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Sample records for ii ybco ceramic

  1. Test Status for Proposed Coupling of a Gravitational Force to Extreme Type II YBCO Ceramic Superconductors

    NASA Technical Reports Server (NTRS)

    Noever, David; Li, Ning; Robertson, Tony; Koczor, Ron; Brantley, Whitt

    1999-01-01

    As a Bose condensate, superconductors provide novel conditions for revisiting previously proposed couplings between electromagnetism and gravity. Strong variations in Cooper pair electron density, large conductivity and low magnetic permeability define superconductive and degenerate condensates without the traditional density limits imposed by the Fermi energy (about 10-6 g/cu cm). Recent experiments have reported anomalous weight loss for a test mass suspended above a rotating Type II, YBCO superconductor, with the percentage change (0.05-2.1%) independent of the test mass' chemical composition and diamagnetic properties. A variation of 5 parts per 10(exp 4) was reported above a stationary (non-rotating) superconductor. In the present experiments reported using a sensitive gravimeter (resolution <10(exp -9) unit gravity or variation of 10(exp -6) cm/sq s in accelerations), bulk YBCO superconductors were stably levitated in a DC magnetic field (0.6 Tesla) subject to lateral AC fields (60 Gauss at 60 Hz) and rotation. With magnetic shielding, thermal control and buoyancy compensation, changes in acceleration were measured to be less than 2 parts in 10(exp 8) of the normal gravitational acceleration. This result puts new limits on the strength and range of the proposed coupling between high-Tc superconductors and gravity. Latest test results will be reported, along with status for future improvements and prospects.

  2. Magnetic memory in a ceramic YBCO superconductor composed of sub-micron-size grains

    NASA Astrophysics Data System (ADS)

    Deguchi, Hiroyuki; Ashida, Takuya; Syudo, Mitsuhiro; Mito, Masaki; Takagi, Seishi; Hagiwara, Makoto; Koyama, Kuniyuki

    2013-06-01

    The ceramic YBa2Cu4O8 (YBCO) composed of sub-micron-size grains is considered as a random Josephson-coupled network of 0 and π junctions and shows successive phase transitions. The first transition occurs inside each grain at T c1 = 81 K, and the second transition occurs among the grains at T c2 = 47 K. A magnetic glass behavior similar to those of spin-glasses is observed at temperatures below T c2. The memory phenomena are investigated by recording the zero-fieldcooled and thermoremanent magnetizations measured on heating after the cooling process with a halt at T s = 41 K. Memory effects of the halt are imprinted in the system when the sample is re-heated. In the case without a field switch at T s , the influence of the halt is confined to a narrow temperature region near T s whereas the memory effect of the halt employing a field switch is extended over a wide temperature region below T s . The results suggest that chiral-glass ordering occurs at T c2 in the ceramic YBCO.

  3. Na-doping effect on the magnetic properties of the YBCO ceramics

    NASA Astrophysics Data System (ADS)

    Nurgaliev, T.; Miteva, S.; Nedkov, I.; Veneva, A.; Taslakov, M.

    1994-11-01

    The ac magnetization and the microwave surface resistance (at 12 GHz were measured on a series of Na-doped YBCO ceramic samples at 77 K. Their magnetic behavior was explained on the basis of the modified critical state model by taking into account the exsitence of a field-dependent component J(sub c1) (due to weakly linked grains) and a field-independent component J(sub c0) (due to perfectly linked grains) in the bulk critical current density of the samples. The Na and Cu remaining after the heat treatment of the samples changed the intergranular medium parameters and impeded the correlation between the grains. As a result, an increase of the Na concentration led to a decrease of the specimens critical current density and an increase of their surface resistance. At small Na concentrations, a certain increase of J(sub c1) was observed, which can be explained by taking into account the possibility of partial pinning of Josephson vortices in the 'weakly seeded' places in the intergranular media.

  4. Comparison of Hall effect near T c in YBCO 123 single crystal and 124 ceramics

    NASA Astrophysics Data System (ADS)

    Affronte, M.; Decroux, M.; Sadowski, W.; Graf, T.; Fischer, Ø.

    1990-12-01

    We have measured the Hall voltage VH as a function of temperature and magnetic field B (up to 6 T) near Tc in Y 1Ba 2Cu 3 O 7-δ (“123”) single crystal and in Y 1Ba 2Cu 4O 8 (“124”) ceramics. Near Tc, VH shows a sign reversal in the 123 crysta l ( B parallel to the c-axis) and the tangents to the VH versus B curves at 6 T do not cross the origin. These features are not observed in the 124 phase. The fact that a negative VH appears in the 123 phase and not in 124 seems to reflect different conditions for the flux flow dynamics in the two compounds. We also report measurements of the normal state Hall coefficient RH obtained in single phase 124 ceramics. The very small value of RH (1.5×10 -10m 3/C for T > 140 K) is rather unusual in the superconducting oxide family.

  5. Fractography of glasses and ceramics II

    SciTech Connect

    Frechette, V.D.; Varner, J.R.

    1991-01-01

    Topics addressed include finite element stress analysis and crack path prediction of imploding CRT; fractography and fracture mechanics of combustion growth diamond thin films; the fracture behavior of machineable hydroxyapatite; a fractal approach to crack branching (bifurcation) in glass; the fracture of glass-ionomer cements; the effect of quartz particle size on the strength and toughness of whitewares; and a proposed standard practice for fractographic analysis of monolithic advanced ceramics. Also treated are thermal exposure effects on ceramic matrix composites, fractography applied to rock core analysis, fractography of flexurally fractured glass rods, the fractographic determination of K(IC) and effects of microstructural effects in ceramics.

  6. Combined mode I and mode II fracture of monolithic ceramics

    NASA Technical Reports Server (NTRS)

    Tikare, Veena; Choi, Sung R.

    1993-01-01

    The mode I, mode II, and combined mode I-mode II fracture behaviors of a coarse-grained silicon nitride, a fine-grained silicon nitride, and an alumina were investigated. These ceramics were fractured from two types of fracture initiating flaws: small surface flaws and large single edge precracks. The small surface flaws were introduced by Knoop indentation in flexural samples at various angles to the tensile stress direction and fractured in four-point bending. The samples with large precracks were fractured in the asymmetric four-point-bend geometry. The mixed-mode fracture toughness values obtained from the two flaw configurations were in good agreement with each other. All three ceramics displayed very similar mixed-mode fracture behavior, although their microstructures were not similar. Comparison of experimental data to mixed-mode fracture theories revealed that the minimum strain energy density theory best described the mixed-mode fracture behavior of all three ceramics.

  7. Continuous fiber ceramic composites. Phase II - Final report

    SciTech Connect

    Bird, James

    1997-10-31

    This report documents Atlantic Research Corporation's (ARC) Phase 11 effort on the Department of Energy's (DOE) Continuous Fiber Ceramic Composite (CFCC) program. This project is supported by the DOE cooperative agreement DE-FCO2-92CE40998. Such DOE support does not constitute an endorsement of the views expressed in this report. ARC'S CFCC Phase II effort began during October 1993 and was suspended in March of 1997 when, for business considerations, ARC closed the Amercom operation. This report covers progress from Phase II program inception through Amercom closure. ARC'S Phase II effort built upon the results of the Phase I Applications Assessment and Process Engineering developments to produce CFCC test components for end-user evaluation. Initially, the Phase 11 effort planned to develop and produce three CFCC components: CFCC compression rings for stationary diesel engines, CFCC hot gas fans for industrial furnace applications, and CFCC hot gas filters for current and advanced coal fired power cycles. As the program progressed, the development effort for the diesel engine piston rings was suspended. This decision was based on technical issues, cost factors and reduced program funding; the status of CFCC diesel engine piston ring development will be discussed in detail in section 2.2.1.

  8. Fracture toughness of polycrystalline ceramics in combined mode I and mode II loading

    NASA Technical Reports Server (NTRS)

    Singh, Dileep; Shetty, Dinesh K.

    1989-01-01

    The present investigation of the fracture of alumina and zirconia polycrystalline ceramic specimens of precracked-disk type, in diametral compression, evaluated fracture toughness in pure mode I, combined mode I/mode II, and pure mode II, depending on the alignment of the center crack relative to the loading diameter. The mixed-mode fracture-toughness envelope thus obtained exhibits significant deviation to higher fracture toughness in mode II, relative to the predictions of linear elastic fracture mechanics theory. Crack-surface resistance due to grain-interlocking and abrasion are identified as the primary sources of increased fracture resistance in mode II loading of the polycrystalline ceramics.

  9. YBCO COATED CONDUCTORS

    SciTech Connect

    Paranthaman, Mariappan Parans

    2010-01-01

    Since the discovery of high-temperature superconductors (HTS) in 1986, both (Bi,Pb)2Sr2Ca2Cu3O10 (BSCCO or 2223 with a critical temperature, Tc of 110 K) and YBa2Cu3O7- (YBCO or 123 with a Tc of 91 K) have emerged as the leading candidate materials for the first generation (1G) and second generation (2G) high temperature superconductor wires or tapes that will carry high critical current density in liquid nitrogen temperatures [1-7]. The crystal structures and detailed fundamental properties of BSCCO and YBCO superconductors have been reviewed by Matsumoto in a separate chapter in this book. The U.S. Department of Energy s target price for the conductor is close to the current copper wire cost of $10-50/kA-meter, i.e. a meter of copper type conductor carrying 1000 A current costs ~ $ 50 [8]. The long-term goal for the DOE, Office of Electricity, Advanced Conductors and Cables program is to achieve HTS wire in 1000 meters long with current carrying capacity of 1000 A/cm [8]. Robust, high-performance HTS wire will certainly revolutionize the electric power grid and various other electric power equipments as well. Sumitomo Electric Power (Japan) has been widely recognized as the world leader in manufacturing the first-generation HTS wires based on BSCCO materials using the Oxide-Powder-In-Tube (OPIT) over-pressure process [9]. Typically, 1G HTS wires carry critical currents, Ic, of over 200 Amperes (A) in piece lengths of one kilometer lengths at the standard 4 mm width and ~ 200 m thickness. However, due to the higher cost of 1G wire, mainly because of the cost of Ag alloy sheath, the researchers shifted their effort towards the development of YBCO (second generation 2G) tapes in the last fifteen years [1-7]. One of the main obstacles to the ability to carry high critical currents in YBCO films has been the phenomenon of weak links, i.e., grain boundaries formed by the misalignment of neighboring YBCO grains are known to form obstacles to current flow [10]. By

  10. Microstructural effects on fracture toughness of polycrystalline ceramics in combined mode I and mode II loading

    NASA Technical Reports Server (NTRS)

    Singh, D.; Shetty, D. K.

    1988-01-01

    Fracture toughness of polycrystalline alumina and ceria partially-stabilized tetragonal zirconia (CeO2-TZP) ceramics were assessed in combined mode I and mode II loading using precracked disk specimens in diametral compression. Stress states ranging from pure mode I, combined mode I and mode II, and pure mode II were obtained by aligning the center crack at specific angles relative to the loading diameter. The resulting mixed-mode fracture toughness envelope showed significant deviation to higher fracture toughness in mode II relative to the predictions of the linear elastic fracture mechanics theory. Critical comparison with corresponding results on soda-lime glass and fracture surface observations showed that crack surface resistance arising from grain interlocking and abrasion was the main source of the increased fracture toughness in mode II loading of the polycrystalline ceramics. The normalized fracture toughness for pure mode II loading, (KII/KIc), increased with increasing grain size for the CeO2-TZP ceramics. Quantitative fractography confirmed an increased percentage of transgranular fracture of the grains in mode II loading.

  11. Adsorption isotherm studies of Cu (II) and Co (II) in high concentration aqueous solutions on photocatalytically modified diatomaceous ceramic adsorbents

    NASA Astrophysics Data System (ADS)

    Ajenifuja, E.; Ajao, J. A.; Ajayi, E. O. B.

    2017-01-01

    Photocatalytically modified ceramic adsorbents were synthesized for the removal of high concentration Cu (II) and Co (II) ions from their aqueous solutions. The raw material, diatomaceous aluminosilicate mineral was modified using silver and anatase titanium oxide nanoparticles. Batch adsorption experiment was carried out on the targeted metal ions and the results were analyzed by the Langmuir and Freundlich equation at different concentrations (100-1000 mg/l) and the characteristic parameters for each adsorption isotherm were determined. As-received raw materials do not exhibit any sorption capacity for high concentration Cu2+ and Co2+ adsorbates. However, the adsorption isotherms for modified diatomaceous ceramic adsorbents could be fitted well by the Langmuir model for both Cu2+ and Co2+ with correlation coefficient (R) of up to 0.99953. The highest and lowest monolayer coverage (q max) were 121.803 and 31.289 mg/g for Cu2+ and Co2+, respectively. The separation factor (R L) in the experiment was less than one (<1), indicating that the adsorption of metal ions on the Ag-TiO2-modified ceramic adsorbent is favorable. The highest adsorption capacity (K f) and intensity (n) constants obtained from Freundlich model are 38.832 (Cu2+ on ZEO-T) and 5.801 (Co2+ on STOX-Z).

  12. Magnesium oxide-impregnated tuff soil-derived ceramic: a novel cadmium(II) adsorbing media

    NASA Astrophysics Data System (ADS)

    Salim, Md; Bhakta, Jatindra N.; Maneesh, Namburath; Munekage, Yukihiro; Motomura, Kevin

    2015-07-01

    The contamination of cadmium (Cd) in the aquatic environment is one of the serious environmental and human health's risks. The present study attempted to develop the potential magnesium oxide (MgO)-impregnated tuff soil-derived ceramic (MITDC)-based novel adsorbent media for adsorbing higher rate of cadmium [Cd(II)] from water phase. A potential MITDC adsorbent media was developed using volcanic raw tuff soil and its Cd(II) adsorption capacity from water phase was evaluated comparing with the raw tuff soil. A series of studies were carried out in an agitated batch method at 20 ± 2 °C to characterize the adsorption capacity of MITDC under different conditions of factors, such as contact time (0-360 min), initial pH (3-11) of solution, dose of MITDC (2, 5, 7.5 and 10 g/L), and initial concentration of Cd(II) (5, 10, 20, 30, and 40 mg/L), influencing the adsorption mechanism. MITDC exhibited the equilibrium state of maximum Cd(II) adsorption at the contact time 120 min and pH 4.7 (removed 98.2 % Cd) when initial Cd(II) concentration was 10 mg/L in the present study. The dose of 7.5 g MITDC/L showed maximum removal of Cd(II) from water. Experimental data were described by the Freundlich and the Langmuir isotherms and equilibrium data fitted well with the Langmuir model (R 2 = 0.996). The Cd(II) adsorption capacity of MITDC was 31.25 mg/g. The high Cd(II) adsorption capacity indicated that novel MITDC could be used as a potential ceramic adsorbent media to remove high rate of Cd(II) from aqueous phase.

  13. Transparent BaCl II:Eu 2+ glass-ceramic scintillator

    NASA Astrophysics Data System (ADS)

    Chen, Gang; Johnson, Jacqueline; Schweizer, Stefan; Woodford, John; Newman, Peter; MacFarlane, Douglas

    2006-03-01

    Scintillators are the backbone of high-energy radiation detection devices. Most scintillators are based on inorganic crystals that have applications in medical radiography, nuclear medicine, security inspection, dosimetry, and high-energy physics. In this paper, we present a new type of scintillator that is based on glass ceramics (composites of glasses and crystals). These scintillators are made from Eu 2+-activated fluorozirconate glasses that are co-doped with Ba 2+, La 3+, Al 3+, Na +, and Cl -. Subsequent heat treatment of the glasses forms BaCl II nano-crystals (10-20 nm in size) that are embedded in the glass matrix. The resulting scintillators are transparent, efficient, inexpensive to fabricate, and easy to scale up. The physical structure and x-ray imaging performance of these glass-ceramic scintillators are presented, and an application of these materials to micro-computed tomography is demonstrated. Our study suggests that these glass-ceramic scintillators have high potential for medical x-ray imaging.

  14. SCALE UP OF CERAMIC WASTE FORMS FOR THE EBR-II SPENT FUEL TREATMENT PROCESS

    SciTech Connect

    Matthew C. Morrison; Kenneth J. Bateman; Michael F. Simpson

    2010-11-01

    ABSTRACT SCALE UP OF CERAMIC WASTE FORMS FOR THE EBR-II SPENT FUEL TREATMENT PROCESS Matthew C. Morrison, Kenneth J. Bateman, Michael F. Simpson Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID 83415 The ceramic waste process is the intended method for disposing of waste salt electrolyte, which contains fission products from the fuel-processing electrorefiners (ER) at the INL. When mixed and processed with other materials, the waste salt can be stored in a durable ceramic waste form (CWF). The development of the CWF has recently progressed from small-scale testing and characterization to full-scale implementation and experimentation using surrogate materials in lieu of the ER electrolyte. Two full-scale (378 kg and 383 kg) CWF test runs have been successfully completed with final densities of 2.2 g/cm3 and 2.1 g/cm3, respectively. The purpose of the first CWF was to establish material preparation parameters. The emphasis of the second pre-qualification test run was to evaluate a preliminary multi-section CWF container design. Other considerations were to finalize material preparation parameters, measure the material height as it consolidates in the furnace, and identify when cracking occurs during the CWF cooldown process.

  15. Origin of photovoltaic effect in superconducting YBa2Cu3O6.96 ceramics.

    PubMed

    Yang, F; Han, M Y; Chang, F G

    2015-06-23

    We report remarkable photovoltaic effect in YBa2Cu3O6.96 (YBCO) ceramic between 50 and 300 K induced by blue-laser illumination, which is directly related to the superconductivity of YBCO and the YBCO-metallic electrode interface. There is a polarity reversal for the open circuit voltage Voc and short circuit current Isc when YBCO undergoes a transition from superconducting to resistive state. We show that there exists an electrical potential across the superconductor-normal metal interface, which provides the separation force for the photo-induced electron-hole pairs. This interface potential directs from YBCO to the metal electrode when YBCO is superconducting and switches to the opposite direction when YBCO becomes nonsuperconducting. The origin of the potential may be readily associated with the proximity effect at metal-superconductor interface when YBCO is superconducting and its value is estimated to be ~10(-8) mV at 50 K with a laser intensity of 502 mW/cm(2). Combination of a p-type material YBCO at normal state with an n-type material Ag-paste forms a quasi-pn junction which is responsible for the photovoltaic behavior of YBCO ceramics at high temperatures. Our findings may pave the way to new applications of photon-electronic devices and shed further light on the proximity effect at the superconductor-metal interface.

  16. Origin of photovoltaic effect in superconducting YBa2Cu3O6.96 ceramics

    PubMed Central

    Yang, F.; Han, M. Y.; Chang, F. G.

    2015-01-01

    We report remarkable photovoltaic effect in YBa2Cu3O6.96 (YBCO) ceramic between 50 and 300 K induced by blue-laser illumination, which is directly related to the superconductivity of YBCO and the YBCO-metallic electrode interface. There is a polarity reversal for the open circuit voltage Voc and short circuit current Isc when YBCO undergoes a transition from superconducting to resistive state. We show that there exists an electrical potential across the superconductor-normal metal interface, which provides the separation force for the photo-induced electron-hole pairs. This interface potential directs from YBCO to the metal electrode when YBCO is superconducting and switches to the opposite direction when YBCO becomes nonsuperconducting. The origin of the potential may be readily associated with the proximity effect at metal-superconductor interface when YBCO is superconducting and its value is estimated to be ~10–8 mV at 50 K with a laser intensity of 502 mW/cm2. Combination of a p-type material YBCO at normal state with an n-type material Ag-paste forms a quasi-pn junction which is responsible for the photovoltaic behavior of YBCO ceramics at high temperatures. Our findings may pave the way to new applications of photon-electronic devices and shed further light on the proximity effect at the superconductor-metal interface. PMID:26099727

  17. Ceramics reinforced metal base composite coatings produced by CO II laser cladding

    NASA Astrophysics Data System (ADS)

    Yang, Xichen; Wang, Yu; Yang, Nan

    2008-03-01

    Due to the excellent performance in high strength, anti-temperature and anti-wear, ceramics reinforced metal base composite material was used in some important fields of aircraft, aerospace, automobile and defense. The traditional bulk metal base composite materials are the expensive cost, which is limited in its industrial application. Development of laser coating of ceramics reinforced metal base composite is very interesting in economy. This paper is focused on three laser cladding ceramics coatings of SiC particle /Al matrix , Al IIO 3 powder/ Al matrix and WC + Co/mild steel matrix. Powder particle sizes are of 10-60μm. Chemical contents of aluminum matrix are of 3.8-4.0% Cu, 1.2-1.8% Mg, 0.3-0.99% Mn and balance Al. 5KW CO II laser, 5 axes CNC table, JKF-6 type powder feeder and co-axis feeder nozzle are used in laser cladding. Microstructure and performance of laser composite coatings have been respectively examined with OM,SEM and X-ray diffraction. Its results are as follows : Microstructures of 3C-,6H- and 5H- SiC particles + Al + Al 4SiC 4 + Si in SiC/Al composite, hexagonal α-Al IIO 3 + cubic γ-Al IIO 3 + f.c.c Al in Al IIO 3 powder/ Al composite and original WC particles + separated WC particles + eutectic WC + γ-Co solid solution + W IIC particles in WC + Co/steel coatings are respectively recognized. New microstructures of 5H-SiC in SiC/Al composite, cubic γ-Al IIO 3 in Al IIO 3 composite and W IIC in WC + Co/ steel composite by laser cladding have been respectively observed.

  18. Microwave characterization of normal and superconducting states of MOCVD made YBCO tapes

    NASA Astrophysics Data System (ADS)

    Wosik, Jarek; Krupka, Jerzy; Qin, Kuang; Ketharnath, Dhivya; Galstyan, Eduard; Selvamanickam, Venkat

    2017-03-01

    We have used a microwave, non-contact, non-destructive, dielectric resonator (DR) technique to characterize complex conductivity of different quality YBCO/Hastelloy tapes for the purpose of exploring such a technique as a potential quality control method for fabrication of YBCO tapes. The tapes were deposited at different temperatures on Hastelloy-supported oxide buffer layers using the MOCVD technique. The buffer stack consisted of aluminum oxide (Al2O3), yttrium oxide (Y2O3), and textured ion beam assisted deposition-MgO and LaMnO3 layers. Two dielectric resonators (DRs), the single post DR, consisting of high-permittivity barium zirconium titanate ceramic operating at 13 GHz in quasi-TE01δ mode, and the rod DR, consisting of rutile single crystal disk operating at 9.4 GHz in-TE011 mode, were designed to meet sensitivity requirements for characterization of conductivity of the superconductor at normal and superconducting states, respectively. For calculations of complex conductivity from experimental data of Q-factor and resonant frequency shift, a commercial electromagnetic simulator HFSS, based on finite elements analysis, was used. The theoretical Q-factor and resonant frequency on conductivity functions obtained from full wave numerical simulations of microwave fields were matched with the experimental data to determine conductivity of the YBCO tapes in both normal and superconducting states. In addition, for comparison purposes, 280 nm thick high-quality YBCO epitaxial film deposited on a dielectric substrate was also characterized, including frequency dependence of the complex conductivity. Discussion about feasibility of using DR microwave techniques as a quality control tool via measurements of conductivity versus temperature slope of the YBCO/Hastelloy tape in normal state is included. Also, microwave conductivity values of Hastelloy substrate as a function of temperature are reported.

  19. Development of HTS power cable using YBCO coated conductor

    NASA Astrophysics Data System (ADS)

    Mukoyama, Shinichi; Yagi, Masashi; Hirano, Hironobu; Yamada, Yutaka; Izumi, Teruo; Shiohara, Yuh

    2006-10-01

    Reductions of AC losses and of cost of HTS power cables are important to put it into practical power networks. Since an YBCO-coated-conductor (YBCO tape) has higher Jc and better magnetic property than a Bi2223-Ag-sheathed-tape, an AC power cable using YBCO tapes will obtain higher performance than XLPE-cables and HTS cables using BSCCO tapes in future. Especially, an YBCO HTS cable will be expected to become a higher economical cable than a Bi cable because an YBCO tape reduced its AC losses and its wire cost. We have started developing HTS power cables using YBCO tapes. Mechanical properties, superconducting properties and other electro magnetic properties of YBCO tapes have been measured to estimate the applicability to the HTS cable. Moreover, we have developed some technologies to bring out latent potentials of YBCO tapes.

  20. Interlayer structure in YBCO-coated conductors prepared by chemical solution deposition

    NASA Astrophysics Data System (ADS)

    Molina-Luna, Leopoldo; Egoavil, Ricardo; Turner, Stuart; Thersleff, Thomas; Verbeeck, Jo; Holzapfel, Bernhard; Eibl, Oliver; Van Tendeloo, Gustaaf

    2013-07-01

    The functionality of YBa2Cu3O7-δ (YBCO)-coated conductor technology depends on the reliability and microstructural properties of a given tape or wire architecture. Particularly, the interface to the metal tape is of interest since it determines the adhesion, mechanical stability of the film and thermal contact of the film to the substrate. A trifluoroacetate (TFA)—metal organic deposition (MOD) prepared YBCO film deposited on a chemical solution-derived buffer layer architecture based on CeO2/La2Zr2O7 and grown on a flexible Ni5 at.%W substrate with a {100}<001> biaxial texture was investigated. The YBCO film had a thickness was 440 nm and a jc of 1.02 MA cm-2 was determined at 77 K and zero external field. We present a sub-nanoscale analysis of a fully processed solution-derived YBCO-coated conductor by aberration-corrected scanning transmission electron microscopy (STEM) combined with electron energy-loss spectroscopy (EELS). For the first time, structural and chemical analysis of the valence has been carried out on the sub-nm scale. Intermixing of Ni, La, Ce, O and Ba takes place at these interfaces and gives rise to nanometer-sized interlayers which are a by-product of the sequential annealing process. Two distinct interfacial regions were analyzed in detail: (i) the YBCO/CeO2/La2Zr2O7 region (10 nm interlayer) and (ii) the La2Zr2O7/Ni-5 at.%W substrate interface region (20 nm NiO). This is of particular significance for the functionality of these YBCO-coated conductor architectures grown by chemical solution deposition.

  1. Materials Science and Technology, Volume 17B, Processing of Ceramics Part II

    NASA Astrophysics Data System (ADS)

    Brook, Richard J.

    1996-12-01

    Progress in the processing of ceramics has made these materials very important for current and future technologies. Internationally renowned experts have contributed to this second of two volumes which provide a wealth of information indispensable for materials scientists and engineers. Contents of Volume B: Riedel: Advanced Ceramics from Inorganic Polymers. Calvert: Biomimetic Processing. Eisele: Sintering and Hot Pressing. Kwon: Liquid-Phase Sintering. Leriche/Cambier: Vitrification. Larker/Larker: Hot Isostatic Pressing. Harmer/Chan: Fired Microstructures and Their Charactzerization. Subramanian: Finishing. Nicholas: Joining of Ceramics. Hirai: Functional Gradient Materials.

  2. Comparative evaluation of microleakage in class II cavities restored with Ceram X and Filtek P-90: An in vitro study

    PubMed Central

    Bogra, Poonam; Gupta, Saurabh; Kumar, Saru

    2012-01-01

    Context: Polymerization shrinkage in composite resins is responsible for microleakage. Methacrylate-based composite resins have linear reactive groups resulting in high polymerization shrinkage. A recently introduced composite resin Filtek P90 is based on siloxanes and oxiranes which polymerize by cationic “ring opening” polymerization resulting in reduced polymerization shrinkage. Objectives: Aim of this study was to compare microleakage in class II cavities restored with a nanoceramic restorative (Ceram X) and a silorane composite (Filtek P90). Materials and Methods: Standardized class II box type cavities were prepared on mesial (Groups Ia and IIa) and distal (Groups Ib and IIb) surfaces of twenty extracted permanent molar teeth with gingival floor ending 1 mm coronal and apical to the cementoenamel junction, respectively. The teeth in Group Ia and Ib were restored with Ceram X and Group IIa and IIb with Filtek P90. The specimens were thermocycled and microleakage evaluated. Statistical Analysis Used: The data were statistically analyzed using Wilcoxon Signed-Rank test at the 0.05 level of significance. Results: Mean microleakage score of group la and lb was 1 ± 2.260 and 2.8 ± 1.229, respectively. And that of group Ila and llb was 0.2 ± .869 and 0.3 ± .588, respectively. When groups I and II were compared, results were statistically significant (P<0.05). Conclusion: It was concluded that silorane-based composite may be a better substitute for methacrylate-based composites. PMID:22557890

  3. Preparation of YBCO-BYTO and YBCO-BZO nanostructured superconducting films by chemical method

    NASA Astrophysics Data System (ADS)

    Garcés, P.; Coll, M.; Castro, H.; Puig, T.; Obradors, X.

    2017-01-01

    YBCO-BYTO6% and YBCO-BZO10% YBa2Cu3O7-d-Ba2YTaO6 6% (YBCO-BYTO6%) and YBa2Cu3O7--BaZrO3 10% (YBCO-BZO 10%) nanostructured films were grown by the Chemical Solution Deposition method, and compared with YBCO pure films. Films were deposited on YSZ substrates, with Ce0.9Zr0.1O2 and Ce0.6Zr0.4O2 buffer layers. They were characterized by GADDS X-ray diffraction, scanning electron microscopy (SEM) and inductive (SQUID) measurements of the critical temperature (Tc) and critical current density (Jc). It was found that YBCO-BZO10% films presented better superconducting properties (Tc=89.2K and Jc=1.3MA/cm2), probably due to an enhanced pinning force, originated by BZO nanoparticles. Additionally, it was found that these films have lower reactivity with the buffer layer.

  4. Superconducting Generators for Airborne Applications and YBCO-Coated Conductors (Preprint)

    DTIC Science & Technology

    2008-10-01

    This work was supported in part by the U.S. Air Force Research Laboratory and Air Force Office of Scientific Research. P . N...Advancing YBCO Coated Conductors for Use on Air Platforms,” Int. J. Appl. Ceramic Technol., vol. 4, pp. 242-249, July 2007. [3] A. P . Malozemoff, S...Fleshler, M. Rupich, C. Thieme, X. Li, W. Zhang, A. Otto, J. Maguire, D. Folts, J. Yuan, H- P . Kraemer, W. Schmidt, M. Wohlfart, and H-W. Neumueller

  5. Transport AC Losses in Striated YBCO Coated Conductors (Postprint)

    DTIC Science & Technology

    2012-02-01

    AFRL-RZ-WP-TP-2012-0124 TRANSPORT AC LOSSES IN STRIATED YBCO COATED CONDUCTORS (POSTPRINT) G.A. Levin and P.N. Barnes Mechanical Energy...TRANSPORT AC LOSSES IN STRIATED YBCO COATED CONDUCTORS (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...2006. 14. ABSTRACT DC current-voltage characteristics and transport ac losses of striated and non-striated Y1Ba2Cu3O7-δ ( YBCO ) coated conductors

  6. Structural Characterization of the Ag/ybco Interface

    NASA Astrophysics Data System (ADS)

    Tidjani, Mohammed Elkhamis

    1990-01-01

    The present research is intended to characterize the interface microstructure and long term stability of the deposited silver metal in contact to the superconducting oxide YBa_2Cu_3O _{rm 7-x} (YBCO). High resolution transmission electron microscopy (HRTEM) observations of the interfacial regions reveal that Ag contacts to YBCO occurred without any intermediate phase formation at the interface. The Ag metal exhibits a preferred orientation relationship with YBCO, in which the densely packed planes and directions of the metal are parallel to those of the superconductor. The formation of (111) interfaces and facets during deposition indicates that these planes are associated with the lowest interfacial energy. The as-deposited Ag film exhibits a granular morphology, and the Ag grains are often twinned along the (111) plane while the surface of YBCO is mostly rough and structurally unstable. Annealing of the Ag/YBCO interface resulted in outdiffusion of yttrium and oxygen at regions where the surface of YBCO was rough. This diffusion, however, did not result in the formation of continuous layers at the Ag/YBCO interface but only to growth of Ag_2 Y and Ag_2O inclusions. Thus it is believed that the stability of the Ag/YBCO depends on the quality of the surface of YBCO, especially its structure. Treatment of the surface of YBCO by ion-bombardment yielded flat surfaces but damaged a layer of about 30A. Such a cleaning process improved the quality of the deposited Ag since the Ag grains were larger and contained low defects concentration. The same orientation relationships between Ag and YBCO were observed after cleaning the surface of YBCO which implied that the destruction of the structure at the surface is only partial. Deposition of Ag in the same chamber where YBCO was initially grown, to minimize the contamination of the surface of YBCO, also was not effective in enhancing the structure of the Ag/YBCO interface. The roughness of the surface of YBCO did not decrease

  7. Improved transport properties of polycrystalline YBCO thin-films

    NASA Astrophysics Data System (ADS)

    Azoulay, J.; Verdyan, A.; Lapsker, I.

    1994-12-01

    Resistive evaporation technique was used to fabricate polycrystalline YBaCuO and YBaNaCuO thin films on MgO substrates. Heat treatment was carried out in a low oxygen partial pressure. Polycrystalline YBCO and Na doped YBCO thin films samples were thus obtained using the same technique and conditions. The critical current density of Na doped YBCO sample was measured to be significantly higher than that of the undoped YBCO one. The results are discussed in terms of the Na contribution to the intragrain conductivity.

  8. Mechanical, Mathematical, and Computer Modeling in Penetration Mechanics - IV (Hybrid Models for Nanostructured Ceramics - II)

    DTIC Science & Technology

    2006-11-30

    model of penetration of long elastically deformable projectiles into semi- infinite targets 3 Introduction 3 1. Basic model equations of penetration...of non- deformable projectiles into semi-infinite target 4 1.1. Geometrical scheme of penetration model of non- deformable projectile 4 1.2. Velocity...c. 20 1.3. Pulverized region (a < r < b). 22 2. Example 25 III. Investigation of deformation process at high-speed loadings of ceramic materials

  9. Improving YBCO Coated Conductors for Applications (Postprint)

    DTIC Science & Technology

    2012-02-01

    are lighter in weight and smaller in size than their conventional counterparts. The YBCO coated conductor is expected to be the premiere HTS conductor...superconductors (HTS) can enable megawatt-class power systems which are lighter in weight and smaller in size than their conventional counterparts. The...Pinning, Superconducting Machines . PACS: 74.60.G, 74.76.B, 74.25.H, 74.72.B INTRODUCTION A variety of future military systems will require large amounts

  10. YBCO Coated Conductors with Reduced AC Losses

    DTIC Science & Technology

    2008-01-30

    application such as turbo- generators and gyrotron magnets . The major reason is the enhanced in-field performance at 50-65 K and the proven...transformers, current limiters and the stators of rotating equipment. Low AC-loss in 2G HTS requires wire components with low magnetism , and an YBCO...layer with low transport and low hysteretic losses in an alternating magnetic field. The latter loss type requires a suitable filamentization technique

  11. High speed low damage grinding of advanced ceramics - Phase II Final Report

    SciTech Connect

    Kovach, J.A.; Malkin, S.

    2000-02-01

    In the manufacture of structural ceramic components, grinding costs can comprise up to 80% of the entire manufacturing cost. As a result, one of the most challenging tasks faced by manufacturing process engineers is the development of a ceramic finishing process to maximize part throughput while minimizing costs and associated scrap levels. The efforts summarized in this report represent the second phase of a program whose overall objective was to develop a single-step, roughing-finishing process suitable for producing high-quality silicon nitride parts at high material removal rates and at substantially lower cost than traditional, multi-stage grinding processes. More specifically, this report provides a technical overview of High-Speed, Low-Damage (HSLD) ceramic grinding which employs elevated wheel speeds to achieve the small grain depths of cut necessary for low-damage grinding while operating at relatively high material removal rates. The study employed the combined use of laboratory grinding tests, mathematical grinding models, and characterization of the resultant surface condition. A single-step, roughing-finishing process operating at high removal rates was developed and demonstrated.

  12. Fabrication of high critical current density superconducting tapes by epitaxial deposition of YBCO thick films on biaxially textured metal substrates

    SciTech Connect

    Goyal, A.; Norton, D.P.; Paranthaman, M.

    1996-12-31

    High critical current density YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) tapes were fabricated by epitaxial deposition on rolling- assisted-biaxially-textured-substrates (RABiTS). The RABiTS technique uses well established, industrially scaleable, thermomechanical processes to impart a strong biaxial texture to a base metal. This is followed by vapor deposition of epitaxial buffer layers to yield chemically and structurally compatible surfaces. Epitaxial YBCO films grown on such substrates have critical current densities approaching 10{sup 6} A/cm{sup 2} at 77K in zero field and have field dependences similar to epitaxial films on single crystal ceramic substrates. Deposited conductors made using this technique offer a potential route for fabricating long lengths of high J{sub c} wire capable of carrying high currents in high magnetic fields and at elevated temperatures.

  13. Static Test for a Gravitational Force Coupled to Type 2 YBCO Superconductors

    NASA Technical Reports Server (NTRS)

    Li, Ning; Noever, David; Robertson, Tony; Koczor, Ron; Brantley, Whitt

    1997-01-01

    As a Bose condensate, superconductors provide novel conditions for revisiting previously proposed couplings between electromagnetism and gravity. Strong variations in Cooper pair density, large conductivity and low magnetic permeability define superconductive and degenerate condensates without the traditional density limits imposed by the Fermi energy (approx. 10(exp -6) g cc. Recent experiments have reported anomalous weight loss for a test mass suspended above a rotating type II, YBCO superconductor, with the percentage change (0.05 - 2.1 %) independent of the test mass' chemical composition and diamagnetic properties. A variation of 5 parts per 10' was reported above a stationary (non-rotating) superconductor. In experiments using a sensitive gravimeter, bulk YBCO superconductors were stably levitated in a DC magnetic field. Changes in acceleration were measured to be less than 2 parts in 108 of the normal gravitational acceleration. This result puts new limits on the strength and range of the proposed coupling between static superconductors and gravity.

  14. Mode I and Mode II Interlaminar Crack Growth Resistances of Ceramic Matrix Composites at Ambient Temperature

    DTIC Science & Technology

    2007-03-02

    Sci. Proc., 25[4] 71-78 (2004). 9. L. P. Zawada , “Longitudinal and Transthickness Tensile Behavior of Several Oxide/Oxide Composites,” Ceram. Eng...Unidirectional C-C Composite,” J. Nucl. Mater., 230 226-232 (1996). 11. S. Mall, R. P. Vozzola, and L. Zawada , “Characterization of Fracture in Fiber...Behavior of a Unidirectional C-C Composite,” J. Nucl. Mater., 230 226-232 (1996). 34. L. P. Zawada , “Longitudinal and Transthickness Tensile Behavior

  15. Comparative assessment of marginal accuracy of grade II titanium and Ni–Cr alloy before and after ceramic firing: An in vitro study

    PubMed Central

    Patil, Abhijit; Singh, Kishan; Sahoo, Sukant; Suvarna, Suraj; Kumar, Prince; Singh, Anupam

    2013-01-01

    Objective: The aims of the study are to assess the marginal accuracy of base metal and titanium alloy casting and to evaluate the effect of repeated ceramic firing on the marginal accuracy of base metal and titanium alloy castings. Materials and Methods: Twenty metal copings were fabricated with each casting material. Specimens were divided into 4 groups of 10 each representing base metal alloys castings without (Group A) and with metal shoulder margin (Group B), titanium castings without (Group C) and with metal shoulder margin (Group D). The measurement of fit of the metal copings was carried out before the ceramic firing at four different points and the same was followed after porcelain build-up. Results: Significant difference was found when Ni–Cr alloy samples were compared with Grade II titanium samples both before and after ceramic firings. The titanium castings with metal shoulder margin showed highest microgap among all the materials tested. Conclusions: Based on the results that were found and within the limitations of the study design, it can be concluded that there is marginal discrepancy in the copings made from Ni–Cr and Grade II titanium. This marginal discrepancy increased after ceramic firing cycles for both Ni–Cr and Grade II titanium. The comparative statistical analysis for copings with metal-collar showed maximum discrepancy for Group D. The comparative statistical analysis for copings without metal-collar showed maximum discrepancy for Group C. PMID:24926205

  16. Fast infrared response of YBCO thin films

    NASA Technical Reports Server (NTRS)

    Ballentine, P. H.; Kadin, A. M.; Donaldson, W. R.; Scofield, J. H.; Bajuk, L.

    1990-01-01

    The response to short infrared pulses of some epitaxial YBCO films prepared by sputter deposition and by electron-beam evaporation is reported. The response is found to be essentially bolometric on the ns timescale, with some indirect hints of nonequilibrium electron transport on the ps scale. Fast switching could be obtained either by biasing the switch close to the critical current or by cooling the film below about 20 K. These results are encouraging for potential application to a high-current optically-triggered opening switch.

  17. Vortex motion in YBCO thin films

    NASA Astrophysics Data System (ADS)

    Shapiro, V.; Verdyan, A.; Lapsker, I.; Azoulay, J.

    1999-09-01

    Hall resistivity measurements as function of temperature in the vicinity of Tc were carried out on a thin films YBCO superconductors. A sign reversal of Hall voltage with external magnetic field applied along c axis have been observed upon crossing Tc. Hall voltage in the mixed state was found to be insensitive to the external magnetic field inversion. These effects are discussed and explained in terms of vortex motion under the influence of Magnus force balanced by large damping force. It is argued that in this model the flux-line velocity has component opposite to the superfluid current direction thus yielding a negative Hall voltage.

  18. Maximum permissible voltage of YBCO coated conductors

    NASA Astrophysics Data System (ADS)

    Wen, J.; Lin, B.; Sheng, J.; Xu, J.; Jin, Z.; Hong, Z.; Wang, D.; Zhou, H.; Shen, X.; Shen, C.

    2014-06-01

    Superconducting fault current limiter (SFCL) could reduce short circuit currents in electrical power system. One of the most important thing in developing SFCL is to find out the maximum permissible voltage of each limiting element. The maximum permissible voltage is defined as the maximum voltage per unit length at which the YBCO coated conductors (CC) do not suffer from critical current (Ic) degradation or burnout. In this research, the time of quenching process is changed and voltage is raised until the Ic degradation or burnout happens. YBCO coated conductors test in the experiment are from American superconductor (AMSC) and Shanghai Jiao Tong University (SJTU). Along with the quenching duration increasing, the maximum permissible voltage of CC decreases. When quenching duration is 100 ms, the maximum permissible of SJTU CC, 12 mm AMSC CC and 4 mm AMSC CC are 0.72 V/cm, 0.52 V/cm and 1.2 V/cm respectively. Based on the results of samples, the whole length of CCs used in the design of a SFCL can be determined.

  19. Remarkable weakness against cleavage stress for YBCO-coated conductors and its effect on the YBCO coil performance

    NASA Astrophysics Data System (ADS)

    Yanagisawa, Y.; Nakagome, H.; Takematsu, T.; Takao, T.; Sato, N.; Takahashi, M.; Maeda, H.

    2011-08-01

    Cleavage strength for an YBCO-coated conductor at 77 K was investigated with a model experiment. The nominal cleavage strength for an YBCO-coated conductor is extremely low, typically 0.5 MPa. This low nominal cleavage strength is due to stress concentration on a small part of the YBCO-coated conductor in cleavage fracture. Debonding by the cleavage stress occurs at the interface between the buffer layer and the Hastelloy substrate. The nominal cleavage strength for a slit edge of the conductor is 2.5-times lower than that for the original edge of the conductor; cracks and micro-peel existing over the slit edge reduce the cleavage strength for the slit edge. Cleavage stress and peel stress should be avoided in coil winding, as they easily delaminate the YBCO-coated conductor, resulting in substantial degradation of coil performance. These problems are especially important for epoxy impregnated YBCO-coated conductor coils. It appears that effect of cleavage stress and peel stress are mostly negligible for paraffin impregnated YBCO-coated conductor coils or dry wound YBCO-coated conductor coils.

  20. Quasiparticle dynamics in YBCO and YBCO/LSMO Using Femtosecond Optical Pulses

    NASA Astrophysics Data System (ADS)

    Lee, J.; Talbayev, D.; Xiong, J.; Zhu, J.; Jia, Q.; Taylor, A. J.; Prasankumar, R. P.

    2012-02-01

    The properties of various complex oxide systems, such as multiferroics, high-Tc superconductors and colossal magnetoresistance manganites, have been extensively studied for the past ˜25 years. In particular, the interplay between superconductivity (SC) and ferromagnetism (FM) is interesting from both academic and applied viewpoints. we have temporally resolved quasiparticle dynamics in multilayered films composed of the high-temperature superconductor YBCO and the ferromagnetic manganite LaSrMnO3 (LSMO) by performing temperature-dependent UOS experiments. In YBCO alone, we observed two distinct decay relaxation channels that have previously been related to the pseudogap and superconducting gaps and can be explained with the phenomenological Rothwarf-Taylor (RT) model. However, the fast sub-picosecond relaxation related to the pseudogap was not observed in our YBCO/LSMO heterostructures, possibly due to the influence of FM order These first UOS experiments on SC/FM heterostructures demonstrate the ability of UOS to quantify the influence of ferromagnetism on superconductivity through time domain measurements.

  1. Processing of YBCO superconductors for improved levitation force

    SciTech Connect

    Balachandran, U.; Zhong, W.

    1993-05-01

    One objective of the ANL superconductor program is to develop improved processing methods for production of YBCO superconductors with higher levitation forces suitable for low-friction, superconductor/permanent-magnet bearings and flywheel-energy-storage applications. From the standpoint of these applications, melt-processed bulk YBCO superconductors are of considerable interest. Levitation force and flux-pinning properties depend on microstructural features of the superconductors. We have added several chemical species to YBCO to alter the microstructure and have used a seeding technique to induce crystallization during melt processing. In this paper, we discuss the effects of various process parameters, additives, and a seeding technique on the properties of melt-processed bulk YBCO samples and compare the results with solid-state-sintered superconductors.

  2. An AFM study of the morphology and local mechanical properties of superconducting YBCO thin films

    NASA Astrophysics Data System (ADS)

    Soifer, Ya. M.; Verdyan, A.; Azoulay, J.; Kazakevich, M.; Rabkin, E.

    2004-02-01

    The morphology of thin superconducting YBCO films deposited on sapphire and on SrTiO 3 was studied with the help of atomic force and scanning electron microscopies. The intrinsic mechanical properties in the flat, particles-free and chemically homogeneous regions of the films were determined with the aid of nanoindenting atomic force microscope. Also the microscopy studies revealed the difference in topography of the films, the nanohardness and Young’s modulus of two films were very close to each other. For the indents shallower than 0.2 of the film thickness the Young’s modulus and hardness of the films on two different substrates converged to the values of 210 and 8.5 GPa, respectively. The possible deformation mechanisms determining the localized deformation of intrinsically brittle ceramic films are discussed.

  3. High Critical Current in Metal Organic Derived YBCO Films

    DTIC Science & Technology

    2010-10-31

    Report 3 BACKGROUND The Second Generation (2G) high temperature superconducting (HTS) YBCO wire is a versatile, potentially transformational...transformers, fault current limiters, superconducting magnetic energy storage, and power transmission lines [ 1 ] require improvement in the performance of 2G...commercialization of 2G superconducting wire. The obvious route to higher Ic is to increase the thickness, t, of the YBa2Cu3O7-x (YBCO) layer

  4. Exfoliated YBCO filaments for second-generation superconducting cable

    NASA Astrophysics Data System (ADS)

    Solovyov, Vyacheslav; Farrell, Paul

    2017-01-01

    The second-generation high temperature superconductor (2G HTS) wire is the most promising conductor for high-field magnets such as accelerator dipoles and compact fusion devices. The key element of the wire is a thin Y1Ba2Cu3O7 (YBCO) layer deposited on a flexible metal substrate. The substrate, which becomes incorporated in the 2G conductor, reduces the electrical and mechanical performance of the wire. This is a process that exfoliates the YBCO layer from the substrate while retaining the critical current density of the superconductor. Ten-centimeter long coupons of exfoliated YBCO layers were manufactured, and detailed structural, electrical, and mechanical characterization were reported. After exfoliation, the YBCO layer was supported by a 75 μm thick stainless steel foil, which makes for a compact, mechanically stronger, and inexpensive conductor. The critical current density of the filaments was measured at both 77 K and 4.2 K. The exfoliated YBCO retained 90% of the original critical current. Similarly, tests in an external magnetic field at 4.2 K confirmed that the pinning strength of the YBCO layer was also retained following exfoliation.

  5. [Exposure to ceramic fibers in the work environment. II. Occupational exposure to dust in plants producing ceramic fiber; fibrogenic effect of the fibers].

    PubMed

    Wojtczak, J; Lao, I; Krajnow, A

    1996-01-01

    The aim of the work was to assess the exposure to dust containing ceramic fibres among workers employed in the plant producing aluminosilicate fibres, and to investigate fibrogenic properties of produced ceramic aluminosilicate fibres (L-1). The studies carried out in the work environment revealed that workers were exposed to dust containing respirable fibres from materials produced (fibres, mats). Mean concentrations of these fibres ranged from 0.07 to 0.37 f/cm3 and they were considerably lower than MAC value (1 f/cm3) proposed for respirable ceramic fibres. Mean total dust concentrations ranged from 0.4 to 2.9 mg/m3, and at two working posts they exceeded the proposed MAC value (2 mg/m3). In animal experiments (Wistar female rats) a single dose (25 mg) of L-1 fibres administered intratracheally induced pathological symptoms in lungs, limited to reactive changes in the form of granuloma with weakly pronounced cytolysis, and mean levels of hydroxyproline in the lungs did not differ significantly from the physiological level. The L-1 fibre was classified in the group of dusts with insignificant fibrogenic effects.

  6. Ceramic (Feldspathic & IPS Empress II) vs. laboratory composite (Gradia) veneers; a comparison between their shear bond strength to enamel; an in vitro study.

    PubMed

    Nikzad, S; Azari, Abbas; Dehgan, S

    2010-07-01

    Patient demand for aesthetic dentistry is steadily growing. Laminates and free metal restorations have evolved in an attempt to overcome the invasiveness nature of full veneer restorations. Although many different materials have been used for making these restorations, there is no single material that fits best for all purposes. Two groups of ceramic material (Feldspathic and IPS Empress II) and one group of laboratory composite (Gradia) discs (10 discs in each group; 4 mm in diameter and 2 mm in thickness) were prepared according to the manufacturer's instruction. The surface of ceramic discs were etched and silanized. In Gradia group, liquid primer was applied on composite surfaces. Thirty freshly extracted sound human molars and premolars were randomly divided into three groups. The enamel surface of each tooth was slightly flattened (0.3 mm) on the buccal or lingual side and then primed and cemented to the prepared discs with the aid of a dental surveyor. The finishing specimens were thermocycled between 5 degrees C and 55 degrees C for 2500 cycles and then prepared for shear bond strength testing. The resulting data were analyzed by one-way anova and Tukey HSD test. The fractured surfaces of each specimen were inspected by means of stereomicroscope and SEM. There is significant difference between the bond strength of materials tested. The mean bond strengths obtained with Feldspathic ceramic, IPS Empress II and Gradia were 33.10 +/- 4.31 MPa, 26.04 +/- 7.61 MPa and 14.42 +/- 5.82 MPa, respectively. The fracture pattern was mainly mixed for ceramic groups. More scientific evidence needed for standardization of bonding protocols.

  7. Coupling Losses and Transverse Resistivity of Multifilament YBCO Coated Superconductors (Postprint)

    DTIC Science & Technology

    2012-02-01

    AFRL-RZ-WP-TP-2012-0125 COUPLING LOSSES AND TRANSVERSE RESISTIVITY OF MULTIFILAMENT YBCO COATED SUPERCONDUCTORS (POSTPRINT) M. Polak, E... YBCO COATED SUPERCONDUCTORS (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62203F 6. AUTHOR(S) M...filamentary YBCO coated conductors. A 10 mm wide YBCO coated conductor was subdivided into 20 filaments by laser ablation. We measured the frequency

  8. Portfolio: Ceramics.

    ERIC Educational Resources Information Center

    Hardy, Jane; And Others

    1982-01-01

    Describes eight art activities using ceramics. Elementary students created ceramic tiles to depict ancient Egyptian and medieval European art, made ceramic cookie stamps, traced bisque plates on sketch paper, constructed clay room-tableaus, and designed clay relief masks. Secondary students pit-fired ceramic pots and designed ceramic Victorian…

  9. In-vitro investigation to evaluate the flexural bond strengths of three commercially available ultra low fusing ceramic systems to Grade II Titanium

    PubMed Central

    Mabrurkar, Vijay; Habbu, Nitin; Hashmi, Sayed Wahhiuddin; Musani, Smita; Joshi, Nikhil

    2013-01-01

    Background: This in-vitro investigation was designed to compare the flexural bond strengths of three commercially available ultra low fusing ceramic systems to Grade II Titanium and evaluate the type of bond failure through Scanning Electron Microscopy (SEM) and Energy Dispersion X ray Spectrum (EDS). Materials & Methods: Sixty patterns of auto polymerizing resin of dimensions 25.1 mm X 3.1mm X 0.6mm each were fabricated from a stainless steel die. Titanium casting for all the samples was done in a Titanium casting machine. Ten samples were allotted to each of three groups randomly. Ceramic build up was done step by step using the manufacturers' instructions. Flexural Bond strength tests for the samples were performed by using a 3-point bending test on a Universal testing machine in compliance with Deutsches Institut für Normung (DIN) 13.927 draft. After the tests were completed, three samples, one from each group were selected randomly for the subsequent Scanning Electronic Microscopy (SEM) studies to characterize the type and morphology of the fracture in representative specimens. Results: The maximum load to fracture the porcelain was recorded for each specimen. All the means of the three groups were compared by one-way Analysis of Variance (ANOVA) and it was found that Group I & Group III had significantly higher bond strength values as compared with the Group II (P< 0.001). All the 10 samples of Group I & III gave bond strength values above the standard values of 25 MPa. There was statistically significant difference in the bond strengths between Group I & Group III (t = 2.76 and P< 0.05), between Group I & II (t = 5.09 and P< 0.001) and between Group II & Group III (t = 13.28 and P< 0.001). SEM studies revealed occurrence of cohesive type fractures in the ceramic body of samples belonging to Groups I & III, while there was adhesive failure at ceramo-metal junction of samples belonging to Group II. EDS Analysis supported the findings of SEM studies

  10. Sealing glass-ceramics with near-linear thermal strain, Part II: Sequence of crystallization and phase stability

    SciTech Connect

    Rodriguez, Mark A.; Griego, James J. M.; Dai, Steve

    2016-08-22

    The sequence of crystallization in a recrystallizable lithium silicate sealing glass-ceramic Li2O–SiO2–Al2O3–K2O–B2O3–P2O5–ZnO was analyzed by in situ high-temperature X-ray diffraction (HTXRD). Glass-ceramic specimens have been subjected to a two-stage heat-treatment schedule, including rapid cooling from sealing temperature to a first hold temperature 650°C, followed by heating to a second hold temperature of 810°C. Notable growth and saturation of Quartz was observed at 650°C (first hold). Cristobalite crystallized at the second hold temperature of 810°C, growing from the residual glass rather than converting from the Quartz. The coexistence of quartz and cristobalite resulted in a glass-ceramic having a near-linear thermal strain, as opposed to the highly nonlinear glass-ceramic where the cristobalite is the dominant silica crystalline phase. HTXRD was also performed to analyze the inversion and phase stability of the two types of fully crystallized glass-ceramics. While the inversion in cristobalite resembles the character of a first-order displacive phase transformation, i.e., step changes in lattice parameters and thermal hysteresis in the transition temperature, the inversion in quartz appears more diffuse and occurs over a much broader temperature range. Furthermore, localized tensile stresses on quartz and possible solid-solution effects have been attributed to the transition behavior of quartz crystals embedded in the glass-ceramics.

  11. Sealing glass-ceramics with near-linear thermal strain, Part II: Sequence of crystallization and phase stability

    DOE PAGES

    Rodriguez, Mark A.; Griego, James J. M.; Dai, Steve

    2016-08-22

    The sequence of crystallization in a recrystallizable lithium silicate sealing glass-ceramic Li2O–SiO2–Al2O3–K2O–B2O3–P2O5–ZnO was analyzed by in situ high-temperature X-ray diffraction (HTXRD). Glass-ceramic specimens have been subjected to a two-stage heat-treatment schedule, including rapid cooling from sealing temperature to a first hold temperature 650°C, followed by heating to a second hold temperature of 810°C. Notable growth and saturation of Quartz was observed at 650°C (first hold). Cristobalite crystallized at the second hold temperature of 810°C, growing from the residual glass rather than converting from the Quartz. The coexistence of quartz and cristobalite resulted in a glass-ceramic having a near-linear thermal strain,more » as opposed to the highly nonlinear glass-ceramic where the cristobalite is the dominant silica crystalline phase. HTXRD was also performed to analyze the inversion and phase stability of the two types of fully crystallized glass-ceramics. While the inversion in cristobalite resembles the character of a first-order displacive phase transformation, i.e., step changes in lattice parameters and thermal hysteresis in the transition temperature, the inversion in quartz appears more diffuse and occurs over a much broader temperature range. Furthermore, localized tensile stresses on quartz and possible solid-solution effects have been attributed to the transition behavior of quartz crystals embedded in the glass-ceramics.« less

  12. Removal of degradation of the performance of an epoxy impregnated YBCO-coated conductor double pancake coil by using a polyimide-electrodeposited YBCO-coated conductor

    NASA Astrophysics Data System (ADS)

    Yanagisawa, Y.; Sato, K.; Piao, R.; Nakagome, H.; Takematsu, T.; Takao, T.; Kamibayashi, H.; Takahashi, M.; Maeda, H.

    2012-06-01

    Degradation of the epoxy impregnated YBCO coil performance is due to tensile radial stress concentration on the outer edge of the conductor during cool down. This stress acts as a cleavage stress and opens the conductor edge, fracturing the YBCO layer. The fracture propagates to another edge of the conductor, resulting in degradation of the coil performance. Degradation of the epoxy impregnated YBCO coil is eliminated, if we use a polyimide-electrodeposited YBCO-coated conductor: tensile radial stress concentration on the outer edge of the conductor is reduced due to plastic deformation of the ductile polyimide. Polyimide electrodeposition onto the YBCO-coated conductor is reliable, uniform, easy to apply, and can be extended to larger YBCO magnets, removing the risk of coil degradation.

  13. Synthesis of nanoscale superconducting YBCO by a novel technique

    NASA Astrophysics Data System (ADS)

    Xu, X. L.; Guo, J. D.; Wang, Y. Z.; Sozzi, A.

    2002-06-01

    A novel technique using citrate pyrolysis was developed to prepare nanoscale superconducting oxide materials. This paper describes the details on synthesizing nanocrystalline YBCO with a Tc of ∼80 K using this method. The morphology and structure of the nanoscale products were characterized by powder X-ray diffraction and scanning electron microscopy. The obtained YBCO grains have a mean particle size of 40-60 nm (for unannealed samples) and 100-150 nm (for the annealed products). The crystalline size was only ∼20 nm. Currently there are attempts at using such fine powder to fabricate longer superconducting tapes, which should induce a technical revolution in the production of superconducting tapes.

  14. Soft nanostructuring of YBCO Josephson junctions by phase separation.

    PubMed

    Gustafsson, D; Pettersson, H; Iandolo, B; Olsson, E; Bauch, T; Lombardi, F

    2010-12-08

    We have developed a new method to fabricate biepitaxial YBa2 Cu3 O7-δ (YBCO) Josephson junctions at the nanoscale, allowing junctions widths down to 100 nm and simultaneously avoiding the typical damage in grain boundary interfaces due to conventional patterning procedures. By using the competition between the superconducting YBCO and the insulating Y2 BaCuO5 phases during film growth, we formed nanometer sized grain boundary junctions in the insulating Y2 BaCuO5 matrix as confirmed by high-resolution transmission electron microscopy. Electrical transport measurements give clear indications that we are close to probing the intrinsic properties of the grain boundaries.

  15. [Raman spectra of YBCO superconductor with hot ultrapressing treatment].

    PubMed

    Yang, Hai-feng; Wei, Le-han; Cao, Xiao-wei

    2002-02-01

    Laser Raman spectra of YBCO oxide superconductor with hot ultrapressing and annealing treatment are reported. In addition to improving physical properties, the spectra data show that the processing can also perfect orthorhombie phase and enhance lattice on orientation trend as well as is good for formation of two dimension CuO2 net. The relation between structure and the superconductivity has been discussed.

  16. Pr Doped YBCO Films Produced by Pulsed Laser Deposition (Postprint)

    DTIC Science & Technology

    2012-02-01

    found that the substituent was dispersed throughout the film and led to an increase in nanoparticles. EXPERIMENT Thin films of (Y1-x, Prx )Ba2Cu3O7-d...were produced by PLD using conditions previously optimized for pure YBCO. PLD targets were prepared with the composition (Y1-x, Prx )Ba2Cu3O7- d

  17. The magnetoresistance of YBCO/BZO composite superconductors

    NASA Astrophysics Data System (ADS)

    Malik, Bilal A.; Asokan, K.; Ganesan, V.; Singh, Durgesh; Malik, Manzoor A.

    2016-12-01

    We study the effect of addition of BaZrO3 (BZO) on normal and superconducting state of YBa2Cu3O7-δ (YBCO). We find that in general both room temperature and residual resistivity increase with the addition of BZO except at low concentration of BZO. The temperature dependence of resistivity in presence of magnetic field also shows less resistivity broadening in composites containing low concentration of BZO below transition temperature (TC). The zero temperature upper critical field (Hc2(0)), estimated by using Werthamer, Helfand and Hohenberg theory and Ginzburg Landau theory, shows an increase by the finite addition of BZO in YBCO. Further, the activation energy (U0) determined from Arrhenius plots and vortex glass transition temperature (Tg) also increase with the limited addition of BZO. Such an enhancement in Hc2(0), Uo and Tg has been attributed to the increase in grain connectivity of YBCO . We conclude that the limited addition of BZO in YBCO significantly improves its superconducting performance in magnetic environment.

  18. High Tc YBCO superconductor deposited on biaxially textured Ni substrate

    DOEpatents

    Budai, John D.; Christen, David K.; Goyal, Amit; He, Qing; Kroeger, Donald M.; Lee, Dominic F.; List, III, Frederick A.; Norton, David P.; Paranthaman, Mariappan; Sales, Brian C.; Specht, Eliot D.

    1999-01-01

    A superconducting article includes a biaxially-textured Ni substrate, and epitaxial buffer layers of Pd (optional), CeO.sub.2 and YSZ, and a top layer of in-plane aligned, c-axis oriented YBCO having a critical current density (J.sub.c) in the range of at least 100,000 A/cm.sup.2 at 77 K.

  19. Structural ceramics

    SciTech Connect

    Wachtman, J.B. Jr.

    1989-01-01

    The present work discusses opportunities for application of structural ceramics in heat engines, industrial-wear parts, prosthetics and bearings; conceptual and detailed design principles for structural ceramics; the processing, consolidation, and properties of members of the SiC family of structural ceramics; and the silicon nitride and sialon families of hot-pressed, sintered, and reaction-bonded, structural ceramics. Also discussed are partially-stabilized zirconia and zirconia-toughened ceramics for structural applications, the processing methods and mechanisms of fiber-reinforcement in ceramic-matrix fiber-reinforced composites, and the tribological properties of structural ceramics.

  20. HTS electrical machines with YBCO bulk and Ag-BSCCO plate-shape HTS elements: recent results and future development

    NASA Astrophysics Data System (ADS)

    Kovalev, L. K.; Ilushin, K. V.; Penkin, V. T.; Kovalev, K. L.; Koneev, S. M.-A.; Modestov, K. A.; Larionoff, S. A.; Gawalek, W.; Oswald, B.

    2001-05-01

    Novel types of electric HTS motors with the rotor containing bulk YBCO elements are presented. Different schematics of hysteresis, reluctance “trapped field” and composed HTS motors are discussed. The two-dimensional mathematical models describing the processes in such types of HTS machines were developed on the basis of the theoretical analysis of the electrodynamic and hysteresis processes in the multi-domain and single-domain YBCO ceramic samples. The test results of the series of these HTS motors with output power 1-20 kW and current frequency 50 and 400 Hz are given. These results show that in the media of liquid nitrogen the specific output power per one weight unit is four to five times better then for conventional electric machines. The design of a new high power HTS motor operating in the liquid nitrogen with output power 200 kW (and more) is discussed. Future applications of new types of HTS motors for airspace and on-land industry and transport systems are discussed.

  1. Sealing glass-ceramics with near linear thermal strain, Part II: Sequence of crystallization and phase stability

    DOE PAGES

    Dai, Steve Xunhu; Rodriguez, Mark A.; Griego, James M.

    2016-06-01

    Here, the sequence of crystallization in a re-crystallizable lithium silicate sealing glass-ceramic Li2O-SiO2-Al2O3-K2O-B2O3-P2O5-ZnO was analyzed by in situ high temperature X-ray diffraction (HTXRD). Glass-ceramic specimens have been subjected to a 2-stage heat treatment schedule, including rapid cooling from sealing temperature to a 1st hold temperature 650 °C, following by heating to a 2nd hold temperature of 810 °C. Notable growth and saturation of Quartz was observed at 650 °C (1st hold).

  2. Sealing glass-ceramics with near linear thermal strain, Part II: Sequence of crystallization and phase stability

    SciTech Connect

    Dai, Steve Xunhu; Rodriguez, Mark A.; Griego, James M.

    2016-06-01

    Here, the sequence of crystallization in a re-crystallizable lithium silicate sealing glass-ceramic Li2O-SiO2-Al2O3-K2O-B2O3-P2O5-ZnO was analyzed by in situ high temperature X-ray diffraction (HTXRD). Glass-ceramic specimens have been subjected to a 2-stage heat treatment schedule, including rapid cooling from sealing temperature to a 1st hold temperature 650 °C, following by heating to a 2nd hold temperature of 810 °C. Notable growth and saturation of Quartz was observed at 650 °C (1st hold).

  3. Equilibrium adsorption isotherm studies of Cu (II) and Co (II) in high concentration aqueous solutions on Ag-TiO2-modified kaolinite ceramic adsorbents

    NASA Astrophysics Data System (ADS)

    Ajenifuja, E.; Ajao, J. A.; Ajayi, E. O. B.

    2016-03-01

    Photocatalytic ceramic adsorbents were prepared from locally sourced kaolinite clay minerals for the removal of copper and cobalt ions from high concentration aqueous solutions. The minerals were treated with mild acid before modification using silver nanoparticles sources and titanium-oxide nanoparticles. Batch adsorption experiment was carried out on the targeted ions and the results were analyzed by Langmuir and Freundlich equation at different concentrations (100-1000 mg/l). As-received raw materials do not exhibit any adsorption capacity. However, the adsorption isotherms for modified kaolinite clay ceramic adsorbents could be fitted well by the Langmuir model for Cu2+ and Co2+ with correlation coefficient (R) of up to 0.99705. The highest and lowest monolayer coverage (q max) were 93.023 and 30.497 mg/g for Cu2+ and Co2+, respectively. The separation factor (R L ) was less than one (<1), indicating that the adsorption of metal ions on modified ceramic adsorbent is favorable. The highest adsorbent adsorption capacity (K f ) and intensity (n) constants obtained from Freundlich model are 14.401 (Cu2+ on KLN-T) and 6.057 (Co2+ on KLN-T).

  4. YBa sub 2 Cu sub (3-x) Co sub x O sub y : A substrate material for YBCO superconductors

    SciTech Connect

    Vienna, J.D.; Balachandran, U.; Poeppel, R.B. ); Cermignani, W.; Taylor, J.A. . Coll. of Ceramics)

    1992-04-01

    The physical properties of the ceramic YBa{sub 2}Cu{sub (3-x)}Co{sub x}O{sub y} have been investigated in order to evaluate its usefulness as a substrate material for YBCO superconductors. YBa{sub 2}Cu{sub (3-x)}Co{sub x}O{sub y} has been found to be thermally and chemically compatible with 123 and displays adequate electrical properties for a substrate material. A material with the nominal composition of YBa{sub 2}Cu{sub 2.2}Co{sub 0.8}O{sub 7} was investigated, extensively. The mechanical properties of this material were found to be poor, e.g., tensile strength was only 60 MPa. A semiconductor-like behavior was observed with a room-temperature resistivity of 70 m{Omega}.cm and a resistivity equal to 4 {times} 10{sup 6} m{Omega}.cm at 77 K.

  5. Theory of the vortex matter transformations in high-Tc superconductor YBCO.

    PubMed

    Li, Dingping; Rosenstein, Baruch

    2003-04-25

    Flux line lattice in type II superconductors undergoes a transition into a "disordered" phase such as vortex liquid or vortex glass, due to thermal fluctuations and random quenched disorder. We quantitatively describe the competition between the thermal fluctuations and the disorder using the Ginzburg-Landau approach. The following T-H phase diagram of YBCO emerges. There are just two distinct thermodynamical phases, the homogeneous and the crystalline one, separated by a single first order transition line. The line, however, makes a wiggle near the experimentally claimed critical point at 12 T. The "critical point" is reinterpreted as a (noncritical) Kauzmann point in which the latent heat vanishes and the line is parallel to the T axis. The magnetization, the entropy, and the specific heat discontinuities at melting compare well with experiments.

  6. A new method to detect the vortex glass phase and its evidence in YBCO.

    PubMed

    Adesso, M G; Polichetti, M; Pace, S

    2008-09-24

    The evidence of the vortex glass phase has been obtained by analysing the nonlinear magnetic response of type-II superconductors. The method introduced here is based on a combined frequency dependence analysis of the real and imaginary part of the 1st and 3rd harmonics of the AC magnetic susceptibility. The analysis has been performed by taking into account both the components and the Cole-Cole plots (i.e. the imaginary part as a function of the real part). Numerical simulations have been used to identify the fingerprints of the magnetic behaviour in the vortex glass phase. These characteristics allowed the vortex glass phase to be distinguished from the other disordered phases, even those showing similar electrical properties. Finally, this method has been successfully applied to detecting the vortex glass phase in an YBCO bulk melt-textured sample.

  7. Homoepitaxial growth of MOD-YBCO thick films on evaporated and MOD templates

    NASA Astrophysics Data System (ADS)

    Tanabe, D.; Yamaguchi, I.; Sohma, M.; Tsukada, K.; Matsui, M.; Kumagai, T.; Manabe, T.

    2011-11-01

    We have prepared metal organic deposition (MOD)-YBCO thick films by repeating the coating-pyrolysis-crystallization procedure onto ∼100-nm-thick evaporated and MOD templates. Surface morphology of the template was found to strongly affect the homoepitaxial growth of MOD-YBCO layers on the template; namely, the epitaxial growth of MOD-YBCO on the evaporated template was much easier than that on the MOD template. A 220-nm-thick epitaxial MOD-YBCO film was successfully prepared on the 100-nm-thick evaporated-YBCO template to obtain a 320-nm-thick YBCO film, which exhibited Jc = 2.44 MA/cm2 and Ic = 78 A/cm. The Ic value has significantly increased from 37 A/cm for the evaporated-template.

  8. Growth of YBCO Thin Films on TiN(001) and CeO2-Coated TiN Surfaces

    DTIC Science & Technology

    2012-02-01

    substrates. Thin CeO2 (~200 nm thick) and YBCO (~300 nm thick) layers were grown on TiN-coated MgO substrates, using pulsed laser deposition. While YBCO ...and YBCO (300 nm thick) layers were grown on TiN-coated MgO substrates, using pulsed laser deposition. While YBCO grown directly on TiN was of poor...grown on the TiN-coated MgO and then an 300 nm thick YBCO layers was subsequently depos- ited. For other samples, YBCO deposition directly on the

  9. Oxidation and Corrosion of Ceramics and Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Opila, Elizabeth J.; Lee, Kang N.

    2000-01-01

    Ceramics and ceramic matrix composites are candidates for numerous applications in high temperature environments with aggressive gases and possible corrosive deposits. There is a growing realization that high temperature oxidation and corrosion issues must be considered. There are many facets to these studies, which have been extensively covered in some recent reviews. The focus of this paper is on current research, over the past two years. In the authors' view, the most important oxidation and corrosion studies have focused on four major areas during this time frame. These are; (I) Oxidation of precursor-based ceramics; (II) Studies of the interphase material in ceramic matrix composites; (III) Water vapor interactions with ceramics, particularly in combustion environments; and (IV) Development of refractory oxide coatings for silicon-based ceramics. In this paper, we shall explore the most current work in each of these areas.

  10. The Integration of YBCO Coated Conductors into Magnets and Rotating Machinery (Postprint)

    DTIC Science & Technology

    2012-02-01

    AFRL-RZ-WP-TP-2012-0119 THE INTEGRATION OF YBCO COATED CONDUCTORS INTO MAGNETS AND ROTATING MACHINERY (POSTPRINT) G.A. Levin and P.N...COVERED (From - To) February 2012 Conference Paper Postprint 01 January 2004 – 01 January 2006 4. TITLE AND SUBTITLE THE INTEGRATION OF YBCO COATED...Keystone, CO (August 29-September 2, 2005) The Integration of YBCO Coated Conductors into Magnets and Rotating Machinery G. A. Levin and P. N. Barnes

  11. Critical Current in YBCO Coated Conductors in the Presence of a Macroscopic Defect (POSTPRINT)

    DTIC Science & Technology

    2010-03-01

    AFRL-RZ-WP-TP-2010-2084 CRITICAL CURRENT IN YBCO COATED CONDUCTORS IN THE PRESENCE OF A MACROSCOPIC DEFECT (POSTPRINT) Milan Polak and...CRITICAL CURRENT IN YBCO COATED CONDUCTORS IN THE PRESENCE OF A MACROSCOPIC DEFECT (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c...display, or disclose the work. 14. ABSTRACT We have studied the effects of localized defects in the YBCO coated conductors on the critical current. The

  12. Pulsed Laser Deposition of YBCO With Yttrium Oxide Buffer Layers (Postprint)

    DTIC Science & Technology

    2012-02-01

    AFRL-RZ-WP-TP-2012-0092 PULSED LASER DEPOSITION OF YBCO WITH YTTRIUM OXIDE BUFFER LAYERS (POSTPRINT) Paul N. Barnes, Timothy J. Haugan...Paper Postprint 01 January 2002 – 01 January 2004 4. TITLE AND SUBTITLE PULSED LASER DEPOSITION OF YBCO WITH YTTRIUM OXIDE BUFFER LAYERS (POSTPRINT...Textured metallic substrate based HTS coated conductors with the YBCO /CeO2/YSZ/CeO2/Ni architecture have already been shown to exhibit high current

  13. In-Situ Approach to Introduce Flux Pinning in YBCO (Postprint)

    DTIC Science & Technology

    2012-02-01

    AFRL-RZ-WP-TP-2012-0118 IN-SITU APPROACH TO INTRODUCE FLUX PINNING IN YBCO (POSTPRINT) T.J. Haugan Mechanical Energy Conversion Branch...Article Postprint 04 April 2005 – 04 April 2007 4. TITLE AND SUBTITLE IN-SITU APPROACH TO INTRODUCE FLUX PINNING IN YBCO (POSTPRINT) 5a. CONTRACT...published as a chapter in Flux Pinning and AC Loss Studies in YBCO Coated Conductors. Work on this effort was completed in 2007. This is the best

  14. Stability and Normal Zone Propagation Speed in YBCO Coated Conductors with Increased Interfacial Resistance (PREPRINT)

    DTIC Science & Technology

    2010-03-01

    AFRL-RZ-WP-TP-2010-2085 STABILITY AND NORMAL ZONE PROPAGATION SPEED IN YBCO COATED CONDUCTORS WITH INCREASED INTERFACIAL RESISTANCE...August 2006 – 25 August 2008 4. TITLE AND SUBTITLE STABILITY AND NORMAL ZONE PROPAGATION SPEED IN YBCO COATED CONDUCTORS WITH INCREASED INTERFACIAL...reproduce, release, perform, display, or disclose the work. 14. ABSTRACT We will discuss how stability and speed of normal zone propagation in YBCO

  15. Influence of oxygen partial pressure and silver additions on microstructure and related properties of YBCO superconductors

    SciTech Connect

    Singh, J.P.; Joo, J.; Guttschow, R.; Poeppel, R.B.

    1992-02-01

    Microstructure has a great influence on the mechanical and superconducting properties of YBCO. Mechanical properties of YBCO can be improved by both modifying the monolithic microstructure and developing composites of YBCO with silver (Ag). When monolithic YBCO was sintered to high densities ({approx} 91%) at a relatively low temperature ({approx} 910{degrees}C) by controlling oxygen partial pressure during sintering, the result was a small-grain microstructure (average grain size {approx} 5 {mu}m) and hence a high strength of 191 {plus_minus} 7 MPa. Addition of Ag as a second phase further improved the strength of YBCO. Composites of YBCO with 10 to 15 vol % Ag has a strength of 225 {plus_minus} 6 MPa and a fracture toughness of 3.3 {plus_minus} 0.2 MPa{radical}m. These improvements are believed to be due to compressive stresses in the YBCO matrix as a result of thermal mismatch between the YBCO and Ag phases. Furthermore, the Ag particles may provide increased resistance to crack propagation by pinning the crack. On the other hand, addition of Ag as a dopant to substitute for Cu sites in YBCO has a profound but nonmonotonic effect on grain microstructure and the resulting critical current density.

  16. Influence of oxygen partial pressure and silver additions on microstructure and related properties of YBCO superconductors

    SciTech Connect

    Singh, J.P.; Joo, J.; Guttschow, R.; Poeppel, R.B.

    1992-02-01

    Microstructure has a great influence on the mechanical and superconducting properties of YBCO. Mechanical properties of YBCO can be improved by both modifying the monolithic microstructure and developing composites of YBCO with silver (Ag). When monolithic YBCO was sintered to high densities ({approx} 91%) at a relatively low temperature ({approx} 910{degrees}C) by controlling oxygen partial pressure during sintering, the result was a small-grain microstructure (average grain size {approx} 5 {mu}m) and hence a high strength of 191 {plus minus} 7 MPa. Addition of Ag as a second phase further improved the strength of YBCO. Composites of YBCO with 10 to 15 vol % Ag has a strength of 225 {plus minus} 6 MPa and a fracture toughness of 3.3 {plus minus} 0.2 MPa{radical}m. These improvements are believed to be due to compressive stresses in the YBCO matrix as a result of thermal mismatch between the YBCO and Ag phases. Furthermore, the Ag particles may provide increased resistance to crack propagation by pinning the crack. On the other hand, addition of Ag as a dopant to substitute for Cu sites in YBCO has a profound but nonmonotonic effect on grain microstructure and the resulting critical current density.

  17. On Ceramics.

    ERIC Educational Resources Information Center

    School Arts, 1982

    1982-01-01

    Presents four ceramics activities for secondary-level art classes. Included are directions for primitive kiln construction and glaze making. Two ceramics design activities are described in which students make bizarrely-shaped lidded jars, feet, and footwear. (AM)

  18. Ceramic Material.

    DTIC Science & Technology

    1990-05-02

    A ceramic material which is (1) ceramics based on monoclinic BaO.Al2O3.2SiO2; (2) ceramics based on monoclinic SrO.Al2O3.2SiO2; or (3) ceramics based on monoclinic solid solution of BaO.Al2O3.2SiO2 and SrO.Al2O3.2SiO2.

  19. YBCO step-edge junctions with high IcRn

    NASA Astrophysics Data System (ADS)

    Mitchell, E. E.; Foley, C. P.

    2010-06-01

    Step-edge junctions represent one type of grain boundary Josephson junction employed in high-temperature superconducting junction technology. To date, the majority of results published in the literature focus on [001]-tilt grain boundary junctions (GBJs) produced using bicrystal substrates. We investigate the step morphology and YBCO (yttrium barium copper oxide) film structure of YBCO-based step-edge junctions on MgO [001] substrates which structurally resemble [100]-tilt junctions. High-resolution electron microscopy reveals a clean GBJ interface of width ~ 1 nm and a single junction at the top edge. The dependence of the transport properties on the MgO step-edge and junction morphology is examined at 4.2 K, to enable direct comparison with results for other junction studies such as [001]-tilt and [100]-tilt junctions and building on previously published 77 K data. MgO step-edge junctions show a slower reduction in critical current density with step angle compared with [001]-tilt junctions. For optimized step parameters, transport measurements revealed large critical current and normal resistance (IcRN) products (~3-5 mV), comparable with the best results obtained in other kinds of [100]-tilt GBJs in YBCO at 4.2 K. Junction-based devices such as SQUIDs (superconducting quantum interference devices) and THz imagers show excellent performance when MgO-based step-edge junctions are used.

  20. Structural Ceramics

    NASA Technical Reports Server (NTRS)

    1986-01-01

    This publication is a compilation of abstracts and slides of papers presented at the NASA Lewis Structural Ceramics Workshop. Collectively, these papers depict the scope of NASA Lewis' structural ceramics program. The technical areas include monolithic SiC and Si3N4 development, ceramic matrix composites, tribology, design methodology, nondestructive evaluation (NDE), fracture mechanics, and corrosion.

  1. Evaluating Superconducting YBCO Film Properties Using X-Ray Photoelectron Spectroscopy (Postprint)

    DTIC Science & Technology

    2012-02-01

    AFRL-RZ-WP-TP-2012-0093 EVALUATING SUPERCONDUCTING YBCO FILM PROPERTIES USING X-RAY PHOTOELECTRON SPECTROSCOPY (POSTPRINT) Paul N. Barnes...2012 Conference Paper Postprint 01 January 2002 – 01 January 2004 4. TITLE AND SUBTITLE EVALUATING SUPERCONDUCTING YBCO FILM PROPERTIES USING X-RAY

  2. High quality uniform YBCO film growth by the metalorganic deposition using trifluoroacetates

    NASA Astrophysics Data System (ADS)

    Wang, S. S.; Zhang, Z. L.; Wang, L.; Gao, L. K.; Liu, J.

    2017-03-01

    A need exists for the large-area superconducting YBa2Cu3O7-x (YBCO) films with high critical current density for microwave communication and/or electric power applications. Trifluoroacetic metalorganic (TFA-MOD) method is a promising low cost technique for large-scale production of YBCO films, because it does not need high vacuum device and is easily applicable to substrates of various shape and size. In this paper, double-sided YBCO films with maximum 2 in diameter were prepared on LaAlO3 substrates by TFA-MOD method. Inductive critical current densitiy Jc, microwave surface resistance Rs, as well as the microstructure were characterized. A newly homemade furnace system was used to epitaxially grown YBCO films, which can improve the uniformity of YBCO film significantly by gas supply and temperature distribution proper design. Results showed that the large area YBCO films were very uniform in microstructure and thickness distribution, an average inductive Jc in excess of 6 MA/cm2 with uniform distribution, and low Rs (10 GHz) below 0.3 mΩ at 77 K were obtained. Andthe film filter may be prepared to work at temperatures lower than 74 K. These results are very close to the highest value of YBCO films made by conventional vacuum method, so we show a very promising route for large-scale production of high quality large-area YBCO superconducting films at a lower cost.

  3. Experimental studies of diffusion welding of YBCO to copper using solder layers

    NASA Astrophysics Data System (ADS)

    Xie, Y.; Ouyang, Z.; Shi, L.; Kuang, Z.; Meng, M.

    2017-02-01

    The welding technology is of great importance in YBCO application. To make better joints, the diffusion welding of YBCO tape to copper has been carried out in a vacuum environment. In consideration of high welding temperature (above 200°C) could do damage to the material performance, a new kind of diffusion welding method with temperature below 200 °C has been developed recently. A new welding appliance which can offer pressure over 35Kg/mm2 and controlled temperature has been designed and built; several YBCO coated conductors joints soldered with different melting points of tins has been tested. The results showed that the diffusion can perfectly connect YBCO to copper as well as stainless steel and resistance of the joint was low, and the YBCO tape could bear 217°C for at least 15mins.

  4. Ceramic joining

    SciTech Connect

    Loehman, R.E.

    1996-04-01

    This paper describes the relation between reactions at ceramic-metal interfaces and the development of strong interfacial bonds in ceramic joining. Studies on a number of systems are described, including silicon nitrides, aluminium nitrides, mullite, and aluminium oxides. Joints can be weakened by stresses such as thermal expansion mismatch. Ceramic joining is used in a variety of applications such as solid oxide fuel cells.

  5. Ceramic Processing

    SciTech Connect

    EWSUK,KEVIN G.

    1999-11-24

    Ceramics represent a unique class of materials that are distinguished from common metals and plastics by their: (1) high hardness, stiffness, and good wear properties (i.e., abrasion resistance); (2) ability to withstand high temperatures (i.e., refractoriness); (3) chemical durability; and (4) electrical properties that allow them to be electrical insulators, semiconductors, or ionic conductors. Ceramics can be broken down into two general categories, traditional and advanced ceramics. Traditional ceramics include common household products such as clay pots, tiles, pipe, and bricks, porcelain china, sinks, and electrical insulators, and thermally insulating refractory bricks for ovens and fireplaces. Advanced ceramics, also referred to as ''high-tech'' ceramics, include products such as spark plug bodies, piston rings, catalyst supports, and water pump seals for automobiles, thermally insulating tiles for the space shuttle, sodium vapor lamp tubes in streetlights, and the capacitors, resistors, transducers, and varistors in the solid-state electronics we use daily. The major differences between traditional and advanced ceramics are in the processing tolerances and cost. Traditional ceramics are manufactured with inexpensive raw materials, are relatively tolerant of minor process deviations, and are relatively inexpensive. Advanced ceramics are typically made with more refined raw materials and processing to optimize a given property or combination of properties (e.g., mechanical, electrical, dielectric, optical, thermal, physical, and/or magnetic) for a given application. Advanced ceramics generally have improved performance and reliability over traditional ceramics, but are typically more expensive. Additionally, advanced ceramics are typically more sensitive to the chemical and physical defects present in the starting raw materials, or those that are introduced during manufacturing.

  6. Ceramic filters

    SciTech Connect

    Holmes, B.L.; Janney, M.A.

    1995-12-31

    Filters were formed from ceramic fibers, organic fibers, and a ceramic bond phase using a papermaking technique. The distribution of particulate ceramic bond phase was determined using a model silicon carbide system. As the ceramic fiber increased in length and diameter the distance between particles decreased. The calculated number of particles per area showed good agreement with the observed value. After firing, the papers were characterized using a biaxial load test. The strength of papers was proportional to the amount of bond phase included in the paper. All samples exhibited strain-tolerant behavior.

  7. YBCO superconducting ring resonators at millimeter-wave frequencies

    NASA Technical Reports Server (NTRS)

    Chorey, Christopher M.; Kong, Keon-Shik; Bhasin, Kul B.; Warner, J. D.; Itoh, Tatsuo

    1991-01-01

    Microstrip ring resonators operating at 35 GHz were fabricated from laser ablated YBCO films deposited on lanthanum aluminate substrates. They were measured over a range of temperatures and their performances compared to identical resonators made of evaporated gold. Below 60 Kelvin the superconducting strip performed better than the gold, reaching an unloaded Q approximately 1.5 times that of gold at 25 K. A shift in the resonant frequency follows the form predicted by the London equations. The Phenomenological Loss Equivalence Method is applied to the ring resonator and the theoretically calculated Q values are compared to the experimental results.

  8. Quench propagation studies using a small bifilar YBCO coil

    SciTech Connect

    Shiroyanagi, Y.; Sampson, W. B.; Ghosh, Arup

    2012-01-01

    Quench propagation was studied in a small bifilar coil wound from YBCO tape. Measurements were made at 77 K in self-field and at 4.2 K with an applied field. The velocity of quench propagation at 4.2 K was observed to be about an order of magnitude faster than at 77 K both in the longitudinal and transverse directions. During the course of this experiment the conductor damage limit characterized by ∫I2dt was also estimated. Details of the experiment and results are presented in this paper

  9. Microstructure and levitation properties of floating zone melted YBCO samples

    SciTech Connect

    Bashkirov, Yu.A.; Fleishman, L.S.; Vdovin, A.B.; Zubritsky, I.A.; Smirnov, V.V.; Vinogradov, A.V.

    1994-07-01

    Radiation zone melting has been used to produce texture in sintered YBCO cylindrical samples. Microstructural analysis by electron microscopy and pole figure measurements reveals that the production process gives rise to a preferential orientation within large domains. D.C. transport measurements show that changes in alignment orientation can result in the inability to carry a transport current. Both a.c. magnetic field shielding and levitation properties are substantially improved by the floating zone melting, the levitation force being increased with the texture domain size growth.

  10. Fabrication and properties of YBa2Cu3O7- x ceramics at different sintering temperatures

    NASA Astrophysics Data System (ADS)

    Prayoonphokkharat, Poom; Jiansirisomboon, Sukanda; Watcharapasorn, Anucha

    2013-07-01

    The influence of sintering temperatures on the fabrication of YBCO ceramics under normal air atmosphere was investigated in this study. YBCO ceramics were prepared by mixing starting compounds of Y2O3, BaCO3 and CuO powders, which were calcined at 850°C for 12 h. The powder was pelletized and sintered at different temperatures, from 930°C-1050°C, for 12 h. Phase identification was carried out by x-ray diffraction (XRD) technique. Scanning electron microscopy (SEM) with energy dispersive x-ray analysis (EDS) was used to study microstructure and chemical composition. In addition, density, Vickers hardness properties, the change of resistance and dielectric properties with temperature above T c were investigated. It was found that, at 950°C-1000°C, high-purity YBCO ceramic could be obtained. Outside this temperature range, either impurity phases were present or melting occurred. SEM images showed that grain size, which ranged from 1.5-2.5 µm, and hardness were related to density and liquid phase present in the sample. Furthermore, the sintering temperature affected oxygen content which, in turn, determined the conductive or semi-conductive behavior observed by electrical property measurement.

  11. Thermal stability of NdBCO/YBCO/MgO thin film seeds

    NASA Astrophysics Data System (ADS)

    Volochová, D.; Kavečanský, V.; Antal, V.; Diko, P.; Yao, X.

    2016-04-01

    Thermal stability of the Nd1+x Ba2-x Cu3O7-δ (Nd-123 or NdBCO) thin films deposited on MgO substrate, with YBa2Cu3O7-δ (Y-123 or YBCO) buffer layer (NdBCO/YBCO/MgO thin film), has been experimentally studied in order to determine the optimal film thickness acting as seed for bulk YBCO growth. YBCO bulk superconductors with Y2BaCuO5 (Y-211) and CeO2 addition were prepared by the top seeded melt growth process in a chamber furnace using NdBCO/YBCO/MgO thin film seeds of different thicknesses (200-700 nm with 20 nm YBCO buffer layer) and different maximum temperatures, T max. The maximum temperatures varied in the range of 1040 °C-1125 °C. The highest thermal stability 1118 °C was observed in the case of NdBCO/YBCO/MgO thin film of 300 nm thickness. These results are corroborated with differential scanning calorimetry and high temperature x-ray diffraction measurements, as well as microstructure observations.

  12. YSZ buffer layers and YBCO superconducting tapes with enhanced biaxial alignment and properties

    NASA Astrophysics Data System (ADS)

    Savvides, N.; Gnanarajan, S.

    2003-05-01

    Commercial applications of YBa 2Cu 3O 7 (YBCO) superconducting cables require viable and scalable manufacturing processes. We have investigated the evolution of the biaxial alignment of yttria-stabilized zirconia (YSZ) buffer layers with increasing film thickness (50-900 nm) and report on a method of fabricating highly aligned YBCO tapes using a thin epitaxial YSZ buffer layer as template. The method employs magnetron and ion beam assisted deposition (IBAD) techniques followed by epitaxial growth to produce the buffer architectures IBAD-YSZ and epi-YSZ/IBAD-YSZ onto optically polished hastelloy metal substrates. Subsequent in situ deposition of YBCO films is used to determine the biaxial alignment at the surface of the buffer architecture, and to show that 100-200 nm thick epi-YSZ layers suffice to yield YBCO tapes that have enhanced biaxial alignment (Δ φ=9-10°) and high critical current densities: J c(77 K)=(1-2)×10 6 A cm -2 and J c(5 K,1 T)=8×10 6 A cm -2. Atomic force microscopy of the surface microstructure of the YSZ buffer layers and YBCO films reveals some grain coarsening in the epi-YSZ layers compared to the IBAD-YSZ layers while the YBCO tapes show significant outgrowths (∼200 nm) and large grains (800-1200 nm) that are similar to high- Jc YBCO films grown on single crystal MgO(1 0 0) substrates.

  13. Thin YBCO films on ? (001) substrates grown by injection MOCVD

    NASA Astrophysics Data System (ADS)

    Abrutis, A.; Sénateur, J. P.; Weiss, F.; Kubilius, V.; Bigelyte, V.; Saltyte, Z.; Vengalis, B.; Jukna, A.

    1997-12-01

    YBCO thin (about 0953-2048/10/12/021/img10) films were deposited at 0953-2048/10/12/021/img11 on 0953-2048/10/12/021/img12 (001) by single-source injection CVD. Precisely controlled microamounts of organometallic 0953-2048/10/12/021/img13-diketonates dissolved in an organic solvent were injected sequentially into the evaporator by means of a computer-driven injector and the resultant vapour was transported into the deposition zone. The influence of the vapour phase composition on films' properties was investigated. A mixture of 0953-2048/10/12/021/img14 and 0953-2048/10/12/021/img15-oriented YBCO crystallites exists in all deposited films and its ratio depends on the vapour phase composition. For both a and c perpendicular crystallites only 0953-2048/10/12/021/img16 in-plane orientation with respect to substrate axes was found. Bidirectional twinning was established in the crystallites of both types. 0953-2048/10/12/021/img17 of the films (about 90 K) was almost independent of the vapour phase composition in the studied range. However, the critical current density 0953-2048/10/12/021/img18 depended clearly on the vapour phase composition in relation to the 0953-2048/10/12/021/img19 ratio variation. 0953-2048/10/12/021/img18 of the films varied in the range 0953-2048/10/12/021/img21.

  14. A YBCO RF-SQUID magnetometer and its applications

    NASA Technical Reports Server (NTRS)

    Luwei, Zhou; Jingwu, Qiu; Xienfeng, Zhang; Zhiming, Tank; Yongjia, Qian

    1990-01-01

    An applicable RF-superconducting quantum interference detector (SQUID) magnetometer was made using a bulk sintered yttrium barium copper oxide (YBCO). The temperature range of the magnetometer is 77 to 300 K and the field range 0 to 0.1T. At 77 K, the equivalent flux noise of the SQUID is 5 x 10 to minus 4 power theta sub o/square root of Hz at the frequency range of 20 to 200 Hz. The experiments show that the SQUID noise at low-frequency end is mainly from 1/f noise. A coil test shows that the magnetic moment sensitivity delta m is 10 to the minus 6th power emu. The RF-SQUID is shielded in a YBCO cylinder with a shielding ability B sub in/B sub ex of about 10 to the minus 6th power when external dc magnetic field is about a few Oe. The magnetometer is successfully used in characterizing superconducting thin films.

  15. In-situ sputtering of YBCO films for microwave applications

    NASA Technical Reports Server (NTRS)

    Ballentine, P. H.; Kadin, A. M.; Mallory, D. S.

    1991-01-01

    RF magnetron sputtering from a single YBCO target onto a heated substrate (700 C) was used to obtain c-axis-oriented 1-2-3 films that are superconducting without a subsequent annealing or oxygenation step, with Tc(R = 0) as high as 88 K on MgO and LaAlO3 substrates. This process uses an 8-in-diameter target in the sputter-up configuration, with a central grounded shield to eliminate negative ion bombardment. It can reproducibly and uniformly cover substrates as large as 3-in across at rates exceeding 1 A/s. Maintaining film composition very close to stoichiometry is essential for obtaining films with good superconducting properties and surface morphology. Optimum films have critical currents of 1 MA/sq cm at 77 K. Measurements of microwave surface resistance based on a stripline resonator indicate low surface resistance for unpatterned YBCO ground planes, but excess loss and a strong power dependence in a patterned center strip.

  16. Bipolar electrical coil based on YBCO bulks: initial tests

    NASA Astrophysics Data System (ADS)

    Alvarez, A.; Suárez, P.; Ceballos, J. M.; Pérez, B.; Werfel, F.; Floegel-Delor, U.

    2008-02-01

    In the field of the application of HTS in electrical motors, most prototypes are made using superconducting coils based on tape and located in the position where copper coils work in a similar conventional motor. Other prototypes use superconducting bulks (usually disk-shaped) in those positions where normal magnets should work in similar conventional motors. But it is very unusual to find designs using electrical coils based on bulks. This is a challenge whose main problem is the difficulty in machining the superconductor bulks to get the proper shape because of the impossibility of bending the material to wind coils. The design of a bipolar single-turn coil made from a superconducting YBCO disk was proposed by the group of Electrical Application of Superconductors, at the University of Extremadura, several years ago to be an element for the design of a modular two-phase inductor for an air core axial-flux motor. The shape of each coil looks like an 'S'. When a current flows through the circuit, two opposite magnetic fields appear in the upper and lower halves of the piece. Until now, attempts to get a good superconducting circuit by cutting a YBCO disk into the required shape have failed because of cracks appearing in the crystal during the process. Last year, our group at the University of Extremadura began to work with ATZ GmbH who have improved the machining process and made the coils. In this paper we present the coil and the first tests carried out.

  17. Time-frequency Analyses of AE Signals in YBCO Superconductors

    NASA Astrophysics Data System (ADS)

    Nanato, N.; Takemoto, N.

    AE (Acoustic Emission) measurements are well known methods to detect mechanical signals from superconducting coil The mechanical signals could be generated by micro cracks of epoxy resins, the motion of superconductors and the thermal expansion of superconductors, which were generated before and/or after a quench. We have presented a time-frequency visualization of AE signals as a method to detect the quench. We can detect very small AE signals regardless of lectromagnetic noises and can find the time of the AE occurrence and the frequency bands of AE signals by using this method. Recently it has been presented that YBCO superconductors are delaminated and degraded by a transverse tensile stress. The delamination is accompanied with AE signals. Also, it is known that amplitudes and frequency bands of AE signals vary with causes of AE occurrence. In this paper, we present time-frequency analyses of AE signa s caused by the delamination of a YBCO superconductor and the micro of epoxy resins.

  18. Colloidal chemical synthesis and preparation of ceramics with employment of nitrates

    NASA Astrophysics Data System (ADS)

    Fotiev, V. A.

    1991-12-01

    In the present work the theoretical foundation of new sol-gel technology from hydrothermalpeptiration sols, gels, products of spray drying of nitrate solution for obtaining powders for YBCO ceramic and moulding samples are developed. Other studies were carrid out on mechanochemical treatment mixtures of Y 2O 3, Ba(OH) 2, BaO 2, CuO based on aqueus and alcocholic suspenseous leading to binder colloid-chemical constituents formation in the system. After thermal treatment the textured HTSC ceramic has Tc= 91-93 K, Tc < 1.5 K, 1c∼10 4 A/sm 2.

  19. Preparation and characterization of YBCO coating on metallic RABiT substrates by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Gonal, M. R.; Prajapat, C. L.; Igalwar, P. S.; Maji, B. C.; Singh, M. R.; Krishnan, M.

    2016-05-01

    Superconducting YBCO films are coated on metallic Rolling Assisted Bi-axially Textured Substrates (RABiTS) Ni-5wt % W (NiW) (002) substrate using pulsed laser deposition (PLD) system. Targets of YBa2Cu3O7-δ (YBCO) and buffer layers of Ceria and 8 mole % Yttria Stabilized Zirconia (YSZ) of high density are synthesized. At each stage of deposition coatings are characterized by XRD. Transport studies show superconducting nature of YBCO only when two successive buffer layers of YSZ and CeO2 are used.

  20. In Situ Creation of Nanoparticles from YBCO by Pulsed Laser Deposition (Postprint)

    DTIC Science & Technology

    2012-02-01

    entailed pulsed laser deposition (PLD) of YBCO at a high background pressure of 5 Torr O2. The sizes of the nanoparticles range from ~3 to 5 nm and...pulsed laser deposition (PLD) of YBCO at a high background pressure of 5 Torr O2. The sizes of the nanoparticles range from 3 to 5 nm and are typical...are extremely small pieces of matter that have dimensions on the order of a few nm . It may well be possible to use nanoparti- cles of YBCO itself as

  1. Flux Pinning Effects of Y2O3 Nanoparticulate Dispersions in Multilayered YBCO Thin Films

    DTIC Science & Technology

    2012-02-01

    substrates with a Y2O3 nanoparticulate pseudo-layer thickness ranging from 0.2 to 1.4 nm , and YBCO layer thickness varying from 7 to 50 nm . Scanning...with a Y2O3 nanoparticulate pseudo-layer thickness ranging from 0.2 to 1.4 nm , and YBCO layer thickness varying from 7 to 50 nm . Scanning electron...2.0 nm [3,4] compared to about 0.7 nm for Y2O3.4. Conclusion The use of Y2O3 nanoparticulates showed potential as flux pinning centers in YBCO thin

  2. Grain morphology of YBCO coated superconductors prepared by spin process on Ni substrate

    NASA Astrophysics Data System (ADS)

    Liu, C. F.; Du, S. J.; Yan, G.; Xi, W.; Wu, X.; Pang, Y.; Wang, F. Y.; Liu, X. H.; Feng, Y.; Zhang, P. X.; Wu, X. Z.; Zhou, L.

    2003-04-01

    The YBCO thick films with c-axis preferred orientation were prepared by spin and printing processes on Ni substrates (including cold rolling Ni, cube textured Ni, and cube textured Ni+ self-oxided NiO ). The results show that the chrysanthemum (or spherulite) and polygon morphology grains dominate the microstructure of YBCO films. The chrysanthemum size is about 0.2-0.5 mm range, some reaches 1 mm, and polygon grains normally are placed in the center of the chrysanthemum grains. No chrysanthemum grains appear in the thick films prepared on the substrate with Ag or YBCO intermediate layers.

  3. High performance YBCO films. Report for 25 February-25 May 1994

    SciTech Connect

    Denlinger, E.J.

    1994-05-25

    A Bi2O3-based glass composition was found suitable for use under typical YBCO deposition conditions, which is in a vacuum under partial oxygen pressure at about 750 deg C. It was experimently determined that a Ag capping layer thickness of about 5 microns is needed for use with this glass. This Ag thickness will prevent any degradation in the silver layer's conducting properties due to Ag/glass interaction during the glass firing operation at 640 deg C. Lanthanum aluminate samples with YBCO topped with a thin layer of strontium titanate (STO) were prepared by Neocera and had excellent YBCO surface resistance properties as measured with a dielectric resonator test system. These samples will be used to test the compatibility of the YBCO with the silver capping layer deposited over the STO.

  4. YBa{sub 2}Cu{sub (3-x)}Co{sub x}O{sub y}: A substrate material for YBCO superconductors

    SciTech Connect

    Vienna, J.D.; Balachandran, U.; Poeppel, R.B.; Cermignani, W.; Taylor, J.A.

    1992-04-01

    The physical properties of the ceramic YBa{sub 2}Cu{sub (3-x)}Co{sub x}O{sub y} have been investigated in order to evaluate its usefulness as a substrate material for YBCO superconductors. YBa{sub 2}Cu{sub (3-x)}Co{sub x}O{sub y} has been found to be thermally and chemically compatible with 123 and displays adequate electrical properties for a substrate material. A material with the nominal composition of YBa{sub 2}Cu{sub 2.2}Co{sub 0.8}O{sub 7} was investigated, extensively. The mechanical properties of this material were found to be poor, e.g., tensile strength was only 60 MPa. A semiconductor-like behavior was observed with a room-temperature resistivity of 70 m{Omega}.cm and a resistivity equal to 4 {times} 10{sup 6} m{Omega}.cm at 77 K.

  5. Magnetic coupling by using levitation characteristics of YBCO superconductors

    NASA Astrophysics Data System (ADS)

    Ishigaki, H.; Ito, H.; Itoh, M.; Hida, A.; Takahata, R.

    1993-03-01

    A mechanical system which uses high lateral restoring forces of high-Tc materials as the driving force for a magnetic coupling is proposed. As the basic study of the superconducting magnetic coupling, the relationship between the lateral restoring force and levitation force, transmitted torque characteristics as a function of a twisting angle and clearance, and damping characteristics of the coupling were examined. Superiorities of the coupling such as high damping coefficients and high stability against time and twisting angle were revealed. A magnetic force sensor system was used to evaluate the superconducting characteristics of materials, and nonuniform distribution of repulsive force was observed for the YBCO pellet fabricated by the melt-powder-melt-growth process. The improvement of the homogeneity was achieved by compensating for the composition rate which had changed during the quenching process.

  6. Correlation of AC Loss Data from Magnetic Susceptibility Measurements with YBCO Film Quality (Postprint)

    DTIC Science & Technology

    2012-02-01

    excimer laser operating at the KrF, 248 nm , wavelength. Substrates included LaAlO3 ( 100 ) and SrTiO3 ( 100 ) single crystal substrates as well as buffered...AFRL-RZ-WP-TP-2012-0100 CORRELATION OF AC LOSS DATA FROM MAGNETIC SUSCEPTIBILITY MEASUREMENTS WITH YBCO FILM QUALITY (POSTPRINT) Paul N...CORRELATION OF AC LOSS DATA FROM MAGNETIC SUSCEPTIBILITY MEASUREMENTS WITH YBCO FILM QUALITY (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT

  7. On-line characterization of YBCO coated conductors using Raman spectroscopy methods.

    SciTech Connect

    Maroni, V. A.; Reeves, J. L.; Schwab, G.; Chemical Engineering; SuperPower, Inc.

    2007-04-01

    The use of Raman spectroscopy for on-line monitoring of the production of superconducting YBa2Cu3O6+X (YBCO) thin films on long-length metal tapes coated with textured buffer layers is reported for the first time. A methodology is described for obtaining Raman spectra of YBCO on moving tape exiting a metal-organic-chemical-vapor-deposition (MOCVD) enclosure. After baseline correction, the spectra recorded in this way show the expected phonons of the specific YBCO crystal orientation required for high supercurrent transport, as well as phonons of non-superconducting second-phase impurities when present. It is also possible to distinguish YBCO films that are properly textured from films having domains of misoriented YBCO grains. An investigation of the need for focus control on moving tape indicated that focusing of the laser on the surface of the highly reflective YBCO films exiting the MOCVD enclosure tends to produce aberrant photon bursts that swamp the Raman spectrum. These photon bursts are very likely a consequence of optical speckle effects induced by a combination of surface roughness, crystallographic texture, and/or local strain within the small grain microstructure of the YBCO film. Maintaining a slightly out-of-focus condition provides the best signal-to-noise ratio in terms of the obtained Raman spectra. In addition to examining moving tape at the post-MOCVD stage, Raman spectra of the film surface can also be recorded after the oxygen anneal performed to bring the YBCO to the optimum superconducting state. Consideration is given to data processing methods that could be adapted to the on-line Raman spectra to allow the tagging of out-of-specification tape segments and, at a more advanced level, feedback control to the MOCVD process.

  8. Voltage-ampere characteristics of YBCO coated conductor under inhomogeneous oscillating magnetic field

    NASA Astrophysics Data System (ADS)

    Geng, J.; Shen, B.; Li, C.; Zhang, H.; Matsuda, K.; Li, J.; Zhang, X.; Coombs, T. A.

    2016-06-01

    Direct current carrying type II superconductors present a dynamic resistance when subjected to an oscillating magnetic field perpendicular to the current direction. If a superconductor is under a homogeneous field with high magnitude, the dynamic resistance value is nearly independent of transport current. Hoffmann and coworkers [Hoffmann et al., IEEE Trans. Appl. Supercond. 21, 1628 (2011)] discovered, however, flux pumping effect when a superconducting tape is under an inhomogeneous field orthogonal to the tape surface generated by rotating magnets. Following their work, we report the whole Voltage-Ampere (V-I) curves of an YBCO coated conductor under permanent magnets rotating with different frequencies and directions. We discovered that the two curves under opposite rotating directions differ from each other constantly when the transport current is less than the critical current, whereas the difference gradually reduces after the transport current exceeds the critical value. We also find that for different field frequencies, the difference between the two curves decreases faster with lower field frequency. The result indicates that the transport loss is dependent on the relative direction of the transport current and field travelling, which is distinct from traditional dynamic resistance model. The work may be instructive for the design of superconducting motors.

  9. Ideal charge-density-wave order in the high-field state of superconducting YBCO.

    PubMed

    Jang, H; Lee, W-S; Nojiri, H; Matsuzawa, S; Yasumura, H; Nie, L; Maharaj, A V; Gerber, S; Liu, Y-J; Mehta, A; Bonn, D A; Liang, R; Hardy, W N; Burns, C A; Islam, Z; Song, S; Hastings, J; Devereaux, T P; Shen, Z-X; Kivelson, S A; Kao, C-C; Zhu, D; Lee, J-S

    2016-12-20

    The existence of charge-density-wave (CDW) correlations in cuprate superconductors has now been established. However, the nature of the CDW ground state has remained uncertain because disorder and the presence of superconductivity typically limit the CDW correlation lengths to only a dozen unit cells or less. Here we explore the field-induced 3D CDW correlations in extremely pure detwinned crystals of YBa2Cu3O2 (YBCO) ortho-II and ortho-VIII at magnetic fields in excess of the resistive upper critical field ([Formula: see text]) where superconductivity is heavily suppressed. We observe that the 3D CDW is unidirectional and possesses a long in-plane correlation length as well as significant correlations between neighboring CuO2 planes. It is significant that we observe only a single sharply defined transition at a critical field proportional to [Formula: see text], given that the field range used in this investigation overlaps with other high-field experiments including quantum oscillation measurements. The correlation volume is at least two to three orders of magnitude larger than that of the zero-field CDW. This is by far the largest CDW correlation volume observed in any cuprate crystal and so is presumably representative of the high-field ground state of an "ideal" disorder-free cuprate.

  10. Ideal charge-density-wave order in the high-field state of superconducting YBCO

    DOE PAGES

    Jang, H.; Lee, W. -S.; Nojiri, H.; ...

    2016-12-05

    Here, the existence of charge-density-wave (CDW) correlations in cuprate superconductors has now been established. However, the nature of the CDW ground state has remained uncertain because disorder and the presence of superconductivity typically limit the CDW correlation lengths to only a dozen unit cells or less. Here we explore the field-induced 3D CDW correlations in extremely pure detwinned crystals of YBa2Cu3O2 (YBCO) ortho-II and ortho-VIII at magnetic fields in excess of the resistive upper critical field (Hc2) where superconductivity is heavily suppressed. We observe that the 3D CDW is unidirectional and possesses a long in-plane correlation length as well asmore » significant correlations between neighboring CuO2 planes. It is significant that we observe only a single sharply defined transition at a critical field proportional to Hc2, given that the field range used in this investigation overlaps with other high-field experiments including quantum oscillation measurements. The correlation volume is at least two to three orders of magnitude larger than that of the zero-field CDW. This is by far the largest CDW correlation volume observed in any cuprate crystal and so is presumably representative of the high-field ground state of an “ideal” disorder-free cuprate.« less

  11. Ideal charge-density-wave order in the high-field state of superconducting YBCO

    SciTech Connect

    Jang, H.; Lee, W. -S.; Nojiri, H.; Matsuzawa, S.; Yasumura, H.; Nie, L.; Maharaj, A. V.; Gerber, S.; Liu, Y. -J.; Mehta, A.; Bonn, D. A.; Liang, R.; Hardy, W. N.; Burns, C. A.; Islam, Z.; Song, S.; Hastings, J.; Devereaux, T. P.; Shen, Z. -X.; Kivelson, S. A.; Kao, C. -C.; Zhu, D.; Lee, J. -S.

    2016-12-05

    Here, the existence of charge-density-wave (CDW) correlations in cuprate superconductors has now been established. However, the nature of the CDW ground state has remained uncertain because disorder and the presence of superconductivity typically limit the CDW correlation lengths to only a dozen unit cells or less. Here we explore the field-induced 3D CDW correlations in extremely pure detwinned crystals of YBa2Cu3O2 (YBCO) ortho-II and ortho-VIII at magnetic fields in excess of the resistive upper critical field (Hc2) where superconductivity is heavily suppressed. We observe that the 3D CDW is unidirectional and possesses a long in-plane correlation length as well as significant correlations between neighboring CuO2 planes. It is significant that we observe only a single sharply defined transition at a critical field proportional to Hc2, given that the field range used in this investigation overlaps with other high-field experiments including quantum oscillation measurements. The correlation volume is at least two to three orders of magnitude larger than that of the zero-field CDW. This is by far the largest CDW correlation volume observed in any cuprate crystal and so is presumably representative of the high-field ground state of an “ideal” disorder-free cuprate.

  12. Ideal charge-density-wave order in the high-field state of superconducting YBCO

    PubMed Central

    Jang, H.; Lee, W.-S.; Nojiri, H.; Matsuzawa, S.; Yasumura, H.; Nie, L.; Maharaj, A. V.; Gerber, S.; Liu, Y.-J.; Mehta, A.; Bonn, D. A.; Liang, R.; Hardy, W. N.; Burns, C. A.; Islam, Z.; Song, S.; Hastings, J.; Devereaux, T. P.; Shen, Z.-X.; Kivelson, S. A.; Kao, C.-C.; Zhu, D.; Lee, J.-S.

    2016-01-01

    The existence of charge-density-wave (CDW) correlations in cuprate superconductors has now been established. However, the nature of the CDW ground state has remained uncertain because disorder and the presence of superconductivity typically limit the CDW correlation lengths to only a dozen unit cells or less. Here we explore the field-induced 3D CDW correlations in extremely pure detwinned crystals of YBa2Cu3O2 (YBCO) ortho-II and ortho-VIII at magnetic fields in excess of the resistive upper critical field (Hc2) where superconductivity is heavily suppressed. We observe that the 3D CDW is unidirectional and possesses a long in-plane correlation length as well as significant correlations between neighboring CuO2 planes. It is significant that we observe only a single sharply defined transition at a critical field proportional to Hc2, given that the field range used in this investigation overlaps with other high-field experiments including quantum oscillation measurements. The correlation volume is at least two to three orders of magnitude larger than that of the zero-field CDW. This is by far the largest CDW correlation volume observed in any cuprate crystal and so is presumably representative of the high-field ground state of an “ideal” disorder-free cuprate. PMID:27930313

  13. AFM investigations of the morphology features and local mechanical properties of HTS YBCO thin films

    NASA Astrophysics Data System (ADS)

    Soifer, Yakov M.; Verdyan, Armen; Lapsker, Igor; Azoulay, Jacob

    2004-08-01

    In the paper presented here the application of the atomic force microscope (AFM) is considered for evaluation of hardness and Young's modulus of high Tc superconducting YBCO thin films of different thickness (from 0.05 to 1 μm) grown on unbuffered SrTiO 3 (film I) and on sapphire with a buffer layer of CeO 2 (film II). The best film features a transition temperature Tc of 90 K, critical current density Jc ( H=0) of 3 × 10 7 A/cm 2 at 4.2 K and 2 × 10 6 A/cm 2 at 77 K. The relationship between mechanical properties and microstructure of these films was investigated. It was found that all the films comprised well-defined Cu-rich precipitates of different size and with different density on their surface. For both type of films the hardness was measured to be in the range of 12-18 GPa. The Young's modulus of the films was about 180-200 GPa. The nanoindentation and nanoscratching measurements showed that the mechanical strength of the films studied was determined mainly by mechanical failure and surface defects (secondary phases).

  14. Structural ceramics

    NASA Technical Reports Server (NTRS)

    Craig, Douglas F.

    1992-01-01

    This presentation gives a brief history of the field of materials sciences and goes on to expound the advantages of the fastest growing area in that field, namely ceramics. Since ceramics are moving to fill the demand for lighter, stronger, more corrosion resistant materials, advancements will rely more on processing and modeling from the atomic scale up which is made possible by advanced analytical, computer, and processing techniques. All information is presented in viewgraph format.

  15. Relationship between intrinsic surface resistance and critical current density of YBCO thin films with various thickness

    NASA Astrophysics Data System (ADS)

    Nakagawa, K.; Nakayama, S.; Saito, A.; Ono, S.; Kai, H.; Mukaida, M.; Honma, T.; Ohshima, S.

    2010-11-01

    We investigated the relationship between the intrinsic surface resistance (Rsint) and critical current density (Jc) of YBa2Cu3Oy (YBCO) film thinner than the penetration depth (λL). The measured YBCO films were deposited on CeO2-buffered r-cut Al2O3 substrates by the pulsed laser deposition method. The thicknesses of these films were 300, 200, and 100 nm, respectively. The Rsint means the surface resistance of YBCO film removing the loss by the impedance of the substrates. The effective surface resistance (Rseff) including the impedance of the substrate and the Jc of each YBCO film were measured using the dielectric resonator method at 21.8 GHz and the inductive method. We calculated Rsint by using phenomenological expressions and the Rseff value. The Rsint values of each YBCO film were almost the same in the measured temperature region. As a result, we found that Rsint was in inverse proportion to the Jc of YBCO film thinner than λL.

  16. Over-current carrying characteristics of rectangular-shaped YBCO thin films prepared by MOD method

    NASA Astrophysics Data System (ADS)

    Hotta, N.; Yokomizu, Y.; Iioka, D.; Matsumura, T.; Kumagai, T.; Yamasaki, H.; Shibuya, M.; Nitta, T.

    2008-02-01

    A fault current limiter (FCL) may be manufactured at competitive qualities and prices by using rectangular-shaped YBCO films which are prepared by metal-organic deposition (MOD) method, because the MOD method can produce large size elements with a low-cost and non-vacuum technique. Prior to constructing a superconducting FCL (SFCL), AC over-current carrying experiments were conducted for 120 mm long elements where YBCO thin film of about 200 nm in thickness was coated on sapphire substrate with cerium oxide (CeO2) interlayer. In the experiments, only single cycle of the ac damping current of 50 Hz was applied to the pure YBCO element without protective metal coating or parallel resistor and the magnitude of the current was increased step by step until the breakdown phenomena occurred in the element. In each experiment, current waveforms flowing through the YBCO element and voltage waveform across the element were measured to get the voltage-current characteristics. The allowable over-current and generated voltage were successfully estimated for the pure YBCO films. It can be pointed out that the lower n-value trends to bring about the higher allowable over-current and the higher withstand voltage more than tens of volts. The YBCO film having higher n-value is sensitive to the over-current. Thus, some protective methods such as a metal coating should be employed for applying to the fault current limiter.

  17. Structural Ceramics Database

    National Institute of Standards and Technology Data Gateway

    SRD 30 NIST Structural Ceramics Database (Web, free access)   The NIST Structural Ceramics Database (WebSCD) provides evaluated materials property data for a wide range of advanced ceramics known variously as structural ceramics, engineering ceramics, and fine ceramics.

  18. Influence of ceramic thickness and ceramic materials on fracture resistance of posterior partial coverage restorations.

    PubMed

    Bakeman, E M; Rego, N; Chaiyabutr, Y; Kois, J C

    2015-01-01

    This study evaluated the influence of ceramic thickness and ceramic materials on fracture resistance of posterior partial coverage ceramic restorations. Forty extracted molars were allocated into four groups (n=10) to test for two variables: 1) the thickness of ceramic (1 mm or 2 mm) and 2) the ceramic materials (a lithium disilicate glass-ceramic [IPS e.max] or leucite-reinforced glass ceramic [IPS Empress]). All ceramic restorations were luted with resin cement (Variolink II) on the prepared teeth. These luted specimens were loaded to failure in a universal testing machine, in the compression mode, with a crosshead speed of 1.0 mm/min. The data were analyzed using two-way analysis of variance and the Tukey Honestly Significantly Different multiple comparison test (α =0.05). The fracture resistance revealed a significant effect for materials (p<0.001); however, the thickness of ceramic was not significant (p=0.074), and the interaction between the thickness of ceramic and the materials was not significant (p=0.406). Mean (standard deviation) fracture resistance values were as follows: a 2-mm thickness of a lithium disilicate bonded to tooth structure (2505 [401] N) revealed a significantly higher fracture resistance than did a 1-mm thickness of leucite-reinforced (1569 [452] N) and a 2-mm thickness of leucite-reinforced ceramic bonded to tooth structure (1716 [436] N) (p<0.05). There was no significant difference in fracture resistance values between a lithium disilicate ceramic at 1-mm thickness (2105 [567] N) and at 2-mm thickness. Using a lithium disilicate glass ceramic for partial coverage restoration significantly improved fracture resistance compared to using a leucite-reinforced glass ceramic. The thickness of ceramic had no significant effect on fracture resistance when the ceramics were bonded to the underlying tooth structure.

  19. Temperature and Magnetic Field Dependence of Critical Current Density of YBCO with Varying Flux Pinning Additions (POSTPRINT)

    DTIC Science & Technology

    2010-03-01

    coverage corresponding to M phase 1 nm thickness was found to be necessary to increase compared to YBCO . The op- timal layer thickness for each M phase was...kept constant in this experiment: , Y211 0.8 nm , and [17]. Using the optimal M phase thickness, the YBCO layer was also systematically varied for...AFRL-RZ-WP-TP-2010-2083 TEMPERATURE AND MAGNETIC FIELD DEPENDENCE OF CRITICAL CURRENT DENSITY OF YBCO WITH VARYING FLUX PINNING ADDITIONS

  20. Effects of deposition rate and thickness on the properties of YBCO films deposited by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Shi, D. Q.; Ko, R. K.; Song, K. J.; Chung, J. K.; Choi, S. J.; Park, Y. M.; Shin, K. C.; Yoo, S. I.; Park, C.

    2004-02-01

    YBCO films with various thicknesses from 100 nm to 1.6 µm were deposited on single crystal SrTiO3 substrates by pulsed laser deposition (PLD). The effects of thickness and deposition rate—by means of controlling the pulsed laser frequency—on the critical current density (Jc) were studied. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to examine the orientation, crystallization and surface quality. The amount of a-axis YBCO component evaluated from the ratio of XRD chi-scan intensities of the a-axis and c-axis for the YBCO (102) plane increased as the YBCO film became thicker. SEM was used to analyse the surface of YBCO film, and it was shown that the surface of YBCO film became rougher with increasing thickness. There were many large singular outgrowths and networks of outgrowths on the surface of the YBCO films with thickness greater than 0.4 µm. The increased amount of a-axis YBCO component and the coarse microstructure of the thick YBCO film caused degradation of Jc with increasing thickness.

  1. Fiber optic quench detection via optimized Rayleigh Scattering in high-field YBCO accelerator magnets

    SciTech Connect

    Flanagan, Gene

    2016-02-17

    Yttrium barium copper oxide (YBCO) coated conductors are known for their ability to operate in the superconducting state at relatively high temperatures, even above the boiling point of liquid nitrogen (77 K). When these same conductors are operated at lower temperatures, they are able to operate in much higher magnetic fields than traditional superconductors like NiTi or Nb3Sn. Thus, YBCO superconducting magnets are one of the primary options for generating the high magnetic fields needed for future high energy physics devices. Due to slow quench propagation, quench detection remains one of the primary limitations to YBCO magnets. Fiber optic sensing, based upon Rayleigh scattering, has the potential for spatial resolution approaching the wavelength of light, or very fast temporal resolution at low spatial resolution, and a continuum of combinations in between. This project has studied, theoretically and experimentally, YBCO magnets and Rayleigh scattering quench detection systems to demonstrate feasibility of the systems for YBCO quench protection systems. Under this grant an experimentally validated 3D quench propagation model was used to accurately define the acceptable range of spatial and temporal resolutions for effective quench detection in YBCO magnets and to evaluate present-day and potentially improved YBCO conductors. The data volume and speed requirements for quench detection via Rayleigh scattering required the development of a high performance fiber optic based quench detection/data acquisition system and its integration with an existing voltage tap/thermo-couple based system. In this project, optical fibers are tightly co-wound into YBCO magnet coils, with the fiber on top of the conductor as turn-to-turn insulation. Local changes in the temperature or strain of the conductor are sensed by the optical fiber, which is in close thermal and mechanical contact with the conductor. Intrinsic imperfections in the fiber reflect Rayleigh

  2. Superconductor-Mediated Modification of Gravity? AC Motor Experiments with Bulk YBCO Disks in Rotating Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Noever, David A.; Koczor, Ronald J.; Roberson, Rick

    1998-01-01

    We have previously reported results using a high precision gravimeter to probe local gravity changes in the neighborhood of large bulk-processed high-temperature superconductors. Podkietnov, et al (Podkietnov, E. and Nieminen, R. (1992) A Possibility of Gravitational Force Shielding by Bulk YBa2 Cu3 O7-x Superconductor, Physica C, C203:441-444.) have indicated that rotating AC fields play an essential role in their observed distortion of combined gravity and barometric pressure readings. We report experiments on large (15 cm diameter) bulk YBCO ceramic superconductors placed in the core of a three-phase, AC motor stator. The applied rotating field produces up to a 12,000 revolutions per minute magnetic field. The field intensity decays rapidly from the maximum at the outer diameter of the superconducting disk (less than 60 Gauss) to the center (less than 10 Gauss). This configuration was applied with and without a permanent DC magnetic field levitating the superconducting disk, with corresponding gravity readings indicating an apparent increase in observed gravity of less than 1 x 10(exp -6)/sq cm, measured above the superconductor. No effect of the rotating magnetic field or thermal environment on the gravimeter readings or on rotating the superconducting disk was noted within the high precision of the observation. Implications for propulsion initiatives and power storage flywheel technologies for high temperature superconductors will be discussed for various spacecraft and satellite applications.

  3. Elastic Domain Wall Waves in Ferroelectric Ceramics and Single Crystals

    DTIC Science & Technology

    1988-07-01

    and identify by block number) " This report reviews research on acoustic guided waves along poling transitions in counter- poled ferroelectric ceramics...INTRODUCTION........................................ 1 II. GENERAL REVIEW . .. .......... ........... ... 2 (a) COUNTERPOLED CERAMICS...and better understanding of new ferroelectric materials. II. GENERAL REVIEW The initial phase of this project was an in-depth study of elastic wave

  4. Passivation of Flexible YBCO Superconducting Current Lead With Amorphous SiO2 Layer

    NASA Technical Reports Server (NTRS)

    Johannes, Daniel; Webber, Robert

    2013-01-01

    Adiabatic demagnetization refrigerators (ADR) are operated in space to cool detectors of cosmic radiation to a few 10s of mK. A key element of the ADR is a superconducting magnet operating at about 0.3 K that is continually energized and de-energized in synchronism with a thermal switch, such that a piece of paramagnetic salt is alternately warm in a high magnetic field and cold in zero magnetic field. This causes the salt pill or refrigerant to cool, and it is able to suck heat from an object, e.g., the sensor, to be cooled. Current has to be fed into and out of the magnets from a dissipative power supply at the ambient temperature of the spacecraft. The current leads that link the magnets to the power supply inevitably conduct a significant amount of heat into the colder regions of the supporting cryostat, resulting in the need for larger, heavier, and more powerful supporting refrigerators. The aim of this project was to design and construct high-temperature superconductor (HTS) leads from YBCO (yttrium barium copper oxide) composite conductors to reduce the heat load significantly in the temperature regime below the critical temperature of YBCO. The magnet lead does not have to support current in the event that the YBCO ceases to be superconducting. Cus - tomarily, a normal metal conductor in parallel with the YBCO is a necessary part of the lead structure to allow for this upset condition; however, for this application, the normal metal can be dispensed with. Amorphous silicon dioxide is deposited directly onto the surface of YBCO, which resides on a flexible substrate. The silicon dioxide protects the YBCO from chemically reacting with atmospheric water and carbon dioxide, thus preserving the superconducting properties of the YBCO. The customary protective coating for flexible YBCO conductors is silver or a silver/gold alloy, which conducts heat many orders of magnitude better than SiO2 and so limits the use of such a composite conductor for passing current

  5. Ceramic Seal.

    SciTech Connect

    Smartt, Heidi A.; Romero, Juan A.; Custer, Joyce Olsen; Hymel, Ross W.; Krementz, Dan; Gobin, Derek; Harpring, Larry; Martinez-Rodriguez, Michael; Varble, Don; DiMaio, Jeff; Hudson, Stephen

    2016-11-01

    Containment/Surveillance (C/S) measures are critical to any verification regime in order to maintain Continuity of Knowledge (CoK). The Ceramic Seal project is research into the next generation technologies to advance C/S, in particular improving security and efficiency. The Ceramic Seal is a small form factor loop seal with improved tamper-indication including a frangible seal body, tamper planes, external coatings, and electronic monitoring of the seal body integrity. It improves efficiency through a self-securing wire and in-situ verification with a handheld reader. Sandia National Laboratories (SNL) and Savannah River National Laboratory (SRNL), under sponsorship from the U.S. National Nuclear Security Administration (NNSA) Office of Defense Nuclear Nonproliferation Research and Development (DNN R&D), have previously designed and have now fabricated and tested Ceramic Seals. Tests have occurred at both SNL and SRNL, with different types of tests occurring at each facility. This interim report will describe the Ceramic Seal prototype, the design and development of a handheld standalone reader and an interface to a data acquisition system, fabrication of the seals, and results of initial testing.

  6. Inverse polarity of the resistive switching effect and strong inhomogeneity in nanoscale YBCO-metal contacts

    NASA Astrophysics Data System (ADS)

    Truchly, M.; Plecenik, T.; Zhitlukhina, E.; Belogolovskii, M.; Dvoranova, M.; Kus, P.; Plecenik, A.

    2016-11-01

    We have studied a bipolar resistive switching phenomenon in c-axis oriented normal-state YBa2Cu3O7-c (YBCO) thin films at room temperature by scanning spreading resistance microscopy (SSRM) and scanning tunneling microscopy (STM) techniques. The most striking experimental finding has been the opposite (in contrast to the previous room and low-temperature data for planar metal counter-electrode-YBCO bilayers) voltage-bias polarity of the switching effect in all SSRM and a number of STM measurements. We have assumed that the hysteretic phenomena in current-voltage characteristics of YBCO-based contacts can be explained by migration of oxygen-vacancy defects and, as a result, by the formation or dissolution of more or less conductive regions near the metal-YBCO interface. To support our interpretation of the macroscopic resistive switching phenomenon, a minimalist model that describes radical modifications of the oxygen-vacancy effective charge in terms of a charge-wind effect was proposed. It was shown theoretically that due to the momentum exchange between current carriers (holes in the YBCO compound) and activated oxygen ions, the direction in which oxygen vacancies are moving is defined by the balance between the direct electrostatic force on them and that caused by the current-carrier flow.

  7. Effects of deposition conditions on the phase formation of YBCO films prepared by spray pyrolysis method

    NASA Astrophysics Data System (ADS)

    Kim, Ho-Jin; Joo, Jinho; Park, Shin-Geun; Hong, Suck-Kwan; Lee, Sun-Wang; Lim, Sun-Weon; Hong, Gye-Won; Lee, Hee-Gyoun

    2006-10-01

    YBa2Cu3Oy superconducting films were deposited on LaAlO3(1 0 0) single crystal substrates by spray pyrolysis method. Two types of ultrasonic and concentric nebulizer were used in order to generate fine droplets of metal-inorganic precursor solution. c-Axis oriented films were obtained at deposition temperature of 750-850 °C and at working pressures of 100 Torr and 500 Torr. In case of ultrasonic nebulizer, the films showed rough surface morphology due to the presence of enormous droplets, whereas smooth and dense films were obtained for concentric nebulizer. The good c-axis oriented YBCO films were formed at the wide range of the oxygen partial pressure. Oxygen which is generated via the decomposition of nitrate precursors is considered to participate in the formation reaction of YBCO film. Microstructures of YBCO films varied depending on oxygen partial pressure and rod-like grains were appeared when the oxygen partial pressure was lower than 30 Torr. YBCO films were deposited epitaxially on LAO(1 0 0) substrate. Δϕ of in-plane and Δω of out-of-plane texture were measured as 3.3° and 1.0°, respectively. A transport Jc value of 0.50 MA/cm2 at 77 K and self-field was achieved for the YBCO film deposited on LaAlO3(1 0 0) single crystal substrate.

  8. Unique nanostructural features in Fe, Mn-doped YBCO thin films

    NASA Astrophysics Data System (ADS)

    Meledin, A.; Turner, S.; Cayado, P.; Mundet, B.; Solano, E.; Ricart, S.; Ros, J.; Puig, T.; Obradors, X.; Van Tendeloo, G.

    2016-12-01

    An attempt to grow a thin epitaxial composite film of YBa2Cu3O7-δ (YBCO) with spinel MnFe2O4 (MFO) nanoparticles on a LAO substrate using the CSD approach resulted in a decomposition of the spinel and various doping modes of YBCO with the Fe and Mn cations. These nanostructural effects lead to a lowering of T c and a slight J c increase in field. Using a combination of advanced transmission electron microscopy (TEM) techniques such as atomic resolution high-angle annular dark field scanning TEM, energy dispersive x-ray spectroscopy and electron energy-loss spectroscopy we have been able to decipher and characterize the effects of the Fe and Mn doping on the film architecture. The YBaCuFeO5 anion-deficient double perovskite phase was detected in the form of 3D inclusions as well as epitaxially grown lamellas within the YBCO matrix. These nano-inclusions play a positive role as pinning centers responsible for the J c/J sf (H) dependency smoothening at high magnetic fields in the YBCO-MFO films with respect to the pristine YBCO films.

  9. Critical Exponents of the Superconducting Transition in Polycrystalline YBCO.

    NASA Astrophysics Data System (ADS)

    Joshi, R. J.; Hallock, R. B.; Taylor, J. A.

    1996-03-01

    We present results of measurements designed to study superconducting I-V scaling in samples of bulk YBCO with varying morphologies and at selected magnetic fields 0.5<= H<= 10 T. I-V isotherm measurements performed near the superconducting transition on the samples are consistent with recent predictions of I-V scaling, with critical exponents ν≈ 1.2-1.5 and z≈ 2.6-4. The values for ν are comparable to those previously(T.K. Worthington, E. Olsson, C.S. Nichols, T.M. Shaw and D.R. Clarke, Phys. Rev. B 43), 10538 (1991) . reported(R.H. Koch, V. Foglietti, W.J. Gallagher,G. Koren, A. Gupta and M.P.A. Fisher, Phys. Rev. Lett. 63), 1511 (1989).. The values for z are consistent with those reported by Tiernan and Hallock(W.M. Tiernan, R. Joshi and R.B. Hallock, Phys. Rev. B. 48), 3423 (1993). but are somewhat lower than what is predicted by the glassy models. The morpholoogy and magnetic field dependence of z will be described.

  10. Far-infrared Hall Effect in YBCO films

    NASA Astrophysics Data System (ADS)

    Grayson, M.; Rigal, L.; Cerne, J.; Schmadel, D. C.; Drew, H. D.; Kung, P.-J.

    2001-03-01

    In order to gain insight into the so-called "anomalous Hall effect" in Hi Tc superconductors(T.R. Chien, D.A. Brawner, Z.Z. Wang, and N.P. Ong, PRB 43, 6242(1991).) we explore Hall measurements at far-infrared (FIR) frequencies and study the temperature dependence. We separately measure the real and imaginary parts of the magneto-optical response of YBCO thin films to polarized FIR light (15-250 cm-1). The induced rotation of linearly polarized light tells us the real part of the Faraday angle, Re[θ_F(ω)], and the induced dichroism of circularly polarized light tells us Im[θ_F(ω)]. We can then deduce the complex Hall angle without resorting to Kramers-Kronig (K-K) analysis. Since both the Hall angle and the Faraday angle obey sum rules, we can compare to higher frequencies(Cerne, et al., invited talk) and determine additional information about the spectral response at intermediate frequencies. The consistency of these results is verified with K-K analysis.

  11. Phase dynamics of low critical current density YBCO Josephson junctions

    NASA Astrophysics Data System (ADS)

    Massarotti, D.; Stornaiuolo, D.; Rotoli, G.; Carillo, F.; Galletti, L.; Longobardi, L.; Beltram, F.; Tafuri, F.

    2014-08-01

    High critical temperature superconductors (HTS) based devices can have impact in the study of the phase dynamics of Josephson junctions (JJs) thanks to the wide range of junction parameters they offer and to their unconventional properties. Measurements of current-voltage characteristics and of switching current distributions constitute a direct way to classify different regimes of the phase dynamics and of the transport, also in nontrivial case of the moderately damped regime (MDR). MDR is going to be more and more common in JJs with advances in nanopatterning superconductors and synthesizing novel hybrid systems. Distinctive signatures of macroscopic quantum tunneling and of thermal activation in presence of different tunable levels of dissipation have been detected in YBCO grain boundary JJs. Experimental data are supported by Monte Carlo simulations of the phase dynamics, in a wide range of temperatures and dissipation levels. This allows us to quantify dissipation in the MDR and partially reconstruct a phase diagram as guideline for a wide range of moderately damped systems.

  12. Sputter Synthesis of c-axis YBCO Films with Excellent Surface Smoothness and Fabrication of Sandwich type Junctions with Interface Engineered Barrier

    NASA Astrophysics Data System (ADS)

    Ohk, K.; Iwashita, N.; Kikunaga, K.; Okuda, T.; Obara, K.; Terada, N.

    2006-06-01

    Flat surface is essential to base electrodes of sandwich type Josephson junctions. In the present study, c-axis YBa2Cu3O7 (c-YBCO) films with excellent surface smoothness were fabricated by off-axis sputtering. For the flat surfaces, key parameters in the sputtering process were growth temperature, atmosphere conditions and surface nature of substrates. The correlation between the sputtering conditions and the characteristic of the c-YBCO films reveal the following phenomena; i) The films deposited at low temperature of 660 °C showed a low zero-resistance temperature because of a poor connection between the c-axis crystallites. Surfaces of these low temperature grown films involve large and rectangular shaped a-axis grains, thereby the peak-to-valley (PV) amplitude of the surface was beyond 80 nm. The experiments indicate that the growth of the grains should be caused by low surface diffusion of adatoms at the low growth temperature. ii) Contrarily, at high Ts above 770 °C, a serious deviation of film composition from the stoichiometry took places, which also promoted an outgrowth of a-axis grains. Consequently, the high temperature grown films had seriously rough surfaces (PV amplitude > 25 nm). iii) The growth at the optimised Ts of 765 °C led a remarkable reduction of surface roughness (root-mean-square (RMS) of the roughness < 1.8 nm) without any degradation of superconducting properties. The achieved surface morphology is classified as one of the smoothest surfaces of the YBCO film grow by sputtering. iv) A density of the a-axis outgrowth was related to the surface defects of the substrate. The usage of SrTiO3 (100) plane consists of atomically flat and wide terraces and unit-cell high steps resulted in almost outgrowth-face surface with an excellent smoothness (PV amplitude < 10 nm, RMS of the roughness < 1.0 nm).

  13. Degradation of the performance of a YBCO-coated conductor double pancake coil due to epoxy impregnation

    NASA Astrophysics Data System (ADS)

    Takematsu, T.; Hu, R.; Takao, T.; Yanagisawa, Y.; Nakagome, H.; Uglietti, D.; Kiyoshi, T.; Takahashi, M.; Maeda, H.

    2010-09-01

    Now that YBCO-coated conductors have been commercialized, a number of YBCO coils have been developed. However, their basic performances have not been systematically investigated so far. Here, we demonstrate that of a YBCO double pancake coil. The critical current of an epoxy impregnated YBCO double pancake coil was substantially degraded, i.e. the normal voltage appears above 8 A, only 18% of that for the dry coil. It was inferred that degradation occurs if the cumulative radial stress developed during cool down exceeds the critical transverse stress for the YBCO-coated conductor (typically 10 MPa). Under these conditions, the conductor was debonded at the interface between the buffer layer and YBCO layers, or fractured in the YBCO layer itself, causing cracks on the YBCO layer, resulting in a significant decline of the critical current. These negative effects are suppressed if the coils are dry wound or impregnated with paraffin, as the bonding strengths between turns are negligible and therefore turns are separated if the cumulative radial stress tends to be tensile. For non-circular coils in which epoxy impregnation is inevitable, degradation due to cumulative tensile transverse stress is still the major problem.

  14. Superconductivity, structure visualization, mechanical strength promotion and Raman spectra of hafnium-doped-123-YBCO synthesized via urea precursor route

    NASA Astrophysics Data System (ADS)

    Elsabawy, Khaled M.

    2011-08-01

    The pure YBCO (YBa2Cu3O7) and its variant hafnium containing superconductors with general formula: Y1-xHfxBa2Cu3Oz, where x = 0.1, 0.2, and 0.4 mole, respectively, were synthesized by solution route using urea as precursor forming agent. X-ray measurements indicated that Hf4+ ions have a negligible effect on the main crystalline structure and substitute Y-sites successfully in lattice structure of 123-YBCO at low levels of hafnium doping (x = 0.1 → 0.2 mole). From SE-microscopy mapping and EDX elemental analysis Hf4+ was detected qualitatively with good approximation to the actual molar ratio but not observed at 123-YBCO grain boundaries which confirm that hafnium (IV) has diffused regularly into material bulk of superconducting 123-YBCO-phase at low levels of concentrations. Structure visualization of Hf-doped-123-YBCO was made to confirm success of hafnium substitutions inside crystal lattice on Y-sites of 123-YBCO superconductors. Hafnium dopings affected sharply on the main vibrating modes of YBCO regime particularly on the apical oxygen (O4) vibrational mode A1g. Magnetic susceptibility measurements proved that hafnium dopings have strong effect on the transport properties of YBCO-composites regime. Hafnium promotes mechanical tensile coefficient recording maxima 35.7 MPa for x = 0.4 mole.

  15. Remanent magnetization of ceramic and single-crystal high-Tc superconductors in tilted magnetic fields

    NASA Astrophysics Data System (ADS)

    Bugoslavsky, Yu. V.; Minakov, A. A.; Vasyurin, S. I.

    1996-02-01

    Dependence of the remanent magnetization (Mr) anisotropy on the structure and shape of the superconductor and on the magnetizing procedure was studied for a number of high-Tc superconductor ceramics and single crystals. The experiments were done by means of a vibrating-sample magnetometer with a rotatable sample holder. It was found that the main contribution to the anisotropic behavior of Mr is due to the surface screening currents, and therefore the anisotropy is subject to variation when sample shape is changed. The question is resolved, why the effective demagnetization factors for decoupled ceramic samples are different from those calculated in the inscribed-ellipsoid approximation. Influence of inhomogeneous grain magnetization and global bulk currents on the angular dependencies of Mr in ceramic samples is investigated. The evolution of remanence in YBCO single crystals with an increase of the magnetizing field is described within an extended Bean model.

  16. YBCO and LSMO nano-films and sandwiches prepared by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Nurgaliev, T.; Mateev, E.; Blagoev, B.; Miteva, S.; Neshkov, L.; Strbik, V.; Uspenskaya, L. S.; Benacka, S.; Chromik, S.; Nedkov, I.

    2010-06-01

    DC and RF magnetron sputtering techniques were used for growing nano-films (t<100 nm) of high temperature superconducting (HTS) YBa2Cu3O7 (YBCO) and ferromagnetic (FM) manganite La0.7Sr0.3Mn03 (LSMO) materials on LaAlO3 (LAO) and Al2O3 (ALO) substrates as well as for preparing of single-, double- and three-layer structures in different areas of the same substrates. The procedure allowed growing of structures on LAO substrates where the critical temperature of YBCO thin film components was more than 84 K. The LSMO films grown ALO substrates were ferromagnetic while the YBCO films grown on LSMO/ALO did not demonstrate superconductivity.

  17. Role of twin boundaries on vortex pinning of CSD YBCO nanocomposites

    NASA Astrophysics Data System (ADS)

    Rouco, V.; Palau, A.; Guzman, R.; Gazquez, J.; Coll, M.; Obradors, X.; Puig, T.

    2014-12-01

    We study the effect of twin boundaries (TBs) on the critical current density of YBa2Cu3O7-x (YBCO) films and nanocomposites grown on different substrates. Varying both the direction of the current and magnetic field, we show that the TB orientation is a crucial parameter to consider in the optimization of Jc for particular applications. A quantitative and detailed analysis of the role of TBs on vortex dynamics has allowed us to infer that extended TB planes in pristine YBCO films can reduce Jc by 60% at low temperatures due to vortex channeling effects or increase it by a 98% at high temperatures due to directional vortex pinning. Moreover, we demonstrate that TB length and distribution can be strongly modified in YBCO nanocomposites. We observe that TB planes with no vertical coherence are still effective for vortex pinning while are not to create channels for easy vortex flow.

  18. Ideal charge-density-wave order in the high-field state of superconducting YBCO

    NASA Astrophysics Data System (ADS)

    Jang, H.; Lee, W.-S.; Nojiri, H.; Matsuzawa, S.; Yasumura, H.; Nie, L.; Maharaj, A. V.; Gerber, S.; Liu, Y.-J.; Mehta, A.; Bonn, D. A.; Liang, R.; Hardy, W. N.; Burns, C. A.; Islam, Z.; Song, S.; Hastings, J.; Devereaux, T. P.; Shen, Z.-X.; Kivelson, S. A.; Kao, C.-C.; Zhu, D.; Lee, J.-S.

    2016-12-01

    The existence of charge-density-wave (CDW) correlations in cuprate superconductors has now been established. However, the nature of the CDW ground state has remained uncertain because disorder and the presence of superconductivity typically limit the CDW correlation lengths to only a dozen unit cells or less. Here we explore the field-induced 3D CDW correlations in extremely pure detwinned crystals of YBa2Cu3O2 (YBCO) ortho-II and ortho-VIII at magnetic fields in excess of the resistive upper critical field (Hc2Hc2) where superconductivity is heavily suppressed. We observe that the 3D CDW is unidirectional and possesses a long in-plane correlation length as well as significant correlations between neighboring CuO2 planes. It is significant that we observe only a single sharply defined transition at a critical field proportional to Hc2Hc2, given that the field range used in this investigation overlaps with other high-field experiments including quantum oscillation measurements. The correlation volume is at least two to three orders of magnitude larger than that of the zero-field CDW. This is by far the largest CDW correlation volume observed in any cuprate crystal and so is presumably representative of the high-field ground state of an “ideal” disorder-free cuprate.

  19. Microwave processing of ceramics

    SciTech Connect

    Katz, J.D.

    1989-01-01

    This paper discusses the following topics on microwave processing of ceramics: Microwave-material interactions; anticipated advantage of microwave sintering; ceramic sintering; and ceramic joining. 24 refs., 4 figs. (LSP)

  20. Detectors of Infrared Radiation Based on High T(c) Superconducting YBCO Films

    DTIC Science & Technology

    1988-02-23

    of the YBCO films. Second, the best (epitaxial) super- conducting YBCO films are grown on the SrTiO3 substrates, which may be disadvantageous for...sintered pellets, thin films, single crystals and fibers. We have grown thin BCSCO films on SrTiO3 substrates( 3 ); they showed zero resistance at Tc...is a "line" .., compound - i.e. it forms at nearly exact stoichiometry composition. As it grows epitaxially on the (001) face of SrTiO3 substrate, it

  1. Morphology and etching studies on YBCO and CuO single crystals

    NASA Astrophysics Data System (ADS)

    Prabhakaran, D.; Subramanian, C.; Balakumar, S.; Ramasamy, P.

    1999-06-01

    Single crystals of YBCO (Y123) and CuO have been grown from a BaO-CuO (28:72) flux using a low axial gradient furnace (∼1°C/cm). Growth morphology of the grown crystals was studied using an optical microscope, scanning electron microscopy and atomic force microscopy. Cell parameter values and chemical composition of the grown crystals were determined from the X-ray diffraction data and inductively coupled plasma analysis, respectively. Etching studies were done for both the crystals using different etchants. Oxygen stoichiometry of the YBCO crystal was determined by iodometry titration analysis.

  2. YBCO thin film evaporation on as-deposited silver film on MgO

    NASA Astrophysics Data System (ADS)

    Azoulay, J.

    1999-11-01

    YBa 2Cu 3O 7- δ (YBCO) thin film was evaporated on as-deposited Ag buffer layer on MgO substrate. A simple, inexpensive vacuum system equipped with one resistively heated source was used. The subsequent heat treatment was carried out under low oxygen partial pressure at a relatively low temperature and short dwelling time. The films thus obtained were characterized for electrical properties using DC four-probe electrical measurements and inspected for structural properties and chemical composition by scanning electron microscopy (SEM). It is shown that YBCO thin film can grow on as-deposited thin silver layer on MgO substrate.

  3. Process for making ceramic insulation

    DOEpatents

    Akash, Akash; Balakrishnan, G. Nair

    2009-12-08

    A method is provided for producing insulation materials and insulation for high temperature applications using novel castable and powder-based ceramics. The ceramic components produced using the proposed process offers (i) a fine porosity (from nano-to micro scale); (ii) a superior strength-to-weight ratio; and (iii) flexibility in designing multilayered features offering multifunctionality which will increase the service lifetime of insulation and refractory components used in the solid oxide fuel cell, direct carbon fuel cell, furnace, metal melting, glass, chemical, paper/pulp, automobile, industrial heating, coal, and power generation industries. Further, the ceramic components made using this method may have net-shape and/or net-size advantages with minimum post machining requirements.

  4. Gamma radiation effects on some properties of YBCO

    NASA Astrophysics Data System (ADS)

    Luo, L.; Zhang, Y. H.; Hu, S. H.; Liu, W. H.; Zhang, G. L.; Hu, W. X.

    1991-07-01

    Radiation effects of polycrystalline YBCO bulk sample irradiated by 60Co γ-rays, dose of 1×10 6 up to 7.5×10 8 rad, at room temperature on critical temperature and critical current were investigated. IR spectrum was also used to study the mechanism of the irradiation. A considerably strong dependence of these parameters upon the irradiation dose was observed. No significant effects on the critical temperature were found, but the critical current in zero magnetic field changed greatly. It shows a tendency to decrease with the increase of the irradiation dose except for a slight increase with the dose less than about 2×10 7 rad and no simple relations between critical currents and irradiation doses was found. A typical case is that the critical current is reduced to about 60% when the dose reaches 5×10 9 rad, but the dependence of critical currents on the magnetic field shows that the critical currents are higher than those of the unirradiated one in the range of magnetic field higher than 100 G and decrease more slowly in a magnetic field compared with the unirradiated one. The results indicate that the defects produced by γ-ray irradiation are beneficial to flux pinning in higher fields. IR spectra analysis reveals that the intensity of the peak responsible for the Cu(1)- O(1) chain vibration is decreased, indicating that the bond of the Cu(1)-O(1) may be partly broken through collision process of the Compton electron produced by the γ-ray. This effect probably gives rise to a decrease of the critical currents.

  5. Mixed-mode fracture of ceramics

    SciTech Connect

    Petrovic, J.J.

    1985-01-01

    The mixed-mode fracture behavior of ceramic materials is of importance for monolithic ceramics in order to predict the onset of fracture under generalized loading conditions and for ceramic composites to describe crack deflection toughening mechanisms. Experimental data on surface flaw mixed-mode fracture in various ceramics indicate that the flaw-plane normal stress at fracture decreases with increasing in-flaw-plane shear stress, although present data exhibit a fairly wide range in details of this sigma - tau relationship. Fracture from large cracks suggests that Mode II has a greater effect on Mode I fracture than Mode III. A comparison of surface flaw and large crack mixed-mode I-II fracture responses indicated that surface flaw behavior is influenced by shear resistance effects.

  6. Dynamical effects of an unconventional current-phase relation in YBCO dc SQUIDs.

    PubMed

    Lindström, T; Charlebois, S A; Tzalenchuk, A Ya; Ivanov, Z; Amin, M H S; Zagoskin, A M

    2003-03-21

    The predominant d-wave pairing symmetry in high-temperature superconductors allows for a variety of current-phase relations in Josephson junctions, which is to a certain degree fabrication controlled. In this Letter, we report on direct experimental observations of the effects of a nonsinusoidal current-phase dependence in YBCO dc SQUIDs, which agree with the theoretical description of the system.

  7. Experimental studies of helical solenoid model based on YBCO tape-bridge joints

    SciTech Connect

    Yu, M.; Lombardo, V.; Turrioni, D.; Zlobin, A.V.; Flangan, G.; Lopes, M.L.; Johnson, R.P.; /Fermilab

    2011-06-01

    Helical solenoids that provide solenoid, helical dipole and helical gradient field components are designed for a helical cooling channel (HCC) proposed for cooling of muon beams in a muon collider. The high temperature superconductor (HTS), 12 mm wide and 0.1 mm thick YBCO tape, is used as the conductor for the highest-field section of HCC due to certain advantages, such as its electrical and mechanical properties. To study and address the design, and technological and performance issues related to magnets based on YBCO tapes, a short helical solenoid model based on double-pancake coils was designed, fabricated and tested at Fermilab. Splicing joints were made with Sn-Pb solder as the power leads and the connection between coils, which is the most critical element in the magnet that can limit the performance significantly. This paper summarizes the test results of YBCO tape and double-pancake coils in liquid nitrogen and liquid helium, and then focuses on the study of YBCO splices, including the soldering temperatures and pressures, and splice bending test.

  8. R.F. Sputtering Deposition of Buffer Layers for Si/YBCO Integrated Microelectronics

    NASA Astrophysics Data System (ADS)

    Rombolà, G.; Ballarini, V.; Chiodoni, A.; Gozzelino, L.; Mezzetti, E.; Minetti, B.; Pirri, C. F.; Tresso, E.; Camerlingo, C.

    The aim of the present work is the optimization of the Si/buffer-layer/YBCO multilayer deposition process so as to grow superconducting films of quality suitable for device applications. The structural properties of the Si/CeO2 system, obtained by RF magnetron sputtering of CeO2 targets in Ar atmosphere, have been studied. More than 50 films have been deposited and some of them submitted to post-deposition annealing treatments both in N2 and O2 atmospheres. The presence of an unwanted amorphous SiO2 layer at the Si/CeO2 interface compromises the YBCO c-axis orientation, and therefore the sharpness of the R versus T transition. A newly designed deposition system has been realized: it has been specially conceived for obtaining bi- and tri-layers, adopting two targets in YSZ and CeO2, respectively. Results on YSZ/Si and CeO2/YSZ/Si systems obtained with the new machine are presented and discussed: (100) oriented YSZ films with nominal thickness of 40 nm have been obtained. The CeO2 film subsequently deposited has the desired (100) orientation. The YBCO film, in the final YBCO/YSZ/CeO2/Si configuration, is c-axis oriented.

  9. New method for introducing nanometer flux pinning centers into single domain YBCO bulk superconductors

    NASA Astrophysics Data System (ADS)

    Yang, W. M.; Wang, Miao

    2013-10-01

    Single domain YBCO superconductors with different additions of Bi2O3 have been fabricated by top seeded infiltration and growth process (TSIG). The effect of Bi2O3 additions on the growth morphology, microstructure and levitation force of the YBCO bulk superconductor has been investigated. The results indicate that single domain YBCO superconductors can be fabricated with the additions of Bi2O3 less than 2 wt%; Bi2O3 can be reacted with Y2BaCuO5 and liquid phase and finally form Y2Ba4CuBiOx(YBi2411) nanoscale particles; the size of the YBi2411 particles is about 100 nm, which can act as effective flux pinning centers. It is also found that the levitation force of single domain YBCO bulks is increasing from 13 N to 34 N and decreasing to 11 N with the increasing of Bi2O3 addition from 0.1 wt% to 0.7 wt% and 2 wt%. This result is helpful for us to improve the physical properties of REBCO bulk superconductors.

  10. Ordered YBCO sub-micron array structures induced by pulsed femtosecond laser irradiation.

    PubMed

    Luo, C W; Lee, C C; Li, C H; Shih, H C; Chen, Y-J; Hsieh, C C; Su, C H; Tzeng, W Y; Wu, K H; Juang, J Y; Uen, T M; Chen, S P; Lin, J-Y; Kobayashi, T

    2008-12-08

    We report on the formation of organized sub-micron YBa(2)Cu(3)O(7) (YBCO) dots induced by irradiating femtosecond laser pulses on YBCO films prepared by pulse laser deposition with fluence in the range of 0.21 approximately 0.53 J/cm(2). The morphology of the YBCO film surface depends strongly on the laser fluences irradiated. At lower laser fluence (approximately 0.21 J/cm(2)) the morphology was pattern of periodic ripples with sub-micrometer spacing. Slightly increasing the laser fluence to 0.26 J/cm(2) changes the pattern into organized sub-micron dots with diameters ranging from 100 nm to 800 nm and height of 150 nm. Further increase of the laser fluence to over 0.32 J/cm(2), however, appeared to result in massive melting and led to irregular morphology. The mechanism and the implications of the current findings will be discussed. Arrays of YBCO sub-micron dots with T(c) = 89.7 K were obtained.

  11. Enhanced pinning in YBCO films with BaZrO.sub.3 nanoparticles

    DOEpatents

    Driscoll, Judith L.; Foltyn, Stephen R.

    2010-06-15

    A process and composition of matter are provided and involve flux pinning in thin films of high temperature superconductive oxides such as YBCO by inclusion of particles including barium and a group 4 or group 5 metal, such as zirconium, in the thin film.

  12. Continued improvment of large area, in situ sputter deposition of superconducting YBCO thin films

    NASA Technical Reports Server (NTRS)

    Truman, J. K.; White, W. R.; Ballentine, P. H.; Mallory, D. S.; Kadin, A. M.

    1993-01-01

    The deposition of thin films of superconducting YBa2Cu3O7-x onto substrates of up to 3-in diameter by an integrated off-axis sputtering is reported. The substrate is located above the center of an 8-in-diameter YBCO planar target, and, in conjunction with a negative ion shield, negative ion effects are avoided. A large radiant heater provides backside, noncontact heating of the bare substrates. YBCO films have been grown on polished 1-cm2 MgO and LaAlO3 substrates with Tc = 90 K or greater, Jc = 2.5 x 10 exp 6 A/sq cm or greater at 77 K, and microwave surface resistance Rs less than 0.4 micro-ohm at 77 K and 10 GHz. The films have a very smooth surface morphology. Uniformity data for LaAlO3 substrates are less than +/-5 percent in Rs. Thickness uniformity results for 3-in substrates indicate less than 10 percent variation. The growth of epitaxial insulating films for use with YBCO films and application of the YBCO films in microwave devices are briefly discussed.

  13. A newly designed ultrasonic spray pyrolysis device to fabricate YBCO tapes

    NASA Astrophysics Data System (ADS)

    Liu, M.; Zhou, M. L.; Zhai, L. H.; Liu, D. M.; Gao, X.; Liu, W.

    2003-04-01

    A newly designed ultrasonic spray pyrolysis device has been manufactured to fabricate YBCO tapes. The apparatus is primarily composed of four zones: the ultrasonic generator, the atomization chamber, the pyrolysis chamber and the rotating equipment. Every part of them is designed and fabricated by us. The whole system costs far less than the ready-made equipment facility in which there is always a vacuum apparatus. This apparatus with processing parameters accurately controlled can fabricate short and long YBCO tapes. In this paper, we mainly focused on how to design and manufacture four parts of the ultrasonic spray pyrolysis. We have deposited c-axis aligned short YBCO tapes on biaxially textured Ag {1 1 0}<1 1 0> substrates with Jc=10 3 A/cm 2 using this method with our device. The method is very promising in terms of its precise control of metal compositions, high deposition rate and low cost non-vacuum approach. Improvements of this technique are being carried out to fabricate long YBCO tapes.

  14. Trapped Field Characteristics of Stacked YBCO Thin Plates for Compact NMR Magnets: Spatial Field Distribution and Temporal Stability.

    PubMed

    Hahn, Seungyong; Kim, Seok Beom; Ahn, Min Cheol; Voccio, John; Bascuñán, Juan; Iwasa, Yukikazu

    2010-06-01

    This paper presents experimental and analytical results of trapped field characteristics of a stack of square YBCO thin film plates for compact NMR magnets. Each YBCO plate, 40 mm × 40 mm × 0.08 mm, has a 25-mm diameter hole at its center. A total of 500 stacked plates were used to build a 40-mm long magnet. Its trapped field, in a bath of liquid nitrogen, was measured for spatial field distribution and temporal stability. Comparison of measured and analytical results is presented: the effects on trapped field characteristics of the unsaturated nickel substrate and the non-uniform current distribution in the YBCO plate are discussed.

  15. Ceramic fiber ceramic matrix filter development

    SciTech Connect

    Judkins, R.R.; Stinton, D.P.; Smith, R.G.; Fischer, E.M.

    1994-09-01

    The objectives of this project were to develop a novel type of candle filter based on a ceramic fiber-ceramic matrix composite material, and to extend the development to full-size, 60-mm OD by 1-meter-long candle filters. The goal is to develop a ceramic filter suitable for use in a variety of fossil energy system environments such as integrated coal gasification combined cycles (IGCC), pressurized fluidized-bed combustion (PFBC), and other advanced coal combustion environments. Further, the ceramic fiber ceramic matrix composite filter, hereinafter referred to as the ceramic composite filter, was to be inherently crack resistant, a property not found in conventional monolithic ceramic candle filters, such as those fabricated from clay-bonded silicon carbide. Finally, the adequacy of the filters in the fossil energy system environments is to be proven through simulated and in-plant tests.

  16. Development of YBCO Superconductor for Electric Systems: Cooperative Research and Development Final Report, CRADA Number CRD-04-150

    SciTech Connect

    Bhattacharya, R.

    2013-03-01

    The proposed project will be collaborative in exploration of high temperature superconductor oxide films between SuperPower, Inc. and the National Renewable Energy Laboratory. This CRADA will attempt to develop YBCO based high temperature oxide technology.

  17. polycrystalline ceramics

    NASA Astrophysics Data System (ADS)

    Cai, Yunqi; Ma, Ji; Cui, Qi; Wang, Wenzhang; Zhang, Hui; Chen, Qingming

    2014-12-01

    La2/3Ca1/3MnO3 polycrystalline ceramics were synthesized by sol-gel method. Sharp temperature coefficient of resistance (TCR) variation (with peak value up to 22 %) has been observed near the metal-insulator transition temperature T MI (273 K) for the sample sintered at 1,450 °C. This TCR value is much higher than the previously reported values for the undoped and Ag-doped La0.67Ca0.33MnO3 samples and is comparable to the optimized thin films. It was concluded that the improved physical properties of the La0.67Ca0.33MnO3 material are due to its improved microstructure and homogeneity.

  18. Gas Separations using Ceramic Membranes

    SciTech Connect

    Paul KT Liu

    2005-01-13

    This project has been oriented toward the development of a commercially viable ceramic membrane for high temperature gas separations. A technically and commercially viable high temperature gas separation membrane and process has been developed under this project. The lab and field tests have demonstrated the operational stability, both performance and material, of the gas separation thin film, deposited upon the ceramic membrane developed. This performance reliability is built upon the ceramic membrane developed under this project as a substrate for elevated temperature operation. A comprehensive product development approach has been taken to produce an economically viable ceramic substrate, gas selective thin film and the module required to house the innovative membranes for the elevated temperature operation. Field tests have been performed to demonstrate the technical and commercial viability for (i) energy and water recovery from boiler flue gases, and (ii) hydrogen recovery from refinery waste streams using the membrane/module product developed under this project. Active commercializations effort teaming with key industrial OEMs and end users is currently underway for these applications. In addition, the gas separation membrane developed under this project has demonstrated its economical viability for the CO2 removal from subquality natural gas and landfill gas, although performance stability at the elevated temperature remains to be confirmed in the field.

  19. Effect of Al and Ca co-doping, in the presence of Te, in superconducting YBCO whiskers growth.

    PubMed

    Pascale, Lise; Truccato, Marco; Operti, Lorenza; Agostino, Angelo

    2016-10-01

    High-Tc superconducting cuprates (HTSC) such as YBa2Cu3O7 - x (YBCO) are promising candidates for solid-state THz applications based on stacks of intrinsic Josephson junctions (IJJs) with atomic thickness. In view of future exploitation of IJJs, high-quality superconducting YBCO tape-like single crystals (whiskers) have been synthesized from Ca-Al-doped precursors in the presence of Te. The main aim of this paper is to determine the importance of the simultaneous use of Al, Te and Ca in promoting YBCO whiskers growth with good superconducting properties (Tc = 79-84 K). Further, single-crystal X-ray diffraction (SC-XRD) refinements of tetragonal YBCO whiskers (P4/mmm) are reported to fill the literature lack of YBCO structure investigations. All the as-grown whiskers have also been investigated by means of X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Our results demonstrate that the interplay of Ca, Te and Al elements is clearly necessary in order to obtain superconducting YBCO whiskers. The data obtained from SC-XRD analyses confirm the highly crystalline nature of the whiskers grown. Ca and Al enter the structure by replacing the Y and the octahedral coordinated Cu1 site, respectively, as in other similar orthorhombic compounds, while Te does not enter the structure of whiskers but its presence in the precursor is essential to the growth of the crystals.

  20. Crystallinity of YBCO thin films on an MgO substrate using an amorphous buffer layer deposited at a low temperature

    NASA Astrophysics Data System (ADS)

    Nakamura, Y.; Kudo, S.; Mukaida, M.; Ohshima, S.

    2002-10-01

    We have investigated crystallinity of YBCO films on an MgO substrate using an amorphous buffer layer. The evaluated films are obtained as follows: an amorphous YBCO buffer layer is deposited on the MgO substrate at a low temperature (200 °C); and then, an amorphous buffer layer is crystallized by the thermal annealing at a high temperature from 910 to 1030 °C; finally, main YBCO film is grown on the crystalline YBCO buffer layer over the MgO substrate. A significant improvement in the crystalline quality of the YBCO films was achieved, when amorphous buffer layers of 100 nm in thickness were crystallized by annealing temperature 950 °C and then annealing is continued for 1 h in air atmosphere. We confirmed that YBCO films grown on a well-crystallized buffer layer had better crystallinity than ones on bare MgO substrate, which has substantially large lattice mismatch.

  1. Ceramic inspection system

    DOEpatents

    Werve, Michael E.

    2006-05-16

    A system for inspecting a ceramic component. The ceramic component is positioned on a first rotary table. The first rotary table rotates the ceramic component. Light is directed toward the first rotary table and the rotating ceramic component. A detector is located on a second rotary table. The second rotary table is operably connected to the first rotary table and the rotating ceramic component. The second rotary table is used to move the detector at an angle to the first rotary table and the rotating ceramic component.

  2. Dental ceramics: An update

    PubMed Central

    Shenoy, Arvind; Shenoy, Nina

    2010-01-01

    In the last few decades, there have been tremendous advances in the mechanical properties and methods of fabrication of ceramic materials. While porcelain-based materials are still a major component of the market, there have been moves to replace metal ceramics systems with all ceramic systems. Advances in bonding techniques have increased the range and scope for use of ceramics in dentistry. In this brief review, we will discuss advances in ceramic materials and fabrication techniques. Examples of the microstructure property relationships for these ceramic materials will also be addressed. PMID:21217946

  3. The Effects of Grain Boundaries on the Current Transport Properties in YBCO-Coated Conductors.

    PubMed

    Yang, Chao; Xia, Yudong; Xue, Yan; Zhang, Fei; Tao, Bowan; Xiong, Jie

    2015-12-01

    We report a detailed study of the grain orientations and grain boundary (GB) networks in Y2O3 films grown on Ni-5 at.%W substrates. Electron back scatter diffraction (EBSD) exhibited different GB misorientation angle distributions, strongly decided by Y2O3 films with different textures. The subsequent yttria-stabilized zirconia (YSZ) barrier and CeO2 cap layer were deposited on Y2O3 layers by radio frequency sputtering, and YBa2Cu3O7-δ (YBCO) films were deposited by pulsed laser deposition. For explicating the effects of the grain boundaries on the current carry capacity of YBCO films, a percolation model was proposed to calculate the critical current density (J c) which depended on different GB misorientation angle distributions. The significantly higher J c for the sample with sharper texture is believed to be attributed to improved GB misorientation angle distributions.

  4. Feasibility of large-current capacity YBCO conductors with on-demand transposition

    NASA Astrophysics Data System (ADS)

    Yanagi, Nagato; Mito, Toshiyuki; Noguchi, Hiroki; Terazaki, Yoshiro; Tamura, Hitoshi; Iwakuma, Masataka; Aoki, Yuji; Izumi, Teruo; Shiohara, Yuh

    We propose a new idea for fabricating a large-current capacity YBCO conductor having a Roebel-type transposition formed by joining tapes. If the joule heating generated by joints is smaller than other heat sources, such as AC losses, this type of conductor may work as a quasi-superconductor. We note that the Roebel-type transposition can be included on demand in coil windings, not over the whole conductor length but rather locally, such as at terminals and coil edges to secure uniform current distribution among tapes. We fabricated a 1.2 m-long conductor sample based on this idea using 20 YBCO tapes. The Roebel-assembled tapes having joints with a 600-mm pitch length for meandering were imbedded in a copper jacket and soldered. The sample was tested in liquid nitrogen under the self magnetic field and the critical current was measured. The joint resistance was evaluated and compared with the expected value.

  5. Theoretical analysis of a YBCO squirrel-cage type induction motor based on an equivalent circuit

    NASA Astrophysics Data System (ADS)

    Morita, G.; Nakamura, T.; Muta, I.

    2006-06-01

    A HTS induction motor, with a HTS squirrel-cage rotor, is analysed using an electrical equivalent circuit. The squirrel-cage winding in the rotor consists of rotor bars and end rings, and both are considered to be made of YBCO film conductors. A wide range of electric field versus current density in YBCO film is formulated based on the Weibull function, and analysed as a non-linear resistance in the equivalent circuit. It is shown that starting and accelerating torques of the HTS induction motor are improved drastically compared to those of a conventional induction motor. Furthermore, large synchronous torque can also be realized by trapping the magnetic flux in the rotor circuit because of the persistent current mode.

  6. Microstructure of YBCO thin films prepared by TFA-MOD method

    NASA Astrophysics Data System (ADS)

    Nagino, I.; Matsumoto, K.; Adachi, H.; Miyata, S.; Yoshizumi, M.; Izumi, T.; Shiohara, Y.

    2010-11-01

    The microstructure of the recently developed coated conductors was investigated by using electron back scatter diffraction pattern (EBSP). We prepared TFA (trifluoroacetates)-MOD (metal organic deposition) derived YBa2Cu3O7-x (YBCO) films on CeO2/LaMnO3/IBAD-MgO/Gd2Zr2O7/Hastelloy C276 substrates of 1 cm-width. The EBSP observation showed that there was a difference of surface microstructure between the midsection and the end of TFA-MOD YBCO film layer in the direction of width. This is attributed not to the local difference of the biaxial texture of CeO2 top layer but to the local difference of growth condition during TFA-MOD process.

  7. Study of microstructure and electrical properties of bulk YBCO prepared by melt textured growth technique

    SciTech Connect

    Gonal, M. R.; Krishnan, Madangopal; Tewari, R.; Tyagi, A. K.; Gyore, A.; Vajda, I.

    2015-06-24

    Bulk YBCO components were prepared using Melt Texture Growth (MTG) technique. Components were fabricated using MTG by addition of Y{sub 2}BaCuO{sub 5} (Y211) and Ag to YBCO, which leads to improved grain size without affecting superconducting properties. Green compacts prepared by cold isostatic pressing were pre-sintered at 930°C before subjecting melt texturing. Cooling rates lower than 1 °C.h{sup −1} was used, in between (peritectic) temperature of about 995 and 1025°C, to obtain large grained components. Microstructure studies in details were carried out by Scanning Electron Microscope (SEM), Electron Probe Micro Analysis (EPMA), Orientation Imaging Microscope (OIM) and TEM correlated with electrical properties like Critical current density (J{sub c})

  8. Magnetization of YBCO film with ac travelling magnetic waves of relatively short wavelengths

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Coombs, Tim

    2017-02-01

    The magnetizations of the YBCO film with ac travelling magnetic waves of relatively short wavelengths were studied. The results have verified that the reported "intermediate value" of the superconducting current density [Wang et al., Appl. Phys. Lett. 104(3), 032602 (2014)] was caused by the existence of multiple transition regions in the sample: the magnetic poles induce ±JC in the pole regions, which produces two transition regions within each wavelength λ ( +JC→-JC→+JC , and vice versa, while the symbol → indicates the transition region). The current densities in the transition region are with intermediate values, which are smaller than the critical value. In case of relatively short wavelength, there are multiple transition regions, which occupy a large fraction of the YBCO sample with intermediate current values. Moreover, the wavelike current distributions might help explain the flux transportation and dc output voltage in HTS flux pump.

  9. Improved noise performance of ultrathin YBCO Dayem bridge nanoSQUIDs

    NASA Astrophysics Data System (ADS)

    Arpaia, R.; Arzeo, M.; Baghdadi, R.; Trabaldo, E.; Lombardi, F.; Bauch, T.

    2017-01-01

    We have fabricated YBa2Cu3O{}7-δ (YBCO) nano superconducting quantum interference devices (nanoSQUIDs), realized in Dayem bridge configuration, on films with thickness down to 10 nm. The devices, which have not been protected by a Au capping layer during the nanopatterning, show modulations of the critical current as a function of the externally applied magnetic field from 300 mK up to the critical temperature of the nanobridges. The absence of the Au shunting layer and the enhancement of the sheet resistance in ultrathin films lead to very large voltage modulations and transfer functions, which make these nanoSQUIDs highly sensitive devices. Indeed, by using bare YBCO nanostructures, we have revealed an upper limit for the intrinsic white flux noise level {S}{{Φ },{{w}}}1/2\\lt 450 {{n}}{{{Φ }}}0 {{Hz}}-1/2.

  10. Method for adhesion of metal films to ceramics

    DOEpatents

    Lowndes, D.H.; Pedraza, A.J.; DeSilva, M.J.; Kumar, R.A.

    1997-12-30

    Methods for making strongly bonded metal-ceramic materials are disclosed. The methods include irradiating a portion of the surface of the ceramic material with a pulsed ultraviolet laser having an energy density sufficient to effect activation of the irradiated surface of the ceramic material so that adhesion of metals subsequently deposited onto the irradiated surface is substantially increased. Advantages of the invention include (i) the need for only a small number of laser pulses at relatively low focused energy density, (ii) a smoother substrate surface, (iii) activation of the laser-treated surface which provides a chemical bond between the surface and a metal deposited thereon, (iv) only low temperature annealing is required to produce the strong metal-ceramic bond; (v) the ability to obtain strong adhesion between ceramic materials and oxidation resistant metals; (vi) ability to store the laser treated ceramic materials for later deposition of metals thereon. 7 figs.

  11. Method for adhesion of metal films to ceramics

    DOEpatents

    Lowndes, Douglas H.; Pedraza, Anthony J.; DeSilva, Melvin J.; Kumar, Rajagopalan A.

    1997-01-01

    Methods for making strongly bonded metal-ceramic materials. The methods include irradiating a portion of the surface of the ceramic material with a pulsed ultraviolet laser having an energy density sufficient to effect activation of the irradiated surface of the ceramic material so that adhesion of metals subsequently deposited onto the irradiated surface is substantially increased. Advantages of the invention include (i) the need for only a small number of laser pulses at relatively low focused energy density, (ii) a smoother substrate surface, (iii) activation of the laser-treated surface which provides a chemical bond between the surface and a metal deposited thereon, (iv) only low temperature annealing is required to produce the strong metal-ceramic bond; (v) the ability to obtain strong adhesion between ceramic materials and oxidation resistant metals; (vi) ability to store the laser treated ceramic materials for later deposition of metals thereon.

  12. Design of a Cryogen Free Cryo-flipper using a High Tc YBCO Film

    NASA Astrophysics Data System (ADS)

    Parnell, S. R.; Kaiser, H.; Washington, A. L.; Li, F.; Wang, T.; Baxter, D. V.; Pynn, R.

    It is well-known that the Meissner effect in superconducting materials can be used to provide a well-defined non- adiabatic magnetic field transition that can be utilised to produce an efficient white beam neutron spin flipper. Typically these devices utilise niobium and hence require continuous use of liquid helium in order to maintain the device tem- perature. The use of high Tc materials removes the need for cryogens and has been explored previously and shown to provide efficient flipping of the neutron spin. Improvements in thin high Tc films over the past few years make these materials even more attractive. Here we present a design using a 350-nm-thick YBCO film capped with 100 nm of gold on a 78 x 100 x 0.5 mm sapphire substrate (Theva, Germany). The apparatus is compact (200 mm in length along the neutron beam), consisting of an oxygen-free high-conductivity copper frame, which holds the YBCO film and is mounted to the cold finger of a closed-cycle refrigerator. The part of the vacuum chamber, where the YBCO film is located, is ≈ 50 mm wide, which allows us to minimise the distance from the film to the external magnets. This distance is 26 mm on each side. The details of the guide field design are also discussed. In this design, the maximum neutron beam size that can be used is 40 × 40 mm2 and we can easily switch from a vertical to a horizontal guide field on either side of the YBCO film.

  13. Fishtail Effect Due To Silver Influenced Sub-precipitate Microstructure in YBCO/Ag Superconducting Composites

    NASA Astrophysics Data System (ADS)

    Parthasarathy, R.; Kumar, N. Devendra; Bai, V. Seshu

    2011-07-01

    We report the existence of a sub-precipitate microstructure and the resulting fishtail effect in YBCO/Ag superconducting composites fabricated by Seeded Infiltration and Growth Processing. The SEM micrographs reveal sub-precipitate microstructure in the form of precipitates of size less than 100 nm within the larger non-superconducting Y-211 precipitates that contributes to the enhancement of Jc in the form of secondary peak effect at lower fields.

  14. Epitaxial growth of YBCO films on metallic substrates buffered with yttria-stabilized zirconia

    NASA Astrophysics Data System (ADS)

    Ma, B.; Li, M.; Fisher, B. L.; Koritala, R. E.; Balachandran, U.

    2002-05-01

    Biaxially textured yttria-stabilized zirconia (YSZ) films were grown on polished Hastelloy C (HC) substrates by ion-beam-assisted deposition (IBAD) and electron-beam evaporation. A water-cooled sample stage was used to dissipate heat generated by the Kaufman ion source and to maintain the substrate temperature below 100 °C during deposition. X-ray pole figures were used for texture analysis. In-plane texture measured from the YSZ (111) φ-scan full-width-at-half-maximum (FWHM) was 13.2° and out-of-plane texture from the YSZ (002) ω-scan FWHM was 7.7°. In-plane texture improved with lowered substrate temperature during IBAD deposition. RMS surface roughness of 3.3 nm was measured by atomic force microscopy. A thin CeO2 buffer layer (≈10 nm) was deposited to improve the lattice match between the YSZ and YBCO films and to enhance the biaxial alignment of YBCO films. YBCO films were epitaxially grown on IBAD-YSZ buffered HC substrates with and without CeO2 buffer layers by pulsed laser deposition (PLD). In-plane texture FWHMs of 12° and 9° were observed for CeO2 (111) and YBCO (103), respectively. Tc=90 K, with sharp transition, and Jc values of ≈2×106 A/cm2 at 77 K in zero field were observed on 0.5-μm-thick, 5-mm-wide, and 1-cm-long samples.

  15. Development of Solution Buffer Layers for RABiTS Based YBCO Coated Conductors

    SciTech Connect

    Paranthaman, Mariappan Parans; Qiu, Xiaofeng; List III, Frederick Alyious; Zhang, Yifei; Li, Xiaoping; Sathyamurthy, Srivatsan; Thieme, C. L. H.; Rupich, M. W.

    2011-01-01

    Abstract The main objective of this research is to find a suitable alternate solution based seed layer for the standard RABiTS three-layer architecture of physical vapor deposited CeO cap/YSZ barrier/Y O seed on Ni-5%W metal tape. In the present work, we have identified CeO buffer layer as a potential replacement for Y O seeds. Using a metal-organic deposition (MOD) process, we have grown smooth, crack-free, epitaxial thin films of CeO (pure and Zr, Cu and Gd-doped) directly on biaxially textured Ni-5W substrates in short lengths. Detailed XRD studies indicate that a single epitaxial CeO phase with slightly improved out-of-plane texture compared to the texture of the underlying Ni-W substrates can be achieved in pure, undoped CeO samples. We have also demonstrated the growth of YSZ barrier layers on pure CeO seeds using sputtering. Both sputtered CeO cap layers and MOD-YBCO films were grown epitaxially on these YSZ-buffered MOD-CeO /Ni-5W substrates. High critical currents per unit width, of 264 A/cm (critical current density, of 3.3 MA/cm ) at 77 K and 0.01 T was achieved for 0.8 m thick MOD-YBCO films grown on MOD-CeO seeds. These results indicate that CeO films can be grown directly on Ni-5W substrates and still support high performance YBCO coated conductors. This work holds promise for a route for producing low-cost buffer architecture for RABiTS based YBCO coated conductors.

  16. Ceramic electrolyte coating methods

    DOEpatents

    Seabaugh, Matthew M.; Swartz, Scott L.; Dawson, William J.; McCormick, Buddy E.

    2004-10-12

    Processes for preparing aqueous suspensions of a nanoscale ceramic electrolyte material such as yttrium-stabilized zirconia. The invention also includes a process for preparing an aqueous coating slurry of a nanoscale ceramic electrolyte material. The invention further includes a process for depositing an aqueous spray coating slurry including a ceramic electrolyte material on pre-sintered, partially sintered, and unsintered ceramic substrates and products made by this process.

  17. Effect of Au nano-particles doping on polycrystalline YBCO high temperature superconductor

    NASA Astrophysics Data System (ADS)

    Dadras, Sedigheh; Gharehgazloo, Zahra

    2016-07-01

    In this research, we prepared different Au nanoparticles (0.1-2 wt%) doped YBCO high temperature superconductor samples by sol-gel method. To characterize the samples, we used X-Ray diffraction (XRD) and scanning electron microscope (SEM) analysis. Results show the formation of orthorhombic phase of superconductivity for all prepared samples. We observed that by adding Au nanoparticles, the grains' size of the samples reduces from 76 nm to 47 nm as well. The critical current density (Jc) and transition temperature (Tc) were determined using current versus voltage (I-V) and resistivity versus temperature (ρ-T) measurements, respectively. We found that by increasing Au nanoparticles in the compound, in comparison to the pure YBCO sample, the transition temperature, pinning energy and critical current density will increase. Also, the highest Jc is for 1 wt% Au doped YBCO compound that its critical current density is about 8 times more than the Jc of pure one in 0.7 T magnetic field.

  18. Field Performance of an Optimized Stack of YBCO Square "Annuli" for a Compact NMR Magnet.

    PubMed

    Hahn, Seungyong; Voccio, John; Bermond, Stéphane; Park, Dong-Keun; Bascuñán, Juan; Kim, Seok-Beom; Masaru, Tomita; Iwasa, Yukikazu

    2011-06-01

    The spatial field homogeneity and time stability of a trapped field generated by a stack of YBCO square plates with a center hole (square "annuli") was investigated. By optimizing stacking of magnetized square annuli, we aim to construct a compact NMR magnet. The stacked magnet consists of 750 thin YBCO plates, each 40-mm square and 80- μm thick with a 25-mm bore, and has a Ø10 mm room-temperature access for NMR measurement. To improve spatial field homogeneity of the 750-plate stack (YP750) a three-step optimization was performed: 1) statistical selection of best plates from supply plates; 2) field homogeneity measurement of multi-plate modules; and 3) optimal assembly of the modules to maximize field homogeneity. In this paper, we present analytical and experimental results of field homogeneity and temporal stability at 77 K, performed on YP750 and those of a hybrid stack, YPB750, in which two YBCO bulk annuli, each Ø46 mm and 16-mm thick with a 25-mm bore, are added to YP750, one at the top and the other at the bottom.

  19. Ultrasonic signatures at the superconducting and the pseudogap phase boundaries in YBCO cuprates.

    SciTech Connect

    Shehter, Arkady; Migliori, Albert; Betts, Jonathan B.; Balakirev, Fedor F.; McDonald, Ross David; Riggs, Scott C.; Ramshaw, Brad; Liang, Ruixing; Hardy, Walter N.; Bonn, Doug A.

    2012-08-28

    A major issue in the understanding of cuprate superconductors is the nature of the metallic state from which high temperature superconductivity emerges. Central to this issue is the pseudogap region of the doping-temperature phase diagram that extends from room temperature to the superconducting transition. Although polarized neutron scattering studies hint at magnetic order associated with the pseudogap, there is no clear thermodynamic evidence for a phase boundary. Such evidence has a straightforward physical interpretation, however, it is difficult to obtain over a temperature range wide enough to encompass both the pseudogap and superconducting phases. We address this by measuring the elastic response of detwinned single crystals, an underdoped YBCO{sub 6.60} with superconducting transition at T{sub c} = 61.6K and a slightly overdoped YBCO{sub 6.98} with T{sub c} = 88.0K. We observe a discontinuity in the elastic moduli across the superconducting transition. Its magnitude requires that pair formation is coincident with superconducting coherence (the onset of the Meissner effect). For both crystals the elastic response reveals a phase transition at the pseudogap boundary. In slightly overdoped YBCO that transition is 20K below T{sub c}, extending the pseudogap phase boundary inside the superconducting dome. This supports a description of the metallic state in cuprates where a pseudogap phase boundary evolves into a quantum critical point masked by the superconducting dome.

  20. Flux pinning by Al-based nanoparticles embedded in YBCO: A transmission electron microscopic study

    NASA Astrophysics Data System (ADS)

    Ben Azzouz, F.; Zouaoui, M.; Mellekh, A.; Annabi, M.; Van Tendeloo, G.; Ben Salem, M.

    2007-05-01

    A series of YBa2Cu3Oy (YBCO) samples with small amounts (0-0.6 wt.%) of nanosized alumina particles (50 nm) are synthesized in air by solid state reaction. The microstructure has been characterized by transmission electron microscopy (TEM) and the critical current density Jc has been measured by the standard four-probe method in the applied magnetic field at 77 K. TEM and energy dispersive X-ray spectroscopy (EDS) analysis have shown that alumina reacts with the YBCO matrix to form nanometric aluminium-rich inhomogeneities intergrown within the YBCO superconducting matrix. These inhomogeneities reduce the onset transition temperature Tconset and the zero resistance temperature Tc. In spite of the monotonic decrease of the superconducting temperature Tc with increasing alumina addition, the Jc(H) behaviour is remarkably improved. The characteristic behaviour of Jc can be explained in terms of the counterbalance of two effects simultaneously caused by the nanometric alumina addition in the system. One effect is the formation of the Al-rich nanometric inhomogeneities relevant for the flux pinning, and the other effect is the reduction of matrix superconducting volume, which is reflected by a decrease of the critical current density Jc at zero applied magnetic field.

  1. Bulk YBCO seeded with 45°-45° bridge-seeds of different lengths

    NASA Astrophysics Data System (ADS)

    Shi, Y.-H.; Durrell, J. H.; Dennis, A. R.; Cardwell, D. A.

    2013-01-01

    Single grain, (RE)BCO (rare earth-barium-copper oxide) bulk superconductors in large or complicated geometries are required for a variety of potential applications, such as in motors and generators and magnetic shielding devices. As a result, top, multi-seeded, melt growth has been investigated over the past 15 years in an attempt to enlarge the size of (RE)BCO single grains specifically for such applications. Of these multi-seeding techniques, so-called bridge-seeding provides the best alignment of two seeds in a single grain growth process. Here we report, for the first time, the successful growth of YBCO (yttrium-barium-copper oxide) using a special, 45°-45°, arrangement of bridge-seeds. The superconducting properties, including trapped field, of the multi-seeded YBCO grains have been measured for different bridge lengths of the 45°-45° bridge-seeds. The boundaries at the impinging growth front and the growth features of the top, multi-seeded surface and cross-section of the multi-seeded, samples have been analysed using optical microscopy. The results suggest that an impurity-free boundary between the two seeds of each leg of the bridge-seed can form when 45°-45° bridge-seeds are used to enlarge the size of YBCO grains.

  2. Iron-YBCO heterostructures and their application for trapped field superconducting motor

    NASA Astrophysics Data System (ADS)

    Granados, X.; Bartolomé, E.; Obradors, X.; Tornes, M.; Rodrigues, L.; Gawalek, W.; McCulloch, M.; Dew Hughes, D.; Campbell, A.; Coombs, T.; Ausloos, M.; Cloots, R.

    2006-06-01

    In this work we report on the magnetic behavior of the heterostructures formed by bulk based YBCO rings and ferromagnetic yoke. The magnetization cycle has been performed by an In-Field Hall Mapping technique. A video-like recording of the magnetization process makes it possible to obtain the magnetization of selected areas. The current flowing through the superconducting rings can be deduced from the magnetic field maps. The displacement of the peak of magnetization due to the flux reversal produced by the magnetization of the yoke is also considered. These hybrid heterostructures formed by ferromagnetic and superconducting material have been applied in the construction of the rotor for a brushless AC motor. The design and construction of this machine was carried out within the framework of the TMR Network SUPERMACHINES. The rotor has been designed in a quadrupolar configuration by cutting large YBCO ''window frames'' from seeded melt-textured single domain YBCO pellets. This rotor has been coupled to a conventional stator of copper coils wound on an iron armature. The stator can be excited both in bipolar or quadrupolar mode. We report on the behaviour of the motor after a field cooling process when excited in quadrupolar mode.

  3. Advanced Ceramic Armor Materials

    DTIC Science & Technology

    1990-05-11

    materials, toughened alumina, fiber -reinforced glass matrix composites, and multilayer-gradient materials for ballistic testing. Fabrication and...material systems: Multilayer advanced armor materials consisting of a hard ceramic faceplate bonded to a graphite fiber -reinforced glass matrix...toughened alumina, and fiber - applied studies of advanced reinforced ceramic matrix glass and glass -ceramic composites for ballistic testing. technologies

  4. Brittleness of ceramics

    NASA Technical Reports Server (NTRS)

    Kroupa, F.

    1984-01-01

    The main characteristics of mechanical properties of ceramics are summarized and the causes of their brittleness, especially the limited mobility of dislocations, are discussed. The possibility of improving the fracture toughness of ceramics and the basic research needs relating to technology, structure and mechanical properties of ceramics are stressed in connection with their possible applications in engineering at high temperature.

  5. Ceramic to metal seal

    DOEpatents

    Snow, Gary S.; Wilcox, Paul D.

    1976-01-01

    Providing a high strength, hermetic ceramic to metal seal by essentially heating a wire-like metal gasket and a ceramic member, which have been chemically cleaned, while simultaneously deforming from about 50 to 95 percent the metal gasket against the ceramic member at a temperature of about 30 to 75 percent of the melting temperature of the metal gasket.

  6. Ceramic gas turbine shroud

    SciTech Connect

    Shi, Jun; Green, Kevin E.

    2014-07-22

    An example gas turbine engine shroud includes a first annular ceramic wall having an inner side for resisting high temperature turbine engine gasses and an outer side with a plurality of radial slots. A second annular metallic wall is positioned radially outwardly of and enclosing the first annular ceramic wall and has a plurality of tabs in communication with the slot of the first annular ceramic wall. The tabs of the second annular metallic wall and slots of the first annular ceramic wall are in communication such that the first annular ceramic wall and second annular metallic wall are affixed.

  7. Thin film ceramic thermocouples

    NASA Technical Reports Server (NTRS)

    Gregory, Otto (Inventor); Fralick, Gustave (Inventor); Wrbanek, John (Inventor); You, Tao (Inventor)

    2011-01-01

    A thin film ceramic thermocouple (10) having two ceramic thermocouple (12, 14) that are in contact with each other in at least on point to form a junction, and wherein each element was prepared in a different oxygen/nitrogen/argon plasma. Since each element is prepared under different plasma conditions, they have different electrical conductivity and different charge carrier concentration. The thin film thermocouple (10) can be transparent. A versatile ceramic sensor system having an RTD heat flux sensor can be combined with a thermocouple and a strain sensor to yield a multifunctional ceramic sensor array. The transparent ceramic temperature sensor that could ultimately be used for calibration of optical sensors.

  8. Rapid and semi-analytical design and simulation of a toroidal magnet made with YBCO and MgB2 superconductors

    DOE PAGES

    Dimitrov, I. K.; Zhang, X.; Solovyov, V. F.; ...

    2015-07-07

    Recent advances in second-generation (YBCO) high-temperature superconducting wire could potentially enable the design of super high performance energy storage devices that combine the high energy density of chemical storage with the high power of superconducting magnetic storage. However, the high aspect ratio and the considerable filament size of these wires require the concomitant development of dedicated optimization methods that account for the critical current density in type-II superconductors. In this study, we report on the novel application and results of a CPU-efficient semianalytical computer code based on the Radia 3-D magnetostatics software package. Our algorithm is used to simulate andmore » optimize the energy density of a superconducting magnetic energy storage device model, based on design constraints, such as overall size and number of coils. The rapid performance of the code is pivoted on analytical calculations of the magnetic field based on an efficient implementation of the Biot-Savart law for a large variety of 3-D “base” geometries in the Radia package. The significantly reduced CPU time and simple data input in conjunction with the consideration of realistic input variables, such as material-specific, temperature, and magnetic-field-dependent critical current densities, have enabled the Radia-based algorithm to outperform finite-element approaches in CPU time at the same accuracy levels. Comparative simulations of MgB2 and YBCO-based devices are performed at 4.2 K, in order to ascertain the realistic efficiency of the design configurations.« less

  9. Rapid and semi-analytical design and simulation of a toroidal magnet made with YBCO and MgB2 superconductors

    SciTech Connect

    Dimitrov, I. K.; Zhang, X.; Solovyov, V. F.; Chubar, O.; Li, Qiang

    2015-07-07

    Recent advances in second-generation (YBCO) high-temperature superconducting wire could potentially enable the design of super high performance energy storage devices that combine the high energy density of chemical storage with the high power of superconducting magnetic storage. However, the high aspect ratio and the considerable filament size of these wires require the concomitant development of dedicated optimization methods that account for the critical current density in type-II superconductors. In this study, we report on the novel application and results of a CPU-efficient semianalytical computer code based on the Radia 3-D magnetostatics software package. Our algorithm is used to simulate and optimize the energy density of a superconducting magnetic energy storage device model, based on design constraints, such as overall size and number of coils. The rapid performance of the code is pivoted on analytical calculations of the magnetic field based on an efficient implementation of the Biot-Savart law for a large variety of 3-D “base” geometries in the Radia package. The significantly reduced CPU time and simple data input in conjunction with the consideration of realistic input variables, such as material-specific, temperature, and magnetic-field-dependent critical current densities, have enabled the Radia-based algorithm to outperform finite-element approaches in CPU time at the same accuracy levels. Comparative simulations of MgB2 and YBCO-based devices are performed at 4.2 K, in order to ascertain the realistic efficiency of the design configurations.

  10. All-ceramic crowns.

    PubMed

    Lehner, C R; Schärer, P

    1992-06-01

    Despite the good appearance and biocompatibility of dental porcelains, failures are still of considerable concern because of some limited properties common to all-ceramic crown systems. As in the years before, pertinent scientific articles published between November 1990 and December 1991 focused on strengthening mechanisms and compared fracture toughness for different ceramic systems by using various test methods. Some evaluated the clinical implications thereon for seating and loading crowns and measured wear against different ceramic surface conditions. Recently introduced with pleasing aesthetic qualities, IPS-Empress (Ivoclar, Schaan, Liechtenstein), a new European leucite-reinforced glass-ceramic, has finally drawn attention in some journals and has been reviewed with promising in vitro test results. Using a simple press-molding technique, well-fitting crowns, inlays, and veneers can be fabricated without an additional ceramming procedure. Again, only long-term clinical trials will validate achievements compared with other all-ceramic systems and with well-established metal ceramics.

  11. Real-time observation of the melting process of YBCO thin film on MgO substrate

    NASA Astrophysics Data System (ADS)

    J, Hu; X, Yao; L, Rao Q.

    2003-11-01

    In order to study the mechanism of the liquid phase hetero-epitaxial growth, the melting process of YBa2Cu3O7-dgr (YBCO) thin films was observed by high-temperature optical microscopy. During the heating from room temperature to a temperature above the YBCO peritectic temperature (Tp), we surprisingly find that the YBCO thin film with a MgO substrate can be substantially superheated above the Tp of the YBCO oxide (at least 50 °C) at a heating rate of 5 °C min-1. This is a novel superheating phenomenon involved in a peritectic reaction and an oxide material, which is different from one reported in systems of metals and their alloys. After the melting process, x-ray diffraction analysis was performed, which shows that Y2BaCuO5 (Y211) grains are in good alignment on the MgO substrate. The superheating mechanism of the YBCO oxide is discussed.

  12. Fracture Behavior of Ceramic Composites.

    DTIC Science & Technology

    1983-08-01

    AD-R158 810 FRACTURE BEHAVIOR OF CERAMIC COMPOSITES(U) MATERIALS i/i SCIENCES CORP SPRING HOUSE PH K W BUESKING ET AL. AUG 83 MSC/TFR/’i482/i583...the U.S. Government . D T IC ELECTEF C01 AIR FORCE OFFICE OF SCIENTIFIC RESEARCH MSC TFR 1402/1503 Bolling Air Force Base, DC August, 1983 q Ippreved...Bethlehem Pike, Spring House , PA * 215-542-8400 ." -- . ". ’- , ,,- . ..O TTr.AqRTTpf SECURITY CLASSIFICATION OF THIS PAGE (When Date Enteredl REPORT

  13. Fracture Toughness Prediction for MWCNT Reinforced Ceramics

    SciTech Connect

    Henager, Charles H.; Nguyen, Ba Nghiep

    2013-09-01

    This report describes the development of a micromechanics model to predict fracture toughness of multiwall carbon nanotube (MWCNT) reinforced ceramic composites to guide future experimental work for this project. The modeling work described in this report includes (i) prediction of elastic properties, (ii) development of a mechanistic damage model accounting for matrix cracking to predict the composite nonlinear stress/strain response to tensile loading to failure, and (iii) application of this damage model in a modified boundary layer (MBL) analysis using ABAQUS to predict fracture toughness and crack resistance behavior (R-curves) for ceramic materials containing MWCNTs at various volume fractions.

  14. The friction and wear of ceramic/ceramic and ceramic/metal combinations in sliding contact

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E.; Dellacorte, Christopher

    1994-01-01

    The tribological characteristics of ceramics sliding on ceramics are compared to those of ceramics sliding on a nickel-based turbine alloy. The friction and wear of oxide ceramics and silicon-based ceramics in air at temperatures from room ambient to 900 C (in a few cases to 1200 C) were measured for a hemispherically-tipped pin on a flat sliding contact geometry. In general, especially at high temperature, friction and wear were lower for ceramic/metal combinations than for ceramic/ceramic combinations. The better tribological performance for ceramic/metal combinations is attributed primarily to the lubricious nature of the oxidized surface of the metal.

  15. The friction and wear of ceramic/ceramic and ceramic/metal combinations in sliding contact

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E.; Dellacorte, Christopher

    1993-01-01

    The tribological characteristics of ceramics sliding on ceramics are compared to those of ceramics sliding on a nickel based turbine alloy. The friction and wear of oxide ceramics and silicon-based ceramics in air at temperatures from room ambient to 900 C (in a few cases to 1200 C) were measured for a hemispherically-tipped pin on a flat sliding contact geometry. In general, especially at high temperature, friction and wear were lower for ceramic/metal combinations than for ceramic/ceramic combinations. The better tribological performance for ceramic/metal combinations is attributed primarily to the lubricious nature of the oxidized surface of the metal.

  16. Ceramic tamper-revealing seals

    DOEpatents

    Kupperman, David S.; Raptis, Apostolos C.; Sheen, Shuh-Haw

    1992-01-01

    A flexible metal or ceramic cable with composite ceramic ends, or a u-shaped ceramic connecting element attached to a binding element plate or block cast from alumina or zirconium, and connected to the connecting element by shrink fitting.

  17. Analyses of fine paste ceramics

    SciTech Connect

    Sabloff, J A

    1980-01-01

    Four chapters are included: history of Brookhaven fine paste ceramics project, chemical and mathematical procedures employed in Mayan fine paste ceramics project, and compositional and archaeological perspectives on the Mayan fine paste ceramics. (DLC)

  18. Ceramic laser materials

    NASA Astrophysics Data System (ADS)

    Ikesue, Akio; Aung, Yan Lin

    2008-12-01

    The word 'ceramics' is derived from the Greek keramos, meaning pottery and porcelain. The opaque and translucent cement and clay often used in tableware are not appropriate for optical applications because of the high content of optical scattering sources, that is, defects. Recently, scientists have shown that by eliminating the defects, a new, refined ceramic material - polycrystalline ceramic - can be produced. This advanced ceramic material offers practical laser generation and is anticipated to be a highly attractive alternative to conventional glass and single-crystal laser technologies in the future. Here we review the history of the development of ceramic lasers, the principle of laser generation based on this material, some typical results achieved with ceramic lasers so far, and discuss the potential future outlook for the field.

  19. NDE of ceramics and ceramic composites

    NASA Technical Reports Server (NTRS)

    Vary, Alex; Klima, Stanley J.

    1991-01-01

    Although nondestructive evaluation (NDE) techniques for ceramics are fairly well developed, they are difficult to apply in many cases for high probability detection of the minute flaws that can cause failure in monolithic ceramics. Conventional NDE techniques are available for monolithic and fiber reinforced ceramic matrix composites, but more exact quantitative techniques needed are still being investigated and developed. Needs range from flaw detection to below 100 micron levels in monolithic ceramics to global imaging of fiber architecture and matrix densification anomalies in ceramic composites. NDE techniques that will ultimately be applicable to production and quality control of ceramic structures are still emerging from the lab. Needs are different depending on the processing stage, fabrication method, and nature of the finished product. NDE techniques are being developed in concert with materials processing research where they can provide feedback information to processing development and quality improvement. NDE techniques also serve as research tools for materials characterization and for understanding failure processes, e.g., during thermomechanical testing.

  20. Development of improved processing and evaluation methods for high reliability structural ceramics for advanced heat engine applications Phase II. Final report

    SciTech Connect

    Pujari, V.J.; Tracey, D.M.; Foley, M.R.

    1996-02-01

    The research program had as goals the development and demonstration of significant improvements in processing methods, process controls, and nondestructive evaluation (NDE) which can be commercially implemented to produce high reliability silicon nitride components for advanced heat engine applications at temperatures to 1370{degrees}C. In Phase I of the program a process was developed that resulted in a silicon nitride - 4 w% yttria HIP`ed material (NCX 5102) that displayed unprecedented strength and reliability. An average tensile strength of 1 GPa and a strength distribution following a 3-parameter Weibull distribution were demonstrated by testing several hundred buttonhead tensile specimens. The Phase II program focused on the development of methodology for colloidal consolidation producing green microstructure which minimizes downstream process problems such as drying, shrinkage, cracking, and part distortion during densification. Furthermore, the program focused on the extension of the process to gas pressure sinterable (GPS) compositions. Excellent results were obtained for the HIP composition processed for minimal density gradients, both with respect to room-temperature strength and high-temperature creep resistance. Complex component fabricability of this material was demonstrated by producing engine-vane prototypes. Strength data for the GPS material (NCX-5400) suggest that it ranks very high relative to other silicon nitride materials in terms of tensile/flexure strength ratio, a measure of volume quality. This high quality was derived from the closed-loop colloidal process employed in the program.

  1. YBCO High-Temperature Superconducting Filters on M-Plane Sapphire Substrates

    NASA Technical Reports Server (NTRS)

    Sabataitis, J. C.; Mueller, C. H.; Miranda, F. A.; Warner, J.; Bhasin, K. B.

    1996-01-01

    Since the discovery of High Temperature Superconductors (HTS) in 1986, microwave circuits have been demonstrated using HTS films on various substrates. These HTS-based circuits have proven to operate with less power loss than their metallic film counterparts at 77 K. This translates into smaller and lighter microwave circuits for space communication systems such as multiplexer filter banks. High quality HTS films have conventionally been deposited on lanthanum aluminate (LaAlO3) substrates. However, LaAlO3 has a relative dielectric constant (epsilon(sub r)) of 24. With a epsilon(sub r) approx. 9.4-11.6, sapphire (Al2O3) would be a preferable substrate for the fabrication of HTS-based components since the lower dielectric constant would permit wider microstrip lines to be used in filter design, since the lower dielectric constant would permit wider microstrip lines to be used for a given characteristic impedance (Z(sub 0)), thus lowering the insertion losses and increasing the power handling capabilities of the devices. We report on the fabrication and characterization of YBa2Cu3O(7-delta) (YBCO) on M-plane sapphire bandpass filters at 4.0 GHz. For a YBCO 'hairpin' filter, a minimum insertion loss of 0.5 dB was measured at 77 K as compared with 1.4 dB for its gold counterpart. In an 'edge-coupled' configuration, the insertion loss went down from 0.9 dB for the gold film to 0.8 dB for the YBCO film at the same temperature.

  2. Continuous Fiber Ceramic Composites

    SciTech Connect

    2002-09-01

    Fiber-reinforced ceramic composites demonstrate the high-temperature stability of ceramics--with an increased fracture toughness resulting from the fiber reinforcement of the composite. The material optimization performed under the continuous fiber ceramic composites (CFCC) included a series of systematic optimizations. The overall goals were to define the processing window, to increase the robustinous of the process, to increase process yield while reducing costs, and to define the complexity of parts that could be fabricated.

  3. Displacive Transformation in Ceramics

    DTIC Science & Technology

    1994-02-28

    oxidizing atmosphere. In the fiber pullout mechanism of toughening which is thought to be the most powerful to date in ceramics, in non-graphite coated ...induced transformation of the ceramic coating promotes not only fiber pullout mechanisms, but also dissipates crack energy as well as causing frictional...1-11, (1971). 15 G. W. Taylor, "Electrical Properties of Niobium -Doped Ferroelectric Pb(Zr,SnTi)0 3 Ceramics," J. Appl. Phys., 38 [12], 4696-4706

  4. Effects of densification of precursor pellets on microstructures and critical current properties of YBCO melt-textured bulks

    NASA Astrophysics Data System (ADS)

    Setoyama, Yui; Shimoyama, Jun-ichi; Motoki, Takanori; Kishio, Kohji; Awaji, Satoshi; Kon, Koichi; Ichikawa, Naoki; Inamori, Satoshi; Naito, Kyogo

    2016-12-01

    Effects of densification of precursor disks on the density of residual voids and critical current properties for YBCO melt-textured bulk superconductors were systematically investigated. Six YBCO bulks were prepared from precursor pellets with different initial particle sizes of YBa2Cu3Oy (Y123) powder and applied pressures for pelletization. It was revealed that use of finer Y123 powder and consolidation using cold-isostatic-pressing (CIP) with higher pressures result in reduction of residual voids at inner regions of bulks and enhance Jc especially under low fields below the second peak.

  5. Alumina-based ceramic composite

    DOEpatents

    Alexander, Kathleen B.; Tiegs, Terry N.; Becher, Paul F.; Waters, Shirley B.

    1996-01-01

    An improved ceramic composite comprising oxide ceramic particulates, nonoxide ceramic particulates selected from the group consisting of carbides, borides, nitrides of silicon and transition metals and mixtures thereof, and a ductile binder selected from the group consisting of metallic, intermetallic alloys and mixtures thereof is described. The ceramic composite is made by blending powders of the ceramic particulates and the ductile to form a mixture and consolidating the mixture of under conditions of temperature and pressure sufficient to produce a densified ceramic composite.

  6. Measuring Fracture Times Of Ceramics

    NASA Technical Reports Server (NTRS)

    Shlichta, Paul J.; Bister, Leo; Bickler, Donald G.

    1989-01-01

    Electrical measurements complement or replace fast cinematography. Electronic system measures microsecond time intervals between impacts of projectiles on ceramic tiles and fracture tiles. Used in research on ceramics and ceramic-based composite materials such as armor. Hardness and low density of ceramics enable them to disintegrate projectiles more efficiently than metals. Projectile approaches ceramic tile specimen. Penetrating foil squares of triggering device activate display and recording instruments. As ceramic and resistive film break oscilloscope plots increase in electrical resistance of film.

  7. Method of sintering ceramic materials

    DOEpatents

    Holcombe, Cressie E.; Dykes, Norman L.

    1992-01-01

    A method for sintering ceramic materials is described. A ceramic article is coated with layers of protective coatings such as boron nitride, graphite foil, and niobium. The coated ceramic article is embedded in a container containing refractory metal oxide granules and placed within a microwave oven. The ceramic article is heated by microwave energy to a temperature sufficient to sinter the ceramic article to form a densified ceramic article having a density equal to or greater than 90% of theoretical density.

  8. Method of sintering ceramic materials

    DOEpatents

    Holcombe, C.E.; Dykes, N.L.

    1992-11-17

    A method for sintering ceramic materials is described. A ceramic article is coated with layers of protective coatings such as boron nitride, graphite foil, and niobium. The coated ceramic article is embedded in a container containing refractory metal oxide granules and placed within a microwave oven. The ceramic article is heated by microwave energy to a temperature sufficient to sinter the ceramic article to form a densified ceramic article having a density equal to or greater than 90% of theoretical density. 2 figs.

  9. Performance of a polarised neutron cryo-flipper using a high TcYBCO film

    NASA Astrophysics Data System (ADS)

    Parnell, S. R.; Washington, A. L.; Kaiser, H.; Li, F.; Wang, T.; Hamilton, W. A.; Baxter, D. V.; Pynn, R.

    2013-09-01

    It is well-known that the Meissner effect in superconducting materials can be used to provide a well-defined, non-adiabatic, magnetic-field transition. This can be utilised to produce a highly efficient neutron spin flipper that is suitable for use with neutrons of multiple wavelengths. Devices of this type using superconducting niobium have been deployed on neutron diffractometers for several decades but have required liquid helium to maintain the correct temperature. The use of high Tc materials, which removes the need for cryogens and simplifies the device, was first explored by Fitzsimmons et al. in [1]. In this communication, we describe a π flipper which uses commercially available films consisting of a 350-nm-thick YBCO film capped with 100 nm of gold on a 78×100×0.5 mm sapphire substrate. We discuss the design and performance of this device. The apparatus is compact (≈200 mm in length along the neutron beam), consisting of an oxygen-free high-conductivity copper frame, which holds the YBCO film and is mounted to the cold finger of a closed-cycle He refrigerator. The part of the vacuum chamber, where the YBCO film is located, is 5 cm wide, which allows us to minimise the distance from the film to the magnetic guide fields. Negligible small angle neutron scattering is observed from the flipper and its transmission is measured to be greater than 98.5% over a wide band of neutron wavelengths. In this design, the maximum neutron beam size that can be used is 42×42 mm2 and we can easily switch from a vertical to a horizontal guide field (both perpendicular to the neutron beam) on either side of the YBCO film. Data are reported for neutron wavelengths between 4 and 8.5 Å and flipping efficiencies under a variety of conditions are discussed. Under optimum conditions an efficiency of 99.5±0.3% was achieved for 4-8 Å neutrons on a pulsed source and 99.4±0.5% was achieved at a monochromatic source using a neutron wavelength of 4.2 Å.

  10. Homogenous Crack-Free Large Size YBCO/YSZ/Sapphire Films for Application

    NASA Astrophysics Data System (ADS)

    Almog, B.; Azoulay, M.; Deutscher, G.

    2006-09-01

    YBa2Cu3O7-δ (YBCO) films grown on Sapphire are highly suitable for applications. The production of large size (2-3″) homogeneous, thick (d ⩾ 600nm) films of high quality is of major importance. We report the growth of such films using a buffer layer of Yttrium-stabilized ZrO2(YSZ). The films are highly homogeneous and show excellent mechanical properties. They exhibit no sign of cracking even after many thermal cycles. Their critical thickness exceeds 1000nm. However, because of the large lattice mismatch there is a decrease in the electric properties(increases Rs, decreases jc).

  11. Corrosion of Ceramic Materials

    NASA Technical Reports Server (NTRS)

    Opila, Elizabeth J.; Jacobson, Nathan S.

    1999-01-01

    Non-oxide ceramics are promising materials for a range of high temperature applications. Selected current and future applications are listed. In all such applications, the ceramics are exposed to high temperature gases. Therefore it is critical to understand the response of these materials to their environment. The variables to be considered here include both the type of ceramic and the environment to which it is exposed. Non-oxide ceramics include borides, nitrides, and carbides. Most high temperature corrosion environments contain oxygen and hence the emphasis of this chapter will be on oxidation processes.

  12. Defect production in ceramics

    SciTech Connect

    Zinkle, S.J.; Kinoshita, C.

    1997-08-01

    A review is given of several important defect production and accumulation parameters for irradiated ceramics. Materials covered in this review include alumina, magnesia, spinel silicon carbide, silicon nitride, aluminum nitride and diamond. Whereas threshold displacement energies for many ceramics are known within a reasonable level of uncertainty (with notable exceptions being AIN and Si{sub 3}N{sub 4}), relatively little information exists on the equally important parameters of surviving defect fraction (defect production efficiency) and point defect migration energies for most ceramics. Very little fundamental displacement damage information is available for nitride ceramics. The role of subthreshold irradiation on defect migration and microstructural evolution is also briefly discussed.

  13. Thermoplastic Extrusion for Ceramic Bodies

    NASA Astrophysics Data System (ADS)

    Clemens, Frank

    Originally for the extrusion of ceramic bricks and tiles, clay and water were used to endow ceramic particle mixtures with sufficient plastic behaviour to permit practical shaping of the ceramic bodies. High-performance ceramics, however, often require the elimination of clay from extrusion formulations because the chemistry of the clay is incompatible with that of the desired ceramic materials. Therefore organic materials are frequently used in ceramic extrusion to provide plastic flow. Not only plastic behaviour is important for the extrusion of ceramic bodies. There are many other characteristics that can be tailored by the suitable addition of organics in a ceramic extrusion paste, or feedstock.

  14. Ceramic Technology Project

    SciTech Connect

    Not Available

    1992-03-01

    The Ceramic Technology Project was developed by the USDOE Office of Transportation Systems (OTS) in Conservation and Renewable Energy. This project, part of the OTS's Materials Development Program, was developed to meet the ceramic technology requirements of the OTS's automotive technology programs. Significant accomplishments in fabricating ceramic components for the USDOE and NASA advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. These programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and data base and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially. A five-year project plan was developed with extensive input from private industry. In July 1990 the original plan was updated through the estimated completion of development in 1993. The objective is to develop the industrial technology base required for reliable ceramics for application in advanced automotive heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. Although this is a generic materials project, the focus is on the structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barrier and wear applications in these engines. To facilitate the rapid transfer of this technology to US industry, the major portion of the work is being done in the ceramic industry, with technological support from government laboratories, other industrial laboratories, and universities.

  15. AFM nano-plough planar YBCO micro-bridges: critical currents and magnetic field effects.

    PubMed

    Elkaseh, A A O; Perold, W J; Srinivasu, V V

    2010-10-01

    The critical current (Ic) of YBa2Cu3O7-x (YBCO) AFM plough micro-constrictions is measured as a function of temperature, width and the magnetic flux density (B), which was applied perpendicular to the YBCO ab-plane and surface of the bridges. C-axis oriented thin films of YBa2Cu3O7-x were deposited on MgO substrates using an inverted cylindrical magnetron (ICM) sputtering technique. The films were then patterned into 8-10 micron size strips, using standard photolithography and dry etching processes. Micro-bridges with widths between 1.9 microm to 4.1 microm were fabricated by using atomic force microscope (AFM) nanolithography techniques. Critical current versus temperature data shows a straight-line behavior, which is typical of constriction type Josephson junctions. The Ic versus B characteristics exhibited a modulation, and a suppression of the critical current of up to 84%. It was also found that the critical current increases with increasing constriction width.

  16. YBCO microwave grain boundary mixer using a SrTiO[sub 3] bicrystal substrate

    SciTech Connect

    Seed, R.G.; Dorsey, P.C.; How, H.; Widom, A.; Vittoria, C. )

    1993-11-01

    A microwave mixer was patterned on a microstrip transmission line of superconducting YBCO (YBa[sub 2]Cu[sub 3]O[sub 7[minus]x]). The YBCO film was epitaxially laser deposited on a SrTiO[sub 3] bicrystal substrate. A weak link was constructed by patterning a microbridge In the microstrip at the bicrystal boundary. Two microwave signals were applied at the input of the microstrip line, one signal at 9.000 GM and the other signal at 9.941 GHz. An output intermediate frequency signal was observed at 941 MHz and was detected as the transmitted signal. The microbridge junction, which behaved as a resistively shunted Josephson junction (RSJ), was current biased slightly above the critical current I[sub c]. The mixer conversion loss was measured at the input and output ports of the device package. With these measurements, the mixing efficiency was determined at the device junction, and this measured efficiency was compared with the calculated efficiency. The calculated efficiency was determined by numerical solution of the Josephson equation for the weak link junction.

  17. Pinning properties of quenched and melt growth method-YBCO bulk samples

    NASA Astrophysics Data System (ADS)

    Okayasu, S.; Sasase, M.; Kuroda, N.; Iwase, A.; Kazumata, Y.; Kambara, T.

    2001-09-01

    A comparison between two different irradiation effects was accomplished on bulk YBCO samples synthesized with the quenched and melt growth method (QMG-YBCO) to investigate strong pinning properties. High-energy proton-irradiation introduces small defects comparable to unit cell size into the sample, and they act as effective pinning centers for all temperature range in low field around 1 T. No enhancement, however, can be seen in higher field range. The defects introduced with the irradiation reinforce the pinning properties of preexisting pinning centers randomly distributing in the sample. Column-like defects with 3.5 GeV Xe-irradiation were introduced but the pinning properties show no significant enhancement except higher temperature region. This indicates that pre-existing pinning centers are strong enough than the columnar defects. In higher field region, the contribution of columnar defects for pinning becomes relatively large. For both irradiation cases, almost pinning properties are determined by the pre-existing pinning centers.

  18. YBCO hot-electron bolometers dedicated to THz detection and imaging: Embedding issues

    NASA Astrophysics Data System (ADS)

    Aurino, M.; Kreisler, A. J.; Türer, I.; Martinez, A.; Gensbittel, A.; Dégardin, A. F.

    2010-06-01

    High-Tc hot-electron bolometers (HEB) are an interesting alternative to other superconducting heterodyne mixers in the terahertz frequency range because of low-cost cooling investment, ultra-wide instantaneous bandwidth and low intrinsic noise level, even at 80 K. A technological process to fabricate stacked yttrium-based (YBCO) / praseodymium-based (PBCO) ultra-thin films (in the 15 to 40 nm thickness range) etched to form 0.5 μm × 0.5 μm constrictions, elaborated on (100) MgO substrates, has been previously described. Ageing effects were also considered, with the consequence of increased electrical resistance, significant degradation of the regular THz response and no HEB mixing action. Electron and UV lithography steps are revisited here to realize HEB mixers based on nano-bridges covered by a log-periodic planar gold antenna, dedicated to the 1 to 7 THz range. Several measures have been attempted to reduce the conversion losses, mainly by considering the embedding issues related to the YBCO nano-bridge impedance matching to the antenna and the design of optimized intermediate frequency circuitry. Antenna simulations were performed and validated through experiments on scaled models at GHz frequencies. Electromagnetic coupling to the incoming radiation was also studied, including crosstalk between neighbour antennas forming a linear imaging array.

  19. Migrating from superconducting to semiconducting YBCO thin film bolometers as future far-infrared imaging pixels

    NASA Astrophysics Data System (ADS)

    Jagtap, Vishal S.; Longhin, Mattia; Kulsreshath, Mukesh K.; Kreisler, Alain J.; Dégardin, Annick F.

    2010-04-01

    YBa2Cu3O6+x compounds are well known to exhibit superconducting properties for x > 0.5 and semiconducting properties for lower oxygen content. Superconducting YBCO was obtained commercially; the semiconducting material was deposited by sputtering at room temperature. In order to migrate from superconducting to uncooled semiconducting far-infrared bolometer technologies, we have first realized and compared the performance of 2 × 2 pixel arrays made from both materials deposited on MgO substrates. Pixels were in the shape of meanders, embedded in an area of about 1 mm2. Pixel detectivity and thermal crosstalk were studied in the 1 Hz to 100 kHz modulation frequency range by using a 850 nm solid state laser. Secondly we have improved the geometry of semiconducting YBCO bolometers fabricated on silicon substrates, in order to match their impedance with the impedance of the antenna required for working in the THz range. First optical results are also presented, where both regular bolometric and pyroelectric responses are exhibited.

  20. An advanced low-fluorine solution route for fabrication of high-performance YBCO superconducting films

    NASA Astrophysics Data System (ADS)

    Chen, Yuanqing; Wu, Chuanbao; Zhao, Gaoyang; You, Caiyin

    2012-06-01

    We have developed a new low-fluorine solution consisting of non-fluorine (F-free) barium and copper salts, and fluorine-containing yttrium trifluoroacetate. Using this new low-fluorine solution, the BaCO3 phase was avoided in the pyrolyzed precursor films. Instead, CuO, Y and Ba fluorides (YF3 and BaF2) were formed in the precursor films pyrolyzed at 450 °C, which was the same as when an All-TFA solution (prepared using Y, Ba, Cu trifluoroacetates as precursors) or other fluorine-reduced solutions were used. This new kind of low-fluorine solution has only 23% of the fluorine content in an All-TFA solution, and the fluorine content was lower than any other fluorine-reduced solution. Thus, rapid production of YBa2Cu3O7-x (YBCO) films can be easily realized. Using a heating rate of 10 °C min-1 in the pyrolysis process, a high critical current density (Jc) of 5 MA cm-2 (at 77 K, 0 T) was obtained in YBCO films fabricated on LaAlO3 (LAO) single crystal substrates from the new starting solution.

  1. Microstructure dependence of the c-axis critical current density in second generation YBCO tapes

    SciTech Connect

    Jia, Y. Welp, U. Crabtree, G.W.; Kwok, W.K.; Malozemoff, A.P.; Rupich, M.W.; Fleshler, S.; Clem, J.R.

    2011-10-31

    C-axis current flow in high temperature superconductor (HTS) tape-shaped wires arises in configurations where the local wire axis is not perpendicular to the local magnetic field, such as in power cables with helically wound HTS tapes. The c-axis critical current density J{sub c}{sup c} has been recently found to be orders of magnitude lower than the ab-plane critical current density J{sub c}{sup ab}. Here we report on J{sub c}{sup c} (77 K, sf) values of various YBa{sub 2}Cu{sub 3}O{sub 7}-based (YBCO) tapes with different microstructures. Our results show that the value of J{sub c}{sup c} (77 K, sf) decreases significantly with increasing concentration of ab-plane stacking faults in YBCO thin films and that the critical current anisotropy {gamma} = J{sub c}{sup ab}/J{sub c}{sup c} can reach values as high as 2070, implying that in the highest-anisotropy tape, {approx}20% of the tape width carries c-axis current in a helically wound power cable.

  2. Microstructure dependence of the c-axis critical current density in second-generation YBCO tapes.

    SciTech Connect

    Jia, Y.; Welp, U.; Crabtree, G. W.; Kwok, W. K.; Malozemoff, A. P.; Rupich, M. W.; Fleshler, S.; Clem, J. R.

    2011-10-01

    C-axis current flow in high temperature superconductor (HTS) tape-shaped wires arises in configurations where the local wire axis is not perpendicular to the local magnetic field, such as in power cables with helically wound HTS tapes. The c-axis critical current density J{sub c}{sup c} has been recently found to be orders of magnitude lower than the ab-plane critical current density J{sub c}{sup ab}. Here we report on J{sub c}{sup c} (77 K, sf) values of various YBa{sub 2}Cu{sub 3}O{sub 7}-based (YBCO) tapes with different microstructures. Our results show that the value of J{sub c}{sup c} (77 K, sf) decreases significantly with increasing concentration of ab-plane stacking faults in YBCO thin films and that the critical current anisotropy {gamma} = J{sub c}{sup ab}/J{sub c}{sup c} can reach values as high as 2070, implying that in the highest-anisotropy tape, {approx}20% of the tape width carries c-axis current in a helically wound power cable.

  3. Inkjet printing of multifilamentary YBCO for low AC loss coated conductors

    NASA Astrophysics Data System (ADS)

    Hopkins, S. C.; Joseph, D.; Mitchell-Williams, T. B.; Calleja, A.; Vlad, V. R.; Vilardell, M.; Ricart, S.; Granados, X.; Puig, T.; Obradors, X.; Usoskin, A.; Falter, M.; Bäcker, M.; Glowacki, B. A.

    2014-05-01

    Considerable progress has been made with the development of REBCO coated conductors in recent years, and high performance conductors are available commercially. For many applications, however, the cost remains prohibitive, and AC losses discourage their selection for higher frequency applications. Chemical solution deposition (CSD) methods are attractive for low-cost, scalable preparation of buffer and superconductor layers, and in many respects inkjet printing is the method of choice, permitting non-contact deposition with minimal materials wastage and excellent control of coating thickness. Highly textured coatings of YBCO and Gd-doped CeO2 have previously been reported on buffered metal substrates. Inkjet printing also introduces the possibility of patterning - directly depositing two and three dimensional structures without subtractive processing - offering a low-cost route to coated conductors with reduced AC losses. In this contribution, the inkjet deposition of superconducting YBCO tracks is reported on industrially relevant buffered metal substrates both by direct printing and an inverse patterning approach. In the latter approach, ceria tracks were printed reported, which are a candidate both for resistive filament spacers and buffer layers. TFA-based precursor solutions have been printed on SS/ABAD-YSZ/CeO2 and Ni-W/LZO/CeO2 RABiTS substrates, and the resulting multifilamentary samples characterised by microscopy and scanning Hall probe measurements. The prospects for future inkjet-printed low AC loss coated conductors are discussed, including control of interfilamentary resistivity and bridging, transposed filamentary structures and stabilisation material.

  4. ARPES study of the YBCO phase diagram by in-situ K evaporation

    NASA Astrophysics Data System (ADS)

    Fournier, D.; Levy, G.; McCheyney, J. L.; Bostwick, A.; Rotenberg, E.; Hardy, W. N.; Liang, R. X.; Bonn, D. A.; Elfimov, I. S.; Damascelli, A.

    2010-03-01

    The study of the YBCO phase diagram by ARPES has become of central interest since the observation of quantum oscillations in high-magnetic field [1]. However, until recently accessing the various electronic phases by photoemission has been hampered by the so-called polar catastrophe [2]. In this work, the overdoped metal (OD, p=0.37, Tc=0), the superconducting phase (OP, TYBCO, we are able to identify the doping value at which the Luttinger description breaks down upon underdoping.[1] N. Doiron-Leyraud et al., Nature 447, 565 (2007).[2] M. A. Hossain et al., Nat. Phys. 4, 527 (2008).[3] K. M. Shen et al., Science 307, 901 (2005).

  5. VOLTAGE DISTRIBUTION AND MECHANICAL STRENGTH IN SPLICE JOINTS MADE FROM AS-MANUFACTURED YBCO COATED CONDUCTORS

    SciTech Connect

    Duckworth, Robert C; Zhang, Yifei; Gouge, Michael J; Rey, Christopher M; Van der Laan, Danko; Clickner, Cam

    2010-01-01

    With recommendations from wire manufacturers as a starting point, a series of solder joints were fabricated and characterized to determine the best method to produce repeatable, low-resistance and high-mechanical-strength splices in as-manufactured, stabilized YBCO coated conductors. From the 2.54 cm long splice joints that were fabricated, parameters such as solder material, stabilization material, fabrication method, and conductor geometry were varied to determine the impact of each on splice joint properties. Results indicate that the lowest resistance splice joints were influenced primarily by the tape orientation in the joint and the stabilization material. The lowest resistances were between 2 10-8 and 1.0 10-7 in 4-mm wide tapes and were obtained from pure copper stabilized tapes oriented with the YBCO layers in closest proximity. The voltage drop along the splice length indicated that only a fraction of the splice length contributes to the splice joint resistance. Mechanical characterization of splice joints showed that the joint resistance remained unchanged under axial stress up to a stress level at which the critical current of the tapes forming the joint degrades irreversibly.

  6. Method of making a modified ceramic-ceramic composite

    DOEpatents

    Weaver, Billy L.; McLaughlin, Jerry C.; Stinton, David P.

    1995-01-01

    The present invention provides a method of making a shaped ceramic-ceramic composite articles, such as gas-fired radiant heat burner tubes, heat exchangers, flame dispersers, and other furnace elements, having a formed-on ceramic-ceramic composite thereon.

  7. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2001-02-01

    This is the fifth quarterly report on a new study to develop a ceramic membrane/metal joint. Results of wetting experiments on commercially available Nickel based brazing alloys on perovskite surfaces are described. Additionally, experimental and numerical investigations on the strength of concentric ceramic/metal joints are presented.

  8. Industrial Ceramics: Secondary Schools.

    ERIC Educational Resources Information Center

    New York City Board of Education, Brooklyn, NY. Bureau of Curriculum Development.

    The expanding use of ceramic products in today's world can be seen in the areas of communications, construction, aerospace, textiles, metallurgy, atomic energy, and electronics. The demands of science have brought ceramics from an art to an industry using mass production and automated processes which requires the services of great numbers as the…

  9. Mounting for ceramic scroll

    DOEpatents

    Petty, Jack D.

    1993-01-01

    A mounting for a ceramic scroll on a metal engine block of a gas turbine engine includes a first ceramic ring and a pair of cross key connections between the first ceramic ring, the ceramic scroll, and the engine block. The cross key connections support the scroll on the engine block independent of relative radial thermal growth and for bodily movement toward an annular mounting shoulder on the engine. The scroll has an uninterrupted annular shoulder facing the mounting shoulder on the engine block. A second ceramic ring is captured between mounting shoulder and the uninterrupted shoulder on the scroll when the latter is bodily shifted toward the mouting shoulder to define a gas seal between the scroll and the engine block.

  10. Strain isolated ceramic coatings

    NASA Technical Reports Server (NTRS)

    Tolokan, R. P.; Brady, J. B.; Jarrabet, G. P.

    1985-01-01

    Plasma sprayed ceramic coatings are used in gas turbine engines to improve component temperature capability and cooling air efficiency. A compliant metal fiber strain isolator between a plasma sprayed ceramic coating and a metal substrate improves ceramic durability while allowing thicker coatings for better insulation. Development of strain isolated coatings has concentrated on design and fabrication of coatings and coating evaluation via thermal shock testing. In thermal shock testing, five types of failure are possible: buckling failure im compression on heat up, bimetal type failure, isothermal expansion mismatch failure, mudflat cracking during cool down, and long term fatigue. A primary failure mode for thermally cycled coatings is designated bimetal type failure. Bimetal failure is tensile failure in the ceramic near the ceramic-metal interface. One of the significant benefits of the strain isolator is an insulating layer protecting the metal substrate from heat deformation and thereby preventing bimetal type failure.

  11. Ceramic heat exchanger

    DOEpatents

    LaHaye, P.G.; Rahman, F.H.; Lebeau, T.P.; Severin, B.K.

    1998-06-16

    A tube containment system is disclosed. The tube containment system does not significantly reduce heat transfer through the tube wall. The contained tube is internally pressurized, and is formed from a ceramic material having high strength, high thermal conductivity, and good thermal shock resistance. The tube containment system includes at least one ceramic fiber braid material disposed about the internally pressurized tube. The material is disposed about the tube in a predetermined axial spacing arrangement. The ceramic fiber braid is present in an amount sufficient to contain the tube if the tube becomes fractured. The tube containment system can also include a plurality of ceramic ring-shaped structures, in contact with the outer surface of the tube, and positioned between the tube and the ceramic fiber braid material, and/or at least one transducer positioned within tube for reducing the internal volume and, therefore, the energy of any shrapnel resulting from a tube fracture. 6 figs.

  12. Ceramic heat exchanger

    DOEpatents

    LaHaye, Paul G.; Rahman, Faress H.; Lebeau, Thomas P. E.; Severin, Barbara K.

    1998-01-01

    A tube containment system. The tube containment system does not significantly reduce heat transfer through the tube wall. The contained tube is internally pressurized, and is formed from a ceramic material having high strength, high thermal conductivity, and good thermal shock resistance. The tube containment system includes at least one ceramic fiber braid material disposed about the internally pressurized tube. The material is disposed about the tube in a predetermined axial spacing arrangement. The ceramic fiber braid is present in an amount sufficient to contain the tube if the tube becomes fractured. The tube containment system can also include a plurality of ceramic ring-shaped structures, in contact with the outer surface of the tube, and positioned between the tube and the ceramic fiber braid material, and/or at least one transducer positioned within tube for reducing the internal volume and, therefore, the energy of any shrapnel resulting from a tube fracture.

  13. Enhancement of YBCO thin film thermal stability under 1 ATM oxygen pressure by intermediate Cu2O nanolayer.

    PubMed

    Cheng, L; Wang, X; Yao, X; Wan, W; Li, F H; Xiong, J; Tao, B W; Jirsa, M

    2010-06-10

    The melting process of YBa(2)Cu(3)O(x) (YBCO or Y123) films under an oxygen atmosphere was observed in situ by means of high-temperature optical microscopy. The films were classified by pole figure measurement as c-axis oriented, with two different in-plane orientations (denoted as 0 and 45 degrees). In the 45 degrees-oriented films, electron diffraction and high-resolution transmission electron microscopy (HRTEM) detected an intermediate Cu(2)O nanolayer in the vicinity of the interface. The melting mode and the thermal stability of the YBCO thin films with different in-plane orientations were greatly influenced by oxygen partial pressure. Notably, the thermal stability of the 45 degrees-oriented YBCO films dramatically grew with increasing oxygen partial pressure. We attributed this effect to a change in the intermediate Cu(2)O nanolayer thermal stability. We conclude and suggest that the thermal stability of YBCO films can be significantly enhanced by inserting a Cu(2)O buffer nanolayer.

  14. Influence of Both Cooling Rate and TeO2 Addition on the Properties of YBCO Superconductor

    NASA Astrophysics Data System (ADS)

    Ahmed, Yasser Momtaz Zaki; Hassan, Mervat Said; Abd-Elatif, Hassan

    2016-12-01

    Composite of superconducting system YBCO-TeO2 was synthesized utilizing solid-state reaction technique. Different weight percentages of TeO2 were mixed with a basic mixture [YBCO] for the synthesis of [YBa2Cu3O7- y ]1- x (TeO2) x composites. These mixtures were sintered at 1213 K (940 °C) for 24 hours and the samples cooled down by two different ways. The first way carried out via slowly cooling in furnace with the rate of 274 K/min to 275 K/min (1 °C/min to 2 °C/min) and the second one is quenching in oxygen gas. The XRD analysis showed that YBCO orthorhombic phase is the major phase appeared in all samples with different TeO2 content regardless of the cooling way. Additionally, minor unknown secondary phases appeared and enlarged with increasing TeO2 addition. Although quenched samples showed a phase difference between the sample's outer surface (orthorhombic) and its interior (tetragonal), the slowly cooled one did not clearly show such distinction. Moreover, doping YBCO with TeO2 leads to increase in the sample bulk density and reduction in their degradation degree in the wet atmosphere.

  15. In-Situ Deposition of YBCO/CeO2 on Biaxially Textured Ni Alloy Tapes by Thermal Coevaporation

    NASA Astrophysics Data System (ADS)

    Bindi, M.; Gianni, L.; Zannella, S.; Botarelli, A.; Baldini, A.; Gauzzi, A.; Tuissi, A.

    We report on the in-situ preparation and characterization of coated conductors consisting of a ~ 400 nm thick YBCO superconducting film grown by thermal co-evaporation on a ~ 200 nm thick CeO2 buffer layer grown by e-beam evaporation on biaxially textured Ni-Cr and Ni-V substrates. We studied the degree of texture of both YBCO and CeO2 layers as a function of substrate temperature during deposition and of oxygen partial pressure. X-ray diffraction patterns reveal that the highest degree of (100) texture of the buffer layer, necessary for the subsequent growth of the YBCO film with the desired c-axis orientation, is achieved at substrate temperatures of the order of 670-730°C. The backfilling of the chamber with oxygen during the cooling-down of the substrates after deposition of the CeO2 layer greatly improves the degree of crystallization of the buffer layer. YBCO films show good superconducting properties with critical temperatures Tc of the order of 87 K. Work is in progress to scale up the process for long tapes.

  16. Ceramic-silicide composites

    SciTech Connect

    Petrovic, J.J.

    1998-12-01

    The area of ceramic-silicide composites represents a merging of structural ceramics and structural silicides. Such ceramic-silicide composites can possess the desirable characteristics of both classes of compounds. Important structural ceramics are materials such as Si{sub 3}N{sub 4}, SiC, Al{sub 2}O{sub 3}, and ZrO{sub 2}, which possess covalent, ionic, or mixed covalent-ionic atomic bonding. An important structural silicide is MoSi{sub 2}, which possesses mixed covalent-metallic bonding. The arena of ceramic-silicide composites encompasses both composites where the structural silicide is the matrix and the structural ceramic is the reinforcement, and composites where the structural ceramic is the matrix and the structural silicide is the reinforcement. In the former area, MoSi{sub 2}-SiC, MoSi{sub 2}-ZrO{sub 2}, and MoSi{sub 2}-Al{sub 2}O{sub 3} composites are discussed. In the latter area, Si{sub 3}N{sub 4}-MoSi{sub 2} composites are described.

  17. High pressure ceramic joint

    DOEpatents

    Ward, Michael E.; Harkins, Bruce D.

    1993-01-01

    Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present joint when used with recuperators increases the use of ceramic components which do not react to highly corrosive gases. Thus, the present joint used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present joint is comprised of a first ceramic member, a second ceramic member, a mechanical locking device having a groove defined in one of the first ceramic member and the second ceramic member. The joint and the mechanical locking device is further comprised of a refractory material disposed in the groove and contacting the first ceramic member and the second ceramic member. The present joint mechanically provides a high strength load bearing joint having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures.

  18. High pressure ceramic joint

    DOEpatents

    Ward, M.E.; Harkins, B.D.

    1993-11-30

    Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present joint when used with recuperators increases the use of ceramic components which do not react to highly corrosive gases. Thus, the present joint used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present joint is comprised of a first ceramic member, a second ceramic member, a mechanical locking device having a groove defined in one of the first ceramic member and the second ceramic member. The joint and the mechanical locking device is further comprised of a refractory material disposed in the groove and contacting the first ceramic member and the second ceramic member. The present joint mechanically provides a high strength load bearing joint having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures. 4 figures.

  19. The APS ceramic chambers

    SciTech Connect

    Milton, S.; Warner, D.

    1994-07-01

    Ceramics chambers are used in the Advanced Photon Source (APS) machines at the locations of the pulsed kicker and bumper magnets. The ceramic will be coated internally with a resistive paste. The resistance is chosen to allow the low frequency pulsed magnet field to penetrate but not the high frequency components of the circulating beam. Another design goal was to keep the power density experienced by the resistive coating to a minimum. These ceramics, their associated hardware, the coating process, and our recent experiences with them are described.

  20. Spacecraft ceramic protective shield

    NASA Technical Reports Server (NTRS)

    Larriva, Rene F. (Inventor); Nelson, Anne (M.); Czechanski, James G. (Inventor); Poff, Ray E. (Inventor)

    1995-01-01

    A low areal density protective shield apparatus, and method for making same, for protecting spacecraft structures from impact with hypervelocity objects, including a bumper member comprising a bumper ceramic layer, a bumper shock attenuator layer, and a bumper confining layer. The bumper ceramic layer can be SiC or B.sub.4 C; the bumper shock attenuator layer can be zirconia felt; and the bumper confining layer can be aluminum. A base armor member can be spaced from the bumper member and a ceramic fiber-based curtain can be positioned between the bumper and base armor members.

  1. Ceramic Stationary Gas Turbine Development. Technical progress report, April 1, 1993--October 31, 1994

    SciTech Connect

    1994-12-01

    This report summarizes work performed by Solar Technologies Inc. and its subcontractors, during the period April 1, 1993 through October 31, 1994 under Phase II of the DOE Ceramic Stationary Gas Turbine Development program. The objective of the program is to improve the performance of stationary gas turbines in cogeneration through the implementation of selected ceramic components.

  2. In-plane orientation effect on the melting behaviour of YBCO thin film.

    PubMed

    Tang, Chen Y; Cai, Yan Q; Yao, Xin; Rao, Qun L; Tao, Bo W; Li, Yan R

    2007-02-21

    By means of high-temperature optical microscopy (HTOM), a 60 °C gap in initial melting temperature between two YBa₂Cu₃O(x) (Y123) thin films was found in situ. Using these two films as seeds, liquid phase epitaxy (LPE) dipping experiments showed the same tendency in the melting behaviour. The in-plane orientation was detected by x-ray diffraction (XRD) pole figure. On the basis of results from HTOM, LPE and XRD, it was unveiled that the interface structure has a predominant influence on the melting mode. A semi-coherent interface suppresses not only the melting growth but also the melting nucleation, while an incoherent interface encourages both of them. (In this work, melting of YBCO refers to the peritectic decomposition of Y123.).

  3. (abstract) All Epitaxial Edge-geometry SNS Devices with Doped PBCO and YBCO Normal Layers

    NASA Technical Reports Server (NTRS)

    Barner, J. B.; Hunt, B. D.; Foote, M. C.

    1995-01-01

    We will present our results on tapered-edge-geometry SNS weak link fabricated from c-axis oriented base-, counterelectrode and normal layers using a variety of processing conditions. To date, we have employed a variety of different normal materials (Co-doped YBCO, Y-doped PBCO, Ca-doped PBCO). We have been examining the junction fabrication process in detail and we will present our methods. In particular, we have been examining both epitaxial and non-epitaxial milling mask overlayers and we will present a comparison of both methods. These devices behave similar to the expectations of the resisively shunted junction model and conventional SNS proximity effect models but with some differences which will be discussed. We will present the detailed systematics of our junctions including device parameters versus temperature, rf and dc magnetic response for the various processing conditions.

  4. 2D SQIF arrays using 20 000 YBCO high R n Josephson junctions

    NASA Astrophysics Data System (ADS)

    Mitchell, E. E.; Hannam, K. E.; Lazar, J.; Leslie, K. E.; Lewis, C. J.; Grancea, A.; Keenan, S. T.; Lam, S. K. H.; Foley, C. P.

    2016-06-01

    Superconducting quantum interference filters (SQIFs) have been created using two dimensional arrays of YBCO step-edge Josephson junctions connected together in series and parallel configurations via superconducting loops with a range of loop areas and loop inductances. A SQIF response, as evidenced by a single large anti-peak at zero applied flux, is reported at 77 K for step-edge junction arrays with the junction number N = 1 000 up to 20 000. The SQIF sensitivity (slope of peak) increased linearly with N up to a maximum of 1530 V T-1. Array parameters related to geometry and average junction characteristics are investigated in order to understand and improve the SQIF performance in high temperature superconducting arrays. Initial investigations also focus on the effect of the SQUID inductance factor on the SQIF sensitivity by varying both the mean critical current and the mean inductance of the loops in the array. The RF response to a 30 MHz signal is demonstrated.

  5. Microstructure development in repeated zone refining of microwave-derived YBCO bulk compacts

    NASA Astrophysics Data System (ADS)

    Varma, Hari K.; Warrier, Krishna G.; Kumar, Viswanathan A.; Mani, Themanam V.; Pillai, Sankara P. G. K.; Damodaran, Alathur D.

    1992-05-01

    YBCO precursor particulates have been prepared using microwave decomposition of a mixture of yttrium, barium and copper nitrates in a microwave oven having the frequency 2.45 GHz and 600 W power, within as short as 240 seconds. This precursor, upon further compaction into strips of 10 mm x 60 mm x 1 mm and sintering at 940 C for 5 h, attained 90 percent density. Such strips are subjected to repeated zone refining operations in a zone refining system having a three-zone furnace at relatively high speeds of 30 mm/h. The development of microstructure in such samples from the as-sintered condition through the various steps has been presented. A microstructure having uniformly oriented grains in the a-b plane throughout the bulk of the sample could be obtained by three repeated zone refining operations. The possibility of introducing a faster movement of the melting zone compared to earlier reports is highlighted.

  6. Factors that influence particle formation during pulsed electron deposition of YBCO precursors

    NASA Astrophysics Data System (ADS)

    Mathis, John E.; Christen, Hans M.

    2007-08-01

    Pulsed electron deposition (PED) is an attractive alternative to pulsed laser deposition (PLD) for growing thin films because of PED’s relatively low cost. A potential problem with PED, however, is the generation of particulates that interfere with film growth. The influence of ambient pressure and accelerating potential on the number of and size of particulates appearing on the surface of films was investigated for the barium fluoride-based YBCO precursor process. It was found that the size of the particulates varies exponentially with accelerating voltage. The size of the particulates can be reduced to less than 100 nm by increasing the ambient pressure beyond that required for optimum deposition rate. The ability to control the size of particulates could make PED useful for technical applications where the generation of sub-micron sized materials is desired.

  7. Powder metallurgy for the fabrication of bi-axially textured Ni tapes for YBCO coated conductors

    NASA Astrophysics Data System (ADS)

    Lee, Dong-Wook; Ki Ji, Bong; Hyung Lim, Jun; Jung, Choong-Hwan; Joo, Jinho; Park, Soon-Dong; Jun, Byung-Hyuk; Hong, Gye-Won; Kim, Chan-Joong

    2003-04-01

    Bi-axially textured Ni tapes for YBCO coated conductors were fabricated by forming, sintering, cold rolling and heat treatment of Ni powder compacts. The powder metallurgy process consists of filling of fine Ni powders in a rubber mold, cold isostatical pressing in a water chamber and sintering of the powder compacts. The sintered compacts were cold-rolled and made into tapes with a thickness of 100 micron and then heat-treated at 1000 °C for various time periods for the development of the (2 0 0) texture. The (2 0 0) texture of Ni tape was successfully formed through the optimization of the recrystallization heat treatment condition for the cold rolled Ni tapes. The full width half maximum of the Ni tapes was 8-10° and the atomic force microscopy surface roughness was 3-5 nm.

  8. Surface Resistance of YBCO Thin Films under High DC Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Ohshima, S.; Kitamura, K.; Noguchi, Y.; Sekiya, N.; Saito, A.; Hirano, S.; Okai, D.

    2006-06-01

    We have studied the magnetic dependence of the surface resistance (Rs) of YBa2Cu3Oy (YBCO) thin films by changing the direction of an applied magnetic field by mean of a micriostrip line resonator method (MLRM). We measured Rs(0), Rs(90) and Rs(45) to which the direction of the applied magnetic field was respectively normal, parallel and at 45° to the film surface. In the low temperature region, (below 40 K), the Rs(0) had low magnetic dependence; however, the Rs(90) and Rs(45) had high magnetic dependence, even below 10 K. We examined the magnetic field dependence of Rs (90) and Rs(0) using the London equation, and found that Rs(90) in the higher temperature region could be mostly explained by the theory.

  9. Nanowall pinning for enhanced pinning force in YBCO films with nanofabricated structures

    NASA Astrophysics Data System (ADS)

    Palau, A.; Rouco, V.; Luccas, R. F.; Obradors, X.; Puig, T.

    2014-11-01

    High resolution nanofabrication tools (Focused Ion Beam and Electron Beam Lithography) have been used to fabricate nano-metric milled structures in high critical current YBCO thin films able to further increase their vortex pinning capabilities. We have demonstrated that pinning forces at 77 K and 3 T are increased by a 70-80% by proper nanostructure designs. Model systems with linear trenches and triangular blind antidots of different sizes, distribution and density have been generated and studied. We demonstrate that specific milled nanostructures can increase the total current through the system at expenses of a limited decrease of cross section. We have identified the length of fabricated nano-walls as the main parameter controlling the pinning potential of nanostructures and thus defined the optimised milling conditions and nanostructure morphology to maximise pinning efficiency.

  10. Grain boundary degradation of YBCO superconductors sintered in CO{sub 2}-containing atmospheres

    SciTech Connect

    Balachandran, U.; Merkle, K.L.; Mundy, J.N.; Gao, Y.; Zhang, C.; Xu, D.; Selvaduray, G.

    1993-11-01

    The transport critical current density (J{sub c}) of YBCO superconductors decreased with increasing CO{sub 2} partial pressure in the sintering atmosphere and ultimately reached zero, even though magnetization measurements showed that the bulk of the samples with zero J{sub c} remained superconducting. The microstructure and composition of the samples was investigated by high resolution transmission electron microscopy and secondary-ion mass spectroscopy (SIMS). Microbeam SIMS indicated carbon segregation at grain boundaries (GBs). Approximately 10% of the GBs were coated with a thin layer of a second phase, deduced to be BaCuO{sub 2} and BaCu{sub 2}O{sub 2}. Near some grain boundaries, the structure was tetragonal within several tens of nm of the boundaries. The degradation of J{sub c} is discussed in terms of the partial pressure of CO{sub 2} and the processing temperatures. Detailed examination of GB microstructures is given in this paper.

  11. Scanning hall probe microscopy of AC losses in YBCO coated conductors

    NASA Astrophysics Data System (ADS)

    Dinner, Rafael; Daniels, George; Larbalestier, David; Gibbons, Brady; Matias, Vladimir; Moler, Kathryn; Beasley, Malcolm

    2005-03-01

    Magnetic imaging of current-induced vortex movement in superconducting films yields detailed information about dissipation and the path of an applied current. In our large-area scanning hall probe microscope, a flow cryostat cools a sample while a micro-Hall probe is rastered near its surface using a 3-axis stepper-motor-based stage with submicron resolution and centimeter scan range. Hall probe time traces taken at each point are assembled into movies of the flux penetration as a function of time over a cycle of AC sample current. YBCO films grown on several substrates are examined, including bicrystal substrates that induce a single grain boundary across the current path and metal tapes that give rise to a grain boundary network. An extended Bean model allows us to extract pinning forces and critical currents of the intragrain film and its grain boundaries.

  12. Comparison of CSD-YBCO growth on different single crystal substrates

    NASA Astrophysics Data System (ADS)

    Kunert, J.; Bäcker, M.; Falter, M.; Schroeder-Obst, D.

    2008-02-01

    2G HTS Coated Conductors properties can be improved by comparing different raw materials, precursor production routes and coating and annealing conditions. To suppress the influence of varying substrate tapes and buffer layer qualities on the HTS layers, a standard substrate is needed to improve the Jc values. In this work various pure single crystal substrates (SrTiO3 [STO], (LaAlO3)0.3(Sr2AlTaO6)0.7 [LSAT], LaAlO3 [LAO], NdGaO3 [NdGaO]) are investigated to find the material which is best in terms of price, texture and morphological layout and instantaneous availability. YBCO films deposited onto these substrates via chemical solution deposition (CSD) are analysed using XRD texture analysis, surface morphology analysis (high resolution AFM) and inductive measurement of the critical current density.

  13. Preparation of high grade YBCO powders and pellets through the glycerol route

    NASA Astrophysics Data System (ADS)

    Kamat, R. V.; Vittal Rao, T. V.; Pillai, K. T.; Vaidya, V. N.; Sood, D. D.

    1991-10-01

    Superconducting powders and pellets of Y-Ba-Cu-O were prepared by a new solution route. Nitrates of Y, Ba and Cu were heated with a controlled amount of glycerol to get a dry powder which on suitable heat treatment gave high grade YBCO powder/pellets. Characterisation was done by X-ray diffractometry, thermogravimetry, differential thermal analysis and also by measuring the surface area, carbon-content, bulk-density, transition temperature and the critical current. The pellets could be densified to 94% theoretical density (TD) and had a superconducting transition width of 1 K. The critical current densities were in the range of 200-500 A/cm 2.

  14. Fabrication of a good-quality single grain YBCO sample through the control of seed crystals

    SciTech Connect

    Kim, C.J.; Hong, G.W.; Jee, Y.A.; Han, Y.H.; Han, S.C.; Sung, T.H.

    1999-09-01

    The authors investigated the growth mode of YBa{sub 2}Cu{sub 3}O{sub 7{minus}y} (Y123) grains and its effect on the levitation forces and trapped magnetic field of top-seeded melt processed YBCO samples. When a slab-like Sm-seed was used, undesirable subsidiary Y123 grains were formed, while the formation of the subsidiary Y123 grains was suppressed and a nearly single Y123 grain grew when a thick and wide seed was used. The formation of the subsidiary Y123 grains decreased the levitation forces and trapped magnetic field, due to the presence of grain boundaries with weak link characteristics.

  15. Observation of step structures in the I-V characteristics of YBCO thin films

    NASA Astrophysics Data System (ADS)

    Azoulay, J.; Verdyan, A.; Lapsker, I.

    1997-08-01

    Many electrical properties of the high Tc superconductors are widely probed utilizing current-voltage characteristics because of its sensitivity to the phase transition. In this work we report on detailed study of YBCO I-V characteristics shape above the critical current in the phase transition vicinity. For a given temperature controlled to a better than 10mK stability over the whole I-V cycle, the applied current has been gradually increased to exceed the critical current. The system has thus been driven to cross over to the mixed state. Using dI/dV versus V plots, it is shown that all the curves are characterized by a fine step structures at current densities higher than the critical ones.

  16. Calibration of Hall sensor array for critical current measurement of YBCO tape with ferromagnetic substrate

    NASA Astrophysics Data System (ADS)

    Zhu, Yunpeng; Wang, Gang; Liu, Liyuan; Yang, Xinsheng; Zhao, Yong

    2015-12-01

    HAS (Hall sensor array) is a powerful tool to detect the uniformity of HTS (high temperature superconductor) tape through mapping the distribution of remanent or shielding field along the surface of the tape. However, measurement of HTS tape with ferromagnetic parts by HSA is still an issue because the ferromagnetic substrate has influence on the magnetic field around the HTS layer. In this work, a continuous HSA system has been designed to measure the critical current of the YBCO tape with ferromagnetic substrate. The relationship between the remanent field and critical current was calibrated by the finite element method. The result showed that the HSA is an effective method for evaluating the critical current of the HTS tape with ferromagnetic substrate.

  17. Magnetic levitation and its application for education devices based on YBCO bulk superconductors

    NASA Astrophysics Data System (ADS)

    Yang, W. M.; Chao, X. X.; Guo, F. X.; Li, J. W.; Chen, S. L.

    2013-10-01

    A small superconducting maglev propeller system, a small spacecraft model suspending and moving around a terrestrial globe, several small maglev vehicle models and a magnetic circuit converter have been designed and constructed. The track was paved by NdFeB magnets, the arrangement of the magnets made us easy to get a uniform distribution of magnetic field along the length direction of the track and a high magnetic field gradient in the lateral direction. When the YBCO bulks mounted inside the vehicle models or spacecraft model was field cooled to LN2 temperature at a certain distance away from the track, they could be automatically floating over and moving along the track without any obvious friction. The models can be used as experimental or demonstration devices for the magnetic levitation applications.

  18. Detectors of Infrared Radiation Based on High T(c) Superconducting YBCO Films

    DTIC Science & Technology

    1991-06-01

    d4 . mvuAT.OATS 3. AIPOST ’l ’ TE ’OEE FINAL REPORT 1 Dec 87-30 Apr 90 Detectors of Infrared Radiation Based on High T(c) Superconducting YBCO Films...YBa2CU3O7 film on LaAlO3 at 6.8 K biased with 20.6 mA. > .11 --- . I’ M e nsq FW m.. E\\pe of th .5.i.=nl 3(0wnN n UA*. ). l=btototpte vCV ra. dt mdm lenmo ,5,25 ind 9W nj/pu- 4=5mAT=8s’

  19. Corrosion resistant ceramic materials

    DOEpatents

    Kaun, T.D.

    1996-07-23

    Ceramic materials are disclosed which exhibit stability in severely-corrosive environments having high alkali-metal activity, high sulfur/sulfide activity and/or molten halides at temperatures of 200--550 C or organic salt (including SO{sub 2} and SO{sub 2}Cl{sub 2}) at temperatures of 25--200 C. These sulfide ceramics form stoichiometric (single-phase) compounds with sulfides of Ca, Li, Na, K, Al, Mg, Si, Y, La, Ce, Ga, Ba, Zr and Sr and show melting-points that are sufficiently low and have excellent wettability with many metals (Fe, Ni, Mo) to easily form metal/ceramic seals. Ceramic compositions are also formulated to adequately match thermal expansion coefficient of adjacent metal components. 1 fig.

  20. Corrosion resistant ceramic materials

    DOEpatents

    Kaun, Thomas D.

    1996-01-01

    Ceramic materials which exhibit stability in severely-corrosive environments having high alkali-metal activity, high sulfur/sulfide activity and/or molten halides at temperatures of 200.degree.-550.degree. C. or organic salt (including SO.sub.2 and SO.sub.2 Cl.sub.2) at temperatures of 25.degree.-200.degree. C. These sulfide ceramics form stoichiometric (single-phase) compounds with sulfides of Ca, Li, Na, K, Al, Mg, Si, Y, La, Ce, Ga, Ba, Zr and Sr and show melting-points that are sufficiently low and have excellent wettability with many metals (Fe, Ni, Mo) to easily form metal/ceramic seals. Ceramic compositions are also formulated to adequately match thermal expansion coefficient of adjacent metal components.

  1. Corrosion resistant ceramic materials

    DOEpatents

    Kaun, Thomas D.

    1995-01-01

    Ceramic materials which exhibit stability in severely-corrosive environments having high alkali-metal activity, high sulfur/sulfide activity and/or molten halides at temperatures of 200.degree.-550.degree. C. or organic salt (including SO.sub.2 and SO.sub.2 Cl.sub.2) at temperatures of 25.degree.-200.degree. C. These sulfide ceramics form stoichiometric (single-phase) compounds with sulfides of Ca, Li, Na, K, Al, Mg, Si, Y, La, Ce, Ga, Ba, Zr and Sr and show melting-points that are sufficiently low and have excellent wettability with many metals (Fe, Ni, Mo) to easily form metal/ceramic seals. Ceramic compositions are also formulated to adequately match thermal expansion coefficient of adjacent metal components.

  2. Fibrous ceramic insulation

    SciTech Connect

    Goldstein, H.E.

    1982-11-01

    Some of the reusable heat shielding materials used to protect the Space Shuttles, their manufacturing processes, properties, and applications are discussed. Emphasis is upon ceramic materials. Space Shuttle Orbiter tiles are discussed.

  3. Light emitting ceramic device

    DOEpatents

    Valentine, Paul; Edwards, Doreen D.; Walker, Jr., William John; Slack, Lyle H.; Brown, Wayne Douglas; Osborne, Cathy; Norton, Michael; Begley, Richard

    2010-05-18

    A light-emitting ceramic based panel, hereafter termed "electroceramescent" panel, is herein claimed. The electroceramescent panel is formed on a substrate providing mechanical support as well as serving as the base electrode for the device. One or more semiconductive ceramic layers directly overlay the substrate, and electrical conductivity and ionic diffusion are controlled. Light emitting regions overlay the semiconductive ceramic layers, and said regions consist sequentially of a layer of a ceramic insulation layer and an electroluminescent layer, comprised of doped phosphors or the equivalent. One or more conductive top electrode layers having optically transmissive areas overlay the light emitting regions, and a multi-layered top barrier cover comprising one or more optically transmissive non-combustible insulation layers overlay said top electrode regions.

  4. Making Ceramic Cameras

    ERIC Educational Resources Information Center

    Squibb, Matt

    2009-01-01

    This article describes how to make a clay camera. This idea of creating functional cameras from clay allows students to experience ceramics, photography, and painting all in one unit. (Contains 1 resource and 3 online resources.)

  5. Advanced Ceramics Property Measurements

    NASA Technical Reports Server (NTRS)

    Salem, Jonathan; Helfinstine, John; Quinn, George; Gonczy, Stephen

    2013-01-01

    Mechanical and physical properties of ceramic bodies can be difficult to measure correctly unless the proper techniques are used. The Advanced Ceramics Committee of ASTM, C-28, has developed dozens of consensus test standards and practices to measure various properties of a ceramic monolith, composite, or coating. The standards give the "what, how, how not, and why" for measurement of many mechanical, physical, thermal, and performance properties. Using these standards will provide accurate, reliable, and complete data for rigorous comparisons with other test results from your test lab, or another. The C-28 Committee has involved academics, producers, and users of ceramics to write and continually update more than 45 standards since the committee's inception in 1986. Included in this poster is a pictogram of the C-28 standards and information on how to obtain individual copies with full details or the complete collection of standards in one volume.

  6. Ceramic fiber filter technology

    SciTech Connect

    Holmes, B.L.; Janney, M.A.

    1996-06-01

    Fibrous filters have been used for centuries to protect individuals from dust, disease, smoke, and other gases or particulates. In the 1970s and 1980s ceramic filters were developed for filtration of hot exhaust gases from diesel engines. Tubular, or candle, filters have been made to remove particles from gases in pressurized fluidized-bed combustion and gasification-combined-cycle power plants. Very efficient filtration is necessary in power plants to protect the turbine blades. The limited lifespan of ceramic candle filters has been a major obstacle in their development. The present work is focused on forming fibrous ceramic filters using a papermaking technique. These filters are highly porous and therefore very lightweight. The papermaking process consists of filtering a slurry of ceramic fibers through a steel screen to form paper. Papermaking and the selection of materials will be discussed, as well as preliminary results describing the geometry of papers and relative strengths.

  7. Super Thin Ceramic Coatings

    NASA Video Gallery

    New technology being developed at NASA's Glenn Research Center creates super thin ceramic coatings on engine components. The Plasma Spray – Physical Vapor Deposition (PS-PVD) rig uses a powerful ...

  8. Increasing the sensitivity of the spectrophotometric determinations of the oxygen content in YBCO superconducting samples using the I(3-)-starch compound.

    PubMed

    Nedeltcheva, Tsvetanka K; Georgieva, Stela Iv; Vladimirova, Latinka K; Stoyanova-Ivanova, Angelina K

    2009-03-15

    The conditions for formation of the I(3)(-)-starch compound and measuring its absorbance have been found, and a spectrophotometric method has been developed for the determination of the oxygen content in YBa(2)Cu(3)O(y) superconducting bulk samples. The method involves the following stages: a decomposition of the sample in an acid medium in the presence of iodide ions under inert atmosphere; formation of a complex between Cu(II) and glycine; binding the I(3)(-)-complex with a starch and the absorbance measurement of the colored I(3)(-)-starch compound. The coefficient of the active oxygen is calculated by the ratio of the absorbances of two solutions and the method does not require both calibration and precise measuring sample mass. The accuracy of the results is confirmed applying the comparative spectrophotometric method that uses the yellow I(3)(-)-complex. The precision of the results evaluated by the relative standard deviation is 2%. The developed method is sensitive and allows a sample mass about 2mg to be used. The analysis is rapid and requires a simple and inexpensive apparatus. Thus the new method would be useful for an express analytical control of the oxygen content of YBCO-superconducting materials produced for the electronics.

  9. Letter report on PCT/Monolith glass ceramic corrosion tests

    SciTech Connect

    Crawford, Charles L.

    2015-09-24

    The Savannah River National Laboratory (SRNL) is collaborating with personnel from Pacific Northwest National Laboratory (PNNL) to study advanced waste form glass ceramics for immobilization of waste from Used Nuclear Fuel (UNF) separations processes. The glass ceramic waste forms take advantage of both crystalline and glassy phases where ‘troublesome’ elements (e.g., low solubility in glass or very long-lived) partition to highly durable ceramic phases with the remainder of elements residing in the glassy phase. The ceramic phases are tailored to create certain minerals or unique crystalline structures that can host the radionuclides by binding them in their specific crystalline network while not adversely impacting the residual glass network (Crum et al., 2011). Glass ceramics have been demonstrated using a scaled melter test performed in a pilot scale (1/4 scale) cold crucible induction melter (CCIM) (Crum et al., 2014; Maio et al., 2015). This report summarizes recent results from both Phase I and Phase II bench scale tests involving crucible fabrication and corrosion testing of glass ceramics using the Product Consistency Test (PCT). Preliminary results from both Phase I and Phase II bench scale tests involving statistically designed matrices have previously been reported (Crawford, 2013; Crawford, 2014).

  10. Fabrication of interface-modified ramp-edge junction on YBCO ground plane with multilayer structure

    NASA Astrophysics Data System (ADS)

    Wakana, H.; Adachi, S.; Kamitani, A.; Sugiyama, H.; Sugano, T.; Horibe, M.; Ishimaru, Y.; Tarutani, Y.; Tanabe, K.

    2003-10-01

    We examined the fabrication conditions to obtain high-quality ramp-edge Josephson junctions on a liquid-phase-epitaxy YBa 2Cu 3O y (LPE-YBCO) ground plane, in particular, focusing on the fabrication of a suitable insulating layer on the ground plane and the post-annealing conditions to load oxygen to the ground plane. A (LaAlO 3) 0.3-(SrAl 0.5Ta 0.5O 3) 0.7 (LSAT) insulating film on the ground planes exhibited a conductance ranging from 10 -4 to 10 -8 S after deposition of an upper superconducting film, suggesting existence of some leak paths through the LSAT insulating layer. By introducing approximately 30 nm thick SrTiO 3 (STO) buffer layers on both side of the LSAT insulating layer. We reproducibly obtained a conductance lower than 10 -8 S. The dielectric constant of the STO/LSAT/STO layer was 32, which was slightly larger than that of the single LSAT layer. It was found that a very slow cooling rate of 1.0 °C/h in oxygen was needed to fully oxidize the ground plane through the STO/LSAT/STO insulating layers, while the oxidation time could be effectively reduced by introducing via holes in the insulating layer at an interval of 200 μm. Ramp-edge junctions on LPE-YBCO ground planes with STO/LSAT/STO insulating layers exhibited a 1 σ-spread in Ic of 8% for 100-junction series-arrays and a sheet inductance of 0.7 pH/□ at 4.2 K.

  11. STANFORD IN-SITU HIGH RATE YBCO PROCESS: TRANSFER TO METAL TAPES AND PROCESS SCALE UP

    SciTech Connect

    Malcolm R. Beasley; Robert H.Hammond

    2009-04-14

    Executive Summary The materials science understanding of high rate low cost processes for Coated Conductor will benefit the application to power utilities for low loss energy transportation and power generation as well for DOD applications. The research in this program investigated several materials processing approaches that are new and original, and are not being investigated elsewhere. This work added to the understanding of the material science of high rate PVD growth of HTSC YBCO assisted by a liquid phase. A new process discovered uses amorphous glassy precursors which can be made at high rate under flexible conditions of temperature and oxygen, and later brought to conditions of oxygen partial pressure and temperature for rapid conversion to YBCO superconductor. Good critical current densities were found, but further effort is needed to optimize the vortex pinning using known artificial inclusions. A new discovery of the physics and materials science of vortex pinning in the HTSC system using Sm in place of Y came at growth at unusually low oxygen pressure resulting in clusters of a low or non superconducting phase within the nominal high temperature phase. The driving force for this during growth is new physics, perhaps due to the low oxygen. This has the potential for high current in large magnetic fields at low cost, applicable to motors, generators and transformers. The technical demands of this project were the motivation for the development of instrumentation that could be essential to eventual process scale up. These include atomic absorption based on tunable diode lasers for remote monitoring and control of evaporation sources (developed under DARPA support), and the utility of Fourier Transform Infrared Reflectivity (FTIR) for aid in the synthesis of complex thin film materials (purchased by a DURIP-AFOSR grant).

  12. Numerical simulation and analysis of single grain YBCO processed from graded precursor powders

    NASA Astrophysics Data System (ADS)

    Zou, J.; Ainslie, M. D.; Hu, D.; Zhai, W.; Devendra Kumar, N.; Durrell, J. H.; Shi, Y.-H.; Cardwell, D. A.

    2015-03-01

    Large single-grain bulk high-temperature superconducting materials can trap high magnetic fields in comparison with conventional permanent magnets, making them ideal candidates to develop more compact and efficient devices, such as actuators, magnetic levitation systems, flywheel energy storage systems and electric machines. However, macro-segregation of Y-211 inclusions in melt processed Y-Ba-Cu-O (YBCO) limits the macroscopic critical current density Jc of such bulk superconductors, and hence, the potential trapped field. Recently, a new fabrication technique with graded precursor powders has been developed, which results in a more uniform distribution of Y-211 particles, in order to further improve the superconducting properties of such materials. In order to develop this graded fabrication technique further, a 3D finite-element numerical simulation based on the H-formulation is performed in this paper. The trapped field characteristics of a graded YBCO sample magnetized by the field cooling method are simulated to validate the model, and the simulation results are consistent with the experimental measurements. In addition, the influence of the graded technique and various graded Jc distributions for pulsed field magnetization, recognized widely as a practical route for magnetizing samples in bulk superconductor applications, is also investigated, with respect to the trapped field and temperature profiles of graded samples. This modelling framework provides a new technique for assessing the performance of various sizes and geometries of graded bulk superconductors, and by adjusting the Y-211, and hence Jc, distribution, samples can be fabricated based on this concept to provide application-specific trapped field profiles, such as the generation of either a high magnetic field gradient or a high level of uniformity for the traditionally conical, trapped field profile.

  13. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2000-07-01

    This is the fourth quarterly report on a new study to develop a ceramic membrane/metal joint. The first experiments using the La-Sr-Fe-O ceramic are reported. Some of the analysis performed on the samples obtained are commented upon. A set of experiments to characterize the mechanical strength and thermal fatigue properties of the joints has been designed and begun. Finite element models of joints used to model residual stresses are described.

  14. Battery utilizing ceramic membranes

    DOEpatents

    Yahnke, Mark S.; Shlomo, Golan; Anderson, Marc A.

    1994-01-01

    A thin film battery is disclosed based on the use of ceramic membrane technology. The battery includes a pair of conductive collectors on which the materials for the anode and the cathode may be spin coated. The separator is formed of a porous metal oxide ceramic membrane impregnated with electrolyte so that electrical separation is maintained while ion mobility is also maintained. The entire battery can be made less than 10 microns thick while generating a potential in the 1 volt range.

  15. Introduction of Artificial Pinning Center into PLD-YBCO Coated Conductor on IBAD and Self-Epitaxial CeO2 Buffered Metal Substrate

    SciTech Connect

    Kobayashi, H.; Yamada, Y.; Ishida, S.; Takahashi, K.; Konishi, M.; Ibi, A.; Miyata, S.; Kato, T.; Hirayama, T.; Shiohara, Y.

    2006-03-31

    In order to fabricate YBa2Cu3O7-x (YBCO) coated conductors with high critical current density Jc in magnetic fields, we fabricated YBCO coated conductors with artificial pinning centers by the pulsed laser deposition (PLD) method on a self epitaxial PLD-CeO2 layer and ion-beam assisted deposition (IBAD)-Gd2Zr2O7 (GZO) buffered Hastelloy tape. Artificial pinning centers were introduced by the PLD deposition using the yttria-stabilized zirconia (YSZ) oxide target (nano-dot method) and YBCO target including YSZ particles (mixed target method). In the experiments using YSZ oxide target, YSZ nano-dots were observed. They were approximately 15 nm in height and 10 nm to 70 nm in diameter. We found that the density of nano-dots was controlled by the number of laser pulses. These samples exhibited higher Jc than YBCO films in magnetic fields. Furthermore, a similar improvement of Jc was observed in the experiments using YBCO target including YSZ particles. TEM observation revealed that columnar nano-structure made of BaZrO3 was formed during YBCO deposition and it was effective for pinning. We call this new epitaxial nano-structure 'bamboo structure' from its anisotropic growth and morphology.

  16. Properties of YBCO on LaMnO3-capped IBAD MgO-templates without Homo-epitaxial MgO layer.

    SciTech Connect

    Aytug, Tolga; Paranthaman, Mariappan Parans; Kim, Kyunghoon; Zhang, Yifei; Cantoni, Claudia; Zuev, Yuri L; Goyal, Amit; Thompson, James R; Christen, David K

    2009-01-01

    Previously, it has been well established that in an IBAD architecture for coated conductors, (1) LaMnO3 (LMO) buffer layers are structurally and chemically compatible with an underlying homo-epitaxial MgO layer and (2) high current density YBCO films can be grown on these LMO templates. In the present work, the homo-epi MgO layer has been successfully eliminated and a LMO cap layer was grown directly on the IBAD (MgO) template. The performance of the LMO/IBAD (MgO) samples has been qualified by depositing 1 m-thick YBCO coatings by pulsed laser deposition. Electrical transport measurements of YBCO films on the standard (with homo-epi MgO) and simplified (without homo-epi MgO) IBAD architectures were carried out. The angular dependencies of critical current density (Jc) are similar for both IBAD architectures. XRD measurements indicate good, c-axis aligned YBCO films. Transmission electron microscopy (TEM) images reveal that microstructures of YBCO/LMO/IBAD (MgO) and YBCO/LMO/homo-epi MgO/IBAD (MgO) templates are similar. These results demonstrate the strong potential of using LMO as a single cap layer directly on IBAD (MgO) for the development of a simplified IBAD architecture.

  17. Alumina-based ceramic composite

    DOEpatents

    Alexander, K.B.; Tiegs, T.N.; Becher, P.F.; Waters, S.B.

    1996-07-23

    An improved ceramic composite comprising oxide ceramic particulates, nonoxide ceramic particulates selected from the group consisting of carbides, borides, nitrides of silicon and transition metals and mixtures thereof, and a ductile binder selected from the group consisting of metallic, intermetallic alloys and mixtures thereof is described. The ceramic composite is made by blending powders of the ceramic particulates and the ductile to form a mixture and consolidating the mixture of under conditions of temperature and pressure sufficient to produce a densified ceramic composite. 5 figs.

  18. Clinical application of bio ceramics

    NASA Astrophysics Data System (ADS)

    Anu, Sharma; Gayatri, Sharma

    2016-05-01

    Ceramics are the inorganic crystalline material. These are used in various field such as biomedical, electrical, electronics, aerospace, automotive and optical etc. Bio ceramics are the one of the most active areas of research. Bio ceramics are the ceramics which are biocompatible. The unique properties of bio ceramics make them an attractive option for medical applications and offer some potential advantages over other materials. During the past three decades, a number of major advances have been made in the field of bio ceramics. This review focuses on the use of these materials in variety of clinical scenarios.

  19. Ceramic electrolyte coating and methods

    DOEpatents

    Seabaugh, Matthew M.; Swartz, Scott L.; Dawson, William J.; McCormick, Buddy E.

    2007-08-28

    Aqueous coating slurries useful in depositing a dense coating of a ceramic electrolyte material (e.g., yttrium-stabilized zirconia) onto a porous substrate of a ceramic electrode material (e.g., lanthanum strontium manganite or nickel/zirconia) and processes for preparing an aqueous suspension of a ceramic electrolyte material and an aqueous spray coating slurry including a ceramic electrolyte material. The invention also includes processes for depositing an aqueous spray coating slurry including a ceramic electrolyte material onto pre-sintered, partially sintered, and unsintered ceramic substrates and products made by this process.

  20. Clinical evaluation of glass ceramic inlays (Dicor).

    PubMed

    Stenberg, R; Matsson, L

    1993-04-01

    The purpose of the study was to evaluate the clinical behavior of ceramic class-II inlays (Dicor) in the first 2 years after placement. As a reference, a similar number of dental amalgam restorations were followed up during the same period. Twenty-five inlays and 25 dental amalgams were placed on premolars and first molars of 20 and 19 patients (15-19 years old), respectively. The inlay preparations were made in accordance with the manufacturer's recommendations, and the inlays were produced by a licensed Dicor laboratory. The inlays were luted, using a glass ionomer cement. The dental amalgam preparations were made using standard class-II preparation techniques and filled with ANA 2000. The inlays were evaluated after 6, 12, and 24 months, and the dental amalgam restorations after 24 months, using the criteria suggested by Ryge. In addition, the 24-month examination included proximal recording of dental plaque and gingivitis. With the exception of two inlays that fractured during the observation period, all ceramic inlays showed excellent ratings for anatomic form, marginal discoloration, and marginal caries at all examinations. Two inlays showed minor marginal defects but were classified within the range of acceptance with no need for replacement. The two fractured inlays were replacements of earlier fractured dental amalgams. The clinical behavior of the dental amalgam restorations was in most respects similar to that of the ceramic inlays. Unlike the inlays, however, no dental amalgams fractured during the observation period.(ABSTRACT TRUNCATED AT 250 WORDS)

  1. Microscopic Evidence of a Crossover to a Low-Temperature Intermediate Valence State in YbCo2Zn20

    NASA Astrophysics Data System (ADS)

    Mito, Takeshi; Hara, Hiroki; Ishida, Takuma; Nakagawara, Keitaro; Koyama, Takehide; Ueda, Koichi; Kohara, Takao; Ishida, Kenji; Matsubayashi, Kazuyuki; Saiga, Yuta; Uwatoko, Yoshiya

    2013-10-01

    The low-temperature properties of YbCo2Zn20, which shows a giant specific heat at low temperatures, have been studied by the 59Co-nuclear quadrupole resonance (NQR) technique. The measurement of spin lattice relaxation rate reveals that Yb 4f-electrons unusually persist in a well-localized regime down to at least 0.3 K without ordering magnetically. With further lowering temperature, NQR frequency decreases below 0.2 K reflecting the low-temperature Fermi liquid state, even suggesting a crossover to an intermediate valence state in close proximity to the localized--delocalzied transition. We also compare the observed unique properties of YbCo2Zn20 with those of YbRh2Si2, which shows antiferromagnetic ordering at extremely low temperature.

  2. A simple multi-seeding approach to growth of large YBCO bulk with a diameter above 53 mm

    NASA Astrophysics Data System (ADS)

    Tang, Tian-wei; Wu, Dong-jie; Wu, Xing-da; Xu, Ke-Xi

    2015-12-01

    A successful simple multi-seeding approach to growing large size Y-Ba-C-O (YBCO) bulks is reported. Compared with the common single seeding method, our multi-seeding method is more efficient. By using four SmBa2Cu3O7-δ (Sm-123) seeds cut from a large size Sm-Ba-C-O (SmBCO) single domain, large YBCO samples up to 53 mm in diameter could be produced successfully and 100 mm diameter samples can also be grown. Experimental results show that the processing time can be shortened greatly by using this new approach, and the superconducting properties can also be improved. The Hall probe mapping shows that the trapped field distribution of 53 mm diameter multi-seeded sample is homogeneous and the peak value is up to 0.53 T. The magnetic levitation force density reaches to 14.7 N/cm2 (77 K, 0.5 T).

  3. Genotoxicity test of self-renovated ceramics in primary human peripheral lymphocytes.

    PubMed

    Hua, Nan; Zhu, Huifang; Zhuang, Jing; Chen, Liping

    2014-12-01

    Zirconia-based ceramics is widely used in dentistry. Different compositions of ceramics have different features. Our self-renovated ceramics become more machinable without scarifying its dental restoration properties after adjusting ratio of lanthanum phosphate (LaPO4)/yttrium oxide (Y2O3). In order to evaluate its safety, here, we tested its genotoxicity in primary human peripheral lymphocytes. The human lymphocytes cultured on three groups of different ratios of LaPO4/Y2O3 diphase ceramics for 6 days showed little effect of growth inhibition and similar effect of growth trend to the negative control. Furthermore, single-cell gel electrophoresis (comet assay) indicated that there was no significant difference of the value of tail moment between the tested ceramics and negative control, the IPS Empress II (P > 0.05). Our findings implicate that our self-renovated ceramics do not induce DNA damages in human peripheral lymphocytes and support their future clinic application.

  4. Fundamental tribological properties of ceramics

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.; Miyoshi, K.

    1985-01-01

    When a ceramic is brought into contact with itself, another ceramic, or a metal, strong bond forces can develop between the materials. Adhesion between a ceramic and itself or another solid are discussed from a theoretical consideration of the nature of the surfaces and experimentally by relating bond forces to the interface resulting from solid state contact. Elastic, plastic, and fracture behavior of ceramics in solid-state contact are discussed as they relate to friction and wear. The contact load necessary to initiate fracture in ceramics is shown to be appreciably reduced with tangential motion. Both friction and wear of ceramics are anisotropic and relate to crystal structure as with metals. Both free energy of oxide formation and the d valence bond character of metals are related to the friction and wear characteristics for metals in contact with ceramics. Lubrication is found to increase the critical load necessary to initiate fracture of ceramics with sliding or rubbing contact.

  5. Piezoelectric Ceramics and Their Applications

    ERIC Educational Resources Information Center

    Flinn, I.

    1975-01-01

    Describes the piezoelectric effect in ceramics and presents a quantitative representation of this effect. Explains the processes involved in the manufacture of piezoelectric ceramics, the materials used, and the situations in which they are applied. (GS)

  6. Microstructure and properties of ceramics

    NASA Technical Reports Server (NTRS)

    Hamano, K.

    1984-01-01

    The history of research into the microstructure and properties of ceramic ware is discussed; methods of producing ceramics with particular characteristics are investigated. Bubbles, sintering, cracks, and electron microscopy are discussed.

  7. Manufacture of YBCO Superconducting Flexible Tapes from Nanoparticle Films Derived from Sedimentation and by Flame Deposition of Nanoparticles from Solution

    SciTech Connect

    Wiesmann, Harold

    2008-02-24

    The objective of this CRADA was to develop the experimental and theoretical basis of a technology to produce yttrium barium copper oxide (YBCO) superconducting flexible tapes derived from nanoparticle metal oxide sols. The CRADA was a joint effort between Oxford Superconducting Technology, Brookhaven National Laboratory and Karpov Institute of Physical Chemistry. The effort was divided into three main tasks, the synthesis of a heteroepitaxial oxide buffer layer, and the manufacture of a flexible biaxially textured metallic substrate and the synthesis of a heteroepitaxial crystalline YBCO layer. The formation of a heteroepitaxial buffer layer was implemented using technology developed at the Karpov Institute of Physical Chemistry for the synthesis, stabilization and deposition of polymer stabilized nanoparticle metal oxide sols. Using this technology, flexible oriented RABiTS nickel tapes, manufactured and supplied by the CRADA partner, Oxford Superconducting Technology, Carteret, New Jersey, were coated with a film of metal oxide nanoparticles. After coating the RABiTS nickel tapes with the nanoparticle sols the nickel tape/nanoparticle composite structure was sintered in order to form a dense crystalline heteroepitaxial oxide layer on the surface of the tape, also known as a ‘buffer’ layer. The final phase of the research was the formation of a heteroepitaxial YBCO layer, grown on top of the metal oxide buffer layer. This work was scheduled to follow the development of the heteroepitaxial oxide buffer layer as described above. Three different polymer stabilized sols, yttrium hydroxide, Y(OH){sub 3}, copper hydroxide, Cu(OH){sub 2}, and barium fluoride, BaF{sub 2}, were synthesized and combined in the appropriate stoichiometric ratio. This metal oxide sol was then be deposited onto the buffer layer and reacted to form a crystalline heteroepitaxial YBCO film ranging from 1–5 microns thick.

  8. Ceramic automotive Stirling engine program

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The Ceramic Automotive Stirling Engine Program evaluated the application of advanced ceramic materials to an automotive Stirling engine. The objective of the program was to evaluate the technical feasibility of utilizing advanced ceramics to increase peak engine operating temperature, and to evaluate the performance benefits of such an increase. Manufacturing cost estimates were also developed for various ceramic engine components and compared with conventional metallic engine component costs.

  9. Ceramic Automotive Stirling Engine Program

    SciTech Connect

    Not Available

    1986-08-01

    The Ceramic Automotive Stirling Engine Program evaluated the application of advanced ceramic materials to an automotive Stirling engine. The objective of the program was to evaluate the technical feasibility of utilizing advanced ceramics to increase peak engine operating temperature, and to evaluate the performance benefits of such an increase. Manufacturing cost estimates were also developed for various ceramic engine components and compared with conventional metallic engine component costs.

  10. Ceramic microstructure and adhesion

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1984-01-01

    When a ceramic is brought into contact with a ceramic, a polymer, or a metal, strong bond forces can develop between the materials. The bonding forces will depend upon the state of the surfaces, cleanliness and the fundamental properties of the two solids, both surface and bulk. Adhesion between a ceramic and another solid are discussed from a theoretical consideration of the nature of the surfaces and experimentally by relating bond forces to interface resulting from solid state contact. Surface properties of ceramics correlated with adhesion include, orientation, reconstruction and diffusion as well as the chemistry of the surface specie. Where a ceramic is in contact with a metal their interactive chemistry and bond strength is considered. Bulk properties examined include elastic and plastic behavior in the surficial regions, cohesive binding energies, crystal structures and crystallographic orientation. Materials examined with respect to interfacial adhesive interactions include silicon carbide, nickel zinc ferrite, manganese zinc ferrite, and aluminum oxide. The surfaces of the contacting solids are studied both in the atomic or molecularly clean state and in the presence of selected surface contaminants.

  11. Ceramic combustor mounting

    DOEpatents

    Hoffman, Melvin G.; Janneck, Frank W.

    1982-01-01

    A combustor for a gas turbine engine includes a metal engine block including a wall portion defining a housing for a combustor having ceramic liner components. A ceramic outlet duct is supported by a compliant seal on the metal block and a reaction chamber liner is stacked thereon and partly closed at one end by a ceramic bypass swirl plate which is spring loaded by a plurality of circumferentially spaced, spring loaded guide rods and wherein each of the guide rods has one end thereof directed exteriorly of a metal cover plate on the engine block to react against externally located biasing springs cooled by ambient air and wherein the rod spring support arrangement maintains the stacked ceramic components together so that a normal force is maintained on the seal between the outlet duct and the engine block under all operating conditions. The support arrangement also is operative to accommodate a substantial difference in thermal expansion between the ceramic liner components of the combustor and the metal material of the engine block.

  12. FATIGUE OF DENTAL CERAMICS

    PubMed Central

    Zhang, Yu; Sailer, Irena; Lawn, Brian R

    2013-01-01

    Objectives Clinical data on survival rates reveal that all-ceramic dental prostheses are susceptible to fracture from repetitive occlusal loading. The objective of this review is to examine the underlying mechanisms of fatigue in current and future dental ceramics. Data/sources The nature of various fatigue modes is elucidated using fracture test data on ceramic layer specimens from the dental and biomechanics literature. Conclusions Failure modes can change over a lifetime, depending on restoration geometry, loading conditions and material properties. Modes that operate in single-cycle loading may be dominated by alternative modes in multi-cycle loading. While post-mortem examination of failed prostheses can determine the sources of certain fractures, the evolution of these fractures en route to failure remains poorly understood. Whereas it is commonly held that loss of load-bearing capacity of dental ceramics in repetitive loading is attributable to chemically-assisted 'slow crack growth' in the presence of water, we demonstrate the existence of more deleterious fatigue mechanisms, mechanical rather than chemical in nature. Neglecting to account for mechanical fatigue can lead to gross overestimates in predicted survival rates. Clinical significance Strategies for prolonging the clinical lifetimes of ceramic restorations are proposed based on a crack-containment philosophy. PMID:24135295

  13. Ceramic impregnated superabrasives

    DOEpatents

    Radtke, Robert P.; Sherman, Andrew

    2009-02-10

    A superabrasive fracture resistant compact is formed by depositing successive layers of ceramic throughout the network of open pores in a thermally stable self-bonded polycrystalline diamond or cubic boron nitride preform. The void volume in the preform is from approximately 2 to 10 percent of the volume of the preform, and the average pore size is below approximately 3000 nanometers. The preform is evacuated and infiltrated under at least about 1500 pounds per square inch pressure with a liquid pre-ceramic polymerizable precursor. The precursor is infiltrated into the preform at or below the boiling point of the precursor. The precursor is polymerized into a solid phase material. The excess is removed from the outside of the preform, and the polymer is pyrolized to form a ceramic. The process is repeated at least once more so as to achieve upwards of 90 percent filling of the original void volume. When the remaining void volume drops below about 1 percent the physical properties of the compact, such as fracture resistance, improve substantially. Multiple infiltration cycles result in the deposition of sufficient ceramic to reduce the void volume to below 0.5 percent. The fracture resistance of the compacts in which the pores are lined with formed in situ ceramic is generally at least one and one-half times that of the starting preforms.

  14. Ceramics with Different Additives

    NASA Astrophysics Data System (ADS)

    Wang, Juanjuan; Feng, Lajun; Lei, Ali; Zhao, Kang; Yan, Aijun

    2014-09-01

    Li2CO3, MgCO3, BaCO3, and Bi2O3 dopants were introduced into CaCu3Ti4O12 (CCTO) ceramics in order to improve the dielectric properties. The CCTO ceramics were prepared by conventional solid-state reaction method. The phase structure, microstructure, and dielectric behavior were carefully investigated. The pure structure without any impurity phases can be confirmed by the x-ray diffraction patterns. Scanning Electron Microscopy (SEM) analysis illuminated that the grains of Ca0.90Li0.20Cu3Ti4O12 ceramics were greater than that of pure CCTO. It was important for the properties of the CCTO ceramics to study the additives in complex impedance spectroscopy. It was found that the Ca0.90Li0.20Cu3Ti4O12 ceramics had the higher permittivity (>45000), the lower dielectric loss (<0.025) than those of CCTO at 1 kHz at room temperature and good temperature stability from -30 to 75 °C.

  15. An electron backscatter diffraction investigation of crystallographic orientations of embedded nanoparticles within melt-textured YBCO high temperature superconductors

    NASA Astrophysics Data System (ADS)

    Koblischka-Veneva, A.; Koblischka, M. R.; Babu, N. Hari; Cardwell, D. A.; Shlyk, L.; Krabbes, G.

    2006-07-01

    Microstructures of melt-textured YBCO samples with embedded nanosized particles of Y2BaCuO5 (Y-211) and Y2Ba4CuMOx (M-2411 with M = U,Zr) are analysed by means of electron backscatter diffraction (EBSD). With the recent developments of the EBSD technique, we can directly measure the crystallographic orientation of the embedded nanoparticles, employing a spatial resolution of about 40 nm. The high image quality of the Kikuchi patterns allows true three-phase (YBCO, Y-211 and M-2411) scans to be performed. The Y-211 particles do not exhibit any preferred orientation, even if their size is considerably reduced, to the 100 nm range. The size reduction reduces the negative influence of the Y-211 particles on the YBCO matrix, however. U-2411 particles, which are formed during the processing stage, do not show any orientation, and with increasing concentration, some texture develops. In contrast to this, embedded Zr-2411 particles are fully oriented in the (001) orientation according to the surrounding superconducting matrix.

  16. Role of nano and micron-sized inclusions on the oxygen controlled preform optimized infiltration growth processed YBCO superconductors

    NASA Astrophysics Data System (ADS)

    Pavan Kumar Naik, S.; Bai, V. Seshu

    2017-02-01

    In the present work, with the aim of improving the local flux pinning at the unit cell level in the YBa2Cu3O7-δ (YBCO) bulk superconductors, 20 wt% of nanoscale Sm2O3 and micron sized (Nd, Sm, Gd)2BaCuO5 secondary phase particles were added to YBCO and processed in oxygen controlled preform optimized infiltration growth process. Nano Dispersive Sol Casting method is employed to homogeneously distribute the nano Sm2O3 particles of 30-50 nm without any agglomeration in the precursor powder. Microstructural investigations on doped samples show the chemical fluctuations as annuli cores in the 211 phase particles. The introduction of mixed rare earth elements at Y-site resulted in compositional fluctuations in the superconducting matrix. The associated lattice mismatch defects have provided flux pinning up to large magnetic fields. Magnetic field dependence of current density (Jc(H)) at different temperatures revealed that the dominant pinning mechanism is caused by spatial variations of critical temperatures, due to the spatial fluctuations in the matrix composition. As the number of rare earth elements increased in the YBCO, the peak field position in the scaling of the normalized pinning force density (Fp/Fp max) significantly gets shifted towards the higher fields. The curves of Jc(H) and Fp/Fp max at different temperatures clearly indicate the LRE substitution for LRE' or Ba-sites for δTc pinning.

  17. Ceramic coatings on smooth surfaces

    NASA Technical Reports Server (NTRS)

    Miller, R. A. (Inventor); Brindley, W. J. (Inventor); Rouge, C. J. (Inventor)

    1991-01-01

    A metallic coating is plasma sprayed onto a smooth surface of a metal alloy substitute or on a bond coating. An initial thin ceramic layer is low pressure sprayed onto the smooth surface of the substrate or bond coating. Another ceramic layer is atmospheric plasma sprayed onto the initial ceramic layer.

  18. Assessment of ceramic membrane filters

    SciTech Connect

    Ahluwalia, R.K.; Geyer, H.K.; Im, K.H.

    1995-08-01

    The objectives of this project include the development of analytical models for evaluating the fluid mechanics of membrane coated, dead-end ceramic filters, and to determine the effects of thermal and thermo-chemical aging on the material properties of emerging ceramic hot gas filters. A honeycomb cordierite monolith with a thin ceramic coating and a rigid candle filter were evaluated.

  19. Ceramic composites: Enabling aerospace materials

    NASA Technical Reports Server (NTRS)

    Levine, S. R.

    1992-01-01

    Ceramics and ceramic matrix composites (CMC) have the potential for significant impact on the performance of aerospace propulsion and power systems. In this paper, the potential benefits are discussed in broad qualitative terms and are illustrated by some specific application case studies. The key issues in need of resolution for the potential of ceramics to be realized are discussed.

  20. Ceramic tamper-revealing seals

    DOEpatents

    Kupperman, D.S.; Raptis, A.C.; Sheen, S.H.

    1992-12-08

    A flexible metal or ceramic cable is described with composite ceramic ends, or a U-shaped ceramic connecting element attached to a binding element plate or block cast from alumina or zirconium, and connected to the connecting element by shrink fitting. 7 figs.

  1. Ceramic technology for automotive turbines

    NASA Technical Reports Server (NTRS)

    Mclean, A. F.

    1982-01-01

    The paper presents an update on ceramic technology for automotive turbines. Progress in research and development of improved ceramics is reviewed, including approaches for assessing time-dependent strength characteristics. Processes for making shapes are discussed, and the design and testing of selected ceramic turbine components are reviewed.

  2. Artificial Voids In Ceramic Materials

    NASA Technical Reports Server (NTRS)

    Roth, Don J.; Generazio, Edward R.; Baaklini, George Y.

    1988-01-01

    Method for creating voids in ceramic specimens developed. Silicon carbide and silicon nitride are high-temperature structural ceramic materials considered for applications in advanced gas-turbine engines. Ability to detect and characterize voids (by sizes, shapes, and locations) in structural ceramics vital for increasing strengths and reliabilities of materials. Small holes made deliberately to help quantify techniques of nondestructive evaluation.

  3. Innovative grinding wheel design for cost-effective machining of advanced ceramics

    SciTech Connect

    Licht, R.H.; Kuo, P.; Liu, S.; Murphy, D.; Picone, J.W.; Ramanath, S.

    2000-05-01

    This Final Report covers the Phase II Innovative Grinding Wheel (IGW) program in which Norton Company successfully developed a novel grinding wheel for cost-effective cylindrical grinding of advanced ceramics. In 1995, Norton Company successfully completed the 16-month Phase I technical effort to define requirements, design, develop, and evaluate a next-generation grinding wheel for cost-effective cylindrical grinding of advanced ceramics using small prototype wheels. The Phase II program was initiated to scale-up the new superabrasive wheel specification to larger diameters, 305-mm to 406-mm, required for most production grinding of cylindrical ceramic parts, and to perform in-house and independent validation grinding tests.

  4. Ceramic regenerator program

    NASA Technical Reports Server (NTRS)

    Franklin, Jerrold E.

    1991-01-01

    The feasibility of fabricating an Air Turbo Ramjet (ATR) regenerator containing intricate hydraulic passages from a ceramic material in order to allow operation with high temperature combustion gas and to reduce weight as compared with metallic materials was demonstrated. Platelet technology, ceramic tape casting, and multilayer ceramic packaging techniques were used in this fabrication of subscale silicon nitride components. Proof-of-concept demonstrations were performed to simulate a methane cooled regenerator for an ATR engine. The regenerator vane was designed to operate at realistic service conditions, i.e., 600 psi in a 3500 R (3040 F), 500 fps combustion gas environment. A total of six regenerators were fabricated and tested. The regenerators were shown to be able to withstand internal pressurization to 1575 psi. They were subjected to testing in 500 fps, 3560 R (3100 F) air/propane combustion products and were operated satisfactorily for an excess of 100 hr and 40 thermal cycles which exceeded 2460 R (2000 F).

  5. Ceramic vane drive joint

    DOEpatents

    Smale, Charles H.

    1981-01-01

    A variable geometry gas turbine has an array of ceramic composition vanes positioned by an actuating ring coupled through a plurality of circumferentially spaced turbine vane levers to the outer end of a metallic vane drive shaft at each of the ceramic vanes. Each of the ceramic vanes has an end slot of bow tie configuration including flared end segments and a center slot therebetween. Each of the vane drive shafts has a cross head with ends thereof spaced with respect to the sides of the end slot to define clearance for free expansion of the cross head with respect to the vane and the cross head being configured to uniformly distribute drive loads across bearing surfaces of the vane slot.

  6. Microwave sintering of ceramics

    SciTech Connect

    Snyder, W.B.

    1989-01-01

    Successful adaptation of microwave heating to the densification of ceramic materials require a marriage of microwave and materials technologies. Using an interdisciplinary team of microwave and materials engineers, we have successfully demonstrated the ability to density ceramic materials over a wide range of temperatures. Microstructural evolution during microwave sintering has been found to be significantly different from that observed in conventional sintering. Our results and those of others indicate that microwave sintering has the potential to fabricate components to near net shape with mechanical properties equivalent to hot pressed or hot isostatically pressed material. 6 refs., 11 figs.

  7. Ceramic component for electrodes

    DOEpatents

    Marchant, David D.

    1979-01-01

    A ceramic component suitable for preparing MHD generator electrodes consists of HfO.sub.2 and sufficient Tb.sub.4 O.sub.7 to stabilize at least 60 volume percent of the HfO.sub.2 into the cubic structure. The ceramic component may also contain a small amount of PrO.sub.2, Yb.sub.2 O.sub.3 or a mixture of both to improve stability and electronic conductivity of the electrode. The component is highly resistant to corrosion by molten potassium seed and molten coal slag in the MHD fluid and exhibits both ionic and electronic conductivity.

  8. Ceramic breeder materials

    SciTech Connect

    Johnson, C.E.; Kummerer, K.R.; Roth, E.

    1987-01-01

    Ceramic materials are under investigation as potential breeder material in fusion reactors. This paper will review candidate materials with respect to fabrication routes and characterization, properties in as-fabricated and irradiated condition, and experimental results from laboratory and inpile investigations on tritium transport and release. Also discussed are the resources of beryllium, which is being considered as a neutron multiplier. The comparison of ceramic properties that is attempted here aims at the identification of the most-promising material for use in a tritium breeding blanket. 82 refs., 12 figs., 5 tabs.

  9. Environment Conscious Ceramics (Ecoceramics)

    NASA Technical Reports Server (NTRS)

    Singh, Mrityunjay; Levine, Stanley R. (Technical Monitor)

    2000-01-01

    Environment conscious ceramics (Ecoceramics) are a new class of materials, which can be produced with renewable natural resources (wood) or wood wastes (wood sawdust). Silicon carbide-based ecoceramics have been fabricated by reactive infiltration of carbonaceous preforms by molten silicon or silicon-refractory metal alloys. These carbonaceous preforms have been fabricated by pyrolysis of solid wood bodies at 1000 C. The fabrication approach, microstructure, and mechanical properties of SiC-based ecoceramics are presented. Ecoceramics have tailorable properties and behave like ceramic materials manufactured by conventional approaches.

  10. Performance of Dental Ceramics

    PubMed Central

    Rekow, E.D.; Silva, N.R.F.A.; Coelho, P.G.; Zhang, Y.; Guess, P.; Thompson, V.P.

    2011-01-01

    The clinical success of modern dental ceramics depends on an array of factors, ranging from initial physical properties of the material itself, to the fabrication and clinical procedures that inevitably damage these brittle materials, and the oral environment. Understanding the influence of these factors on clinical performance has engaged the dental, ceramics, and engineering communities alike. The objective of this review is to first summarize clinical, experimental, and analytic results reported in the recent literature. Additionally, it seeks to address how this new information adds insight into predictive test procedures and reveals challenges for future improvements. PMID:21224408

  11. Why ceramic engines?

    NASA Technical Reports Server (NTRS)

    Stadler, H. L.

    1984-01-01

    Oil is still a problem for the U.S. and its allies. Transportation uses 61 percent of U.S. oil and its share is increasing, so more efficient technology should be concentrated there. Trucks' share of oil use is increasing because they are already much more efficient than autos. The primary truck opportunities are streamlining, more efficient engines, and shifting freight to railroads. More efficient engines are possible using ceramics to allow elimination of cooling systems and better use of waste exhaust heat. A 60 percent improvement seems possible if ceramics can be made tough enough and durable enough.

  12. Battery utilizing ceramic membranes

    DOEpatents

    Yahnke, M.S.; Shlomo, G.; Anderson, M.A.

    1994-08-30

    A thin film battery is disclosed based on the use of ceramic membrane technology. The battery includes a pair of conductive collectors on which the materials for the anode and the cathode may be spin coated. The separator is formed of a porous metal oxide ceramic membrane impregnated with electrolyte so that electrical separation is maintained while ion mobility is also maintained. The entire battery can be made less than 10 microns thick while generating a potential in the 1 volt range. 2 figs.

  13. Supported microporous ceramic membranes

    DOEpatents

    Webster, E.; Anderson, M.

    1993-12-14

    A method for the formation of microporous ceramic membranes onto a porous support includes placing a colloidal suspension of metal or metal oxide particles on one side of the porous support and exposing the other side of the porous support to a drying stream of gas or a reactive gas stream so that the particles are deposited on the drying side of the support as a gel. The gel so deposited can be sintered to form a supported ceramic membrane useful for ultrafiltration, reverse osmosis, or molecular sieving having mean pore sizes less than 100 Angstroms. 4 figures.

  14. Supported microporous ceramic membranes

    DOEpatents

    Webster, Elizabeth; Anderson, Marc

    1993-01-01

    A method for permformation of microporous ceramic membranes onto a porous support includes placing a colloidal suspension of metal or metal oxide particles on one side of the porous support and exposing the other side of the porous support to a drying stream of gas or a reactive gas stream so that the particles are deposited on the drying side of the support as a gel. The gel so deposited can be sintered to form a supported ceramic membrane useful for ultrafiltration, reverse osmosis, or molecular sieving having mean pore sizes less than 100 Angstroms.

  15. Influence of resin cement shade on the color and translucency of ceramic veneers

    PubMed Central

    HERNANDES, Daiana Kelly Lopes; ARRAIS, Cesar Augusto Galvão; de LIMA, Erick; CESAR, Paulo Francisco; RODRIGUES, José Augusto

    2016-01-01

    ABSTRACT Objective This in vitro study evaluated the effect of two different shades of resin cement (RC- A1 and A3) layer on color change, translucency parameter (TP), and chroma of low (LT) and high (HT) translucent reinforced lithium disilicate ceramic laminates. Material and Methods One dual-cured RC (Variolink II, A1- and A3-shade, Ivoclar Vivadent) was applied to 1-mm thick ceramic discs to create thin RC films (100 µm thick) under the ceramics. The RC was exposed to light from a LED curing unit. Color change (ΔE) of ceramic discs was measured according to CIEL*a*b* system with a standard illuminant D65 in reflectance mode in a spectrophotometer, operating in the light range of 360-740 nm, equipped with an integrating sphere. The color difference between black (B) and white (W) background readings was used for TP analysis, while chroma was calculated by the formula C* ab=(a*2+b*2)½. ΔE of 3.3 was set as the threshold of clinically unacceptable. The results were evaluated by two-way ANOVA followed by Tukey's post hoc test. Results HT ceramics showed higher ΔE and higher TP than LT ceramics. A3-shade RC promoted higher ΔE than A1-shade cement, regardless of the ceramic translucency. No significant difference in TP was noted between ceramic discs with A1- and those with A3-shade cement. Ceramic with underlying RC showed lower TP than discs without RC. HT ceramics showed lower chroma than LT ceramics, regardless of the resin cement shade. The presence of A3-shade RC resulted in higher chroma than the presence of A1-shade RC. Conclusions Darker underlying RC layer promoted more pronounced changes in ceramic translucency, chroma, and shade of high translucent ceramic veneers. These differences may not be clinically differentiable. PMID:27556211

  16. [Ceramic couplings in orthopedic surgery].

    PubMed

    Thomsen, M; Willmann, G

    2003-01-01

    Ceramic materials have been used as a coupling in total hip arthroplasty since the 1970s to solve the problem of polyethylene particle disease. Several problems with the material and the design have been identified and solved. Using inlays and ceramic heads of the latest generation offers the possibility of reducing the wear rate to as low as 0.001 mm per year. The problem of ceramic fractures is rare. Recently due to the manufacturing process some zirconia ceramic heads have been problematic. New developments with other ceramics are discussed.

  17. Effect of grain size on actuator properties of piezoelectric ceramics

    NASA Astrophysics Data System (ADS)

    Hackenberger, Wesley S.; Pan, Ming-Jen; Vedula, Venkata; Pertsch, Patrick; Cao, Wenwu; Randall, Clive A.; Shrout, Thomas R.

    1998-07-01

    Properties of piezoelectric ceramics important for actuator applications have been measured as a function of grain size. Fine grain piezoelectrics (<=1 μm) have been found to exhibit improved machinability and increased mechanical strength over conventional materials. Actuators made from fine grain ceramic are, therefore, expected to have improved reliability, higher driving fields, and lower driving voltages (from thinner layers in stacked or co-fired actuators) over devices fabricated from conventional materials. TRS Ceramics in collaboration with the Pennsylvania State University's Materials Research Laboratory, has developed fine grain piezoelectric ceramics with minimal or no reduction in piezoactivity. New chemical doping strategies designed to compensate ferroelectric domain clamping effects from grain boundaries have been successful in yielding submicron grain sized ceramics with both low and high field properties equivalent to conventional materials. In the case of Type II ceramics, reduced grain size results in a very stable domain state with respect to both electric field and compressive prestress. Work is in progress to develop both epoxy bonded stack and co-fired actuators from fine grain piezoelectrics.

  18. Tribological properties of structural ceramics

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.; Miyoshi, K.

    1985-01-01

    The tribological and lubricated behavior of both oxide and nonoxide ceramics are reviewed in this chapter. Ceramics are examined in contact with themselves, other harder materials and metals. Elastic, plastic and fracture behavior of ceramics in solid state contact is discussed. The contact load necessary to initiate fracture in ceramics is shown to be appreciably reduced with tangential motion. Both friction and wear of ceramics are anisotropic and relate to crystal structure as has been observed with metals. Grit size effects in two and three body abrasive wear are observed for ceramics. Both free energy of oxide formation and the d valence bond character of metals are related to the friction and wear characteristics for metals in contact with ceramics. Surface contaminants affect friction and adhesive wear. For example, carbon on silicon carbide and chlorine on aluminum oxide reduce friction while oxygen on metal surfaces in contact with ceramics increases friction. Lubrication increases the critical load necessary to initiate fracture of ceramics both in indentation and with sliding or rubbing. Ceramics compositions both as coatings and in composites are described for the high temperature lubrication of both alloys and ceramics.

  19. Light-weight ceramic insulation

    NASA Technical Reports Server (NTRS)

    Hsu, Ming-Ta S. (Inventor); Chen, Timothy S. (Inventor)

    2002-01-01

    Ultra-high temperature, light-weight, ceramic insulation such as ceramic tile is obtained by pyrolyzing a siloxane gel derived from the reaction of at least one organo dialkoxy silane and at least one tetralkoxy silane in an acid or base liquid medium. The reaction mixture of the tetra- and dialkoxy silanes may contain also an effective amount of a mono- or trialkoxy silane to obtain the siloxane gel. The siloxane gel is dried at ambient pressures to form a siloxane ceramic precursor without significant shrinkage. The siloxane ceramic precursor is subsequently pyrolyzed, in an inert atmosphere, to form the black ceramic insulation comprising atoms of silicon, carbon and oxygen. The ceramic insulation, can be characterized as a porous, uniform ceramic tile resistant to oxidation at temperatures ranging as high as 1700.degree. C. and is particularly useful as lightweight tiles for spacecraft and other high-temperature insulation applications.

  20. Metal to ceramic sealed joint

    DOEpatents

    Lasecki, J.V.; Novak, R.F.; McBride, J.R.

    1991-08-27

    A metal to ceramic sealed joint which can withstand wide variations in temperature and maintain a good seal is provided for use in a device adapted to withstand thermal cycling from about 20 to about 1000 degrees C. The sealed joint includes a metal member, a ceramic member having an end portion, and an active metal braze forming a joint to seal the metal member to the ceramic member. The joint is positioned remote from the end portion of the ceramic member to avoid stresses at the ends or edges of the ceramic member. The sealed joint is particularly suited for use to form sealed metal to ceramic joints in a thermoelectric generator such as a sodium heat engine where a solid ceramic electrolyte is joined to metal parts in the system. 11 figures.

  1. Metal to ceramic sealed joint

    DOEpatents

    Lasecki, John V.; Novak, Robert F.; McBride, James R.

    1991-01-01

    A metal to ceramic sealed joint which can withstand wide variations in temperature and maintain a good seal is provided for use in a device adapted to withstand thermal cycling from about 20 to about 1000 degrees C. The sealed joint includes a metal member, a ceramic member having an end portion, and an active metal braze forming a joint to seal the metal member to the ceramic member. The joint is positioned remote from the end portion of the ceramic member to avoid stresses at the ends or edges of the ceramic member. The sealed joint is particularly suited for use to form sealed metal to ceramic joints in a thermoelectric generator such as a sodium heat engine where a solid ceramic electrolyte is joined to metal parts in the system.

  2. Temperature Rise during Resin Composite Polymerization under Different Ceramic Restorations

    PubMed Central

    Yondem, Isa; Altintas, Subutay Han; Usumez, Aslihan

    2011-01-01

    Objectives: The purpose of this study was to measure temperature increase induced by various light polymerizing units during resin composite polymerization beneath one of three types of ceramic restorations. Methods: The resin composite (Variolink II) was polymerized between one of three different ceramic specimens (zirconium oxide, lithium disilicate, feldspathic) (diameter 5 mm, height 2 mm) and a dentin disc (diameter 5 mm, height 1 mm) with a conventional halogen light, a high intensity halogen light, or an LED unit. The temperature rise was measured under the dentin disc with a J-type thermocouple wire connected to a data logger. Ten measurements were carried out for each group. The difference between the initial and highest temperature readings was taken and the 10 calculated temperature changes were averaged to determine the mean value in temperature rise. Two way analysis of variance (ANOVA) was used to analyze the data (polymerizing unit, ceramic brand) for significant differences. The Tukey HSD test was used to perform multiple comparisons (α=.05). Results: Temperature rise did not vary significantly depending on the light polymerizing unit used (P=.16), however, the type of ceramic system showed a significant effect on temperature increases (P<.01). There were no statistically significant differences between lithium disilicate and feldspathic ceramic systems (P >.05); in comparison, the resin composite polymerized under the zirconium oxide ceramic system induced a significantly lower temperature increase than the other ceramic systems tested (P<.05) Conclusions: The resin composite polymerized beneath zirconium oxide ceramic system induced significantly smaller temperature changes. The maximal temperature increase detected in all groups in this study was not viewed as critical for pulpal health. PMID:21769272

  3. High Throughput of Reel-to-reel MOCVD-YBCO on Different CSD-and MOCVD-buffered Cube Textured Ni-substrates

    NASA Astrophysics Data System (ADS)

    Muydinov, Ruslan; Stadel, Oliver; Falter, Martina; BŠcker, Michael

    Cheap chemical approaches: CSD/MOD and MOCVD were used and demonstrated to be feasible in 2G-wire production. New reel-to-reel MOCVD pilot system with higher throughput was examined, tuned and used in all YBCO depositions as well as for MgO, LMO, YSZ and CeO2 buffer layers fabrication. YBCO deposition process was found to be stable either at 10 m/h on 50 m long tapes or at 20 m/h on 100 m long tapes. All-layers-by-MOCVD approach allowed to get critical current up to Ic max > 90A/cm-width. On a single CSD-LZO (lanthanum zirconate) buffered Ni-alloy tapes 400 nm thick YBCO films with critical current density up to jc max = 1.5 MA/cm2 were obtained. On the basis of single CSD-LZO-buffered tapes, some multiple buffer sandwiches were created and compared in the same YBCO deposition. The best result was reached on CVD-CeO2/1×CSD-LZO/Ni5W buffer oxide system and showed for 650 nm thick YBCO rather stable over 2.5 m length Ic = 80-90 A.

  4. Microporous alumina ceramic membranes

    DOEpatents

    Anderson, M.A.; Guangyao Sheng.

    1993-05-04

    Several methods are disclosed for the preparation microporous alumina ceramic membranes. For the first time, porous alumina membranes are made which have mean pore sizes less than 100 Angstroms and substantially no pores larger than that size. The methods are based on improved sol-gel techniques.

  5. Coated ceramic breeder materials

    DOEpatents

    Tam, Shiu-Wing; Johnson, Carl E.

    1987-04-07

    A breeder material for use in a breeder blanket of a nuclear reactor is disclosed. The breeder material comprises a core material of lithium containing ceramic particles which has been coated with a neutron multiplier such as Be or BeO, which coating has a higher thermal conductivity than the core material.

  6. Silicon carbide ceramic production

    NASA Technical Reports Server (NTRS)

    Suzuki, K.; Shinohara, N.

    1984-01-01

    A method to produce sintered silicon carbide ceramics in which powdery carbonaceous components with a dispersant are mixed with silicon carbide powder, shaped as required with or without drying, and fired in nonoxidation atmosphere is described. Carbon black is used as the carbonaceous component.

  7. Microporous alumina ceramic membranes

    DOEpatents

    Anderson, Marc A.; Sheng, Guangyao

    1993-01-01

    Several methods are disclosed for the preparation microporous alumina ceramic membranes. For the first time, porous alumina membranes are made which have mean pore sizes less than 100 Angstroms and substantially no pores larger than that size. The methods are based on improved sol-gel techniques.

  8. Microwave processing of ceramics

    SciTech Connect

    Katz, J.D.

    1993-01-01

    Recent work in the areas of microwave processing and joining of ceramics is briefly reviewed. Advantages and disadvantages of microwave processing as well as some of the current issues in the field are discussed. Current state and potential for future commercialization of this technology is also addressed.

  9. Microwave processing of ceramics

    SciTech Connect

    Katz, J.D.

    1993-04-01

    Recent work in the areas of microwave processing and joining of ceramics is briefly reviewed. Advantages and disadvantages of microwave processing as well as some of the current issues in the field are discussed. Current state and potential for future commercialization of this technology is also addressed.

  10. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2001-05-01

    The mechanical properties of model systems were analyzed. A reasonably accurate finite element model was implemented and a rational metric to predict the strength of ceramic/metal concentrical joints was developed. The mode of failure of the ceramic/metal joints was determined and the importance of the mechanical properties of the braze material was assessed. Thermal cycling experiments were performed on the model systems and the results were discussed. Additionally, experiments using the concept of placing diffusion barriers on the ceramic surface to limit the extent of the reaction with the braze were performed. It was also observed that the nature and morphology of the reaction zone depends greatly on the nature of the perovskite structure being used. From the experiments, it is observed that the presence of Cr in the Fe-occupied sites decreases the tendency of Fe to segregate and to precipitate out of the lattice. In these new experiments, Ni was observed to play a major role in the decomposition of the ceramic substrate.

  11. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendfra Nagabhushana

    2001-07-01

    The mechanical properties of model systems were analyzed. A reasonably accurate finite element model was implemented and a rational metric to predict the strength of ceramic/metal concentrical joints was developed. The mode of failure of the ceramic/metal joints was determined and the importance of the mechanical properties of the braze material was assessed. Thermal cycling experiments were performed on the model systems and the results were discussed. Additionally, experiments using the concept of placing diffusion barriers on the ceramic surface to limit the extent of the reaction with the braze were performed. It was also observed that the nature and morphology of the reaction zone depends greatly on the nature of the perovskite structure being used. From the experiments, it is observed that the presence of Cr in the Fe-occupied sites decreases the tendency of Fe to segregate and to precipitate out of the lattice. In these new experiments, Ni was observed to play a major role in the decomposition of the ceramic substrate.

  12. Ceramic Coating Method

    DTIC Science & Technology

    2002-07-02

    platinum, protactinium , rhenium, chemically stable in oxygen or other oxidizing atmospheres. rhodium; ruthenium, samarium, scandium, silicon, tantalum; 20...high "mismatch" platinum, protactinium , rhenium, and tantalum braze layer, 30 between ceramic (e.g., A12O3 or ZrO2 ) and carbon steel, the lower-melting

  13. Durability of ceramic filters

    SciTech Connect

    Alvin, M.A.; Tressler, R.E.; Lippert, T.E.; Diaz, E.S.; Smeltzer, E.E.

    1994-10-01

    The objectives of this program are to identify the potential long-term thermal/chemical effects that advanced coal-based power generating systems have on the stability of porous ceramic filter materials, as well as to assess the influence of these effects on filter operating performance and life.

  14. Coated ceramic breeder materials

    DOEpatents

    Tam, Shiu-Wing; Johnson, Carl E.

    1987-01-01

    A breeder material for use in a breeder blanket of a nuclear reactor is disclosed. The breeder material comprises a core material of lithium containing ceramic particles which has been coated with a neutron multiplier such as Be or BeO, which coating has a higher thermal conductivity than the core material.

  15. Refractory ceramic fibers

    Integrated Risk Information System (IRIS)

    Refractory ceramic fibers ; CASRN Not found 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 Noncarcino

  16. Microstructure of Josephson junctions: Effect on supercurrent transport in YBCO grain boundary and barrier layer junctions

    SciTech Connect

    Merkle, K.L.; Huang, Y.

    1998-01-01

    The electric transport of high-temperature superconductors, such as YBa{sub 2}Cu{sub 3}O{sub 7{minus}x} (YBCO), can be strongly restricted by the presence of high-angle grain boundaries (GB). This weak-link behavior is governed by the macroscopic GB geometry and the microscopic grain boundary structure and composition at the atomic level. Whereas grain boundaries present a considerable impediment to high current applications of high T{sub c} materials, there is considerable commercial interest in exploiting the weak-link-nature of grain boundaries for the design of microelectronic devices, such as superconducting quantum interference devices (SQUIDs). The Josephson junctions which form the basis of this technology can also be formed by introducing artificial barriers into the superconductor. The authors have examined both types of Josephson junctions by EM techniques in an effort to understand the connection between microstructure/chemistry and electrical transport properties. This knowledge is a valuable resource for the design and production of improved devices.

  17. Irreversible properties of YBCO thick films deposited by liquid phase epitaxy on single crystalline substrates

    NASA Astrophysics Data System (ADS)

    Vostner, A.; Tönies, S.; Weber, H. W.; Cheng, Y. S.; Kurumovic, A.; Evetts, J. E.; Mennema, S. H.; Zandbergen, H. W.

    2003-10-01

    We report on the field and temperature dependence of the critical transport current density Jc, the angular dependence of the transport current at various external magnetic fields and the irreversibility fields in YBa2Cu3O7-delta (Y-123) thick films prepared by liquid phase epitaxy (LPE). A comparison of the irreversible properties between specimens produced with and without silver additions to the melt is also presented. Transmission electron microscopy (TEM) was employed to obtain information on the correlation between the transport properties and the microstructure. The samples were deposited either directly on NdGaO3 (NGO) or on seeded (100) MgO substrates, where a 200 nm thin YBCO film deposited by pulsed laser deposition (PLD) acts as seed layer for the LPE process. The final thickness of the Y-123 layer is of the order of 1 µm for the NGO and between 2 and 10 µm for the MgO samples. The critical current densities reach 3 × 109 A m-2 at zero field and 77 K in the best case.

  18. Fabrication of YSZ buffer layer by single source MOCVD technique for YBCO coated conductor

    NASA Astrophysics Data System (ADS)

    Jun, Byung-Hyuk; Sun, Jong-Won; Kim, Ho-Jin; Lee, Dong-Wook; Jung, Choong-Hwan; Park, Soon-Dong; Kim, Chan-Joong

    2003-10-01

    Yttria stabilized zirconia (YSZ) buffer layers were deposited by a metal organic chemical vapor deposition technique using a single liquid source for the application of YBa 2Cu 3O 7- δ (YBCO) coated conductor. Y:Zr mole ratio was 0.2:0.8, and tetrahydrofuran (THF) was used as a solvent. The (1 0 0) single crystal MgO substrate was used for searching the deposition conditions. Bi-axially oriented CeO 2 and NiO films were fabricated on {1 0 0} <0 0 1> textured Ni substrate by the same method and used as templates. At a constant working pressure of 10 Torr, the deposition temperatures (660-800 °C) and oxygen flow rates (100-500 sccm) were changed to find the optimum deposition condition. The best (1 0 0) oriented YSZ film on MgO was obtained at 740 °C and O 2 flow rate of 300 sccm. For a YSZ buffer layer with this deposition condition on a CeO 2/Ni template, full width half maximum values of the in-plane ( ϕ-scan) and out-of-plane ( ω-scan) alignments were 10.6° and 9.8°, respectively. The SEM image of YSZ film on CeO 2/Ni showed surface morphologies without microcracks. The film deposition rate was about 100 nm/min.

  19. Observations of YBCO superconductors under a low-temperature scanning electron microscope

    SciTech Connect

    Vyas, A.; Lam, C. C.; Li, S. H.; Lam, H. S.; Fung, P. C. W.

    1999-09-01

    Microscopic analyses have been performed on YBCO superconductors with Ca-doping and Gd-doping as a function of temperature by employing a low-temperature scanning electron microscope (LTSEM). On lowering temperature of the sample from 300 K to 90 K, the brightness of the SEM image changes due to the change in resistance of the sample. For the underdoped cuprates Y{sub 1-x}Ca{sub x}Ba{sub 2}Cu{sub 3}O{sub 7-{delta}}, with x=0.2, the pseudo gap in the normal state is opened at a temperature T* which far below the critical temperature T{sub c} of the superconductor. The opening of the pseudo gap has directly been observed under LTSEM (temperature fluctuating in the range of {+-}5 K). At temperature T* the formation of quasi-particles takes place, thus a sudden brightness change in the SEM image is observed. The results of these measurements are compared with the four-point probe measurements. It is proved that the data of these two measurements are quite in agreement with each other.

  20. High critical current YBCO thick films by TFA-MOD process

    NASA Astrophysics Data System (ADS)

    Tokunaga, Yoshitaka; Fuji, Hiroshi; Teranishi, Ryo; Shibata, Junko; Asada, Sigenobu; Honjo, Tetsuji; Izumi, Teruo; Shiohara, Yuh; Iijima, Yasuhiro; Saitoh, Takashi

    2003-10-01

    As a method of the fabrication processes of YBa 2Cu 3O 7- x (YBCO), the metalorganic deposition (MOD) process using metal trifluoroacetete (TFA) is considered to be a strong candidate due to its low cost fabrication process for coated conductors with high Jc. In our previous work, a triple coated film with 1 μm in thickness was fabricated on a CeO 2/IBAD-YSZ layer buffered Hastelloy substrate by optimizing the condition of heat treatments such as P H 2O in the multi-coating method [Physica C 378-381 (2002) 1013]. The Jc value of 1.6 MA/cm 2 (77 K in self-field) in this film patterned 100 μm width and the Ic* value of 153 A/cm-width at 77 K in self-field were achieved. In order to obtain a thicker film with high overall Ic* for 1 cm width, the influence of the heat treatment conditions of P H 2O , P O 2, and the temperature in the MOD process was investigated. Subsequently, a 5 times coated film was obtained on a CeO 2/IBAD-Zr 2Gd 2O 7 layer buffered Hastelloy substrate by optimizing the conditions of heating and dip coating. As a result, the overall transport Ic value was improved to 210 A and Jc value of 1.53 MA/cm 2 was obtained (77 K in self-field).

  1. The effect of disorder on the critical points in the vortex phase diagram of YBCO

    SciTech Connect

    Crabtree, G. W.; Kwok, W. K.; Paulius, L. M.; Petrean, A. M.; Olsson, R. J.; Karapetrov, G.; Tobos, V.; Moulton, W. G.

    2000-01-19

    The effect of line disorder induced by heavy ion irradiation and of point disorder induced by proton and electron irradiation on the upper and lower critical points in the vortex phase diagram of YBCO is presented. The authors find that dilute line disorder induces a Bose glass transition at low fields which is replaced at the lower critical point by first order melting at higher fields. Strong pinning point defects raise the lower critical point, while weak pinning point defects have little or no effect on the lower critical point. The upper critical point is lowered by point disorder, but raised by line disorder. First order melting is suppressed by point disorder in two ways, by lowering of the upper critical point only for weak point pins, or by merging of the upper and lower critical points for strong point pins. The differing responses of the upper and lower critical points to line and point disorder can be understood in a picture of transverse and longitudinal spatial fluctuations.

  2. Superconducting YBCO thin film on multicrystalline Ag film evaporated on MgO substrate

    NASA Astrophysics Data System (ADS)

    Azoulay, Jacob; Verdyan, Armen; Lapsker, Igor

    Superconducting YBa 2Cu 3O 7-δ films were grown by resistive evaporation on multicrystalline silver film which was evaporated on MgO substrate. A simple inexpensive vacuum system equipped with resistively heated boat was used for the whole process. Silver film was first evaporated on MgO substrate kept at 400°C during the evaporation after which with no further annealing a precursor mixture of yttrium small grains and Cu and BaF2 in powder form weighed in the atomic proportion to yield stoichiometric YBa 2Cu 3O 7 was evaporated. The films thus obtained were annealed at 740°C under low oxygen partial pressure of about 1Pa for 30 minutes to form the superconducting phase. X-ray diffraction and scanning electron microscopy techniques were used for texture and surface analysis. Electrical properties were determined using a standard dc four-probe for electrical measurements. The physical and electrical properties of the YBCO films are discussed in light of the fact that X-ray diffraction measurements done on the silver film have revealed a multicrystalline structure

  3. Microstructural evolution in multiseeded YBCO bulk samples grown by the TSMG process

    NASA Astrophysics Data System (ADS)

    Goodfellow, A.; Shi, Y.-H.; Durrell, J. H.; Dennis, A. R.; Cardwell, D. A.; Grovenor, C. R. M.; Speller, S. C.

    2016-11-01

    Superconducting single-grain YBCO bulk samples with the ability to trap high magnetic fields can be grown using the top-seeded melt-growth process. Multiseeding techniques have the potential to enable larger diameter bulks to be grown, but the performance of these materials is not yet comparable to the single-seeded bulks. Here we carry out detailed three-dimensional microstructural characterisation on a multiseeded sample grown with the seeds aligned in the 0°-0° geometry using high resolution microanalysis techniques. Chemical and structural variations have been correlated with the trapped field distribution in three separate slices of the sample. The top slice of the sample shows four peaks in trapped field, indicating that the current flows in four separate loops rather than in one large loop within the sample. This has been explained by the build-up in insulating Y-211 particles where the growth fronts from the two seeds meet, forming a barrier to current flow, as well as the low Y-211 content (and hence low J c) of the large c-axis growth sector.

  4. Pseudogap signatures measured in the Fermi surface of underdoped YBCO by quantum oscillations

    NASA Astrophysics Data System (ADS)

    Sebastian, Suchitra E.

    2013-03-01

    Solving the riddle of the pseudogap state in underdoped high temperature superconductors is critical to the understanding of the origin of high temperature superconductivity. Quantum oscillations performed on single crystals of the family of underdoped YBCO cuprates reveal small Fermi surface pockets in the normal state accessed at low temperatures and high magnetic fields. It has been widely thought, however, that high magnetic fields cause this state to be significantly different from the mysterious pseudogap state measured at high temperatures and low magnetic fields. In this talk I will present a quantum oscillation study of underdoped YBa2Cu3O6+x up to magnetic fields of 100 T that reveals a dimensional collapse of the Fermi surface due to a drastic reduction in c-axis hopping, identical to the pseudogap signature measured in the low magnetic field regime. We therefore conclude that the fundamental properties of the pseudogap are encoded in the Fermi surface, an understanding of which is critical to uncovering the origin of the pseudogap in high temperature superconductors. Possible mechanisms are discussed to explain the origin of the Fermi surface in underdoped YBa2Cu3O6+x. This work was performed in collaboration with G. Lonzarich (University of Cambridge), N. Harrison, M. Altarawneh, F. Balakirev (Los Alamos National Laboratory), and R. Liang, W. Hardy, D. Bonn (University of British Columbia)

  5. Ceramic Laser Materials

    SciTech Connect

    Soules, T F; Clapsaddle, B J; Landingham, R L; Schaffers, K I

    2005-02-15

    Transparent ceramic materials have several major advantages over single crystals in laser applications, not the least of which is the ability to make large aperture parts in a robust manufacturing process. After more than a decade of working on making transparent YAG:Nd, Japanese workers have recently succeeded in demonstrating samples that performed as laser gain media as well as their single crystal counterparts. Since then several laser materials have been made and evaluated. For these reasons, developing ceramic laser materials is the most exciting and futuristic materials topic in today's major solid-state laser conferences. We have established a good working relationship with Konoshima Ltd., the Japanese producer of the best ceramic laser materials, and have procured and evaluated slabs designed by us for use in our high-powered SSHCL. Our measurements indicate that these materials will work in the SSHCL, and we have nearly completed retrofitting the SSHCL with four of the largest transparent ceramic YAG:Nd slabs in existence. We have also begun our own effort to make this material and have produced samples with various degrees of transparency/translucency. We are in the process of carrying out an extensive design-of-experiments to establish the significant process variables for making transparent YAG. Finally because transparent ceramics afford much greater flexibility in the design of lasers, we have been exploring the potential for much larger apertures, new materials, for example for the Mercury laser, other designs for SSHL, such as, edge pumping designs, slabs with built in ASE suppression, etc. This work has just beginning.

  6. Ceramic tubesheet design analysis

    SciTech Connect

    Mallett, R.H.; Swindeman, R.W.

    1996-06-01

    A transport combustor is being commissioned at the Southern Services facility in Wilsonville, Alabama to provide a gaseous product for the assessment of hot-gas filtering systems. One of the barrier filters incorporates a ceramic tubesheet to support candle filters. The ceramic tubesheet, designed and manufactured by Industrial Filter and Pump Manufacturing Company (EF&PM), is unique and offers distinct advantages over metallic systems in terms of density, resistance to corrosion, and resistance to creep at operating temperatures above 815{degrees}C (1500{degrees}F). Nevertheless, the operational requirements of the ceramic tubesheet are severe. The tubesheet is almost 1.5 m in (55 in.) in diameter, has many penetrations, and must support the weight of the ceramic filters, coal ash accumulation, and a pressure drop (one atmosphere). Further, thermal stresses related to steady state and transient conditions will occur. To gain a better understanding of the structural performance limitations, a contract was placed with Mallett Technology, Inc. to perform a thermal and structural analysis of the tubesheet design. The design analysis specification and a preliminary design analysis were completed in the early part of 1995. The analyses indicated that modifications to the design were necessary to reduce thermal stress, and it was necessary to complete the redesign before the final thermal/mechanical analysis could be undertaken. The preliminary analysis identified the need to confirm that the physical and mechanical properties data used in the design were representative of the material in the tubesheet. Subsequently, few exploratory tests were performed at ORNL to evaluate the ceramic structural material.

  7. Ceramic oxide powders and the formation thereof

    DOEpatents

    Katz, J.L.; Chenghung Hung.

    1993-12-07

    Ceramic oxide powders and a method for their preparation. Ceramic oxide powders are obtained using a flame process whereby two or more precursors of ceramic oxides are introduced into a counterflow diffusion flame burner wherein said precursors are converted into ceramic oxide powders. The morphology, particle size, and crystalline form of the ceramic oxide powders are determined by process conditions. 14 figures.

  8. Ceramic oxide powders and the formation thereof

    DOEpatents

    Katz, Joseph L.; Hung, Cheng-Hung

    1993-01-01

    Ceramic oxide powders and a method for their preparation. Ceramic oxide powders are obtained using a flame process whereby two or more precursors of ceramic oxides are introduced into a counterflow diffusion flame burner wherein said precursors are converted into ceramic oxide powders. The morphology, particle size, and crystalline form of the ceramic oxide powders are determined by process conditions.

  9. Hydrogen defects in α-Al2O3 and water weakening of sapphire and alumina ceramics between 600°C and 1000°C: II. Mechanical properties

    USGS Publications Warehouse

    Castaing, J.; Kronenberg, A.K.; Kirby, S.H.; Mitchell, T.E.

    2000-01-01

    Hydrogen impurities in alumina have been introduced by hydrothermal annealing (see part I). In this paper, we report on reductions in the flow strength of α-Al2O3 single crystals and polycrystals associated with hydrogen incorporation. Prior to deformation, α-Al2O3 single crystal and ceramic specimens were annealed in the presence of supercritical water at 850° or 900°C, under 1500 MPa pressure. Sapphire and alumina ceramics were plastically deformed between 600° and 1000°C under 1500 MPa pressure, by the addition of a uniaxial stress. Flow stresses are reduced by a factor of two, due to the presence of water, for sapphire and large grain (30–50 μm) polycrystals, as a result of enhanced dislocation mobility. Flow stresses of fine-grained (3–5 μm) polycrystals are reduced by water by a factor of six. This large reduction in strength is attributed to a change in mechanism from dislocation glide under dry conditions to grain boundary sliding under hydrothermal conditions.

  10. Comparative characterization of a novel cad-cam polymer-infiltrated-ceramic-network

    PubMed Central

    Pascual, Agustín; Camps, Isabel; Grau-Benitez, María

    2015-01-01

    Background The field of dental ceramics for CAD-CAM is enriched with a new innovative material composition having a porous three-dimensional structure of feldspathic ceramic infiltrated with acrylic resins.The aim of this study is to determine the mechanical properties of Polymer-Infiltrated-Ceramic-Network (PICN) and compare its performance with other ceramics and a nano-ceramic resin available for CAD-CAM systems. Material and Methods In this study a total of five different materials for CAD-CAM were investigated. A polymer-infiltrated ceramic (Vita Enamic), a nano-ceramic resin (Lava Ultimate), a feldspathic ceramic (Mark II), a lithium disilicate ceramic (IPS-e max CAD) and finally a Leucite based ceramic (Empress - CAD). From CAD-CAM blocks, 120 bars (30 for each material cited above) were cut to measure the flexural strength with a three-point-bending test. Strain at failure, fracture stress and Weibull modulus was calculated. Vickers hardness of each material was also measured. Results IPS-EMAX presents mechanical properties significantly better from the other materials studied. Its strain at failure, flexural strength and hardness exhibited significantly higher values in comparison with the others. VITA ENAMIC and LAVA ULTIMATE stand out as the next most resistant materials. Conclusions The flexural strength, elastic modulus similar to a tooth as well as having less hardness than ceramics make PICN materials an option to consider as a restorative material. Key words:Ceramic infiltrated with resin, CAD-CAM, Weibull modulus, flexural strength, micro hardness. PMID:26535096

  11. Integrally cored ceramic investment casting mold fabricated by ceramic stereolithography

    NASA Astrophysics Data System (ADS)

    Bae, Chang-Jun

    Superalloy airfoils are produced by investment casting (IC), which uses ceramic cores and wax patterns with ceramic shell molds. Hollow cored superalloy airfoils in a gas turbine engine are an example of complex IC parts. The complex internal hollow cavities of the airfoil are designed to conduct cooling air through one or more passageways. These complex internal passageways have been fabricated by a lost wax process requiring several processing steps; core preparation, injection molding for wax pattern, and dipping process for ceramic shell molds. Several steps generate problems such as high cost and decreased accuracy of the ceramic mold. For example, costly tooling and production delay are required to produce mold dies for complex cores and wax patterns used in injection molding, resulting in a big obstacle for prototypes and smaller production runs. Rather than using separate cores, patterns, and shell molds, it would be advantageous to directly produce a mold that has the casting cavity and the ceramic core by one process. Ceramic stereolithography (CerSLA) can be used to directly fabricate the integrally cored ceramic casting mold (ICCM). CerSLA builds ceramic green objects from CAD files from many thin liquid layers of powder in monomer, which are solidified by polymerization with a UV laser, thereby "writing" the design for each slice. This dissertation addresses the integrally cored casting ceramic mold (ICCM), the ceramic core with a ceramic mold shell in a single patternless construction, fabricated by ceramic stereolithography (CerSLA). CerSLA is considered as an alternative method to replace lost wax processes, for small production runs or designs too complex for conventional cores and patterns. The main topic is the development of methods to successfully fabricate an ICCM by CerSLA from refractory silica, as well as related issues. The related issues are the segregation of coarse fused silica powders in a layer, the degree of segregation parameter to

  12. Ceramic Stereolithography: Additive Manufacturing for Ceramics by Photopolymerization

    NASA Astrophysics Data System (ADS)

    Halloran, John W.

    2016-07-01

    Ceramic stereolithography and related additive manufacturing methods involving photopolymerization of ceramic powder suspensions are reviewed in terms of the capabilities of current devices. The practical fundamentals of the cure depth, cure width, and cure profile are related to the optical properties of the monomer, ceramic, and photo-active components. Postpolymerization steps, including harvesting and cleaning the objects, binder burnout, and sintering, are discussed and compared with conventional methods. The prospects for practical manufacturing are discussed.

  13. Grain boundaries in ceramics and ceramic-metal interfaces

    SciTech Connect

    Clarke, D.R.; Wolf, D.

    1986-01-01

    Three interfaces exist: the crystal-crystal grain boundary in very pure single-phase ceramics, the crystal-glass-crystal grain boundary in most single-phase and polyphase ceramics, and the ceramic-metal interface. It is needed to correlate their structure and adhesion/failure. Methods for studying the bonding, interfacial structure, and fracture and adhesion are discussed, and recommendations are given. 42 refs. (DLC)

  14. Seal between metal and ceramic conduits

    DOEpatents

    Underwood, Richard Paul; Tentarelli, Stephen Clyde

    2015-02-03

    A seal between a ceramic conduit and a metal conduit of an ion transport membrane device consisting of a sealing surface of ceramic conduit, a sealing surface of ceramic conduit, a single gasket body, and a single compliant interlayer.

  15. Ceramic hot-gas filter

    DOEpatents

    Connolly, Elizabeth Sokolinski; Forsythe, George Daniel; Domanski, Daniel Matthew; Chambers, Jeffrey Allen; Rajendran, Govindasamy Paramasivam

    1999-01-01

    A ceramic hot-gas candle filter having a porous support of filament-wound oxide ceramic yarn at least partially surrounded by a porous refractory oxide ceramic matrix, and a membrane layer on at least one surface thereof. The membrane layer may be on the outer surface, the inner surface, or both the outer and inner surface of the porous support. The membrane layer may be formed of an ordered arrangement of circularly wound, continuous filament oxide ceramic yarn, a ceramic filler material which is less permeable than the filament-wound support structure, or some combination of continuous filament and filler material. A particularly effective membrane layer features circularly wound filament with gaps intentionally placed between adjacent windings, and a filler material of ceramic particulates uniformly distributed throughout the gap region. The filter can withstand thermal cycling during backpulse cleaning and is resistant to chemical degradation at high temperatures.

  16. Ceramic hot-gas filter

    DOEpatents

    Connolly, E.S.; Forsythe, G.D.; Domanski, D.M.; Chambers, J.A.; Rajendran, G.P.

    1999-05-11

    A ceramic hot-gas candle filter is described having a porous support of filament-wound oxide ceramic yarn at least partially surrounded by a porous refractory oxide ceramic matrix, and a membrane layer on at least one surface thereof. The membrane layer may be on the outer surface, the inner surface, or both the outer and inner surface of the porous support. The membrane layer may be formed of an ordered arrangement of circularly wound, continuous filament oxide ceramic yarn, a ceramic filler material which is less permeable than the filament-wound support structure, or some combination of continuous filament and filler material. A particularly effective membrane layer features circularly wound filament with gaps intentionally placed between adjacent windings, and a filler material of ceramic particulates uniformly distributed throughout the gap region. The filter can withstand thermal cycling during back pulse cleaning and is resistant to chemical degradation at high temperatures.

  17. In Situ deposition of YBCO high-T(sub c) superconducting thin films by MOCVD and PE-MOCVD

    NASA Technical Reports Server (NTRS)

    Zhao, J.; Noh, D. W.; Chern, C.; Li, Y. Q.; Norris, P.; Gallois, B.; Kear, B.

    1990-01-01

    Metalorganic Chemical Vapor Deposition (MOCVD) offers the advantages of a high degree of compositional control, adaptability for large scale production, and the potential for low temperature fabrication. The capability of operating at high oxygen partial pressure is particularly suitable for in situ formation of high temperature superconducting (HTSC) films. Yttrium barium copper oxide (YBCO) thin films having a sharp zero-resistance transition with T( sub c) greater than 90 K and Jc approx. 10 to the 4th power A on YSZ have been prepared, in situ, at a substrate temperature of about 800 C. Moreover, the ability to form oxide films at low temperature is very desirable for device applications of HTSC materials. Such a process would permit the deposition of high quality HTSC films with a smooth surface on a variety of substrates. Highly c-axis oriented, dense, scratch resistant, superconducting YBCO thin films with mirror-like surfaces have been prepared, in situ, at a reduced substrate temperature as low as 570 C by a remote microwave-plasma enhanced metalorganic chemical vapor deposition (PE-MOCVD) process. Nitrous oxide was used as a reactant gas to generate active oxidizing species. This process, for the first time, allows the formation of YBCO thin films with the orthorhombic superconducting phase in the as-deposited state. The as-deposited films grown by PE-MOCVD show attainment of zero resistance at 72 K with a transition width of about 5 K. MOCVD was carried out in a commercial production scale reactor with the capability of uniform deposition over 100 sq cm per growth run. Preliminary results indicate that PE-MOCVD is a very attractive thin film deposition process for superconducting device technology.

  18. In-situ deposition of YBCO high-Tc superconducting thin films by MOCVD and PE-MOCVD

    NASA Technical Reports Server (NTRS)

    Zhao, J.; Noh, D. W.; Chern, C.; Li, Y. Q.; Norris, P. E.; Kear, B.; Gallois, B.

    1991-01-01

    Metal-Organic Chemical Vapor Deposition (MOCVD) offers the advantages of a high degree of compositional control, adaptability for large scale production, and the potential for low temperature fabrication. The capability of operating at high oxygen partial pressure is particularly suitable for in situ formation of high temperature superconducting (HTSC) films. Yttrium barium copper oxide (YBCO) thin films having a sharp zero-resistance transition with T(sub c) greater than 90 K and J(sub c) of approximately 10(exp 4) A on YSZ have been prepared, in situ, at a substrate temperature of about 800 C. Moreover, the ability to form oxide films at low temperature is very desirable for device applications of HTSC materials. Such a process would permit the deposition of high quality HTSC films with a smooth surface on a variety of substrates. Highly c-axis oriented, dense, scratch resistant, superconducting YBCO thin films with mirror-like surfaces have been prepared, in situ, at a reduced substrate temperature as low as 570 C by a remote microwave-plasma enhanced metal-organic chemical vapor deposition (PE-MOCVD) process. Nitrous oxide was used as a reactant gas to generate active oxidizing species. This process, for the first time, allows the formation of YBCO thin films with the orthorhombic superconducting phase in the as-deposited state. The as-deposited films grown by PE-MOCVD show attainment of zero resistance at 72 K with a transition width of about 5 K. MOCVD was carried out in a commercial production scale reactor with the capability of uniform deposition over 100 sq cm per growth run. Preliminary results indicate that PE-MOCVD is a very attractive thin film deposition process for superconducting device technology.

  19. General approach for the determination of the magneto-angular dependence of the critical current of YBCO coated conductors

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Zhong, Z.; Ruiz, H. S.; Geng, J.; Coombs, T. A.

    2017-02-01

    The physical understanding and numerical modelling of superconducting devices which exploit the high performance of second generation high temperature superconducting tapes (2G-HTS), is commonly hindered by the lack of accurate functions which allow the consideration of the in-field dependence of the critical current. This is true regardless of the manufacturer of the superconducting tape. In this paper, we present a general approach for determining a unified function I c(B, θ), ultimately capable of describing the magneto-angular dependence of the in-field critical current of commercial 2G-HTS tapes in the Lorentz configuration. Five widely different superconducting tapes, provided by three different manufacturers, have been tested in a liquid nitrogen bath and external magnetic fields of up to 400 mT. The critical current was recorded at 90 different orientations of the magnetic field ranging from θ = 0°, i.e., with B aligned with the crystallographic ab-planes of the YBCO layer, towards ±90°, i.e., with B perpendicular to the wider surfaces of the 2G-HTS tape. The whole set of experimental data has been analysed using a novel multi-objective model capable of predicting a sole function I c(B, θ). This allows an accurate validation of the experimental data regardless of the fabrication differences and widths of the superconducting tapes. It is shown that, in spite of the wide set of differences between the fabrication and composition of the considered tapes, at liquid nitrogen temperature the magneto-angular dependence of the in-field critical current of YBCO-based 2G-HTS tapes, can be described by a universal function I c(f(B), θ), with a power law field dependence dominated by the Kim’s factor B/B 0, and an angular dependence moderated by the electron mass anisotropy ratio of the YBCO layer.

  20. Effect of surface modification of CeO2 buffer layers on Jc and defect microstructures of large-area YBCO thin films

    NASA Astrophysics Data System (ADS)

    Develos-Bagarinao, K.; Yamasaki, H.; Nakagawa, Y.

    2006-08-01

    High-quality CeO2 buffer layers are requisite for the successful growth of YBCO thin films with excellent properties on sapphire substrates. In this study, we evaluated the effect of surface modification of the CeO2 layers on the properties of the YBCO thin films prepared by large-area pulsed laser deposition (PLD), in particular the critical current density Jc and defect microstructure. High-temperature annealing (1050 °C) has been found to significantly smoothen the very rough and granular surfaces of the as-grown CeO2 layers (surface roughness rms~5-10 nm) to atomic flatness (rms~0.5 nm). However, a rather unique characteristic of the CeO2 layers deposited by large-area PLD is the development of pores when subjected to prolonged high-temperature annealing. For very short annealing periods (10-20 min), the surface morphology becomes atomically flat, along with the appearance of a high density of 'nanopores' that are ~40-100 nm in diameter and ~3-5 nm in depth. Extending the annealing period to 60 min or more results in the development of a surface subtended with enlarged pores ~0.2-0.5 µm in diameter. Compared with the YBCO thin films deposited on as-grown CeO2, YBCO thin films on annealed CeO2 exhibited better homogeneity of Jc and better crystalline texture. Among the YBCO thin films deposited on annealed CeO2, higher self-field and in-field Jc was obtained for YBCO thin films deposited on CeO2 with smooth surfaces but interspersed with nanopores. Investigation of the defect microstructure via the etch pit method in conjunction with atomic force microscopy (AFM) of the YBCO thin films revealed a high density of linear defects in the form of screw and edge dislocations, which correlated well with a high density of nanopores on annealed CeO2. Transmission electron microscopy (TEM) further confirmed the presence of threading dislocations clearly emanating from the nanopore sites. Angular dependence of Jc revealed enhanced flux pinning for YBCO thin films

  1. Testing Ceramics for Diesel Engines

    NASA Technical Reports Server (NTRS)

    Schneider, H. W.

    1985-01-01

    Adaptation of diesel engine allows prestressed ceramic materials evaluated under realistic pressure, temperature, and stress without introducing extraneous stress. Ceramic specimen part of prechamber of research engine. Specimen held in place by clamp, introduces required axial compressive stress. Specimen -- cylindrical shell -- surrounded by chamber vented or pressurized to introduce requisite radial stress in ceramic. Pressure chamber also serves as safety shield in case speimen disintegrates. Materials under consideration as cylinder liners for diesel engines.

  2. Processing method for superconducting ceramics

    DOEpatents

    Bloom, Ira D.; Poeppel, Roger B.; Flandermeyer, Brian K.

    1993-01-01

    A process for preparing a superconducting ceramic and particularly YBa.sub.2 Cu.sub.3 O.sub.7-.delta., where .delta. is in the order of about 0.1-0.4, is carried out using a polymeric binder which decomposes below its ignition point to reduce carbon residue between the grains of the sintered ceramic and a nonhydroxylic organic solvent to limit the problems with water or certain alcohols on the ceramic composition.

  3. Processing method for superconducting ceramics

    DOEpatents

    Bloom, Ira D.; Poeppel, Roger B.; Flandermeyer, Brian K.

    1993-02-02

    A process for preparing a superconducting ceramic and particularly YBa.sub.2 Cu.sub.3 O.sub.7-.delta., where .delta. is in the order of about 0.1-0.4, is carried out using a polymeric binder which decomposes below its ignition point to reduce carbon residue between the grains of the sintered ceramic and a nonhydroxylic organic solvent to limit the problems with water or certain alcohols on the ceramic composition.

  4. Tailored Ceramics for Laser Applications

    SciTech Connect

    Hollingsworth, Joel

    2007-12-10

    Transparent ceramics match or exceed the performance of single-crystal materials in laser applications, with a more-robust fabrication process. Controlling the distribution of optical dopants in transparent ceramics would allow qualitative improvements in amplifier slab design by allowing gain and loss to be varied within the material. My work aims to achieve a controlled pattern or gradient of dopant prior to sintering, in order to produce tailored ceramics.

  5. Ceramic composite coating

    DOEpatents

    Wicks, G.G.

    1997-01-21

    A thin, room-temperature-curing, ceramic composite for coating and patching metal substrates comprises a sol gel silica glass matrix filled with finely ground particles or fibers, preferably alumina. The sol gel glass is made by adding ethanol to water to form a first mixture, then separately adding ethanol to tetraethyl orthosilicate to form a second mixture, then slowly adding the first to the second mixture to make a third mixture, and making a slurry by adding the finely ground particles or fibers to the third mixture. The composite can be applied by spraying, brushing or trowelling. If applied to patch fine cracks, densification of the ceramic composite may be obtained to enhance sealing by applying heat during curing.

  6. Ceramic composite coating

    DOEpatents

    Wicks, George G.

    1997-01-01

    A thin, room-temperature-curing, ceramic composite for coating and patching etal substrates comprises a sol gel silica glass matrix filled with finely ground particles or fibers, preferably alumina. The sol gel glass is made by adding ethanol to water to form a first mixture, then separately adding ethanol to tetraethyl orthosilicate to form a second mixture, then slowly adding the first to the second mixture to make a third mixture, and making a slurry by adding the finely ground particles or fibers to the third mixture. The composite can be applied by spraying, brushing or trowelling. If applied to patch fine cracks, densification of the ceramic composite may be obtained to enhance sealing by applying heat during curing.

  7. Ceramic Composite Thin Films

    NASA Technical Reports Server (NTRS)

    Ruoff, Rodney S. (Inventor); Stankovich, Sasha (Inventor); Dikin, Dmitriy A. (Inventor); Nguyen, SonBinh T. (Inventor)

    2013-01-01

    A ceramic composite thin film or layer includes individual graphene oxide and/or electrically conductive graphene sheets dispersed in a ceramic (e.g. silica) matrix. The thin film or layer can be electrically conductive film or layer depending the amount of graphene sheets present. The composite films or layers are transparent, chemically inert and compatible with both glass and hydrophilic SiOx/silicon substrates. The composite film or layer can be produced by making a suspension of graphene oxide sheet fragments, introducing a silica-precursor or silica to the suspension to form a sol, depositing the sol on a substrate as thin film or layer, at least partially reducing the graphene oxide sheets to conductive graphene sheets, and thermally consolidating the thin film or layer to form a silica matrix in which the graphene oxide and/or graphene sheets are dispersed.

  8. Ceramics for fusion applications

    SciTech Connect

    Clinard, F.W. Jr.

    1986-01-01

    Ceramics are required for a variety of uses in both near-term fusion devices and in commercial powerplants. These materials must retain adequate structural and electrical properties under conditions of neutron, particle, and ionizing irradiation; thermal and applied stresses; and physical and chemical sputtering. Ceramics such as Al/sub 2/O/sub 3/, MgAl/sub 2/O/sub 4/, BeO, Si/sub 3/N/sub 4/ and SiC are currently under study for fusion applications, and results to date show widely-varying response to the fusion environment. Materials can be identified today which will meet initial operating requirements, but improvements in physical properties are needed to achieve satisfactory lifetimes for critical applications.

  9. Ceramic fabrication R D

    SciTech Connect

    Not Available

    1990-01-01

    This project is separated into three tasks. The first task is a design and modeling effort to be carried out by MSE, Inc. The purpose of this task is to develop and analyze designs for various cohesive ceramic fabrication (CCF) components, including an MHD electrode for strategic defense initiative (SDI) applications and a high stress, low cost, reinforced ceramic component for armor applications. The MHD electrode design is substantially completed. A layered structure composed of molybdenum disilicide graded with quartz glass has been designed and analyzed using finite element methods. The design demonstrates the fabrication capabilities of the CCF process. The high stress, armor application component will be silicon carbide reinforced alumina in thick plates. 2 refs., 4 figs., 1 tab.

  10. Co-evaporated YBCO/doped-CeO 2/Ni-W coated conductors oxygen improved using a supersonic nozzle

    NASA Astrophysics Data System (ADS)

    Gilioli, E.; Baldini, M.; Bindi, M.; Bissoli, F.; Pattini, F.; Rampino, S.; Ginocchio, S.; Gauzzi, A.; Rocca, M.; Zannella, S.

    2007-10-01

    A novel process for the coated conductors (CC) deposition, characterized by a single CeO2 buffer layer architecture, and a new oxygenation device for the YBCO layer has been developed. In CC technology, usually the ceria layer thickness must be less than 100 nm to avoid the formation of cracks; in order to ensure an efficient barrier effect, complex and costly multi-buffer layers architectures must be grown. In this work, we describe the way to increase the thickness of crack-free single buffer layer.

  11. Challenges in Modeling the Degradation of Ceramic Waste Forms

    SciTech Connect

    Devanathan, Ramaswami; Gao, Fei; Sun, Xin

    2011-09-01

    We identify the state of the art, gaps in current understanding, and key research needs in the area of modeling the long-term degradation of ceramic waste forms for nuclear waste disposition. The directed purpose of this report is to define a roadmap for Waste IPSC needs to extend capabilities of waste degradation to ceramic waste forms, which overlaps with the needs of the subconsinuum scale of FMM interests. The key knowledge gaps are in the areas of (i) methodology for developing reliable interatomic potentials to model the complex atomic-level interactions in waste forms; (ii) characterization of water interactions at ceramic surfaces and interfaces; and (iii) extension of atomic-level insights to the long time and distance scales relevant to the problem of actinide and fission product immobilization.

  12. Microprobes aluminosilicate ceramic membranes

    DOEpatents

    Anderson, Marc A.; Sheng, Guangyao

    1993-01-01

    Methods have been developed to make mixed alumina-silicate and aluminosilicate particulate microporous ceramic membranes. One method involves the making of separate alumina and silica sols which are then mixed. Another method involves the creation of a combined sol with aluminosilicate particles. The resulting combined alumina and silica membranes have high surface area, a very small pore size, and a very good temperature stability.

  13. Miniature ceramic fuel cell

    DOEpatents

    Lessing, Paul A.; Zuppero, Anthony C.

    1997-06-24

    A miniature power source assembly capable of providing portable electricity is provided. A preferred embodiment of the power source assembly employing a fuel tank, fuel pump and control, air pump, heat management system, power chamber, power conditioning and power storage. The power chamber utilizes a ceramic fuel cell to produce the electricity. Incoming hydro carbon fuel is automatically reformed within the power chamber. Electrochemical combustion of hydrogen then produces electricity.

  14. Transformation Toughening of Ceramics

    DTIC Science & Technology

    1992-03-01

    TRANSFORMATION ZONE SHAPE EFFECTS IN CRACK SHIELDING IN CERIA-PARTIALLY STABILIZED ZIRCONIA (Ce-TZP). ALUMINA COMPOSITES to be published in J. Am. Ceram. Soc. 13 Cl...lS85HWejw TRANSFORMATION ZONE SHAPE EFFECTS ON CRACK SHIELDING IN CERIA-PARTIALLY-STABILIZED ZIRCONIA (Ce-TZP)- ALUMINA S..COMPOSITES Cheng-Sheng Yu...zones in Ce-TZP/Al203 composites, in which the transformation zone sizes were changed significantly by varying the sintering temperature to control

  15. Superplastic forging nitride ceramics

    DOEpatents

    Panda, Prakash C.; Seydel, Edgar R.; Raj, Rishi

    1988-03-22

    The invention relates to producing relatively flaw free silicon nitride ceramic shapes requiring little or no machining by superplastic forging This invention herein was made in part under Department of Energy Grant DE-AC01-84ER80167, creating certain rights in the United States Government. The invention was also made in part under New York State Science and Technology Grant SB1R 1985-10.

  16. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2001-12-01

    Conversion of natural gas to liquid fuels and chemicals is a major goal for the Nation as it enters the 21st Century. Technically robust and economically viable processes are needed to capture the value of the vast reserves of natural gas on Alaska's North Slope, and wean the Nation from dependence on foreign petroleum sources. Technologies that are emerging to fulfill this need are all based syngas as an intermediate. Syngas (a mixture of hydrogen and carbon monoxide) is a fundamental building block from which chemicals and fuels can be derived. Lower cost syngas translates directly into more cost-competitive fuels and chemicals. The currently practiced commercial technology for making syngas is either steam methane reforming (SMR) or a two-step process involving cryogenic oxygen separation followed by natural gas partial oxidation (POX). These high-energy, capital-intensive processes do not always produce syngas at a cost that makes its derivatives competitive with current petroleum-based fuels and chemicals. This project has the following 6 main tasks: Task 1--Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints. Task 2--Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability. Task 3--Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres. Task 4--Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures. Task 5--Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability. Task 6--Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques.

  17. Transparent Spinel Ceramic

    DTIC Science & Technology

    2009-01-01

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

  18. Multifracture of ceramic composites

    SciTech Connect

    Weitsman, Y.J. ); Zhu, H. )

    1992-03-01

    This work presents a mechanistic model for the multifracture process of uniaxially reinforced fibrous ceramic composites under monotonically increasing tension parallel to the fiber direction. The model employs an energy criterion to account for the progression of matrix cracks, bridged by intact fibers, and Weibull failure statistics to relate the failure of the fibers. Consideration is given to the interactions between the foregoing failure processes as well as to the effects of various material parameters on the response of the composite.

  19. Joined ceramic product

    DOEpatents

    Henager, Jr., Charles W [Kennewick, WA; Brimhall, John L [West Richland, WA

    2001-08-21

    According to the present invention, a joined product is at least two ceramic parts, specifically bi-element carbide parts with a bond joint therebetween, wherein the bond joint has a metal silicon phase. The bi-element carbide refers to compounds of MC, M.sub.2 C, M.sub.4 C and combinations thereof, where M is a first element and C is carbon. The metal silicon phase may be a metal silicon carbide ternary phase, or a metal silicide.

  20. Transformation Toughening of Ceramics

    DTIC Science & Technology

    1988-12-01

    International Science Center SC5444.FR 1. INTRODUCTION Zirconia -containing ceramics can be toughened dramatically by the marten- sitic tetragonal -to-monoclinic...cm- 1) coincide with peaks of the monoclinic phase (Fig. 3(c)), but the remaining nine do not belong to any of the tetragonal , monoclinic or cubic ... tetragonal precipitates and the remainder cubic matrix. After cooling, there was no change in the intensities of the monoclinic peaks (e.g. (G1T)and (111

  1. Aspects of passive magnetic levitation based on high-T(sub c) superconducting YBCO thin films

    NASA Technical Reports Server (NTRS)

    Schoenhuber, P.; Moon, F. C.

    1995-01-01

    Passive magnetic levitation systems reported in the past were mostly confined to bulk superconducting materials. Here we present fundamental studies on magnetic levitation employing cylindrical permanent magnets floating above high-T(sub c) superconducting YBCO thin films (thickness about 0.3 mu m). Experiments included free floating rotating magnets as well as well-established flexible beam methods. By means of the latter, we investigated levitation and drag force hysteresis as well as magnetic stiffness properties of the superconductor-magnet arrangement. In the case of vertical motion of the magnet, characteristic high symmetry of repulsive (approaching) and attractive (withdrawing) branches of the pronounced force-displacement hysteresis could be detected. Achievable force levels were low as expected but sufficient for levitation of permanent magnets. With regard to magnetic stiffness, thin films proved to show stiffness-force ratios about one order of magnitude higher than bulk materials. Phenomenological models support the measurements. Regarding the magnetic hysteresis of the superconductor, the Irie-Yamafuji model was used for solving the equation of force balance in cylindrical coordinates allowing for a macroscopic description of the superconductor magnetization. This procedure provided good agreement with experimental levitation force and stiffness data during vertical motion. For the case of (lateral) drag force basic qualitative characteristics could be recovered, too. It is shown that models, based on simple asymmetric magnetization of the superconductor, describe well asymptotic transition of drag forces after the change of the magnet motion direction. Virgin curves (starting from equilibrium, i.e. symmetric magnetization) are approximated by a linear approach already reported in literature only. This paper shows that basic properties of superconducting thin films allow for their application to magnetic levitation or - without need of levitation

  2. Magnetism in EuBCO and YBCO vortex states near and below Tc

    NASA Astrophysics Data System (ADS)

    Schwartz, R.; Browne, M. C.; Boekema, C.

    2012-02-01

    By means of MaxEnt-μSR [1] analysis, we investigate transverse field μSR data [2] of EuBa2Cu3O7-δgEuBCO; Tc = 93 K). Our focus is on a temperature interval near Tc to search for precursor effects, [3] and for predicted [4a] pseudogap loop currents above and below Tc, already observed [4b] above Tc for GdBCO. Further, we continue to study the field-direction dependence of the predicted [5a] and observed [5b] antiferromagnetism (AF) below 0.5Tc for the vortex states in c-axis-oriented YBCO. This AF in and near the vortex cores is likely three-dimensional. In sum, magnetic roots of cuprate superconductivity are well plausible. Research is supported by LANL-DOE, REU-NSF and AFC. [4pt] [1] C Boekema and MC Browne, AIP Conf Proc #1073 (2008) 260.[0pt] [2] DW Cooke et al, Phys Rev B 39 (1989) 2748.[0pt] [3] B Aguilar, C Boekema et al, Bull Am Phys Soc 37 (1992).[0pt] [4a] CM Varma, Phys Rev Lett 83 (1999) 3538.[0pt] [4b] T Songatikamas et al, J Supercond & Novel Magn 23 (2010) 793.[0pt] [5a] S-C Zhang, Science 275 (1997) 1089; H-D Chen et al, Phys Rev B70 (2004) 024516.[0pt] [5b] C. Boekema et al, J Phys Conf Series, 150 (2009) 052022. http://jpcs.iop.org/LT25

  3. Temperature dependence of the dielectric function of laser deposited YBCO thin film at 3392nm

    SciTech Connect

    Walmsley, D.G.; Bade, T.; McCafferty, P.G.; Rea, C.; Dawson, P.; Wallace, R.J.; Bowman, R.M.

    1996-12-31

    The authors have excited surface plasmons in an YBCO thin film at different temperatures using attenuated total reflection of light. The 300nm thick c-axis film was fabricated using pulsed laser deposition onto an MgO (100) substrate with 248nm KrF excimer radiation. Critical temperature of the film was 89.6K and its roughness, as shown by atomic force microscopy, 20nm rms, without droplets over areas of 10 {micro}m x 10{micro}m. The sample was mounted in Otto geometry on a cooled stage which allowed the temperature to be varied between 300K and 70K. An infrared HeNe laser at 3,392nm was used to excite the surface plasmons. The dielectric function of the film was determined between room temperature and 80K. The imaginary part of the dielectric function decreased substantially with reduction in temperature. Results obtained were: {var_epsilon}{sub r} = {minus}24.1 + 0.0013T and {var_epsilon}{sub i} = 7.7 + 0.067T where T is the temperature in kelvin. The ratio {var_epsilon}{sub i}{sup 300}/{var_epsilon}{sub i}{sup 80} at 2.13 is less than the resistance ratio R{sup 300}/R{sup 80} at 2.81. An explanation is offered in terms of two temperature independent mechanisms operative at optical frequencies: enhanced Rayleigh scattering of surface plasmons at grain boundaries and intraband/interband transitions. The real part of the dielectric function, {var_epsilon}{sub r}, was found to be only slightly temperature dependent. It was, however, highly sample dependent when comparison was made with the results of other films, a feature attributed to surface and grain boundary contamination.

  4. Aspects of passive magnetic levitation based on high-T{sub c} superconducting YBCO thin films

    SciTech Connect

    Schoenhuber, P.; Moon, F.C.

    1995-04-01

    Passive magnetic levitation systems reported in the past were mostly confined to bulk superconducting materials. Here the authors present fundamental studies on magnetic levitation employing cylindrical permanent magnets floating above high-T{sub c} superconducting YBCO thin films (thickness about 0.3 mu m). Experiments included free floating rotating magnets as well as well-established flexible beam methods. By means of the latter, the authors investigated levitation and drag force hysteresis as well as magnetic stiffness properties of the superconductor-magnet arrangement. In the case of vertical motion of the magnet, characteristic high symmetry of repulsive (approaching) and attractive (withdrawing) branches of the pronounced force-displacement hysteresis could be detected. Achievable force levels were low as expected but sufficient for levitation of permanent magnets. With regard to magnetic stiffness, thin films proved to show stiffness-force ratios about one order of magnitude higher than bulk materials. Phenomenological models support the measurements. Regarding the magnetic hysteresis of the superconductor, the Irie-Yamafuji model was used for solving the equation of force balance in cylindrical coordinates allowing for a macroscopic description of the superconductor magnetization. This procedure provided good agreement with experimental levitation force and stiffness data during vertical motion. For the case of (lateral) drag force basic qualitative characteristics could be recovered, too. It is shown that models, based on simple asymmetric magnetization of the superconductor, describe well asymptotic transition of drag forces after the change of the magnet motion direction. Virgin curves (starting from equilibrium, i.e. symmetric magnetization) are approximated by a linear approach already reported in literature only. This paper shows that basic properties of superconducting thin films allow for their application to magnetic levitation.

  5. Ceramic stationary gas turbine

    SciTech Connect

    Roode, M. van

    1995-10-01

    The performance of current industrial gas turbines is limited by the temperature and strength capabilities of the metallic structural materials in the engine hot section. Because of their superior high-temperature strength and durability, ceramics can be used as structural materials for hot section components (blades, nozzles, combustor liners) in innovative designs at increased turbine firing temperatures. The benefits include the ability to increase the turbine inlet temperature (TIT) to about 1200{degrees}C ({approx}2200{degrees}F) or more with uncooled ceramics. It has been projected that fully optimized stationary gas turbines would have a {approx}20 percent gain in thermal efficiency and {approx}40 percent gain in output power in simple cycle compared to all metal-engines with air-cooled components. Annual fuel savings in cogeneration in the U.S. would be on the order of 0.2 Quad by 2010. Emissions reductions to under 10 ppmv NO{sub x} are also forecast. This paper describes the progress on a three-phase, 6-year program sponsored by the U.S. Department of Energy, Office of Industrial Technologies, to achieve significant performance improvements and emissions reductions in stationary gas turbines by replacing metallic hot section components with ceramic parts. Progress is being reported for the period September 1, 1994, through September 30, 1995.

  6. Ceramic stationary gas turbine

    SciTech Connect

    Roode, M. van

    1995-12-31

    The performance of current industrial gas turbines is limited by the temperature and strength capabilities of the metallic structural materials in the engine hot section. Because of their superior high-temperature strength and durability, ceramics can be used as structural materials for hot section components (blades, nozzles, combustor liners) in innovative designs at increased turbine firing temperatures. The benefits include the ability to increase the turbine inlet temperature (TIT) to about 1200{degrees}C ({approx}2200{degrees}F) or more with uncooled ceramics. It has been projected that fully optimized stationary gas turbines would have a {approx}20 percent gain in thermal efficiency and {approx}40 percent gain in output power in simple cycle compared to all metal-engines with air-cooled components. Annual fuel savings in cogeneration in the U.S. would be on the order of 0.2 Quad by 2010. Emissions reductions to under 10 ppmv NO{sub x} are also forecast. This paper describes the progress on a three-phase, 6-year program sponsored by the U.S. Department of Energy, Office of Industrial Technologies, to achieve significant performance improvements and emissions reductions in stationary gas turbines by replacing metallic hot section components with ceramic parts. Progress is being reported for the period September 1, 1994, through September 30, 1995.

  7. Anionic Conducting Oxide Ceramics: Microstructure - Property Relations of Bicuvox Ceramics.

    DTIC Science & Technology

    2007-11-02

    The bismuth vanadate composition, Bi4V2011, is the parent compound for a new family of oxygen ion conductors. The substitution of various metallic... bismuth vanadate ceramics. Phase-pure materials with densities above 95% of theoretical were obtained using standard ceramic processing approaches

  8. 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.

  9. 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.

  10. Life prediction methodology for ceramic components of advanced heat engines. Phase 1: Volume 2, Appendices

    SciTech Connect

    1995-03-01

    This volume presents the following appendices: ceramic test specimen drawings and schematics, mixed-mode and biaxial stress fracture of structural ceramics for advanced vehicular heat engines (U. Utah), mode I/mode II fracture toughness and tension/torsion fracture strength of NT154 Si nitride (Brown U.), summary of strength test results and fractography, fractography photographs, derivations of statistical models, Weibull strength plots for fast fracture test specimens, and size functions.

  11. Thickness-Dependent Properties of YBCO Films Grown on GZO/CLO-Buffered NiW Substrates

    NASA Astrophysics Data System (ADS)

    Malmivirta, M.; Huhtinen, H.; Zhao, Y.; Grivel, J.-C.; Paturi, P.

    2017-01-01

    To study the role of novel Gd_2Zr_2O_7/Ce_{0.9}La_{0.1}O_2 buffer layer structure on a biaxially textured NiW substrate, a set of YBa_2Cu_3O_{7-δ } (YBCO) films with different thicknesses were prepared by pulsed laser deposition (PLD). Interface imperfections as well as thickness-dependent structural properties were observed in the YBCO thin films. The structure is also reflected into the improved superconducting properties with the highest critical current densities in films with intermediate thicknesses. Therefore, it can be concluded that the existing buffer layers need more optimization before they can be successfully used for films with various thicknesses. This issue is linked to the extremely susceptible growth method of PLD when compared to the commonly used chemical deposition methods. Nevertheless, PLD-grown films can give a hint on what to concentrate to be able to further improve the buffer layer structures for future coated conductor technologies.

  12. Dependence of the structural, electrical and magnetic properties of the superconductive YBCO thin films on the deposition rate

    NASA Astrophysics Data System (ADS)

    Karci, A. B.; Tepe, M.; Sozeri, H.

    2009-03-01

    In this study, YBCO thin films on single crystal LaAlO3 (100) substrates have been grown using DC inverted cylindrical magnetron sputtering technique and the effect of the deposition rate on these films is investigated. Three different deposition rates are used to produce superconducting YBCO thin films with 150 nm of thickness on (100) LaAlO3 single crystal substrate at 780 0C. The samples are analyzed in detail by means of XRD, R-T, χ-T, M-H and AFM characterizations and also the critical current densities (Jc) are derived from the magnetic hysteresis curves using the modified Bean formula [1]. The critical current density at 50 K was found to be in the range of 3.107 A/m2 to 8. 107 A/m2 with a deposition rate between 2nm/min and 1.2nm/min. A correlation has been obtained so that as the film deposition rate increases, the surface smoothness and crystalline quality of the films significantly deteriorate, resulting in a significant decrease in Jc.

  13. Magnetization behavior and critical current density along the c-axis in melt-grown YBCO fiber crystal

    NASA Astrophysics Data System (ADS)

    Ishii, H.; Hara, T.; Hirano, S.; Figueredo, A. M.; Cima, M. J.

    1994-05-01

    The magnetic-hysteresis behavior of single-crystal YBCO fibers was investigated below 1 T and in the temperature range 40 to 88 K. The sample was prepared by the laser-heated floating zone method. The magnetization curves exhibited a fairly large asymmetry with respect to the field axis, especially at elevated temperatures. This behavior may be attributed to the surface Meissner current contribution. It was demonstrated for the temperature range examined that the magnetic hysteresis width, Δ M, versus external-field curves were well described by assuming that the critical current density in the c-axis direction Jcc obeys the critical-state model of the form Jc( B)= JcO[1+( B/ B0) n]-1. Then, in turn, the field dependence of the critical current density along the c-axis at field temperatures was deduced using parameters obtained by fitting the Δ M vs. field curves. It was shown that the critical current density in the direction of the c-axis in our sample was over 10 4 A/cm 2 at 77.3 K below 0.3 T. The field and temperature variations of Jcc were discussed in relation to the previous studies on some melt-processed YBCO.

  14. Method of forming ceramic bricks

    DOEpatents

    Poeppel, Roger B.; Claar, Terry D.; Silkowski, Peter

    1988-09-06

    A method for forming free standing ceramic bricks for use as tritium breeder material is disclosed. Aqueous solutions of sodium carbonate and potassium carbonate are mixed with an organic hydrocolloid dispersion and powdered lithium carbonate, spray dried, and ceramic bricks formed by molding in a die and firing.

  15. High Technology Ceramics in Japan

    DTIC Science & Technology

    1984-07-14

    ILtOjY CERAMICS IN JAPAN ,treas: among these are biotechnology . Oectronics. and new materials includins :eramics. The ceramics project is coordinated by...an emerging industr ,. During tuch an carly phase of industry development. product designs have yet to bc established. .nd several approaches to the

  16. Controlled Dynamic Fragmentation of Ceramics

    DTIC Science & Technology

    2009-12-14

    mechanism determining ballistic impact performance of ceramic armors as well as reliability of gun barrels. This program, which was sponsored by the...Research Office Fragmentation is a key damage mechanism determining ballistic impact performance of ceramic armors as well as reliability of gun ...the defect distributions that were considered (Weibull, Gauss and Uniform) fall on a single universal curve. Sdf

  17. Impact-Resistant Ceramic Coating

    NASA Technical Reports Server (NTRS)

    Wheeler, W. H.; Creedon, J. F.; Izu, Y. D.

    1986-01-01

    Refractory fibers more than double strength of coating. Impact strengths of ceramic coatings increase with increasing whisker content. Silicon carbide whiskers clearly produce largest increase, and improvement grows even more with high-temperature sintering. Coating also improves thermal and mechanical properties of electromagnetic components, mirrors, furnace linings, and ceramic parts of advanced internal-combustion engines.

  18. Method of forming ceramic bricks

    DOEpatents

    Poeppel, R.B.; Claar, T.D.; Silkowski, P.

    1987-04-22

    A method for forming free standing ceramic bricks for use as tritium breeder material is disclosed. Aqueous solutions of sodium carbonate and potassium carbonate are mixed with an organic hydrocolloid dispersion and powdered lithium carbonate, spray dried, and ceramic bricks formed by molding in a die and firing.

  19. Method of forming ceramic bricks

    DOEpatents

    Poeppel, Roger B.; Claar, Terry D.; Silkowski, Peter

    1988-01-01

    A method for forming free standing ceramic bricks for use as tritium breeder material is disclosed. Aqueous solutions of sodium carbonate and potassium carbonate are mixed with an organic hydrocolloid dispersion and powdered lithium carbonate, spray dried, and ceramic bricks formed by molding in a die and firing.

  20. Lightweight high performance ceramic material

    DOEpatents

    Nunn, Stephen D [Knoxville, TN

    2008-09-02

    A sintered ceramic composition includes at least 50 wt. % boron carbide and at least 0.01 wt. % of at least one element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy Ho, Er, Tm, Yb, and Lu, the sintered ceramic composition being characterized by a density of at least 90% of theoretical density.

  1. Ceramic applications in turbine engines

    NASA Technical Reports Server (NTRS)

    Byrd, J. A.; Janovicz, M. A.; Thrasher, S. R.

    1981-01-01

    Development testing activities on the 1900 F-configuration ceramic parts were completed, 2070 F-configuration ceramic component rig and engine testing was initiated, and the conceptual design for the 2265 F-configuration engine was identified. Fabrication of the 2070 F-configuration ceramic parts continued, along with burner rig development testing of the 2070 F-configuration metal combustor in preparation for 1132 C (2070 F) qualification test conditions. Shakedown testing of the hot engine simulator (HES) rig was also completed in preparation for testing of a spin rig-qualified ceramic-bladed rotor assembly at 1132 C (2070 F) test conditions. Concurrently, ceramics from new sources and alternate materials continued to be evaluated, and fabrication of 2070 F-configuration ceramic component from these new sources continued. Cold spin testing of the critical 2070 F-configuration blade continued in the spin test rig to qualify a set of ceramic blades at 117% engine speed for the gasifier turbine rotor. Rig testing of the ceramic-bladed gasifier turbine rotor assembly at 108% engine speed was also performed, which resulted in the failure of one blade. The new three-piece hot seal with the nickel oxide/calcium fluoride wearface composition was qualified in the regenerator rig and introduced to engine operation wiwth marginal success.

  2. Protective coating for ceramic materials

    NASA Technical Reports Server (NTRS)

    Kourtides, Demetrius A. (Inventor); Churchward, Rex A. (Inventor); Lowe, David M. (Inventor)

    1994-01-01

    A protective coating for ceramic materials such as those made of silicon carbide, aluminum oxide, zirconium oxide, aluminoborosilicate and silicon dioxide, and a thermal control structure comprising a ceramic material having coated thereon the protective coating. The protective coating contains, in admixture, silicon dioxide powder, colloidal silicon dioxide, water, and one or more emittance agents selected from silicon tetraboride, silicon hexaboride, silicon carbide, molybdenum disilicide, tungsten disilicide and zirconium diboride. In another aspect, the protective coating is coated on a flexible ceramic fabric which is the outer cover of a composite insulation. In yet another aspect, a metallic foil is bonded to the outer surface of a ceramic fabric outer cover of a composite insulation via the protective coating. A primary application of this invention is as a protective coating for ceramic materials used in a heat shield for space vehicles subjected to very high aero-convective heating environments.

  3. Ceramic membrane development in NGK

    NASA Astrophysics Data System (ADS)

    Araki, Kiyoshi; Sakai, Hitoshi

    2011-05-01

    NGK Insulators, Ltd. was established in 1919 to manufacture the electric porcelain insulators for power transmission lines. Since then, our business has grown as one of the world-leading ceramics manufacturing companies and currently supply with the various environmentally-benign ceramic products to worldwide. In this paper, ceramic membrane development in NGK is described in detail. We have been selling ceramic microfiltration (MF) membranes and ultra-filtration (UF) membranes for many years to be used for solid/liquid separation in various fields such as pharmaceutical, chemical, food and semiconductor industries. In Corporate R&D, new ceramic membranes with sub-nanometer sized pores, which are fabricated on top of the membrane filters as support, are under development for gas and liquid/liquid separation processes.

  4. Ceramic applications in turbine engines

    NASA Technical Reports Server (NTRS)

    Helms, H. E.; Heitman, P. W.; Lindgren, L. C.; Thrasher, S. R.

    1984-01-01

    The application of ceramic components to demonstrate improved cycle efficiency by raising the operating temperature of the existing Allison IGI 404 vehicular gas turbine engine is discussed. This effort was called the Ceramic Applications in Turbine Engines (CATE) program and has successfully demonstrated ceramic components. Among these components are two design configurations featuring stationary and rotating caramic components in the IGT 404 engine. A complete discussion of all phases of the program, design, materials development, fabrication of ceramic components, and testing-including rig, engine, and vehicle demonstation test are presented. During the CATE program, a ceramic technology base was established that is now being applied to automotive and other gas turbine engine programs. This technology base is outlined and also provides a description of the CATE program accomplishments.

  5. Ceramic component for electrodes

    DOEpatents

    Marchant, David D.; Bates, J. Lambert

    1980-01-01

    A ceramic component suitable for preparing MHD generator electrodes having the compositional formula: Y.sub.x (Mg.sub.y Cr.sub.z).sub.w Al.sub.(1-w) O.sub.3 where x=0.9 to 1.05, y=0.02 to 0.2, z=0.8 to 1.05 and w=1.0 to 0.5. The component is resistant to the formation of hydration products in an MHD environment, has good electrical conductivity and exhibits a lower electrochemical corrosion rate than do comparable compositions of lanthanum chromite.

  6. Ceramic heat pipe wick

    NASA Technical Reports Server (NTRS)

    Seidenberg, Benjamin (Inventor); Swanson, Theodore (Inventor)

    1989-01-01

    A wick for use in a capillary loop pump heat pipe is disclosed. The wick material is an essentially uniformly porous, permeable, open-cell, silicon dioxide/aluminum oxide inorganic ceramic foam having a silica fiber ratio, by weight, of about 78 to 22, respectively, a density of 6 lbs/cu ft, and an average pore size of less than 5 microns. A representative material having these characteristics is Lockheed Missile and Space Company, Inc.'s HTP 6-22. This material is fully compatible with the freons and anhydrous ammonia and allows for the use of these very efficient working fluids, and others, in capillary loops.

  7. Ceramic superconducting components

    NASA Technical Reports Server (NTRS)

    Haertling, G. H.

    1991-01-01

    An approach to the application of high-Tc ceramic superconductors to practical circuit elements was developed and demonstrated. This method, known as the rigid conductor process (RCP), involves the mounting of a preformed, sintered, and tested superconductor material onto an appropriate, rigid substrate with an epoxy adhesive which also serves to encapsulate the element from the ambient environment. Circuit elements such as straight conductors, coils and connectors were fabricated from YBa2Cu3O(7-x) superconducting material. Performance results are included for a low-noise low-thermal-conductivity superconducting grounding link for NASA.

  8. Design and test of current limiting modules using YBCO-coated conductors

    NASA Astrophysics Data System (ADS)

    Schmidt, W.; Gamble, B.; Kraemer, H.-P.; Madura, D.; Otto, A.; Romanosky, W.

    2010-01-01

    Within the cooperation between American Superconductor Corporation (AMSC) and Siemens Corporate Technology we have investigated the fault current limiting performance of YBCO-coated conductors (also called second-generation or 2G HTS wires) stabilized with stainless steel laminates. Design rules for the length and width of the wire depending on utility grid requirements have been established. Bifilar coils have been manufactured and tested with a typical limitation period of 50 ms under stepwise increasing voltage loads to determine the maximum temperature the wires can withstand without degradation. Coils have been assembled into limiter modules demonstrating uniform tripping of the individual coils and recovery within seconds. At present this cooperation is proceeding within a joint project funded by the US Department of Energy (DOE) that encompasses the design, construction and testing of a 115 kV FCL for power transmission within a time frame of 4-5 years, and additional partners. Besides AMSC and Siemens, Nexans contributes the high voltage terminations and Los Alamos National Lab investigates the ac losses. Installation and testing are planned for a Southern California Edison substation. The module planned for the transmission voltage application consists of 63 horizontally arranged coils connected in parallel and series to account for a rated current of 1.2 kArms and voltage of 31 kVrms plus margins. The rated voltage of the module is considerably lower than the line to ground voltage in the 115 kV grid owing to our shunted limiter concept. The shunt reactor connected in parallel to the module outside the cryostat allows for adjustment of the limited current and reduces voltage drop across the module in case of a fault. The fault current reduction ratio is 42% for our present design. A subscale module comprising six full-size coils has been assembled and tested recently to validate the coil performance and coil winding technique. The module had a critical

  9. Recent advances in the field of ceramic fibers and ceramic matrix composites

    NASA Astrophysics Data System (ADS)

    Naslain, R.

    2005-03-01

    Progress achieved during the last decade in the field of ceramic fibers and related ceramic matrix composites is reviewed. Both SiC-based and alumina-based fine fibers have been improved in terms of thermal stability and creep resistance with temperature limit of about 1400 and 1200 ° C, respectively. Two concepts for achieving damage-tolerant ceramic matrix composites have been identified : (i) that of non-oxide composites with a dense matrix in which matrix cracks formed under load are deflected and arrested in a weak fiber coating referred to as the interphase and (ii) that of all-oxide composites with a highly porous matrix with no need of any fiber coating. The lifetime under load of non-oxide composites in oxidizing atmospheres, is improved through the use of multilayered self-healing interphases and matrices deposited from gaseous precursors by chemical vapor infiltration (CVI). Lifetime ranging from 1000 to 10,000 hours at 1200 ° C under cyclic loading in air are foreseen. Alumina-based composites although attractive for long term exposures in oxidizing atmospheres up to ≈1200 ° C, are still experimental materials.

  10. High-temperature corrosion resistance of ceramics and ceramic coatings

    SciTech Connect

    Tortorelli, P.F.

    1996-06-01

    Ceramics and ceramic composites offer the potential to operate fossil energy systems at the higher temperatures necessary for improved energy efficiency and better environmental control. However, because many fossil fuel-derived processes contain sulfur, chlorine, and carbon, as well as oxygen, degradation from high-temperature corrosion and environmental effects arising from reactions of solids with gases and condensable products is a common life-determining factor in operating systems. Ceramic-based products are not immune to such degradation; adequate corrosion resistance must be assured to exploit the technical and economic potential of such materials. This is normally accomplished by using stable, sound oxides that exist in their bulk form, that naturally grow as surface layers upon exposure to an oxidizing environment, or that are deposited as a coating on a susceptible material. It is therefore important to examine the critical issues with respect to more environmental stability of ceramics that have the potential to be corrosion resistant in particular fossil environments. Key aspects include not only chemical compatibility, but the influence of the environment on the mechanical behavior of the ceramic materials. In addition, for coatings, the mechanical reliability of the ceramic is a key issue in that an otherwise corrosion-resistant surface layer must remain sound and adherent in order to provide protection to the underlying substrate. The purpose of this work is to support the development of advanced ceramics and ceramic composites for applications in fossil environments by examining critical issues related to high-temperature corrosion resistance. More specifically, the overall objective of this task is to examine the chemical compatibility and reliability of potentially corrosion-resistant ceramics being developed as protective overcoats and/or structural materials as parts of other work elements funded by the AR&TD Program.

  11. Joining of ceramics for high temperature applications

    NASA Technical Reports Server (NTRS)

    Vilpas, Martti

    1987-01-01

    Summarized is a literature survey of the methods for joining ceramics to ceramics or ceramics to metals for high temperature applications. Also mechanical properties and potential applications of the joints are considered. The joining of ceramics is usually carried out by brazing or diffusion bonding. Especially the latter has been found useful, increasing the application of bonded ceramics. The possibility of using electron beam and laser beam welding for joining ceramics has also recently been investigated. The bonding of ceramics has found numerous applications typical for high operating temperatures, i.e., sensors and thermocouples.

  12. Ceramic-glass-ceramic seal by microwave heating

    DOEpatents

    Meek, Thomas T.; Blake, Rodger D.

    1985-01-01

    A method for producing a ceramic-glass-ceramic seal by microwaving, mixes a slurry of glass sealing material and coupling agent and applies same to ceramic workpieces. The slurry and workpieces are placed together, insulated and then microwaved at a power, time and frequency sufficient to cause a liquid phase reaction in the slurry. The reaction of the glass sealing material forms a chemically different seal than that which would be formed by conventional heating because it is formed by a diffusion rather than by wetting of the reactants.

  13. Ceramic-glass-ceramic seal by microwave heating

    DOEpatents

    Meek, T.T.; Blake, R.D.

    1983-10-04

    A method for producing a ceramic-glass-ceramic seal by microwaving, mixes a slurry of glass sealing material and coupling agent and applies same to ceramic workpieces. The slurry and workpieces are placed together, insulated and then microwaved at a power, time and frequency sufficient to cause a liquid phase reaction in the slurry. The reaction of the glass sealing material forms a chemically different seal than that which would be formed by conventional heating because it is formed by a diffusion rather than by wetting of the reactants.

  14. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2003-01-01

    In the present quarter, the possibility of using a more complex interfacial engineering approach to the development of reliable and stable oxygen transport perovskite ceramic membranes/metal seals is discussed. Experiments are presented and ceramic/metal interactions are characterized. Crack growth and fracture toughness of the membrane in the reducing conditions are also discussed. Future work regarding this approach is proposed are evaluated for strength and fracture in oxygen gradient conditions. Oxygen gradients are created in tubular membranes by insulating the inner surface from the reducing environment by platinum foils. Fracture in these test conditions is observed to have a gradient in trans and inter-granular fracture as opposed to pure trans-granular fracture observed in homogeneous conditions. Fracture gradients are reasoned to be due to oxygen gradient set up in the membrane, variation in stoichiometry across the thickness and due to varying decomposition of the parent perovskite. The studies are useful in predicting fracture criterion in actual reactor conditions and in understanding the initial evolution of fracture processes.

  15. Ceramic fiber reinforced filter

    DOEpatents

    Stinton, David P.; McLaughlin, Jerry C.; Lowden, Richard A.

    1991-01-01

    A filter for removing particulate matter from high temperature flowing fluids, and in particular gases, that is reinforced with ceramic fibers. The filter has a ceramic base fiber material in the form of a fabric, felt, paper of the like, with the refractory fibers thereof coated with a thin layer of a protective and bonding refractory applied by chemical vapor deposition techniques. This coating causes each fiber to be physically joined to adjoining fibers so as to prevent movement of the fibers during use and to increase the strength and toughness of the composite filter. Further, the coating can be selected to minimize any reactions between the constituents of the fluids and the fibers. A description is given of the formation of a composite filter using a felt preform of commercial silicon carbide fibers together with the coating of these fibers with pure silicon carbide. Filter efficiency approaching 100% has been demonstrated with these filters. The fiber base material is alternately made from aluminosilicate fibers, zirconia fibers and alumina fibers. Coating with Al.sub.2 O.sub.3 is also described. Advanced configurations for the composite filter are suggested.

  16. Radiation effects in ceramics

    NASA Astrophysics Data System (ADS)

    Hobbs, Linn W.; Clinard, Frank W.; Zinkle, Steven J.; Ewing, Rodney C.

    1994-10-01

    Ceramics represent a large class of solids with a wide spectrum of applicability, whose structures range from simple to complex, whose bonding runs from highly ionic to almost entirely covalent and, in some cases, partially metallic, and whose band structures yield wide-gap insulators, narrow-gap semiconductors or even superconductors. These solids exhibit responses to irradiation which are more complex than those for metals. In ceramic materials, atomic displacements can be produced by direct momentum transfer to often more than one distinguishable sublattice, and in some cases radiolytically by electronic excitations, and result in point defects which are in general not simple. Radiation-induced defect interaction, accumulation and aggregation modes differ significantly from those found in metals. Amorphization is a frequent option in response to high-density defect perturbation and is strongly related to structural topology. These fundamental responses to irradiation result in significant changes to important applicable properties, such as strength, toughness, electrical and thermal conductivities, dielectric response and optical behavior. The understanding of such phenomena is less well-understood than the simple responses of metals but is being increasingly driven by critical applications in fusion energy production, nuclear waste disposal and optical communications.

  17. Composite Ceramic Superconducting Wires for Electric Motor Applications

    DTIC Science & Technology

    1990-01-31

    densification , as Y-123 filaments can reach densities estimated around 95 % in only two seconds. Densification is accompanied by dramatic...rings, but to find a system that will work. Additional brush testing that still needs to be done is to look at the effects of speed and brush pressure on...D~T IC ,LL COPY cvm i CJ SIXTH QUARTERLY REPORT II • ’ FOR THE PROJECT I "COMPOSITE CERAMIC SUPERCONDUCTINGiWIRES FOR ELECTRIC MOTOR APPLICATIONS" 2

  18. Characterization of Mechanical Damage Mechanisms in Ceramic Composite Materials.

    DTIC Science & Technology

    1986-07-01

    Studies of Y203 - Containing Tetragonal ZrO2 Polycrystals (Y- TZP )", pp. 352-70 in Advances in Ceramics, Vol. 12, Science and Technology of Zirconia II...temperature dependent, and is interpreted in term-s of TE1l evidence of dislocation activity, and an hypothesized tetragonal -to- cubic transformation...tation and temperature dependent, and is interpreted in terms of TEM evi- dence of dislocation activity, and an hypothesized tetragonal -to- cubic

  19. Contemporary all-ceramic materials, part-1.

    PubMed

    Pilathadka, Shriharsha; Vahalova, Dagmar

    2007-01-01

    Over the past 35 years, multiple types of all-ceramic materials have been introduced as an ideal alternative for metal-fused to ceramic. This review covers state-of-the-art development of all-ceramic systems in terms of history, material composition, fabrication technologies, and structural and strength properties. These materials are proved to be ideal in terms of mechanical properties and biocompatibility, making metal-free ceramic restorations a realistic clinical alternative for conventional metal-fused-to ceramic.

  20. Wear of novel ceramic-on-ceramic bearings under adverse and clinically relevant hip simulator conditions.

    PubMed

    Al-Hajjar, Mazen; Jennings, Louise M; Begand, Sabine; Oberbach, Thomas; Delfosse, Daniel; Fisher, John

    2013-11-01

    Further development of ceramic materials for total hip replacement aim to increase fracture toughness and further reduce the incidence of bearing fracture. Edge loading due to translational mal positioning (microseparation) has replicated stripe wear, wear rates, and bimodal wear debris observed on retrievals. This method has replicated the fracture of early zirconia ceramic-on-ceramic bearings. This has shown the necessity of introducing microseparation conditions to the gait cycle when assessing the tribological performance of new hip replacement bearings. Two novel ceramic matrix composite materials, zirconia-toughened alumina (ZTA) and alumina-toughened zirconia (ATZ), were developed by Mathys Orthopädie GmbH. In this study, ATZ-on-ATZ and ZTA-on-ZTA bearing combinations were tested and compared with alumina-on-alumina (Al2O3-on-Al2O3) bearings under adverse microseparation and edge loading conditions using the Leeds II physiological anatomical hip joint simulator. The wear rate (±95% confidence limit) of ZTA-on-ZTA was 0.14 ± 0.10 mm(3)/million cycles and that of ATZ-on-ATZ was 0.06 ± 0.004 mm(3)/million cycles compared with a wear rate of 0.74 ± 1.73 mm(3)/million cycles for Al2O3-on-Al2O3 bearings. Stripe wear was evident on all bearing combinations; however, the stripe formed on the ATZ and ZTA femoral heads was thinner and shallower that that formed on the Al2O3 heads. Posttest phase composition measurements for both ATZ and ZTA materials showed no significant change in the monoclinic zirconia content. ATZ-on-ATZ and ZTA-on-ZTA showed superior wear resistance properties when compared with Al2O3-on-Al2O3 under adverse edge loading conditions.

  1. Advanced ceramics for environmental protection

    SciTech Connect

    Chambers, J.A.

    1994-12-31

    Advanced ceramic materials offer significant thermodynamic efficiency advantages over metals and alloys because of their higher use temperatures. Using ceramic components results in higher temperature industrial processes which convert fuels to energy more efficiently, reducing environmental emissions. Ceramics have always offered high temperature strength and superior corrosion and erosion resistance. However, brittleness, poor thermal stock resistance and catastrophic failure have slowed industrial adoptions of ceramics in environmental applications. This paper will focus on environmental applications of three new advanced ceramic materials that are overcoming these barriers to industrial utilization through improved toughness, reliability, and thermal shock performance. PRD-66, a layered oxide ceramic with outstanding thermal shock resistance and high use temperature with utility in catalyst support, insulation, and hot gas filtration applications, is discussed. Tough silicon carbide fiber reinforced silicon carbide (SiC/SiC) and carbon fiber reinforced silicon carbide (C/SiC) ceramic composites made by chemical vapor infiltration, and silicon carbide particulate reinforced alumina (SiC{sub p}/Al{sub 2}O{sub 3}) composites made through Lanxide Corporation`s DIMOX{trademark} directed metal oxidation process are described. Applications of these materials to pollution reduction and energy efficiency in medical and municipal waste incineration, heat management, aluminum remelting, pyrolysis, coal combustion and gasification, catalytic pollution control, and hot gas filtration, will be discussed.

  2. High pressure ceramic heat exchanger

    DOEpatents

    Harkins, Bruce D.; Ward, Michael E.

    1998-01-01

    Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present header assembly when used with recuperators reduces the brittle effect of a portion of the ceramic components. Thus, the present header assembly used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present header assembly is comprised of a first ceramic member, a second ceramic member, a strengthening reinforcing member being in spaced relationship to the first ceramic member and the second ceramic member. The header assembly is further comprised of a refractory material disposed in contacting relationship with the first ceramic member, the second ceramic member and the strengthening reinforcing member. The present header assembly provides a high strength load bearing header assembly having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures.

  3. High pressure ceramic heat exchanger

    DOEpatents

    Harkins, Bruce D.; Ward, Michael E.

    1999-01-01

    Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present header assembly when used with recuperators reduces the brittle effect of a portion of the ceramic components. Thus, the present header assembly used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present header assembly is comprised of a first ceramic member, a second ceramic member, a reinforcing member being in spaced relationship to the first ceramic member and the second ceramic member. The header assembly is further comprised of a refractory material disposed in contacting relationship with the first ceramic member, the second ceramic member and the reinforcing member and having a strengthening member wrapped around the refractory material. The present header assembly provides a high strength load bearing header assembly having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures.

  4. High pressure ceramic heat exchanger

    DOEpatents

    Harkins, B.D.; Ward, M.E.

    1998-09-22

    Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present header assembly when used with recuperators reduces the brittle effect of a portion of the ceramic components. Thus, the present header assembly used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present header assembly is comprised of a first ceramic member, a second ceramic member, a strengthening reinforcing member being in spaced relationship to the first ceramic member and the second ceramic member. The header assembly is further comprised of a refractory material disposed in contacting relationship with the first ceramic member, the second ceramic member and the strengthening reinforcing member. The present header assembly provides a high strength load bearing header assembly having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures. 5 figs.

  5. Comparative evaluation of ceramic bracket base designs.

    PubMed

    Bordeaux, J M; Moore, R N; Bagby, M D

    1994-06-01

    Since the initial introduction of ceramic brackets, base designs have been modified to reduce tooth damage during debonding. The purpose of this study was to compare shear and tensile bond strengths and fracture sites of four second-generation ceramic brackets: Allure IV (A) (GAC International, Inc., Central Islip, N.Y.), Ceramaflex (C) (TP Orthodontics, Inc., LaPorte, Ind.), Intrigue (I) (Lancer Orthodontics, Carlsbad, Calif.), Transcend 2000 (T) (Unitek Corp., Monrovia, Calif.), and a foil-mesh base stainless steel bracket, DynaBond II (D) (Unitek Corp., Monrovia, Calif.). Twenty brackets of each type were bonded to 100 mandibular bovine incisor teeth with Concise bonding adhesive. The samples were thermocycled for 24 hours and the brackets were debonded with an Instron universal testing machine (Instron Corp., Canton, Mass.). A modified Transcend debonding instrument was used for tensile debonding, whereas a chisel was used for shear debonding. An analysis of variance was performed with a 0.05 level of confidence. Mean shear strengths (kg/cm2) necessary to debond were 174.0 (A), 71.0 (C), 189.0 (I), 228.0 (T), and 160.0 (D). Mean tensile strengths (kg/cm2) were 27.0 (A), 26.7 (C), 51.3 (I), 56.5 (T), and 48.6 (D). Fracture sites examined with a light microscope showed no enamel damage with any of the ceramic brackets. Intrigue was the only bracket to fracture and had 30% bracket fracture in the tensile mode and 20% bracket fracture in the shear mode. The percentage of fractures at the adhesive-bracket base interface for shear and tensile modes, respectively, were 80, 100 (A); 100, 90 (C); 10, 60 (I); 60, 90 (T); and 90, 80 (D).(ABSTRACT TRUNCATED AT 250 WORDS)

  6. Fracture resistance of teeth restored with all-ceramic inlays and onlays: an in vitro study.

    PubMed

    Saridag, S; Sevimay, M; Pekkan, G

    2013-01-01

    Fracture resistance of inlays and onlays may be influenced by the quantity of the dental structure removed and the restorative materials used. The purpose of this in vitro study was to evaluate the effects of two different cavity preparation designs and all-ceramic restorative materials on the fracture resistance of the tooth-restoration complex. Fifty mandibular third molar teeth were randomly divided into the following five groups: group 1: intact teeth (control); group 2: inlay preparations, lithium-disilicate glass-ceramic (IPS e.max Press, Ivoclar Vivadent AG, Schaan, Liechtenstein); group 3: inlay preparations, zirconia ceramic (ICE Zirkon, Zirkonzahn SRL, Gais, Italy); group 4: onlay preparations, lithium-disilicate glass-ceramic (IPS e.max Press); and group 5: onlay preparations, zirconia ceramic (ICE Zirkon). The inlay and onlay restorations were adhesively cemented with dual polymerizing resin cement (Variolink II, Ivoclar Vivadent AG). After thermal cycling (5° to 55°C × 5000 cycles), specimens were subjected to a compressive load until fracture at a crosshead speed of 0.5 mm/min. Statistical analyses were performed using one-way analysis of variance and Tukey HSD tests. The fracture strength values were significantly higher in the inlay group (2646.7 ± 360.4) restored with lithium-disilicate glass-ceramic than those of the onlay group (1673.6 ± 677) restored with lithium-disilicate glass-ceramic. The fracture strength values of teeth restored with inlays using zirconia ceramic (2849 ± 328) and onlays with zirconia ceramic (2796.3 ± 337.3) were similar to those of the intact teeth (2905.3 ± 398.8). In the IPS e.max Press groups, as the preparation amount was increased (from inlay to onlay preparation), the fracture resistance was decreased. In the ICE Zirkon ceramic groups, the preparation type did not affect the fracture resistance results.

  7. Ceramics for Turbine Engine Applications.

    DTIC Science & Technology

    1980-03-01

    DEVELOPMENT OF CERAMIC NOZZLE SECTION FOR SMIALL RADIAL GAS TURBINE by J.C.Napier and J.P. Arnold 12 DEVELOPMENT OF A CERAMIC TURBINE NOZZLE RING by H.Burfeindt...this way, for instance, a Daimler engine was in 1911 awarded the prize of the "Automobiltechnische Gesell - schaft". In 1912, a Benz engine won the...blade development Turtle U~nion RB 199 v)ln BENEFITS OF CERAMICS TO GAS TURBINES by Arnold Brooks and Albert I. Bellin Aircraft Engine Group General

  8. Evaluation of the marginal fit of full ceramic crowns by the microcomputed tomography (micro-CT) technique

    PubMed Central

    Demir, Necla; Ozturk, Atiye Nilgun; Malkoc, Meral Arslan

    2014-01-01

    Objective: To evaluate the marginal gap (MG) and absolute marginal discrepancy (MD) of full ceramic crowns with two finish line designs, shoulder and chamfer, using microcomputed tomography (micro-CT) before and after cementation. Materials and Methods: Sixty extracted human maxillary premolar teeth were divided into two groups based on the finish line design: Group I: 90° shoulder and Group II: 135° chamfer. The specimens were further grouped based on the type of full ceramic crown they received: Group A: Feldspathic Cerec inLab ceramic system, Group B: Cerec inLab aluminum oxide ceramic system and Group C: Lithium disilicate press ceramic system. Before cementation, five crowns from each group were scanned using micro-CT in two sections, sagittal and coronal, to determine the MG and MD values for four regions of the crown (sagittal buccal, sagittal lingual, coronal mesial and coronal distal). After cementation and thermal cycling, the scanning was repeated. Measurements were obtained from 10 points for each region, 80 points totally, to evaluate the MG and MD values. Files were processed using NRecon and CTAn software. Results were statistically analyzed using one- and two-way ANOVA and Tukey HSD tests (P = 0.05). Results: Full ceramic systems showed clinically acceptable marginal adaptation values. The Feldspathic Cerec inLab ceramic system generally presented the lowest variance, except in the MG values of the coronal mesial region. The MG and MD values of all ceramics increased significantly after cementation, except in the shoulder preparation design (sagittal buccal region) for MG and in the chamfer preparation design (sagittal lingual region) for MD values. Conclusions: Full-ceramic crowns showed clinically acceptable marginal adaptation values. The Feldspathic Cerec inLab ceramic system (Vitablocs Mark II) generally presented the lowest variance when compared with the other ceramics, except for the MG values on the mesial surface of the coronal section

  9. Dispersed metal-toughened ceramics and ceramic brazing

    SciTech Connect

    Moorhead, A.J.; Tiegs, T.N.; Lauf, R.J.

    1983-01-01

    An alumina (Al/sub 2/O/sub 3/) based material that contains approximately 1 vol % finely dispersed platinum or chromium was developed for use in high temperature thermal-shock resistant electrical insulators. The work at ORNL is divided into two areas: (1) development of DMT ceramics; and (2) development of brazing filler metals suitable for making ceramic-to-ceramic and ceramic-to-metal brazements. The DMT ceramics and brazements are intended for service at elevated temperatures and at high stress levels in the dirty environments of advanced heat engines. The development and characterization of DMT ceramics includes processing (powder preparation, densification and heat treatment) and detailed measurement of mechanical and physical properties (strength, fracture toughness, and thermal conductivity). The brazing work includes: (1) the formulation and melting of small quantities of experimental brazing filler metals; (2) evaluation of the wetting and bonding behavior of these filler metals on Al/sub 2/O/sub 3/, partially stabilized zirconia and ..cap alpha..-SiC in a sessile drop apparatus; and (3) determine the short-term strength and fracture toughness of brazements.

  10. Ceramic turbine nozzle

    DOEpatents

    Shaffer, James E.; Norton, Paul F.

    1996-01-01

    A turbine nozzle and shroud assembly having a preestablished rate of thermal expansion is positioned in a gas turbine engine and being attached to conventional metallic components. The metallic components having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the turbine nozzle vane assembly. The turbine nozzle vane assembly includes a plurality of segmented vane defining a first vane segment and a second vane segment. Each of the first and second vane segments having a vertical portion. Each of the first vane segments and the second vane segments being positioned in functional relationship one to another within a recess formed within an outer shroud and an inner shroud. The turbine nozzle and shroud assembly provides an economical, reliable and effective ceramic component having a preestablished rate of thermal expansion being less than the preestablished rate of thermal expansion of the other component.

  11. Ceramic turbine nozzle

    DOEpatents

    Shaffer, J.E.; Norton, P.F.

    1996-12-17

    A turbine nozzle and shroud assembly having a preestablished rate of thermal expansion is positioned in a gas turbine engine and being attached to conventional metallic components. The metallic components have a preestablished rate of thermal expansion greater than the preestablished rate of thermal expansion of the turbine nozzle vane assembly. The turbine nozzle vane assembly includes a plurality of segmented vane defining a first vane segment and a second vane segment, each of the first and second vane segments having a vertical portion, and each of the first vane segments and the second vane segments being positioned in functional relationship one to another within a recess formed within an outer shroud and an inner shroud. The turbine nozzle and shroud assembly provides an economical, reliable and effective ceramic component having a preestablished rate of thermal expansion being less than the preestablished rate of thermal expansion of the other component. 4 figs.

  12. Lead zirconate titanate ceramics

    SciTech Connect

    Walker, B.E. Jr.

    1986-12-02

    This patent describes a lead zirconate titanate (PZT) piezoelectric ceramic composition which, based on total composition weight, consists essentially of a solid solution of lead zirconate and lead titanate in a PbZrO/sub 3/:PbTiO/sub 3/ ratio from about 0.505:0.495 to about 0.54:0.46; a halide salt selected from the group consisting of fluorides and chlorides of alkali metal and alkaline earth elements and mixtures thereof except for francium and radium in an amount from about 0.5 to 2 weight percent; and an oxide selected from the group consisting of magnesium, barium, scandium, aluminum, lanthanum, praesodynium, neodymium, samarium, and mixtures thereof in an amount from about 0.5 to about 6 weight percent, the relative amount of oxide being from about 1 to about 4 times that of the halide.

  13. Creep in electronic ceramics

    SciTech Connect

    Routbort, J. L.; Goretta, K. C.; Arellano-Lopez, A. R.

    2000-04-27

    High-temperature creep measurements combined with microstructural investigations can be used to elucidate deformation mechanisms that can be related to the diffusion kinetics and defect chemistry of the minority species. This paper will review the theoretical basis for this correlation and illustrate it with examples from some important electronic ceramics having a perovskite structure. Recent results on BaTiO{sub 3}, (La{sub 1{minus}x}Sr){sub 1{minus}y}MnO{sub 3+{delta}}, YBa{sub 2}Cu{sub 3}O{sub x}, Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub x}, (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} and Sr(Fe,Co){sub 1.5}O{sub x} will be presented.

  14. Lightweight Ceramic Insulation

    NASA Technical Reports Server (NTRS)

    Wheeler, W. H.; Creedon, J. F.

    1986-01-01

    Fiber burnout process yields low densities. Low density attained by process of sacrificial burnout. Graphite or carbon fibers mixed into slurry of silica, alumina, and boron-compound fibers in amounts ranging from 25 to 75 percent of total fiber content by weight. Mixture formed into blocks and dried. Blocks placed in kiln and heated to 1,600 degrees F(870 degrees C) for several hours. Graphite or carbon fibers slowly oxidize away, leaving voids and reducing block density. Finally, blocks heated to 2,350 degrees F (1,290 degrees C) for 90 minutes to bond remaining ceramic fibers together. Developed for use on Space Shuttle and other spacecraft, rigid insulation machined to requisite shape and bonded in place.

  15. NDE of structural ceramics

    NASA Technical Reports Server (NTRS)

    Klima, S. J.; Vary, A.

    1986-01-01

    Radiographic, ultrasonic, scanning laser acoustic microscopy (SLAM), and thermo-acoustic microscopy techniques were used to characterize silicon nitride and silicon carbide modulus-of-rupture test specimens in various stages of fabrication. Conventional and microfocus X-ray techniques were found capable of detecting minute high density inclusions in as-received powders, green compacts, and fully densified specimens. Significant density gradients in sintered bars were observed by radiography, ultrasonic velocity, and SLAM. Ultrasonic attenuation was found sensitive to microstructural variations due to grain and void morphology and distribution. SLAM was also capable of detecting voids, inclusions and cracks in finished test bars. Consideration is given to the potential for applying thermo-acoustic microscopy techniques to green and densified ceramics. The detection probability statistics and some limitations of radiography and SLAM also are discussed.

  16. Ceramic Cerami Turbine Nozzle

    DOEpatents

    Boyd, Gary L.

    1997-04-01

    A turbine nozzle vane assembly having a preestablished rate of thermal expansion is positioned in a gas turbine engine and being attached to conventional metallic components. The metallic components having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the turbine nozzle vane assembly. The turbine nozzle vane assembly includes an outer shroud and an inner shroud having a plurality of horizontally segmented vanes therebetween being positioned by a connecting member positioning segmented vanes in functional relationship one to another. The turbine nozzle vane assembly provides an economical, reliable and effective ceramic component having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the other component.

  17. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2003-01-01

    In the present quarter, experiments are presented on ceramic/metal interactions of Zirconia/Ni-B-Si system and with a thin Ti coating deposited on zirconia surface. Processing of perovskites of LSC, LSF and LSCF composition for evaluation of mechanical properties as a function of environment are begun. The studies are to be in parallel with LSFCO composition to characterize the segregation of cations and slow crack growth in environmental conditions. La{sub 1-x}Sr{sub x}FeO{sub 3-d} has also been characterized for paramagnetic ordering at room temperature and the evolution of magnetic moments as a function of temperature are investigated. Investigation on the thermodynamic properties of the membrane materials are continued to develop a complete model for the membrane transport.

  18. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2002-07-01

    In the present quarter, oxygen transport perovskite ceramic membranes are evaluated for strength and fracture in oxygen gradient conditions. Oxygen gradients are created in tubular membranes by insulating the inner surface from the reducing environment by platinum foils. Fracture in these test conditions is observed to have a gradient in trans and inter-granular fracture as opposed to pure trans-granular fracture observed in homogeneous conditions. Fracture gradients are reasoned to be due to oxygen gradient set up in the membrane, variation in stoichiometry across the thickness and due to varying decomposition of the parent perovskite. The studies are useful in predicting fracture criterion in actual reactor conditions and in understanding the initial evolution of fracture processes.

  19. A flux pumping method applied to the magnetization of YBCO superconducting coils: frequency, amplitude and waveform characteristics

    NASA Astrophysics Data System (ADS)

    Fu, Lin; Matsuda, Koichi; Lecrevisse, Thibault; Iwasa, Yukikazu; Coombs, Tim

    2016-04-01

    This letter presents a flux pumping method and the results gained when it was used to magnetize a range of different YBCO coils. The pumping device consists of an iron magnetic circuit with eight copper coils which apply a traveling magnetic field to the superconductor. The copper poles are arranged vertically with an air gap length of 1 mm and the iron cores are made of laminated electric steel plates to minimize eddy-current losses. We have used this arrangement to investigate the best possible pumping result when parameters such as frequency, amplitude and waveform are varied. We have successfully pumped current into the superconducting coil up to a value of 90% of I c and achieved a resultant magnetic field of 1.5 T.

  20. The influence of post-growth thermal treatments on the critical current density of TSMG YBCO bulk superconductors

    NASA Astrophysics Data System (ADS)

    Diko, P.; Antal, V.; Zmorayová, K.; Šefčiková, M.; Chaud, X.; Kováč, J.; Yao, X.; Chen, I.; Eisterer, M.; Weber, H. W.

    2010-12-01

    Oxygenation and thermochemical post-growth treatments of top seeded melt-growth (TSMG) YBCO bulk superconductors can significantly influence critical current density. It is shown that, depending on oxygenation conditions and the size of 211 particles, different reductions of intrinsic critical current density values can be obtained due to the reduction in the sample cross-section caused by the presence of a/b-microcracks induced by 211 particles, and a/b- and a/c-cracks induced by oxygenation. The possibility of eliminating oxygenation cracks by high pressure oxygenation and consequently significantly increasing the macroscopic critical current density is demonstrated. An effective dopant concentration for chemical pinning is proposed and possible clustering of substitutions in the Y123 lattice by thermochemical treatments is shown.

  1. Fabrication and Characterization of Ultrathin PBCO/YBCO/PBCO Constrictions for Hot Electron Bolometer THz Mixing Application

    NASA Astrophysics Data System (ADS)

    Peroz, Christophe; Degardin, Annick F.; Villegier, Jean-Claude; Kreisler, Alain J.

    2007-06-01

    Superconducting Hot Electron Bolometer (HEB) mixers are a competitive alternative to conventional mixer technologies in the terahertz range because of their ultrawide bandwidth, high conversion gain, and low intrinsic noise level, even at 77 K. A technological process to realize HEBs based on high-Tc YBa2Cu3O7-delta (YBCO) materials is described. Ultra-thin 12 to 40 nm layers were sputtered on MgO (100) substrates, sub-micrometer constrictions (0.5 mum times 0.5 mum) were etched on these and log-periodic gold antennas were then integrated. Good superconducting properties were measured after the whole process. Electrical transport characteristics of the device are discussed, aging effects are considered and regular bolometric THz response results are given.

  2. Quantitative magneto-optical analysis of the role of finite temperatures on the critical state in YBCO thin films

    NASA Astrophysics Data System (ADS)

    Albrecht, Joachim; Brück, Sebastian; Stahl, Claudia; Ruoß, Stephen

    2016-11-01

    We use quantitative magneto-optical microscopy to investigate the influence of finite temperatures on the critical state of thin YBCO films. In particular, temperature and time dependence of supercurrents in inhomogeneous and anisotropic films are analyzed to extract the role of temperature on the supercurrents themselves and the influence of thermally activated relaxation. We find that inhomogeneities and anisotropies of the current density distribution correspond to a different temperature dependence of local supercurrents. In addition, the thermally activated decay of supercurrents can be used to extract local vortex pinning energies. With these results the modification of vortex pinning introduced by substrate structures is studied. In summary the local investigation of supercurrent densities allows the full description of the vortex pinning landscape with respect to pinning forces and energies in superconducting films with complex properties under the influence of finite temperatures.

  3. Ceramic automotive Stirling engine study

    NASA Technical Reports Server (NTRS)

    Musikant, S.; Chiu, W.; Darooka, D.; Mullings, D. M.; Johnson, C. A.

    1985-01-01

    A conceptual design study for a Ceramic Automotive Stirling Engine (CASE) is performed. Year 1990 structural ceramic technology is assumed. Structural and performance analyses of the conceptual design are performed as well as a manufacturing and cost analysis. The general conclusions from this study are that such an engine would be 10-26% more efficient over its performance map than the current metal Automotive Stirling Reference Engine (ASRE). Cost of such a ceramic engine is likely to be somewhat higher than that of the ASRE but engine cost is very sensitive to the ultimate cost of the high purity, ceramic powder raw materials required to fabricate high performance parts. When the design study is projected to the year 2000 technology, substantinal net efficiency improvements, on the order of 25 to 46% over the ASRE, are computed.

  4. Ceramic regenerator systems development program

    NASA Technical Reports Server (NTRS)

    Fucinari, C. A.; Rahnke, C. J.; Rao, V. D. N.; Vallance, J. K.

    1980-01-01

    The DOE/NASA Ceramic Regenerator Design and Reliability Program aims to develop ceramic regenerator cores that can be used in passenger car and industrial/truck gas turbine engines. The major cause of failure of early gas turbine regenerators was found to be chemical attack of the ceramic material. Improved materials and design concepts aimed at reducing or eliminating chemical attack were placed on durability test in Ford 707 industrial gas turbine engines late in 1974. Results of 53,065 hours of turbine engine durability testing are described. Two materials, aluminum silicate and magnesium aluminum silicate, show promise. Five aluminum silicate cores attained the durability objective of 10,000 hours at 800 C (1472 F). Another aluminum silicate core shows minimal evidence of chemical attack after 8071 hours at 982 C (1800 F). Results obtained in ceramic material screening tests, aerothermodynamic performance tests, stress analysis, cost studies, and material specifications are included.

  5. Inorganic glass ceramic slip rings

    NASA Technical Reports Server (NTRS)

    Glossbrenner, E. W.; Cole, S. R.

    1972-01-01

    Prototypes of slip rings have been fabricated from ceramic glass, a material which is highly resistant to deterioration due to high temperature. Slip ring assemblies were not structurally damaged by mechanical tests and performed statisfactorily for 200 hours.

  6. Process for producing advanced ceramics

    DOEpatents

    Kwong, Kyei-Sing

    1996-01-01

    A process for the synthesis of homogeneous advanced ceramics such as SiC+AlN, SiAlON, SiC+Al.sub.2 O.sub.3, and Si.sub.3 N.sub.4 +AlN from natural clays such as kaolin, halloysite and montmorillonite by an intercalation and heat treatment method. Included are the steps of refining clays, intercalating organic compounds into the layered structure of clays, drying the intercalated mixture, firing the treated atmospheres and grinding the loosely agglomerated structure. Advanced ceramics produced by this procedure have the advantages of homogeneity, cost effectiveness, simplicity of manufacture, ease of grind and a short process time. Advanced ceramics produced by this process can be used for refractory, wear part and structure ceramics.

  7. Nondestructive characterization of micromachined ceramics

    NASA Astrophysics Data System (ADS)

    Cooney, Adam; Hix, Kenneth E.; Yaney, Perry; Zhan, Qiwen; Dosser, Larry R.; Blackshire, James L.

    2005-05-01

    The aerospace, automotive, and electronic industries are finding increasing need for components made from silicon carbide (SiC) and silicon nitride (Si3N4). The development and use of miniaturized ceramic parts, in particular, is of significant interest in a variety of critical applications. As these application areas grow, manufacturers are being asked to find new and better solutions for machining and forming ceramic materials with microscopic precision. Recent advances in laser machining technologies are making precision micromachining of ceramics a reality. Questions regarding micromachining accuracy, residual melt region effects, and laser-induced microcracking are of critical concern during the machining process. In this activity, a variety of nondestructive inspection methods have been used to investigate the microscopic features of laser-machined ceramic components. The primary goal was to assess the micromachined areas for machining accuracy and microcracking using laser ultrasound, scanning electron microscopy, and white-light interference microscopic imaging of the machined regions.

  8. Ceramic powder for sintering materials

    NASA Technical Reports Server (NTRS)

    Akiya, H.; Saito, A.

    1984-01-01

    Surface activity of ceramic powders such as MgO and Al2O3, for use in sintering with sp. emphasis on their particle size, shape, particle size distribution, packing, and coexisting additives and impurities are reviewed.

  9. Nonlinear fracture of concrete and ceramics

    NASA Technical Reports Server (NTRS)

    Kobayashi, Albert S.; Du, Jia-Ji; Hawkins, Niel M.; Bradt, Richard C.

    1989-01-01

    The nonlinear fracture process zones in an impacted unnotched concrete bend specimen, a prenotched ceramic bend specimen, and an unnotched ceramic/ceramic composite bend specimen were estimated through hybrid experimental numerical analysis. Aggregate bridging in concrete, particulate bridging in ceramics, and fiber bridging in ceramic/ceramic composite are modeled by Barenblatt-type cohesive zones which are incorporated into the finite-element models of the bend specimens. Both generation and propagation analyses are used to estimate the distribution of crack closure stresses in the nonlinear fracture process zones. The finite-element models are then used to simulate fracture tests consisting of rapid crack propagation in an impacted concrete bend specimen, and stable crack growth and strain softening in a ceramic and ceramic/ceramic composite bend specimens.

  10. Extruded ceramic honeycomb and method

    DOEpatents

    Day, J. Paul

    1995-04-04

    Extruded low-expansion ceramic honeycombs comprising beta-spodumene solid solution as the principal crystal phase and with less than 7 weight percent of included mullite are produced by compounding an extrusion batch comprising a lithium aluminosilicate glass powder and a clay additive, extruding a green honeycomb body from the batch, and drying and firing the green extruded cellular honeycomb to crystallize the glass and clay into a low-expansion spodumene ceramic honeycomb body.

  11. Heat distribution ceramic processing method

    DOEpatents

    Tiegs, Terry N.; Kiggans, Jr., James O.

    2001-01-01

    A multi-layered heat distributor system is provided for use in a microwave process. The multi-layered heat distributors includes a first inner layer of a high thermal conductivity heat distributor material, a middle insulating layer and an optional third insulating outer layer. The multi-layered heat distributor system is placed around the ceramic composition or article to be processed and located in a microwave heating system. Sufficient microwave energy is applied to provide a high density, unflawed ceramic product.

  12. Method for preparing ceramic composite

    DOEpatents

    Alexander, K.B.; Tiegs, T.N.; Becher, P.F.; Waters, S.B.

    1996-01-09

    A process is disclosed for preparing ceramic composite comprising blending TiC particulates, Al{sub 2}O{sub 3} particulates and nickel aluminide and consolidating the mixture at a temperature and pressure sufficient to produce a densified ceramic composite having fracture toughness equal to or greater than 7 MPa m{sup 1/2}, a hardness equal to or greater than 18 GPa. 5 figs.

  13. Batch compositions for cordierite ceramics

    DOEpatents

    Hickman, David L.

    1994-07-26

    Ceramic products consisting principally of cordierite and a method for making them are provided, the method employing batches comprising a mineral component and a chemical component, the mineral component comprising clay and talc and the chemical component consisting essentially of a combination of the powdered oxides, hydroxides, or hydrous oxides of magnesium, aluminum and silicon. Ceramics made by extrusion and firing of the batches can exhibit low porosity, high strength and low thermal expansion coefficients.

  14. High-temperature ceramic receivers

    SciTech Connect

    Jarvinen, P. O.

    1980-01-01

    An advanced ceramic dome cavity receiver is discussed which heats pressurized gas to temperatures above 1800/sup 0/F (1000/sup 0/C) for use in solar Brayton power systems of the dispersed receiver/dish or central receiver type. Optical, heat transfer, structural, and ceramic material design aspects of the receiver are reported and the development and experimental demonstration of a high-temperature seal between the pressurized gas and the high-temperature silicon carbide dome material is described.

  15. Casting Of Multilayer Ceramic Tapes

    NASA Technical Reports Server (NTRS)

    Collins, Earl R., Jr.

    1991-01-01

    Procedure for casting thin, multilayer ceramic membranes, commonly called tapes, involves centrifugal casting at accelerations of 1,800 to 2,000 times normal gravitational acceleration. Layers of tape cast one at a time on top of any previous layer or layers. Each layer cast from slurry of ground ceramic suspended in mixture of solvents, binders, and other components. Used in capacitors, fuel cells, and electrolytic separation of oxygen from air.

  16. Method for preparing ceramic composite

    DOEpatents

    Alexander, Kathleen B.; Tiegs, Terry N.; Becher, Paul F.; Waters, Shirley B.

    1996-01-01

    A process for preparing ceramic composite comprising blending TiC particulates, Al.sub.2 O.sub.3 particulates and nickle aluminide and consolidating the mixture at a temperature and pressure sufficient to produce a densified ceramic composite having fracture toughness equal to or greater than 7 MPa m.sup.1/2, a hardness equal to or greater than 18 GPa.

  17. Metal-ceramic joint assembly

    DOEpatents

    Li, Jian

    2002-01-01

    A metal-ceramic joint assembly in which a brazing alloy is situated between metallic and ceramic members. The metallic member is either an aluminum-containing stainless steel, a high chromium-content ferritic stainless steel or an iron nickel alloy with a corrosion protection coating. The brazing alloy, in turn, is either an Au-based or Ni-based alloy with a brazing temperature in the range of 9500 to 1200.degree. C.

  18. High-Temperature Ceramic Superconductors

    DTIC Science & Technology

    1991-12-15

    magnetic susceptibility, Meissner effect and specific heat. Task 4 is an investigation of superconductor ceramic processing. Most of the important... effect of the additional heater on the microstructure is shown in Fig. 11. As the upper micrograph shows, hardly any alignment was induced with a single... effect in cal field,7 H 1 = 𔃻o In K/41TA 2, and magnetic field pene- limiting the current-carrying capability of the ceramic tration length, A. The

  19. Microwave sintering of ceramic materials

    NASA Astrophysics Data System (ADS)

    Karayannis, V. G.

    2016-11-01

    In the present study, the potential of microwave irradiation as an innovative energy- efficient alternative to conventional heating technologies in ceramic manufacturing is reviewed, addressing the advantages/disadvantages, while also commenting on future applications of possible commercial interest. Ceramic materials have been extensively studied and used due to several advantages they exhibit. Sintering ceramics using microwave radiation, a novel technology widely employed in various fields, can be an efficient, economic and environmentally-friendlier approach, to improve the consolidation efficiency and reduce the processing cycle-time, in order to attain substantial energy and cost savings. Microwave sintering provides efficient internal heating, as energy is supplied directly and penetrates the material. Since energy transfer occurs at a molecular level, heat is generated throughout the material, thus avoiding significant temperature gradients between the surface and the interior, which are frequently encountered at high heating rates upon conventional sintering. Thus, rapid, volumetric and uniform heating of various raw materials and secondary resources for ceramic production is possible, with limited grain coarsening, leading to accelerated densification, and uniform and fine-grained microstructures, with enhanced mechanical performance. This is particularly important for manufacturing large-size ceramic products of quality, and also for specialty ceramic materials such as bioceramics and electroceramics. Critical parameters for the process optimization, including the electromagnetic field distribution, microwave-material interaction, heat transfer mechanisms and material transformations, should be taken into consideration.

  20. Method for Waterproofing Ceramic Materials

    NASA Technical Reports Server (NTRS)

    Cagliostro, Domenick E. (Inventor); Hsu, Ming-Ta S. (Inventor)

    1998-01-01

    Hygroscopic ceramic materials which are difficult to waterproof with a silane, substituted silane or silazane waterproofing agent, such as an alumina containing fibrous, flexible and porous, fibrous ceramic insulation used on a reentry space vehicle, are rendered easy to waterproof if the interior porous surface of the ceramic is first coated with a thin coating of silica. The silica coating is achieved by coating the interior surface of the ceramic with a silica precursor converting the precursor to silica either in-situ or by oxidative pyrolysis and then applying the waterproofing agent to the silica coated ceramic. The silica precursor comprises almost any suitable silicon containing material such as a silane, silicone, siloxane, silazane and the like applied by solution, vapor deposition and the like. If the waterproofing is removed by e.g., burning, the silica remains and the ceramic is easily rewaterproofed. An alumina containing TABI insulation which absorbs more that five times its weight of water, absorbs less than 10 wt. % water after being waterproofed according to the method of the invention.

  1. Wedge edge ceramic combustor tile

    DOEpatents

    Shaffer, J.E.; Holsapple, A.C.

    1997-06-10

    A multipiece combustor has a portion thereof being made of a plurality of ceramic segments. Each of the plurality of ceramic segments have an outer surface and an inner surface. Each of the plurality of ceramic segments have a generally cylindrical configuration and including a plurality of joints. The joints define joint portions, a first portion defining a surface being skewed to the outer surface and the inner surface. The joint portions have a second portion defining a surface being skewed to the outer surface and the inner surface. The joint portions further include a shoulder formed intermediate the first portion and the second portion. The joints provide a sealing interlocking joint between corresponding ones of the plurality of ceramic segments. Thus, the multipiece combustor having the plurality of ceramic segment with the plurality of joints reduces the physical size of the individual components and the degradation of the surface of the ceramic components in a tensile stress zone is generally eliminated reducing the possibility of catastrophic failures. 7 figs.

  2. Wedge edge ceramic combustor tile

    DOEpatents

    Shaffer, James E.; Holsapple, Allan C.

    1997-01-01

    A multipiece combustor has a portion thereof being made of a plurality of ceramic segments. Each of the plurality of ceramic segments have an outer surface and an inner surface. Each of the plurality of ceramic segments have a generally cylindrical configuration and including a plurality of joints. The joints define joint portions, a first portion defining a surface being skewed to the outer surface and the inner surface. The joint portions have a second portion defining a surface being skewed to the outer surface and the inner surface. The joint portions further include a shoulder formed intermediate the first portion and the second portion. The joints provide a sealing interlocking joint between corresponding ones of the plurality of ceramic segments. Thus, the multipiece combustor having the plurality of ceramic segment with the plurality of joints reduces the physical size of the individual components and the degradation of the surface of the ceramic components in a tensile stress zone is generally eliminated reducing the possibility of catastrophic failures.

  3. Failure Analysis of Ceramic Components

    SciTech Connect

    B.W. Morris

    2000-06-29

    Ceramics are being considered for a wide range of structural applications due to their low density and their ability to retain strength at high temperatures. The inherent brittleness of monolithic ceramics requires a departure from the deterministic design philosophy utilized to analyze metallic structural components. The design program ''Ceramic Analysis and Reliability Evaluation of Structures Life'' (CARES/LIFE) developed by NASA Lewis Research Center uses a probabilistic approach to predict the reliability of monolithic components under operational loading. The objective of this study was to develop an understanding of the theories used by CARES/LIFE to predict the reliability of ceramic components and to assess the ability of CARES/LIFE to accurately predict the fast fracture behavior of monolithic ceramic components. A finite element analysis was performed to determine the temperature and stress distribution of a silicon carbide O-ring under diametral compression. The results of the finite element analysis were supplied as input into CARES/LIFE to determine the fast fracture reliability of the O-ring. Statistical material strength parameters were calculated from four-point flexure bar test data. The predicted reliability showed excellent correlation with O-ring compression test data indicating that the CARES/LIFE program can be used to predict the reliability of ceramic components subjected to complicated stress states using material properties determined from simple uniaxial tensile tests.

  4. FOREWORD: Focus on Advanced Ceramics Focus on Advanced Ceramics

    NASA Astrophysics Data System (ADS)

    Ohashi, Naoki

    2011-06-01

    Much research has been devoted recently to developing technologies for renewable energy and improving the efficiency of the processes and devices used in industry and everyday life. Efficient solutions have been found using novel materials such as platinum and palladium-based catalysts for car exhaust systems, samarium-cobalt and neodymium-iron-boron permanent magnets for electrical motors, and so on. However, their realization has resulted in an increasing demand for rare elements and in their deficit, the development of new materials based on more abundant elements and new functionalities of traditional materials. Moreover, increasing environmental and health concerns demand substitution of toxic or hazardous substances with nature-friendly alternatives. In this context, this focus issue on advanced ceramics aims to review current trends in ceramics science and technology. It is related to the International Conference on Science and Technology of Advanced Ceramics (STAC) held annually to discuss the emerging issues in the field of ceramics. An important direction of ceramic science is the collaboration between experimental and theoretical sciences. Recent developments in density functional theory and computer technology have enabled the prediction of physical and chemical properties of ceramics, thereby assisting the design of new materials. Therefore, this focus issue includes articles devoted to theory and advanced characterization techniques. As mentioned above, the potential shortage of rare elements is becoming critical to the industry and has resulted in a Japanese government initiative called the 'Ubiquitous Element Strategy'. This focus issue also includes articles related to this strategy and to the associated topics of energy conversion, such as phosphors for high-efficiency lighting and photocatalysts for solar-energy harvesting. We hope that this focus issue will provide a timely overview of current trends and problems in ceramics science and

  5. Nano-Ceramic Coated Plastics

    NASA Technical Reports Server (NTRS)

    Cho, Junghyun

    2013-01-01

    Plastic products, due to their durability, safety, and low manufacturing cost, are now rapidly replacing cookware items traditionally made of glass and ceramics. Despite this trend, some still prefer relatively expensive and more fragile ceramic/glassware because plastics can deteriorate over time after exposure to foods, which can generate odors, bad appearance, and/or color change. Nano-ceramic coatings can eliminate these drawbacks while still retaining the advantages of the plastic, since the coating only alters the surface of the plastic. The surface coating adds functionality to the plastics such as self-cleaning and disinfectant capabilities that result from a photocatalytic effect of certain ceramic systems. These ceramic coatings can also provide non-stick surfaces and higher temperature capabilities for the base plastics without resorting to ceramic or glass materials. Titanium dioxide (TiO2) and zinc oxide (ZnO) are the candidates for a nano-ceramic coating to deposit on the plastics or plastic films used in cookware and kitchenware. Both are wide-bandgap semiconductors (3.0 to 3.2 eV for TiO2 and 3.2 to 3.3 eV for ZnO), so they exhibit a photocatalytic property under ultraviolet (UV) light. This will lead to decomposition of organic compounds. Decomposed products can be easily washed off by water, so the use of detergents will be minimal. High-crystalline film with large surface area for the reaction is essential to guarantee good photocatalytic performance of these oxides. Low-temperature processing (<100 C) is also a key to generating these ceramic coatings on the plastics. One possible way of processing nanoceramic coatings at low temperatures (< 90 C) is to take advantage of in-situ precipitated nanoparticles and nanostructures grown from aqueous solution. These nanostructures can be tailored to ceramic film formation and the subsequent microstructure development. In addition, the process provides environment- friendly processing because of the

  6. Spectrophotometric Determination of the Hole Concentration in the Superconductor YBa2Cu3O(sub 7-x)

    ERIC Educational Resources Information Center

    Hoppe, Jack I.; Malati, Mounir A.

    2005-01-01

    An experimental study of ceramic superconductors namely YBa2Cu3O(sub 7-x), which illustrates the use of spectrophotometry, based on the electronic spectra of complexes of Fe(II), Fe(III) and Cu(II) to better understand the stoichiometry of YBCO is described. The results from this experiment are in good agreement with those obtained by the…

  7. Performance of Ceramics in Severe Environments

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Fox, Dennis S.; Smialek, James L.; Deliacorte, Christopher; Lee, Kang N.

    2005-01-01

    Ceramics are generally stable to higher temperatures than most metals and alloys. Thus the development of high temperature structural ceramics has been an area of active research for many years. While the dream of a ceramic heat engine still faces many challenges, niche markets are developing for these materials at high temperatures. In these applications, ceramics are exposed not only to high temperatures but also aggressive gases and deposits. In this chapter we review the response of ceramic materials to these environments. We discuss corrosion mechanisms, the relative importance of a particular corrodent, and, where available, corrosion rates. Most of the available corrosion information is on silicon carbide (SIC) and silicon nitride (Si3N4) monolithic ceramics. These materials form a stable film of silica (SO2) in an oxidizing environment. We begin with a discussion of oxidation of these materials and proceed to the effects of other corrodents such as water vapor and salt deposits. We also discuss oxidation and corrosion of other ceramics: precurser derived ceramics, ceramic matrix composites (CMCs), ceramics which form oxide scales other than silica, and oxide ceramics. Many of the corrosion issues discussed can be mitigated with refractory oxide coatings and we discuss the current status of this active area of research. Ultimately, the concern of corrosion is loss of load bearing capability. We discuss the effects of corrosive environments on the strength of ceramics, both monolithic and composite. We conclude with a discussion of high temperature wear of ceramics, another important form of degradation at high temperatures.

  8. Glass Ceramic Formulation Data Package

    SciTech Connect

    Crum, Jarrod V.; Rodriguez, Carmen P.; McCloy, John S.; Vienna, John D.; Chung, Chul-Woo

    2012-06-17

    A glass ceramic waste form is being developed for treatment of secondary waste streams generated by aqueous reprocessing of commercial used nuclear fuel (Crum et al. 2012b). The waste stream contains a mixture of transition metals, alkali, alkaline earths, and lanthanides, several of which exceed the solubility limits of a single phase borosilicate glass (Crum et al. 2009; Caurant et al. 2007). A multi-phase glass ceramic waste form allows incorporation of insoluble components of the waste by designed crystallization into durable heat tolerant phases. The glass ceramic formulation and processing targets the formation of the following three stable crystalline phases: (1) powellite (XMoO4) where X can be (Ca, Sr, Ba, and/or Ln), (2) oxyapatite Yx,Z(10-x)Si6O26 where Y is alkaline earth, Z is Ln, and (3) lanthanide borosilicate (Ln5BSi2O13). These three phases incorporate the waste components that are above the solubility limit of a single-phase borosilicate glass. The glass ceramic is designed to be a single phase melt, just like a borosilicate glass, and then crystallize upon slow cooling to form the targeted phases. The slow cooling schedule is based on the centerline cooling profile of a 2 foot diameter canister such as the Hanford High-Level Waste canister. Up to this point, crucible testing has been used for glass ceramic development, with cold crucible induction melter (CCIM) targeted as the ultimate processing technology for the waste form. Idaho National Laboratory (INL) will conduct a scaled CCIM test in FY2012 with a glass ceramic to demonstrate the processing behavior. This Data Package documents the laboratory studies of the glass ceramic composition to support the CCIM test. Pacific Northwest National Laboratory (PNNL) measured melt viscosity, electrical conductivity, and crystallization behavior upon cooling to identify a processing window (temperature range) for melter operation and cooling profiles necessary to crystallize the targeted phases in the

  9. Tailored ceramics for laser applications

    NASA Astrophysics Data System (ADS)

    Hollingsworth, Joel Philip

    Transparent ceramics have many features that recommend them over single crystals for use as laser amplifiers. Some features, such as greater mechanical toughness and an absence of extended crystalline defects, are intrinsic to polycrystalline materials. Other advantages accrue from ceramic processing: ceramics sinter more rapidly than crystals grow from a melt, at lower temperatures. Ceramic processes are more readily scaled than Czochralski growth, facilitating larger apertures. Unlike a uniform melt, a ceramic green structure can have controlled concentration gradients, resulting in a multifunctional device upon sintering. Identifying diffusion mechanisms in a suitable host material and quantifying diffusion for a dopant with appropriate energy levels are key steps toward tailoring laser ceramics to the specifications of device designers. Toward that end, this study was the first to identify the mechanism and rate of Nd diffusion in YAG. Grain boundary diffusion was shown to dominate Nd transport under conditions relevant to laser ceramics fabrication. Based on a definition of grain boundary width as 1 A, this process occurs at a rate of DGB = 6.4 x 105 +/- 2.0 x 105 exp(-491 +/- 64 kJ/(mol K))m 2/s. Mechanism identification and the first published kinetics measurement were made possible by the introduction of a heat treatment method that isolates microstructural change from dopant diffusion: the concentration of grain boundaries was kept great enough to allow rapid diffusion, but low enough to limit the driving force for coarsening. Sintering of fine-grained and phase-pure precursor powder for 4 min at 1700 °C produced 0.8 mum grains; subsequent diffusion heat treatments at up to 1650 °C for up to 64 h caused negligible coarsening, while achieving diffusion distances of up to 23 mum.

  10. Microwave and transport studies of superconducting films of YBCO and fullerenes. Final technical report, 15 February 1993-31 August 1996

    SciTech Connect

    Dresselhaus, M.S.; Dresselhaus, G.

    1996-08-31

    During the 1995-96 year of the research program on `Microwave and Transport Studies of Superconducting Films of YBCO and Fullerenes,` the effort was focused on several projects. The main highlight was a collaborative study of the nonlinear microwave properties of superconducting YBa2Cu3O(7-x) (YBCO) which was carried out with researchers at Rome Labs and the MIT Lincoln Laboratory. During this year Nathan Belk completed his Ph.D. thesis entitled `Electronic Transport and Magnetic Properties of Disordered High-Tc Materials.` Joe Habib made significant progress with his study of microwave losses in individual Josephson junctions. A new graduate student, Chris Lehner, who is an Army Captain, joined the group on assignment from the US Army, and is working on the modeling of microwave losses in superconducting circuits. Continued progress was made with the use of femtosecond optics to study superconductivity and the associated phenomena in alkali metal doped C60 materials.

  11. Enhanced resonant soft X-ray scattering of YBa2Cu3O7-x (YBCO) 50 nm c-axis film on bi-crystalline substrates

    NASA Astrophysics Data System (ADS)

    Anavacerrada, Maria A.; Sahibudeen, Hizam; Acrivos, Juana V.; Kortright, Jeff B.

    2004-03-01

    The disorder induced by the grain boundary in Josepshon junctions fabricated with 50 nm YBCO films deposited on SrTiO3 bi-crystalline substrates [1] has been investigated by YBCO [001] enhanced resonant soft X-ray scattering. Spectra have been collected in the back scattering geometry near the O(K), Cu(L3,2) and Ba(M5,4) edges at three different positions across the grain boundary. The experiments were performed at the 6.3.1-Jeff B. Kortright station of the Advanced Light Source, LBNL. The strain fields of dislocations perturb the grain boundary local structure, mainly the YBCO oxygen sublattice leading to non-superconducting zones near the grain boundary. By comparison to published spectra near the Cu(L3,2) and Ba(M5,4) edges [2] the oxygen content 7-x is greater than 6.5 at any position in the film. The decrease in the relative intensity of the Cu(L3,2) main peaks in the spectra observed at positions close to the grain boundary suggest a high concentration of holes in the CuO2 layers in this region. Information on the oxygen composition across the grain boundary can be obtained by comparison of the O(K) edge spectra with data previously published on YBCO single crystal with different oxygen content [3]. [1] M. A. Navacerrada, M. L. Lucía and F. Sánchez Quesada, Europhys. Lett. 54, 387 (2001); [2] N. Nücker, E.Pellegrin, P. Schweiss, J. Fink, S. L. Molodtsov, C.T. Simmons, G. Kaindl, A. Erb and G. Müller Vogt, Phys. Rev. B 51, 8529 (1995); [3] J.- H. Guo, S. M. Butorin, N. Wassdahl and J. Nordgren, Phys. Rev. B 61, 9140 (2000) and references therein.

  12. Progress in fabrication of large magnetic sheilds by using extended YBCO thick films sprayed on stainless steel with the HVOF technique

    SciTech Connect

    Pavese, F.; Bergadano, E.; Ferri, D.

    1997-06-01

    Fabricating a full box-type magnetic shield, by spraying a thick film of commercial YBCO powder on stainless steel with the oxygen-fuel high-velocity technique (HVOF, also referred to as {open_quotes}continuous detonation spray{close_quotes} (CDS)), requires the solution of several specific problems since the design stage of the project. The design problems of this type of shield are examined and the results obtained in the early stages of the realization are discussed.

  13. Reliability of ceramics for heat engine applications

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The advantages and disadvantages associated with the use of monolithic ceramics in heat engines are discussed. The principle gaps in the state of understanding of ceramic material, failure origins, nondestructive tests as well as life prediction are included.

  14. Modeling projectile impact onto prestressed ceramic targets

    NASA Astrophysics Data System (ADS)

    Holmquist, T. J.; Johnson, G. R.

    2003-09-01

    This work presents computed results for the responses of ceramic targets, with and without prestress, subjected to projectile impact. Also presented is a computational technique to include prestress. Ceramic materials have been considered for armor applications for many years because of their high strength and low density. Many researchers have demonstrated that providing confinement enhances the ballistic performance of ceramic targets. More recently, prestressing the ceramic is being considered as an additional enhancement technique. This work investigates the effect of prestressing the ceramic for both thin and thick target configurations subjected to projectile impact. In all cases the targets with ceramic prestress provided enhanced ballistic performance. The computed results indicate that prestressed ceramic reduces and/or delays failure, resulting in improved ceramic performance and ballistic efficiency.

  15. Ceramic HEPA Filter Program

    SciTech Connect

    Mitchell, M A; Bergman, W; Haslam, J; Brown, E P; Sawyer, S; Beaulieu, R; Althouse, P; Meike, A

    2012-04-30

    Potential benefits of ceramic filters in nuclear facilities: (1) Short term benefit for DOE, NRC, and industry - (a) CalPoly HTTU provides unique testing capability to answer questions for DOE - High temperature testing of materials, components, filter, (b) Several DNFSB correspondences and presentations by DNFSB members have highlighted the need for HEPA filter R and D - DNFSB Recommendation 2009-2 highlighted a nuclear facility response to an evaluation basis earthquake followed by a fire (aka shake-n-bake) and CalPoly has capability for a shake-n-bake test; (2) Intermediate term benefit for DOE and industry - (a) Filtration for specialty applications, e.g., explosive applications at Nevada, (b) Spin-off technologies applicable to other commercial industries; and (3) Long term benefit for DOE, NRC, and industry - (a) Across industry, strong desire for better performance filter, (b) Engineering solution to safety problem will improve facility safety and decrease dependence on associated support systems, (c) Large potential life-cycle cost savings, and (d) Facilitates development and deployment of LLNL process innovations to allow continuous ventilation system operation during a fire.

  16. Ordered ceramic membranes

    SciTech Connect

    Anderson, M.A.; Hill, C.G. Jr.; Zeltner, W.A.

    1991-10-01

    Ceramic membranes have been formed from colloidal sols coated on porous clay supports. These supported membranes have been characterized in terms of their permeabilities and permselectivities to various aqueous test solutions. The thermal stabilities and pore structures of these membranes have been characterized by preparing unsupported membranes of the correpsonding material and performing N{sub 2} adsorption-desorption and X-ray diffraction studies on these membranes. To date, membranes have been prepared from a variety of oxides, including TiO{sub 2}, SiO{sub 2}, ZrO{sub 2}, and Al{sub 2}O{sub 3}, as well as Zr-, Fe-, and Nb-doped TiO{sub 2}. In many of these membranes pore diameters are less than 2 nm, while in others the pore diameters are between 3 and 5 nm. Procedures for fabricating porous clay supports with reproducible permeabilities for pure water are also discussed. 30 refs., 59 figs., 22 tabs.

  17. Thermally induced micromechanical stresses in ceramic/ceramic composites

    SciTech Connect

    Li, Zhuang; Bradt, R.C.

    1992-11-01

    The internal micromechanical stresses which develop in ceramic-ceramic composites as a consequence of temperature changes and thermoelastic property differences between the reinforcing and matrix phases are addressed by the Eshelby method. Results for two whisker reinforced ceramic matrix composites and for quartz particles in porcelain are discussed. It is concluded that the stresses which develop in the second phase reinforcing inclusions are quite substantial (GPa-levels) and may be highly anisotropic in character. These stresses are additive to the macroscopic thermal stresses from temperature gradients which are encountered during heating and cooling, and also to externally apphed mechanical stresses (loads). These micromechanical stresses are expected to be highly significant for thermal cycling fatigue and other failure processes.

  18. Microstructures and improved J c-H characteristics of Cl-containing YBCO thin films prepared by the fluorine-free MOD method

    NASA Astrophysics Data System (ADS)

    Motoki, Takanori; Shimoyama, Jun-ichi; Ogino, Hiraku; Kishio, Kohji; Roh, Jiyoung; Tohei, Tetsuya; Ikuhara, Yuichi; Horii, Shigeru; Doi, Toshiya; Honda, Genki; Nagaishi, Tatsuoki

    2016-01-01

    Undoped, Cl-doped, (Cl, Hf) co-doped and (Cl, Sn) co-doped YBa2Cu3O y (YBCO) thin films have been prepared by the fluorine-free metal-organic decomposition (FF-MOD) method on SrTiO3(100) single-crystalline substrates. Cross-sectional microstructures of these films were investigated in detail using scanning transmission electron microscopy (STEM). Rectangular-shaped oxychloride precipitates (Ba2Cu3O4Cl2) and fine particles (BaSnO3) were clearly observed in the (Cl, Sn) co-doped films. The magnetic angular dependence of the critical current density (J c-H-θ) of these films was evaluated. The existence of c-axis-correlated type pinning centers was suggested in Cl-containing YBCO films, whereas this type of pinning is not common in MOD-processed films. J c values were enhanced by Cl doping and further by (Cl, Sn) co-doping in all magnetic field directions at 77 K. This improved J c-H-θ property with c-axis-correlated pinning sites is the first report in FF-MOD-processed YBCO films.

  19. Correlation of local structure peculiarities and critical current density of 2G MOCVD YBCO tapes with BaZrO3 nanoinclusions

    NASA Astrophysics Data System (ADS)

    Menushenkov, A. P.; Ivanov, V. G.; Chepikov, V. N.; Nygaard, R. R.; Soldatenko, A. V.; Rudnev, I. A.; Osipov, M. A.; Mineev, N. A.; Kaul, A. R.; Mathon, O.; Monteseguro, V.

    2017-04-01

    We have studied the influence of BaZrO3 nanoinclusions on the local structure and critical current density of second-generation high temperature superconducting tapes based on YBa2Cu3O7‑δ (YBCO) films. The films were made by metal–organic chemical vapor deposition (MOCVD). The crystal and local structure of the materials under study were analysed by x-ray diffraction and x-ray absorption spectroscopy (EXAFS + XANES). We have found that, being added at MOCVD process, Zr forms BaZrO3 nanoinclusions in YBCO matrix. The distance between Zr and the neighboring atoms is shorter than that one in a bulk crystalline BaZrO3, so we conclude that the nanoinclusions are in compressed state. The incorporation of 5 mol% BaZrO3 minimizes the static disorder of Cu–O bonds and maximizes their stiffness in YBCO. We show that the local structure peculiarities correlate well with the observed critical current behavior and consider this to be additional evidence in favor of small amounts of BaZrO3 nanoinclusions as efficient pinning centers.

  20. Hydridosiloxanes as precursors to ceramic products

    DOEpatents

    Blum, Y.D.; Johnson, S.M.; Gusman, M.I.

    1997-06-03

    A method is provided for preparing ceramic precursors from hydridosiloxane starting materials and then pyrolyzing these precursors to give rise to silicious ceramic materials. Si-H bonds present in the hydridosiloxane starting materials are catalytically activated, and the activated hydrogen atoms may then be replaced with nonhydrogen substituents. These preceramic materials are pyrolyzed in a selected atmosphere to give the desired ceramic product. Ceramic products which may be prepared by this technique include silica, silicon oxynitride, silicon carbide, metal silicates, and mullite.

  1. Micromechanical Evaluation of Ceramic Matrix Composites

    DTIC Science & Technology

    1991-02-01

    Materials Sciences Corporation AD-A236 756 M.hM. 9 1 0513 IEIN HIfINU IIl- DTIC JUN 06 1991 MICROMECHANICAL EVALUATION OF S 0 CERAMIC MATRIX COMPOSITES C...Classification) \\() Micromechanical Evaluation of Ceramic Matrix Composites ) 12. PERSONAL AUTHOR(S) C-F. Yen, Z. Hashin, C. Laird, B.W. Rosen, Z. Wang 13a. TYPE...and strengthen the ceramic composites. In this task, various possibilities of crack propagation in unidirectional ceramic matrix composites under

  2. Organopolysiloxane Waterproofing Treatment for Porous Ceramics

    NASA Technical Reports Server (NTRS)

    Leiser, Daniel B. (Inventor); Cagliostro, Domenick E. (Inventor); Hsu, Ming-ta S. (Inventor); Chen, Timothy S. (Inventor)

    1998-01-01

    Rigid and flexible porous ceramics, including thermal insulation of a type used on space vehicles, are waterproofed by a treatment which comprises applying an aqueous solution of an organopolysiloxane water-proofing agent having reactive silanol groups to the surface of the ceramic and then heating the treated ceramic to form a waterproofed ceramic. The organopolysiloxane is formed by the hydrolysis and partial condensation of di- and trialkoxyfunctional alkylalkoxysilanes having 1-10 carbon atom hydrocarbyl groups.

  3. Baseline Industry Analysis, Advance Ceramics Industry

    DTIC Science & Technology

    1993-04-01

    Commerce , Department of Defense, and the National Critical Technologies Panel. Advanced Ceramics, which include ceramic matrix composites, are found in...ceramics and materials industry being identified as a National Critical Technology, Commerce Emerging Technology, and Defense Critical Technology.’ There is...total procurement cost in advanced systems, and as much as ten percent of the electronics portion of those weapons. Ceramic capacitors are almost as

  4. Process for strengthening silicon based ceramics

    DOEpatents

    Kim, Hyoun-Ee; Moorhead, A. J.

    1993-04-06

    A process for strengthening silicon based ceramic monolithic materials and omposite materials that contain silicon based ceramic reinforcing phases that requires that the ceramic be exposed to a wet hydrogen atmosphere at about 1400.degree. C. The process results in a dense, tightly adherent silicon containing oxide layer that heals, blunts , or otherwise negates the detrimental effect of strength limiting flaws on the surface of the ceramic body.

  5. Process for strengthening silicon based ceramics

    DOEpatents

    Kim, Hyoun-Ee; Moorhead, A. J.

    1993-01-01

    A process for strengthening silicon based ceramic monolithic materials and omposite materials that contain silicon based ceramic reinforcing phases that requires that the ceramic be exposed to a wet hydrogen atmosphere at about 1400.degree. C. The process results in a dense, tightly adherent silicon containing oxide layer that heals, blunts , or otherwise negates the detrimental effect of strength limiting flaws on the surface of the ceramic body.

  6. Emerging Ceramic-based Materials for Dentistry

    PubMed Central

    Denry, I.; Kelly, J.R.

    2014-01-01

    Our goal is to give an overview of a selection of emerging ceramics and issues for dental or biomedical applications, with emphasis on specific challenges associated with full-contour zirconia ceramics, and a brief synopsis on new machinable glass-ceramics and ceramic-based interpenetrating phase composites. Selected fabrication techniques relevant to dental or biomedical applications such as microwave sintering, spark plasma sintering, and additive manufacturing are also reviewed. Where appropriate, the authors have added their opinions and guidance. PMID:25274751

  7. Process for strengthening silicon based ceramics

    SciTech Connect

    Kim, Hyoun-Ee; Moorhead, A.J.

    1991-03-07

    A process for strengthening silicon based ceramic monolithic materials and composite materials that contain silicon based ceramic reinforcing phases that requires that the ceramic be exposed to a wet hydrogen atmosphere at about 1400{degrees}C. The process results in a dense, tightly adherent silicon containing oxide layer that heals, blunts, or otherwise negates the detrimental effect of strength limiting flaws on the surface of the ceramic body.

  8. Transient liquid phase ceramic bonding

    DOEpatents

    Glaeser, Andreas M.

    1994-01-01

    Ceramics are joined to themselves or to metals using a transient liquid phase method employing three layers, one of which is a refractory metal, ceramic or alloy. The refractory layer is placed between two metal layers, each of which has a lower melting point than the refractory layer. The three layers are pressed between the two articles to be bonded to form an assembly. The assembly is heated to a bonding temperature at which the refractory layer remains solid, but the two metal layers melt to form a liquid. The refractory layer reacts with the surrounding liquid and a single solid bonding layer is eventually formed. The layers may be designed to react completely with each other and form refractory intermetallic bonding layers. Impurities incorporated into the refractory metal may react with the metal layers to form refractory compounds. Another method for joining ceramic articles employs a ceramic interlayer sandwiched between two metal layers. In alternative embodiments, the metal layers may include sublayers. A method is also provided for joining two ceramic articles using a single interlayer. An alternate bonding method provides a refractory-metal oxide interlayer placed adjacent to a strong oxide former. Aluminum or aluminum alloys are joined together using metal interlayers.

  9. Ceramic tile expansion engine housing

    DOEpatents

    Myers, Blake

    1995-01-01

    An expandable ceramic tile housing for a high temperature engine is disclosed wherein each tile is independently supported in place in an interlocking matrix by retention mechanisms which mechanically couple the individual ceramic tiles to an outer metal support housing while maintaining thermal isolation of the metal housing from the ceramic tiles. The ceramic tiles are formed with either an octagonal front face portion and a square shank portion or a square front face portion with an octagonal shank portion. The length of the sides of the octagonal front face portion on one tile is equal to the length of the sides of the square front face portion of adjoining tiles to permit formation of an interlocking matrix. Fibrous ceramic sealing material may be placed between radial and tangential facing surfaces of adjacent tiles to limit radial gas flow therebetween. Labyrinth-sealed pressure-controlled compartments may be established between the tile housing and the outer metal support housing to control radial gas flow.

  10. Ceramic tile expansion engine housing

    DOEpatents

    Myers, B.

    1995-04-11

    An expandable ceramic tile housing for a high temperature engine is disclosed wherein each tile is independently supported in place in an interlocking matrix by retention mechanisms which mechanically couple the individual ceramic tiles to an outer metal support housing while maintaining thermal isolation of the metal housing from the ceramic tiles. The ceramic tiles are formed with either an octagonal front face portion and a square shank portion or a square front face portion with an octagonal shank portion. The length of the sides of the octagonal front face portion on one tile is equal to the length of the sides of the square front face portion of adjoining tiles to permit formation of an interlocking matrix. Fibrous ceramic sealing material may be placed between radial and tangential facing surfaces of adjacent tiles to limit radial gas flow there between. Labyrinth-sealed pressure-controlled compartments may be established between the tile housing and the outer metal support housing to control radial gas flow. 8 figures.

  11. Dynamic properties of ceramic materials

    SciTech Connect

    Grady, D.E.; Wise, J.L.

    1993-09-01

    Controlled impact methods have been employed to obtain dynamic response properties of armor materials. Experimental data have been obtained for high-strength ceramics. Continued analysis of time-resolved velocity interferometer measurements has produced systematic material-property data for Hugoniot and release response, initial and post-yield strength, pressure-induced phase transformation, and dynamic fracture strength. A new technique has been developed to measure hydrodynamic properties of ceramic through shock-wave experiments on metal-ceramic composites and data obtained for silicon carbide. Additional data on several titanium diboride ceramics and high-quality aluminum oxide ceramic have been acquired, and issues regarding the influence of microstructure on dynamic properties have emerged. Comparison of dynamic (Hugoniot elastic limit) strength and indentation hardness data has been performed and important correlations revealed. Innovative impact experiments on confined and unconfined alumina rods using axial and transverse VISAR diagnostics have been demonstrated which permit acquisition of multiaxial dynamic response data. Dynamic failure properties of a high-density aluminosilicate glass, similar in composition to the intergranular glassy phase of some aluminas, have been investigated with regard to yield, spall, and failure-wave propagation.

  12. Shock compression profiles in ceramics

    SciTech Connect

    Grady, D.E.; Moody, R.L.

    1996-03-01

    An investigation of the shock compression properties of high-strength ceramics has been performed using controlled planar impact techniques. In a typical experimental configuration, a ceramic target disc is held stationary, and it is struck by plates of either a similar ceramic or by plates of a well-characterized metal. All tests were performed using either a single-stage propellant gun or a two-stage light-gas gun. Particle velocity histories were measured with laser velocity interferometry (VISAR) at the interface between the back of the target ceramic and a calibrated VISAR window material. Peak impact stresses achieved in these experiments range from about 3 to 70 GPa. Ceramics tested under shock impact loading include: Al{sub 2}O{sub 3}, AlN, B{sub 4}C, SiC, Si{sub 3}N{sub 4}, TiB{sub 2}, WC and ZrO{sub 2}. This report compiles the VISAR wave profiles and experimental impact parameters within a database-useful for response model development, computational model validation studies, and independent assessment of the physics of dynamic deformation on high-strength, brittle solids.

  13. Crystalline ceramics: Waste forms for the disposal of weapons plutonium

    SciTech Connect

    Ewing, R.C.; Lutze, W.; Weber, W.J.

    1995-05-01

    At present, there are three seriously considered options for the disposition of excess weapons plutonium: (i) incorporation, partial burn-up and direct disposal of MOX-fuel; (ii) vitrification with defense waste and disposal as glass ``logs``; (iii) deep borehole disposal (National Academy of Sciences Report, 1994). The first two options provide a safeguard due to the high activity of fission products in the irradiated fuel and the defense waste. The latter option has only been examined in a preliminary manner, and the exact form of the plutonium has not been identified. In this paper, we review the potential for the immobilization of plutonium in highly durable crystalline ceramics apatite, pyrochlore, monazite and zircon. Based on available data, we propose zircon as the preferred crystalline ceramic for the permanent disposition of excess weapons plutonium.

  14. Characterization of interlaminar shear strength of ceramic matrix composites

    SciTech Connect

    Fang, N.J.J.; Tsuwei Chou . Dept. of Mechanical Engineering)

    1993-10-01

    The interlaminar shear strengths of three ceramic matrix composites have been characterized using a double-notch shear (DNS) test. The material systems investigated are plain woven C/SiC, plain woven SiC/SiC, and cross-plied SiC/calcium aluminosilicate-II. The use of the double-notch shear test for measuring the interlaminar shear strength of ceramic matrix composites is evaluated first. Numerical stress analyses are performed to investigate the effect of DNS specimen length, notch distance, and specimen supporting jig on the stress distribution in the expected fracture plane and the interlaminar shear strength. The numerical findings are then compared with an analytical model proposed elsewhere and correlated with the experimental results. The validity of this test technique has been established.

  15. Ceramics and ceramic matrix composites - Aerospace potential and status

    NASA Technical Reports Server (NTRS)

    Levine, Stanley R.

    1992-01-01

    Thermostructural ceramics and ceramic-matrix composites are attractive in numerous aerospace applications; the noncatastrophic fracture behavior and flaw-insensitivity of continuous fiber-reinforced CMCs renders them especially desirable. The present development status evaluation notes that, for most highly-loaded high-temperature applications, the requisite fiber-technology base is at present insufficient. In addition to materials processing techniques, the life prediction and NDE methods are immature and require a projection of 15-20 years for the maturity of CMC turbine rotors. More lightly loaded, moderate temperature aircraft engine applications are approaching maturity.

  16. Preparation of a dense, polycrystalline ceramic structure

    SciTech Connect

    Cooley, Jason; Chen, Ching-Fong; Alexander, David

    2010-12-07

    Ceramic nanopowder was sealed inside a metal container under a vacuum. The sealed evacuated container was forced through a severe deformation channel at an elevated temperature below the melting point of the ceramic nanopowder. The result was a dense nanocrystalline ceramic structure inside the metal container.

  17. Dense high temperature ceramic oxide superconductors

    DOEpatents

    Landingham, R.L.

    1993-10-12

    Dense superconducting ceramic oxide articles of manufacture and methods for producing these articles are described. Generally these articles are produced by first processing these superconducting oxides by ceramic processing techniques to optimize materials properties, followed by reestablishing the superconducting state in a desired portion of the ceramic oxide composite.

  18. Dense high temperature ceramic oxide superconductors

    DOEpatents

    Landingham, Richard L.

    1993-01-01

    Dense superconducting ceramic oxide articles of manufacture and methods for producing these articles are described. Generally these articles are produced by first processing these superconducting oxides by ceramic processing techniques to optimize materials properties, followed by reestablishing the superconducting state in a desired portion of the ceramic oxide composite.

  19. Uses of ceramics in microelectronics: A survey

    NASA Technical Reports Server (NTRS)

    Bratschun, W. R.; Mountvala, A. J.; Pincus, A. G.

    1971-01-01

    The properties and behavior of ceramic materials used in components for electronic circuitry are examined to appraise the present and future directions for microelectronics, and to suggest further product development, and how innovations may be useful in other technologies. Ceramic and glass insulators, resistors, capacitors, and the use of ceramics and glasses in microcircuitry are discussed along with technology transfer to nonaerospace uses.

  20. Instructional Resources. The Significance of Form: Ceramics.

    ERIC Educational Resources Information Center

    Zawatsky, Carole; And Others

    1989-01-01

    Presents four lesson plans designed to teach K-12 students about ceramics and the artists using the medium. Each lesson is centered around one ceramic piece: (1) "Wall Clock," by the Chantilly Porcelain Factory; (2) "Poppy Vase," by Adelaide Robineau; (3) "Laughing Eyes," by Pablo Picasso; and (4) "Ceramic Drum Jar," by Tsayutitsa. (GEA)