nedim; Balooch, Mehdi; Hu, Xunxiang

Here, the mechanical properties of zirconium hydrides was studied using nano-indentation technique at a temperature range of 25 – 400 °C. Temperature dependency of reduced elastic modulus and hardness of δ- and ε-zirconium hydrides were obtained by conducting nanoindentation experiments on the bulk hydride samples with independently heating capability of indenter and heating stage. The reduced elastic modulus of δ-zirconium hydride (H/Zr ratio =1.61) decreased from ~113 GPa to ~109 GPa while temperature increased from room temperature to 400°C. For ε-zirconium hydrides (H/Zr ratio=1.79), the reduced elastic modulus decreased from 61 GPa to 54 GPa as temperature increased from roommore » temperature to 300 °C. Whereas, hardness of δ-zirconium hydride significantly decreased from 4.1 GPa to 2.41 GPa when temperature increased from room temperature to 400 °C. Similarly, hardness of ε-zirconium hydride decreased from 3.06 GPa to 2.19 GPa with temperature increase from room temperature to 300°C.« less

Nanoindentation study of bulk zirconium hydrides at elevated temperatures

DOE PAGES

Cinbiz, Mahmut Nedim; Balooch, Mehdi; Hu, Xunxiang; ...

2017-08-02

Here, the mechanical properties of zirconium hydrides was studied using nano-indentation technique at a temperature range of 25 – 400 °C. Temperature dependency of reduced elastic modulus and hardness of δ- and ε-zirconium hydrides were obtained by conducting nanoindentation experiments on the bulk hydride samples with independently heating capability of indenter and heating stage. The reduced elastic modulus of δ-zirconium hydride (H/Zr ratio =1.61) decreased from ~113 GPa to ~109 GPa while temperature increased from room temperature to 400°C. For ε-zirconium hydrides (H/Zr ratio=1.79), the reduced elastic modulus decreased from 61 GPa to 54 GPa as temperature increased from roommore » temperature to 300 °C. Whereas, hardness of δ-zirconium hydride significantly decreased from 4.1 GPa to 2.41 GPa when temperature increased from room temperature to 400 °C. Similarly, hardness of ε-zirconium hydride decreased from 3.06 GPa to 2.19 GPa with temperature increase from room temperature to 300°C.« less

URANIUM DECONTAMINATION

DOEpatents

Buckingham, J.S.; Carroll, J.L.

1959-12-22

A process is described for reducing the extractability of ruthenium, zirconium, and niobium values into hexone contained in an aqueous nitric acid uranium-containing solution. The solution is made acid-deficient, heated to between 55 and 70 deg C, and at that temperature a water-soluble inorganic thiosulfate is added. By this, a precipitate is formed which carries the bulk of the ruthenium, and the remainder of the ruthenium as well as the zirconium and niobium are converted to a hexone-nonextractable form. The rutheniumcontaining precipitate can either be removed from the solu tion or it can be dissolved as a hexone-non-extractable compound by the addition of sodium dichromate prior to hexone extraction.

Review of ingot niobium as a material for superconducting radiofrequency accelerating cavities

DOE PAGES

Kneisel, P.; Ciovati, G.; Dhakal, P.; ...

2014-12-01

As a result of collaboration between Jefferson Lab and niobium manufacturer Companhia Brasileira de Metalurgia e Mineração (CBMM), ingot niobium was explored as a possible material for superconducting radiofrequency (SRF) cavity fabrication. The first single cell cavity from large-grain high purity niobium was fabricated and successfully tested at Jefferson Lab in 2004. This work triggered research activities in other SRF laboratories around the world. The large-grain (LG) niobium became not only an interesting alternative material for cavity builders, but also material scientists and surface scientists were eager to participate in the development of this technology. Many single cell cavities mademore » from material of different suppliers have been tested successfully and several multi-cell cavities have shown performances comparable to the best cavities made from standard fine-grain niobium. Several 9-cell cavities fabricated by Research Instruments and tested at DESY exceeded the best performing fine grain cavities with a record accelerating gradient of E acc=45.6 MV/m. The quality factor of those cavities was also higher than that of fine-grain (FG) cavities processed with the same methods. Such performance levels push the state-of-the art of SRF technology and are of great interest for future accelerators. This contribution reviews the development of ingot niobium technology and highlights some of the differences compared to standard FG material and opportunities for further developments.« less

Efficient UV-emitting X-ray phosphors: octahedral Zr(PO 4) 6 luminescence centers in potassium hafnium-zirconium phosphates K 2Hf 1- xZr x(PO 4) 2 and KHf 2(1- x) Zr 2 x(PO 4) 3

NASA Astrophysics Data System (ADS)

Torardi, C. C.; Miao, C. R.; Li, J.

2003-02-01

Potassium hafnium-zirconium phosphates, K 2Hf 1- xZr x(PO 4) 2 and KHf 2(1- x) Zr 2 x(PO 4) 3, are broad-band UV-emitting phosphors. At room temperature, they have emission peak maxima at approximately 322 and 305 nm, respectively, under 30 kV peak molybdenum X-ray excitation. Both phosphors demonstrate luminescence efficiencies that make them up to ˜60% as bright as commercially available CaWO 4 Hi-Plus. The solid-state and flux synthesis conditions, and X-ray excited UV luminescence of these two phosphors are discussed. Even though the two compounds have different atomic structures, they contain zirconium in the same active luminescence environment as that found in highly efficient UV-emitting BaHf 1- xZr x(PO 4) 2. All the three materials have hafnium and zirconium in octahedral coordination via oxygen-atom corner sharing with six separate PO 4 tetrahedra. This octahedral Zr(PO 4) 6 moiety appears to be an important structural element for efficient X-ray excited luminescence, as are the edge-sharing octahedral TaO 6 chains for tantalate emission.

Atomically Thin-Layered Molybdenum Disulfide (MoS2) for Bulk-Heterojunction Solar Cells.

PubMed

Singh, Eric; Kim, Ki Seok; Yeom, Geun Young; Nalwa, Hari Singh

2017-02-01

Transition metal dichalcogenides (TMDs) are becoming significant because of their interesting semiconducting and photonic properties. In particular, TMDs such as molybdenum disulfide (MoS 2 ), molybdenum diselenide (MoSe 2 ), tungsten disulfide (WS 2 ), tungsten diselenide (WSe 2 ), titanium disulfide (TiS 2 ), tantalum sulfide (TaS 2 ), and niobium selenide (NbSe 2 ) are increasingly attracting attention for their applications in solar cell devices. In this review, we give a brief introduction to TMDs with a focus on MoS 2 ; and thereafter, emphasize the role of atomically thin MoS 2 layers in fabricating solar cell devices, including bulk-heterojunction, organic, and perovskites-based solar cells. Layered MoS 2 has been used as the hole-transport layer (HTL), electron-transport layer (ETL), interfacial layer, and protective layer in fabricating heterojunction solar cells. The trilayer graphene/MoS 2 /n-Si solar cell devices exhibit a power-conversion efficiency of 11.1%. The effects of plasma and chemical doping on the photovoltaic performance of MoS 2 solar cells have been analyzed. After doping and electrical gating, a power-conversion efficiency (PCE) of 9.03% has been observed for the MoS 2 /h-BN/GaAs heterostructure solar cells. The MoS 2 -containing perovskites-based solar cells show a PCE as high as 13.3%. The PCE of MoS 2 -based organic solar cells exceeds 8.40%. The stability of MoS 2 solar cells measured under ambient conditions and light illumination has been discussed. The MoS 2 -based materials show a great potential for solar cell devices along with high PCE; however, in this connection, their long-term environmental stability is also of equal importance for commercial applications.

Molybdenum sealing glass-ceramic composition

DOEpatents

Eagan, Robert J.

1976-01-01

The invention relates to a glass-ceramic composition having low hydrogen and helium permeability properties, along with high fracture strength, a thermal coefficient of expansion similar to that of molybdenum, and adaptable for hermetically sealing to molybdenum at temperatures of between about 900.degree. and about 950.degree.C. to form a hermatically sealed insulator body.

Spectrophotometric determination of molybdenum in rocks with thiocyanate

USGS Publications Warehouse

Lillie, E.G.; Greenland, L.P.

1974-01-01

A rapid procedure for the determination of microgram amounts of molybdenum in rocks is described. After acid decomposition, molybdenum is extracted from a hydrochloric acid solution into xylene with tributyl phosphate. After back-extraction with water, molybdenum is extracted as the ??-benzoinoximate into chloroform, stripped into hydrochloric acid extracted as the thiocyanate into amyl alcohol, and determined spectrophotometrically. The molybdenum thiocyanate color produced is stable, sensitive, and reproducible. Results of analyses of several of the U.S. Geological Survey standard rocks are given. ?? 1974.

Molybdenum-A Key Component of Metal Alloys

USGS Publications Warehouse

Kropschot, S.J.

2010-01-01

Molybdenum, whose chemical symbol is Mo, was first recognized as an element in 1778. Until that time, the mineral molybdenite-the most important source of molybdenum-was believed to be a lead mineral because of its metallic gray color, greasy feel, and softness. In the late 19th century, French metallurgists discovered that molybdenum, when alloyed (mixed) with steel in small quantities, creates a substance that is remarkably tougher than steel alone and is highly resistant to heat. The alloy was found to be ideal for making tools and armor plate. Today, the most common use of molybdenum is as an alloying agent in stainless steel, alloy steels, and superalloys to enhance hardness, strength, and resistance to corrosion.

Evaluation of Niobium as Candidate Electrode Material for DC High Voltage Photoelectron Guns

NASA Technical Reports Server (NTRS)

BastaniNejad, M.; Mohamed, Abdullah; Elmustafa, A. A.; Adderley, P.; Clark, J.; Covert, S.; Hansknecht, J.; Hernandez-Garcia, C.; Poelker, M.; Mammei, R.;

40 CFR 721.10089 - Modified salicylic acid, zirconium complex (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Modified salicylic acid, zirconium... Specific Chemical Substances § 721.10089 Modified salicylic acid, zirconium complex (generic). (a) Chemical... as modified salicylic acid, zirconium complex (PMN P-00-552) is subject to reporting under this...

40 CFR 721.10089 - Modified salicylic acid, zirconium complex (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Modified salicylic acid, zirconium... Specific Chemical Substances § 721.10089 Modified salicylic acid, zirconium complex (generic). (a) Chemical... as modified salicylic acid, zirconium complex (PMN P-00-552) is subject to reporting under this...

Superconducting 500 MHz accelerating copper cavities sputter-coated with niobium films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benvenuti, C.; Circelli, N.; Hauer, M.

Thermal breakdown induced either by electron loading or by local defects of enhanced RF losses limits the accelerating field of superconducting niobium cavities. Replacing niobium with a material of higher thermal conductivity would be highly desirable to increase the maximum field. Therefore, cavities made of OFHC copper were coated by D.C. bias sputtering with a thin niobium film (1.5 to 5 ..mu..). Accelerating fields up to 8.6 MVm/sup -1/ were obtained without observing any field breakdown, the limitation being due to the available rf power. The Q values achieved at 4.2 K and low field were similar to those ofmore » niobium sheet cavities (i.e. about 2 x 10/sup 9/), but a fast initial decrease of Q to about 10/sup 9/ was reproducibly experienced. Subsequent inspection of regions of enhanced rf losses revealed defects the origin of which is under study. The apparatus used for coating the cavities and the results obtained are presented and discussed.« less

RECOVERY OF URANIUM FROM ZIRCONIUM-URANIUM NUCLEAR FUELS

DOEpatents

Gens, T.A.

1962-07-10

An improvement was made in a process of recovering uranium from a uranium-zirconium composition which was hydrochlorinated with gsseous hydrogen chloride at a temperature of from 350 to 800 deg C resulting in volatilization of the zirconium, as zirconium tetrachloride, and the formation of a uranium containing nitric acid insoluble residue. The improvement consists of reacting the nitric acid insoluble hydrochlorination residue with gaseous carbon tetrachloride at a temperature in the range 550 to 600 deg C, and thereafter recovering the resulting uranium chloride vapors. (AEC)

Method for fabricating uranium alloy articles without shape memory effects

DOEpatents

Banker, John G.

1985-01-01

Uranium-rich niobium and niobium-zirconium alloys possess a characteristic known as shape memory effect wherein shaped articles of these alloys recover their original shape when heated. The present invention circumvents this memory behavior by forming the alloys into the desired configuration at elevated temperatures with "cold" matched dies and maintaining the shaped articles between the dies until the articles cool to ambient temperature.

Method for fabricating uranium alloy articles without shape memory effects

DOEpatents

Banker, J.G.

1980-05-21

Uranium-rich niobium and niobium-zirconium alloys possess a characteristic known as shape memory effect wherein shaped articles of these alloys recover their original shape when heated. The present invention circumvents this memory behavior by forming the alloys into the desired configuration at elevated temperatures with cold matched dies and maintaining the shaped articles between the dies until the articles cool to ambient temperature.

Molybdenum sulfide/carbide catalysts

DOEpatents

Alonso, Gabriel [Chihuahua, MX; Chianelli, Russell R [El Paso, TX; Fuentes, Sergio [Ensenada, MX; Torres, Brenda [El Paso, TX

2007-05-29

The present invention provides methods of synthesizing molybdenum disulfide (MoS.sub.2) and carbon-containing molybdenum disulfide (MoS.sub.2-xC.sub.x) catalysts that exhibit improved catalytic activity for hydrotreating reactions involving hydrodesulfurization, hydrodenitrogenation, and hydrogenation. The present invention also concerns the resulting catalysts. Furthermore, the invention concerns the promotion of these catalysts with Co, Ni, Fe, and/or Ru sulfides to create catalysts with greater activity, for hydrotreating reactions, than conventional catalysts such as cobalt molybdate on alumina support.

Transfer of molybdenum disulfide to various metals

NASA Technical Reports Server (NTRS)

Barton, G. C.; Pepper, S. V.

1977-01-01

Sliding friction experiments were conducted with molybdenum disulfide single crystals in contact with sputter cleaned surfaces of copper, nickel, gold, and 304 stainless steel. Transfer of the molybdenum disulfide to the metals was monitored with Auger electron spectroscopy. Results of the investigation indicate molybdenum disulfide transfers to all clean metal surfaces after a single pass over the metal surface with film thickness observed to increase with repeated passes over the same surfaces. Large particle transfer occurs when the orientation of the crystallites is other than basal. This is frequently accompanied by abrasion of the metal. Adhesion of molybdenum disulfide films occurred readily to copper and nickel, less readily to 304 stainless steel, and even less effectively to the gold, which indicates a chemical effect.

Molybdenum Enzymes, Cofactors, and Model Systems.

ERIC Educational Resources Information Center

Burgmayer, S. J. N; Stiefel, E. I.

1985-01-01

Discusses: (l) molybdoenzymes (examining their distribution and metabolic role, composition and redox strategy, cofactors, substrate reactions, and mechanistic possibilities); (2) structural information on molybdenum (Mo) centers; (3) modeling studies (Mo-co models, nitrogenase models, and the MO-S duo); and (4) the copper-molybdenum antagonism.…

PROCESS OF DISSOLVING ZIRCONIUM ALLOYS

DOEpatents

Shor, R.S.; Vogler, S.

1958-01-21

A process is described for dissolving binary zirconium-uranium alloys where the uranium content is about 2%. In prior dissolution procedures for these alloys, an oxidizing agent was added to prevent the precipitation of uranium tetrafluoride. In the present method complete dissolution is accomplished without the use of the oxidizing agent by using only the stoichiometric amount or slight excess of HF required by the zirconium. The concentration of the acid may range from 2M to 10M and the dissolution is advatageously carried out at a temperature of 80 deg C.

NIOBIUM-TANTALUM SEPARATION

DOEpatents

Wilhelm, H.A.; Foos, R.A.

1959-01-27

The usual method for the separation of tantalum and niobium consists of a selective solvent extraction from an aqueous hydrofluoric acid solution of the metals. A difficulty encountered in this process is the fact that the corrosion problems associated with hydrofluoric acid are serious. It has been found that the corrosion caused by the hydrofluoric acid may be substantially reduced by adding to the acidic solution an amine, such as phenyl diethanolamine or aniline, and adjusting pH value to between 4 and 6.

Nanophase Nickel-Zirconium Alloys for Fuel Cells

NASA Technical Reports Server (NTRS)

Narayanan, Sekharipuram; Whitacre, jay; Valdez, Thomas

2008-01-01

Nanophase nickel-zirconium alloys have been investigated for use as electrically conductive coatings and catalyst supports in fuel cells. Heretofore, noble metals have been used because they resist corrosion in the harsh, acidic fuel cell interior environments. However, the high cost of noble metals has prompted a search for less-costly substitutes. Nickel-zirconium alloys belong to a class of base metal alloys formed from transition elements of widely different d-electron configurations. These alloys generally exhibit unique physical, chemical, and metallurgical properties that can include corrosion resistance. Inasmuch as corrosion is accelerated by free-energy differences between bulk material and grain boundaries, it was conjectured that amorphous (glassy) and nanophase forms of these alloys could offer the desired corrosion resistance. For experiments to test the conjecture, thin alloy films containing various proportions of nickel and zirconium were deposited by magnetron and radiofrequency co-sputtering of nickel and zirconium. The results of x-ray diffraction studies of the deposited films suggested that the films had a nanophase and nearly amorphous character.

Layer Protecting the Surface of Zirconium Used in Nuclear Reactors.

PubMed

Ashcheulov, Petr; Skoda, Radek; Skarohlíd, Jan; Taylor, Andrew; Fendrych, Frantisek; Kratochvílová, Irena

2016-01-01

Zirconium alloys have very useful properties for nuclear facilities applications having low absorption cross-section of thermal electrons, high ductility, hardness and corrosion resistance. However, there is also a significant disadvantage: it reacts with water steam and during this (oxidative) reaction it releases hydrogen gas, which partly diffuses into the alloy forming zirconium hydrides. A new strategy for surface protection of zirconium alloys against undesirable oxidation in nuclear reactors by polycrystalline diamond film has been patented- Czech patent 305059: Layer protecting the surface of zirconium alloys used in nuclear reactors and PCT patent: Layer for protecting surface of zirconium alloys (Patent Number: WO2015039636-A1). The zirconium alloy surface was covered by polycrystalline diamond layer grown in plasma enhanced chemical vapor deposition apparatus with linear antenna delivery system. Substantial progress in the description and understanding of the polycrystalline diamond/ zirconium alloys interface and material properties under standard and nuclear reactors conditions (irradiation, hot steam oxidation experiments and heating-quenching cycles) was made. In addition, process technology for the deposition of protective polycrystalline diamond films onto the surface of zirconium alloys was optimized. Zircaloy2 nuclear fuel pins were covered by 300 nm thick protective polycrystalline diamond layer (PCD) using plasma enhanced chemical vapor deposition apparatus with linear antenna delivery system. The polycrystalline diamond layer protects the zirconium alloy surface against undesirable oxidation and consolidates its chemical stability while preserving its functionality. PCD covered Zircaloy2 and standard Zircaloy2 pins were for 30 min. oxidized in 1100°C hot steam. Under these conditions α phase of zirconium changes to β phase (more opened for oxygen/hydrogen diffusion). PCD anticorrosion protection of Zircaloy nuclear fuel assemblies can

Evaluation of niobium as candidate electrode material for DC high voltage photoelectron guns

DOE PAGES

BastaniNejad, M.; Mohamed, Md. Abdullah; Elmustafa, A. A.; ...

2012-08-17

In this study, the field emission characteristics of niobium electrodes were compared to those of stainless steel electrodes using a DC high voltage field emission test apparatus. A total of eight electrodes were evaluated: two 304 stainless steel electrodes polished to mirror-like finish with diamond grit and six niobium electrodes (two single-crystal, two large-grain and two fine-grain) that were chemically polished using a buffered-chemical acid solution. Upon the first application of high voltage, the best large-grain and single-crystal niobium electrodes performed better than the best stainless steel electrodes, exhibiting less field emission at comparable voltage and gradient. In all cases,more » field emission from electrodes (stainless steel and/or niobium) could be significantly reduced and sometimes completely eliminated, by introducing krypton gas into the vacuum chamber while the electrode was biased at high voltage. Of all the electrodes tested, a large-grain niobium electrode performed the best, exhibiting no measurable field emission (< 10 pA) at 225 kV with 20 mm cathode/anode gap, corresponding to a gradient of 18.7 MV/m.« less

Characterization of high-purity niobium structures fabricated using the electron beam melting process

NASA Astrophysics Data System (ADS)

Terrazas Najera, Cesar Adrian

Additive Manufacturing (AM) refers to the varied set of technologies utilized for the fabrication of complex 3D components from digital data in a layer-by-layer fashion. The use of these technologies promises to revolutionize the manufacturing industry. The electron beam melting (EBM) process has been utilized for the fabrication of fully dense near-net-shape components from various metallic materials. This process, catalogued as a powder bed fusion technology, consists of the deposition of thin layers (50 - 120microm) of metallic powder particles which are fused by the use of a high energy electron beam and has been commercialized by Swedish company Arcam AB. Superconducting radio frequency (SRF) cavities are key components that are used in linear accelerators and other light sources for studies of elemental physics. Currently, cavity fabrication is done by employing different forming processes including deep-drawing and spinning. In both of the latter techniques, a feedstock high-purity niobium sheet with a thickness ranging from 3-4 mm is mechanically deformed and shaped into the desired geometry. In this manner, half cavities are formed that are later joined by electron beam welding (EBW). The welding step causes variability in the shape of the cavity and can also introduce impurities at the surface of the weld interface. The processing route and the purity of niobium are also of utmost importance since the presence of impurities such as inclusions or defects can be detrimental for the SRF properties of cavities. The focus of this research was the use of the EBM process in the manufacture of high purity niobium parts with potential SRF applications. Reactor grade niobium was plasma atomized and used as the precursor material for fabrication using EBM. An Arcam A2 system was utilized for the fabrication. The system had all internal components of the fabrication chamber replaced and was cleaned to prevent contamination of niobium powder. A mini-vat, developed at

Manufacturing process to reduce large grain growth in zirconium alloys

DOEpatents

Rosecrans, P.M.

1984-08-01

It is an object of the present invention to provide a procedure for desensitizing zirconium-based alloys to large grain growth (LGG) during thermal treatment above the recrystallization temperature of the alloy. It is a further object of the present invention to provide a method for treating zirconium-based alloys which have been cold-worked in the range of 2 to 8% strain to reduce large grain growth. It is another object of the present invention to provide a method for fabricating a zirconium alloy clad nuclear fuel element wherein the zirconium clad is resistant to large grain growth.

In vitro assessment of artifacts induced by titanium, titanium-zirconium and zirconium dioxide implants in cone-beam computed tomography.

PubMed

Sancho-Puchades, Manuel; Hämmerle, Christoph H F; Benic, Goran I

2015-10-01

The aim of this study was to test whether or not the intensity of artifacts around implants in cone-beam computed tomography (CBCT) differs between titanium, titanium-zirconium and zirconium dioxide implants. Twenty models of a human mandible, each containing one implant in the single-tooth gap position 45, were cast in dental stone. Five test models were produced for each of the following implant types: titanium 4.1 mm diameter (Ti4.1 ), titanium 3.3 mm diameter (Ti3.3 ), titanium-zirconium 3.3 mm diameter (TiZr3.3 ) and zirconium dioxide 3.5-4.5 mm diameter (ZrO3.5-4.5 ) implants. For control purposes, three models without implants were produced. Each model was scanned using a CBCT device. Gray values (GV) were recorded at eight circumferential positions around the implants at 0.5 mm, 1 mm and 2 mm from the implant surface (GVT est ). GV were assessed in the corresponding volumes of interest (VOI) in the control models without implants (GVC ontrol ). Differences of gray values (ΔGV) between GVT est and GVC ontrol were calculated as percentages. One-way ANOVA and post hoc tests were applied to detect differences between implant types. Mean ΔGV for ZrO3.5-4.5 presented the highest absolute values, generally followed by TiZr3.3 , Ti4.1 and Ti3.3 implants. The differences of ΔGV between ZrO3.5-4.5 and the remaining groups were statistically significant in the majority of the VOI (P ≤ 0.0167). ΔGV for TiZr3.3 , Ti4.1 and Ti3.3 implants did not differ significantly in the most VOI. For all implant types, ΔGV showed positive values buccally, mesio-buccally, lingually and disto-lingually, whereas negative values were detected mesially and distally. Zirconium dioxide implants generate significantly more artifacts as compared to titanium and titanium-zirconium implants. The intensity of artifacts around zirconium dioxide implants exhibited in average the threefold in comparison with titanium implants. © 2014 John Wiley & Sons A/S. Published by John Wiley

Molybdenum-UO2 cermet irradiation at 1145 K.

NASA Technical Reports Server (NTRS)

Mcdonald, G.

1971-01-01

Two molybdenum-uranium dioxide cermet fuel pins with molybdenum clad were fission-heated in a forced-convection helium coolant for sufficient time to achieve 5.3% burnup. The cermet core contained 20 wt % of 93.2% enriched uranium dioxide. The results were as follows: there was no visible change in the appearance of the molybdenum clad during irradiation; the maximum increase in diameter of the fuel pins was 0.8%; there was no migration of uranium dioxide along grain boundaries and no evident interaction between molybdenum and uranium dioxide; and, finally, approximately 12% of the fission gas formed was released from the cermet core into the gas plenum.

Spheroidization of molybdenum powder by radio frequency thermal plasma

NASA Astrophysics Data System (ADS)

Liu, Xiao-ping; Wang, Kuai-she; Hu, Ping; Chen, Qiang; Volinsky, Alex A.

2015-11-01

To control the morphology and particle size of dense spherical molybdenum powder prepared by radio frequency (RF) plasma from irregular molybdenum powder as a precursor, plasma process parameters were optimized in this paper. The effects of the carrier gas flow rate and molybdenum powder feeding rate on the shape and size of the final products were studied. The molybdenum powder morphology was examined using high-resolution scanning electron microscopy. The powder phases were analyzed by X-ray diffraction. The tap density and apparent density of the molybdenum powder were investigated using a Hall flow meter and a Scott volumeter. The optimal process parameters for the spherical molybdenum powder preparation are 50 g/min powder feeding rate and 0.6 m3/h carrier gas rate. In addition, pure spherical molybdenum powder can be obtained from irregular powder, and the tap density is enhanced after plasma processing. The average size is reduced from 72 to 62 µm, and the tap density is increased from 2.7 to 6.2 g/cm3. Therefore, RF plasma is a promising method for the preparation of high-density and high-purity spherical powders.

Biochemical abnormalities in workers exposed to molybdenum dust.

PubMed

Walravens, P A; Moure-Eraso, R; Solomons, C C; Chappell, W R; Bentley, G

1979-01-01

Exposure to molybdenum in dust was measured in a molybdenite roasting plant. This exposure was accompanied by large elevations of serum ceruloplasmin and smaller increases in mean serum uric acid levels in the workers. Absorption of molybdenum from the dust was demonstrated by increases in plasma and urinary molybdenum levels. It remains necessary to demonstrate whether such exposure results in long-term health effects.

Structure and mechanical properties of a multilayer carbide-hardened niobium composite material fabricated by diffusion welding

NASA Astrophysics Data System (ADS)

Korzhov, V. P.; Ershov, A. E.; Stroganova, T. S.; Prokhorov, D. V.

2016-04-01

The structure, the bending strength, and the fracture mechanism of an artificial niobium-based composite material, which is fabricated by high-pressure diffusion welding of multilayer stacks assembled from niobium foils with a two-sided carbon coating, are studied. The microstructure of the composite material is found to consist of alternating relatively plastic layers of the solid solution of carbon in niobium and hardening niobium carbide layers. The room-temperature proportional limit of the developed composite material is threefold that of the composite material fabricated from coating-free niobium foils using the proposed technology. The proportional limit of the developed composite material and the stress corresponding to the maximum load at 1100°C are 500 and 560 MPa, respectively. The developed material is considered as an alternative to Ni-Al superalloys.

Quench-age method for the fabrication of niobium-aluminum superconductors

DOEpatents

Pickus, Milton R.; Ciardella, Robert L.

1978-01-01

A flexible Nb.sub.3 Al superconducting wire is fabricated from a niobium-aluminum composite wire by heating to form a solid solution which is retained at room temperature as a metastable solid solution by quenching. The metastable solid solution is then transformed to the stable superconducting A-15 phase by low temperature aging. The transformation induced by aging can be controlled to yield either a multifilamentary or a solid A-15 core surrounded by ductile niobium.

Field dependent surface resistance of niobium on copper cavities

NASA Astrophysics Data System (ADS)

Junginger, T.

2015-07-01

The surface resistance RS of superconducting cavities prepared by sputter coating a niobium film on a copper substrate increases significantly stronger with the applied rf field compared to cavities of bulk material. A possible cause is that the thermal boundary resistance between the copper substrate and the niobium film induces heating of the inner cavity wall, resulting in a higher RS. Introducing helium gas in the cavity, and measuring its pressure as a function of applied field allowed to conclude that the inner surface of the cavity is heated up by less than 120 mK when RS increases with Eacc by 100 n Ω . This is more than one order of magnitude less than what one would expect from global heating. Additionally, the effects of cooldown speed and low temperature baking have been investigated in the framework of these experiments. It is shown that for the current state of the art niobium on copper cavities there is only a detrimental effect of low temperature baking. A fast cooldown results in a lowered RS.

Surface polishing of niobium for superconducting radio frequency (SRF) cavity applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Liang

2014-08-01

Niobium cavities are important components in modern particle accelerators based on superconducting radio frequency (SRF) technology. The interior of SRF cavities are cleaned and polished in order to produce high accelerating field and low power dissipation on the cavity wall. Current polishing methods, buffered chemical polishing (BCP) and electro-polishing (EP), have their advantages and limitations. We seek to improve current methods and explore laser polishing (LP) as a greener alternative of chemical methods. The topography and removal rate of BCP at different conditions (duration, temperature, sample orientation, flow rate) was studied with optical microscopy, scanning electron microscopy (SEM), and electronmore » backscatter diffraction (EBSD). Differential etching on different crystal orientations is the main contributor to fine grain niobium BCP topography, with gas evolution playing a secondary role. The surface of single crystal and bi-crystal niobium is smooth even after heavy BCP. The topography of fine grain niobium depends on total removal. The removal rate increases with temperature and surface acid flow rate within the rage of 0~20 °C, with chemical reaction being the possible dominate rate control mechanism. Surface flow helps to regulate temperature and avoid gas accumulation on the surface. The effect of surface flow rate on niobium EP was studied with optical microscopy, atomic force microscopy (AFM), and power spectral density (PSD) analysis. Within the range of 0~3.7 cm/s, no significant difference was found on the removal rate and the macro roughness. Possible improvement on the micro roughness with increased surface flow rate was observed. The effect of fluence and pulse accumulation on niobium topography during LP was studied with optical microscopy, SEM, AFM, and PSD analysis. Polishing on micro scale was achieved within fluence range of 0.57~0.90 J/cm2, with pulse accumulation adjusted accordingly. Larger area treatment was proved

METHOD OF MAKING DELTA ZIRCONIUM HYDRIDE MONOLITHIC MODERATOR PIECES

DOEpatents

Vetrano, J.B.

1962-01-23

A method is given for preparing large, sound bodies of delta zirconium hydride. The method includes the steps of heating a zirconium body to a temperature of not less than l000 deg C, providing a hydrogen atmosphere for the zirconium body at a pressure not greater than one atmosphere, reducing the temperature slowly to 800 deg C at such a rate that cracks do not form while maintaining the hydrogen pressure substantially constant, and cooling in an atmosphere of hydrogen. (AEC)

Zirconium fluoride glass - Surface crystals formed by reaction with water

NASA Technical Reports Server (NTRS)

Doremus, R. H.; Bansal, N. P.; Bradner, T.; Murphy, D.

1984-01-01

The hydrated surfaces of a zirconium barium fluoride glass, which has potential for application in optical fibers and other optical elements, were observed by scanning electron microscopy. Crystalline zirconium fluoride was identified by analysis of X-ray diffraction patterns of the surface crystals and found to be the main constituent of the surface material. It was also found that hydrated zirconium fluorides form only in highly acidic fluoride solutions. It is possible that the zirconium fluoride crystals form directly on the glass surface as a result of its depletion of other ions. The solubility of zirconium fluoride is suggested to be probably much lower than that of barium fluoride (0.16 g/100 cu cm at 18 C). Dissolution was determined to be the predominant process in the initial stages of the reaction of the glass with water. Penetration of water into the glass has little effect.

Minimalistic Liquid-Assisted Route to Highly Crystalline α-Zirconium Phosphate.

PubMed

Cheng, Yu; Wang, Xiaodong Tony; Jaenicke, Stephan; Chuah, Gaik-Khuan

2017-08-24

Zirconium phosphates have potential applications in areas of ion exchange, catalysis, photochemistry, and biotechnology. However, synthesis methodologies to form crystalline α-zirconium phosphate (Zr(HPO 4 ) 2 ⋅H 2 O) typically involve the use of excess phosphoric acid, addition of HF or oxalic acid and long reflux times or hydrothermal conditions. A minimalistic sustainable route to its synthesis has been developed by using only zirconium oxychloride and concentrated phosphoric acid to form highly crystalline α-zirconium phosphate within hours. The morphology can be changed from platelets to rod-shaped particles by fluoride addition. By varying the temperature and time, α-zirconium phosphate with particle sizes from nanometers to microns can be obtained. Key features of this minimal solvent synthesis are the excellent yields obtained with high atom economy under mild conditions and ease of scalability. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

DISSOLUTION OF ZIRCONIUM AND ALLOYS THEREFOR

DOEpatents

Swanson, J.L.

1961-07-11

The dissolution of zirconium cladding in a water solution of ammonium fluoride and ammonium nitrate is described. The method finds particular utility in processing spent fuel elements for nuclear reactors. The zirconium cladding is first dissolved in a water solution of ammonium fluoride and ammonium nitrate; insoluble uranium and plutonium fiuorides formed by attack of the solvent on the fuel materiai of the fuel element are then separated from the solution, and the fuel materiai is dissolved in another solution.

Oven rack having integral lubricious, dry porcelain surface

DOEpatents

Ambrose, Jeffrey A; Mackiewicz-Ludtka, Gail; Sikka, Vinod K; Qu, Jun

2014-06-03

A lubricious glass-coated metal cooking article capable of withstanding repeated heating and cooling between room temperature and at least 500.degree. F. without chipping or cracking the glass coating, wherein the glass coating includes about 0.1 to about 20% by weight of a homogeneously distributed dry refractory lubricant material having a particle size less than about 200 .mu.m. The lubricant material is selected from the group consisting of carbon; graphite; boron nitride; cubic boron nitride; molybdenum (FV) sulfide; molybdenum sulfide; molybdenum (IV) selenide; molybdenum selenide, tungsten (IV) sulfide; tungsten disulfide; tungsten sulfide; silicon nitride (Si.sub.3N.sub.4); TiN; TiC; TiCN; TiO.sub.2; TiAlN; CrN; SiC; diamond-like carbon; tungsten carbide (WC); zirconium oxide (ZrO.sub.2); zirconium oxide and 0.1 to 40 weight % aluminum oxide; alumina-zirconia; antimony; antimony oxide; antimony trioxide; and mixtures thereof.

Synthesis and photocatalytic activity of electrospun niobium oxide nanofibers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qi, Shishun; Zuo, Ruzhong, E-mail: piezolab@hfut.edu.cn; Liu, Yi

2013-03-15

Graphical abstract: Different morphologies are obtained for the electrospun niobium oxide nanofibers with different phase structures. The nanofibers of the two phase structures present different band gap value and the light absorption. Hexagonal phase nanofibers show better photocatalytic activity compared with the orthorhombic nanofibers. Highlights: ► Niobium oxide nanofibers of two phase structures were fabricated by electrospinning. ► Photocatalytic properties of the niobium oxide nanofibers were first explored. ► Nanofibers of different phase structures showed different photocatalytic activities. ► Reasons for the differences in the photocatalysis were carefully discussed. - Abstract: Niobium oxide (Nb{sub 2}O{sub 5}) nanofibers have been synthesizedmore » by sol–gel based electrospinning technique. Pure hexagonal phase (H-Nb{sub 2}O{sub 5}) and orthorhombic phase (O-Nb{sub 2}O{sub 5}) nanofibers were obtained by thermally annealing the electrospun Nb{sub 2}O{sub 5}/polyvinylpyrrolidone composite fibers in air at 500 °C and 700 °C, respectively. The fibers were characterized using the X-ray diffraction, scanning electron microscopy, specific surface area analyzer and UV–vis diffuse reflectance spectroscopy. Photocatalytic activities of the obtained nanofibers were evaluated depending on the degradation of methyl orange. The results indicate that the heat-treatment temperature, the crystalline structure and the morphology affected the physical and chemical properties of the as-prepared Nb{sub 2}O{sub 5} nanofibers. The H-Nb{sub 2}O{sub 5} nanofibers obtained at lower temperature showed better potential for the application as a promising photocatalyst.« less

The preparation of pure niobium for neutron dosimetry purposes

NASA Astrophysics Data System (ADS)

Schulze, Klaus; Krehl, Michael

1985-06-01

A technique is described for the preparation of high purity niobium for use in fast neutron dosimetry. Based on results of known purification processes for niobium, an optimized method has been developed, consisting of: (1) a double electrolytic refining in an eutectic lithium-, sodium-, potassium-fluoride melt, containing fluoro-potassium niobate (K 2NbF 7), (2) electron beam float zone melting (EBFZM) in ultra high vacuum (UHV) and (3) UHV treatments. Starting with EBFZM of niobium of commercial quality (140 μg/g Ta, 35 μg/g W) the tantalum and tungsten contents were reduced by a first electrolysis to approximately 4 and 4 × 10 -2 μg/g, respectively. For a second electrolytic refining using a salt bath with extremely low tantalum and tungsten contents, this material was subjected to an additional EBFZM process. The niobium metal produced by this step was three times zone melted to reduce those elements (e.g. Fe, Co, Ni, O, N) which increased during the electrolyses. Material produced by this technique has impurity concentrations below 0.4 μg/g of tantalum and 10 -2 μg/g of tungsten. The concentration of the interstitials (C, O, N except H) is below the detection limit of classical analytical methods. A further reduction of the interstitials by annealing treatments in UHV of this material resulted in an electrical residual resistivity ratio (RRR) ρ(295 K)/ ρ(4.2 K) = 24 500 indicating an impurity concentration far below 1 μg/g.

Low noise niobium dc SQUID with a planar input coil

NASA Astrophysics Data System (ADS)

de Waal, V. J.; van den Hamer, P.; Klapwijk, T. M.

1983-02-01

A practical all-niobium dc superconducting quantum interference device (SQUID) with a niobium spiral input coil has been developed. The SQUID utilizes submicron Josephson junctions. The best intrinsic energy resolution obtained with a 1-nH SQUID is 4×10-32 J/Hz. A 20-turn 1.2-μH input coil is coupled to a 2.3-nH SQUID with an efficiency of 0.5. The energy resolution with respect to the coil is 1×10-30 J/Hz.

International strategic minerals inventory summary report; zirconium

USGS Publications Warehouse

Towner, R.R.

1992-01-01

Zircon, a zirconium silicate, is currently the most important commercial zirconium-bearing mineral. Baddeleyite, a natural form of zirconia, is less important but has some specific end uses. Both zircon and baddeleyite occur in hard-rock and placer deposits, but at present all zircon production is from placer deposits. Most baddeleyite production is from hard-rock deposits, principally as a byproduct of copper and phosphate-rock mining. World zirconium resources in identified, economically exploitable deposits are about 46 times current production rates. Of these resources, some 71 percent are in South Africa, Australia, and the United States. The principal end uses of zirconium minerals are in ceramic applications and as refractories, abrasives, and mold linings in foundries. A minor amount, mainly of zircon, is used for the production of hafnium-free zirconium metal, which is used principally for sheathing fuel elements in nuclear reactors and in the chemical-processing industry, aerospace engineering, and electronics. Australia and South Africa are the largest zircon producers and account for more than 70 percent of world output; the United States and the Soviet Union account for another 20 percent. South Africa accounts for almost all the world's production of baddeleyite, which is about 2 percent of world production of contained zirconia. Australia and South Africa are the largest exporters of zircon. Unless major new deposits are developed in countries that have not traditionally produced zircon, the pattern of world production is unlikely to change by 2020. The proportions, however, of production that come from existing producing countries may change somewhat.

PROCESS FOR DISSOLVING BINARY URANIUM-ZIRCONIUM OR ZIRCONIUM-BASE ALLOYS

DOEpatents

Jonke, A.A.; Barghusen, J.J.; Levitz, N.M.

1962-08-14

A process of dissolving uranium-- zirconium and zircaloy alloys, e.g. jackets of fuel elements, with an anhydrous hydrogen fluoride containing from 10 to 32% by weight of hydrogen chloride at between 400 and 450 deg C., preferably while in contact with a fluidized inert powder, such as calcium fluoride is described. (AEC)

The Effect of Molybdenum Substrate Oxidation on Molybdenum Splat Formation

NASA Astrophysics Data System (ADS)

Wang, Jun; Li, Chang-Jiu

2018-01-01

Disk splats are usually observed when the deposition temperature exceeds the transition temperature, whereas thick oxide layer will reduce the adhesion resulting from high deposition temperature. In present study, single molybdenum splats were deposited onto polished molybdenum substrates with different preheating processes to clarify the effect of surface oxidation on the splat formation. Three substrate samples experienced three different preheating processes in an argon atmosphere. Two samples were preheated to 350 and 550 °C, and another sample was cooled to 350 °C after it was preheated to 550 °C. The chemistry and compositions of substrate surface were examined by XPS. The cross sections of splats were prepared by focus ion beam (FIB) and then characterized by SEM. Nearly disk-shaped splat with small fingers in the periphery was observed on the sample preheated to 350 °C. A perfect disk-shape splat was deposited at 550 °C. With the sample on the substrate preheated to 350 °C (cooling down from 550 °C), flower-shaped splat exhibited a central core and discrete periphery detached by some voids. The results of peeling off splats by carbon tape and the morphology of FIB sampled cross sections indicated that no effective bonding formed at the splat-substrate interface for the substrate ever heated to 550 °C, due to the increasing content of MoO3 on the preheated molybdenum surface.

Chemical compatibility of cartridge materials

NASA Technical Reports Server (NTRS)

Wilcox, Roy C.; Zee, R. H.

1991-01-01

This twelve month progress report deals with the chemical compatibility of semiconductor crystals grown in zero gravity. Specifically, it studies the chemical compatibility between TZM, a molybdenum alloy containing titanium and zirconium, and WC 103, a titanium alloy containing Niobium and Hafnium, and Gallium arsenide (GaAs) and Cadmium Zinc Tellurite (CdZnTe). Due to the health hazards involved, three approaches were used to study the chemical compatibility between the semiconductor and cartridge materials: reaction retort, thermogravimetric analysis, and bulk cylindrical cartridge containers. A scanning electron microscope with an energy dispersive X-ray analyzer was used to examine all samples after testing. The first conclusion drawn is that reaction rates with TZM were not nearly as great as they were with WC 103. Second, the total reaction between GaAs and WC 103 was almost twice that with TZM. Therefore, even though WC 103 is easier to fabricate, at least half of the cartridge thickness will be degraded if contact is made with one of the semiconductor materials leading to a loss of strength properties.

THE GRAVIMETRIC DETERMINATION OF MOLYBDENUM IN URANIUM-MOLYBDENUM ALLOYS

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1959-03-01

The sample is dissolved in nitric and hydrochloric acids. After heating the solution with sulfuric acid, molybodenum is precipitated as the benzoin-oxime complex which is ignited to molybdic oxide. This is dissolved in ammonia, and the molybdenum is precipitated and weighed as lead molybdate. (auth)

Capture of Tritium Released from Cladding in the Zirconium Recycle Process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spencer, Barry B.; Walker, T. B.; Bruffey, S. H.

2016-08-31

Zirconium may be recovered from the Zircaloy® cladding of used nuclear fuel (UNF) for recycle or to reduce the quantities of high-level waste destined for a geologic repository. Recovery of zirconium using a chlorination process is currently under development at the Oak Ridge National Laboratory. The approach is to treat the cladding with chlorine gas to convert the zirconium in the alloy (~98 wt % of the alloy mass) to zirconium tetrachloride. A significant fraction of the tritium (0–96%) produced in nuclear fuel during irradiation may be found in zirconium-based cladding and could be released from the cladding when themore » solid matrix is destroyed by the chlorination reaction. To prevent uncontrolled release of radioactive tritium to other parts of the plant or to the environment, a method to recover the tritium may be required. The focus of this effort was to (1) identify potential methods for the recovery of tritium from the off-gas of the zirconium recycle process, (2) perform scoping tests on selected recovery methods using nonradioactive gas simulants, and (3) select a process design appropriate for testing on radioactive gas streams generated by the engineering-scale zirconium recycle demonstrations on radioactive used cladding.« less

Improvement of wear resistance of plasma-sprayed molybdenum blend coatings

NASA Astrophysics Data System (ADS)

Ahn, Jeehoon; Hwang, Byoungchul; Lee, Sunghak

2005-06-01

The wear resistance of plasma sprayed molybdenum blend coatings applicable to synchronizer rings or piston rings was investigated in this study. Four spray powders, one of which was pure molybdenum and the others blended powders of bronze and aluminum-silicon alloy powders mixed with molybdenum powders, were sprayed on a low-carbon steel substrate by atmospheric plasma spraying. Microstructural analysis of the coatings showed that the phases formed during spraying were relatively homogeneously distributed in the molybdenum matrix. The wear test results revealed that the wear rate of all the coatings increased with increasing wear load and that the blended coatings exhibited better wear resistance than the pure molybdenum coating, although the hardness was lower. In the pure molybdenum coatings, splats were readily fractured, or cracks were initiated between splats under high wear loads, thereby leading to the decrease in wear resistance. On the other hand, the molybdenum coating blended with bronze and aluminum-silicon alloy powders exhibited excellent wear resistance because hard phases such as CuAl2 and Cu9Al4 formed inside the coating.

Reclamation of niobium compounds from ionic liquid electrochemical polishing of superconducting radio frequency cavities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wixtrom, Alex I.; Buhler, Jessica E.; Reece, Charles E.

2013-06-01

Recent research has shown that choline chloride (vitamin B4)-based solutions can be used as a greener alternative to acid-based electrochemical polishing solutions. This study demonstrated a successful method for electrochemical deposition of niobium compounds onto the surface of copper substrates using a novel choline chloride-based ionic liquid. Niobium ions present in the ionic liquid solution were dissolved into the solution prior to deposition via electrochemical polishing of solid niobium. A black coating was clearly visible on the surface of the Cu following deposition. This coating was analyzed using scanning electron microscopy (SEM), electron dispersive X-ray spectroscopy (EDX), atomic force microscopymore » (AFM), and X-ray fluorescence spectroscopy (XRF). This ionic liquid-based electrochemical deposition method effectively recycles previously dissolved niobium from electrochemical polishing of superconducting radio frequency (SRF) cavities.« less

Storage and Bioavailability of Molybdenum in Soils Increased by Organic Matter Complexation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wichard, T.; Mishra, B; Myneni, S

2009-01-01

The micronutrient molybdenum is a necessary component of the nitrogen-fixing enzyme nitrogenase1, 2. Molybdenum is very rare in soils, and is usually present in a highly soluble form, making it susceptible to leaching3, 4. However, it is generally thought that molybdenum attaches to mineral surfaces in acidic soils; this would prevent its escape into the groundwater, but would also impede uptake by microbes3. Here we use X-ray spectroscopy to examine the chemical speciation of molybdenum in soil samples from forests in Arizona and New Jersey. We show that in the leaf litter layer, most of the molybdenum forms strong complexesmore » with plant-derived tannins and tannin-like compounds; molybdenum binds to these organic ligands across a wide pH range. In deeper soils, molybdenum binds to both iron oxides and natural organic matter. We suggest that the molybdenum bound to organic matter can be captured by small complexing agents that are released by nitrogen-fixing bacteria; the molybdenum can then be incorporated into nitrogenase. We conclude that the binding of molybdenum to natural organic matter helps prevent leaching of molybdenum, and is thus a critical step in securing new nitrogen in terrestrial ecosystems.« less

Niobium Solar Mobile Project — High Strength Niobium Microalloyed Steel as a Solution to Improve Electric Super Scooter and Motorcycle Performance

NASA Astrophysics Data System (ADS)

Richards, Terry; Kauppi, Erik; Flanagan, Lauren; Ribeio, Eduardo A. A. G.; Nogueira, Marcos A. Stuart; McCourtney, Ian

This paper presents the advantages of replacing mild steel with high strength niobium microalloyed steel in the structure of Electric Super Scooters, Electric Cargo Motorcycles and Solar Charging Stations. The Mini-Fleet-in-a-Box concept was developed by Current Motor to guarantee mobility, efficiency and solar generated electricity. With the adoption of niobium microalloyed high strength steel for more than 90% of the Super Scooter and Motorcycle structures, it was possible to redesign the frame, resulting in a 31% weight reduction and a very modern and functional body. Together with a new powertrain, these changes were responsible for increasing Motorcycle autonomy by more than 15%, depending on average speed. The new frame design reduced the number of high strain points in the frame, increasing the safety of the project. The Solar Charging Station was built using the container concept and designed with high strength niobium microalloyed steel, which resulted in a weight reduction of 25%. CBMM's facility in Araxá, Brazil was selected in the second half of 2013 as the demonstration site to test the efficiency of the Super Scooter and Solar Charging Station. Each Super Scooter has run more than 2,000 km maintenance-free with an autonomy of more than 100 km per charge.

METHOD OF IMPROVING CORROSION RESISTANCE OF ZIRCONIUM

DOEpatents

Shannon, D.W.

1961-03-28

An improved intermediate rinse for zirconium counteracts an anomalous deposit that often results in crevices and outof-the-way places when ordinary water is used to rinse away a strong fluoride etching solution designed to promote passivation of the metal. The intermediate rinse, which is used after the etching solution and before the water, is characterized by a complexing agent for fluoride ions such as aluminum or zirconium nitrates or chlorides.

Effects of niobium additions on the structure, depth, and austenite grain size of the case of carburized 0.07% C steels

NASA Astrophysics Data System (ADS)

Islam, M. A.; Bepari, M. M. A.

1996-10-01

Carbon (0.07%) steel samples containing about 0.04% Nb singly and in combination with nitrogen were carburized in a natural Titas gas atmosphere at a temperature of 1223 K (950 °C) and a pressure of about 0.10 MPa for 1/2 to 4 h, followed by slow cooling in the furnace. Their microstructures were studied by optical microscopy. The austenite grain size of the case and the case depths were determined on baseline samples of low-carbon steels and also on niobium and (Nb + N) microalloyed steel samples. It was found that, when compared to the baseline steel, niobium alone or in combination with nitrogen decreased the thickness of cementite network near the surface of the carburized case of the steels. However, niobium in combination with nitrogen was more effective than niobium in reducing the thickness of cementite network. Niobium with or without nitrogen inhibited the formation of Widmanstätten cementite plates at grain boundaries and within the grains near the surface in the hypereutectoid zone of the case. It was also revealed that, when compared to the baseline steel, niobium decreased the case depth of the carburized steels, but that niobium with nitrogen is more effective than niobium alone in reducing the case depth. Niobium as niobium carbide (NbC) and niobium in the presence of nitrogen as niobium carbonitride, [Nb(C,N)] particles refined the austenite grain size of the carburized case, but Nb(C,N) was more effective than NbC in inhibiting austenite grain growth.

40 CFR 471.90 - Applicability; description of the zirconium-hafnium forming subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... zirconium-hafnium forming subcategory. 471.90 Section 471.90 Protection of Environment ENVIRONMENTAL... POINT SOURCE CATEGORY Zirconium-Hafnium Forming Subcategory § 471.90 Applicability; description of the zirconium-hafnium forming subcategory. This subpart applies to discharges of pollutants to waters of the...

Method of low tantalum amounts determination in niobium and its compounds by ICP-OES technique.

PubMed

Smolik, Marek; Turkowska, Magdalena

2013-10-15

A method of determination of low amounts of tantalum in niobium and niobium compounds without its prior separation by means of inductively coupled plasma optical emission spectrometry (ICP-OES) has been worked out. The method involves dissolution of the analyzed samples of niobium as well as its various compounds (oxides, fluorides, chlorides, niobates(V)) in fluoride environments, precipitation of sparingly soluble niobic(tantalic) acid (Nb2O5(Ta2O5) · xH2O), converting them into soluble complex compounds by means of oxalic acid with addition of hydrogen peroxide and finally analyzing directly obtained solutions by ICP-OES. This method permits determination of Ta in niobium at the level of 10(-3)% with relatively good precision (≤ 8% RSD) and accuracy (recovery factor: 0.9-1.1). Relative differences in the results obtained by two independent methods (ICP-OES and ICP-MS) do not exceed 14%, and other elements present in niobium compounds (Ti, W, Zr, Hf, V, Mo, Fe, Cr) at the level of 10(-2)% do not affect determination. © 2013 Elsevier B.V. All rights reserved.

Zirconium determination by cooling curve analysis during the pyroprocessing of used nuclear fuel

NASA Astrophysics Data System (ADS)

Westphal, B. R.; Price, J. C.; Bateman, K. J.; Marsden, K. C.

2015-02-01

An alternative method to sampling and chemical analyses has been developed to monitor the concentration of zirconium in real-time during the casting of uranium products from the pyroprocessing of used nuclear fuel. The method utilizes the solidification characteristics of the uranium products to determine zirconium levels based on standard cooling curve analyses and established binary phase diagram data. Numerous uranium products have been analyzed for their zirconium content and compared against measured zirconium data. From this data, the following equation was derived for the zirconium content of uranium products:

Direct synthesis of zirconium powder by magnesium reduction

NASA Astrophysics Data System (ADS)

Lee, Dong-Won; Yun, Jung-Yeul; Yoon, Sung-Won; Wang, Jei-Pil

2013-05-01

The direct synthesis of zirconium powder has been conducted through an analysis of the chemical reaction between evaporated ZrCl4 and molten magnesium over a range of reduction temperatures, concentration of hydrochloric acid, and stirring time. The observed results indicated that the purity of zirconium powder increased with increased stirring time, and Mg and MgCl2 were removed by 10 wt% of hydrochloric acid solution. The pure zirconium powder was obtained by stirring again for 5 h using 5 wt% of hydrochloric acid solution. It was noted that the mean particle size increased when the reaction temperature was increased, and the size of the powder at 1,123 K and 1,173 K was found to be 10 μm and 15 μm, respectively. In addition, the purity of the powder was also improved with temperature, and its purity finally reached up to 99.5% at 1,250 K. Overall, pure zirconium powder was obtained after a stirring stage for 5 hours using 5 wt% of hydrochloric acid solution.

Nuclear-grade zirconium prepared by combining combustion synthesis with molten-salt electrorefining technique

NASA Astrophysics Data System (ADS)

Li, Hui; Nersisyan, Hayk H.; Park, Kyung-Tae; Park, Sung-Bin; Kim, Jeong-Guk; Lee, Jeong-Min; Lee, Jong-Hyeon

2011-06-01

Zirconium has a low absorption cross-section for neutrons, which makes it an ideal material for use in nuclear reactor applications. However, hafnium typically contained in zirconium causes it to be far less useful for nuclear reactor materials because of its high neutron-absorbing properties. In the present study, a novel effective method has been developed for the production of hafnium-free zirconium. The process includes two main stages: magnesio-thermic reduction of ZrSiO 4 under a combustion mode, to produce zirconium silicide (ZrSi), and recovery of hafnium-free zirconium by molten-salt electrorefining. It was found that, depending on the electrorefining procedure, it is possible to produce zirconium powder with a low hafnium content: 70 ppm, determined by ICP-AES analysis.

Biosynthesis of the Iron-Molybdenum Cofactor of Nitrogenase*

PubMed Central

Hu, Yilin; Ribbe, Markus W.

2013-01-01

The iron-molybdenum cofactor (the M-cluster) serves as the active site of molybdenum nitrogenase. Arguably one of the most complex metal cofactors in biological systems, the M-cluster is assembled through the formation of an 8Fe core prior to the insertion of molybdenum and homocitrate into this core. Here, we review the recent progress in the research area of M-cluster assembly, with an emphasis on our work that provides useful insights into the mechanistic details of this process. PMID:23539617

Publications - SR 41 | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

; Mercury; Minerals; Minerals Report; Mining; Mining Methods; Molybdenum; Nickel; Niobium; Peat; Platinum ; Production Data; Radioactive Minerals; Resource Assessment; Sand and Gravel; Silver; Soapstone; Tantalum

Capture of Tritium Released from Cladding in the Zirconium Recycle Process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spencer, Barry B.; Walker, T. B.; Bruffey, Stephanie H.

2016-08-31

This report is issued as the first revision to FCRD-MRWFD-2016-000297. Zirconium may be recovered from the Zircaloy® cladding of used nuclear fuel (UNF) for recycle or to reduce the quantities of high-level waste destined for a geologic repository. Recovery of zirconium using a chlorination process is currently under development at the Oak Ridge National Laboratory. The approach is to treat the cladding with chlorine gas to convert the zirconium in the alloy (~98 wt % of the alloy mass) to zirconium tetrachloride. A significant fraction of the tritium (0–96%) produced in nuclear fuel during irradiation may be found in zirconium-basedmore » cladding and could be released from the cladding when the solid matrix is destroyed by the chlorination reaction. To prevent uncontrolled release of radioactive tritium to other parts of the plant or to the environment, a method to recover the tritium may be required. The focus of this effort was to (1) identify potential methods for the recovery of tritium from the off-gas of the zirconium recycle process, (2) perform scoping tests on selected recovery methods using non-radioactive gas simulants, and (3) select a process design appropriate for testing on radioactive gas streams generated by the engineering-scale zirconium recycle demonstrations on radioactive used cladding.« less

Niobium-aluminum base alloys having improved, high temperature oxidation resistance

NASA Technical Reports Server (NTRS)

Hebsur, Mohan G. (Inventor); Stephens, Joseph R. (Inventor)

1991-01-01

A niobium-aluminum base alloy having improved oxidation resistance at high temperatures and consisting essentially of 48%-52% niobium, 36%-42% aluminum, 4%-10% chromium, 0%-2%, more preferably 1%-2%, silicon and/or tungsten with tungsten being preferred, and 0.1%-2.0% of a rare earth selected from the group consisting of yttrium, ytterbium and erbium. Parabolic oxidation rates, k.sub.p, at 1200.degree. C. range from about 0.006 to 0.032 (mg/cm.sup.2).sup.2 /hr. The new alloys also exhibit excellent cyclic oxidation resistance.

Qualification of niobium materials for superconducting radio frequency cavity applications: View of a condensed matter physicist

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roy, S. B., E-mail: sbroy@rrcat.gov.in; Myneni, G. R., E-mail: rao@jlab.org

2015-12-04

We address the issue of qualifications of the niobium materials to be used for superconducting radio frequency (SCRF) cavity fabrications, from the point of view of a condensed matter physicist/materials scientist. We focus on the particular materials properties of niobium required for the functioning a SCRF cavity, and how to optimize the same properties for the best SCRF cavity performance in a reproducible manner. In this way the niobium materials will not necessarily be characterized by their purity alone, but in terms of those materials properties, which will define the limit of the SCRF cavity performance and also other relatedmore » material properties, which will help to sustain this best SCRF cavity performance. Furthermore we point out the need of standardization of the post fabrication processing of the niobium-SCRF cavities, which does not impair the optimized superconducting and thermal properties of the starting niobium-materials required for the reproducible performance of the SCRF cavities according to the design values.« less

40 CFR 721.10598 - Lead strontium titanium zirconium oxide.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Lead strontium titanium zirconium... Specific Chemical Substances § 721.10598 Lead strontium titanium zirconium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as lead strontium...

40 CFR 721.10598 - Lead strontium titanium zirconium oxide.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Lead strontium titanium zirconium... Specific Chemical Substances § 721.10598 Lead strontium titanium zirconium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as lead strontium...

Fluorometric determination of zirconium in minerals

USGS Publications Warehouse

Alford, W.C.; Shapiro, L.; White, C.E.

1951-01-01

The increasing use of zirconium in alloys and in the ceramics industry has created renewed interest in methods for its determination. It is a common constituent of many minerals, but is usually present in very small amounts. Published methods tend to be tedious, time-consuming, and uncertain as to accuracy. A new fluorometric procedure, which overcomes these objections to a large extent, is based on the blue fluorescence given by zirconium and flavonol in sulfuric acid solution. Hafnium is the only element that interferes. The sample is fused with borax glass and sodium carbonate and extracted with water. The residue is dissolved in sulfuric acid, made alkaline with sodium hydroxide to separate aluminum, and filtered. The precipitate is dissolved in sulfuric acid and electrolysed in a Melaven cell to remove iron. Flavonol is then added and the fluorescence intensity is measured with a photo-fluorometer. Analysis of seven standard mineral samples shows excellent results. The method is especially useful for minerals containing less than 0.25% zirconium oxide.

Effect of interstitial impurities on the field dependent microwave surface resistance of niobium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martinello, M., E-mail: mmartine@fnal.gov; Checchin, M.; Department of Physics, Illinois Institute of Technology, Chicago, Illinois 60616

Previous work has demonstrated that the radio frequency surface resistance of niobium resonators is dramatically reduced when nitrogen impurities are dissolved as interstitial in the material. This effect is attributed to the lowering of the Mattis-Bardeen surface resistance with increasing accelerating field; however, the microscopic origin of this phenomenon is poorly understood. Meanwhile, an enhancement of the sensitivity to trapped magnetic field is typically observed for such cavities. In this paper, we conduct a systematic study on these different components contributing to the total surface resistance as a function of different levels of dissolved nitrogen, in comparison with standard surfacemore » treatments for niobium resonators. Adding these results together, we are able to show which is the optimum surface treatment that maximizes the Q-factor of superconducting niobium resonators as a function of expected trapped magnetic field in the cavity walls. These results also provide insights on the physics behind the change in the field dependence of the Mattis-Bardeen surface resistance, and of the trapped magnetic vortex induced losses in superconducting niobium resonators.« less

NEUTRON REACTOR FUEL ELEMENT UTILIZING ZIRCONIUM-BASE ALLOYS

DOEpatents

Saller, H.A.; Keeler, J.R.; Szumachowski, E.R.

1957-11-12

This patent relates to clad fuel elements for use in neutronic reactors and is drawn to such a fuel element which consists of a core of fissionable material, comprised of an alloy of zirconium and U/sup 235/ enriched uranium, encased in a jacket of a binary zirconium-tin alloy in which the tin content ranges between 1 and 15% by weight.

Standard Method for Analyzing Gases in Titanium and Titanium Alloys. Standard Method for the Chemical Analysis of Titanium Alloys.

DTIC Science & Technology

1982-10-28

form a non- soluble complex. After filtering and burning the non-pure molybdenum trioxide is weighed. Ammonia water is used to dissolve the molybdenum...niobium and tantalum should use the methyl alcohol distillation - curcumin absorption luminosity 66 method for determination. II. The Methyl Alcohol...Distillation - Curcumin Absorption Luminosity Method 1. Summary of Method In a phosphorus sulfate medium, boron and methyl alcohol produce methyl borate

Low activation ferritic alloys

DOEpatents

Gelles, David S.; Ghoniem, Nasr M.; Powell, Roger W.

1986-01-01

Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

Low activation ferritic alloys

DOEpatents

Gelles, D.S.; Ghoniem, N.M.; Powell, R.W.

1985-02-07

Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

The Quantitative Microstructural Characterization of Multipass TIG Ultra Low Carbon Bainitic Steel Weldments and Correlation with Mechanical Properties

DTIC Science & Technology

1993-09-01

in TIG weldments. The alloying elements used in ULCB steels are; Carbon (C), Manganese (Mn), Molybdenum (Mo), Nickel (Ni), Niobium (Nb), Chromium (Cr...process. 7 C. WELDING PROCESSES 1. Tungsten Inert Gas (TIG) Welding Tungsten Inert Gas (TIG) Welding (or Gas Tungsten Arc Welding ( GTAW )), produces... chromium (Cr), molybdenum (Mo), and sometimes vanadium (V). Reheat cracking occurs in the HAZ during postweld stress relieving, especially in thick

Geologic structure of Gofitsky deposit of titanium and zirconium and perspectives of the reserve base of titanium and zirconium in Russia

NASA Astrophysics Data System (ADS)

Kukhmazov, Iskander

2016-04-01

With the fall of the Soviet Union, all the mining deposits of titanium and zirconium appeared outside of Russian Federation. Therefore the studying of deposits of titanium and zirconium in Russia is very important nowadays. There is a paradoxical situation in the country: in spite of possible existence of national mineral resource base of Ti-Zr material, which can cover needs of the country, Russia is the one of the largest buyers of imported Ti-Zr material in the world. Many deposits are not mined, and those which are in the process of mining have poor reserves. Demand for this raw material is very great not only for Russia, but also for the world in general. Today there is a scarcity of zircon around the world and it will only increase through time. Therefore prices of products of titanium and zirconium also increase. Consequently Russian deposits of titanium and zirconium with higher content than foreign may become competitive. Russia is forced to buy raw materials (zirconium and titanium production) from former Soviet Union countries at prices higher than the world's and thus incur huge losses, including customs charges. Russia should create its own mineral resource base of Ti-Zr. Studied titanium-zirconium deposits of Stavropol region may become the basis for the south part of Russia. At first, Beshpagirsky deposit should be pointed out. It has large reserves of ore sands with high content of Ti-Zr. A combination of favorable geographical position of the area with developed industrial infrastructure makes it very beneficial as an object for high priority development. Gofitsky deposit should be pointed out as well. Its sands have a wide areal distribution and a high content of titanium and zirconium. Chokrak, Karagan-Konksk and Sarmatian sediments of the Miocene of Gofitsky deposit are productive for titanium and zirconium placers within Stavropol region of Russia. Gofitsky deposit was evaluated from financial and economic point of view and the following data

Electrochemical Deposition of Niobium onto the Surface of Copper Using a Novel Choline Chloride-Based Ionic Liquid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wixtroma, Alex I.; Buhlera, Jessica E.; Reece, Charles E.

2013-06-01

Recent research has shown that choline chloride-based solutions can be used to replace acid-based electrochemical polishing solutions. In this study niobium metal was successfully deposited on the surface of copper substrate via electrochemical deposition using a novel choline chloride-based ionic liquid. The niobium metal used for deposition on the Cu had been dissolved in the solution from electrochemical polishing of a solid niobium piece prior to the deposition. The visible coating on the surface of the Cu was analyzed using scanning electron microscopy (SEM) and electron dispersive x-ray spectroscopy (EDX). This deposition method effectively recycles previously dissolved niobium from electrochemicalmore » polishing.« less

METHOD OF PREPARING SINTERED ZIRCONIUM METAL FROM ITS HYDRIDES

DOEpatents

Angier, R.P.

1958-02-11

The invention relates to the preparation of metal shapes from zirconium hydride by powder metallurgical techniques. The zirconium hydride powder which is to be used for this purpose can be prepared by rendering massive pieces of crystal bar zirconium friable by heat treatment in purified hydrogen. This any then be ground into powder and powder can be handled in the air without danger of it igniting. It may then be compacted in the normal manner by being piaced in a die. The compact is sintered under vacuum conditions preferably at a temperature ranging from 1200 to 1300 deg C and for periods of one to three hours.

Ultrathin niobium nanofilms on fiber optical tapers - a new route towards low-loss hybrid plasmonic modes

NASA Astrophysics Data System (ADS)

Wieduwilt, Torsten; Tuniz, Alessandro; Linzen, Sven; Goerke, Sebastian; Dellith, Jan; Hübner, Uwe; Schmidt, Markus A.

2015-11-01

Due to the ongoing improvement in nanostructuring technology, ultrathin metallic nanofilms have recently gained substantial attention in plasmonics, e.g. as building blocks of metasurfaces. Typically, noble metals such as silver or gold are the materials of choice, due to their excellent optical properties, however they also possess some intrinsic disadvantages. Here, we introduce niobium nanofilms (~10 nm thickness) as an alternate plasmonic platform. We demonstrate functionality by depositing a niobium nanofilm on a plasmonic fiber taper, and observe a dielectric-loaded niobium surface-plasmon excitation for the first time, with a modal attenuation of only 3-4 dB/mm in aqueous environment and a refractive index sensitivity up to 15 μm/RIU if the analyte index exceeds 1.42. We show that the niobium nanofilm possesses bulk optical properties, is continuous, homogenous, and inert against any environmental influence, thus possessing several superior properties compared to noble metal nanofilms. These results demonstrate that ultrathin niobium nanofilms can serve as a new platform for biomedical diagnostics, superconducting photonics, ultrathin metasurfaces or new types of optoelectronic devices.

Buffered Electrochemical Polishing of Niobium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gianluigi Ciovati; Tian, Hui; Corcoran, Sean

The standard preparation of superconducting radio-frequency (SRF) cavities made of pure niobium include the removal of a 'damaged' surface layer, by buffered chemical polishing (BCP) or electropolishing (EP), after the cavities are formed. The performance of the cavities is characterized by a sharp degradation of the quality factor when the surface magnetic field exceeds about 90 mT, a phenomenon referred to as 'Q-drop.' In cavities made of polycrystalline fine grain (ASTM 5) niobium, the Q-drop can be significantly reduced by a low-temperature (? 120 °C) 'in-situ' baking of the cavity if the chemical treatment was EP rather than BCP. Asmore » part of the effort to understand this phenomenon, we investigated the effect of introducing a polarization potential during buffered chemical polishing, creating a process which is between the standard BCP and EP. While preliminary results on the application of this process to Nb cavities have been previously reported, in this contribution we focus on the characterization of this novel electrochemical process by measuring polarization curves, etching rates, surface finish, electrochemical impedance and the effects of temperature and electrolyte composition. In particular, it is shown that the anodic potential of Nb during BCP reduces the etching rate and improves the surface finish.« less

Computational Design of a Novel Medium-Carbon, Low-Alloy Steel Microalloyed with Niobium

NASA Astrophysics Data System (ADS)

Javaheri, Vahid; Nyyssönen, Tuomo; Grande, Bjørnar; Porter, David

2018-04-01

The design of a new steel with specific properties is always challenging owing to the complex interactions of many variables. In this work, this challenge is dealt with by combining metallurgical principles with computational thermodynamics and kinetics to design a novel steel composition suitable for thermomechanical processing and induction heat treatment to achieve a hardness level in excess of 600 HV with the potential for good fracture toughness. CALPHAD-based packages for the thermodynamics and kinetics of phase transformations and diffusion, namely Thermo-Calc® and JMatPro®, have been combined with an interdendritic segregation tool (IDS) to optimize the contents of chromium, molybdenum and niobium in a proposed medium-carbon low-manganese steel composition. Important factors taken into account in the modeling and optimization were hardenability and as-quenched hardness, grain refinement and alloying cost. For further investigations and verification, the designed composition, i.e., in wt.% 0.40C, 0.20Si, 0.25Mn, 0.90Cr, 0.50Mo, was cast with two nominal levels of Nb: 0 and 0.012 wt.%. The results showed that an addition of Nb decreases the austenite grain size during casting and after slab reheating prior to hot rolling. Validation experiments showed that the predicted properties, i.e., hardness, hardenability and level of segregation, for the designed composition were realistic. It is also demonstrated that the applied procedure could be useful in reducing the number of experiments required for developing compositions for other new steels.

Mechanical resistance of zirconium implant abutments: A review of the literature

PubMed Central

Vaquero-Aguilar, Cristina; Torres-Lagares, Daniel; Jiménez-Melendo, Manuel; Gutiérrez-Pérez, José L.

2012-01-01

The increase of aesthetic demands, together with the successful outcome of current implants, has renewed interest in the search for new materials with enough mechanical properties and better aesthetic qualities than the materials customarily used in implanto-prosthetic rehabilitation. Among these materials, zirconium has been used in different types of implants, including prosthetic abutments. The aim of the present review is to analyse current scientific evidence supporting the use of this material for the above mentioned purposes. We carried out the review of the literature published in the last ten years (2000 through 2010) of in vitro trials of dynamic and static loading of zirconium abutments found in the databases of Medline and Cochrane using the key words zirconium abutment, fracture resistance, fracture strength, cyclic loading. Although we have found a wide variability of values among the different studies, abutments show favourable clinical behaviour for the rehabilitation of single implants in the anterior area. Such variability may be explained by the difficulty to simulate daily mastication under in vitro conditions. The clinical evidence, as found in our study, does not recommend the use of implanto-prosthetic zirconium abutments in the molar area. Key words: Zirconium abutment, zirconium implant abutment, zirconia abutment, fracture resistance, fracture strength, cyclic loading. PMID:22143702

Microstructure evolution and tensile properties of Zr-2.5 wt.% Nb pressure tubes processed from billets with different microstructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kapoor, K.; Saratchandran, N.; Muralidharan, K.

1999-02-01

Pressurized heavy water reactors (PHWR) use zirconium-base alloys for their low neutron-absorption cross section, good mechanical strength, low irradiation creep, and high corrosion resistance in reactor atmospheres. Starting with identical ingots, billets having different microstructures were obtained by three different processing methods for fabrication of Zr-2.5 wt%Nb pressure tubes., The billets were further processed by hot extrusion and cold Pilger tube reducing to the finished product. Microstructural characterization was done at each stage of processing. The effects of the initial billet microstructure on the intermediate and final microstructure and mechanical property results were determined. It was found that the structuremore » at each stage and the final mechanical properties depend strongly on the initial billet microstructure. The structure at the final stage consists of elongated alpha zirconium grains with a network of metastable beta zirconium phase. Some of this metastable phase transforms into stable beta niobium during thermomechanical processing. Billets with quenched structure resulted in less beta niobium at the final stage. The air cooled billets resulted in a large amount of beta niobium. The tensile properties, especially the percentage elongation, were found to vary for the different methods. Higher percentage elongation was observed for billets having quenched structure. Extrusion and forging did not produce any characteristic differences in the properties. The results were used to select a process flow sheet which yields the desired mechanical properties with suitable microstructure in the final product.« less

40 CFR 421.330 - Applicability: Description of the primary zirconium and hafnium subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... primary zirconium and hafnium subcategory. 421.330 Section 421.330 Protection of Environment ENVIRONMENTAL... CATEGORY Primary Zirconium and Hafnium Subcategory § 421.330 Applicability: Description of the primary zirconium and hafnium subcategory. The provisions of this subpart are applicable to discharges resulting...

Understanding Quality Factor Degradation in Superconducting Niobium Cavities at Low Microwave Field Amplitudes

DOE PAGES

Romanenko, A.; Schuster, D. I.

2017-12-28

In niobium superconducting radio frequency (SRF) cavities for particle acceleration, a decrease of the quality factor at lower fields—a so-called low field Q slope or LFQS—has been a long-standing unexplained effect. By extending the high Q measurement techniques to ultralow fields, we discover two previously unknown features of the effect: (i) saturation at rf fields lower than E acc~0.1 MV/m; (ii) strong degradation enhancement by growing thicker niobium pentoxide. Our findings suggest that the LFQS may be caused by the two level systems in the natural niobium oxide on the inner cavity surface, thereby identifying a new source of residual resistance andmore » providing guidance for potential nonaccelerator low-field applications of SRF cavities.« less

Understanding Quality Factor Degradation in Superconducting Niobium Cavities at Low Microwave Field Amplitudes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Romanenko, A.; Schuster, D. I.

In niobium superconducting radio frequency (SRF) cavities for particle acceleration, a decrease of the quality factor at lower fields—a so-called low field Q slope or LFQS—has been a long-standing unexplained effect. By extending the high Q measurement techniques to ultralow fields, we discover two previously unknown features of the effect: (i) saturation at rf fields lower than E acc~0.1 MV/m; (ii) strong degradation enhancement by growing thicker niobium pentoxide. Our findings suggest that the LFQS may be caused by the two level systems in the natural niobium oxide on the inner cavity surface, thereby identifying a new source of residual resistance andmore » providing guidance for potential nonaccelerator low-field applications of SRF cavities.« less

Molybdenum Valence in Basaltic Silicate Melts

NASA Technical Reports Server (NTRS)

Danielson, L. R.; Righter, K.; Newville, M.; Sutton, S.; Pando, K.

2010-01-01

The moderately siderophile element molybdenum has been used as an indicator in planetary differentiation processes, and is particularly relevant to core formation [for example, 1-6]. However, models that apply experimental data to an equilibrium differentiation scenario infer the oxidation state of molybdenum from solubility data or from multivariable coefficients from metal-silicate partitioning data [1,3,7]. Partitioning behavior of molybdenum, a multivalent element with a transition near the J02 of interest for core formation (IW-2) will be sensitive to changes in JO2 of the system and silicate melt structure. In a silicate melt, Mo can occur in either 4+ or 6+ valence state, and Mo6+ can be either octahedrally or tetrahedrally coordinated. Here we present first XANES measurements of Mo valence in basaltic run products at a range of P, T, and JO2 and further quantify the valence transition of Mo.

Molybdenum In Cathodes Of Sodium/Metal Chloride Cells

NASA Technical Reports Server (NTRS)

Bugga, Ratnakumar V.; Attia, Alan I.; Halpert, Gerald

1992-01-01

Cyclic voltammetric curves of molybdenum wire in NaAlCl4 melt indicate molybdenum chloride useful as cathode material in rechargeable sodium/metal chloride electrochemical cells. Batteries used in electric vehicles, for electric-power load leveling, and other applications involving high energy and power densities.

Equilibrium of molybdenum in selected extraction systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tkac, Peter; Paulenova, Alena

2007-07-01

The concentration of molybdenum(VI) in dissolved irradiated nuclear fuel is comparable with the concentrations of Tc, Am and Np. Therefore it is of big interest to understand its behavior under conditions related to the UREX/TRUEX process. The effect of the poly-speciation of molybdenum in aqueous solution on its extraction by neutral solvents TBP and CMPO/TBP was studied. Extraction yields of molybdenum decreased significantly when AHA was added to aqueous phase. Our investigation confirmed a strong ability of the aceto-hydroxamic acid to form complexes with Mo in high acidic solutions. Spectroscopic data (UV-Vis) confirmed that a fraction of the Mo(VI)-AHA complexmore » is present in the organic phase after extraction. (authors)« less

Thermochemistry of amorphous and crystalline zirconium and hafnium silicates.

NASA Astrophysics Data System (ADS)

Ushakov, S.; Brown, C. E.; Navrotsky, Alexandra; Boatner, L. A.; Demkov, A. A.; Wang, C.; Nguyen, B.-Y.

2003-03-01

Calorimetric investigation of amorphous and crystalline zirconium and hafnium silicates was performed as part of a research program on thermochemistry of alternative gate dielectrics. Amorphous hafnium and zirconium silicates with varying SiO2 content were synthesized by a sol-gel process. Crystalline zirconium and hafnium silicates (zircon and hafnon) were synthesized by solid state reaction at 1450 °C from amorphous gels and grown as single crystals from flux. High temperature oxide melt solution calorimetry in lead borate (2PbO.B2O3) solvent at 800 oC was used to measure drop solution enthalpies for amorphous and crystalline zirconium and hafnium silicates and corresponding oxides. Applying appropriate thermochemical cycles, formation enthalpy of crystalline ZrSiO4 (zircon) from binary oxides (baddeleite and quartz) at 298 K was calculated as -23 +/-2 kJ/mol and enthalpy difference between amorphous and crystalline zirconium silicate (vitrification enthalpy) was found to be 61 +/-3 kJ/mol. Crystallization onset temperatures of amorphous zirconium and hafnium silicates, as measured by differential scanning calorimetry (DSC), increased with silica content. The resulting crystalline phases, as characterized by X-ray diffraction (XRD), were tetragonal HfO2 and ZrO2. Critical crystallite size for tetragonal to monoclinic transformation of HfO2 in the gel was estimated as 6 +/-2 nm from XRD data Crystallization enthalpies per mole of hafnia and zirconia in gels decrease slightly together with crystallite size with increasing silica content, for example from -22 to -15 +/-1 kJ per mol of HfO2 crystallized at 740 and 1006 °C from silicates with 10 and 70 mol Applications of thermal analyses and solution calorimetry techniques together with first-principles density functional calculations to estimate interface and surface energies are discussed.

[The clinical application of zirconium-dioxide-ceramics. Case report].

PubMed

Somfai, Dóra; Zsigmond, Ágnes; Károlyházy, Katalin; Kispély, Barbara; Hermann, Péter

2015-12-01

Due to its outstanding physical, mechanical and esthetic properties, zirconium-dioxide is one of the most popular non-metal denture, capable of surpassing PFM in most cases. The recent advances of CAD/CAM technology makes it a good alternitve. Here we show the usefulness of zirconium-dioxide in everyday dental practice through three case reports.

Delta Niobium or Delta VICE?

NASA Astrophysics Data System (ADS)

Hofmann, A. W.

2006-12-01

Delta Niobium or Delta VICE? Niobium is one of a few chemical elements that can be used to discriminate between melts derived from upwelling mantle, represented by MORBs and OIBs, and those derived from subduction and continental crust environments. The Nb/U ratio was introduced because these two elements appear to partition nearly identically in upwelling environments, but very differently (from one another) in subduction and continental environments (Hofmann et al., 1986). Fitton et al. (1997, 2003) have taken a radically different approach, using log(Nb/Y)-log(Zr/Y) correlations that appear to discriminate between MORB and OIB (or plume) environments. MORB correlations are parallel to, and at lower Nb/Y ratios than, Iceland basalt correlations. This is expressed by a discrimination parameter defined as Delta Nb = 1.74 + log(Nb/Y) - 1.92 log(Zr/Y). N-MORB have negative Delta-Nb values, whereas Iceland and other OIBs have positive values. Fitton et al. interpret this in terms of a niobium deficiency in MORB that is balanced by a Nb excess in OIBs. This interpretation conflicts with evidence based on Nb/U ratios (Hofmann et al., 1986), that MORB and OIB are parts of a common reservoir, which is different from, and complementary to, the continental crust. Both parts of this MORB-OIB reservoir are characterized by higher-than-primitive Nb/U and Nb/Th ratios, whereas continental crust has dramatically lower Nb/U and Nb/Th ratios. The use of VICE/MICE (very-incompatible- element to moderately-incompatible-element) ratios, such as Nb/Y, obscures this. The significance of the VICE/MICE plot becomes clear if one replaces Nb by other VICEs in the log(Nb/Y)-log(Zr/Y) plot. This shows that any of these VICEs yield similar topologies as Nb/Y. Thus for a given Zr/Y ratio, depleted MORB have consistently lower Ba/Y, Th/Y, and La/Y ratios than do Iceland basalts, even the most incompatible-element- depleted Iceland picrites. This is caused by a less extreme depletion of

Overcoming the crystallization and designability issues in the ultrastable zirconium phosphonate framework system

DOE PAGES

Zheng, Tao; Yang, Zaixing; Gui, Daxiang; ...

2017-05-30

Metal-organic frameworks (MOFs) based on zirconium phosphonates exhibit superior chemical stability suitable for applications under harsh conditions. These compounds mostly exist as poorly crystallized precipitates, and precise structural information has therefore remained elusive. Furthermore, a zero-dimensional zirconium phosphonate cluster acting as secondary building unit has been lacking, leading to poor designability in this system. We overcome these challenges and obtain single crystals of three zirconium phosphonates that are suitable for structural analysis. Furthermore, these compounds are built by previously unknown isolated zirconium phosphonate clusters and exhibit combined high porosity and ultrastability even in fuming acids. SZ-2 possesses the largest voidmore » volume recorded in zirconium phosphonates and SZ-3 represents the most porous crystalline zirconium phosphonate and the only porous MOF material reported to survive in aqua regia. SZ-2 and SZ-3 can effectively remove uranyl ions from aqueous solutions over a wide pH range, and we have elucidated the removal mechanism.« less

Comparison of Zirconium Phosphonate-Modified Surfaces for Immobilizing Phosphopeptides and Phosphate-Tagged Proteins.

PubMed

Forato, Florian; Liu, Hao; Benoit, Roland; Fayon, Franck; Charlier, Cathy; Fateh, Amina; Defontaine, Alain; Tellier, Charles; Talham, Daniel R; Queffélec, Clémence; Bujoli, Bruno

2016-06-07

Different routes for preparing zirconium phosphonate-modified surfaces for immobilizing biomolecular probes are compared. Two chemical-modification approaches were explored to form self-assembled monolayers on commercially available primary amine-functionalized slides, and the resulting surfaces were compared to well-characterized zirconium phosphonate monolayer-modified supports prepared using Langmuir-Blodgett methods. When using POCl3 as the amine phosphorylating agent followed by treatment with zirconyl chloride, the result was not a zirconium-phosphonate monolayer, as commonly assumed in the literature, but rather the process gives adsorbed zirconium oxide/hydroxide species and to a lower extent adsorbed zirconium phosphate and/or phosphonate. Reactions giving rise to these products were modeled in homogeneous-phase studies. Nevertheless, each of the three modified surfaces effectively immobilized phosphopeptides and phosphopeptide tags fused to an affinity protein. Unexpectedly, the zirconium oxide/hydroxide modified surface, formed by treating the amine-coated slides with POCl3/Zr(4+), afforded better immobilization of the peptides and proteins and efficient capture of their targets.

Overcoming the crystallization and designability issues in the ultrastable zirconium phosphonate framework system

PubMed Central

Zheng, Tao; Yang, Zaixing; Gui, Daxiang; Liu, Zhiyong; Wang, Xiangxiang; Dai, Xing; Liu, Shengtang; Zhang, Linjuan; Gao, Yang; Chen, Lanhua; Sheng, Daopeng; Wang, Yanlong; Diwu, Juan; Wang, Jianqiang; Zhou, Ruhong; Chai, Zhifang; Albrecht-Schmitt, Thomas E.; Wang, Shuao

2017-01-01

Metal-organic frameworks (MOFs) based on zirconium phosphonates exhibit superior chemical stability suitable for applications under harsh conditions. These compounds mostly exist as poorly crystallized precipitates, and precise structural information has therefore remained elusive. Furthermore, a zero-dimensional zirconium phosphonate cluster acting as secondary building unit has been lacking, leading to poor designability in this system. Herein, we overcome these challenges and obtain single crystals of three zirconium phosphonates that are suitable for structural analysis. These compounds are built by previously unknown isolated zirconium phosphonate clusters and exhibit combined high porosity and ultrastability even in fuming acids. SZ-2 possesses the largest void volume recorded in zirconium phosphonates and SZ-3 represents the most porous crystalline zirconium phosphonate and the only porous MOF material reported to survive in aqua regia. SZ-2 and SZ-3 can effectively remove uranyl ions from aqueous solutions over a wide pH range, and we have elucidated the removal mechanism. PMID:28555656

Overcoming the crystallization and designability issues in the ultrastable zirconium phosphonate framework system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Tao; Yang, Zaixing; Gui, Daxiang

Metal-organic frameworks (MOFs) based on zirconium phosphonates exhibit superior chemical stability suitable for applications under harsh conditions. These compounds mostly exist as poorly crystallized precipitates, and precise structural information has therefore remained elusive. Furthermore, a zero-dimensional zirconium phosphonate cluster acting as secondary building unit has been lacking, leading to poor designability in this system. We overcome these challenges and obtain single crystals of three zirconium phosphonates that are suitable for structural analysis. Furthermore, these compounds are built by previously unknown isolated zirconium phosphonate clusters and exhibit combined high porosity and ultrastability even in fuming acids. SZ-2 possesses the largest voidmore » volume recorded in zirconium phosphonates and SZ-3 represents the most porous crystalline zirconium phosphonate and the only porous MOF material reported to survive in aqua regia. SZ-2 and SZ-3 can effectively remove uranyl ions from aqueous solutions over a wide pH range, and we have elucidated the removal mechanism.« less

Zirconium diselenite microstructures, formation and mechanism

NASA Astrophysics Data System (ADS)

Naik, Chandan C.; Salker, A. V.

2018-04-01

In this work, a series of microstructures of zirconium diselenite (Zr(SeO3)2) has been prepared via a simple precipitation method at room temperature without adding any organic surfactants. Phase purity of the sample has been checked by X-ray Diffraction. From the SEM, FESEM, and TEM images spheroid nanoparticles to the starfish-like structure of zirconium diselenite are detected. The morphological evolution processes were investigated carefully following time-dependent experiments and a growth mechanism has been proposed. Two different crystal growth processes, the oriented attachment process accompanying the Ostwald ripening process were held responsible for the formation of a structure resembling starfish having four arms.

Process for electroless deposition of metals on zirconium materials

DOEpatents

Donaghy, Robert E.

1978-01-01

A process for the electroless deposition of a metal layer on an article comprised of zirconium or a zirconium alloy is disclosed. The article is activated in an aged aqueous solution comprising from about 10 to about 20 grams per liter ammonium bifluoride and from about 0.75 to about 2 grams per liter of sulfuric acid. The solution is aged by immersion of pickled zirconium in the solution for at least about 10 minutes. The loosely adhering film formed on the article in the activating step is removed and the article is contacted with an electroless plating solution containing the metal to be deposited on the article upon sufficient contact with the article.

Process for electrolytic deposition of metals on zirconium materials

DOEpatents

Donaghy, Robert E.

1979-01-30

A process for the electrolytic deposition of a metal layer on an article comprised of zirconium or a zirconium alloy is disclosed. The article is activated in an aged aqueous solution comprising from about 10 to about 20 grams per liter ammonium bifluoride and from about 0.75 to about 2 grams per liter of sulfuric acid. The solution is aged by immersion of pickled zirconium in the solution for at least about 10 minutes. The loosely adhering film formed on the article in the activating step is removed and the article is contacted with an electrolytic plating solution containing the metal to be deposited on the article in the presence of an electrode receiving current.

Apatite grown in niobium by two-step plasma electrolytic oxidation.

PubMed

Pereira, Bruno Leandro; Lepienski, Carlos Maurício; Mazzaro, Irineu; Kuromoto, Neide Kazue

2017-08-01

Plasma electrolytic oxidation (PEO) of niobium plates were done electrochemically in two steps with electrolytes containing phosphorous and calcium being observed the formation of crystalline apatite. All samples were submitted to a first step of PEO using an electrolyte containing phosphate ions. The second oxidization step was made using three different electrolytes. Some samples were oxidized by PEO in electrolyte containing calcium, while in other samples it was used two mixtures of phosphoric acid and calcium acetate monohydrate solutions. Three different surface layers were obtained. The morphology and chemical composition of the films were analyzed by scanning electronic microscopy (SEM), and energy dispersive spectroscopy (EDS) respectively. It was observed that all samples submitted to two-step oxidation shown porous surface and a calcium and phosphorus rich layer. Average surface roughness (Ra) was measured by a profilometer remaining in the sub-micrometric range. The contact angle by sessile drop technique, using 1μL of distilled water was performed with an optical goniometer. It was verified a higher hydrophilicity in all surfaces compared to the polished niobium. Orthorhombic Nb 2 O 5 was identified by XRD in the oxide layer. Crystalline apatite was identified by XRD in surfaces after the second oxidation made with the Ca-rich electrolyte and a mixture of an electrolyte richer in Ca compared to P. These results indicate that a two-step oxidized niobium surface present great features for applications in the osseointegration processes: favorable chemical composition that increase the biocompatibility, the formation of crystalline niobium pentoxide (orthorhombic), high hydrophilicity and formation of crystalline calcium phosphate (apatite) under adequate electrolyte composition. Copyright © 2016 Elsevier B.V. All rights reserved.

Surface characterization of anodized zirconium for biomedical applications

NASA Astrophysics Data System (ADS)

Sanchez, A. Gomez; Schreiner, W.; Duffó, G.; Ceré, S.

2011-05-01

Mechanical properties and corrosion resistance of zirconium make this material suitable for biomedical implants. Its good in vivo performance is mainly due to the presence of a protective oxide layer that minimizes corrosion rate, diminishes the amount of metallic ions released to the biological media and facilitates the osseointegration process. Since the implant surface is the region in contact with living tissues, the characteristics of the surface film are of great interest. Surface modification is a route to enhance both biocompatibility and corrosion resistance of permanent implant materials. Anodizing is presented as an interesting process to modify metal surfaces with good reproducibility and independence of the geometry. In this work the surface of zirconium before and after anodizing in 1 mol/L phosphoric acid solution at a fixed potential between 3 and 30 V, was characterized by means of several surface techniques. It was found that during anodization the surface oxide grows with an inhomogeneous coverage on zirconium surface, modifying the topography. The incorporation of P from the electrolyte to the surface oxide during the anodizing process changes the surface chemistry. After 30 days of immersion in Simulated Body Fluid (SBF) solution, Ca-P rich compounds were present on anodized zirconium.

The Deformation Mechanism of Fatigue Behaviour in a N36 Zirconium Alloy

NASA Astrophysics Data System (ADS)

Wang, Yingzhu

2018-05-01

Zirconium alloys are widely used as claddings in nuclear reactor. A N36 zirconium alloy has been deformed into a sheet with highly texture according to the result of electron back scatter diffraction test. Then this N36 zirconium alloy sheet has been cut into small beam samples with 12 x 3 x 3 mm3 in size. In this experiment, a three-point bending test was carried out to investigate the fatigue behaviour of N36 zirconium alloy. Cyclic loadings were applied on the top middle of the beam samples. The region of interest (ROI) is located at the middle bottom of the front face of the beam sample where slip band was observed in deformed beam sample due to strain concentration by using scanning electron microscopy. Twinning also plays an important role to accommodate the plastic deformation of N36 zirconium alloy in fatigue, which displays competition with slip.

In-situ stabilization of radioactive zirconium swarf

DOEpatents

Hess, Clay C.

1999-01-01

The method for treating ignitable cutting swarf in accordance with the present invention involves collecting cutting swarf in a casting mold underwater and injecting a binder mixture comprising vinyl ester styrene into the vessel to fill void volume; and form a mixture comprising swarf and vinyl ester styrene; and curing the mixture. The method is especially useful for stabilizing the ignitable characteristics of radioactive zirconium cutting swarf, and can be used to solidify zirconium swarf, or other ignitable finely divided material, underwater. The process could also be performed out of water with other particulate wastes.

Tailoring the Edge Structure of Molybdenum Disulfide toward Electrocatalytic Reduction of Carbon Dioxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abbasi, Pedram; Asadi, Mohammad; Liu, Cong

2017-01-24

Electrocatalytic conversion of carbon dioxide (CO2) into energy-rich fuels is considered to be the most efficient approach to achieve a carbon neutral cycle. Transition-metal dichalcogenides (TMDCs) have recently shown a very promising catalytic performance for CO2 reduction reaction in an ionic liquid electrolyte. Here, we report that the catalytic performance of molybdenum disulfide (MoS2), a member of TMDCs, can be significantly improved by using an appropriate dopant. Our electrochemical results indicate that 5% niobium (Nb)-doped vertically aligned MoS2 in ionic liquid exhibits 1 order of magnitude higher CO formation turnover frequency (TOF) than pristine MoS2 at an overpotential range ofmore » 50-150 mV. The TOF of this catalyst is also 2 orders of magnitude higher than that of Ag nanoparticles over the entire range of studied overpotentials (100-650 mV). Moreover, the in situ differential electrochemical mass spectrometry experiment shows the onset overpotential of 31 mV for this catalyst, which is the lowest onset potential for CO2 reduction reaction reported so far. Our density functional theory calculations reveal that low concentrations of Nb near the Mo edge atoms can enhance the TOF of CO formation by modifying the binding energies of intermediates to MoS2 edge atoms.« less

Iron-niobium-aluminum alloy having high-temperature corrosion resistance

DOEpatents

Hsu, Huey S.

1988-04-14

An alloy for use in high temperature sulfur and oxygen containing environments, having aluminum for oxygen resistance, niobium for sulfur resistance and the balance iron, is discussed. 4 figs., 2 tabs.

Chemical Vapor Synthesis of Niobium Aluminides

DTIC Science & Technology

1992-01-01

69 4.2.2 Deposition on Singly Supported Niobium Substrates ............ . . . ..... 72 4.3 DEPOSITION OF NbxSiy FROM H2, NbC15 , AND SICl4 ...direct CVD of NbxSiy from the hydrogen reduction of SiCl4 and NbCl5 is described by the overall reaction: xNbCl5 + ySiCl4 + (5x + 4y)/2 H2 - NbxSiy

Hopping conduction in zirconium oxynitrides thin film deposited by reactive magnetron sputtering

NASA Astrophysics Data System (ADS)

Guo, Jie; Zhan, Guanghui; Liu, Jingquan; Yang, Bin; Xu, Bin; Feng, Jie; Chen, Xiang; Yang, Chunsheng

2015-10-01

Zirconium oxynitrides thin film thermometers were demonstrated to be useful temperature sensors. However, the basic conduction mechanism of zirconium oxynitrides films has been a long-standing issue, which hinders the prediction and optimization of their ultimate performance. In this letter, zirconium oxynitrides films were grown on sapphire substrates by magnetron sputtering and their electric transport mechanism has been systemically investigated. It was found that in high temperatures region (>150 K) the electrical conductivity was dominated by thermal activation for all samples. In the low temperatures range, while Mott variable hopping conduction (VRH) was dominated the transport for films with relatively low resistance, a crossover from Mott VRH conduction to Efros-Shklovskii (ES) VRH was observed for films with relatively high resistance. This low temperature crossover from Mott to ES VRH indicates the presence of a Coulomb gap (~7 meV). These results demonstrate the competing and tunable conduction mechanism in zirconium oxynitrides thin films, which would be helpful for optimizing the performance of zirconium oxynitrides thermometer.

Isomerization of Cyclooctadiene to Cyclooctyne with a Zinc/Zirconium Heterobimetallic Complex

PubMed Central

Butler, Michael J.; White, Andrew J. P.

2016-01-01

Abstract Reaction of a zinc/zirconium heterobimetallic complex with 1,5‐cyclooctadiene (1,5‐COD) results in slow isomerization to 1,3‐cyclooctadiene (1,3‐COD), along with the formation of a new complex that includes a cyclooctyne ligand bridging two metal centers. While analogous magnesium/zirconium and aluminum/zirconium heterobimetallic complexes are competent for the catalytic isomerization of 1,5‐COD to 1,3‐COD, only in the case of the zinc species is the cyclooctyne adduct observed. PMID:27071992

Lithium aluminate/zirconium material useful in the production of tritium

DOEpatents

Cawley, W.E.; Trapp, T.J.

A composition is described useful in the production of tritium in a nuclear reactor. Lithium aluminate particles are dispersed in a matrix of zirconium. Tritium produced by the reactor of neutrons with the lithium are absorbed by the zirconium, thereby decreasing gas pressure within capsules carrying the material.

Lithium aluminate/zirconium material useful in the production of tritium

DOEpatents

Cawley, W.E.; Trapp, T.J.

1984-10-09

A composition is described useful in the production of tritium in a nuclear reactor. Lithium aluminate particles are dispersed in a matrix of zirconium. Tritium produced by the reactor of neutrons with the lithium are absorbed by the zirconium, thereby decreasing gas pressure within capsules carrying the material.

Lithium aluminate/zirconium material useful in the production of tritium

DOEpatents

Cawley, William E.; Trapp, Turner J.

1984-10-09

A composition is described useful in the production of tritium in a nuclear eactor. Lithium aluminate particles are dispersed in a matrix of zirconium. Tritium produced by the reactor of neutrons with the lithium are absorbed by the zirconium, thereby decreasing gas pressure within capsules carrying the material.

Anticorrosive Behavior and Porosity of Tricationic Phosphate and Zirconium Conversion Coating on Galvanized Steel

NASA Astrophysics Data System (ADS)

Velasquez, Camilo S.; Pimenta, Egnalda P. S.; Lins, Vanessa F. C.

2018-05-01

This work evaluates the corrosion resistance of galvanized steel treated with tricationic phosphate and zirconium conversion coating after painting, by using electrochemical techniques, accelerated and field corrosion tests. A non-uniform and heterogeneous distribution of zirconium on the steel surface was observed due to preferential nucleation of the zirconium on the aluminum-rich sites on the surface of galvanized steel. The long-term anti-corrosion performance in a saline solution was better for the phosphate coating up to 120 days. The coating capacitance registered a higher increase for the zirconium coatings than the phosphate coatings up to 120 days of immersion. This result agrees with the higher porosity of zirconium coating in relation to the phosphate coating. After 3840 h of accelerated corrosion test, and after 1 year of accelerated field test, zirconium-treated samples showed an average scribe delamination length higher than the phosphate-treated samples.

Anticorrosive Behavior and Porosity of Tricationic Phosphate and Zirconium Conversion Coating on Galvanized Steel

NASA Astrophysics Data System (ADS)

Velasquez, Camilo S.; Pimenta, Egnalda P. S.; Lins, Vanessa F. C.

2018-04-01

This work evaluates the corrosion resistance of galvanized steel treated with tricationic phosphate and zirconium conversion coating after painting, by using electrochemical techniques, accelerated and field corrosion tests. A non-uniform and heterogeneous distribution of zirconium on the steel surface was observed due to preferential nucleation of the zirconium on the aluminum-rich sites on the surface of galvanized steel. The long-term anti-corrosion performance in a saline solution was better for the phosphate coating up to 120 days. The coating capacitance registered a higher increase for the zirconium coatings than the phosphate coatings up to 120 days of immersion. This result agrees with the higher porosity of zirconium coating in relation to the phosphate coating. After 3840 h of accelerated corrosion test, and after 1 year of accelerated field test, zirconium-treated samples showed an average scribe delamination length higher than the phosphate-treated samples.

Effect of low temperature baking on niobium cavities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peter Kneisel; Ganapati Myneni; William Lanford

A low temperature (100 C-150 C) ''in situ'' baking under ultra-high vacuum has been successfully applied as final preparation of niobium RF cavities by several laboratories over the last few years. The benefits reported consist mainly of an improvement of the cavity quality factor and a recovery from the so-called ''Q-drop'' without field emission at high field. A series of experiments with a CEBAF single cell cavity have been carried out at Jefferson Lab to carefully investigate the effect of baking at progressively higher temperatures for a fixed time on all the relevant material parameters. Measurements of the cavity qualitymore » factor in the temperature range 1.37K-280K and resonant frequency shift between 6K-9.3K provide information about the surface resistance, energy gap, penetration depth and mean free path. The experimental data have been analyzed with the complete BCS theory of superconductivity using a modified version of the computer code originally written by J. Halbritter [1] . Small niobium samples inserted in the cavity during its surface preparation were analyzed with respect to their hydrogen content with a Nuclear Reaction Analysis (NRA). The single cell cavity has been tested at three different temperatures before and after baking to gain some insight on thermal conductivity and Kapitza resistance and the data are compared with different models. This paper describes the results from these experiments and comments on the existing models to explain the effect of baking on the performance of niobium RF cavities.« less

A molybdenum disulfide/carbon nanotube heterogeneous complementary inverter.

PubMed

Huang, Jun; Somu, Sivasubramanian; Busnaina, Ahmed

2012-08-24

We report a simple, bottom-up/top-down approach for integrating drastically different nanoscale building blocks to form a heterogeneous complementary inverter circuit based on layered molybdenum disulfide and carbon nanotube (CNT) bundles. The fabricated CNT/MoS(2) inverter is composed of n-type molybdenum disulfide (MOS(2)) and p-type CNT transistors, with a high voltage gain of 1.3. The CNT channels are fabricated using directed assembly while the layered molybdenum disulfide channels are fabricated by mechanical exfoliation. This bottom-up fabrication approach for integrating various nanoscale elements with unique characteristics provides an alternative cost-effective methodology to complementary metal-oxide-semiconductors, laying the foundation for the realization of high performance logic circuits.

METHOD FOR FORMING A COATING OF MOLYBDENUM CARBIDE ON A CARBON BODY

DOEpatents

Simnad, M.T.

1962-04-01

A method is described for coating a carbon bodywith molybdenum carbide in such a manner that the carbon body is rendered less permeable to the flow of gases and has increased resistance to corrosion and erosion. The method includes coating a carbon body with molybdenum trioxide by contacting it at a temperature below the condensation temperature with molybdenum trioxide vapors and thereafter carburizing the molybdenum trioxide in situ in an inert atmosphere on the carhon body. (AEC)

Isomerization of Cyclooctadiene to Cyclooctyne with a Zinc/Zirconium Heterobimetallic Complex.

PubMed

Butler, Michael J; White, Andrew J P; Crimmin, Mark R

2016-06-06

Reaction of a zinc/zirconium heterobimetallic complex with 1,5-cyclooctadiene (1,5-COD) results in slow isomerization to 1,3-cyclooctadiene (1,3-COD), along with the formation of a new complex that includes a cyclooctyne ligand bridging two metal centers. While analogous magnesium/zirconium and aluminum/zirconium heterobimetallic complexes are competent for the catalytic isomerization of 1,5-COD to 1,3-COD, only in the case of the zinc species is the cyclooctyne adduct observed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

PHYSICAL PROPERTIES OF ZIRCONIUM NITRIDE IN THE HOMOGENEITY REGION (in Ukrainian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samsonov, G.V.; Verkhoglyadova, T.S.

1962-01-01

The x-ray method was used to determine the homogeneity region of zirconium nitride as 40 to 50 at.% (9.5 to 13.3% by weight) of nitrogen. It is also shown that part of the ionic bond in the zirconium nitride lattice increases with a decrease in the nitrogen content in this region, this increase being higher than in the homogeneity region of titunium nitride due to the smaller degree of unfilling of the electron d-shell of the zirconium atom in comparison with that of the titanium atom. (auth)

Distribution of Stress in Deformation Zone of Niobium Microalloyed Steel

NASA Astrophysics Data System (ADS)

Jandrlić, Ivan; Rešković, Stoja; Brlić, Tin

2018-03-01

Microalloyed steels today represent a significant part of total world production and processing of steel. Although widely used, there are scarce data on the stress distribution in the deformation zone of these steels. Research was carried out on two steel grades, both low-carbon structural steels with the same basic chemical composition, with one of them additionally microalloyed with niobium. Differences in the stress distribution in the deformation zone between two tested steels were continuously observed and measured using the methods of digital image correlation and thermography. It has been found out that niobium microalloyed steel has significantly more complex material flow and stress distribution in the deformation zone when compared to the plain low carbon steel.

Distribution of Stress in Deformation Zone of Niobium Microalloyed Steel

NASA Astrophysics Data System (ADS)

Jandrlić, Ivan; Rešković, Stoja; Brlić, Tin

2018-07-01

Microalloyed steels today represent a significant part of total world production and processing of steel. Although widely used, there are scarce data on the stress distribution in the deformation zone of these steels. Research was carried out on two steel grades, both low-carbon structural steels with the same basic chemical composition, with one of them additionally microalloyed with niobium. Differences in the stress distribution in the deformation zone between two tested steels were continuously observed and measured using the methods of digital image correlation and thermography. It has been found out that niobium microalloyed steel has significantly more complex material flow and stress distribution in the deformation zone when compared to the plain low carbon steel.

Dual-step synthesis of 3-dimensional niobium oxide - Zinc oxide

NASA Astrophysics Data System (ADS)

Rani, Rozina Abdul; Zoolfakar, Ahmad Sabirin; Rusop, M.

2018-05-01

A facile fabrication process for constructing 3-dimensional (3D) structure of Niobium oxide - Zinc oxide (Nb2O5-ZnO) consisting of branched ZnO microrods on top of nanoporous Nb2O5 films was developed based on dual-step synthesis approach. The preliminary procedure was anodization of sputtered niobium metal on Fluorine doped Tin Oxide (FTO) to produce nanoporous Nb2O5, and continued with the growth of branched microrods of ZnO by hydrothermal process. This approach offers insight knowledge on the development of novel 3D metal oxide films via dual-step synthesis process, which might potentially use for multi-functional applications ranging from sensing to photoconversion.

Nickel-Catalyzed Molybdenum-Promoted Carbonylative Synthesis of Benzophenones.

PubMed

Peng, Jin-Bao; Wu, Fu-Peng; Li, Da; Qi, Xinxin; Ying, Jun; Wu, Xiao-Feng

2018-06-01

A nickel-catalyzed molybdenum-promoted carbonylative coupling reaction for the synthesis of benzophenones from aryl iodides has been developed. Various substituted diaryl ketones were synthesized in moderate to excellent yields under CO-gas-free conditions. A synergetic effect of both nickel and molybdenum has been observed, which is also responsible for the success of this transformation.

In-situ stabilization of radioactive zirconium swarf

DOEpatents

Hess, C.C.

1999-08-31

The method for treating ignitable cutting swarf in accordance with the present invention involves collecting cutting swarf in a casting mold underwater and injecting a binder mixture comprising vinyl ester styrene into the vessel to fill void volume; and form a mixture comprising swarf and vinyl ester styrene; and curing the mixture. The method is especially useful for stabilizing the ignitable characteristics of radioactive zirconium cutting swarf, and can be used to solidify zirconium swarf, or other ignitable finely divided material, underwater. The process could also be performed out of water with other particulate wastes. 6 figs.

Effect of hydrogenation conditions on the microstructure and mechanical properties of zirconium hydride

NASA Astrophysics Data System (ADS)

Muta, Hiroaki; Nishikane, Ryoji; Ando, Yusuke; Matsunaga, Junji; Sakamoto, Kan; Harjo, Stefanus; Kawasaki, Takuro; Ohishi, Yuji; Kurosaki, Ken; Yamanaka, Shinsuke

2018-03-01

Precipitation of brittle zirconium hydrides deteriorate the fracture toughness of the fuel cladding tubes of light water reactor. Although the hydride embrittlement has been studied extensively, little is known about physical properties of the hydride due to the experimental difficulties. In the present study, to elucidate relationship between mechanical properties and microstructure, two δ-phase zirconium hydrides and one ε-phase zirconium hydride were carefully fabricated considering volume changes at the metal-to-hydride transformation. The δ-hydride that was fabricated from α-zirconium exhibits numerous inner cracks due to the large volume change. Analyses of the neutron diffraction pattern and electron backscatter diffraction (EBSD) data show that the sample displays significant stacking faults in the {111} plane and in the pseudo-layered microstructure. On the other hand, the δ-hydride sample fabricated from β-zirconium at a higher temperature displays equiaxed grains and no cracks. The strong crystal orientation dependence of mechanical properties were confirmed by indentation test and EBSD observation. The δ-hydride hydrogenated from α-zirconium displays a lower Young's modulus than that prepared from β-zirconium. The difference is attributed to stacking faults within the {111} plane, for which the Young's modulus exhibits the highest value in the perpendicular direction. The strong influence of the crystal orientation and dislocation density on the mechanical properties should be considered when evaluating hydride precipitates in nuclear fuel cladding.

FY16 Status Report for the Uranium-Molybdenum Fuel Concept

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bennett, Wendy D.; Doherty, Ann L.; Henager, Charles H.

2016-09-22

The Fuel Cycle Research and Development program of the Office of Nuclear Energy has implemented a program to develop a Uranium-Molybdenum metal fuel for light water reactors. Uranium-Molybdenum fuel has the potential to provide superior performance based on its thermo-physical properties. With sufficient development, it may be able to provide the Light Water Reactor industry with a melt-resistant, accident-tolerant fuel with improved safety response. The Pacific Northwest National Laboratory has been tasked with extrusion development and performing ex-reactor corrosion testing to characterize the performance of Uranium-Molybdenum fuel in both these areas. This report documents the results of the fiscal yearmore » 2016 effort to develop the Uranium-Molybdenum metal fuel concept for light water reactors.« less

Cost Estimate for Molybdenum and Tantalum Refractory Metal Alloy Flow Circuit Concepts

NASA Technical Reports Server (NTRS)

Hickman, Robert R.; Martin, James J.; Schmidt, George R.; Godfroy, Thomas J.; Bryhan, A.J.

2010-01-01

The Early Flight Fission-Test Facilities (EFF-TF) team at NASA Marshall Space Flight Center (MSFC) has been tasked by the Naval Reactors Prime Contract Team (NRPCT) to provide a cost and delivery rough order of magnitude estimate for a refractory metal-based lithium (Li) flow circuit. The design is based on the stainless steel Li flow circuit that is currently being assembled for an NRPCT task underway at the EFF-TF. While geometrically the flow circuit is not representative of a final flight prototype, knowledge has been gained to quantify (time and cost) the materials, manufacturing, fabrication, assembly, and operations to produce a testable configuration. This Technical Memorandum (TM) also identifies the following key issues that need to be addressed by the fabrication process: Alloy selection and forming, cost and availability, welding, bending, machining, assembly, and instrumentation. Several candidate materials were identified by NRPCT including molybdenum (Mo) alloy (Mo-47.5 %Re), tantalum (Ta) alloys (T-111, ASTAR-811C), and niobium (Nb) alloy (Nb-1 %Zr). This TM is focused only on the Mo and Ta alloys, since they are of higher concern to the ongoing effort. The initial estimate to complete a Mo-47%Re system ready for testing is =$9,000k over a period of 30 mo. The initial estimate to complete a T-111 or ASTAR-811C system ready for testing is =$12,000k over a period of 36 mo.

PROCESS OF PREPARING ZIRCONIUM OXYCHLORIDE

DOEpatents

Wilhelm, H.A.; Andrews, M.L.

1960-06-28

A process is given for preparing zirconyl chloride by mixing solid zirconyl chloride octahydrate and solid zirconium tetrachloride at room temperature whereby both chlorides are converted to zirconyl chloride trinydrate and hydrogen chloride is formed and volatilized by the reaction heat.

Effect of niobium content on the microstructure and thermal properties of fluorapatite glass-ceramics.

PubMed

Denry, I L; Holloway, J A; Nakkula, R J; Walters, J D

2005-10-01

Niobium oxide has been shown to improve biocompatibility and promote bioactivity. The purpose of this study was to evaluate the effect of niobium oxide additions on the microstructure and thermal properties of fluorapatite glass-ceramics for biomedical applications. Four glass-ceramic compositions with increasing amounts of niobium oxide from 0 to 5 wt % were prepared. The glass compositions were melted at 1,525 degrees C for 3 h, quenched, ground, melted again at 1,525 degrees C for 3 h and furnace cooled. The coefficient of thermal expansion was measured by dilatometry. The crystallization behavior was evaluated by differential thermal analysis. The nature of the crystalline phases was investigated by X-ray diffraction. The microstructure was studied by SEM. In addition, the cytotoxicity of the ceramics was evaluated according to the ASTM standard F895--84. The results from X-ray diffraction analyses showed that fluorapatite was the major crystalline phase in all glass-ceramics. Differential thermal analyses revealed that fluorapatite crystallization occurred between 800 and 934 degrees C depending on the composition. The coefficient of thermal expansion varied from 7.6 to 9.4 x 10(-6)/ degrees C. The microstructure after heat treatment at 975 degrees C for 30 min consisted of submicroscopic fluorapatite crystals (200--300 nm) for all niobium-containing glass-ceramics, whereas the niobium-free glass-ceramic contained needle-shaped fluorapatite crystals, 2 microm in length. None of the glass-ceramics tested exhibited any cytotoxic activity as tested by ASTM standard F895--84. (c) 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2005.

Examination of total cross section resonance structure of niobium and silicon in neutron transmission experiments

NASA Astrophysics Data System (ADS)

Andrianova, Olga; Lomakov, Gleb; Manturov, Gennady

2017-09-01

The neutron transmission experiments are one of the main sources of information about the neutron cross section resonance structure and effect in the self-shielding. Such kind of data for niobium and silicon nuclides in energy range 7 keV to 3 MeV can be obtained from low-resolution transmission measurements performed earlier in Russia (with samples of 0.027 to 0.871 atom/barn for niobium and 0.076 to 1.803 atom/barn for silicon). A significant calculation-to-experiment discrepancy in energy range 100 to 600 keV and 300 to 800 keV for niobium and silicon, respectively, obtained using the evaluated nuclear data library ROSFOND, were found. The EVPAR code was used for estimation the average resonance parameters in energy range 7 to 600 keV for niobium. For silicon a stochastic optimization method was used to modify the resolved resonance parameters in energy range 300 to 800 keV. The improved ROSFOND evaluated nuclear data files were tested in calculation of ICSBEP integral benchmark experiments.

TERNARY ALLOY-CONTAINING PLUTONIUM

DOEpatents

Waber, J.T.

1960-02-23

Ternary alloys of uranium and plutonium containing as the third element either molybdenum or zirconium are reported. Such alloys are particularly useful as reactor fuels in fast breeder reactors. The alloy contains from 2 to 25 at.% of molybdenum or zirconium, the balance being a combination of uranium and plutonium in the ratio of from 1 to 9 atoms of uranlum for each atom of plutonium. These alloys are prepared by melting the constituent elements, treating them at an elevated temperature for homogenization, and cooling them to room temperature, the rate of cooling varying with the oomposition and the desired phase structure. The preferred embodiment contains 12 to 25 at.% of molybdenum and is treated by quenching to obtain a body centered cubic crystal structure. The most important advantage of these alloys over prior binary alloys of both plutonium and uranium is the lack of cracking during casting and their ready machinability.

Alloy hardening and softening in binary molybdenum alloys as related to electron concentration

NASA Technical Reports Server (NTRS)

Stephens, J. R.; Witzke, W. R.

1972-01-01

An investigation was conducted to determine the effects of alloy additions of hafnium, tantalum, tungsten, rhenium, osmium, iridium, and platinum on hardness of molybdenum. Special emphasis was placed on alloy softening in these binary molybdenum alloys. Results showed that alloy softening was produced by those elements having an excess of s+d electrons compared to molybdenum, while those elements having an equal number or fewer s+d electrons that molybdenum failed to produce alloy softening. Alloy softening and alloy hardening can be correlated with the difference in number of s+d electrons of the solute element and molybdenum.

Intercalation chemistry of zirconium 4-sulfophenylphosphonate

NASA Astrophysics Data System (ADS)

Svoboda, Jan; Zima, Vítězslav; Melánová, Klára; Beneš, Ludvík; Trchová, Miroslava

2013-12-01

Zirconium 4-sulfophenylphosphonate is a layered material which can be employed as a host for the intercalation reactions with basic molecules. A wide range of organic compounds were chosen to represent intercalation ability of zirconium 4-sulfophenylphosphonate. These were a series of alkylamines from methylamine to dodecylamine, 1,4-phenylenediamine, p-toluidine, 1,8-diaminonaphthalene, 1-aminopyrene, imidazole, pyridine, 4,4‧-bipyridine, poly(ethylene imine), and a series of amino acids from glycine to 6-aminocaproic acid. The prepared compounds were characterized by powder X-ray diffraction, thermogravimetry analysis and IR spectroscopy and probable arrangement of the guest molecules in the interlayer space of the host is proposed based on the interlayer distance of the prepared intercalates and amount of the intercalated guest molecules.

Modification of molybdenum disulfide in methanol solvent for hydrogen evolution reaction

NASA Astrophysics Data System (ADS)

Niyitanga, Theophile; Jeong, Hae Kyung

2018-05-01

Molybdenum disulfide is a promising catalyst to replace the expensive platinum as an electrocatalyst but needs to be modified to present excellent electrocatalytic properties. Herein, we successfully modify molybdenum disulfide in methanol solvent for hydrogen evolution reaction by using a simple hydrothermal method. Overpotential reduced to -0.6 V from -1.5 V, and energy band gap decreased from 1.73 eV to 1.58 eV after the modification. The modified molybdenum disulfide also demonstrated lower resistance (42 Ω) at high frequency (1000 kHz) compared with that (240 Ω) of the precursor, showing that conductivity of the modified molybdenum disulfide has improved.

Recovery of Tungsten and Molybdenum from Low-Grade Scheelite

NASA Astrophysics Data System (ADS)

Li, Yongli; Yang, Jinhong; Zhao, Zhongwei

2017-10-01

With most high-quality tungsten ores being exhausted, the enhancement of low-grade scheelite concentrates processing has attracted a great deal of attention. The objective of this study is to develop a method to maximize the recovery tungsten and molybdenum from a low-grade scheelite via a new acid leaching process followed by solvent extraction. Under optimal conditions (350 g/L H2SO4, 95°C, and 2 h), approximately 99.8% of tungsten and 98% of molybdenum were leached out. In the subsequent solvent extraction process, more than 99% of the tungsten and molybdenum were extracted with a co-extraction system (50% TBP, 30% HDEHP, and 10% 2-octanol in kerosene) using a three-stage cross-flow extraction. The raffinate can be recycled for the next leaching process after replenishing the H2SO4 to the initial value (approximately 350 g/L). Based on these results, a conceptual flowsheet is presented to recover tungsten and molybdenum from the low-grade scheelite.

Thermodynamic Analysis and Growth of Zirconium Carbide by Chemical Vapor Deposition

NASA Astrophysics Data System (ADS)

Wei, Sun; Hua, Hao Zheng; Xiang, Xiong

Equilibrium calculations were used to optimize conditions for the chemical vapor deposition of zirconium carbide from zirconium halide + CxHy+H2+Ar system. The results show the CVD-ZrC phase diagram is divided into ZrC+C, ZrC and ZrC+Zr zones by C, Zr generating lines. For the same mole of ZrCl4 reactant, it needs higher concentration of CH4 to generate single ZrC phase than that of C3H6. Using these calculations as a guide, single-phase cubic zirconium carbide coatings were deposited onto graphite substrate.

Evaluation of a Zirconium Recycle Scrubber System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spencer, Barry B.; Bruffey, Stephanie H.

2017-04-01

A hot-cell demonstration of the zirconium recycle process is planned as part of the Materials Recovery and Waste Forms Development (MRWFD) campaign. The process treats Zircaloy® cladding recovered from used nuclear fuel with chlorine gas to recover the zirconium as volatile ZrCl4. This releases radioactive tritium trapped in the alloy, converting it to volatile tritium chloride (TCl). To meet regulatory requirements governing radioactive emissions from nuclear fuel treatment operations, the capture and retention of a portion of this TCl may be required prior to discharge of the off-gas stream to the environment. In addition to demonstrating tritium removal from amore » synthetic zirconium recycle off-gas stream, the recovery and quantification of tritium may refine estimates of the amount of tritium present in the Zircaloy cladding of used nuclear fuel. To support these objectives, a bubbler-type scrubber was fabricated to remove the TCl from the zirconium recycle off-gas stream. The scrubber was fabricated from glass and polymer components that are resistant to chlorine and hydrochloric acid solutions. Because of concerns that the scrubber efficiency is not quantitative, tests were performed using DCl as a stand-in to experimentally measure the scrubbing efficiency of this unit. Scrubbing efficiency was ~108% ± 3% with water as the scrubber solution. Variations were noted when 1 M NaOH scrub solution was used, values ranged from 64% to 130%. The reason for the variations is not known. It is recommended that the equipment be operated with water as the scrubbing solution. Scrubbing efficiency is estimated at 100%.« less

78 FR 42584 - Bureau of International Security and Nonproliferation: Report to Congress Pursuant to Section...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-16

...-finished metals such as aluminum and steel, coal, and software for integrating industrial processes. We...; boron; cobalt; copper; copper infiltrated tungsten; copper- beryllium; graphite; hastelloy; inconel; magnesium; molybdenum; nickel; niobium; silver infiltrated tungsten; steels (including, but not limited to...

Magnetic Property in Large Array Niobium Antidot Thin Films

NASA Astrophysics Data System (ADS)

Tinghui, Chen; Hsiang-Hsi, Kung; Wei-Li, Lee; Institute of Physics, Academia Sinica, Taipei, Taiwan Team

2014-03-01

In a superconducting ring, the total flux inside the ring is required to be an integer number of the flux quanta. Therefore, a supercurrent current can appear within the ring in order to satisfy this quantization rule, which gives rise to certain magnetic response. By using a special monolayer polymer/nanosphere hybrid we developed previously, we fabricated a series of superconducting niobium antidot thin films with different antidot diameters. The antidots form well-ordered triangular lattice with a lattice spacing about 200 nm and extend over an area larger than 1 cm2, which enables magnetic detections simply by a SQUID magnetometer. We observed magnetization oscillation with external magnetic field due to the supercurrent screening effect, where different features for large and small antidot thin films were found. Detailed size and temperature dependencies of the magnetization in niobium antidot nanostructures will be presented.

Extractive separation of uranium and zirconium sulfates by amines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schroetterova, D.; Nekovar, P.; Mrnka, M.

1992-04-01

This paper describes an amine extraction process for zirconium and uranium separation. The behaviour of an extraction system containing uranium (VI) sulfate, zirconium (IV) sulfate, 0.2 and 0.5 M sulfuric acid (as the original aqueous phase), tertiary amine tri-n-lauryl- amine or primary amine Primene JMT in benzene (as the original organic phase) is discussed on the basis of equilibrium data. The measured dependences show that the degree of extraction of zirconium at the sulfuric acid concentration of 0.5 M and above is only slightly affected by a presence of uranium in solution. From this surprising behaviour it follows that zirconiummore » may be employed for the displacement of uranium from the organic phase. This effect is more pronounced with the primary amine Primene JMT than with TLA. 29 refs., 4 figs., 1 tab.« less

Parallel Critical Field in Thin Niobium Films: Comparison to Theory

NASA Astrophysics Data System (ADS)

Broussard, P. R.

2017-10-01

For the first time, a comparison to the predicted behavior for parallel critical field is carried out for the model of Kogan and the model of Hara and Nagai. In this study, thin niobium films in the moderately dirty regime were considered. Experimental values of the -C2 term are seen to be lower than those from the model of Hara and Nagai. A possible reason for this could be not including the non-spherical Fermi surface of niobium into the model. There is clearly disagreement with the model of Kogan as the films get cleaner and thinner, and two films which should be below his critical thickness still show positive values of -C2, in disagreement with his theory.

Environmental Benign Process for Production of Molybdenum Metal from Sulphide Based Minerals

NASA Astrophysics Data System (ADS)

Rajput, Priyanka; Janakiram, Vangada; Jayasankar, Kalidoss; Angadi, Shivakumar; Bhoi, Bhagyadhar; Mukherjee, Partha Sarathi

2017-10-01

Molybdenum is a strategic and high temperature refractory metal which is not found in nature in free state, it is predominantly found in earth's crust in the form of MoO3/MoS2. The main disadvantage of the industrial treatment of Mo concentrate is that the process contains many stages and requires very high temperature. Almost in every step many gaseous, liquid, solid chemical substances are formed which require further treatment. To overcome the above drawback, a new alternative one step novel process is developed for the treatment of sulphide and trioxide molybdenum concentrates. This paper presents the results of the investigations on molybdenite dissociation (MoS2) using microwave assisted plasma unit as well as transferred arc thermal plasma torch. It is a single step process for the preparation of pure molybdenum metal from MoS2 by hydrogen reduction in thermal plasma. Process variable such as H2 gas, Ar gas, input current, voltage and time have been examined to prepare molybdenum metal. Molybdenum recovery of the order of 95% was achieved. The XRD results confirm the phases of molybdenum metal and the chemical analysis of the end product indicate the formation of metallic molybdenum (Mo 98%).

21 CFR 700.16 - Use of aerosol cosmetic products containing zirconium.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 7 2013-04-01 2013-04-01 false Use of aerosol cosmetic products containing... SERVICES (CONTINUED) COSMETICS GENERAL Requirements for Specific Cosmetic Products § 700.16 Use of aerosol cosmetic products containing zirconium. (a) Zirconium-containing complexes have been used as an ingredient...

21 CFR 700.16 - Use of aerosol cosmetic products containing zirconium.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 7 2012-04-01 2012-04-01 false Use of aerosol cosmetic products containing... SERVICES (CONTINUED) COSMETICS GENERAL Requirements for Specific Cosmetic Products § 700.16 Use of aerosol cosmetic products containing zirconium. (a) Zirconium-containing complexes have been used as an ingredient...

21 CFR 700.16 - Use of aerosol cosmetic products containing zirconium.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 7 2014-04-01 2014-04-01 false Use of aerosol cosmetic products containing... SERVICES (CONTINUED) COSMETICS GENERAL Requirements for Specific Cosmetic Products § 700.16 Use of aerosol cosmetic products containing zirconium. (a) Zirconium-containing complexes have been used as an ingredient...

From Zirconium Nanograins to Zirconia Nanoneedles

PubMed Central

Zalnezhad, E.; Hamouda, A. M. S.; Jaworski, J.; Do Kim, Young

2016-01-01

Combinations of three simple techniques were utilized to gradually form zirconia nanoneedles from zirconium nanograins. First, a physical vapor deposition magnetron sputtering technique was used to deposit pure zirconium nanograins on top of a substrate. Second, an anodic oxidation was applied to fabricate zirconia nanotubular arrays. Finally, heat treatment was used at different annealing temperatures in order to change the structure and morphology from nanotubes to nanowires and subsequently to nanoneedles in the presence of argon gas. The size of the pure zirconium nanograins was estimated to be approximately 200–300 nm. ZrO2 nanotubular arrays with diameters of 70–120 nm were obtained. Both tetragonal and monoclinic ZrO2 were observed after annealing at 450 °C and 650 °C. Only a few tetragonal peaks appeared at 850 °C, while monoclinic ZrO2 was obtained at 900 °C and 950 °C. In assessing the biocompatibility of the ZrO2 surface, the human cell line MDA-MB-231 was found to attach and proliferate well on surfaces annealed at 850 °C and 450 °C; however, the amorphous ZrO2 surface, which was not heat treated, did not permit extensive cell growth, presumably due to remaining fluoride. PMID:27623486

Synthesis and thermal evolution of structure in alkoxide-derived niobium pentoxide gels

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.

1993-01-01

Niobium pentoxide gels in the form of transparent monoliths and powder have been synthesized from the controlled hydrolysis and polycondensation of niobium pentaethoxide under different experimental conditions using various mole ratios of Nb(OC2H5)5:H2O:C2H5OH:HCl. Alcohol acted as the mutual solvent and HCl as the deflocculating agent. In the absence of HCl, precipitation of colloidal particles was encountered on the addition of any water to the alkoxide. The gels were subjected to various thermal treatments and characterized by differential thermal analysis, thermogravimetric analysis, x-ray diffraction, and infrared spectroscopy. After drying at 400 C, the gels were amorphous to x-rays. The amorphous powder crystallized into the low-temperature orthorhombic form of Nb2O5 at approximately 500 C, which transformed irreversibly into the high-temperature monoclinic alpha-Nb2O5 between 900 to 1000 C. The kinetics of crystallization of the amorphous niobium pentoxide have been investigated by non-isothermal differential scanning calorimetry. The crystallization activation energy was determined to be 399 kJ/mol.

Reduction of molybdate to molybdenum blue by Klebsiella sp. strain hkeem.

PubMed

Lim, H K; Syed, M A; Shukor, M Y

2012-06-01

A novel molybdate-reducing bacterium, tentatively identified as Klebsiella sp. strain hkeem and based on partial 16s rDNA gene sequencing and phylogenetic analysis, has been isolated. Strain hkeem produced 3 times more molybdenum blue than Serratia sp. strain Dr.Y8; the most potent Mo-reducing bacterium isolated to date. Molybdate was optimally reduced to molybdenum blue using 4.5 mM phosphate, 80 mM molybdate and using 1% (w/v) fructose as a carbon source. Molybdate reduction was optimum at 30 °C and at pH 7.3. The molybdenum blue produced from cellular reduction exhibited absorption spectrum with a maximum peak at 865 nm and a shoulder at 700 nm. Inhibitors of electron transport system such as antimycin A, rotenone, sodium azide, and potassium cyanide did not inhibit the molybdenum-reducing enzyme. Mercury, silver, and copper at 1 ppm inhibited molybdenum blue formation in whole cells of strain hkeem. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Deuterium retention and release from molybdenum exposed to a Penning discharge

NASA Astrophysics Data System (ADS)

Causey, R. A.; Kunz, C. L.; Cowgill, D. F.

2005-03-01

Both molybdenum and tungsten are candidate materials for plasma-facing applications in fusion reactors. While tungsten has a higher melting point and a higher threshold for sputtering, it is a brittle material that is difficult to machine into shapes required for fusion applications. For this reason, molybdenum is now receiving serious consideration as an alternative for tungsten. If molybdenum is to be used as a plasma-facing material, the hydrogen retention and recycling characteristics must be known. In this report, we present experimental results on deuterium retention in molybdenum after exposure to a Penning discharge at temperatures from 573 to 773 K. D2+ ions with energies of 1.2 keV were implanted into the 50 mm diameter molybdenum samples at fluxes of 10 20 D/m 2 s. Thermal desorption spectroscopy was used to determine both the amount of retained deuterium and the release kinetics. Low retention values similar to those measured previously for tungsten were observed.

Bioaccessibility of micron-sized powder particles of molybdenum metal, iron metal, molybdenum oxides and ferromolybdenum--Importance of surface oxides.

PubMed

Mörsdorf, Alexander; Odnevall Wallinder, Inger; Hedberg, Yolanda

2015-08-01

The European chemical framework REACH requires that hazards and risks posed by chemicals, including alloys and metals, that are manufactured, imported or used in different products (substances or articles) are identified and proven safe for humans and the environment. Metals and alloys need hence to be investigated on their extent of released metals (bioaccessibility) in biologically relevant environments. Read-across from available studies may be used for similar materials. This study investigates the release of molybdenum and iron from powder particles of molybdenum metal (Mo), a ferromolybdenum alloy (FeMo), an iron metal powder (Fe), MoO2, and MoO3 in different synthetic body fluids of pH ranging from 1.5 to 7.4 and of different composition. Spectroscopic tools and cyclic voltammetry have been employed to characterize surface oxides, microscopy, light scattering and nitrogen absorption for particle characterization, and atomic absorption spectroscopy to quantify released amounts of metals. The release of molybdenum from the Mo powder generally increased with pH and was influenced by the fluid composition. The mixed iron and molybdenum surface oxide of the FeMo powder acted as a barrier both at acidic and weakly alkaline conditions. These findings underline the importance of the surface oxide characteristics for the bioaccessibility of metal alloys. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

40 CFR 421.210 - Applicability: Description of the primary molybdenum and rhenium subcategory.

Code of Federal Regulations, 2013 CFR

2013-07-01

... primary molybdenum and rhenium subcategory. 421.210 Section 421.210 Protection of Environment... POINT SOURCE CATEGORY Primary Molybdenum and Rhenium Subcategory § 421.210 Applicability: Description of the primary molybdenum and rhenium subcategory. The provisions of this subpart are applicable to...

40 CFR 421.210 - Applicability: Description of the primary molybdenum and rhenium subcategory.

Code of Federal Regulations, 2012 CFR

2012-07-01

... primary molybdenum and rhenium subcategory. 421.210 Section 421.210 Protection of Environment... POINT SOURCE CATEGORY Primary Molybdenum and Rhenium Subcategory § 421.210 Applicability: Description of the primary molybdenum and rhenium subcategory. The provisions of this subpart are applicable to...

40 CFR 421.210 - Applicability: Description of the primary molybdenum and rhenium subcategory.

Code of Federal Regulations, 2014 CFR

2014-07-01

... primary molybdenum and rhenium subcategory. 421.210 Section 421.210 Protection of Environment... POINT SOURCE CATEGORY Primary Molybdenum and Rhenium Subcategory § 421.210 Applicability: Description of the primary molybdenum and rhenium subcategory. The provisions of this subpart are applicable to...

40 CFR 421.210 - Applicability: Description of the primary molybdenum and rhenium subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... primary molybdenum and rhenium subcategory. 421.210 Section 421.210 Protection of Environment... POINT SOURCE CATEGORY Primary Molybdenum and Rhenium Subcategory § 421.210 Applicability: Description of the primary molybdenum and rhenium subcategory. The provisions of this subpart are applicable to...

40 CFR 421.210 - Applicability: Description of the primary molybdenum and rhenium subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... primary molybdenum and rhenium subcategory. 421.210 Section 421.210 Protection of Environment... POINT SOURCE CATEGORY Primary Molybdenum and Rhenium Subcategory § 421.210 Applicability: Description of the primary molybdenum and rhenium subcategory. The provisions of this subpart are applicable to...

Electrochemical way of molybdenum extraction from the Bimetallic systems of Mo-W

NASA Astrophysics Data System (ADS)

Kudreeva, L. K.; Nauryzbaev, M. K.; Kurbatov, A. P.; Kamysbaev, D. H.; Adilbekova, A. O.; Mukataeva, Z. S.

2015-12-01

Electrochemical dissolution of molybdenum and tungsten was investigated in water- dimethylsulfoxide (DMSO) media at different concentrations of lithium chloride and magnesium perchlorate. The terms of efficient extraction of molybdenum from bimetallic systems of Mo-W have been determined. The polarization curves of the electrooxidation of molybdenum in the solution of 0.25 M LiCl in the DMSO at the different rates of rotations and the scan rate equal to 50 mV/s were obtained. In the presence of the addition of water at the potential of 0.1-0.75 V the small area of polarizability occurs, then with increasing potentials above 1.5 V there is a sharp increase of the oxidation current. Comparison of the current values of anodic dissolution of molybdenum and tungsten showed that the rate of anodic dissolution of molybdenum significantly exceeds the rate of anodic dissolution of tungsten. In the case of molybdenum, the dissolution process is limited by diffusion, in the case of tungsten - by the passive film formation on the electrode surface.

Translucency and Strength of High-Translucency Monolithic Zirconium-Oxide Materials

DTIC Science & Technology

2016-05-12

APPROV~, Col Drew W. Fallis Dean, Air Force Postgraduate Dental School r UNIFORMED SERVICES UNIVERSITY OF THE HEALTH SCIENCES AIR FORCE...POSTGRADUATE DENTAL SCHOOL 2450 Pepperrell Street Lackland AFB Texas, 78236-5345 http://www.usuhs.mil "The author hereby certifies that the use of any...Translucency Monolithic Zirconium-Oxide Materials Abstract Dental materials manufacturers have developed more translucent monolithic zirconium oxide

Rate limiting mechanisms in lithium-molybdenum disulfide batteries

NASA Astrophysics Data System (ADS)

Laman, F. C.; Stiles, J. A. R.; Brandt, K.; Shank, R. J.

1985-03-01

One limitation of secondary lithium batteries using intercalation cathodes is generally related to relatively low power densities. Significant advances towards overcoming this limitation have been made in cells based on a utilization of lithium-molybdenum disulfide technology. Rate limiting mechanisms in cells of the lithium-molybdenum disulfide system have been studied with the aid of a frequency response analysis. It was found that diffusion-related contributions to cell impedance, and interfacial and resistive contributions to cell impedance, can be readily segregated by virtue of the fact that the diffusion-controlled mechanisms dominate the low frequency end of the impedance spectra, while the other mechanisms dominate the high frequency end. The present investigation is concerned with rate limitations at the high end of the frequency spectrum in lithium-molybdenum disulfide cathodes.

Determination of fluoride in water - A modified zirconium-alizarin method

USGS Publications Warehouse

Lamar, W.L.

1945-01-01

A convenient, rapid colorimetric procedure using the zirconium-alizarin indicator acidified with sulfuric acid for the determination of fluoride in water is described. Since this acid indicator is stable indefinitely, it is more useful than other zirconium-alizarin reagents previously reported. The use of sulfuric acid alone in acidifying the zirconium-alizarin reagent makes possible the maximum suppression of the interference of sulfate. Control of the pH of the samples eliminates errors due to the alkalinity of the samples. The fluoride content of waters containing less than 500 parts per million of sulfate and less than 1000 p.p.m. of chloride may be determined within a limit of 0.1 p.p.m. when a 100-ml. sample is used.

Molybdenum oxide and molybdenum oxide-nitride back contacts for CdTe solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Drayton, Jennifer A., E-mail: drjadrayton@yahoo.com; Geisthardt, Russell M., E-mail: Russell.Geisthardt@gmail.com; Sites, James R., E-mail: james.sites@colostate.edu

2015-07-15

Molybdenum oxide (MoO{sub x}) and molybdenum oxynitride (MoON) thin film back contacts were formed by a unique ion-beam sputtering and ion-beam-assisted deposition process onto CdTe solar cells and compared to back contacts made using carbon–nickel (C/Ni) paint. Glancing-incidence x-ray diffraction and x-ray photoelectron spectroscopy measurements show that partially crystalline MoO{sub x} films are created with a mixture of Mo, MoO{sub 2}, and MoO{sub 3} components. Lower crystallinity content is observed in the MoON films, with an additional component of molybdenum nitride present. Three different film thicknesses of MoO{sub x} and MoON were investigated that were capped in situ in Ni.more » Small area devices were delineated and characterized using current–voltage (J-V), capacitance–frequency, capacitance–voltage, electroluminescence, and light beam-induced current techniques. In addition, J-V data measured as a function of temperature (JVT) were used to estimate back barrier heights for each thickness of MoO{sub x} and MoON and for the C/Ni paint. Characterization prior to stressing indicated the devices were similar in performance. Characterization after stress testing indicated little change to cells with 120 and 180-nm thick MoO{sub x} and MoON films. However, moderate-to-large cell degradation was observed for 60-nm thick MoO{sub x} and MoON films and for C/Ni painted back contacts.« less

Efficient One-Pot Synthesis of Colloidal Zirconium Oxide Nanoparticles for High-Refractive-Index Nanocomposites.

PubMed

Liu, Chao; Hajagos, Tibor Jacob; Chen, Dustin; Chen, Yi; Kishpaugh, David; Pei, Qibing

2016-02-01

Zirconium oxide nanoparticles are promising candidates for optical engineering, photocatalysis, and high-κ dielectrics. However, reported synthetic methods for the colloidal zirconium oxide nanoparticles use unstable alkoxide precursors and have various other drawbacks, limiting their wide application. Here, we report a facile one-pot method for the synthesis of colloidally stable zirconium oxide nanoparticles. Using a simple solution of zirconium trifluoroacetate in oleylamine, highly stable zirconium oxide nanoparticles have been synthesized with high yield, following a proposed amidization-assisted sol-gel mechanism. The nanoparticles can be readily dispersed in nonpolar solvents, forming a long-term stable transparent solution, which can be further used to fabricate high-refractive-index nanocomposites in both monolith and thin-film forms. In addition, the same method has also been extended to the synthesis of titanium oxide nanoparticles, demonstrating its general applicability to all group IVB metal oxide nanoparticles.

Zirconium Phosphate Supported MOF Nanoplatelets.

PubMed

Kan, Yuwei; Clearfield, Abraham

2016-06-06

We report a rare example of the preparation of HKUST-1 metal-organic framework nanoplatelets through a step-by-step seeding procedure. Sodium ion exchanged zirconium phosphate, NaZrP, nanoplatelets were judiciously selected as support for layer-by-layer (LBL) assembly of Cu(II) and benzene-1,3,5-tricarboxylic acid (H3BTC) linkers. The first layer of Cu(II) is attached to the surface of zirconium phosphate through covalent interaction. The successive LBL growth of HKUST-1 film is then realized by soaking the NaZrP nanoplatelets in ethanolic solutions of cupric acetate and H3BTC, respectively. The amount of assembled HKUST-1 can be readily controlled by varying the number of growth cycles, which was characterized by powder X-ray diffraction and gas adsorption analyses. The successful construction of HKUST-1 on NaZrP was also supported by its catalytic performance for the oxidation of cyclohexene.

Calculated mammographic spectra confirmed with attenuation curves for molybdenum, rhodium, and tungsten targets.

PubMed

Blough, M M; Waggener, R G; Payne, W H; Terry, J A

1998-09-01

A model for calculating mammographic spectra independent of measured data and fitting parameters is presented. This model is based on first principles. Spectra were calculated using various target and filter combinations such as molybdenum/molybdenum, molybdenum/rhodium, rhodium/rhodium, and tungsten/aluminum. Once the spectra were calculated, attenuation curves were calculated and compared to measured attenuation curves. The attenuation curves were calculated and measured using aluminum alloy 1100 or high purity aluminum filtration. Percent differences were computed between the measured and calculated attenuation curves resulting in an average of 5.21% difference for tungsten/aluminum, 2.26% for molybdenum/molybdenum, 3.35% for rhodium/rhodium, and 3.18% for molybdenum/rhodium. Calculated spectra were also compared to measured spectra from the Food and Drug Administration [Fewell and Shuping, Handbook of Mammographic X-ray Spectra (U.S. Government Printing Office, Washington, D.C., 1979)] and a comparison will also be presented.

Two-phase chromium-niobium alloys exhibiting improved mechanical properties at high temperatures

DOEpatents

Liu, Chain T.; Takeyama, Masao

1994-01-01

The specification discloses chromium-niobium alloys which exhibit improved mechanical properties at high temperatures in the range of 1250.degree. C. and improved room temperature ductility. The alloys contain a Cr.sub.2 Nb-rich intermetallic phase and a Cr-rich phase with an overall niobium concentration in the range of from about 5 to about 18 at. %. The high temperature strength is substantially greater than that of state of the art nickel-based superalloys for enhanced high temperature service. Further improvements in the properties of the compositions are obtained by alloying with rhenium and aluminum; and additional rare-earth and other elements.

Rare-Earth Ions in Niobium-Based Devices as a Quantum Memory: Magneto-Optical Effects on Room Temperature Electrical Transport

DTIC Science & Technology

2016-09-01

rare-earth neodymium by ion implantation in thin films of niobium and niobium-based heterostructure devices. We model the ion implantation process...the films and devices so they can properly designed and optimized for utility as quantum memory. We find that the magnetic field has a strong effect...thin films of niobium. Simulations are made at low 1013 cm-2 and high 1014 cm-2 dose at 60 keV. At high dose, disorder induced is significantly

Zirconium carbide as an electrocatalyst for the chromous-chromic redox couple

NASA Technical Reports Server (NTRS)

Gahn, R. F.; Reid, M. A.; Yang, C. Y. (Inventor)

1981-01-01

Zirconium carbide is used as a catalyst in a REDOX cell for the oxidation of chromous ions to chromic ions and for the reduction of chromic ions to chromous ions. The zirconium carbide is coated on an inert electronically conductive electrode which is present in the anode fluid of the cell.

New porous titanium–niobium oxide for photocatalytic degradation of bromocresol green dye in aqueous solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chaleshtori, Maryam Zarei, E-mail: mzarei@utep.edu; Hosseini, Mahsa; Edalatpour, Roya

2013-10-15

Graphical abstract: The photocatalytic activity of different porous titanium–niobium oxides was evaluated toward degradation of bromocresol green (BG) under UV light. A better catalytic activity was observed for all samples at lower pH. Catalysts have a stronger ability for degradation of BG in acid media than in alkaline media. - Highlights: • Different highly structured titanium–niobium oxides have been prepared using improved methods of synthesis. • Photo-degradation of bromocresol green dye (BG) with nanostructure titanium–niobium oxide catalysts was carried out under UV light. • The photo-catalytic activity of all catalysts was higher in lower pH. • Titanium–niobium oxide catalysts aremore » considerably stable and reusable. - Abstract: In this study, high surface area semiconductors, non porous and porous titanium–niobium oxides derived from KTiNbO{sub 5} were synthesized, characterized and developed for their utility as photocatalysts for decontamination with sunlight. These materials were then used in the photocatalytic degradation of bromocresol green dye (BG) in aqueous solution using UV light and their catalytic activities were evaluated at various pHs. For all catalysts, the photocatalytic degradation of BG was most efficient in acidic solutions. Results show that the new porous oxides have large porous and high surface areas and high catalytic activity. A topotactic dehydration treatment greatly improves catalyst performance at various pHs. Stability and long term activity of porous materials (topo and non-topo) in photocatalysis reactions was also tested. These results suggest that the new materials can be used to efficiently purify contaminated water.« less

Flexible Molybdenum Electrodes towards Designing Affinity Based Protein Biosensors

PubMed Central

Kamakoti, Vikramshankar; Panneer Selvam, Anjan; Radha Shanmugam, Nandhinee; Muthukumar, Sriram; Prasad, Shalini

2016-01-01

Molybdenum electrode based flexible biosensor on porous polyamide substrates has been fabricated and tested for its functionality as a protein affinity based biosensor. The biosensor performance was evaluated using a key cardiac biomarker; cardiac Troponin-I (cTnI). Molybdenum is a transition metal and demonstrates electrochemical behavior upon interaction with an electrolyte. We have leveraged this property of molybdenum for designing an affinity based biosensor using electrochemical impedance spectroscopy. We have evaluated the feasibility of detection of cTnI in phosphate-buffered saline (PBS) and human serum (HS) by measuring impedance changes over a frequency window from 100 mHz to 1 MHz. Increasing changes to the measured impedance was correlated to the increased dose of cTnI molecules binding to the cTnI antibody functionalized molybdenum surface. We achieved cTnI detection limit of 10 pg/mL in PBS and 1 ng/mL in HS medium. The use of flexible substrates for designing the biosensor demonstrates promise for integration with a large-scale batch manufacturing process. PMID:27438863

Flexible Molybdenum Electrodes towards Designing Affinity Based Protein Biosensors.

PubMed

Kamakoti, Vikramshankar; Panneer Selvam, Anjan; Radha Shanmugam, Nandhinee; Muthukumar, Sriram; Prasad, Shalini

2016-07-18

Molybdenum electrode based flexible biosensor on porous polyamide substrates has been fabricated and tested for its functionality as a protein affinity based biosensor. The biosensor performance was evaluated using a key cardiac biomarker; cardiac Troponin-I (cTnI). Molybdenum is a transition metal and demonstrates electrochemical behavior upon interaction with an electrolyte. We have leveraged this property of molybdenum for designing an affinity based biosensor using electrochemical impedance spectroscopy. We have evaluated the feasibility of detection of cTnI in phosphate-buffered saline (PBS) and human serum (HS) by measuring impedance changes over a frequency window from 100 mHz to 1 MHz. Increasing changes to the measured impedance was correlated to the increased dose of cTnI molecules binding to the cTnI antibody functionalized molybdenum surface. We achieved cTnI detection limit of 10 pg/mL in PBS and 1 ng/mL in HS medium. The use of flexible substrates for designing the biosensor demonstrates promise for integration with a large-scale batch manufacturing process.

Superconductivity in zirconium-rhodium alloys

NASA Technical Reports Server (NTRS)

Zegler, S. T.

1969-01-01

Metallographic studies and transition temperature measurements were made with isothermally annealed and water-quenched zirconium-rhodium alloys. The results clarify both the solid-state phase relations at the Zr-rich end of the Zr-Rh alloy system and the influence upon the superconducting transition temperature of structure and composition.

Microstructure evolution and tensile properties of Zr-2.5wt%Nb pressure tubes processed from billets with different microstructures

NASA Astrophysics Data System (ADS)

Kapoor, K.; Saratchandran, N.; Muralidharan, K.

1999-02-01

Starting with identical ingots, billets having different microstructures were obtained by three different processing methods for fabrication of Zr-2.5wt%Nb pressure tubes. The billets were further processed by hot extrusion and cold Pilger tube reducing to the finished product. Microstructural characterization was done at each stage of processing. The effects of the initial billet microstructure on the intermediate and final microstructure and mechanical property results were determined. It was found that the structure at each stage and the final mechanical properties depend strongly on the initial billet microstructure. The structure at the final stage consists of elongated alpha zirconium grains with a network of metastable beta zirconium phase. Some of this metastable phase transforms into stable beta niobium during thermomechanical processing. Billets with quenched structure resulted in less beta niobium at the final stage. The air cooled billets resulted in a large amount of beta niobium. The tensile properties, especially the percentage elongation, were found to vary for the different methods. Higher percentage elongation was observed for billets having quenched structure. Extrusion and forging did not produce any characteristic differences in the properties. The results were used to select a process flow sheet which yields the desired mechanical properties with suitable microstructure in the final product.

21 CFR 700.16 - Use of aerosol cosmetic products containing zirconium.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 7 2011-04-01 2010-04-01 true Use of aerosol cosmetic products containing zirconium. 700.16 Section 700.16 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... and other organs of experimental animals. When used in aerosol form, some zirconium will reach the...

High-Performance Supercapacitors from Niobium Nanowire Yarns.

PubMed

Mirvakili, Seyed M; Mirvakili, Mehr Negar; Englezos, Peter; Madden, John D W; Hunter, Ian W

2015-07-01

The large-ion-accessible surface area of carbon nanotubes (CNTs) and graphene sheets formed as yarns, forests, and films enables miniature high-performance supercapacitors with power densities exceeding those of electrolytics while achieving energy densities equaling those of batteries. Capacitance and energy density can be enhanced by depositing highly pseudocapacitive materials such as conductive polymers on them. Yarns formed from carbon nanotubes are proposed for use in wearable supercapacitors. In this work, we show that high power, energy density, and capacitance in yarn form are not unique to carbon materials, and we introduce niobium nanowires as an alternative. These yarns show higher capacitance and energy per volume and are stronger and 100 times more conductive than similarly spun carbon multiwalled nanotube (MWNT) and graphene yarns. The long niobium nanowires, formed by repeated extrusion and drawing, achieve device volumetric peak power and energy densities of 55 MW·m(-3) (55 W·cm(-3)) and 25 MJ·m(-3) (7 mWh·cm(-3)), 2 and 5 times higher than that for state-of-the-art CNT yarns, respectively. The capacitance per volume of Nb nanowire yarn is lower than the 158 MF·m(-3) (158 F·cm(-3)) reported for carbon-based materials such as reduced graphene oxide (RGO) and CNT wet-spun yarns, but the peak power and energy densities are 200 and 2 times higher, respectively. Achieving high power in long yarns is made possible by the high conductivity of the metal, and achievement of high energy density is possible thanks to the high internal surface area. No additional metal backing is needed, unlike for CNT yarns and supercapacitors in general, saving substantial space. As the yarn is infiltrated with pseudocapacitive materials such as poly(3,4-ethylenedioxythiophene) (PEDOT), the energy density is further increased to 10 MJ·m(-3) (2.8 mWh·cm(-3)). Similar to CNT yarns, niobium nanowire yarns are highly flexible and show potential for weaving into textiles

Method for making fine and ultrafine spherical particles of zirconium titanate and other mixed metal oxide systems

DOEpatents

Hu, Michael Z.

2006-05-23

Disclosed is a method for making amorphous spherical particles of zirconium titanate and crystalline spherical particles of zirconium titanate comprising the steps of mixing an aqueous solution of zirconium salt and an aqueous solution of titanium salt into a mixed solution having equal moles of zirconium and titanium and having a total salt concentration in the range from 0.01 M to about 0.5 M. A stearic dispersant and an organic solvent is added to the mixed salt solution, subjecting the zirconium salt and the titanium salt in the mixed solution to a coprecipitation reaction forming a solution containing amorphous spherical particles of zirconium titanate wherein the volume ratio of the organic solvent to aqueous part is in the range from 1 to 5. The solution of amorphous spherical particles is incubated in an oven at a temperature .ltoreq.100.degree. C. for a period of time .ltoreq.24 hours converting the amorphous particles to fine or ultrafine crystalline spherical particles of zirconium titanate.

Application of microdynamics and lattice mechanics to problems in plastic flow and fracture. Final report, 1 April 1973--31 March 1978

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bilello, J C; Liu, J M

Progress in an investigation of the application of microdynamics and lattice mechanics to the problems in plastic flow and fracture is described. The research program consisted of both theoretical formulations and experimental measurements of a number of intrinsic material parameters in bcc metals and alloys including surface energy, phonon-dispersion curves for dislocated solids, dislocation-point defect interaction energy, slip initiation and microplastic flow behavior. The study has resulted in an improved understanding in the relationship among the experimentally determined fracture surface energy, the intrinsic cohesive energy between atomic planes, and the plastic deformation associated with the initial stages of crack propagation.more » The values of intrinsic surface energy of tungsten, molybdenum, niobium and niobium-molybdenum alloys, deduced from the measurements, serve as a starting point from which fracture toughness of these materials in engineering service may be intelligently discussed.« less

Thin film integrated capacitors with sputtered-anodized niobium pentoxide dielectric for decoupling applications

NASA Astrophysics Data System (ADS)

Jacob, Susan

Electronics system miniaturization is a major driver for high-k materials. High-k materials in capacitors allow for high capacitance, enabling system miniaturization. Ta2O5 (k˜24) has been the dominant high-k material in the electronic industry for decoupling capacitors, filter capacitors, etc. In order to facilitate further system miniaturization, this project has investigated thin film integrated capacitors with Nb2O5 dielectric. Nb2O 5 has k˜41 and is a potential candidate for replacing Ta2O5. But, the presence of suboxides (NbO2 and NbO) in the dielectric deteriorates the electrical properties (leakage current, thermal instability of capacitance, etc.). Also, the high oxygen solubility of niobium results in oxygen diffusion from the dielectric to niobium metal, if any is present. The major purpose of this project was to check the ability of NbN as a diffusion barrier and fabricate thermally stable niobium capacitors. As a first step to produce niobium capacitors, the material characterizations of reactively sputtered Nb2O5 and NbN were done. Thickness and film composition, and crystal structures of the sputtered films were obtained and the deposition parameters for the desired stoichiometry were found. Also, anodized Nb2O5 was characterized for its stoichiometry and thickness. To study the effect of nitrides on capacitance and thermal stability, Ta2O5 capacitors were initially fabricated with and without TaN. The results showed that the nitride does not affect the capacitance, and that capacitors with TaN are stable up to 150°C. In the next step, niobium capacitors were first fabricated with anodized dielectric and the oxygen diffusion issues associated with capacitor processing were studied. Reactively sputtered Nb2O5 was anodized to form complete Nb2O5 (with few oxygen vacancies) and NbN was used to sandwich the dielectric. The capacitor fabrication was not successful due to the difficulties in anodizing the sputtered dielectric. Another method, anodizing

METHOD OF FABRICATING A URANIUM-ZIRCONIUM HYDRIDE REACTOR CORE

DOEpatents

Weeks, I.F.; Goeddel, W.V.

1960-03-22

A method is described of evenly dispersing uranlum metal in a zirconium hydride moderator to produce a fuel element for nuclear reactors. According to the invention enriched uranium hydride and zirconium hydride powders of 200 mesh particle size are thoroughly admixed to form a mixture containing 0.1 to 3% by weight of U/sup 235/ hydride. The mixed powders are placed in a die and pressed at 100 tons per square inch at room temperature. The resultant compacts are heated in a vacuum to 300 deg C, whereby the uranium hydride deoomposes into uranium metal and hydrogen gas. The escaping hydrogen gas forms a porous matrix of zirconium hydride, with uramum metal evenly dispersed therethrough. The advantage of the invention is that the porosity and uranium distribution of the final fuel element can be more closely determined and controlled than was possible using prior methods of producing such fuel ele- ments.

Multifilamentary niobium tin magnet conductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Larbalestier, D.C.; Madsen, P.E.; Lee, J.A.

1975-03-01

Practical magnet conductors of multifilamentary Nb$sub 3$Sn have been produced. Evaluation of these bronze route conductors is described. Conductors studied range from a 1369 filament all-bronze matrix conductor to 5143 and approximately 42,000 filament conductors, containing internal high purity copper protected by diffusion barriers. Filament sizes vary from approximately 3 to 8 $mu$m diameter. The effect of heat treatment conditions on critical current and transition temperature is presented and it is shown that overall critical current densities greater than those available in niobium titanium can now be produced in multifilamentary Nb$sub 3$Sn magnet conductor.

Test Result of 650 MHz, Beta 0.61 Single Cell Niobium Cavity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seth, Sudeshna; Bhattacharyya, Pranab; Dutta Gupta, Anjan

VECC has been involved in the design, analysis and development of 650 MHz, beta 0.61 (LB650), elliptical Superconducting RF linac cavity, as part of research and development activities on SRF cavities and associated technologies under Indian Institutions Fermilab Collaboration (IIFC). A single-cell niobium cavity has been indigenously designed and developed at VECC, with the help of Electron Beam Welding (EBW) facility at IUAC, New Delhi. Various measurements, processing and testing at 2K in Vertical Test Stand (VTS) of the single-cell cavity was carried out at ANL and Fermilab, USA, with active participation of VECC engineers. It achieved a maximum acceleratingmore » gradient(Eacc) of 34.5 MV/m with Quality Factor of 2·10⁹ and 30 MV/m with Quality Factor of 1.5·10¹⁰. This is probably the highest accelerating gradient achieved so far in the world for LB650 cavities. This paper describes the design, fabrication and measurement of the single cell niobium cavity. Cavity processing and test results of Vertical Test of the single-cell niobium cavity are also presented.« less

Structural and morphological properties of mesoporous carbon coated molybdenum oxide films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dayal, Saurabh, E-mail: saurabhdayal153@gmail.com; Kumar, C. Sasi, E-mail: csasimv@gmail.com

2016-05-06

In the present study, we report the structural and morphological properties of mesoporous carbon coated molybdenum oxide films. The deposition of films was carried out in a two-step process, the first step involves deposition of molybdenum and carbon bilayer thin films using DC magnetron sputtering. In the second step the sample was ex-situ annealed in a muffle furnace at different temperatures (400°C to 600°C) and air cooled in the ambient atmosphere. The formation of the meso-porous carbon clusters on molybdenum oxide during the cooling step was investigated using FESEM and AFM techniques. The structural details were explored using XRD. Themore » meso-porous carbon were found growing over molybdenum oxide layer as a result of segregation phenomena.« less

Recovering and recycling uranium used for production of molybdenum-99

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reilly, Sean Douglas; May, Iain; Copping, Roy

A processes for recycling uranium that has been used for the production of molybdenum-99 involves irradiating a solution of uranium suitable for forming fission products including molybdenum-99, conditioning the irradiated solution to one suitable for inducing the formation of crystals of uranyl nitrate hydrates, then forming the crystals and a supernatant and then separating the crystals from the supernatant, thus using the crystals as a source of uranium for recycle. Molybdenum-99 is recovered from the supernatant using an adsorbent such as alumina. Another process involves irradiation of a solid target comprising uranium, forming an acidic solution from the irradiated targetmore » suitable for inducing the formation of crystals of uranyl nitrate hydrates, then forming the crystals and a supernatant and then separating the crystals from the supernatant, thus using the crystals as a source of uranium for recycle. Molybdenum-99 is recovered from the supernatant using an adsorbent such as alumina.« less

Loading rate and test temperature effects on fracture of In Situ niobium silicide-niobium composites

NASA Astrophysics Data System (ADS)

Rigney, Joseph D.; Lewandowski, John J.

1996-10-01

Arc cast, extruded, and heat-treated in situ composites of niobium suicide (Nb5Si3) intermetallic with niobium phases (primary—Nbp and secondary—Nbs) exhibited high fracture resistance in comparison to monolithic Nb5Si3. In toughness tests conducted at 298 K and slow applied loading rates, the fracture process proceeded by the microcracking of the Nb5Si3 and plastic deformation of the Nbp and Nbs phases, producing resistance-curve behavior and toughnesses of 28 MPa√m with damage zone lengths less than 500 μm. The effects of changes in the Nbp yield strength and fracture behavior on the measured toughnesses were investigated by varying the loading rates during fracture tests at both 77 and 298 K. Quantitative fractography was utilized to completely characterize each fracture surface created at 298 K in order to determine the type of fracture mode ( i.e., dimpled, cleavage) exhibited by the Nbp. Specimens tested at either higher loading rates or lower test temperatures consistently exhibited a greater amount of cleavage fracture in the Nbp, while the Nbs, always remained ductile. However, the fracture toughness values determined from experiments spanning six orders of magnitude in loading rate at 298 and 77 K exhibited little variation, even under conditions when the majority of Nbp phases failed by cleavage at 77 K. The changes in fracture mode with increasing loading rate and/or decreasing test temperature and their effects on fracture toughness are rationalized by comparison to existing theoretical models.

Molybdenum enhanced low-temperature deposition of crystalline silicon nitride

DOEpatents

Lowden, Richard A.

1994-01-01

A process for chemical vapor deposition of crystalline silicon nitride which comprises the steps of: introducing a mixture of a silicon source, a molybdenum source, a nitrogen source, and a hydrogen source into a vessel containing a suitable substrate; and thermally decomposing the mixture to deposit onto the substrate a coating comprising crystalline silicon nitride containing a dispersion of molybdenum silicide.

Niobium: a rare metal with prospects (in German)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beier, E.

1972-01-01

BS>Important chemical, physical, and mechanical properties of niobium and its alloys arc described. These underline the fact that this highly heat- resistant metal has gained more and more importance in the airplane and spaceship industry as well as in chemical processes and nuclear technology during the last decade. The processing characterization (machining, pressing, and welding) are discussed. (GT)

Extreme diffusion limited electropolishing of niobium radiofrequency cavities

DOE PAGES

Crawford, Anthony C.

2017-01-04

In this study, a deeply modulated, regular, continuous, oscillating current waveform is reliably and repeatably achieved during electropolishing of niobium single-cell elliptical radiofrequency cavities. Details of the technique and cavity test results are reported here. The method is applicable for cavity frequencies in the range 500 MHz to 3.9 GHz and can be extended to multicell structures.

Breaking America's dependence on imported molybdenum.

PubMed

Einstein, Andrew J

2009-03-01

Approximately 9 million nuclear cardiology studies performed each year in the U.S. use technetium-99m, which is produced from the decay of molybdenum-99. The fragility of the worldwide technetium-99m supply chain has been underscored by current shortages caused by an unplanned shutdown of Europe's largest reactor. The majority of the U.S. supply derives from a reactor in Canada that is nearing the end of its lifespan and whose planned replacements have been cancelled recently. In this article, the clinical importance of technetium-99m and our tenuous dependence on the foreign supply of molybdenum are addressed, along with potential measures that may be taken to ensure that America's supply chain remains unbroken.

Two-phase chromium-niobium alloys exhibiting improved mechanical properties at high temperatures

DOEpatents

Liu, C.T.; Takeyama, Masao.

1994-02-01

The specification discloses chromium-niobium alloys which exhibit improved mechanical properties at high temperatures in the range of 1250 C and improved room temperature ductility. The alloys contain a Cr[sub 2]Nb-rich intermetallic phase and a Cr-rich phase with an overall niobium concentration in the range of from about 5 to about 18 at. %. The high temperature strength is substantially greater than that of state of the art nickel-based superalloys for enhanced high temperature service. Further improvements in the properties of the compositions are obtained by alloying with rhenium and aluminum; and additional rare-earth and other elements. 14 figures.

Determination of Activities of Niobium in Cu-Nb Melts Containing Dilute Nb

NASA Astrophysics Data System (ADS)

Wang, Daya; Yan, Baijun; Sichen, Du

2015-04-01

The activity coefficients of niobium in Cu-Nb melts were measured by equilibrating solid NbO2 with liquid copper under controlled oxygen potentials in the temperature range of 1773 K to 1898 K (1500 °C to 1625 °C). Either CO-CO2 gas mixture or H2-CO2 gas mixture was employed to obtain the desired oxygen partial pressures. Cu-Nb system was found to follow Henry's law in the composition range studied. The temperature dependence of Henry's constant in the Cu-Nb melts could be expressed as follows: The partial molar excess Gibbs energy change of niobium in Cu-Nb melts can be expressed as follows:

Fretting wear behavior of zirconium alloy in B-Li water at 300 °C

NASA Astrophysics Data System (ADS)

Zhang, Lefu; Lai, Ping; Liu, Qingdong; Zeng, Qifeng; Lu, Junqiang; Guo, Xianglong

2018-02-01

The tangential fretting wear of three kinds of zirconium alloys tube mated with 304 stainless steel (SS) plate was investigated. The tests were conducted in an autoclave containing 300 °C pressurized B-Li water for tube-on-plate contact configuration. The worn surfaces were examined with scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and 3D microscopy. The cross-section of wear scar was examined with transmission electron microscope (TEM). The results indicated that the dominant wear mechanism of zirconium alloys in this test condition was delamination and oxidation. The oxide layer on the fretted area consists of outer oxide layer composed of iron oxide and zirconium oxide and inner oxide layer composed of zirconium oxide.

Effect of interstitial impurities on the field dependent microwave surface resistance of niobium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martinello, M.; Grassellino, A.; Checchin, M.

Previous work has demonstrated that the radio frequency surface resistance of niobium resonators is dramatically reduced when nitrogen impurities are dissolved as interstitial in the material. The origin of this effect is attributed to the lowering of the Mattis and Bardeen surface resistance contribution with increasing accelerating field. Meanwhile, an enhancement of the sensitivity to trapped magnetic field is typically observed for such cavities. In this paper we conduct the first systematic study on these different components contributing to the total surface resistance as a function of different levels of dissolved nitrogen, in comparison with standard surface treatments for niobiummore » resonators. Adding these results together we are able to show for the first time which is the optimum surface treatment that maximizes the Q-factor of superconducting niobium resonators as a function of expected trapped magnetic field in the cavity walls. Lastly, these results also provide new insights on the physics behind the change in the field dependence of the Mattis and Bardeen surface resistance, and of the trapped magnetic vortex induced losses in superconducting niobium resonators.« less

Effect of interstitial impurities on the field dependent microwave surface resistance of niobium

DOE PAGES

Martinello, M.; Grassellino, A.; Checchin, M.; ...

2016-08-09

Previous work has demonstrated that the radio frequency surface resistance of niobium resonators is dramatically reduced when nitrogen impurities are dissolved as interstitial in the material. The origin of this effect is attributed to the lowering of the Mattis and Bardeen surface resistance contribution with increasing accelerating field. Meanwhile, an enhancement of the sensitivity to trapped magnetic field is typically observed for such cavities. In this paper we conduct the first systematic study on these different components contributing to the total surface resistance as a function of different levels of dissolved nitrogen, in comparison with standard surface treatments for niobiummore » resonators. Adding these results together we are able to show for the first time which is the optimum surface treatment that maximizes the Q-factor of superconducting niobium resonators as a function of expected trapped magnetic field in the cavity walls. Lastly, these results also provide new insights on the physics behind the change in the field dependence of the Mattis and Bardeen surface resistance, and of the trapped magnetic vortex induced losses in superconducting niobium resonators.« less

40 CFR 721.10152 - Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4+) salt and silica...

Code of Federal Regulations, 2010 CFR

2010-07-01

...-, hydrolysis products with alkanol zirconium(4+) salt and silica, acetates (generic). 721.10152 Section 721... Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4+) salt and silica... zirconium(4+) salt and silica, acetates (PMN P-07-674) is subject to reporting under this section for the...

Reduced-Gravity Measurements of the Effect of Oxygen on Properties of Zirconium

NASA Technical Reports Server (NTRS)

Zhao, J.; Lee, J.; Wunderlich, R.; Fecht, H.-J.; Schneider, S.; SanSoucie, M.; Rogers, J.; Hyers, R.

2016-01-01

The influence of oxygen on the thermophysical properties of zirconium is being investigated using MSL-EML (Material Science Laboratory - Electromagnetic Levitator) on ISS (International Space Station) in collaboration with NASA, ESA (European Space Agency), and DLR (German Aerospace Center). Zirconium samples with different oxygen concentrations will be put into multiple melt cycles, during which the density, viscosity, surface tension, heat capacity, and electric conductivity will be measured at various undercooled temperatures. The facility check-up of MSL-EML and the first set of melting experiments have been successfully performed in 2015. The first zirconium sample will be tested near the end of 2015. As part of ground support activities, the thermophysical properties of zirconium and ZrO were measured using a ground-based electrostatic levitator located at the NASA Marshall Space Flight Center. The influence of oxygen on the measured surface tension was evaluated. The results of this research will serve as reference data for those measured in ISS.

An improved oxygen diffusion model to explain the effect of low-temperature baking on high field losses in niobium superconducting cavities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ciovati, Gianluigi

Radio-frequency (RF) superconducting cavities made of high purity niobium are widely used to accelerate charged particle beams in particle accelerators. The major limitation to achieve RF field values approaching the theoretical limit for niobium is represented by ''anomalous'' losses which degrade the quality factor of the cavities starting at peak surface magnetic fields of about 100 mT, in absence of field emission. These high field losses are often referred to as ''Q-drop''. It has been observed that the Q-drop is drastically reduced by baking the cavities at 120 C for about 48 h under ultrahigh vacuum. An improved oxygen diffusionmore » model for the niobium-oxide system is proposed to explain the benefit of the low-temperature baking on the Q-drop in niobium superconducting rf cavities. The model shows that baking at 120 C for 48 h allows oxygen to diffuse away from the surface, and therefore increasing the lower critical field towards the value for pure niobium.« less

Aqueous sodium borohydride induced thermally stable porous zirconium oxide for quick removal of lead ions

PubMed Central

Nayak, Nadiya B.; Nayak, Bibhuti B.

2016-01-01

Aqueous sodium borohydride (NaBH4) is well known for its reducing property and well-established for the development of metal nanoparticles through reduction method. In contrary, this research paper discloses the importance of aqueous NaBH4 as a precipitating agent towards development of porous zirconium oxide. The boron species present in aqueous NaBH4 play an active role during gelation as well as phase separated out in the form of boron complex during precipitation, which helps to form boron free zirconium hydroxide [Zr(OH)4] in the as-synthesized condition. Evolved in-situ hydrogen (H2) gas-bubbles also play an important role to develop as-synthesized loose zirconium hydroxide and the presence of intra-particle voids in the loose zirconium hydroxide help to develop porous zirconium oxide during calcination process. Without any surface modification, this porous zirconium oxide quickly adsorbs almost hundred percentages of toxic lead ions from water solution within 15 minutes at normal pH condition. Adsorption kinetic models suggest that the adsorption process was surface reaction controlled chemisorption. Quick adsorption was governed by surface diffusion process and the adsorption kinetic was limited by pore diffusion. Five cycles of adsorption-desorption result suggests that the porous zirconium oxide can be reused efficiently for removal of Pb (II) ions from aqueous solution. PMID:26980545

High-strength, creep-resistant molybdenum alloy and process for producing the same

DOEpatents

Bianco, Robert; Buckman, Jr., R. William; Geller, Clint B.

1999-01-01

A wet-doping process for producing an oxide-dispersion strengthened (ODS), creep-resistant molybdenum alloy is disclosed. The alloy is made by adding nitrate or acetate salts of lanthanum, cerium, thorium, or yttrium to molybdenum oxide to produce a slurry, heating the slurry in a hydrogen atmosphere to produce a powder, mixing and cold isostatically pressing the powder, sintering in a hydrogen atmosphere, and thermomechanically processing (swaging, extruding, cold drawing) the product. The ODS molybdenum alloy produced by the process contains 2-4% by volume (.about.1-4% by weight) of an oxide of lanthanum, cerium, thorium, or yttrium. The alloy has high strength and improved creep-resistance at temperatures greater than 0.55T.sub.m of molybdenum.

10 CFR 30.72 - Schedule C-Quantities of radioactive materials requiring consideration of the need for an...

Code of Federal Regulations, 2011 CFR

2011-01-01

... Molybdenum-99 .01 30,000 Neptunium-237 .001 2 Nickel-63 .01 20,000 Niobium-94 .01 300 Phosphorus-32 .5 100 Phosphorus-33 .5 1,000 Polonium-210 .01 10 Potassium-42 .01 9,000 Promethium-145 .01 4,000 Promethium-147 .01...

10 CFR 30.72 - Schedule C-Quantities of radioactive materials requiring consideration of the need for an...

Code of Federal Regulations, 2010 CFR

2010-01-01

... Molybdenum-99 .01 30,000 Neptunium-237 .001 2 Nickel-63 .01 20,000 Niobium-94 .01 300 Phosphorus-32 .5 100 Phosphorus-33 .5 1,000 Polonium-210 .01 10 Potassium-42 .01 9,000 Promethium-145 .01 4,000 Promethium-147 .01...

48 CFR 252.225-7008 - Restriction on Acquisition of Specialty Metals.

Code of Federal Regulations, 2013 CFR

2013-10-01

... consolidation of non-melt derived metal powders. Specialty metal means— (i) Steel— (A) With a maximum alloy..., chromium, cobalt, molybdenum, nickel, niobium (columbium), titanium, tungsten, or vanadium; (ii) Metal... of Specialty Metals. 252.225-7008 Section 252.225-7008 Federal Acquisition Regulations System DEFENSE...

48 CFR 252.225-7008 - Restriction on Acquisition of Specialty Metals.

Code of Federal Regulations, 2014 CFR

2014-10-01

... consolidation of non-melt derived metal powders. Specialty metal means— (i) Steel— (A) With a maximum alloy..., chromium, cobalt, molybdenum, nickel, niobium (columbium), titanium, tungsten, or vanadium; (ii) Metal... of Specialty Metals. 252.225-7008 Section 252.225-7008 Federal Acquisition Regulations System DEFENSE...

DFT study of the molybdenum-catalyzed deoxydehydration of vicinal diols.

PubMed

Lupp, Daniel; Christensen, Niels Johan; Dethlefsen, Johannes R; Fristrup, Peter

2015-02-16

The mechanism of the molybdenum-catalyzed deoxydehydration (DODH) of vicinal diols has been investigated using density functional theory. The proposed catalytic cycle involves condensation of the diol with an Mo(VI) oxo complex, oxidative cleavage of the diol resulting in an Mo(IV) complex, and extrusion of the alkene. We have compared the proposed pathway with several alternatives, and the results have been corroborated by comparison with the molybdenum-catalyzed sulfoxide reduction recently published by Sanz et al. and with experimental observations for the DODH itself. Improved understanding of the mechanism should expedite future optimization of molybdenum-catalyzed biomass transformations. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Astrocyte dysfunction following molybdenum-associated purine loading could initiate Parkinson's disease with dementia.

PubMed

Bourke, Christopher A

2018-01-01

Sporadic or idiopathic Parkinson's disease is a movement disorder with a worldwide distribution, a long pre-clinical latent period and a frequent association with dementia. The combination of molybdenum deficiency and purine ingestion could explain the movement disorder, the distribution, the latent period and the dementia association. Recent studies in sheep have shown that molybdenum deficiency enables some dietary purines to accumulate in the central nervous system. This causes astrocyte dysfunction, altered neuromodulation and eventually irreversible central nervous system disease. Humans and sheep share the ability to salvage purines and this ability places humans at risk when they ingest xanthosine, inosine, adenosine and guanosine. Adenosine ingestion in molybdenum-deficient humans will lead to adenosine loading and potentially a disturbance to the A2a adenosine receptors in the nigro-striatum. This could result in Parkinson's disease. Guanosine ingestion in molybdenum-deficient humans will lead to guanosine loading and potentially a disturbance to the guanosine receptors in the hippocampus, amygdala and ventral striatum. This could result in dementia. The molybdenum content of the average daily diet in the United States is 0.07 ppm and in the United Kingdom 0.04 ppm. Central nervous system disease occurs in sheep at <0.04 ppm. Consistent with the role proposed for molybdenum deficiency in Parkinson's disease is the observation that affected individuals have elevated sulfur amino acid levels, depressed sulfate levels, and depressed uric acid levels. Likewise the geographical distribution of Parkinson's dementia complex on Guam corresponds with the distribution of molybdenum-deficient soils hence molybdenum-deficient food gardens on that island.

Bayesian model selection validates a biokinetic model for zirconium processing in humans

PubMed Central

2012-01-01

Background In radiation protection, biokinetic models for zirconium processing are of crucial importance in dose estimation and further risk analysis for humans exposed to this radioactive substance. They provide limiting values of detrimental effects and build the basis for applications in internal dosimetry, the prediction for radioactive zirconium retention in various organs as well as retrospective dosimetry. Multi-compartmental models are the tool of choice for simulating the processing of zirconium. Although easily interpretable, determining the exact compartment structure and interaction mechanisms is generally daunting. In the context of observing the dynamics of multiple compartments, Bayesian methods provide efficient tools for model inference and selection. Results We are the first to apply a Markov chain Monte Carlo approach to compute Bayes factors for the evaluation of two competing models for zirconium processing in the human body after ingestion. Based on in vivo measurements of human plasma and urine levels we were able to show that a recently published model is superior to the standard model of the International Commission on Radiological Protection. The Bayes factors were estimated by means of the numerically stable thermodynamic integration in combination with a recently developed copula-based Metropolis-Hastings sampler. Conclusions In contrast to the standard model the novel model predicts lower accretion of zirconium in bones. This results in lower levels of noxious doses for exposed individuals. Moreover, the Bayesian approach allows for retrospective dose assessment, including credible intervals for the initially ingested zirconium, in a significantly more reliable fashion than previously possible. All methods presented here are readily applicable to many modeling tasks in systems biology. PMID:22863152

Molybdenum enhanced low-temperature deposition of crystalline silicon nitride

DOEpatents

Lowden, R.A.

1994-04-05

A process for chemical vapor deposition of crystalline silicon nitride is described which comprises the steps of: introducing a mixture of a silicon source, a molybdenum source, a nitrogen source, and a hydrogen source into a vessel containing a suitable substrate; and thermally decomposing the mixture to deposit onto the substrate a coating comprising crystalline silicon nitride containing a dispersion of molybdenum silicide. 5 figures.

Influence of Soil Solution Salinity on Molybdenum Adsorption by Soils

USDA-ARS?s Scientific Manuscript database

Molybdenum (Mo) adsorption on five arid-zone soils from California was investigated as a function of equilibrium solution Mo concentration (0-30 mg L-1), solution pH (4-8), and electrical conductivity (EC = 0.3 or 8 dS m-1). Molybdenum adsorption decreased with increasing pH. An adsorption maximum...

SEPARATION OF FISSION PRODUCT VALUES FROM THE HEXAVALENT PLUTONIUM BY CARRIER PRECIPITATION

DOEpatents

Davies, T.H.

1959-12-15

An improved precipitation of fission products on bismuth phosphate from an aqueous mineral acid solution also containing hexavalent plutonium by incorporating, prior to bismuth phosphate precipitation, from 0.05 to 2.5 grams/ liter of zirconium phosphate, niobium oxide. and/or lanthanum fluoride is described. The plutonium remains in solution.

Ideal strength of bcc molybdenum and niobium

NASA Astrophysics Data System (ADS)

Luo, Weidong; Roundy, D.; Cohen, Marvin L.; Morris, J. W.

2002-09-01

The behavior of bcc Mo and Nb under large strain was investigated using the ab initio pseudopotential density-functional method. We calculated the ideal shear strength for the {211}<111> and {011}<111> slip systems and the ideal tensile strength in the <100> direction, which are believed to provide the minimum shear and tensile strengths. As either material is sheared in either of the two systems, it evolves toward a stress-free tetragonal structure that defines a saddle point in the strain-energy surface. The inflection point on the path to this tetragonal ``saddle-point'' structure sets the ideal shear strength. When either material is strained in tension along <100>, it initially follows the tetragonal, ``Bain,'' path toward a stress-free fcc structure. However, before the strained crystal reaches fcc, its symmetry changes from tetragonal to orthorhombic; on continued strain it evolves toward the same tetragonal saddle point that is reached in shear. In Mo, the symmetry break occurs after the point of maximum tensile stress has been passed, so the ideal strength is associated with the fcc extremum as in W. However, a Nb crystal strained in <100> becomes orthorhombic at tensile stress below the ideal strength. The ideal tensile strength of Nb is associated with the tetragonal saddle point and is caused by failure in shear rather than tension. In dimensionless form, the ideal shear and tensile strengths of Mo (τ*=τm/G111=0.12, σ*=σm/E100=0.078) are essentially identical to those previously calculated for W. Nb is anomalous. Its dimensionless shear strength is unusually high, τ*=0.15, even though the saddle-point structure that causes it is similar to that in Mo and W, while its dimensionless tensile strength, σ*=0.079, is almost the same as that of Mo and W, even though the saddle-point structure is quite different.

Bragg projection ptychography on niobium phase domain

DOE PAGES

Burdet, Nicolas; Shi, Xiaowen; Huang, Xiaojing; ...

2016-08-10

Here, we demonstrate that the highly sensitive phase-contrast properties of Bragg coherent diffraction measurements combined with the translational diversity of ptychography can provide a Bragg “dark field” imaging method capable of revealing the finger print of domain structure in metallic thin films. Experimental diffraction data was taken from a epitaxially grown niobium metallic thin film on sapphire; and analyzed with the help of a careful combination of implemented refinement mechanisms.

Microstructures define melting of molybdenum at high pressures

NASA Astrophysics Data System (ADS)

Hrubiak, Rostislav; Meng, Yue; Shen, Guoyin

2017-03-01

High-pressure melting anchors the phase diagram of a material, revealing the effect of pressure on the breakdown of the ordering of atoms in the solid. An important case is molybdenum, which has long been speculated to undergo an exceptionally steep increase in melting temperature when compressed. On the other hand, previous experiments showed nearly constant melting temperature as a function of pressure, in large discrepancy with theoretical expectations. Here we report a high-slope melting curve in molybdenum by synchrotron X-ray diffraction analysis of crystalline microstructures, generated by heating and subsequently rapidly quenching samples in a laser-heated diamond anvil cell. Distinct microstructural changes, observed at pressures up to 130 gigapascals, appear exclusively after melting, thus offering a reliable melting criterion. In addition, our study reveals a previously unsuspected transition in molybdenum at high pressure and high temperature, which yields highly textured body-centred cubic nanograins above a transition temperature.

Microstructures define melting of molybdenum at high pressures

PubMed Central

Hrubiak, Rostislav; Meng, Yue; Shen, Guoyin

2017-01-01

High-pressure melting anchors the phase diagram of a material, revealing the effect of pressure on the breakdown of the ordering of atoms in the solid. An important case is molybdenum, which has long been speculated to undergo an exceptionally steep increase in melting temperature when compressed. On the other hand, previous experiments showed nearly constant melting temperature as a function of pressure, in large discrepancy with theoretical expectations. Here we report a high-slope melting curve in molybdenum by synchrotron X-ray diffraction analysis of crystalline microstructures, generated by heating and subsequently rapidly quenching samples in a laser-heated diamond anvil cell. Distinct microstructural changes, observed at pressures up to 130 gigapascals, appear exclusively after melting, thus offering a reliable melting criterion. In addition, our study reveals a previously unsuspected transition in molybdenum at high pressure and high temperature, which yields highly textured body-centred cubic nanograins above a transition temperature. PMID:28248309

Application of laser-induced breakdown spectroscopy to zirconium in aqueous solution

NASA Astrophysics Data System (ADS)

Ruas, Alexandre; Matsumoto, Ayumu; Ohba, Hironori; Akaoka, Katsuaki; Wakaida, Ikuo

2017-05-01

In the context of the Fukushima Dai-ichi Nuclear Power Plant (F1-NPP) decommissioning process, laser-induced breakdown spectroscopy (LIBS) has many advantages. The purpose of the present work is to demonstrate the on-line monitoring capability of the LIBS coupled with the ultra-thin liquid jet sampling method. The study focuses on zirconium in aqueous solution, considering that it is a major element in the F1-NPP fuel debris that has been subject to only a few LIBS studies in the past. The methodology of data acquisition and processing are described. In particular, two regions of interest with many high intensity zirconium lines have been observed around 350 nm in the case of the ionic lines and 478 nm in the case of atomic lines. The best analytical conditions for zirconium are different depending on the analysis of ionic lines or atomic lines. A low LOD of about 4 mg L- 1 could be obtained, showing that LIBS coupled with the ultra-thin liquid jet sampling technique is a promising alternative for more complex solutions found in the F1-NPP, namely mixtures containing zirconium.

Clinical Outcomes of Zirconium-Oxide Posts: Up-to-Date Systematic Review.

PubMed

Al-Thobity, Ahmad M

2016-06-01

The aim of this systematic review was to investigate the clinical outcomes of the use of zirconium-oxide posts in the past 20 years. The addressed question was: Do zirconium-oxide posts maintain the long-term survival rate of endodontically treated teeth? A database search was made of articles from January 1995 to December 2014; it included combinations of the following keywords: "zirconia," "zirconium oxide," "dowel/dowels," "post/posts," and "post and core." Exclusion criteria included review articles, experimental studies, case reports, commentaries, and articles published in a language other than English. Articles were reviewed by the titles, followed by the abstracts, and, finally, the full text of the selected studies. Four studies were included after filtering the selected studies according to the inclusion and exclusion criteria. In one study, the prefabricated zirconia posts with indirect glass-ceramic cores had significantly higher failure rates than other posts with direct composite cores. In two studies, no failure of the cemented posts was observed throughout the follow-up period. Due to the limited number of clinical studies, it can be concluded that the long-term success rate of prefabricated zirconium-oxide posts is unclear.

Five year survival analysis of an oxidised zirconium total knee arthroplasty.

PubMed

Holland, Philip; Santini, Alasdair J A; Davidson, John S; Pope, Jill A

2013-12-01

Zirconium total knee arthroplasties theoretically have a low incidence of failure as they are low friction, hard wearing and hypoallergenic. We report the five year survival of 213 Profix zirconium total knee arthroplasties with a conforming all polyethylene tibial component. Data was collected prospectively and multiple strict end points were used. SF12 and WOMAC scores were recorded pre-operatively, at three months, at twelve months, at 3 years and at 5 years. Eight patients died and six were "lost to follow-up". The remaining 199 knees were followed up for five years. The mean WOMAC score improved from 56 to 35 and the mean SF12 physical component score improved from 28 to 34. The five year survival for failure due to implant related reasons was 99.5% (95% CI 97.4-100). This was due to one tibial component becoming loose aseptically in year zero. Our results demonstrate that the Profix zirconium total knee arthroplasty has a low medium term failure rate comparable to the best implants. Further research is needed to establish if the beneficial properties of zirconium improve long term implant survival. Copyright © 2012 Elsevier B.V. All rights reserved.

Atomic layer deposition of zirconium silicate films using zirconium tetra-tert-butoxide and silicon tetrachloride

NASA Astrophysics Data System (ADS)

Kim, Won-Kyu; Kang, Sang-Woo; Rhee, Shi-Woo

2003-09-01

A new precursor combination (SiCl4 and Zr(OtC4H9)4) was used to deposit Zr silicate with Zr(OtC4H9)4 as a zirconium source and oxygen source at the same time. SiCl4 and Zr(OtC4H9)4 have higher vapor pressures than their counterpart, ZrCl4 and tetra-n-butyl orthosilicate (TBOS), and it was expected that the cycle time would be shorter. The deposition temperature of the new combination was about 150 °C lower than that of ZrCl4 and TBOS. The film was zirconium rich while it was silicon rich with ZrCl4 and TBOS. Growth rate (nm/cycle), composition ratio [Zr/(Zr+Si)], and chlorine impurity were decreased with increasing deposition temperature from 125 to 225 °C. The composition ratio of the film deposited at 225 °C was 0.53 and the chlorine content was about 0.4 at. %. No carbon was detected by x-ray photoelectron spectroscopy.

SURFACE TREATMENT OF MOLYBDENUM METAL

DOEpatents

Coffer, C.O.

1961-12-01

A process of descaling molybdenum articles comprises first immersing them in an aqueous sodium hydroxide-potassium permanganate solution of between 60 and 85 deg C, rinsing, and then immersing them in an aqueous solution containing a mixture of sulfuric, hydrochloric, and chromic acids.

High-strength, creep-resistant molybdenum alloy and process for producing the same

DOEpatents

Bianco, R.; Buckman, R.W. Jr.; Geller, C.B.

1999-02-09

A wet-doping process for producing an oxide-dispersion strengthened (ODS), creep-resistant molybdenum alloy is disclosed. The alloy is made by adding nitrate or acetate salts of lanthanum, cerium, thorium, or yttrium to molybdenum oxide to produce a slurry, heating the slurry in a hydrogen atmosphere to produce a powder, mixing and cold isostatically pressing the powder, sintering in a hydrogen atmosphere, and thermomechanically processing (swaging, extruding, cold drawing) the product. The ODS molybdenum alloy produced by the process contains 2--4% by volume (ca. 1--4% by weight) of an oxide of lanthanum, cerium, thorium, or yttrium. The alloy has high strength and improved creep-resistance at temperatures greater than 0.55T{sub m} of molybdenum. 10 figs.

Shear Bond Strength of Orthodontic Brackets Bonded to Zirconium Crowns

PubMed Central

Mehmeti, Blerim; Azizi, Bleron; Kelmendi, Jeta; Iljazi-Shahiqi, Donika; Alar, Željko

2017-01-01

Background An increasing demand for esthetic restorations has resulted in an increased use of all-ceramic restorations, such as zirconium. However, one of the challenges the orthodontist must be willing to face is how to increase bond strength between the brackets and various ceramic restorations.Bond strength can beaffected bybracket type, by the material that bracketsaremade of, and their base surface design or retention mode. ​ Aim: of this study was to perform a comparative analysis of the shear bond strength (SBS) of metallic and ceramic orthodontic brackets bonded to all-zirconium ceramic surfaces used for prosthetic restorations, and also to evaluate the fracture mode of these two types of orthodontic brackets. Material and methods Twenty samples/semi-crowns of all-zirconium ceramic, on which orthodontic brackets were bonded, 10 metallic and 10 ceramic polycrystalline brackets, were prepared for this research. SBS has been testedby Universal Testing Machine, with a load applied using a knife edged rod moving at a fixed rate of 1 mm/min, until failure occurred. The force required to debond the brackets was recorded in Newton, then SBS was calculated to MPa. In addition, the samples were analyzed using a digital camera magnifier to determine Adhesive Remnant Index (ARI). Statistical data were processed using t-test, and the level of significance was set at α = 0.05. Results Higher shear bond strength values were observed in metallic brackets bonded to zirconium crowns compared tothoseof ceramic brackets, with a significant difference. During the test, two of the ceramic brackets were partially or totally damaged. Conclusion Metallic brackets, compared to ceramic polycrystalline brackets, seemed tocreate stronger adhesion with all-zirconium surfaces due to their better retention mode. Also, ceramic brackets showed higher fragility during debonding. PMID:28827846

Shear Bond Strength of Orthodontic Brackets Bonded to Zirconium Crowns.

PubMed

Mehmeti, Blerim; Azizi, Bleron; Kelmendi, Jeta; Iljazi-Shahiqi, Donika; Alar, Željko; Anić-Milošević, Sandra

2017-06-01

An increasing demand for esthetic restorations has resulted in an increased use of all-ceramic restorations, such as zirconium. However, one of the challenges the orthodontist must be willing to face is how to increase bond strength between the brackets and various ceramic restorations.Bond strength can beaffected bybracket type, by the material that bracketsaremade of, and their base surface design or retention mode. ​: A im: of this study was to perform a comparative analysis of the shear bond strength (SBS) of metallic and ceramic orthodontic brackets bonded to all-zirconium ceramic surfaces used for prosthetic restorations, and also to evaluate the fracture mode of these two types of orthodontic brackets. Twenty samples/semi-crowns of all-zirconium ceramic, on which orthodontic brackets were bonded, 10 metallic and 10 ceramic polycrystalline brackets, were prepared for this research. SBS has been testedby Universal Testing Machine, with a load applied using a knife edged rod moving at a fixed rate of 1 mm/min, until failure occurred. The force required to debond the brackets was recorded in Newton, then SBS was calculated to MPa. In addition, the samples were analyzed using a digital camera magnifier to determine Adhesive Remnant Index (ARI). Statistical data were processed using t-test, and the level of significance was set at α = 0.05. Higher shear bond strength values were observed in metallic brackets bonded to zirconium crowns compared tothoseof ceramic brackets, with a significant difference. During the test, two of the ceramic brackets were partially or totally damaged. Metallic brackets, compared to ceramic polycrystalline brackets, seemed tocreate stronger adhesion with all-zirconium surfaces due to their better retention mode. Also, ceramic brackets showed higher fragility during debonding.

Mechanical properties of zirconium alloys and zirconium hydrides predicted from density functional perturbation theory

DOE PAGES

Weck, Philippe F.; Kim, Eunja; Tikare, Veena; ...

2015-10-13

Here, the elastic properties and mechanical stability of zirconium alloys and zirconium hydrides have been investigated within the framework of density functional perturbation theory. Results show that the lowest-energy cubic Pn-3m with combining macron]m polymorph of δ-ZrH 1.5 does not satisfy all the Born requirements for mechanical stability, unlike its nearly degenerate tetragonal P4 2/ mcm polymorph. Elastic moduli predicted with the Voigt–Reuss–Hill approximations suggest that mechanical stability of α-Zr, Zr-alloy and Zr-hydride polycrystalline aggregates is limited by the shear modulus. According to both Pugh's and Poisson's ratios, α-Zr, Zr-alloy and Zr-hydride polycrystalline aggregates can be considered ductile. The Debyemore » temperatures predicted for γ-ZrH, δ-ZrH 1.5 and ε-ZrH 2 are θ D = 299.7, 415.6 and 356.9 K, respectively, while θ D = 273.6, 284.2, 264.1 and 257.1 K for the α-Zr, Zry-4, ZIRLO and M5 matrices, i.e. suggesting that Zry-4 possesses the highest micro-hardness among Zr matrices.« less

Inhibition of Ice Growth and Recrystallization by Zirconium Acetate and Zirconium Acetate Hydroxide

PubMed Central

Mizrahy, Ortal; Bar-Dolev, Maya; Guy, Shlomit; Braslavsky, Ido

2013-01-01

The control over ice crystal growth, melting, and shaping is important in a variety of fields, including cell and food preservation and ice templating for the production of composite materials. Control over ice growth remains a challenge in industry, and the demand for new cryoprotectants is high. Naturally occurring cryoprotectants, such as antifreeze proteins (AFPs), present one solution for modulating ice crystal growth; however, the production of AFPs is expensive and inefficient. These obstacles can be overcome by identifying synthetic substitutes with similar AFP properties. Zirconium acetate (ZRA) was recently found to induce the formation of hexagonal cavities in materials prepared by ice templating. Here, we continue this line of study and examine the effects of ZRA and a related compound, zirconium acetate hydroxide (ZRAH), on ice growth, shaping, and recrystallization. We found that the growth rate of ice crystals was significantly reduced in the presence of ZRA and ZRAH, and that solutions containing these compounds display a small degree of thermal hysteresis, depending on the solution pH. The compounds were found to inhibit recrystallization in a manner similar to that observed in the presence of AFPs. The favorable properties of ZRA and ZRAH suggest tremendous potential utility in industrial applications. PMID:23555701

Design and development of novel MRI compatible zirconium- ruthenium alloys with ultralow magnetic susceptibility.

PubMed

Li, H F; Zhou, F Y; Li, L; Zheng, Y F

2016-04-19

In the present study, novel MRI compatible zirconium-ruthenium alloys with ultralow magnetic susceptibility were developed for biomedical and therapeutic devices under MRI diagnostics environments. The results demonstrated that alloying with ruthenium into pure zirconium would significantly increase the strength and hardness properties. The corrosion resistance of zirconium-ruthenium alloys increased significantly. High cell viability could be found and healthy cell morphology observed when culturing MG 63 osteoblast-like cells and L-929 fibroblast cells with zirconium-ruthenium alloys, whereas the hemolysis rates of zirconium-ruthenium alloys are <1%, much lower than 5%, the safe value for biomaterials according to ISO 10993-4 standard. Compared with conventional biomedical 316L stainless steel, Co-Cr alloys and Ti-based alloys, the magnetic susceptibilities of the zirconium-ruthenium alloys (1.25 × 10(-6) cm(3)·g(-1)-1.29 × 10(-6) cm(3)·g(-1) for zirconium-ruthenium alloys) are ultralow, about one-third that of Ti-based alloys (Ti-6Al-4V, ~3.5 × 10(-6) cm(3)·g(-1), CP Ti and Ti-6Al-7Nb, ~3.0 × 10(-6) cm(3)·g(-1)), and one-sixth that of Co-Cr alloys (Co-Cr-Mo, ~7.7 × 10(-6) cm(3)·g(-1)). Among the Zr-Ru alloy series, Zr-1Ru demonstrates enhanced mechanical properties, excellent corrosion resistance and cell viability with lowest magnetic susceptibility, and thus is the optimal Zr-Ru alloy system as therapeutic devices under MRI diagnostics environments.

Bioactivity and biocompatibility of hydroxyapatite-based bioceramic coatings on zirconium by plasma electrolytic oxidation.

PubMed

Aktuğ, Salim Levent; Durdu, Salih; Yalçın, Emine; Çavuşoğlu, Kültigin; Usta, Metin

2017-02-01

In the present work, hydroxyapatite (HAP)-based plasma electrolytic oxide (PEO) coatings were produced on zirconium at different current densities in a solution containing calcium acetate and β-calcium glycerophosphate by a single step. The phase structure, surface morphology, functional groups, thickness and roughness of the coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), eddy current method and surface profilometer, respectively. The phases of cubic-zirconia, calcium zirconate and HAP were detected by XRD. The amount of HAP and calcium zirconate increased with increasing current density. The surface of the coatings was very porous and rough. Moreover, bioactivity and biocompatibility of the coatings were analyzed in vitro immersion simulated body fluid (SBF) and MTT (3-(4,5-dimethyl thiazol-2yl)-2,5-diphenyl tetrazolium bromide) assay, hemolysis assay and bacterial formation. The apatite-forming ability of the coatings was evaluated after immersion in SBF up to 28days. After immersion, the bioactivity of HAP-based coatings on zirconium was greater than the ones of uncoated zirconium and zirconium oxide-based surface. The bioactivity of PEO surface on zirconium was significantly improved under SBF conditions. The bacterial adhesion of the coatings decreased with increasing current density. The bacterial adhesion of the coating produced at 0.370A/cm 2 was minimum compared to uncoated zirconium coated at 0.260 and 0.292A/cm 2 . The hemocompatibility of HAP-based surfaces was improved by PEO. The cell attachment and proliferation of the PEO coatings were better than the one of uncoated zirconium according to MTT assay results. Copyright © 2016 Elsevier B.V. All rights reserved.

Design and development of novel MRI compatible zirconium- ruthenium alloys with ultralow magnetic susceptibility

PubMed Central

Li, H.F.; Zhou, F.Y.; Li, L.; Zheng, Y.F.

2016-01-01

In the present study, novel MRI compatible zirconium-ruthenium alloys with ultralow magnetic susceptibility were developed for biomedical and therapeutic devices under MRI diagnostics environments. The results demonstrated that alloying with ruthenium into pure zirconium would significantly increase the strength and hardness properties. The corrosion resistance of zirconium-ruthenium alloys increased significantly. High cell viability could be found and healthy cell morphology observed when culturing MG 63 osteoblast-like cells and L-929 fibroblast cells with zirconium-ruthenium alloys, whereas the hemolysis rates of zirconium-ruthenium alloys are <1%, much lower than 5%, the safe value for biomaterials according to ISO 10993-4 standard. Compared with conventional biomedical 316L stainless steel, Co–Cr alloys and Ti-based alloys, the magnetic susceptibilities of the zirconium-ruthenium alloys (1.25 × 10−6 cm3·g−1–1.29 × 10−6 cm3·g−1 for zirconium-ruthenium alloys) are ultralow, about one-third that of Ti-based alloys (Ti–6Al–4V, ~3.5 × 10−6 cm3·g−1, CP Ti and Ti–6Al–7Nb, ~3.0 × 10−6 cm3·g−1), and one-sixth that of Co–Cr alloys (Co–Cr–Mo, ~7.7 × 10−6 cm3·g−1). Among the Zr–Ru alloy series, Zr–1Ru demonstrates enhanced mechanical properties, excellent corrosion resistance and cell viability with lowest magnetic susceptibility, and thus is the optimal Zr–Ru alloy system as therapeutic devices under MRI diagnostics environments. PMID:27090955

Ferrier rearrangement promoted by an electrochemically generated zirconium catalyst.

PubMed

Stevanović, Dragana; Pejović, Anka; Damljanović, Ivan; Minić, Aleksandra; Bogdanović, Goran A; Vukićević, Mirjana; Radulović, Niko S; Vukićević, Rastko D

2015-04-30

In situ generated zirconium catalyst from a sacrificial zirconium anode was successfully applied to promote Ferrier rearrangement of 3,4,5-tri-O-acetyl-D-glucal and 6-deoxy-3,4-di-O-acetyl-L-glucal (3,4-di-O-acetyl-L-rhamnal) in the presence of three thiols and eleven thiophenols as nucleophiles. A simple constant current electrolysis (20 mA, 0.4 F mol(-1)) of an acetonitrile solution of lithium perchlorate (0.1 M) containing the corresponding glycal and S-nucleophiles, using a zirconium anode and a platinum cathode resulted in the successful synthesis of the corresponding 2,3-unsaturated peracetylated thioglycosides (with an average anomer ratio α/β=4.129 in the case of peracetylated D-glucal and 8.740 in the case of L-rhamnal). The same procedure proved to be appropriate in synthesizing dihydropyran derivatives ('C-glycosides') using allyltrimethylsilane as the nucleophile (only 'α-anomers' were obtained). All new compounds were fully characterized by spectral data, whereas single-crystal X-ray analysis was performed for two thioglycosides. Copyright © 2015 Elsevier Ltd. All rights reserved.

Molybdenum nitrides as oxygen reduction reaction catalysts: Structural and electrochemical studies

DOE PAGES

Cao, Bingfei; Neuefeind, Joerg C.; Adzic, Radoslav R.; ...

2015-02-09

Monometallic (δ-MoN, Mo 5N 6, and Mo 2N) and bimetallic molybdenum nitrides (Co 0.6Mo 1.4N 2) were investigated as electrocatalysts for the oxygen reduction reaction (ORR), which is a key half-reaction in hydrogen fuel cells. Monometallic hexagonal molybdenum nitrides are found to exhibit improved activities over rock salt type molybdenum nitride (γ-Mo 2N), suggesting that improvements are due to either the higher molybdenum valence or a more favorable coordination environment in the hexagonal structures. Further enhancements in activity were found for hexagonal bimetallic cobalt molybdenum nitride (Co 0.6Mo 1.4N 2), resulting in a modest onset potential of 0.713 V versusmore » reversible hydrogen electrode (RHE). Co 0.6Mo 1.4N 2 exhibits good stability in acidic environments, and in the potential range lower than 0.5 V versus RHE, the ORR appears to proceed via a four-electron mechanism based on the analysis of rotating disc electrode results. A redetermination of the structures of the binary molybdenum nitrides was carried out using neutron diffraction data, which is far more sensitive to nitrogen site positions than X-ray diffraction data. In conclusion, the revised monometallic hexagonal nitride structures all share many common features with the Co 0.6Mo 1.4N 2 structure, which has alternating layers of cations in octahedral and trigonal prismatic coordination, and are thus not limited to only trigonal prismatic Mo environments (as was originally postulated for δ-MoN).« less

48 CFR 252.225-7008 - Restriction on Acquisition of Specialty Metals.

Code of Federal Regulations, 2012 CFR

2012-10-01

... atomization or sputtering of titanium, or final consolidation of non-melt derived titanium powder or titanium alloy powder. (3) Specialty metal means— (i) Steel— (A) With a maximum alloy content exceeding one or..., molybdenum, nickel, niobium (columbium), titanium, tungsten, or vanadium; (ii) Metal alloys consisting of— (A...

48 CFR 252.225-7008 - Restriction on Acquisition of Specialty Metals.

Code of Federal Regulations, 2010 CFR

2010-10-01

... atomization or sputtering of titanium, or final consolidation of non-melt derived titanium powder or titanium alloy powder. (3) Specialty metal means— (i) Steel— (A) With a maximum alloy content exceeding one or..., molybdenum, nickel, niobium (columbium), titanium, tungsten, or vanadium; (ii) Metal alloys consisting of— (A...

48 CFR 252.225-7008 - Restriction on Acquisition of Specialty Metals.

Code of Federal Regulations, 2011 CFR

2011-10-01

... atomization or sputtering of titanium, or final consolidation of non-melt derived titanium powder or titanium alloy powder. (3) Specialty metal means— (i) Steel— (A) With a maximum alloy content exceeding one or..., molybdenum, nickel, niobium (columbium), titanium, tungsten, or vanadium; (ii) Metal alloys consisting of— (A...

Solid-phase zirconium and fluoride species in alkaline zircaloy cladding waste at Hanford.

PubMed

Reynolds, Jacob G; Huber, Heinz J; Cooke, Gary A; Pestovich, John A

2014-08-15

The United States Department of Energy Hanford Site, near Richland, Washington, USA, processed plutonium between 1944 and 1987. Fifty-six million gallons of waste of various origins remain, including waste from removing zircaloy fuel cladding using the so-called Zirflex process. The speciation of zirconium and fluoride in this waste is important because of the corrosivity and reactivity of fluoride as well as the (potentially) high density of Zr-phases. This study evaluates the solid-phase speciation of zirconium and fluoride using X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). Two waste samples were analyzed: one waste sample that is relatively pure zirconium cladding waste from tank 241-AW-105 and another that is a blend of zirconium cladding wastes and other high-level wastes from tank 241-C-104. Villiaumite (NaF) was found to be the dominant fluoride species in the cladding waste and natrophosphate (Na7F[PO4]2 · 19H2O) was the dominant species in the blended waste. Most zirconium was present as a sub-micron amorphous Na-Zr-O phase in the cladding waste and a Na-Al-Zr-O phase in the blended waste. Some zirconium was present in both tanks as either rounded or elongated crystalline needles of Na-bearing ZrO2 that are up to 200 μm in length. These results provide waste process planners the speciation data needed to develop disposal processes for this waste. Copyright © 2014 Elsevier B.V. All rights reserved.

Zirconium-based alloys, nuclear fuel rods and nuclear reactors including such alloys, and related methods

DOEpatents

Mariani, Robert Dominick

2014-09-09

Zirconium-based metal alloy compositions comprise zirconium, a first additive in which the permeability of hydrogen decreases with increasing temperatures at least over a temperature range extending from 350.degree. C. to 750.degree. C., and a second additive having a solubility in zirconium over the temperature range extending from 350.degree. C. to 750.degree. C. At least one of a solubility of the first additive in the second additive over the temperature range extending from 350.degree. C. to 750.degree. C. and a solubility of the second additive in the first additive over the temperature range extending from 350.degree. C. to 750.degree. C. is higher than the solubility of the second additive in zirconium over the temperature range extending from 350.degree. C. to 750.degree. C. Nuclear fuel rods include a cladding material comprising such metal alloy compositions, and nuclear reactors include such fuel rods. Methods are used to fabricate such zirconium-based metal alloy compositions.

The 5-year Results of an Oxidized Zirconium Femoral Component for TKA

PubMed Central

Innocenti, Massimo; Carulli, Christian; Matassi, Fabrizio; Villano, Marco

2009-01-01

Osteolysis secondary to polyethylene wear is one of the major factors limiting long-term performance of TKA. Oxidized zirconium is a new material that combines the strength of a metal with the wear properties of a ceramic. It remains unknown whether implants with a zirconium femoral component can be used safely in TKA. To answer that question, we reviewed, at a minimum of 5 years, the clinical outcome and survivorship of a ceramic-surfaced oxidized zirconium femoral component implanted during 98 primary TKAs between April 2001 and December 2003. Survivorship was 98.7% at 7 years postoperatively. No revision was necessary and only one component failed because of aseptic loosening. Mean Knee Society score improved from 36 to 89. No adverse events were observed clinically or radiologically. These results justify pursuing the use of oxidized zirconium as an alternative bearing surface for a femoral component in TKA. Level of Evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence. PMID:19798541

Breaking America’s Dependence on Foreign…Molybdenum

PubMed Central

Einstein, Andrew J.

2009-01-01

Brief Unstructured Abstract Approximately 9 million nuclear cardiology studies performed each year in the United States employ technetium-99m, which is produced from the decay of molybdenum-99. The fragility of the worldwide technetium-99m supply chain has been underscored by current shortages caused by an unplanned shutdown of Europe’s largest reactor. The majority of the United States’ supply derives from a reactor in Canada nearing the end of its lifespan, whose planned replacements have been recently cancelled. In this article, the clinical importance of technetium-99m and our tenuous dependence on foreign supply of Molybdenum is addressed. PMID:19356583

Tribochemistry of contact interfaces of nanocrystalline molybdenum carbide films

NASA Astrophysics Data System (ADS)

Kumar, D. Dinesh; Kumar, N.; Panda, Kalpataru; Kamalan Kirubaharan, A. M.; Kuppusami, P.

2018-07-01

Transition metal carbides (TMC) are known for their improved tribological properties and are sensitive to the tribo-atmospheric environment. Nanocrystalline molybdenum carbide (MoC) thin films were deposited by DC magnetron sputtering technique using reactive CH4 gas. The friction and wear resistance properties of MoC thin films were significantly improved in humid-atmospheric condition as compared to high-vacuum tribo-condition. A comprehensive chemical analysis of deformed contact interfaces was carried out by X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX) and Raman spectroscopy. XPS and Raman spectroscopy showed the formation of stable molybdenum-oxide (MoO), molybdenum carbide (MoC) and amorphous carbon (a-C) tribo-phases. Moreover, during the sliding in humid-atmospheric condition, these phases were extensively deposited on the sliding steel ball counter body which significantly protected against undesirable friction and wear.

Low-temperature irradiation behavior of uranium-molybdenum alloy dispersion fuel

NASA Astrophysics Data System (ADS)

Meyer, M. K.; Hofman, G. L.; Hayes, S. L.; Clark, C. R.; Wiencek, T. C.; Snelgrove, J. L.; Strain, R. V.; Kim, K.-H.

2002-08-01

Irradiation tests have been conducted to evaluate the performance of a series of high-density uranium-molybdenum (U-Mo) alloy, aluminum matrix dispersion fuels. Fuel plates incorporating alloys with molybdenum content in the range of 4-10 wt% were tested. Two irradiation test vehicles were used to irradiate low-enrichment fuels to approximately 40 and 70 at.% 235U burnup in the advanced test reactor at fuel temperatures of approximately 65 °C. The fuel particles used to fabricate dispersion specimens for most of the test were produced by generating filings from a cast rod. In general, fuels with molybdenum contents of 6 wt% or more showed stable in-reactor fission gas behavior, exhibiting a distribution of small, stable gas bubbles. Fuel particle swelling was moderate and decreased with increasing alloy content. Fuel particles with a molybdenum content of 4 wt% performed poorly, exhibiting extensive fuel-matrix interaction and the growth of relatively large fission gas bubbles. Fuel particles with 4 or 6 wt% molybdenum reacted more rapidly with the aluminum matrix than those with higher-alloy content. Fuel particles produced by an atomization process were also included in the test to determine the effect of fuel particle morphology and microstructure on fuel performance for the U-10Mo composition. Both of the U-10Mo fuel particle types exhibited good irradiation performance, but showed visible differences in fission gas bubble nucleation and growth behavior.

40 CFR 421.220 - Applicability: Description of the secondary molybdenum and vanadium subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING... to discharges resulting from the production of molybdenum or vanadium by secondary molybdenum and...

Magnetoresistance measurements of superconducting molybdenum nitride thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baskaran, R., E-mail: baskaran@igcar.gov.in; Arasu, A. V. Thanikai; Amaladass, E. P.

2016-05-23

Molybdenum nitride thin films have been deposited on aluminum nitride buffered glass substrates by reactive DC sputtering. GIXRD measurements indicate formation of nano-crystalline molybdenum nitride thin films. The transition temperature of MoN thin film is 7.52 K. The transition width is less than 0.1 K. The upper critical field Bc{sub 2}(0), calculated using GLAG theory is 12.52 T. The transition width for 400 µA current increased initially upto 3 T and then decreased, while that for 100 µA current transition width did not decrease.

Synthesis of zirconium oxynitride in air under DC electric fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morisaki, Nobuhiro; Tokunaga, Tomoharu; Sasaki, Katsuhiro

We synthesized zirconium oxynitride from yttria-stabilized zirconia (YSZ) in air by applying DC electric fields that produced a controlled electric current in the specimen. When YSZ was heated under an applied DC electric field, the electric current of the specimen steeply increased at a critical temperature, called a flash event, during flash sintering. By keeping the electric current of the specimen constant during the flash event and then holding the specimen at the critical temperature, YSZ was transformed into zirconium oxynitride under the optimal conditions of 50 V/cm, 500 mA, and 1000 °C. We confirmed that zirconium oxynitride formed using high-resolution transmission electronmore » microscopy, electron energy-loss spectroscopy, and energy-dispersive spectrometry. To convert oxides to nitrides, reducing conditions are necessary to form excess oxygen vacancies. Our technique produced the strong reducing conditions necessary to form nitrides from the oxides by delivering a controlled electric current to the specimen.« less

Accurate X-ray diffraction studies of KTiOPO{sub 4} single crystals doped with niobium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Novikova, N. E., E-mail: natnov@ns.crys.ras.ru; Sorokina, N. I.; Alekseeva, O. A.

2017-01-15

Single crystals of potassium titanyl phosphate doped with 4% of niobium (КТР:4%Nb) and 6% of niobium (KTP:6%Nb) are studied by accurate X-ray diffraction at room temperature. The niobium atoms are localized near the Ti1 and Ti2 atomic positions, and their positions are for the first time refined independent of the titanium atomic positions. Maps of difference electron density in the vicinity of K1 and K2 atomic positions are analyzed. It is found that in the structure of crystal КТР:4%Nb, additional positions of K atoms are located farther from the main positions and from each other than in КТР and KTP:6%Nbmore » crystals. The nonuniform distribution of electron density found in the channels of the КТР:4%Nb structure is responsible for ~20% increase in the signal of second harmonic generation.« less

The oxidation of TaBe sub 12 and NbBe sub 12 coatings on niobium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Courtright, E.L.

1990-01-01

The oxidation behavior of tantalum and niobium beryllide coatings on niobium were evaluated. Intermetallic bond layers consisting of Ir{sub 3}Ta and Ir{sub 3}Nb were used to butter the large thermal expansion mismatch between the beryllide coatings and underlying niobium substrate. All coatings were applied by Triode Sputtering except for a final environmental protection layer of stabilized zirconia deposited by RF Diode using a ceramic target. Severe delamination and spalling occurred during cyclic oxidation exposure, even at temperatures as low as 925{degrees}C, indicating that the bond layer did not prevent the differential expansion stresses from reaching the delamination failure threshold, particularlymore » at the edges and corners. Hot pressed samples of the two beryllide compounds were also exposed to a similar cyclic oxidation history, but, in contrast to the coatings, exhibited excellent oxidation resistance to temperatures as high as 1370{degrees}C. 9 refs., 8 figs., 1 tab.« less

Calcification of MC3T3-E1 cells on titanium and zirconium.

PubMed

Umezawa, Takayuki; Chen, Peng; Tsutsumi, Yusuke; Doi, Hisashi; Ashida, Maki; Suzuki, Shoichi; Moriyama, Keiji; Hanawa, Takao

2015-01-01

To confirm similarity of hard tissue compatibility between titanium and zirconium, calcification of MC3T3-E1 cells on titanium and zirconium was evaluated in this study. Mirror-polished titanium (Ti) and zirconium (Zr) disks and zirconium-sputter deposited titanium (Zr/Ti) were employed in this study. The surface of specimens were characterized using scanning electron microscopy and X-ray diffraction. Then, the cellular proliferation, differentiation and calcification of MC3T3-E1 cells on specimens were investigated. The surface of Zr/Ti was much smoother and cleaner than those of Ti and Zr. The proliferation of the cell was the same among three specimens, while the differentiation and calcification on Zr/Ti were faster than those on Ti and Zr. Therefore, Ti and Zr showed the identical hard tissue compatibility according to the evaluation with MC3T3-E1 cells. Sputter deposition may improve cytocompatibility.

GEMAS: Molybdenum Spatial Distribution Patterns in European Soil

NASA Astrophysics Data System (ADS)

Cicchella, Domenico; Zuzolo, Daniela; Demetriades, Alecos; De Vivo, Benedetto; Eklund, Mikael; Ladenberger, Anna; Negrel, Philippe; O'Connor, Patrick

2017-04-01

Molybdenum is an essential trace element for both plants and animals as well as for human being. It is one such trace element for which potential health concerns have been raised but for which few data exist and little investigation or interpretation of distributions in soils has been made. The main goal of this study was to fill this gap. Molybdenum (Mo) concentrations are reported for the <2 mm fraction of soil samples from agricultural (Ap horizon, 0-20 cm; N=2218) and grazing land (Gr, 0-10 cm; N=2127). The survey covers 33 European countries and 5.6 million km2 at a sample density of 1 site/2500 km2. All samples were analysed by ICP-MS following an aqua regia extraction. The European median Mo concentration is 0.416 mg/kg in agricultural soil and 0.424 mg/kg in grazing land soil. Molybdenum geochemical maps for both land use types (Ap and Gr) show overall similar spatial distribution patterns mainly governed by geology (parent material and mineralisation), as well as weathering, soil formation and climate since the last glaciations period. The dominant feature is represented by low Mo concentrations over the coarse-grained sandy deposits of the last glaciations in central northern Europe while the most extensive anomalies occur in Scandinavian soils. The highest Mo concentration value occurs to the North of Oslo close to one of the largest porphyry Mo deposit of the World. Some interesting anomalous patterns occur also in Italy in correspondence with alkaline volcanics, in Spain and Greece associated with sulfides mineralizations and in Slovenia and Croatia where are probably related to the long weathering history of karstic residual soils. Anomalous concentrations in some areas of Ireland represent a clear example of how an excess of molybdenum has produced potentially toxic pastures. In fact, these give rise to problems particularly in young cattle when excess molybdenum in the herbage acts as an antagonist, which militates against efficient copper

PROCESS OF RECOVERING ZIRCONIUM VALUES FROM HAFNIUM VALUES BY SOLVENT EXTRACTION WITH AN ALKYL PHOSPHATE

DOEpatents

Peppard, D.F.

1960-02-01

A process of separating hafnium nitrate from zirconium nitrate contained in a nitric acid solution by selectively. extracting the zirconium nitrate with a water-immiscible alkyl phosphate is reported.

Removing Molybdenum with the Microalgae Extracted from the Wastewater in Semiconductor Plants

NASA Astrophysics Data System (ADS)

Chiu, Yi-Chuan

2017-04-01

It has been well recognized that algae biomass can treat highly contaminated water in an effective way. Algae can grows in the natural environment without any care and can be efficiently cultivated. Both of living algae and dry algae biomass have been tested to absorb many kinds of toxic pollutants, because there are multiple functional groups on the algae surface capable of binding molybdenum. Therefore, algae become a good choice for the treatment of molybdenum in contaminated waters. In addition, in Taiwan, semiconductor industry is highly developed in the recent three decades. Subsequently, it is believed that some pollutants, such as molybdenum in this study, have become a threat to the surface water, groundwater and even the whole environment. In the previous studies, molybdenum is a well-known essential nutrient for the algae; therefore, the potential to remove molybdenum with algae from the wastewater is worth to be evaluated. The algae species, Chloroidium saccharophilum, was extracted from the wastewater in semiconductor plants for the study of removing molybdenum. A few sorption experiments have been conducted for evaluating the efficiency of removing molybdenum under different values of pH and molybdenum concentration. The absorption of Chloroidium saccharophilum can reach equilibrium in short times, which are 60 and 120 mins for molybdenum concentrations of 600 and 1200 ppb, respectively. The sorption experiments would accept the duration of 120 mins as the contact time and were performed at pH values of 6, 4 and 2 with different concentrations of molybdenum diluted by deionized water. The experiment data confirms that the isotherm has an excellent agreement on Langmuir adsorption model with the correlation coefficients (r2) of > 0.97. It demonstrates that the adsorption capacity (qmax) has an inverse relationship with pH value, which are 826, 2564 and 4761 mgkg-1 for pH 6, 4 and 2, respectively, while those of net enthalpy of adsorption (KL) are 3

Spectroscopic and Kinetic Properties of the Molybdenum-containing, NAD+-dependent Formate Dehydrogenase from Ralstonia eutropha*

PubMed Central

Niks, Dimitri; Duvvuru, Jayant; Escalona, Miguel; Hille, Russ

2016-01-01

We have examined the rapid reaction kinetics and spectroscopic properties of the molybdenum-containing, NAD+-dependent FdsABG formate dehydrogenase from Ralstonia eutropha. We confirm previous steady-state studies of the enzyme and extend its characterization to a rapid kinetic study of the reductive half-reaction (the reaction of formate with oxidized enzyme). We have also characterized the electron paramagnetic resonance signal of the molybdenum center in its MoV state and demonstrated the direct transfer of the substrate Cα hydrogen to the molybdenum center in the course of the reaction. Varying temperature, microwave power, and level of enzyme reduction, we are able to clearly identify the electron paramagnetic resonance signals for four of the iron/sulfur clusters of the enzyme and find suggestive evidence for two others; we observe a magnetic interaction between the molybdenum center and one of the iron/sulfur centers, permitting assignment of this signal to a specific iron/sulfur cluster in the enzyme. In light of recent advances in our understanding of the structure of the molybdenum center, we propose a reaction mechanism involving direct hydride transfer from formate to a molybdenum-sulfur group of the molybdenum center. PMID:26553877

Castable nickel aluminide alloys for structural applications

DOEpatents

Liu, Chain T.

1992-01-01

The specification discloses nickel aluminide alloys which include as a component from about 0.5 to about 4 at. % of one or more of the elements selected from the group consisting of molybdenum or niobium to substantially improve the mechanical properties of the alloys in the cast condition.

Structure of a bimetallic strip produced by plasma spraying of a TiAl powder on a niobium sheet

NASA Astrophysics Data System (ADS)

Povarova, K. B.; Antonova, A. V.; Burmistrov, V. I.; Safronov, B. V.; Perfilov, L. S.; Chukanov, A. P.

2007-10-01

Ti-48 at % Al alloy granules produced by centrifugal spraying are milled into a powder with a particle size of 40 100 μm, and are applied onto a niobium foil using plasma spraying in an argon atmosphere. The fabricated TiAl/Nb bimetallic strip consists of a 100-μm-thick niobium layer and a porous 300-to 400-μm-thick TiAl layer formed by flattened particles. Directly after the preparation of the bimetallic strip, the surface of the TiAl porous layer is rough. Vacuum annealing at 1000, 1100, and 1200°C for 0.5 1.5 h leads to intense pore healing. After deposition and annealing, the interlayer adhesion is strong. The preparation of TiAl granules and spraying of the powder is accompanied by aluminum depletion of the Ti-48 at % Al alloy to 42 45 at % and an increase in the fraction of the α2-Ti3Al phase in the deposited layer. The prepared material has a duplex structure. An intermediate diffuse layer characterized by a variable composition and thickness is formed at the interface. This layer consists of two solid solutions; one of them, which is formed at the TiAl layer, is an α2-Ti3Al-based solid solution of niobium and the other, which is formed at the niobium foil, is a niobium-based solid solution of titanium and aluminum.

Microstructures and Hardness/Wear Performance of High-Carbon Stellite Alloys Containing Molybdenum

NASA Astrophysics Data System (ADS)

Liu, Rong; Yao, J. H.; Zhang, Q. L.; Yao, M. X.; Collier, Rachel

2015-12-01

Conventional high-carbon Stellite alloys contain a certain amount of tungsten which mainly serves to provide strengthening to the solid solution matrix. These alloys are designed for combating severe wear. High-carbon molybdenum-containing Stellite alloys are newly developed 700 series of Stellite family, with molybdenum replacing tungsten, which are particularly employed in severe wear condition with corrosion also involved. Three high-carbon Stellite alloys, designated as Stellite 706, Stellite 712, and Stellite 720, with different carbon and molybdenum contents, are studied experimentally in this research, focusing on microstructure and phases, hardness, and wear resistance, using SEM/EDX/XRD techniques, a Rockwell hardness tester, and a pin-on-disk tribometer. It is found that both carbon and molybdenum contents influence the microstructures of these alloys significantly. The former determines the volume fraction of carbides in the alloys, and the latter governs the amount of molybdenum-rich carbides precipitated in the alloys. The hardness and wear resistance of these alloys are increased with the carbide volume fraction. However, with the same or similar carbon content, high-carbon CoCrMo Stellite alloys exhibit worse wear resistance than high-carbon CoCrW Stellite alloys.

Structural properties of molybdenum-lead-borate glasses.

PubMed

Rada, M; Rada, S; Pascuta, P; Culea, E

2010-11-01

Glasses and glass ceramics in the system xMoO₃·(100 - x)[3B₂O₃·PbO] with 0 ≤ x ≤ 30 mol% have been prepared from melt quenching method and characterized by means of X-ray diffraction, FTIR, UV-VIS and EPR spectroscopy. We have examined and analyzed the effects of systematic molybdenum ions intercalation on lead-borate glasses and glass ceramics with interesting results. The observations present in these mechanisms show the lead ions bonded ionic have a strong affinity towards [BO₃] units containing non-bridging oxygens and [MoO₄]²⁻ molybdate units. The pronounced affinity towards molybdate anions yields the formation of the PbMoO₄ crystalline phase. Then, the excess of oxygen can be supported into the glass network by the formation of [MoO₆] and [Mo₂O₇] structural units. Pb²(+) ions with 6s² configuration show strong absorption in the ultraviolet due to parity allowed s²-sp transition and yield an absorption band centered at about 310 nm. The changes in the features of the absorption bands centered at about 310 nm can be explained as a consequence of the appearance of additional absorption shoulder due to photoinduced color centers in the glass such as the formation of borate-molybdate and lead-molybdate paramagnetic defect centers in the glasses. The concentration of molybdenum ions influences the shape and width of the EPR signals located at g ∼ 1.86, 1.91 and 5.19. The microenvironment of molybdenum ions in glasses is expected to have mainly sixfold coordination. However, there is a possibility of reduction of a part of molybdenum ions from the Mo⁶(+) to the Mo⁵(+) and Mo⁴(+) to the Mo³(+) states. Copyright © 2010 Elsevier B.V. All rights reserved.

Two temperature approach to femtosecond laser oxidation of molybdenum and morphological study

NASA Astrophysics Data System (ADS)

Kotsedi, L.; Kaviyarasu, K.; Fuku, X. G.; Eaton, S. M.; Amara, E. H.; Bireche, F.; Ramponi, R.; Maaza, M.

2017-11-01

The two-temperature model was used to gain insight into the thermal evolution of the hot electrons and the crystal lattice of the molybdenum thin coating during femtosecond laser treatment. The heat from the laser raised the bulk temperature of the sample through heat transfer from the hot electron to the crystal lattice of the material, which then led to the melting of the top layer of the film. This process resulted in the hot melt reacting ambient oxygen, which in turn oxidized the surface of molybdenum coating. The topological study and morphology of the oxidized film was conducted using high-resolution scanning electron microscope, with micrographs taken in both the cross-sectional geometry and normal incidence to the electron beam. The molybdenum oxide nanorods were clearly observed and the x-ray diffraction patterns showed the diffraction peaks due to molybdenum oxide.

Synthesis and Characterization of Molybdenum Based Colloidal Particles.

PubMed

Moreno; Vidoni; Ovalles; Chaudret; Urbina; Krentzein

1998-11-15

The synthesis and characterization of molybdenum colloidal particles were evaluated using thermal and sonochemical methods and starting from different metal precursors, Mo(CO)6 and (NH4)2MoS4. The products were characterized by elemental analysis, spectroscopic (UV, FTIR), and surface analysis (XPS) techniques, as well as by transmission electron microscopy (TEM) for determining the particle sizes. Using Mo(CO)6 as metal source, particle sizes with an average diameter of 1.5 nm can be obtained using tert-amyl alcohol as solvent and tetrahydrothiophene as sulfurating ligand. The characterization of these particles showed that they are composed of molybdenum oxide MoO3. Using (NH4)2MoS4 as metal precursor, particles with average diameters of 4.7 and 2.5 nm were synthesized using thermal and sonochemical methods, respectively. The characterization of these particles showed them to be composed of molybdenum sulfide, MoS2. The sonochemical method proved to be the fastest and most convenient synthetic pathway of obtaining small colloidal particles at low temperatures and with control of the average size. Copyright 1998 Academic Press.

Analysis of the influence of the macro- and microstructure of dental zirconium implants on osseointegration: a minipig study.

PubMed

Mueller, Cornelia Katharina; Solcher, Philipp; Peisker, Andrè; Mtsariashvilli, Maia; Schlegel, Karl Andreas; Hildebrand, Gerhard; Rost, Juergen; Liefeith, Klaus; Chen, Jiang; Schultze-Mosgau, Stefan

2013-07-01

It was the aim of this study to analyze the influence of implant design and surface topography on the osseointegration of dental zirconium implants. Six different implant designs were tested in the study. Nine or 10 test implants were inserted in the frontal skull in each of 10 miniature pigs. Biopsies were harvested after 2 and 4 months and subjected to microradiography. No significant differences between titanium and zirconium were found regarding the microradiographically detected bone-implant contact (BIC). Cylindric zirconium implants showed a higher BIC at the 2-month follow-up than conic zirconium implants. Among zirconium implants, those with an intermediate Ra value showed a significantly higher BIC compared with low and high Ra implants 4 months after surgery. Regarding osseointegration, titanium and zirconium showed equal properties. Cylindric implant design and intermediate surface roughness seemed to enhance osseointegration. Copyright © 2013 Elsevier Inc. All rights reserved.

Frequency optimization in the eddy current test for high purity niobium

NASA Astrophysics Data System (ADS)

Joung, Mijoung; Jung, Yoochul; Kim, Hyungjin

2017-01-01

The eddy current test (ECT) is frequently used as a non-destructive method to check for the defects of high purity niobium (RRR300, Residual Resistivity Ratio) in a superconducting radio frequency (SRF) cavity. Determining an optimal frequency corresponding to specific material properties and probe specification is a very important step. The ECT experiments for high purity Nb were performed to determine the optimal frequency using the standard sample of high purity Nb having artificial defects. The target depth was considered with the treatment step that the niobium receives as the SRF cavity material. The results were analysed via the selectivity that led to a specific result, depending on the size of the defects. According to the results, the optimal frequency was determined to be 200 kHz, and a few features of the ECT for the high purity Nb were observed.

Effect of low temperature baking on the RF properties of niobium superconducting cavities for particle accelerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gianluigi Ciovati

Radio-frequency superconducting (SRF) cavities are widely used to accelerate a charged particle beam in particle accelerators. The performance of SRF cavities made of bulk niobium has significantly improved over the last ten years and is approaching the theoretical limit for niobium. Nevertheless, RF tests of niobium cavities are still showing some ''anomalous'' losses that require a better understanding in order to reliably obtain better performance. These losses are characterized by a marked dependence of the surface resistance on the surface electromagnetic field and can be detected by measuring the quality factor of the resonator as a function of the peakmore » surface field. A low temperature (100 C-150 C) ''in situ'' bake under ultra-high vacuum has been successfully applied as final preparation of niobium RF cavities by several laboratories over the last few years. The benefits reported consist mainly of an improvement of the cavity quality factor at low field and a recovery from ''anomalous'' losses (so-called ''Q-drop'') without field emission at higher field. A series of experiments with a CEBAF single-cell cavity have been carried out at Jefferson Lab to carefully investigate the effect of baking at progressively higher temperatures for a fixed time on all the relevant material parameters. Measurements of the cavity quality factor in the temperature range 1.37 K-280 K and resonant frequency shift between 6 K-9.3 K provide information about the surface resistance, energy gap, penetration depth and mean free path. The experimental data have been analyzed with the complete BCS theory of superconductivity. The hydrogen content of small niobium samples inserted in the cavity during its surface preparation was analyzed with Nuclear Reaction Analysis (NRA). The single-cell cavity has been tested at three different temperatures before and after baking to gain some insight on thermal conductivity and Kapitza resistance and the data are compared with different

Role of electron concentration in softening and hardening of ternary molybdenum alloys

NASA Technical Reports Server (NTRS)

Stephens, J. R.; Witzke, W. R.

1975-01-01

Effects of various combinations of hafnium, tantalum, rhenium, osmium, iridium, and platinum in ternary molybdenum alloys on alloy softening and hardening were determined. Hardness tests were conducted at four test temperatures over the temperature range 77 to 411 K. Results showed that hardness data for ternary molybdenum alloys could be correlated with anticipated results from binary data based upon expressions involving the number of s and d electrons contributed by the solute elements. The correlation indicated that electron concentration plays a dominant role in controlling the hardness of ternary molybdenum alloys.

TERNARY ALLOYS OF URANIUM, COLUMBIUM, AND ZIRCONIUM

DOEpatents

Foote, F.G.

1960-08-01

Ternary alloys of uranium are described which are useful as neutron- reflecting materials in a fast neutron reactor. They are especially resistant to corrosion caused by oxidative processes of gascous or aqueous origin and comprise uranium as the predominant metal with zirconiunn and niobium wherein the total content of the minor alloying elements is between 2 and 8% by weight.

ZIRCONIUM PHOSPHATE ADSORPTION METHOD

DOEpatents

Russell, E.R.; Adamson, A.S.; Schubert, J.; Boyd, G.E.

1958-11-01

A method is presented for separating plutonium values from fission product values in aqueous acidic solution. This is accomplished by flowing the solutlon containing such values through a bed of zirconium orthophosphate. Any fission products adsorbed can subsequently be eluted by washing the column with a solution of 2N HNO/sub 3/ and O.lN H/sub 3/PO/sub 4/. Plutonium values may subsequently be desorbed by contacting the column with a solution of 7N HNO/sub 3/ .

Enhancements to High Temperature In-Pile Thermocouple Performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

J.C. Crepeau; J.L. Rempe; J.E. Daw

2008-03-31

A joint University of Idaho (UI) and Idaho National Laboratory (INL) University Nuclear Research Initiative (UNERI) was to initiated to extend initial INL efforts to develop doped molybdenum/niobium alloy High Temperature Irradiation Resistant Thermocouples (HTIR-TCs). The overall objective of this UNERI was to develop recommendations for an optimized thermocouple design for high temperature, long duration, in-pile testing by expanding upon results from initial INL efforts. Tasks to quantify the impact of candidate enhancements, such as alternate alloys, alternate geometries, and alternate thermocouple fabrication techniques, on thermocouple performance were completed at INL's High Temperature Test Laboratory (HTTL), a state of themore » art facility equipped with specialized equipment and trained staff in the area of high temperature instrumentation development and evaluation. Key results of these evaluations, which are documented in this report, are as follows. The doped molybdenum and Nb-1%Zr, which were proposed in the initial INL HTIR-TC design, were found to retain ductility better than the developmental molybdenum-low niobium alloys and the niobium-low molybdenum alloys evaluated. Hence, the performance and lower cost of the commercially available KW-Mo makes a thermocouple containing KW-Mo and Nb-1%Zr the best option at this time. HTIR-TCs containing larger diameter wires offer the potential to increase HTIR-TC stability and reliability at higher temperatures. HTIR-TC heat treatment temperatures and times should be limited to not more than 100 C above the proposed operating temperatures and to durations of at least 4 to 5 hours. Preliminary investigations suggest that the performance of swaged and loose assembly HTIR-TC designs is similar. However, the swaged designs are less expensive and easier to construct. In addition to optimizing HTIR-TC performance, This UNERI project provided unique opportunities to several University of Idaho students, allowing

Relationship of uranium and other trace elements to post-Cretaceous vulcanism

USGS Publications Warehouse

Coats, Robert R.

1955-01-01

A regional study of the distribution of uranium, boron, tin, beryllium, niobium, lanthanum, lead, zirconium, lithium, and fluorine in 112 samples of Cenozoic volcanic rocks of predominately rhyolitic and dacitic composition has shown that the content of uranium has a significantly high positive correlation with that of niobium, beryllium, and fluorine, a lower but still significant positive correlation with lithium and tin, a significant negative correlation with boron and lanthanum, and no significant correlation with zirconium and lead. A study of the relation of content of the several elements to the geographic provenance shows significant variation with provenance for all these elements, except tin and lanthanum. On the basis of these variations and on patterns of consistency, five comagmatic provinces, one of which is divided into three sub-provinces, have been delimited, in part, on a map of the western United States. The patter of distribution of boron is significantly different from that of the other elements. The regional difference are perhaps best explained by structural control of the effectiveness of vertical transport.

Modeled Neutron and Charged-Particle Induced Nuclear Reaction Cross Sections for Radiochemistry in the Region of Yttrium, Zirconium, Niobium, and Molybdenum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoffman, R D; Kelley, K; Dietrich, F S

2006-06-13

We have developed a set of modeled nuclear reaction cross sections for use in radiochemical diagnostics. Systematics for the input parameters required by the Hauser-Feshbach statistical model were developed and used to calculate neutron, proton, and deuteron induced nuclear reaction cross sections for targets ranging from strontium (Z = 38) to rhodium (Z = 45).

Criticality experiments and analysis of molybdenum reflected cylindrical uranyl fluoride water solution reactors

NASA Technical Reports Server (NTRS)

Fieno, D.; Fox, T.; Mueller, R.

1972-01-01

Clean criticality data were obtained from molybdenum-reflected cylindrical uranyl-fluoride-water solution reactors. Using ENDF/B molybdenum cross sections, a nine energy group two-dimensional transport calculation of a reflected reactor configuration predicted criticality to within 7 cents of the experimental value. For these reactors, it was necessary to compute the reflector resonance integral by a detailed transport calculation at the core-reflector interface volume in the energy region of the two dominant resonances of natural molybdenum.

Mapping the formation areas of giant molybdenum blue clusters: a spectroscopic study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Botar, Bogdan; Ellern, Arkady; Kogerler, Paul

2012-05-18

The self-assembly of soluble molybdenum blue species from simple molybdate solutions has primarily been associated with giant mixed-valent wheel-shaped cluster anions, derived from the {MoV/VI154/176} archetypes, and a {MoV/VI368} lemon-shaped cluster. The combined use of Raman spectroscopy and kinetic precipitation as self-assembly monitoring techniques and single-crystal X-ray diffraction is key to mapping the realm of molybdenum blue species by establishing spherical {MoV/VI102}-type Keplerates as an important giant molybdenum blue-type species. We additionally rationalize the empirical effect of reducing agent concentration on the formation of all three relevant skeletal types: wheel, lemon and spheres. Whereas both wheels and the lemon-shaped {MoV/VI368}more » cluster are obtained from weakly reduced molybdenum blue solutions, considerably higher reduced solutions lead to {MoV/VI102}-type Keplerates.« less

PRECIPITATION OF ZIRCONIUM AND FLUORIDE IONS FROM SOLUTIONS

DOEpatents

Newby, B.J.

1963-06-11

A process is given for removing zirconium and fluorine ions from aqueous solutions also containing uranium(VI). The precipitation is carried out with sodium formate, and the uranium remains in solution. (AEC)

Molybdenum chloride catalysts for Z-selective olefin metathesis reactions

NASA Astrophysics Data System (ADS)

Koh, Ming Joo; Nguyen, Thach T.; Lam, Jonathan K.; Torker, Sebastian; Hyvl, Jakub; Schrock, Richard R.; Hoveyda, Amir H.

2017-01-01

The development of catalyst-controlled stereoselective olefin metathesis processes has been a pivotal recent advance in chemistry. The incorporation of appropriate ligands within complexes based on molybdenum, tungsten and ruthenium has led to reactivity and selectivity levels that were previously inaccessible. Here we show that molybdenum monoaryloxide chloride complexes furnish higher-energy (Z) isomers of trifluoromethyl-substituted alkenes through cross-metathesis reactions with the commercially available, inexpensive and typically inert Z-1,1,1,4,4,4-hexafluoro-2-butene. Furthermore, otherwise inefficient and non-stereoselective transformations with Z-1,2-dichloroethene and 1,2-dibromoethene can be effected with substantially improved efficiency and Z selectivity. The use of such molybdenum monoaryloxide chloride complexes enables the synthesis of representative biologically active molecules and trifluoromethyl analogues of medicinally relevant compounds. The origins of the activity and selectivity levels observed, which contradict previously proposed principles, are elucidated with the aid of density functional theory calculations.

Molybdenum L-Edge XAS Spectra of MoFe Nitrogenase

PubMed Central

Bjornsson, Ragnar; Delgado-Jaime, Mario U; Lima, Frederico A; Sippel, Daniel; Schlesier, Julia; Weyhermüller, Thomas; Einsle, Oliver; Neese, Frank; DeBeer, Serena

2015-01-01

A molybdenum L-edge X-ray absorption spectroscopy (XAS) study is presented for native and oxidized MoFe protein of nitrogenase as well as Mo-Fe model compounds. Recently collected data on MoFe protein (in oxidized and reduced forms) is compared to previously published Mo XAS data on the isolated FeMo cofactor in NMF solution and put in context of the recent Mo K-edge XAS study, which showed a MoIII assignment for the molybdenum atom in FeMoco. The L3-edge data are interpreted within a simple ligand-field model, from which a time-dependent density functional theory (TDDFT) approach is proposed as a way to provide further insights into the analysis of the molybdenum L3-edges. The calculated results reproduce well the relative spectral trends that are observed experimentally. Ultimately, these results give further support for the MoIII assignment in protein-bound FeMoco, as well as isolated FeMoco. PMID:26213424

Reactivity of zirconium basic sulfate in the reactions with carbonate, oxalate, and phosphate reagents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nekhamkin, L.G.; Kondrashova, I.A.; Kerina, V.R.

1987-08-20

The reactivity of zirconium basic sulfate is determined by the possibility of replacement of oxo- and hydroxo-ligands and decreases with increasing temperature of its precipitation. The interaction of the less reactive zirconium basic sulfate with carbonate and oxalate reagents occurs at 25/sup 0/C without any change in basicity and that with phosphate reagents occurs with a decrease in it, up to the formation of a monophosphate with basicity about 20%. In the interaction of the more reactive zirconium basic sulfate, obtained without heating, oxo- and hydroxo groups can be entirely replaced by acido-ligands with the formation of unhydrolyzed compounds.

Mineral resources potential map of the Lost Cove and Harper Creek Roadless Areas, Avery and Caldwell counties, North Carolina

USGS Publications Warehouse

Crandall, T.M.; Ross, R.B.; Whitlow, J.W.; Griffitts, W.R.

1982-01-01

Mineral resources having low to moderate potential are gold and minerals of thorium, beryllium, niobium, and copper. Stone has a low economic potential; lead, molybdenum, and titanium have low resource potential. These conclusions are based on results of prospect examination, radiometric survey, geochemical survey of stream sediments, saprolite, and bedrock.

Spectroellipsometric detection of silicon substrate damage caused by radiofrequency sputtering of niobium oxide

NASA Astrophysics Data System (ADS)

Lohner, Tivadar; Serényi, Miklós; Szilágyi, Edit; Zolnai, Zsolt; Czigány, Zsolt; Khánh, Nguyen Quoc; Petrik, Péter; Fried, Miklós

2017-11-01

Substrate surface damage induced by deposition of metal atoms by radiofrequency (rf) sputtering or ion beam sputtering onto single-crystalline silicon (c-Si) surface has been characterized earlier by electrical measurements. The question arises whether it is possible to characterize surface damage using spectroscopic ellipsometry (SE). In our experiments niobium oxide layers were deposited by rf sputtering on c-Si substrates in gas mixture of oxygen and argon. Multiple angle of incidence spectroscopic ellipsometry measurements were performed, a four-layer optical model (surface roughness layer, niobium oxide layer, native silicon oxide layer and ion implantation-amorphized silicon [i-a-Si] layer on a c-Si substrate) was created in order to evaluate the spectra. The evaluations yielded thicknesses of several nm for the i-a-Si layer. Better agreement could be achieved between the measured and the generated spectra by inserting a mixed layer (with components of c-Si and i-a-Si applying the effective medium approximation) between the silicon oxide layer and the c-Si substrate. High depth resolution Rutherford backscattering (RBS) measurements were performed to investigate the interface disorder between the deposited niobium oxide layer and the c-Si substrate. Atomic resolution cross-sectional transmission electron microscopy investigation was applied to visualize the details of the damaged subsurface region of the substrate.

Preparation of lead-zirconium-titanium film and powder by electrodeposition

DOEpatents

Bhattacharya, Raghu N.; Ginley, David S.

1995-01-01

A process for the preparation of lead-zirconium-titanium (PZT) film and powder compositions. The process comprises the steps of providing an electrodeposition bath, providing soluble salts of lead, zirconium and titanium metals to this bath, electrically energizing the bath to thereby direct ions of each respective metal to a substrate electrode and cause formation of metallic particles as a recoverable film of PZT powder on the electrode, and also recovering the resultant film as a powder. Recovery of the PZT powder can be accomplished by continually energizing the bath to thereby cause powder initially deposited on the substrate-electrode to drop therefrom into the bath from which it is subsequently removed. A second recovery alternative comprises energizing the bath for a period of time sufficient to cause PZT powder deposition on the substrate-electrode only, from which it is subsequently recovered. PZT film and powder so produced can be employed directly in electronic applications, or the film and powder can be subsequently oxidized as by an annealing process to thereby produce lead-zirconium-titanium oxide for use in electronic applications.

Niobium boride layers deposition on the surface AISI D2 steel by a duplex treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kon, O., E-mail: okon42@htotmail.com; Pazarlioglu, S.; Sen, S.

2015-03-30

In this paper, we investigated the possibility of deposition of niobium boride layers on the surface of AISI D2 steel by a duplex treatment. At the first step of duplex treatment, boronizing was performed on AISI D2 steel samples at 1000{sup o}C for 2h and then pre-boronized samples niobized at 850°C, 900°C and 950°C using thermo-reactive deposition method for 1–4 h. The presence of the niobium boride layers such as NbB, NbB{sub 2} and Nb{sub 3}B{sub 4} and also iron boride phases such as FeB, Fe{sub 2}B were examined by X-ray diffraction analysis. Scanning electron microscope (SEM) and micro-hardness measurementsmore » were realized. Experimental studies showed that the depth of the coating layers increased with increasing temperature and times and also ranged from 0.42 µm to 2.43 µm, depending on treatment time and temperature. The hardness of the niobium boride layer was 2620±180 HV{sub 0.005}.« less

Survey of Portions of the Chromium-Cobalt-Nickel-Molybdenum Quaternary System at 1,200 Degrees C

NASA Technical Reports Server (NTRS)

Rideout, Sheldon Paul; Beck, Paul A

1953-01-01

A survey was made of portions of the chromium-cobalt-nickel-molybdenum quaternary system at 1,200 degrees c by means of microscopic and x-ray diffraction studies. Since the face-centered cubic (alpha) solid solutions form the matrix of almost all practically useful high-temperature alloys, the solid solubility limits of the quaternary alpha phase were determined up to 20 percent molybdenum. The component cobalt-nickel-molybdenum, chromium-cobalt-molybdenum, and chromium-nickel-molybdenum ternary systems were also studied. The survey of these systems was confined to the determination of the boundaries of the face-centered cubic (alpha) solid solutions and of the phases coexisting with alpha at 1,200 degrees c.

METHOD AND ALLOY FOR BONDING TO ZIRCONIUM

DOEpatents

McCuaig, F.D.; Misch, R.D.

1960-04-19

A brazing alloy can be used for bonding zirconium and its alloys to other metals, ceramics, and cermets, and consists of 6 to 9 wt.% Ni, 6 to 9 wn~.% Cr, Mo, or W, 0 to 7.5 wt.% Fe, and the balance Zr.

Carbon nanotube synthesis via the catalytic chemical vapor deposition of methane in the presence of iron, molybdenum, and iron-molybdenum alloy thin layer catalysts

NASA Astrophysics Data System (ADS)

Yahyazadeh, Arash; Khoshandam, Behnam

In this study, we documented the catalytic chemical vapor deposition synthesis of carbon nanotubes (CNTs) using ferrocene and molybdenum hexacarbonyl as catalyst nanoparticle precursors and methane as a nontoxic and economical carbon source for the first time. Field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, wavelength dispersive X-ray spectrometry and transmission electron microscopy of the thin layer catalyst as a simple and cost effective catalyst preparation after methane decomposition reaction, along with Fourier transform infrared spectroscopy and Raman spectroscopy confirmed the growth of CNTs, from bimetallic nanoparticles, which are converted into iron-molybdenum alloy nanoparticles at 700 °C for pretreatment by hydrogen after chemical vapor deposition of thin layers. An investigation of the weight percentages of the chemical elements present in the CNTs synthesized from iron-molybdenum catalyst using quartz sheet substrate at 750 °C, confirmed a significant carbon yield of 75.4% which represents high catalyst activity. Additionally, multi-walled carbon nanotubes (∼16-55 nm in diameter and 1.2 μm in length) were observed in the iron-molybdenum alloy sample after methane decomposition reaction at 750 °C for 35 min. To show the role of iron and molybdenum coated on silicon substrate as two thin layer catalysts, samples were considered for CNTs growth (diameter ∼47-69 nm) at 800 °C and 830 °C, respectively. Moreover, the effect of hydrogen pretreatment was evaluated in terms of active metal coating properly. The best graphitic structure due to Raman spectroscopy outcomes (ID/IG ratio) was obtained for iron coated on a quartz sheet, which was estimated at 0.8505. Thermogravimetric analysis proved the thermal stability of the synthesized CNTs using iron thin-layer catalyst up to 350 °C.

Preliminary Experience with ''In-Site'' Baking of Niobium Cavities

DOE Office of Scientific and Technical Information (OSTI.GOV)

P. Kneisel

In a series of experiments several single cell and multi-cell niobium cavities made from reactor grade and high RRR niobium (frequencies were 700 MHz, 1300 MHz and 1497 MHz) have been baked--after initial testing--in-situ around 145 C for up to 90 hours prior to being recooled. Surprisingly, all cavities showed significant improvements in Q-values between 4.2 and 1.6K. The BCS surface resistance was lowered by nearly a factor of two. This cannot be explained by solely a reduction of dielectric losses caused by adsorbates at the surface or by a decrease of the mean free path due to possibly diffusionmore » of oxygen into the surface layer. In several experiments also the high field behavior of the cavity improved after the in-situ baking procedure. The observed effect opens the possibility for the CEBAF upgrade cavities, which in turn will permit to run the cavities at higher gradients if field emission loading can be prevented. Utilizing this effect can possibly translate into sizeable cost savings since fewer modules are needed for the upgrade program.« less

Conducting metal oxide and metal nitride nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

DiSalvo, Jr., Francis J.; Subban, Chinmayee V.

Conducting metal oxide and nitride nanoparticles that can be used in fuel cell applications. The metal oxide nanoparticles are comprised of for example, titanium, niobium, tantalum, tungsten and combinations thereof. The metal nitride nanoparticles are comprised of, for example, titanium, niobium, tantalum, tungsten, zirconium, and combinations thereof. The nanoparticles can be sintered to provide conducting porous agglomerates of the nanoparticles which can be used as a catalyst support in fuel cell applications. Further, platinum nanoparticles, for example, can be deposited on the agglomerates to provide a material that can be used as both an anode and a cathode catalyst supportmore » in a fuel cell.« less

Zirconium amine tris(phenolate): A more effective initiator for biomedical lactide.

PubMed

Jones, Matthew D; Wu, Xujun; Chaudhuri, Julian; Davidson, Matthew G; Ellis, Marianne J

2017-11-01

Here a zirconium amine tris(phenolate) is used as the initiator for the production of polylactide for biomedical applications, as a replacement for a tin initiator (usually tin octanoate). The ring opening polymerization (ROP) was carried out in the melt at 130°C. The zirconium-catalyzed PLA (PLA-Zr) required 30min, resulting in a polydispersity index (PDI) of 1.17, compared to 1h and PDI=1.77 for tin-catalyzed PLA (PLA-Sn). PLA-Zr and PLA-Sn supported osteosarcoma cell (MG63) culture to the same extent (cell number, morphology, extracellular matrix production and osteogenic function) until day 14 when the PLA-Zr showed increased cell number, overall extracellular matrix production and osteogenic function. To conclude, the reduction in reaction time, controllable microstructure and biologically benign nature of the zirconium amine tris(phenolate) initiator shows that it is a more effective initiator for ROP of polylactide for biomedical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Impact resistance performance of diamond film on a curved molybdenum substrate

NASA Astrophysics Data System (ADS)

Chen, Yang; Gou, Li

2017-08-01

Diamond films with different thicknesses were deposited on flat and curved molybdenum substrate by the microwave plasma chemical vapour deposition (MPCVD) method. Scanning electronic microscopy, atomic force microscopy and Raman spectroscopy were employed to characterise the morphology, the surface roughness and the composition of the films, respectively. A NanoTest system was used for hardness, elastic modulus and nanoimpact tests. The curved surface and ductility of the molybdenum substrate allow large deformation for the thinner films. The substrate has less effect on impact for the thicker film, the deformation of which is mainly determined by the film composition. Under a load of 50 mN and 75 cycles, less deformation occurred for the 22 μm thick film on the curved molybdenum substrate.

Dispersion Strengthening of High Temperature Niobium Alloys

DTIC Science & Technology

1988-05-31

Fig. 2 for the alloys containing ZrC and Ta6 Si3 respectively. The former shows classical age .hardening response with hardening followed by softening...tILE COP) ION STRENGTH’ENING OF HIGH TEMATURE NIOBIUM ALLOYS Prepared by D.L. Anton 00 D.B. Snow In) A.F. Giamei ANNUAL REPORT Contract F49620486-C...Center / ni .’ - k- ADDRESS (Ciy, State, and ZIP Code) 7b ADDRESS (City, State, and ZIP Code) East Hartford, CT 06108 7-Jc\\ 4 0 _ .F3 A.C 8a. NAME OF

Niobium thin film coating on a 500-MHz copper cavity by plasma deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haipeng Wang; Genfa Wu; H. Phillips

2005-05-16

A system using an Electron Cyclotron Resonance (ECR) plasma source for the deposition of a thin niobium film inside a copper cavity for superconducting accelerator applications has been designed and is being constructed. The system uses a 500-MHz copper cavity as both substrate and vacuum chamber. The ECR plasma will be created to produce direct niobium ion deposition. The central cylindrical grid is DC biased to control the deposition energy. This paper describes the design of several subcomponents including the vacuum chamber, RF supply, biasing grid and magnet coils. Operational parameters are compared between an operating sample deposition system andmore » this system. Engineering work progress toward the first plasma creation will be reported here.« less

Molybdenum oxide electrodes for thermoelectric generators

DOEpatents

Schmatz, Duane J.

1989-01-01

The invention is directed to a composite article suitable for use in thermoelectric generators. The article comprises a thin film comprising molybdenum oxide as an electrode deposited by physical deposition techniques onto solid electrolyte. The invention is also directed to the method of making same.

Atomic layer deposition of zirconium silicate films using zirconium tetrachloride and tetra-n-butyl orthosilicate

NASA Astrophysics Data System (ADS)

Kim, Won-Kyu; Kang, Sang-Woo; Rhee, Shi-Woo; Lee, Nae-In; Lee, Jong-Ho; Kang, Ho-Kyu

2002-11-01

Atomic layer chemical vapor deposition of zirconium silicate films with a precursor combination of ZrCl4 and tetra-n-butyl orthosilicate (TBOS) was studied for high dielectric gate insulators. The effect of deposition conditions, such as deposition temperature, pulse time for purge and precursor injection on the deposition rate per cycle, and composition of the film were studied. At 400 °C, the growth rate saturated to 1.35 Å/cycle above 500 sccm of the argon purge flow rate. The growth rate, composition ratio ((Zr/Zr+Si)), and impurity contents (carbon and chlorine) saturated with the increase of the injection time of ZrCl4 and TBOS and decreased with the increased deposition temperature from 300 to 500 °C. The growth rate, composition ratio, carbon, and chlorine contents of the Zr silicate thin films deposited at 500 °C were 1.05 Å/cycle, 0.23, 1.1 at. %, and 2.1 at. %, respectively. It appeared that by using only zirconium chloride and silicon alkoxide sources, the content of carbon and chlorine impurities could not be lowered below 1%. It was also found that the incorporation rate of metal from halide source was lower than alkoxide source.

Reactive Melt Infiltration of Silicon-Niobium Alloys in Microporous Carbons

NASA Technical Reports Server (NTRS)

Singh, M.; Behrendt, D. R.

1994-01-01

Studies of the reactive melt infiltration of silicon-niobium alloys in microporous carbon preforms prepared by the pyrolysis of a polymer precursor have been carried out using modeling, Differential Thermal Analysis (DTA), and melt infiltration. Mercury porosimetry results indicate a very narrow pore size distribution with virtually all the porosity within the carbon preforms open to infiltrants. The morphology and amount of the residual phases (niobium disilicide and silicon) in the infiltrated material can be tailored according to requirements by careful control of the properties (pore size and pore volume) of the porous carbon preforms and alloy composition. The average room temperature four-point flexural strength of a reaction-formed silicon carbide material (made by the infiltration of medium pore size carbon preform with Si - 5 at. % Nb alloy) is 290 +/- 40 MPa (42 +/- 6 ksi) and the fracture toughness is 3.7 +/- 0.3 MPa square root of m. The flexural strength decreases at high temperatures due to relaxation of residual thermal stresses and the presence of free silicon in the material.

Thermal flux limited electron Kapitza conductance in copper-niobium multilayers

DOE PAGES

Cheaito, Ramez; Hattar, Khalid Mikhiel; Gaskins, John T.; ...

2015-03-05

The interplay between the contributions of electron thermal flux and interface scattering to the Kapitza conductance across metal-metal interfaces through measurements of thermal conductivity of copper-niobium multilayers was studied. Thermal conductivities of copper-niobium multilayer films of period thicknesses ranging from 5.4 to 96.2 nm and sample thicknesses ranging from 962 to 2677 nm are measured by time-domain thermoreflectance over a range of temperatures from 78 to 500 K. The Kapitza conductances between the Cu and Nb interfaces in multilayer films are determined from the thermal conductivities using a series resistor model and are in good agreement with the electron diffusemore » mismatch model. The results for the thermal boundary conductance between Cu and Nb are compared to literature values for the thermal boundary conductance across Al-Cu and Pd-Ir interfaces, and demonstrate that the interface conductance in metallic systems is dictated by the temperature derivative of the electron energy flux in the metallic layers, rather than electron mean free path or scattering processes at the interface.« less

Human biokinetic data and a new compartmental model of zirconium--a tracer study with enriched stable isotopes.

PubMed

Greiter, Matthias B; Giussani, Augusto; Höllriegl, Vera; Li, Wei Bo; Oeh, Uwe

2011-09-01

Biokinetic models describing the uptake, distribution and excretion of trace elements are an essential tool in nutrition, toxicology, or internal dosimetry of radionuclides. Zirconium, especially its radioisotope (95)Zr, is relevant to radiation protection due to its production in uranium fission and neutron activation of nuclear fuel cladding material. We present a comprehensive set of human data from a tracer study with stable isotopes of zirconium. The data are used to refine a biokinetic model of zirconium. Six female and seven male healthy adult volunteers participated in the study. It includes 16 complete double tracer investigations with oral ingestion and intravenous injection, and seven supplemental investigations. Tracer concentrations were measured in blood plasma and urine collected up to 100 d after tracer administration. The four data sets (two chemical tracer forms in plasma and urine) each encompass 105-240 measured concentration values above detection limits. Total fractional absorption of ingested zirconium was found to be 0.001 for zirconium in citrate-buffered drinking solution and 0.007 for zirconium oxalate solution. Biokinetic models were developed based on the linear first-order kinetic compartmental model approach used by the International Commission on Radiological Protection (ICRP). The main differences of the optimized systemic model of zirconium to the current ICRP model are (1) recycling into the transfer compartment made necessary by the observed tracer clearance from plasma, (2) different parameters related to fractional absorption for each form of the ingested tracer, and (3) a physiologically based excretion pathway to urine. The study considerably expands the knowledge on the biokinetics of zirconium, which was until now dominated by data from animal studies. The proposed systemic model improves the existing ICRP model, yet is based on the same principles and fits well into the ICRP radiation protection approach. Copyright © 2011

Molybdenum-copper and tungsten-copper alloys and method of making

DOEpatents

Schmidt, Frederick A.; Verhoeven, John D.; Gibson, Edwin D.

1989-05-23

Molybdenum-copper and tungsten-copper alloys are prepared by a consumable electrode method in which the electrode consists of a copper matrix with embedded strips of refractory molybdenum or tungsten. The electrode is progressively melted at its lower end with a superatmospheric inert gas pressure maintained around the liquifying electrode. The inert gas pressure is sufficiently above the vapor pressure of copper at the liquidus temperature of the alloy being formed to suppress boiling of liquid copper.

Molybdenum-copper and tungsten-copper alloys and method of making

DOEpatents

Schmidt, F.A.; Verhoeven, J.D.; Gibson, E.D.

1989-05-23

Molybdenum-copper and tungsten-copper alloys are prepared by a consumable electrode method in which the electrode consists of a copper matrix with embedded strips of refractory molybdenum or tungsten. The electrode is progressively melted at its lower end with a superatmospheric inert gas pressure maintained around the liquefying electrode. The inert gas pressure is sufficiently above the vapor pressure of copper at the liquidus temperature of the alloy being formed to suppress boiling of liquid copper. 6 figs.

Improved the microstructures and properties of M3:2 high-speed steel by spray forming and niobium alloying

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, L.; Hou, L.G., E-mail: lghou@skl.ustb.edu.cn; Zhang, J.X.

The microstructures and properties of spray formed (SF) high-speed steels (HSSs) with or without niobium (Nb) addition were studied. Particular emphasis was placed on the effect of Nb on the solidification microstructures, decomposition of M{sub 2}C carbides, thermal stability and mechanical properties. The results show that spray forming can refine the cell size of eutectic carbides due to the rapid cooling effect during atomization. With Nb addition, further refinement of the eutectic carbides and primary austenite grains are obtained. Moreover, the Nb addition can accelerate the decomposition of M{sub 2}C carbides and increase the thermal stability of high-speed steel, andmore » also can improve the hardness and bending strength with slightly decrease the impact toughness. The high-speed steel made by spray forming and Nb alloying can give a better tool performance compared with powder metallurgy M3:2 and commercial AISI M2 high-speed steels. - Highlights: • Spray forming can effectively refine the microstructure of M3:2 steel. • Niobium accelerates the decomposition of M{sub 2}C carbides. • Niobium increases the hardness and bending strength of spray formed M3:2 steel. • Spray-formed niobium-containing M3:2 steel has the best tool performance.« less

Solid-state NMR/NQR and first-principles study of two niobium halide cluster compounds.

PubMed

Perić, Berislav; Gautier, Régis; Pickard, Chris J; Bosiočić, Marko; Grbić, Mihael S; Požek, Miroslav

2014-01-01

Two hexanuclear niobium halide cluster compounds with a [Nb6X12](2+) (X=Cl, Br) diamagnetic cluster core, have been studied by a combination of experimental solid-state NMR/NQR techniques and PAW/GIPAW calculations. For niobium sites the NMR parameters were determined by using variable Bo field static broadband NMR measurements and additional NQR measurements. It was found that they possess large positive chemical shifts, contrary to majority of niobium compounds studied so far by solid-state NMR, but in accordance with chemical shifts of (95)Mo nuclei in structurally related compounds containing [Mo6Br8](4+) cluster cores. Experimentally determined δiso((93)Nb) values are in the range from 2,400 to 3,000 ppm. A detailed analysis of geometrical relations between computed electric field gradient (EFG) and chemical shift (CS) tensors with respect to structural features of cluster units was carried out. These tensors on niobium sites are almost axially symmetric with parallel orientation of the largest EFG and the smallest CS principal axes (Vzz and δ33) coinciding with the molecular four-fold axis of the [Nb6X12](2+) unit. Bridging halogen sites are characterized by large asymmetry of EFG and CS tensors, the largest EFG principal axis (Vzz) is perpendicular to the X-Nb bonds, while intermediate EFG principal axis (Vyy) and the largest CS principal axis (δ11) are oriented in the radial direction with respect to the center of the cluster unit. For more symmetrical bromide compound the PAW predictions for EFG parameters are in better correspondence with the NMR/NQR measurements than in the less symmetrical chlorine compound. Theoretically predicted NMR parameters of bridging halogen sites were checked by (79/81)Br NQR and (35)Cl solid-state NMR measurements. Copyright © 2014 Elsevier Inc. All rights reserved.

Deformation-induced structural transition in body-centred cubic molybdenum

PubMed Central

Wang, S. J.; Wang, H.; Du, K.; Zhang, W.; Sui, M. L.; Mao, S. X.

2014-01-01

Molybdenum is a refractory metal that is stable in a body-centred cubic structure at all temperatures before melting. Plastic deformation via structural transitions has never been reported for pure molybdenum, while transformation coupled with plasticity is well known for many alloys and ceramics. Here we demonstrate a structural transformation accompanied by shear deformation from an original <001>-oriented body-centred cubic structure to a <110>-oriented face-centred cubic lattice, captured at crack tips during the straining of molybdenum inside a transmission electron microscope at room temperature. The face-centred cubic domains then revert into <111>-oriented body-centred cubic domains, equivalent to a lattice rotation of 54.7°, and ~15.4% tensile strain is reached. The face-centred cubic structure appears to be a well-defined metastable state, as evidenced by scanning transmission electron microscopy and nanodiffraction, the Nishiyama–Wassermann and Kurdjumov–Sachs relationships between the face-centred cubic and body-centred cubic structures and molecular dynamics simulations. Our findings reveal a deformation mechanism for elemental metals under high-stress deformation conditions. PMID:24603655

Process for massively hydriding zirconium--uranium fuel elements

DOEpatents

Katz, N.H.

1973-12-01

A method is described of hydriding uranium-zirconium alloy by heating the alloy in a vacuum, introducing hydrogen and maintaining an elevated temperature until occurrence of the beta--delta phase transformation and isobarically cooling the composition. (Official Gazette)

Crystallography and Morphology of MC Carbides in Niobium-Titanium Modified As-Cast HP Alloys

NASA Astrophysics Data System (ADS)

Buchanan, Karl G.; Kral, Milo V.; Bishop, Catherine M.

2014-07-01

The microstructures of two as-cast heats of HP alloy stainless steels modified with niobium and titanium were examined with particular attention paid to the interdendritic niobium-titanium-rich carbides formed during solidification of these alloys. Generally, these precipitates obtain a blocky morphology in the as-cast condition. However, the (NbTi)C precipitates may obtain a nodular morphology. To provide further insight to the origin of the two different morphologies obtained by the (NbTi)C precipitates in the HP-NbTi alloy, the microstructure and crystallography of each have been studied in detail using scanning electron microscopy, transmission electron microscopy, various electron diffraction methods (EBSD, SAD, and CBED), and energy-dispersive X-ray spectroscopy.

Zirconium-modified materials for selective adsorption and removal of aqueous arsenic

DOEpatents

Zhao, Hongting; Moore, Robert C.

2004-11-30

A method, composition, and apparatus for removing contaminant species from an aqueous medium comprising: providing a material to which zirconium has been added, the material selected from one or more of zeolites, cation-exchangeable clay minerals, fly ash, mesostructured materials, activated carbons, cellulose acetate, and like porous and/or fibrous materials; and contacting the aqueous medium with the material to which zirconium has been added. The invention operates on all arsenic species in the form of arsenate, arsenite and organometallic arsenic, with no pretreatment necessary (e.g., oxidative conversion of arsenite to arsenate).

Interface confined hydrogen evolution reaction in zero valent metal nanoparticles-intercalated molybdenum disulfide

PubMed Central

Chen, Zhongxin; Leng, Kai; Zhao, Xiaoxu; Malkhandi, Souradip; Tang, Wei; Tian, Bingbing; Dong, Lei; Zheng, Lirong; Lin, Ming; Yeo, Boon Siang; Loh, Kian Ping

2017-01-01

Interface confined reactions, which can modulate the bonding of reactants with catalytic centres and influence the rate of the mass transport from bulk solution, have emerged as a viable strategy for achieving highly stable and selective catalysis. Here we demonstrate that 1T′-enriched lithiated molybdenum disulfide is a highly powerful reducing agent, which can be exploited for the in-situ reduction of metal ions within the inner planes of lithiated molybdenum disulfide to form a zero valent metal-intercalated molybdenum disulfide. The confinement of platinum nanoparticles within the molybdenum disulfide layered structure leads to enhanced hydrogen evolution reaction activity and stability compared to catalysts dispersed on carbon support. In particular, the inner platinum surface is accessible to charged species like proton and metal ions, while blocking poisoning by larger sized pollutants or neutral molecules. This points a way forward for using bulk intercalated compounds for energy related applications. PMID:28230105

Niobium superconducting rf cavity fabrication by electrohydraulic forming

NASA Astrophysics Data System (ADS)

Cantergiani, E.; Atieh, S.; Léaux, F.; Perez Fontenla, A. T.; Prunet, S.; Dufay-Chanat, L.; Koettig, T.; Bertinelli, F.; Capatina, O.; Favre, G.; Gerigk, F.; Jeanson, A. C.; Fuzeau, J.; Avrillaud, G.; Alleman, D.; Bonafe, J.; Marty, P.

2016-11-01

Superconducting rf (SRF) cavities are traditionally fabricated from superconducting material sheets or made of copper coated with superconducting material, followed by trim machining and electron-beam welding. An alternative technique to traditional shaping methods, such as deep-drawing and spinning, is electrohydraulic forming (EHF). In EHF, half-cells are obtained through ultrahigh-speed deformation of blank sheets, using shockwaves induced in water by a pulsed electrical discharge. With respect to traditional methods, such a highly dynamic process can yield interesting results in terms of effectiveness, repeatability, final shape precision, higher formability, and reduced springback. In this paper, the first results of EHF on high purity niobium are presented and discussed. The simulations performed in order to master the multiphysics phenomena of EHF and to adjust its process parameters are presented. The microstructures of niobium half-cells produced by EHF and by spinning have been compared in terms of damage created in the material during the forming operation. The damage was assessed through hardness measurements, residual resistivity ratio (RRR) measurements, and electron backscattered diffraction analyses. It was found that EHF does not worsen the damage of the material during forming and instead, some areas of the half-cell have shown lower damage compared to spinning. Moreover, EHF is particularly advantageous to reduce the forming time, preserve roughness, and to meet the final required shape accuracy.

Joining of alumina via copper/niobium/copper interlayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marks, Robert A.; Chapman, Daniel R.; Danielson, David T.

2000-03-15

Alumina has been joined at 1150 degrees C and 1400 degrees C using multilayer copper/niobium/copper interlayers. Four-point bend strengths are sensitive to processing temperature, bonding pressure, and furnace environment (ambient oxygen partial pressure). Under optimum conditions, joints with reproducibly high room temperature strengths (approximately equal 240 plus/minus 20 MPa) can be produced; most failures occur within the ceramic. Joints made with sapphire show that during bonding an initially continuous copper film undergoes a morphological instability, resulting in the formation of isolated copper-rich droplets/particles at the sapphire/interlayer interface, and extensive regions of direct bonding between sapphire and niobium. For optimized aluminamore » bonds, bend tests at 800 degrees C-1100 degrees C indicate significant strength is retained; even at the highest test temperature, ceramic failure is observed. Post-bonding anneals at 1000 degrees C in vacuum or in gettered argon were used to assess joint stability and to probe the effect of ambient oxygen partial pressure on joint characteristics. Annealing in vacuum for up to 200 h causes no significant decrease in room temperature bend strength or change in fracture path. With increasing anneal time in a lower oxygen partial pressure environment, the fracture strength decreases only slightly, but the fracture path shifts from the ceramic to the interface.« less

Preparation of lead-zirconium-titanium film and powder by electrodeposition

DOEpatents

Bhattacharya, R.N.; Ginley, D.S.

1995-10-31

A process is disclosed for the preparation of lead-zirconium-titanium (PZT) film and powder compositions. The process comprises the steps of providing an electrodeposition bath, providing soluble salts of lead, zirconium and titanium metals to this bath, electrically energizing the bath to thereby direct ions of each respective metal to a substrate electrode and cause formation of metallic particles as a recoverable film of PZT powder on the electrode, and also recovering the resultant film as a powder. Recovery of the PZT powder can be accomplished by continually energizing the bath to thereby cause powder initially deposited on the substrate-electrode to drop therefrom into the bath from which it is subsequently removed. A second recovery alternative comprises energizing the bath for a period of time sufficient to cause PZT powder deposition on the substrate-electrode only, from which it is subsequently recovered. PZT film and powder so produced can be employed directly in electronic applications, or the film and powder can be subsequently oxidized as by an annealing process to thereby produce lead-zirconium-titanium oxide for use in electronic applications. 4 figs.