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Development of a ceramic membrane for upgrading methane to high-value-added clean fuels

Description: The upgrading of natural gas (which consists mostly of methane) to high-value-added clean-burning fuels such as dimethyl ether, alcohols, and pollution-fighting fuel additives is driven by the abundance of natural gas discovered in remote areas. Recently, extensive efforts have focused on both direct and indirect conversion of methane to these value-added products. The direct-conversion route is the most difficult approach because the products are more reactive than the starting reactant, methane. Indirect routes require the partial oxidation of methane to synthesis gas (syngas, CO + H{sub 2}) in a first stage. The syngas is then converted to upgraded products in a second stage. The most significant cost associated with partial oxidation of methane to syngas is that of the oxygen plant. In this paper, we offer a technology that is based on dense ceramic membranes and that uses air as the oxidant for methane-conversion reaction; thus eliminating tile need for the costly oxygen plant. Certain ceramic materials exhibit both electronic and oxide-ionic conductivities. These mixed-conductor materials transport not only oxygen ions (functioning as selective oxygen separators), but also electrons. No external electrodes are required and such a system will operate without an externally applied potential. Oxygen is transported across the ceramic material in the form of oxygen anions, not oxygen molecules.
Date: December 1, 1996
Creator: Balachandran, U.; Dusek, J.T. & Picciolo, J.J.
Partner: UNT Libraries Government Documents Department

Processing and properties of hot-forged bulk superconductors

Description: (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} (Bi-2223) and TlBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} (Tl-1223) bars were hot forged in air at 820--850C. Final stresses of 2--3 MPa were sufficient to produce >95% dense Bi-2223 bars. In contrast, stresses to {approx}42 MPa were able to produce only 75--80% dense Tl-1223 bars. The Bi-2223 bars were more phase-pure and exhibited much stronger c-axis textures than the Tl-1223. Maximum critical current densities at 77 K were 8 {times} 10{sup 4} A/cm{sup 2} for the Bi-2223 and 2 {times} 10{sup 4}/cm{sup 2} for the Tl-1223. Fracture strength and toughness values were 140 MPa and 2.9 MPa{radical}m for the Bi-2223 and 50 MPa and 0.5 MPa{radical}m for the Tl-1223.
Date: December 31, 1995
Creator: Goretta, K.C.; Lanagan, M.T.; Picciolo, J.J.; Youngdahl, C.A.; Balachandran, U. & Chen, Nan
Partner: UNT Libraries Government Documents Department

Hydrogen production by water dissociation using ceramic membranes. Annual report for FY 2007.

Description: The objective of this project is to develop dense ceramic membranes that, without using an external power supply or circuitry, can produce hydrogen via coal/coal gas-assisted water dissociation. This project grew out of an effort to develop a dense ceramic membrane for separating hydrogen from gas mixtures such as those generated during coal gasification, methane partial oxidation, and water-gas shift reactions [1]. That effort led to the development of various cermet (i.e., ceramic/metal composite) membranes that enable hydrogen to be produced by two methods. In one method, a hydrogen transport membrane (HTM) selectively removes hydrogen from a gas mixture by transporting it through either a mixed protonic/electronic conductor or a hydrogen transport metal. In the other method, an oxygen transport membrane (OTM) generates hydrogen mixed with steam by removing oxygen that is generated through water splitting [1, 2]. This project focuses on the development of OTMs that efficiently produce hydrogen via the dissociation of water. Supercritical boilers offer very high-pressure steam that can be decomposed to provide pure hydrogen by means of OTMs. Oxygen resulting from the dissociation of steam can be used for coal gasification, enriched combustion, or synthesis gas production. Hydrogen and sequestration-ready CO{sub 2} can be produced from coal and steam by using the membrane being developed in this project. Although hydrogen can also be generated by high-temperature steam electrolysis, producing hydrogen by water splitting with a mixed-conducting membrane requires no electric power or electrical circuitry.
Date: March 4, 2008
Creator: Balachandran, U.; Chen, L.; Dorris, S. E.; Emerson, J. E.; Lee, T. H.; Park, C. Y. et al.
Partner: UNT Libraries Government Documents Department

Hydrogen separation membranes - annual report for FY 2007.

Description: The objective of this work is to develop dense ceramic membranes for separating hydrogen from other gaseous components in a nongalvanic mode, i.e., without using an external power supply or electrical circuitry.
Date: January 31, 2008
Creator: Chen, L.; Dorris, S. E.; Emerson, J. E.; Lee, T. H.; Park, C. Y.; Picciolo, J. J. et al.
Partner: UNT Libraries Government Documents Department

Hydrogen production by water dissociation using ceramic membranes - annual report for FY 2010.

Description: The objective of this project is to develop dense ceramic membranes that can produce hydrogen via coal/coal gas-assisted water dissociation without using an external power supply or circuitry. This project grew from an effort to develop a dense ceramic membrane for separating hydrogen from gas mixtures such as those generated during coal gasification, methane partial oxidation, and water-gas shift reactions. That effort led to the development of various cermet (i.e., ceramic/metal composite) membranes that enable hydrogen production by two methods. In one method, a hydrogen transport membrane (HTM) selectively removes hydrogen from a gas mixture by transporting it through either a mixed protonic/electronic conductor or a hydrogen transport metal. In the other method, an oxygen transport membrane (OTM) generates hydrogen mixed with steam by removing oxygen that is generated through water splitting. This project focuses on the development of OTMs that efficiently produce hydrogen via the dissociation of water. Supercritical boilers offer very high-pressure steam that can be decomposed to provide pure hydrogen using OTMs. Oxygen resulting from the dissociation of steam can be used for coal gasification, enriched combustion, or synthesis gas production. Hydrogen and sequestration-ready CO{sub 2} can be produced from coal and steam by using the membrane being developed in this project. Although hydrogen can also be generated by high-temperature steam electrolysis, producing hydrogen by water splitting with a mixed-conducting membrane requires no electric power or electrical circuitry.
Date: March 14, 2011
Creator: Balachandran, U.; Dorris, S. E.; Emerson, J. E.; Lee, T. H.; Lu, Y.; Park, C. Y. et al.
Partner: UNT Libraries Government Documents Department

Hydrogen production by water dissociation using ceramic membranes - annual report for FY 2008.

Description: The objective of this project is to develop dense ceramic membranes that, without using an external power supply or circuitry, can produce hydrogen via coal/coal gas-assisted water dissociation. This project grew from an effort to develop a dense ceramic membrane for separating hydrogen from gas mixtures such as those generated during coal gasification, methane partial oxidation, and water-gas shift reactions. That effort led to the development of various cermet (i.e., ceramic/metal composite) membranes that enable hydrogen production by two methods. In one method, a hydrogen transport membrane (HTM) selectively removes hydrogen from a gas mixture by transporting it through either a mixed protonic/electronic conductor or a hydrogen transport metal. In the other method, an oxygen transport membrane (OTM) generates hydrogen mixed with steam by removing oxygen that is generated through water splitting. This project focuses on the development of OTMs that efficiently produce hydrogen via the dissociation of water. Supercritical boilers offer very high-pressure steam that can be decomposed to provide pure hydrogen by means of OTMs. Oxygen resulting from the dissociation of steam can be used for coal gasification, enriched combustion, or synthesis gas production. Hydrogen and sequestration-ready CO{sub 2} can be produced from coal and steam by using the membrane being developed in this project. Although hydrogen can also be generated by high-temperature steam electrolysis, producing hydrogen by water splitting with a mixed-conducting membrane requires no electric power or electrical circuitry.
Date: March 25, 2009
Creator: Balachandran, U.; Dorris, S. E.; Emerson, J. E.; Lee, T. H.; Lu, Y.; Park, C. Y. et al.
Partner: UNT Libraries Government Documents Department

Hydrogen separation membranes annual report for FY 2008.

Description: The objective of this work is to develop dense ceramic membranes for separating hydrogen from other gaseous components in a nongalvanic mode, i.e., without using an external power supply or electrical circuitry. The goal of this project is to develop dense hydrogen transport membranes (HTMs) that nongalvanically (i.e., without electrodes or external power supply) separate hydrogen from gas mixtures at commercially significant fluxes under industrially relevant operating conditions. HTMs will be used to separate hydrogen from gas mixtures such as the product streams from coal gasification, methane partial oxidation, and water-gas shift reactions. Potential ancillary uses of HTMs include dehydrogenation and olefin production, as well as hydrogen recovery in petroleum refineries and ammonia synthesis plants, the largest current users of deliberately produced hydrogen. This report describes progress that was made during Fy 2008 on the development of HTM materials.
Date: March 17, 2009
Creator: Balachandran, U.; Dorris, S. E.; Emerson, J. E.; Lee, T. H.; Lu, Y.; Park, C. Y. et al.
Partner: UNT Libraries Government Documents Department

Hydrogen separation membranes annual report for FY 2010.

Description: The objective of this work is to develop dense ceramic membranes for separating hydrogen from other gaseous components in a nongalvanic mode, i.e., without using an external power supply or electrical circuitry. The goal of this project is to develop dense hydrogen transport membranes (HTMs) that nongalvanically (i.e., without electrodes or external power supply) separate hydrogen from gas mixtures at commercially significant fluxes under industrially relevant operating conditions. These membranes will be used to separate hydrogen from gas mixtures such as the product streams from coal gasification, methane partial oxidation, and water-gas shift reactions. Potential ancillary uses of HTMs include dehydrogenation and olefin production, as well as hydrogen recovery in petroleum refineries and ammonia synthesis plants, the largest current users of deliberately produced hydrogen. This report describes the results from the development and testing of HTM materials during FY 2010.
Date: March 14, 2011
Creator: Balachandran, U.; Dorris, S. E; Emerson, J. E.; Lee, T. H.; Lu, Y.; Park, C. Y. et al.
Partner: UNT Libraries Government Documents Department

Fabrication and characterization of (Bi,Pb)-Sr-Ca-Cu-O (2223) bars

Description: Bulk bars for current lead applications were fabricated from (Bi,Pb)- Sr-Ca-Cu-O (Bi-2223) for low thermal conductivity and high critical current. Bars measuring 17.8 cm in length were made by uniaxially pressing Bi-2223 powder of controlled (1.7/0.34)223 and (1.8/0.4)223 phase composition. The bulk bars were densified by subjecting them to a schedule of alternate liquid-phase sintering and cold isostatic pressing. Liquid phase sintering temperatures were optimized from differential thermal analysis and microstructure morphology. Phase purity and microstructure were evaluated by x-ray diffraction and scanning electron microscopy. Low-resistance silver contacts were applied to the bars by hot-pressing at 820{degrees}C and 3 MPa. Critical current densities {approx} 1000 A/cm{sup 3} (critical currents of 750 A at 77 K in self-field conditions) were achieved.
Date: August 1996
Creator: Chudzik, M. P.; Polzin, B. J.; Thayer, R.; Picciolo, J. J.; Fisher, B. L. & Lanagan, M. T.
Partner: UNT Libraries Government Documents Department

Oxygen-permeable ceramic membranes for gas separation

Description: Mixed-conducting oxides have a wide range of applications, including fuel cells, gas separation systems, sensors, and electrocatalytic equipment. Dense ceramic membranes made of mixed-conducting oxides are particularly attractive for gas separation and methane conversion processes. Membranes made of Sr-Fe-Co oxide, which exhibits high combined electronic and oxygen ionic conductivities, can be used to selectively transport oxygen during the partial oxidation of methane to synthesis gas (syngas, i.e., CO + H{sub 2}). The authors have fabricated tubular Sr{sub 2}Fe{sub 2}CoO{sub 6+{delta}} membranes and tested them (some for more than 1,000 h) in a methane conversion reactor that was operating at 850--950 C. An oxygen permeation flux of {approx} 10 scc/cm{sup 2} {center_dot} min was obtained at 900 C in a tubular membrane with a wall thickness of 0.75 mm. Using a gas-tight electrochemical cell, the authors have also measured the steady-state oxygen permeability of flat Sr{sub 2}Fe{sub 2}CoO{sub 6+{delta}} membranes as a function of temperature and oxygen partial pressure(pO{sub 2}). Steady-state oxygen permeability increases with increasing temperature and with the difference in pO{sub 2} on the two sides of the membrane. At 900 C, an oxygen permeability of {approx} 2.5 scc/cm{sup 2} {center_dot} min was obtained in a 2.9-mm-thick membrane. This value agrees with that obtained in methane conversion reactor experiments. Current-voltage (I-V) characteristics determined in the gas-tight cell indicate that bulk effect, rather than surface exchange effect, is the main limiting factor for oxygen permeation of {approx} 1-mm-thick Sr{sub 2}Fe{sub 2}CoO{sub 6+{delta}} membranes at elevated temperatures (> 650 C).
Date: February 1, 1998
Creator: Balachandran, U.; Ma, B.; Maiya, P.S.; Dusek, J.T.; Mieville, R.L. & Picciolo, J.J.
Partner: UNT Libraries Government Documents Department

Development of mixed-conducting ceramic membranes for converting methane to syngas

Description: The abundantly available natural gas (mostly methane) discovered in remote areas has stimulated considerable research on upgrading this gas to high-value-added clean-burning fuels such as dimethyl ether and alcohols and to pollution-fighting additives. Of the two routes to convert methane to valuable products direct and indirect, the direct route involving partial oxidation of methane to syngas (CO + H{sub 2}) by air is preferred. Syngas is the key intermediate product used to form a variety of petrochemicals and transportation fuels. This paper is concerned with the selective transport of oxygen from air for converting methane to syngas by means of a mixed-conducting ceramic oxide membrane prepared from Sr-Fe-Co-O oxide. While both perovskite and nonperovskite type Sr-Fe-Co-O oxides permeate large amounts of oxygen when the membrane tube is subjected to oxygen pressure gradients, the work shows that the nonperovskite SrFeCo{sub 0.5}O{sub x} exhibits remarkable stability during oxygen permeation. More particularly, extruded and sintered tubes from SrFeCo{sub 0.5}O{sub x} have been evaluated in a reactor operating at {approx} 850 C for conversion of methane into syngas in the presence of a reforming catalyst. Methane conversion efficiencies of {approx} 99% were observed. In addition, oxygen permeability of SrFeCo{sub 0.5}O{sub x} was measured as a function of oxygen partial pressure gradient and temperature in a gas-tight electrochemical cell. Oxygen permeability has also been calculated from conductivity data and the results are compared and discussed.
Date: April 1, 1997
Creator: Balachandran, U.; Maiya, P.S.; Ma, B.; Dusek, J.T.; Mieville, R.L. & Picciolo, J.J.
Partner: UNT Libraries Government Documents Department

Development of fibrous monoliths from mullite, alumina, and zirconia powders

Description: Fibrous monoliths (FMs) based on mullite combined with Al{sub 2}O{sub 3} and Y{sub 2}O{sub 3}-stabilized ZrO{sub 2} have been produced. These FMs incorporate duplex cells in which compressive residual stresses were engineered into the surfaces of the cells. The residual stresses should increase average cell strength, which may allow them to achieve mechanical properties comparable to those of Si{sub 3}N{sub 4}/BN FMs. The expected residual stresses have been calculated, and data on sintering and thermal expansion have been gathered. Prototype FMs were produced and their microstructure examined.
Date: June 29, 2000
Creator: Polzin, B. J.; Cruse, T. A.; Singh, D.; Picciolo, J. J.; Tsaliagos, R. N.; Phelan, P. J. et al.
Partner: UNT Libraries Government Documents Department

Alumina composites for oxide/oxide fibrous monoliths

Description: Most work on ceramic fibrous monoliths (FMs) has focused on the Si{sub 3}N{sub 4}/BN system. In an effort to develop oxidation-resistant FMs, several oxide systems have recently been examined. Zirconia-toughened alumina and alumina/mullite appear to be good candidates for the cell phase of FMs. These composites offer higher strength and toughness than pure alumina and good high-temperature stability. By combining these oxides, possibly with a weaker high-temperature oxide as the cell-boundary phase, it should be possible to product a strong, resilient FM that exhibits graceful failure. Several material combinations have been examined. Results on FM fabrication and microstructural development are presented.
Date: March 1, 2000
Creator: Cruse, T. A.; Polzin, B. J.; Picciolo, J. J.; Singh, D.; Tsaliagos, R. N. & Goretta, K. C.
Partner: UNT Libraries Government Documents Department

Dense ceramic membranes for converting methane to syngas

Description: Dense mixed-oxide ceramics capable of conducting both electrons and oxygen ions are promising materials for partial oxygenation of methane to syngas. We are particularly interested in an oxide based on the Sr-Fe-Co-O system. Dense ceramic membrane tubes have been fabricated by a plastic extrusion technique. The sintered tubes were then used to selectively transport oxygen from air through the membrane to make syngas without the use of external electrodes. The sintered tubes have operated for >1000 h, and methane conversion efficiencies of >98% have been observed. Mechanical properties, structural integrity of the tubes during reactor operation, results of methane conversion, selectivity of methane conversion products, oxygen permeation, and fabrication of multichannel configurations for large-scale production of syngas will be presented.
Date: July 1, 1995
Creator: Balachandran, U.; Dusek, J.T.; Picciolo, J.J.; Ma, B.; Maiya, P.S.; Mieville, R.L. et al.
Partner: UNT Libraries Government Documents Department

Mixed-conducting dense ceramics for gas separation applications.

Description: Mixed-conducting (electronic and ionic conducting) dense ceramics are used in many applications, including fuel cells, gas separation membranes, batteries, sensors, and electrocatalysis. This paper describes mixed-conducting ceramic membranes that are being developed to selectively remove oxygen and hydrogen from gas streams in a nongalvanic mode of operation (i.e., with no electrodes or external power supply). Ceramic membranes made of Sr-Fe-Co oxide (SFC), which exhibits high combined electronic and oxygen ionic conductivities, can be used for high-purity oxygen separation and/or partial oxidation of methane to synthesis gas (syngas, a mixture of CO and H{sub 2}). The electronic and ionic conductivities of SFC were found to be comparable in magnitude. Steady-state oxygen permeability of SFC has been measured as a function of oxygen-partial-pressure gradient and temperature. For an {approx}3-mm-thick membrane, the oxygen permeability was {approx}2.5 scc{center_dot}cm{sup {minus}2}{center_dot}min{sup {minus}1} at 900 C. Oxygen permeation increases as membrane thickness decreases. Tubular SFC membranes have been fabricated and operated at 900 C for {approx}1000 h in converting methane into syngas. The oxygen permeated through the membrane reacted with methane in the presence of a catalyst and produced syngas. We also studied the transport properties of yttria-doped BaCeO{sub 3{minus}{delta}} (BCY) by impedance spectroscopy and open-cell voltage (OCV) measurement. Total conductivity of the BCY sample increased from {approx}5 x 10{sup {minus}3} {Omega}{sup {minus}1}{center_dot}cm{sup {minus}1} to {approx}2 x 10{sup {minus}2} {Omega}{sup {minus}1}{center_dot}cm{sup {minus}1}, whereas the protonic transference number decreased from 0.87 to 0.63 and the oxygen transference number increased from 0.03 to 0.15 as temperature increased from 600 to 800 C. Unlike SFC, in which the ionic and electronic conductivities are nearly equivalent BCY exhibits protonic conductivity that is significantly higher than its electronic conductivity. To enhance the electronic conductivity and therefore to increase hydrogen permeation, metal powder was combined with the BCY to form a cermet membrane, ...
Date: June 22, 1999
Creator: Balachandran, U.; Dorris, S. E.; Dusek, J. T.; Guan, J.; Liu, M.; Ma, B. et al.
Partner: UNT Libraries Government Documents Department

Fabrication and characterization of dense ceramic membranes for partial oxidation of methane

Description: In this technology, air is used as the oxidant for methane conversion reactions, thiu eliminating tne need for an expensive oxygen plant. Mixed-conducting ceramic materials have been produced from mixed-oxide system of the La-Sr-Fe-Co-O (SFC) type, in the form of tubes and bars. Thermodynamic stability of the tubes was studied vs oxygen partial pressure by high-temperature XRD. Mechanical properties of the SFC-2 (SrFeCo{sub 0.5}O{sub x}) material were adequate for reactor use. Electronic and ionic conductivities showed that SFC-2 is unique in that its ratio of ionic to electronic conductance is close to unity. Performance of the membrane tubes was good only with SFC-2. Fracture of other SFC tubes was consequence of an oxygen gradient that introduced a volumetric lattice difference between the inner and outer walls. SFC-2 tubes provided methane conversion efficiencies >99% in a reactor and have operated successfully for >1000 h.
Date: June 1, 1995
Creator: Balachandran, U.; Ma, B.; Dusek, J.T.; Picciolo, J.J.; Mieville, R.L.; Maiya, P.S. et al.
Partner: UNT Libraries Government Documents Department

Dense cermet membranes for hydrogen separation.

Description: Argonne National Laboratory (ANL) and the National Energy Technology Laboratory (NETL) are developing dense ceramic-based membranes for separating hydrogen from the products of coal gasification and other partial-oxidation streams. Hydrogen separation with these membranes is nongalvanic, i.e., it does not use electrodes or an external power supply to drive the separation, and hydrogen selectivity is nearly 100% because the membranes contain no interconnected porosity. Novel cermet (i.e., ceramic-metal composite) membranes have been developed to separate hydrogen from gas mixtures at high temperature and pressure. Hydrogen permeation rates have been measured in the temperature range of 600-900 C for three classes of cermet membranes (ANL-1, -2, and -3). ANL-3a membranes, with a thickness of 40 {micro}m, provide the highest hydrogen flux ({approx}20 cm{sup 3} [STP]/min-cm 2 at 900 C with 100% H{sub 2} as the feed gas). The effects of membrane thickness and hydrogen partial pressure on hydrogen flux indicate that the bulk diffusion of hydrogen is rate-limiting in ANL-3 membranes with a thickness >40 {micro}m. ANL-3b membranes were tested in simulated syngas at several temperatures, and no performance degradation was observed for times that approached {approx}200 h; this observation suggests that the membrane is chemically stable and may be suitable for long-term operation. The performance of membranes in separating hydrogen from high-pressure gas streams is being evaluated with NETL's in-house R and D facilities. The present status of membrane development at ANL/NETL will be presented in this paper.
Date: August 21, 2002
Creator: Dorris, S. E.; Lee, T. H.; Wang, S.; Picciolo, J. J.; Dusek, J. T.; Balachandran, U. et al.
Partner: UNT Libraries Government Documents Department

Atmosphere control during preparation of YBa sub 2 Cu sub 3 O sub 7- x magnet windings

Description: Large coils of YBa{sub 2}Cu{sub 3}O{sub 7-x} can be fired successfully if the furnace atmosphere is carefully controlled. Organics added during processing produce CO{sub 2} during the initial portions of the firing schedule. Transmission electron microscopy of material fired in atmospheres containing various levels of CO{sub 2} clearly shows the extent of grain boundary degradation caused by CO{sub 2}. Coils with acceptable critical current density can be produced if the rate of CO{sub 2} removal is adequate. 9 refs., 4 figs., 1 tab.
Date: October 1, 1990
Creator: Poeppel, R.B.; Dorris, S.E.; Picciolo, J.J.; Balachandran, U.; Lanagan, M.T.; Zhang, C.Z. et al.
Partner: UNT Libraries Government Documents Department

Hydrogen separation membranes annual report for FY 2006.

Description: The objective of this work is to develop dense ceramic membranes for separating hydrogen from other gaseous components in a nongalvanic mode, i.e., without using an external power supply or electrical circuitry. This goal of this project is to develop two types of dense ceramic membrane for producing hydrogen nongalvanically, i.e., without electrodes or external power supply, at commercially significant fluxes under industrially relevant operating conditions. The first type of membrane, hydrogen transport membranes (HTMs), will be used to separate hydrogen from gas mixtures such as the product streams from coal gasification, methane partial oxidation, and water-gas shift reactions. Potential ancillary uses of HTMs include dehydrogenation and olefin production, as well as hydrogen recovery in petroleum refineries and ammonia synthesis plants, the largest current users of deliberately produced hydrogen. The second type of membrane, oxygen transport membranes (OTMs), will produce hydrogen by nongalvanically removing oxygen that is generated when water dissociates at elevated temperatures. This report describes progress that was made during FY 2006 on the development of OTM and HTM materials.
Date: February 5, 2007
Creator: Balachandran, U.; Chen, L.; Ciocco, M.; Doctor, R. D.; Dorris, S.E.; Emerson, J. E. et al.
Partner: UNT Libraries Government Documents Department

Fabrication of ceramic membrane tubes for direct conversion of natural gas

Description: Several perovskite-type oxides that contain transition metals on the B-site show mixed (electronic/ionic) conductivity. These mixed conducting oxides are promising materials for oxygen permeating membranes that can operate without the need of electrodes or external electrical circuitry. SrCo{sub 0.8}Fe{sub 0.2}O{sub x} perovskite is known to exhibit very high oxygen permeabilities and one could use this material for producing value added products by direct conversion of methane, the most abundant component of natural gas. This paper deals with the processing and fabrication by plastic extrusion of long lengths ({approx}30 cm) of hollow SrCo{sub 0.8}Fe{sub 0.2}O{sub x} ceramic tubes. These tubes are characterized by scanning electron microscopy, X-ray diffraction (XRD) and their thermodynamic stability is evaluated using room temperature XRD on samples equilibrated at high temperatures in different gas environment.
Date: May 1, 1992
Creator: Balachandran, U.; Morissette, S. L.; Picciolo, J. J.; Dusek, J. T.; Poeppel, R. B.; Pei, S. et al.
Partner: UNT Libraries Government Documents Department

Development of advanced fibrous monoliths - final report for project of 1998-2000.

Description: Efforts to develop fibrous ceramic monoliths for primarily structural applications are described. Fibrous monoliths (FMs) are relatively insensitive to flaws and can exhibit graceful failure and large work-of-fracture values. They can be inexpensively produced in a wide variety of forms by conventional ceramic processing methods such as extrusion. The FM project that is the subject of this report involved investigations to (1) develop FMs that can be pressureless sintered rather than hot pressed, (2) develop technologies to continuously extrude FM filaments and inexpensively fabricate FM components, (3) evaluate the performance of commercial and new, prototype FMs, (4) develop micromechanical models to guide the design of new FMs and predict their properties, and (5) forge collaborations with industry to produce useful parts.
Date: May 10, 2001
Creator: Goretta, K. C.; Singh, D.; Cruse, T. A.; Ellingson, W. A.; Picciolo, J. J.; Polzin, B. J. et al.
Partner: UNT Libraries Government Documents Department

Practical superconductor development for electrical power applications - annual report for FY 2000.

Description: Most large-scale high-critical-temperature superconductor applications require wires or tapes that an carry high currents in applied magnetic fields. This report describes technical progress of research and development efforts aimed at producing superconducting components and devices in the Y-Ba-Cu-O and Bi-(Pb)-Sr-Ca-Cu-O systems. Topics discussed are formation of first- and second-generation composite conductors, characterization of structures and superconducting and mechanical properties, modeling of grain-boundary current transport, and fabrication and analysis of prototype components.
Date: January 25, 2001
Creator: Balachandran, U.; Cha, Y.S.; Dorris, S.E.; Dusek, J.T.; Emerson, J.E.; Fisher, B.L. et al.
Partner: UNT Libraries Government Documents Department

Practical superconductor development for electrical power applications : annual report for FY 2001.

Description: Most large-scale applications of high-critical-temperature superconductors will require wires or tapes that can carry large current in applied magnetic fields. This report describes research and development efforts at Argonne National Laboratory (ANL) aimed at producing practical superconducting components and devices using the Y-Ba-Cu-O and Bi-(Pb)-Sr-Ca-Cu-O systems. Topics discussed include various methods of forming second- and first-generation composite conductors, characterization of their structures and superconducting and mechanical properties, modeling of grain-boundary current transport, and the testing and modeling of a superconducting fault current limiter.
Date: May 2, 2002
Creator: Cha, Y. S.; Dorris, S. E.; Dusek, J. T.; Emerson, J. E.; Erck, R. A.; Fisher, B. L. et al.
Partner: UNT Libraries Government Documents Department

Effects of atmosphere and heating rate during processing of a ceramic superconductor

Description: Properties of ceramic superconductors depend strongly on the temperature, heating rate, pressure, and atmosphere used during synthesis and fabrication. We have developed a process for synthesizing orthorhombic YBa{sub 2}Cu{sub 3}O{sub x} (123) superconducting powders by calcining the precursor powders under reduced total oxygen pressure. The resultant 123 powders are mixed with organics, and wires and coils are fabricated by extrusion. The wires and coils are fired at a reduced total pressure in flowing O{sub 2} to reduce the concentrations of CO{sub 2}, CO, and H{sub 2}O and thus prevent decomposition of the 123. Transport critical current density of the superconductor decreases drastically with increasing concentrations of CO{sub 2} in the gas mixture. Transmission electron microscopy of materials sintered in O{sub 2} atmospheres containing various levels of CO{sub 2} clearly shows the extent of grain boundary degradation. 29 refs., 9 figs., 2 tabs.
Date: January 1, 1991
Creator: Balachandran, U.; Xu, D.; Zhang, C.; Dorris, S.E.; Russell, R.A.; Dusek, J.T. et al.
Partner: UNT Libraries Government Documents Department