Science.gov

Sample records for high-temperature mossbauer spectroscopy

  1. Mossbauer Spectroscopy.

    ERIC Educational Resources Information Center

    Stevens, John G.; Bowen, Lawrence H.

    1980-01-01

    Reviews current research in Mossbauer spectroscopy, including instrumentation and experimental techniques, spectral analysis, catalysts and surfaces, environmental studies, medical applications and atmospheric air studies. Cites 346 references. (CS)

  2. Mossbauer spectroscopy with synchrotron radiation

    SciTech Connect

    Alp, E.E.; Mooney, T.M.; Toellner, T.; Sturhahn, W.

    1993-07-01

    The principles underlying observation of the Mossbauer effect with synchrotron radiation are explained. The current status of the field is reviewed, and prospects for dedicated experimental stations on third generation machines are discussed.

  3. Mossbauer spectroscopy of moon samples.

    PubMed

    Muir, A H; Housley, R M; Grant, R W; Abdel-Gawad, M; Blander, M

    1970-01-30

    Lunar bulk sample 10084,85 (< 1 mm size dust), and samples from rocks 10017,17 (fine grained, vesicular), 10046,17 (breccia), 10057,59 (fine grained, vesicular, top surface), 10057,60 (fine grained, vesicular, interior), and 10058,24 (medium grained, not vesicular) have been investigated by (57)Fe Mössbauer spectroscopy. Iron metal and the Fe(2+) minerals ilmenite, pyroxene, troilite, and iron containing glass have been identified. An iron line of sample 10084,85 (originally sealed in nitrogen) showed no significant intensity change when the sample was exposed to air. The antiferromagnetic transition in several lunar ilmenites at 57(0) +/- 2 degrees K corresponds to stoichiometric FeTiO,. Magneticallv separated 10057 showed troilite and somne metallic iron.

  4. Holdup Measures on an SRNL Mossbauer Spectroscopy Instrument

    SciTech Connect

    Dewberry, R.; Brown, T.; Salaymeh, S.

    2010-05-05

    Gamma-ray holdup measurements of a Mossbauer spectroscopy instrument are described and modeled. In the qualitative acquisitions obtained in a low background area of Savannah River National Laboratory, only Am-241 and Np-237 activity were observed. The Am-241 was known to be the instrumental activation source, while the Np-237 is clearly observed as a source of contamination internal to the instrument. The two sources of activity are modeled separately in two acquisition configurations using two separate modeling tools. The results agree well, demonstrating a content of (1980 {+-} 150) {mu}Ci Am-241 and (110 {+-} 50) {mu}Ci of Np-237.

  5. Mossbauer spectroscopy of iron in the Luna 20 regolith

    NASA Technical Reports Server (NTRS)

    Zemcik, T.; Raclavsky, K.

    1977-01-01

    Results of the Mossbauer effect measurements on Fe-57 in the average sample of the Luna 20 regolith, and their comparison with similar measurements of the Luna 16 samples are presented. Room temperature measurements of the nonmagnetic as well as magnetic components of the spectra were performed. By careful least-squares analysis, six quadrupole doublets in the inner parts of spectra were resolved. According to their splittings, they were interpreted as four types of iron in silicates (olivine, two inequivalent pyroxene sites, and a glassy fraction) and two types of nonmagnetic iron-titanium oxides (ilmenite and a spinel). Velocity-window measurements, were used to determine the average nickel content of (2.01 plus or minus 0.84) wt. %. These results are discussed in terms of distribution of iron among different phases. In comparison with the Luna 16 sample, the Luna 20 sample contains more olivine and less ilmenite as well as metal with a slightly higher nickel content.

  6. Multichannel euv spectroscopy of high temperature plasmas

    SciTech Connect

    Fonck, R.J.

    1983-11-01

    Spectroscopy of magnetically confined high temperature plasmas in the visible through x-ray spectral ranges deals primarily with the study of impurity line radiation or continuum radiation. Detailed knowledge of absolute intensities, temporal behavior, and spatial distributions of the emitted radiation is desired. As tokamak facilities become more complex, larger, and less accessible, there has been an increased emphasis on developing new instrumentation to provide such information in a minimum number of discharges. The availability of spatially-imaging detectors for use in the vacuum ultraviolet region (especially the intensified photodiode array) has generated the development of a variety of multichannel spectrometers for applications on tokamak facilities.

  7. IDENTIFICATION OF IRON PHASES IN BIOSOLIDS VIA MOSSBAUER SPECTROSCOPY

    EPA Science Inventory

    Continuous debate regarding inorganic and organic phases in biosolids as prominent sorbents of metals has yielded limited definitive data. We have demonstrated with X-ray absorption and X-ray fluorescence spectroscopies that metals in biosolids have a significant association with...

  8. Real-Time Noise Reduction for Mossbauer Spectroscopy through Online Implementation of a Modified Kalman Filter

    SciTech Connect

    Abrecht, David G.; Schwantes, Jon M.; Kukkadapu, Ravi K.; McDonald, Benjamin S.; Eiden, Gregory C.; Sweet, Lucas E.

    2015-02-01

    Spectrum-processing software that incorporates a gaussian smoothing kernel within the statistics of first-order Kalman filtration has been developed to provide cross-channel spectral noise reduction for increased real-time signal-to-noise ratios for Mossbauer spectroscopy. The filter was optimized for the breadth of the gaussian using the Mossbauer spectrum of natural iron foil, and comparisons between the peak broadening, signal-to-noise ratios, and shifts in the calculated hyperfine parameters are presented. The results of optimization give a maximum improvement in the signal-to-noise ratio of 51.1% over the unfiltered spectrum at a gaussian breadth of 27 channels, or 2.5% of the total spectrum width. The full-width half-maximum of the spectrum peaks showed an increase of 19.6% at this optimum point, indicating a relatively weak increase in the peak broadening relative to the signal enhancement, leading to an overall increase in the observable signal. Calculations of the hyperfine parameters showed no statistically significant deviations were introduced from the application of the filter, confirming the utility of this filter for spectroscopy applications.

  9. Study of anodic dissolution of Fe-Ru alloy with the aid of mossbauer spectroscopy

    SciTech Connect

    Khlystov, A.S.; Fasman, A.B.; Kil'dibekova, G.A.

    1986-01-10

    This paper uses Fe 57 Mossbauer spectroscopy, whereby iron compounds may be identified quantitatively and their composition and structure can be determined, for the study of the relationships of slime formation from Fe-Ru binary alloys. Both the products of dissolution and the composition and state of intermediate phases formed at various stages of anodic dissolution were studied simultaneously. It was found that the slimes formed both during chemical and during electrochemical destruction of ruthenium-iron alloys are finely dispersed systems of complex composition, analogous to those formed in the course of electrochemical dissolution of Ni-Ru alloys, which were found to contain oxide phases of ruthenium (by x-ray spectroscopy and ESCA) and of nickel (by x-ray phase analysis). The difference between the slime compositions is determined mainly by kinetic factors.

  10. Atomic absorption spectroscopy with high temperature flames.

    PubMed

    Willis, J B

    1968-07-01

    An account is given of the history of the development of high temperature flames for the atomic absorption measurement of metals forming refractory oxides. The principles governing the design of premix burners for such flames, and the relative merits of different types of nebulizer burner systems are described. After a brief account of the structure and emission characteristics of the premixed oxygen-acetylene and nitrous oxide-acetylene flames, the scope and limitations of the latter flame in chemical analysis are discussed.

  11. Vibrational spectroscopy in high temperature dense fluids

    SciTech Connect

    Moore, D.S.; Schmidt, S.C.

    1992-01-01

    Coherent anti-Stokes Raman spectroscopy (CARS) in conjunction with a two-stage light-gas gun has been used to obtain vibrational spectra of shock-compressed liquid N{sub 2}, O{sub 2}, CO, and their mixtures, as well as liquid N{sub 2}O. The experimental spectra are compared to spectra calculated using a semiclassical model for CARS intensities to obtain vibrational frequencies, peak Raman susceptibilities, and linewidths. The derived spectroscopic parameters suggest thermal equilibrium of the vibrational populations is established in less than a few nanoseconds after shock passage. Vibrational temperatures obtained are compared to those derived from equation-of-state calculations. The variation of the vibrational frequency shift at pressure with species concentration in mixtures is investigated.

  12. Identification of a green rust mineral in a reductomorphic soil by Mossbauer and Raman spectroscopies

    NASA Astrophysics Data System (ADS)

    Trolard, F.; Génin, J.-M. R.; Abdelmoula, M.; Bourrié, G.; Humbert, B.; Herbillon, A.

    1997-03-01

    Mössbauer and Raman spectroscopies are used to identify for the first time a green rust as a mineral in a reductomorphic soil from samples extracted in the forest of Fougères (Brittany-France). The Mossbauer spectrum displays two characteristic ferrous and ferric quadrupole doublets, the abundance ratio Fe(II)/Fe(Ill) of which is close to 1. Comparison with synthetic mixed valence Fe(II)Fe(HI) hydroxides supports the conclusion that the most probable formula is Fe2(OH)5, i.e., according to the pyroaurite-like crystal structure [Fe(n1Fe1III)(OH),]+o [OH] -. The microprobe Raman spectrum exhibits two bands at 518 and 427 cm-' as for synthetic green rusts. When exposed to the air, the new mineral goes rapidly from bluish-green to ochrous. The formula is compatible with the values of ionic activity products Q for equilibria between aqueous iron species and minerals obtained from soil waters, which suggests that this new mineral is likely to control the mobility of Fe in the environment.

  13. Mossbauer spectroscopy and X-ray diffraction of samples from the Santa Catharina iron meteorite

    NASA Technical Reports Server (NTRS)

    Roy-Poulsen, H.; Clarke, R. S., Jr.; Jensen, G. B.; Knudsen, J. M.; Larsen, L.; Roy-Poulsen, N. O.; Vistisen, L.

    1984-01-01

    Conversion electron Mossbauer spectroscopy (CEMS) of samples from the Santa Catharina iron meteorite shows the presence of the ordered iron-nickel phase with 50% Ni, tetrataenite, and of the paramagnetic iron-nickel phase with 25% Ni. The FeNi phase with 50% Ni amounts to 70% of the iron-nickel alloys. Futhermore, the CEM spectra show the presence of small peaks from one or more spinel compounds. These small peaks are more pronounced when regions near the rim of the samples are analyzed. The X-ray diffraction of different areas of the samples, both optically dark and optically light areas, shows the presence of a diffraction pattern from a single f.c.c. lattice with a lattice parameter of a=3.58A This means that the two different Fe-Ni phases seen in the CEMS analysis occupy the same lattice. The X-ray photographs also show the presence of super-structure reflections from the ordered FeNi phase, and that the orientation of the f.c.c. lattice is the same within the whole sample.

  14. Reflectance and Mossbauer spectroscopy of ferrihydrite-montmorillonite assemblages as Mars soil analog materials.

    PubMed

    Bishop, J L; Pieters, C M; Burns, R G

    1993-01-01

    Spectroscopic analyses show that Fe(3+)-doped smectites prepared in the laboratory exhibit important similarities to the soils on Mars. Ferrihydrite has been identified as the interlayer ferric component in Fe(3+)-doped smectites by a low quadrupole splitting and magnetic field strength of approximately 48 tesla in Mossbauer spectra measured at 4.2 K, as well as a crystal field transition at 0.92 micrometer. Ferrihydrite in these smectites explains features in the visible-near infrared region that resemble the energies and band strengths of features in reflectance spectra observed for several bright regions on Mars. Clay silicates have met resistance in the past as Mars soil analogs because terrestrial clay silicates exhibit prominent hydrous spectral features at 1.4, 1.9, and 2.2 micrometers; and these are observed weakly, if at all, in reflectance spectra of Mars. However, several mechanisms can weaken or compress these features, including desiccation under low-humidity conditions. The hydration properties of the interlayer cations also effect band strengths, such that a ferrihydrite-bearing smectite in the Martian environment would exhibit a 1.9 micrometers H2O absorption that is even weaker than the 2.2 micrometers structural OH absorption. Mixing experiments demonstrate that infrared spectral features of clays can be significantly suppressed and that the reflectance can be significantly darkened by mixing with only a few percent of a strongly absorbing opaque material. Therefore, the absolute reflectance of a soil on Mars may be disproportionately sensitive to a minor component. For this reason, the shape and position of spectral features and the chemical composition of potential analogs are of utmost importance in assessing the composition of the soil on Mars. Given the remarkable similarity between visible-infrared reflectance spectra of soils in bright regions on Mars and Fe(3+)-doped montmorillonites, coupled with recent observations of smectites in SNC

  15. Reflectance and Mossbauer spectroscopy of ferrihydrite-montmorillonite assemblages as Mars soil analog materials

    NASA Technical Reports Server (NTRS)

    Bishop, J. L.; Pieters, C. M.; Burns, R. G.; Chang, S. (Principal Investigator)

    1993-01-01

    Spectroscopic analyses show that Fe(3+)-doped smectites prepared in the laboratory exhibit important similarities to the soils on Mars. Ferrihydrite has been identified as the interlayer ferric component in Fe(3+)-doped smectites by a low quadrupole splitting and magnetic field strength of approximately 48 tesla in Mossbauer spectra measured at 4.2 K, as well as a crystal field transition at 0.92 micrometer. Ferrihydrite in these smectites explains features in the visible-near infrared region that resemble the energies and band strengths of features in reflectance spectra observed for several bright regions on Mars. Clay silicates have met resistance in the past as Mars soil analogs because terrestrial clay silicates exhibit prominent hydrous spectral features at 1.4, 1.9, and 2.2 micrometers; and these are observed weakly, if at all, in reflectance spectra of Mars. However, several mechanisms can weaken or compress these features, including desiccation under low-humidity conditions. The hydration properties of the interlayer cations also effect band strengths, such that a ferrihydrite-bearing smectite in the Martian environment would exhibit a 1.9 micrometers H2O absorption that is even weaker than the 2.2 micrometers structural OH absorption. Mixing experiments demonstrate that infrared spectral features of clays can be significantly suppressed and that the reflectance can be significantly darkened by mixing with only a few percent of a strongly absorbing opaque material. Therefore, the absolute reflectance of a soil on Mars may be disproportionately sensitive to a minor component. For this reason, the shape and position of spectral features and the chemical composition of potential analogs are of utmost importance in assessing the composition of the soil on Mars. Given the remarkable similarity between visible-infrared reflectance spectra of soils in bright regions on Mars and Fe(3+)-doped montmorillonites, coupled with recent observations of smectites in SNC

  16. Mossbauer Studies of Some Iron

    NASA Astrophysics Data System (ADS)

    Boyd, Darwin Lee

    ^{57}Fe Mossbauer spectroscopy was used to investigate several iron(III) spin crossover systems as well as a cold cholesteric liquid crystal. Tris thioseleno- and tris diselenocarbamates were found to be similar to their corresponding tris monothio and tris dithio complexes, showing increasing magnetic moment with increasing isomer shift and decreasing magnetic moment with increasing quadrupole splitting. These observations indicate that the tris thioseleno- and tris diselenocarbamates are, like their dithio analogs, spin crossover systems. Several mixed ligand thioseleno complexes were also studied and found to be similar to the corresponding dithio complexes. A possible trihydrate of Fe(S_2CN(CH _2CH_2OH) _2)_3 was investigated. Repeated attempts to reproduce a recently published four line Mossbauer spectrum for the trihydrate failed. It was concluded that the published methods actually result in the anhydrous complex. Heating of this complex in accordance with the published methods to produce the anhydrous complex resulted in decomposition. Anhydrous preparations of Fe(S_2CN(CH _2CH_2OH) _2)_3 when recrystallized from methanol without heating produced four line Mossbauer spectra at low temperatures. The temperature dependencies of the isomer shift, quadrupole splitting, and peak area indicate that, in this case, the interconversion rate between the two spin states has slowed to below the inverse of the Mossbauer time scale. This slowing is believed to be caused by partial solvation by small, nonstoichiometric, quantities of methanol. Cholesterol-2-(2-ethoxy ethoxy) ethyl carbonate was investigated via Mossbauer spectroscopy by dissolving into it 0.16wt% ^{57 }Fe enriched 1,1^' -diacetylferrocene. A glass transition temperature of 177 K and a Mossbauer Debye temperature of 32.7 K were measured. An increase in the average half width of the resonance lines above the glass transition temperature indicates the onset of diffusion in the supercooled liquid. A lack of

  17. Spectroscopy and kinetics of combustion gases at high temperatures

    SciTech Connect

    Hanson, R.K.; Bowman, C.T.

    1993-12-01

    This program involves two complementary activities: (1) development and application of cw ring dye laser absorption methods for sensitive detection of radical species and measurement of fundamental spectroscopic parameters at high temperatures; and (2) shock tube studies of reaction kinetics relevant to combustion. Species currently under investigation in the spectroscopic portion of the research include NO and CH{sub 3}; this has necessitated the continued operated at wavelengths in the range 210-230 nm. Shock tube studies of reaction kinetics currently are focussed on reactions involving CH{sub 3} radicals.

  18. High-temperature spectroscopy for nuclear waste applications

    SciTech Connect

    Grant, P.M.; Robouch, P.; Torres, R.A.; Silva, R.J.

    1991-10-01

    Instrumentation has been developed to perform uv-vis-nir absorbance measurements remotely and at elevated temperatures and pressures. Fiber-optic spectroscopy permits the interrogation of radioactive species within a glovebox enclosure at temperatures ranging from ambient to >100{degree}C. Spectral shifts as a function of metal- ligand coordination are used to compute thermodynamic free energies of reaction by matrix regression analysis. Pr{sup 3+} serves as a convenient analog for trivalent actinides without attendant radioactivity hazards, and recent results obtained from 20{degree}--95{degree}C with the Pr-acetate complexation system are presented. Preliminary experimentation on Am(3) hydrolysis is also described. 16 refs., 1 tab.

  19. Distinguishing Na, K, and H3O+ Jarosite and Alunite on Mars using VNIR, Emittance and Mossbauer Spectroscopy on the MER and Mars Express/OMEGA Missions

    NASA Astrophysics Data System (ADS)

    Bishop, J. L.; Rothstein, Y.; Dyar, M. D.; Lane, M. D.; Klima, R. L.; Brophy, G. P.

    2005-12-01

    Jarosite has been identified in layered outcrops in Meridiani by the MER Mossbauer spectrometer [Klingelhofer, et al., 2004] and may be present elsewhere on Mars. We are studying VNIR, emittance and Mossbauer spectroscopy of a suite of synthetic and natural samples of jarosite and alunite from the Brophy collection [e.g. Brophy and Sheridan, 1965]. The characteristic NIR overtones and combination bands in this group differ not only depending on the trivalent cation (e.g. Al for alunite and Fe for jarosite), but also depending on the type of monovalent cation (typically K, Na and/or H3O). The VNIR spectrum of K-jarosite exhibits an OH stretching band at 1.47 um, an OH stretch + 2 bend combination doublet at 1.849 and 1.864 um, plus an OH stretch + bend combination triplet at 2.215, 2.265, and 2.300 um and additional OH and SO4 combination features near 2.40, 2.46, 2.50, 2.60 and 2.62 um. H3O- and Na-jarosite spectra exhibit broader features and the doublet is less resolvable. The spectrum of Na-jarosite contains a band at 1.48 um, a broad asymmetric band near 1.85 um and a triplet near 2.235, 2.275, and 2.310 um, plus additional features near 2.42, 2.47, 2.52, 2.62 and 2.64 um. Band assignments for jarosite and alunite spectra are from Bishop and Murad [2005]. We are in the process of comparing these spectra with the mid-IR and Mossbauer spectra of this jarosite group sample suite in order to perform coordinated analyses for this sulfate group on Mars using the MER and Mars Express datasets. References: Bishop, J. L., and E. Murad (2005), The visible and infrared spectral properties of jarosite and alunite, Am. Miner., 90, 1100-1107. Brophy, G. P., and M. F. Sheridan (1965), Sulfate studies IV: The jarosite-natrojarosite-hydronium jarosite solid solution series, Am. Miner., 50, 1595-1607. Klingelhofer, G., et al. (2004), Jarosite and hematite at Meridiani Planum from Opportunity's Mossbauer spectrometer, Science, 306, 1740-1745.

  20. Synthesis, structure, magnetic susceptibility and Mossbauer and Raman spectroscopies of the new oxyphosphate Fe{sub 0.50}TiO(PO{sub 4})

    SciTech Connect

    Benmokhtar, S. . E-mail: s.benmokhtar@univh2m.ac.ma; El Jazouli, A.; Chaminade, J.P.; Gravereau, P.; Wattiaux, A.; Fournes, L.; Grenier, J.C.; Waal, D.

    2006-12-15

    A new iron titanyl oxyphosphate Fe{sub 0.50}TiO(PO{sub 4}) was synthesized by both solid-state reaction and Cu{sup 2+}-Fe{sup 2+} ion exchange method. The material was then characterized by X-ray diffraction, Mossbauer spectroscopy, magnetic susceptibility measurements and Raman spectroscopy. The crystal structure of the compound was refined, using X-ray powder diffraction data, by Rietveld profile method; it crytallizes in the monoclinic system, space group P2{sub 1}/c (No.14), with a=7.4039(3)A, b=7.3838(3)A, c=7.4083(3)A, {beta}=120.36{sup o}(1), V=349.44(2)A{sup 3} and Z=4. The volume of the title compound is comparable to those of the M{sub 0.50}{sup II}TiO(PO{sub 4}) series, where M{sup II}=Mg, Co, Ni and Zn. The framework is built up from [TiO{sub 6}] octahedra and [PO{sub 4}] tetrahedra. [TiO{sub 6}] octahedra are linked together by corners and form infinite chains along the c-axis. Ti atoms are displaced from the center of octahedral units showing an alternating short distance (1.73A) and a long one (2.22A). These chains are linked together by [PO{sub 4}] tetrahedra. Fe{sup 2+} cations occupy a triangle-based antiprism sharing two faces with two [TiO{sub 6}] octahedra. Mossbauer and magnetic measurements show the existence of iron only in divalent state, located exclusively in octahedral sites with high spin confition (t{sub 2g}{sup 4}e{sub g}{sup 2}). Raman study confirms the existence of Ti-O-Ti chains.

  1. Understanding electronegative effects in core-level electron spectroscopies; application to the high temperature superconductors

    NASA Astrophysics Data System (ADS)

    Ramaker, David E.

    1989-12-01

    The nature of the core level reflected in x ray photoelectron spectroscopy, Auger electron spectrosocopy, and x ray absorption near edge structure is considered. An understanding of the effects of anion and cation electronegativity on spectra for the transition metal halides is obtained. This knowledge is applied to understand similar spectra for the high temperature superconductors.

  2. Characterization of catalysts by Mossbauer spectroscopy: An application to the study of Fischer-Tropsch, hydrotreating and super Claus catalysts

    NASA Astrophysics Data System (ADS)

    van der Kraan, A. M.; Boellaard, E.; Crajé, M. W. J.

    1993-04-01

    Mössbauer spectroscopy is an excellent in-situ technique for the identification of phases present in catalysts. Applied to metallic iron catalysts used in the Fischer-Tropsch reaction it reveals a detailed picture of the carburization process and provides insight into the relation between the properties of the catalytic material and its activity. The influence of a support and the effect of alloying iron with an (in)active metal on the catalytic performance is discussed for Fe, CuFe and NiFe systems. In addition, Mössbauer spectroscopy is used for the identification of "Co-sulfide" species present in sulfided Co and CoMo catalysts applied in one of the largest chemical processes in the world, the hydrotreatment of crude oil. A structural model is proposed. Finally, the contribution of Mössbauer spectroscopic studies to the development of a new catalyst for cleaning of Claus tail gas via selective oxidation of hydrogen sulfide to elemental sulfur is discussed.

  3. Trace species detection: Spectroscopy and molecular energy transfer at high temperature

    SciTech Connect

    Gray, J.A.

    1993-12-01

    Monitoring the concentration of trace species such as atomic and molecular free radicals is essential in forming predictive models of combustion processes. LIF-based techniques have the necessary sensitivity for concentration and temperature measurements but have limited accuracy due to collisional quenching in combustion applications. The goal of this program is to use spectroscopic and kinetic measurements to quantify nonradiative and collisional effects on LIF signals and to develop new background-free alternatives to LIF. The authors have measured the natural linewidth of several OH A-X (3,0) rotational transitions to determine predissociation lifetimes in the upper state, which were presumed to be short compared to quenching lifetimes, and as a result, quantitative predictions about the applicability of predissociation fluorescence methods at high pressures are made. The authors are investigating collisional energy transfer in the A-state of NO. Quenching rates which enable direct corrections to NO LIF quantum yields at high temperature were calculations. These quenching rates are now being used in studies of turbulence/chemistry interactions. The authors have measured the electric dipole moment {mu} of excited-state NO using Stark quantum-beat spectroscopy. {mu} is an essential input to a harpoon model which predicts quenching efficiencies for NO (A) by a variety of combustion-related species. The authors are developing new coherent multiphoton techniques for measurements of atomic hydrogen concentration in laboratory flames to avoid the quenching problems associated with previous multiphoton LIF schemes.

  4. Universal features in the photoemission spectroscopy of high-temperature superconductors.

    PubMed

    Zhao, Junjing; Chatterjee, Utpal; Ai, Dingfei; Hinks, David G; Zheng, Hong; Gu, G D; Castellan, John-Paul; Rosenkranz, Stephan; Claus, Helmut; Norman, Michael R; Randeria, Mohit; Campuzano, Juan Carlos

    2013-10-29

    The energy gap for electronic excitations is one of the most important characteristics of the superconducting state, as it directly reflects the pairing of electrons. In the copper-oxide high-temperature superconductors (HTSCs), a strongly anisotropic energy gap, which vanishes along high-symmetry directions, is a clear manifestation of the d-wave symmetry of the pairing. There is, however, a dramatic change in the form of the gap anisotropy with reduced carrier concentration (underdoping). Although the vanishing of the gap along the diagonal to the square Cu-O bond directions is robust, the doping dependence of the large gap along the Cu-O directions suggests that its origin might be different from pairing. It is thus tempting to associate the large gap with a second-order parameter distinct from superconductivity. We use angle-resolved photoemission spectroscopy to show that the two-gap behavior and the destruction of well-defined electronic excitations are not universal features of HTSCs, and depend sensitively on how the underdoped materials are prepared. Depending on cation substitution, underdoped samples either show two-gap behavior or not. In contrast, many other characteristics of HTSCs, such as the dome-like dependence of on doping, long-lived excitations along the diagonals to the Cu-O bonds, and an energy gap at the Brillouin zone boundary that decreases monotonically with doping while persisting above (the pseudogap), are present in all samples, irrespective of whether they exhibit two-gap behavior or not. Our results imply that universal aspects of high- superconductivity are relatively insensitive to differences in the electronic states along the Cu-O bond directions. PMID:24101464

  5. Universal features in the photoemission spectroscopy of high-temperature superconductors

    PubMed Central

    Zhao, Junjing; Chatterjee, Utpal; Ai, Dingfei; Hinks, David G.; Zheng, Hong; Gu, G. D.; Castellan, John-Paul; Rosenkranz, Stephan; Claus, Helmut; Norman, Michael R.; Randeria, Mohit; Campuzano, Juan Carlos

    2013-01-01

    The energy gap for electronic excitations is one of the most important characteristics of the superconducting state, as it directly reflects the pairing of electrons. In the copper–oxide high-temperature superconductors (HTSCs), a strongly anisotropic energy gap, which vanishes along high-symmetry directions, is a clear manifestation of the d-wave symmetry of the pairing. There is, however, a dramatic change in the form of the gap anisotropy with reduced carrier concentration (underdoping). Although the vanishing of the gap along the diagonal to the square Cu–O bond directions is robust, the doping dependence of the large gap along the Cu–O directions suggests that its origin might be different from pairing. It is thus tempting to associate the large gap with a second-order parameter distinct from superconductivity. We use angle-resolved photoemission spectroscopy to show that the two-gap behavior and the destruction of well-defined electronic excitations are not universal features of HTSCs, and depend sensitively on how the underdoped materials are prepared. Depending on cation substitution, underdoped samples either show two-gap behavior or not. In contrast, many other characteristics of HTSCs, such as the dome-like dependence of on doping, long-lived excitations along the diagonals to the Cu–O bonds, and an energy gap at the Brillouin zone boundary that decreases monotonically with doping while persisting above (the pseudogap), are present in all samples, irrespective of whether they exhibit two-gap behavior or not. Our results imply that universal aspects of high- superconductivity are relatively insensitive to differences in the electronic states along the Cu–O bond directions. PMID:24101464

  6. MIMOS II on MER One Year of Mossbauer Spectroscopy on the Surface of Mars: From Jarosite at Meridiani Planum to Goethite at Gusev Crater

    NASA Technical Reports Server (NTRS)

    Klingelhoefer, G.; Rodionov, D. S.; Morris, R. V.; Schroeder, C.; deSouza, P. A.; Ming, D. W.; Yen, A. S.; Bernhardt, B.; Renz, F.; Fleischer, I.

    2005-01-01

    The miniaturized Mossbauer (MB) spectrometer MIMOS II [1] is part of the Athena payload of NASA s twin Mars Exploration Rovers "Spirit" (MER-A) and "Opportunity" (MER-B). It determines the Fe-bearing mineralogy of Martian soils and rocks at the Rovers respective landing sites, Gusev crater and Meridiani Planum. Both spectrometers performed successfully during first year of operation. Total integration time is about 49 days for MERA (79 samples) and 34 days for MER-B (85 samples). For curiosity it might be interesting to mention that the total odometry of the oscillating part of the MB drive exceeds 35 km for both rovers.

  7. High temperature and high resolution uv photoelectron spectroscopy using supersonic molecular beams

    SciTech Connect

    Wang, Lai-Sheng; Reutt-Robey, J.E.; Niu, B.; Lee, Y.T.; Shirley, D.A.; Maryland Univ., College Park, MD . Dept. of Chemistry and Biochemistry; Lawrence Berkeley Lab., CA )

    1989-07-01

    A high temperature molecular beam source with electron bombardment heating has been built for high resolution photoelectron spectroscopic studies of high temperature species and clusters. This source has the advantages of: producing an intense, continuous, seeded molecular beam, eliminating the interference of the heating mechanism from the photoelectron measurement. Coupling the source with our hemispherical electron energy analyzer, we can obtain very high resolution HeI{alpha} (584{angstrom}) photoelectron spectra of high temperature species. Vibrationally-resolved photoelectron spectra of PbSe, As{sub 2}, As{sub 4}, and ZnCl{sub 2} are shown to demonstrate the performance of the new source. 25 refs., 8 figs., 1 tab.

  8. Alkaline Earth Core Level Photoemission Spectroscopy of High-Temperature Superconductors

    NASA Technical Reports Server (NTRS)

    Vasquez, R.

    1993-01-01

    This paper examines photoemission measurements of the alkaline Earth core levels of high-temperature superconductors and related materials, models that seek to explain the large negative shifts observed relative to the corresponding alkaline Earth metals, and the effect of lattice site disorder on the core level spectra and the presence or absence of intrinsic surface peaks.

  9. High temperature radiance spectroscopy measurements of solid and liquid uranium and plutonium carbides

    NASA Astrophysics Data System (ADS)

    Manara, D.; De Bruycker, F.; Boboridis, K.; Tougait, O.; Eloirdi, R.; Malki, M.

    2012-07-01

    In this work, an experimental study of the radiance of liquid and solid uranium and plutonium carbides at wavelengths 550 nm ⩽ λ ⩽ 920 nm is reported. A fast multi-channel spectro-pyrometer has been employed for the radiance measurements of samples heated up to and beyond their melting point by laser irradiation. The melting temperature of uranium monocarbide, soundly established at 2780 K, has been taken as a radiance reference. Based on it, a wavelength-dependence has been obtained for the high-temperature spectral emissivity of some uranium carbides (1 ⩽ C/U ⩽ 2). Similarly, the peritectic temperature of plutonium monocarbide (1900 K) has been used as a reference for plutonium monocarbide and sesquicarbide. The present spectral emissivities of solid uranium and plutonium carbides are close to 0.5 at 650 nm, in agreement with previous literature values. However, their high temperature behaviour, values in the liquid, and carbon-content and wavelength dependencies in the visible-near infrared range have been determined here for the first time. Liquid uranium carbide seems to interact with electromagnetic radiation in a more metallic way than does the solid, whereas a similar effect has not been observed for plutonium carbides. The current emissivity values have also been used to convert the measured radiance spectra into real temperature, and thus perform a thermal analysis of the laser heated samples. Some high-temperature phase boundaries in the systems U-C and Pu-C are shortly discussed on the basis of the current results.

  10. In-plane tunneling spectroscopy of the high temperature superconductor, Bi-2212

    NASA Astrophysics Data System (ADS)

    Kane, Jeffrey William

    A novel technique for tunneling into the a-b plane of the layered cuprate (copper-oxide) superconductors is described and applied to the study of the in-plane tunneling spectra of the high temperature superconductor Bisb2Srsb2CaCusb2Osb8 (Bi-2212). This technique involves using a home-built low-temperature scanning tunneling microscope to form mechanical tunneling junctions with well-prepared edges of single crystals. Our research group has pioneered the use of these cross-junctions, and the results presented in this dissertation constitute the first systematic investigation employing this technique. Using this cross-junction tunneling technique, the superconducting energy gap has been measured along various directions within the a-b plane of Bi-2212. The results show unambiguously that the in-plane energy gap is highly anisotropic. The measured energy gap Deltasbp-p is largest along the a-axis direction, with Deltasbp-p≈ 36 meV and decreases gradually with Deltasbp-p≈ 20 meV along the direction 45sp° from the a-axis. The anisotropy pattern is found to have a four-fold symmetry. Using these results, an angular mapping of the in-plane gap anisotropy is presented and compared to theoretical predictions as well as results from other experiments. Effects due to the gap anisotropy on the tunneling spectra are also discussed. In another set or experiments, the effects of Pb doping on the tunneling spectra of Bi-2212 were studied. Doping Bi-2212 with Pb causes a partial substitution of the Bi atoms between the conducting Cu-Osb2 planes, and modifies some of the electronic and structural properties of the material. In this study it was found that while Pb doping decreases Tsbc profoundly, it has a minimal effect on the in-plane energy gap, leading to a significant increase in the reduced gap, 2Delta /ksb{B}Tsb{c}. This result is consistent with other studies of the effects of in-plane dopants, but is the first evidence of such an effect attributable to defects

  11. High Temperature Line Lists For Carbon Monoxide From Microwave Discharge Spectroscopy

    NASA Astrophysics Data System (ADS)

    Rezaie, Farnood; Figueiredo, P.; Arnold, J.; Peale, R.

    2011-05-01

    In gas giant exoplanets that orbit close to their parent stars, known as hot Jupiters, carbon is thought to be sequestered primarily in carbon monoxide and methane. The relative CO and CH4 abundances inform us about temperature and pressure conditions and also about mixing by global winds driven by intense but asymmetric heating for these tidally-locked bodies. Emission spectra collected during secondary eclipses, as the hot Jupiter passes behind its parent star, in principle allows a determination of the CO:CH4 concentration ratio. Since hot Jupiters exist at temperatures of order 1000 K, accurate model atmospheres require high temperature line lists for relevant molecules, for which existing data bases are apparently incomplete. Here we present high temperature emission spectra of CO. The spectra were obtained using a microwave discharge apparatus where the source of CO was carbon dioxide that dissociates under microwave heating. The pressure inside the discharge tube was of order 1 Torr and the microwave power applied to the cavity was 70 W. Emission exited the discharge tube via a ZnSe window and entered through a NaCl window the emission port of the evacuated Fourier spectrometer. The spectrum was measured in the range 1800-2400 cm-1 at a resolution of 0.1 cm-1 using a KBr beamsplitter and a 77 K InSb detector. Vibrational transitions V(1->0) centered at 2147 cm-1 and V(2->1) at 2120 cm-1 were clearly identified. From the J values for maximum intensity lines within the rotational fine structure we obtain a temperature estimate of 1400 K, which is comparable to the atmospheric conditions of hot-Jupiters. Obtained line lists are compared with existing information in the HITRAN database.

  12. A high-temperature, ambient-pressure ultra-dry operando reactor cell for Fourier-transform infrared spectroscopy.

    PubMed

    Köck, Eva-Maria; Kogler, Michaela; Pramsoler, Reinhold; Klötzer, Bernhard; Penner, Simon

    2014-08-01

    The construction of a newly designed high-temperature, high-pressure FT-IR reaction cell for ultra-dry in situ and operando operation is reported. The reaction cell itself as well as the sample holder is fully made of quartz glass, with no hot metal or ceramic parts in the vicinity of the high-temperature zone. Special emphasis was put on chemically absolute water-free and inert experimental conditions, which includes reaction cell and gas-feeding lines. Operation and spectroscopy up to 1273 K is possible, as well as pressures up to ambient conditions. The reaction cell exhibits a very easy and variable construction and can be adjusted to any available FT-IR spectrometer. Its particular strength lies in its possibility to access and study samples under very demanding experimental conditions. This includes studies at very high temperatures, e.g., for solid-oxide fuel cell research or studies where the water content of the reaction mixtures must be exactly adjusted. The latter includes all adsorption studies on oxide surfaces, where the hydroxylation degree is of paramount importance. The capability of the reaction cell will be demonstrated for two selected examples where information and in due course a correlation to other methods can only be achieved using the presented setup.

  13. A high-temperature, ambient-pressure ultra-dry operando reactor cell for Fourier-transform infrared spectroscopy

    SciTech Connect

    Köck, Eva-Maria; Kogler, Michaela; Pramsoler, Reinhold; Klötzer, Bernhard; Penner, Simon

    2014-08-15

    The construction of a newly designed high-temperature, high-pressure FT-IR reaction cell for ultra-dry in situ and operando operation is reported. The reaction cell itself as well as the sample holder is fully made of quartz glass, with no hot metal or ceramic parts in the vicinity of the high-temperature zone. Special emphasis was put on chemically absolute water-free and inert experimental conditions, which includes reaction cell and gas-feeding lines. Operation and spectroscopy up to 1273 K is possible, as well as pressures up to ambient conditions. The reaction cell exhibits a very easy and variable construction and can be adjusted to any available FT-IR spectrometer. Its particular strength lies in its possibility to access and study samples under very demanding experimental conditions. This includes studies at very high temperatures, e.g., for solid-oxide fuel cell research or studies where the water content of the reaction mixtures must be exactly adjusted. The latter includes all adsorption studies on oxide surfaces, where the hydroxylation degree is of paramount importance. The capability of the reaction cell will be demonstrated for two selected examples where information and in due course a correlation to other methods can only be achieved using the presented setup.

  14. Vibration analysis utilizing Mossbauer effect

    NASA Technical Reports Server (NTRS)

    Roughton, N. A.

    1967-01-01

    Measuring instrument analyzes mechanical vibrations in transducers at amplitudes in the range of a few to 100 angstroms. This instrument utilizes the Mossbauer effect, the phenomenon of the recoil-free emission and resonant absorption of nuclear gamma rays in solids.

  15. Applying X-ray Imaging Crystal Spectroscopy for Use as a High Temperature Plasma Diagnostic.

    PubMed

    Cao, Norman M; Mier Valdivia, Andrés M; Rice, John E

    2016-01-01

    X-ray spectra provide a wealth of information on high temperature plasmas; for example electron temperature and density can be inferred from line intensity ratios. By using a Johann spectrometer viewing the plasma, it is possible to construct profiles of plasma parameters such as density, temperature, and velocity with good spatial and time resolution. However, benchmarking atomic code modeling of X-ray spectra obtained from well-diagnosed laboratory plasmas is important to justify use of such spectra to determine plasma parameters when other independent diagnostics are not available. This manuscript presents the operation of the High Resolution X-ray Crystal Imaging Spectrometer with Spatial Resolution (HIREXSR), a high wavelength resolution spatially imaging X-ray spectrometer used to view hydrogen- and helium-like ions of medium atomic number elements in a tokamak plasma. In addition, this manuscript covers a laser blow-off system that can introduce such ions to the plasma with precise timing to allow for perturbative studies of transport in the plasma. PMID:27585305

  16. Fluorescence spectroscopy of kerosene vapour at high temperatures and pressures: potential for gas turbines measurements

    NASA Astrophysics Data System (ADS)

    Orain, M.; Baranger, P.; Ledier, C.; Apeloig, J.; Grisch, F.

    2014-09-01

    Laser-induced fluorescence spectroscopy of kerosene vapour was performed in a heated test cell operating between 450 and 900 K, at pressure from 0.1 to 3.0 MPa, for oxygen molar fraction between 0 and 21 %, with different laser excitation wavelengths (248, 266, 282 and 308 nm). Results show that, depending on the laser excitation scheme, kerosene fluorescence spectrum exhibits one or two fluorescence bands in the UV-visible range (attributed to aromatics naturally present in kerosene fuel). Fluorescence intensity of these bands decreases with increasing temperature, pressure and oxygen molar fraction. Different imaging strategies were derived from spectroscopic findings to simultaneously measure temperature and equivalence ratio fields in kerosene/air sprays, or flame structure and fuel spatial distribution in kerosene/air aeronautical combustors, by means of planar laser-induced fluorescence on kerosene vapour (K-PLIF).

  17. Local structural studies of oriented high-temperature superconducting cuprates by polarized XAFS spectroscopy

    NASA Astrophysics Data System (ADS)

    Haskel, Daniel

    1998-07-01

    Doping (Sr,Ba) in Lasb{2-x}(Sr,Ba)sb{x}CuOsb4 induces high Tsb{c} superconductivity in addition to profound changes in structural, magnetic and normal state electronic properties. The purpose of this thesis is to investigate the structural characteristics accompanying this doping by performing orientation dependent x-ray absorption fine structure (XAFS) measurements on magnetically aligned powders. This type of measurements allowed obtaining critical information at the La/(Sr,Ba) site previously unavailable, as detailed below. The measurements show that hole carriers introduced with Sr are polaronic in nature as evident from the two site configuration found for the O(2) apical neighboring Sr and the lack of temperature dependence in the O(2) distribution, which indicates that the hole states associated with each site are not discrete but rather broader than ksb{B}T up to T = 300K. There is a good theoretical argument suggesting each O(2) site is associated with holes being doped into O(1) 2psb{x,y}-Cu 3dsb{xsp2-ysp2} in-plane and O(2) 2psb{z}-Cu 3dsb{3zsp2-rsp2} out-of-plane electronic bands resulting in two different Jahn-Teller distortions of the CuOsb6 octahedra neighboring Sr, where the doped holes are peaked. Based on this argument, the predominance of out-of-plane character for the doped holes, as evidenced from the concentration dependence of the relative population of O(2) sites, would imply that theories of high Tsb{c} relying only on in-plane character of the doped holes are not complete in describing the properties of these cuprates. Our measurements showed that all structural phase transitions in Lasb{2-x}(Sr,Ba)sb{x}CuOsb4 have a significant order-disorder component, as opposed to the purely displacive models found in crystallographic studies. The CuOsb6 octahedra are locally tilted in the high-doping, high-temperature phases but fail to order over long range resulting in the average structures of the crystallographic studies. A critical parameter in

  18. The high-temperature elastic moduli of polycrystalline PbTe measured by resonant ultrasound spectroscopy

    SciTech Connect

    Ren, Fei; Case, Eldon D; Sootsman, Joseph; Kanatzidis, Mercouri G.; Kong, Huijun; Uher, Ctirad; Lara-Curzio, Edgar; Trejo, Rosa M

    2008-01-01

    The thermoelectric material PbTe has been used in a wide variety of power generator applications. However, there is limited mechanical property data available for PbTe for temperatures above room temperature. This paper reports dynamic elastic moduli measured via resonant ultrasound spectroscopy on undoped and PbI2-doped polycrystalline PbTe between room temperature and 773 K; in addition, the room temperature carrier concentration was measured by a Hall effect experiment. The Young s modulus and shear modulus of PbTe decreased linearly with temperature above room temperature, while the Poisson s ratio exhibited either monotonic increase or decrease with temperature. The Young s modulus and shear modulus values obtained during heating and cooling agreed to within 1%. The dynamic elastic moduli data obtained in this study compared well in general with literature data. The difference observed between the current study and other literature studies is explained in terms of the carrier concentration effect on elastic moduli.

  19. Impedance spectroscopy on ceramic materials at high temperatures, considering stray fields and electromagnetic noise.

    PubMed

    Müller, T M; Meinhardt, J; Raether, F

    2013-01-01

    Impedance spectroscopy of many ceramics is a challenge due to their high electrical resistance. Small disturbances can significantly alter the measuring results. In the present paper, it is shown how impedance measurements can be performed in an electromagnetically noisy ac furnace, using consequent Faraday shielding of the sample and the electrical connections. As example, the conductivity data of alumina was measured between room temperature and 1000 °C and compared to literature data. In addition, a correction method for the calculation of permittivity was developed to consider the stray fields in the sample-electrode setup. The distribution of the electrical field was simulated by finite element (FE) methods for different sample geometries and electrode arrangements. The deviations from the behavior of an ideal plate capacitor follow a linear trend and are in the order of 5% to 20% for an experimentally reasonable range of sample thicknesses. To check the theoretical results experimentally, alumina samples of varying thickness were measured. The customary calculation of permittivity leads to a clear trend with sample thickness, whereas the correction from the FE-simulation produces almost constant values of the relative permittivity.

  20. Impedance spectroscopy on ceramic materials at high temperatures, considering stray fields and electromagnetic noise

    NASA Astrophysics Data System (ADS)

    Müller, T. M.; Meinhardt, J.; Raether, F.

    2013-01-01

    Impedance spectroscopy of many ceramics is a challenge due to their high electrical resistance. Small disturbances can significantly alter the measuring results. In the present paper, it is shown how impedance measurements can be performed in an electromagnetically noisy ac furnace, using consequent Faraday shielding of the sample and the electrical connections. As example, the conductivity data of alumina was measured between room temperature and 1000 °C and compared to literature data. In addition, a correction method for the calculation of permittivity was developed to consider the stray fields in the sample-electrode setup. The distribution of the electrical field was simulated by finite element (FE) methods for different sample geometries and electrode arrangements. The deviations from the behavior of an ideal plate capacitor follow a linear trend and are in the order of 5% to 20% for an experimentally reasonable range of sample thicknesses. To check the theoretical results experimentally, alumina samples of varying thickness were measured. The customary calculation of permittivity leads to a clear trend with sample thickness, whereas the correction from the FE-simulation produces almost constant values of the relative permittivity.

  1. Vapor phase tri-methyl-indium seeding system suitable for high temperature spectroscopy and thermometry

    NASA Astrophysics Data System (ADS)

    Whiddon, R.; Zhou, B.; Borggren, J.; Aldén, M.; Li, Z. S.

    2015-09-01

    Tri-methyl-indium (TMI) is used as an indium transport molecule to introduce indium atoms to reactive hot gas flows/combustion environments for spectroscopic diagnostics. A seeding system was constructed to allow the addition of an inert TMI laden carrier gas into an air/fuel mixture burning consequently on a burner. The amount of the seeded TMI in the carrier gas can be readily varied by controlling the vapor pressure through the temperature of the container. The seeding process was calibrated using the fluorescent emission intensity from the indium 62S1/2 → 52P1/2 and 62S1/2 → 52P3/2 transitions as a function of the calculated TMI seeding concentration over a range of 2-45 ppm. The response was found to be linear over the range 3-22.5 ppm; at concentrations above 25 ppm there is a loss of linearity attributable to self-absorption or loss of saturation of TMI vapor pressure in the carrier gas flow. When TMI was introduced into a post-combustion environment via an inert carrier gas, molecular transition from InH and InOH radicals were observed in the flame emission spectrum. Combined laser-induced fluorescence and absorption spectroscopy were applied to detect indium atoms in the TMI seeded flame and the measured atomic indium concentration was found to be at the ppm level. This method of seeding organometallic vapor like TMI to a reactive gas flow demonstrates the feasibility for quantitative spectroscopic investigations that may be applicable in various fields, e.g., chemical vapor deposition applications or temperature measurement in flames with two-line atomic fluorescence.

  2. Vapor phase tri-methyl-indium seeding system suitable for high temperature spectroscopy and thermometry.

    PubMed

    Whiddon, R; Zhou, B; Borggren, J; Aldén, M; Li, Z S

    2015-09-01

    Tri-methyl-indium (TMI) is used as an indium transport molecule to introduce indium atoms to reactive hot gas flows/combustion environments for spectroscopic diagnostics. A seeding system was constructed to allow the addition of an inert TMI laden carrier gas into an air/fuel mixture burning consequently on a burner. The amount of the seeded TMI in the carrier gas can be readily varied by controlling the vapor pressure through the temperature of the container. The seeding process was calibrated using the fluorescent emission intensity from the indium 6(2)S1/2 → 5(2)P1/2 and 6(2)S1/2 → 5(2)P3/2 transitions as a function of the calculated TMI seeding concentration over a range of 2-45 ppm. The response was found to be linear over the range 3-22.5 ppm; at concentrations above 25 ppm there is a loss of linearity attributable to self-absorption or loss of saturation of TMI vapor pressure in the carrier gas flow. When TMI was introduced into a post-combustion environment via an inert carrier gas, molecular transition from InH and InOH radicals were observed in the flame emission spectrum. Combined laser-induced fluorescence and absorption spectroscopy were applied to detect indium atoms in the TMI seeded flame and the measured atomic indium concentration was found to be at the ppm level. This method of seeding organometallic vapor like TMI to a reactive gas flow demonstrates the feasibility for quantitative spectroscopic investigations that may be applicable in various fields, e.g., chemical vapor deposition applications or temperature measurement in flames with two-line atomic fluorescence. PMID:26429429

  3. Vapor phase tri-methyl-indium seeding system suitable for high temperature spectroscopy and thermometry

    SciTech Connect

    Whiddon, R.; Zhou, B.; Borggren, J.; Aldén, M.; Li, Z. S.

    2015-09-15

    Tri-methyl-indium (TMI) is used as an indium transport molecule to introduce indium atoms to reactive hot gas flows/combustion environments for spectroscopic diagnostics. A seeding system was constructed to allow the addition of an inert TMI laden carrier gas into an air/fuel mixture burning consequently on a burner. The amount of the seeded TMI in the carrier gas can be readily varied by controlling the vapor pressure through the temperature of the container. The seeding process was calibrated using the fluorescent emission intensity from the indium 6{sup 2}S{sub 1/2} → 5{sup 2}P{sub 1/2} and 6{sup 2}S{sub 1/2} → 5{sup 2}P{sub 3/2} transitions as a function of the calculated TMI seeding concentration over a range of 2–45 ppm. The response was found to be linear over the range 3–22.5 ppm; at concentrations above 25 ppm there is a loss of linearity attributable to self-absorption or loss of saturation of TMI vapor pressure in the carrier gas flow. When TMI was introduced into a post-combustion environment via an inert carrier gas, molecular transition from InH and InOH radicals were observed in the flame emission spectrum. Combined laser-induced fluorescence and absorption spectroscopy were applied to detect indium atoms in the TMI seeded flame and the measured atomic indium concentration was found to be at the ppm level. This method of seeding organometallic vapor like TMI to a reactive gas flow demonstrates the feasibility for quantitative spectroscopic investigations that may be applicable in various fields, e.g., chemical vapor deposition applications or temperature measurement in flames with two-line atomic fluorescence.

  4. Auger electron spectroscopy study of oxidation of a PdCr alloy used for high-temperature sensors

    NASA Technical Reports Server (NTRS)

    Boyd, Darwin L.; Zeller, Mary V.; Vargas-Aburto, Carlos

    1993-01-01

    A Pd-13 wt. percent Cr solid solution is a promising high-temperature strain gage alloy. In bulk form it has a number of properties that are desirable in a resistance strain gage material, such as a linear electrical resistance versus temperature curve to 1000 C and stable electrical resistance in air at 1000 C. However, unprotected fine wire gages fabricated from this alloy perform well only to 600 C. At higher temperatures severe oxidation degrades their electrical performance. In this work Auger electron spectroscopy was used to study the oxidation chemistry of the alloy wires and ribbons. Results indicate that the oxidation is caused by a complex mechanism that is not yet fully understood. As expected, during oxidation, a layer of chromium oxide is formed. This layer, however, forms beneath a layer of metallic palladium. The results of this study have increased the understanding of the oxidation mechanism of Pd-13 wt. percent Cr.

  5. Crystal structure, magnetic susceptibility and Mossbauer spectroscopy of the mixed-valence iron phosphate Na{sub 1/2}Cu{sub 4/3}Fe{sub 2}(PO{sub 4}){sub 3}

    SciTech Connect

    Hidouri, Mourad; Lajmi, Besma; Wattiaux, Alain; Fournes, Leopold; Darriet, Jacques; Amara, Mongi B. . E-mail: Mongi.Benamara@fsm.rnu.tn

    2006-06-15

    Single crystals of a new mixed-valent iron phosphate Na{sub 1/2}Cu{sub 4/3}Fe{sub 2}(PO{sub 4}){sub 3} have been synthesized by a flux method and structurally characterized from X-ray diffraction data. Crystal data: space group P1-bar ; a=6.2882(1)A; b=8.0459(1)A; c=9.3255(1)A; {alpha}=105.881(1){sup o}; {beta}=107.202(1){sup o}; {gamma}=101.467(1){sup o}; Z=2; R{sub 1}=0.03; wR{sub 2}=0.093. The three-dimensional structure was found to be closely related to that of the well known Howardevansite structural type. It results from infinite chains of CuO{sub 5} and FeO{sub 6} polyhedra, joined together by (Cu,-bar )O{sub 6} octahedra and PO{sub 4} tetrahedra by corner-sharing. The large cavities in framework are occupied by Na{sup +} ions. The magnetic susceptibility study revealed an antiferromagnetic behavior with Neel temperature of approximately 40K. The Mossbauer spectroscopy confirmed the presence of iron in both +2 and +3 oxidation states.

  6. In Site Analysis of a High Temperature Cure Reaction in Real Time Using Modulated Fiber-Optic FT-Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Cooper, John; Aust, Jeffrey F.; Wise, Kent L.; Jensen, Brian J.

    1999-01-01

    The vibrational spectrum of a high temperature (330 C) polymerization reaction was successfully monitored in real time using a modulated fiber-optic FT-Raman spectrometer. A phenylethynyl terminated monomer was cured, and spectral evidence for two different reaction products was acquired. The products are a conjugated polyene chain and a cyclized trimer. This is the first report describing the use of FT-Raman spectroscopy to monitor a high temperature (greater than 250 C) reaction in real time.

  7. Error Analysis of Remotely-Acquired Mossbauer Spectra

    NASA Technical Reports Server (NTRS)

    Schaefer, Martha W.; Dyar, M. Darby; Agresti, David G.; Schaefer, Bradley E.

    2005-01-01

    On the Mars Exploration Rovers, Mossbauer spectroscopy has recently been called upon to assist in the task of mineral identification, a job for which it is rarely used in terrestrial studies. For example, Mossbauer data were used to support the presence of olivine in Martian soil at Gusev and jarosite in the outcrop at Meridiani. The strength (and uniqueness) of these interpretations lies in the assumption that peak positions can be determined with high degrees of both accuracy and precision. We summarize here what we believe to be the major sources of error associated with peak positions in remotely-acquired spectra, and speculate on their magnitudes. Our discussion here is largely qualitative because necessary background information on MER calibration sources, geometries, etc., have not yet been released to the PDS; we anticipate that a more quantitative discussion can be presented by March 2005.

  8. Letter - X-ray diffraction and Mossbauer spectroscopy of Fe{sup 3+}-bearing Mg-silicate post-perovskite at 128-138 GPa.

    SciTech Connect

    Catalli, K.; Shim, S. H.; Prakapenka, V. B.; Zhao, J.; Sturhahn, W.

    2010-01-01

    The effect of ferric iron on the properties of Mg-silicate post-perovskite (PPv) were studied up to 138 GPa using synchrotron X-ray diffraction and Moessbauer spectroscopy. Our diffraction measurements revealed that the incorporation of Fe{sup 3+} has virtually no effect on the volume of PPv, in contrast to Fe{sup 2+}, which increases the volume. Therefore, incorporation of Fe{sup 3+} increases the density of PPv much more effectively than Fe{sup 2+}. Moessbauer spectroscopy suggests that Fe{sup 3+} enters PPv through charge-coupled substitution and is high spin in the bipolar prismatic site and low spin in the octahedral site (i.e., mixed spin state). Our results may have important implications for the gravitational stability of lower-mantle heterogeneities.

  9. [In situ experimental study of phase transition of calcite by Raman spectroscopy at high temperature and high pressure].

    PubMed

    Liu, Chuan-jiang; Zheng, Hai-fei

    2012-02-01

    The phase transitions of calcite at high temperature and high pressure were investigated by using hydrothermal diamond anvil cell combined with Raman spectroscopy. The result showed that the Raman peak of 155 cm(-1) disappeared, the peak of 1 087 cm(-1) splited into 1083 and 1 090 cm(-1) peaks and the peak of 282 cm(-1) abruptly reduced to 231 cm(-1) at ambient temperature when the system pressure increased to 1 666 and 2 127 MPa respectively, which proved that calcite transformed to calcite-II and calcite-III. In the heating process at the initial pressure of 2 761 MPa and below 171 degrees C, there was no change in Raman characteristic peaks of calcite-III. As the temperature increased to 171 degrees C, the color of calcite crystal became opaque completely and the symmetric stretching vibration peak of 1 087 cm(-1), in-plane bending vibration peak of 713 cm(-1) and lattice vibration peaks of 155 and 282 cm(-1) began to mutate, showing that the calcite-III transformed to a new phase of calcium carbonate at the moment. When the temperature dropped to room temperature, this new phase remained stable all along. It also indicated that the process of phase transformation from calcite to the new phase of calcium carbonate was irreversible. The equation of phase transition between calcite-III and new phase of calcium carbonate can be determined by P(MPa) = 9.09T x (degrees C) +1 880. The slopes of the Raman peak (v1 087) of symmetrical stretching vibration depending on pressure and temperature are dv/dP = 5.1 (cm(-1) x GPa(-1)) and dv/dT = -0.055 3(cm(-1) x degrees C(-1)), respectively. PMID:22512172

  10. A Mossbauer investigation of iron-rich terrestrial hydrothermal vent systems: lessons for Mars exploration.

    PubMed

    Wade, M L; Agresti, D G; Wdowiak, T J; Armendarez, L P; Farmer, J D

    1999-04-25

    Hydrothermal spring systems may well have been present on early Mars and could have served as a habitat for primitive life. The integrated instrument suite of the Athena Rover has, as a component on the robotic arm, a Mossbauer spectrometer. In the context of future Mars exploration we present results of Mossbauer analysis of a suite of samples from an iron-rich thermal spring in the Chocolate Pots area of Yellowstone National Park (YNP) and from Obsidian Pool (YNP) and Manitou Springs, Colorado. We have found that Mossbauer spectroscopy can discriminate among the iron-bearing minerals in our samples. Those near the vent and on the surface are identified as ferrihydrite, an amorphous ferric mineraloid. Subsurface samples, collected from cores, which are likely to have undergone inorganic and/or biologically mediated alteration (diagenesis), exhibit spectral signatures that include nontronite (a smectite clay), hematite (alpha-Fe2O3), small-particle/nanophase goethite (alpha-FeOOH), and siderite (FeCO3). We find for iron minerals that Mossbauer spectroscopy is at least as efficient in identification as X-ray diffraction. This observation is important from an exploration standpoint. As a planetary surface instrument, Mossbauer spectroscopy can yield high-quality spectral data without sample preparation (backscatter mode). We have also used field emission scanning electron microscopy (FESEM), in conjunction with energy-dispersive X ray (EDX) fluorescence spectroscopy, to characterize the microbiological component of surface sinters and the relation between the microbiological and the mineralogical framework. Evidence is presented that the minerals found in these deposits can have multi-billion-year residence times and thus may have survived their possible production in a putative early Martian hot spring up to the present day. Examples include the nanophase property and the Mossbauer signature for siderite, which has been identified in a 2.09-billion-year old hematite

  11. A Mossbauer investigation of iron-rich terrestrial hydrothermal vent systems: lessons for Mars exploration

    NASA Technical Reports Server (NTRS)

    Wade, M. L.; Agresti, D. G.; Wdowiak, T. J.; Armendarez, L. P.; Farmer, J. D.

    1999-01-01

    Hydrothermal spring systems may well have been present on early Mars and could have served as a habitat for primitive life. The integrated instrument suite of the Athena Rover has, as a component on the robotic arm, a Mossbauer spectrometer. In the context of future Mars exploration we present results of Mossbauer analysis of a suite of samples from an iron-rich thermal spring in the Chocolate Pots area of Yellowstone National Park (YNP) and from Obsidian Pool (YNP) and Manitou Springs, Colorado. We have found that Mossbauer spectroscopy can discriminate among the iron-bearing minerals in our samples. Those near the vent and on the surface are identified as ferrihydrite, an amorphous ferric mineraloid. Subsurface samples, collected from cores, which are likely to have undergone inorganic and/or biologically mediated alteration (diagenesis), exhibit spectral signatures that include nontronite (a smectite clay), hematite (alpha-Fe2O3), small-particle/nanophase goethite (alpha-FeOOH), and siderite (FeCO3). We find for iron minerals that Mossbauer spectroscopy is at least as efficient in identification as X-ray diffraction. This observation is important from an exploration standpoint. As a planetary surface instrument, Mossbauer spectroscopy can yield high-quality spectral data without sample preparation (backscatter mode). We have also used field emission scanning electron microscopy (FESEM), in conjunction with energy-dispersive X ray (EDX) fluorescence spectroscopy, to characterize the microbiological component of surface sinters and the relation between the microbiological and the mineralogical framework. Evidence is presented that the minerals found in these deposits can have multi-billion-year residence times and thus may have survived their possible production in a putative early Martian hot spring up to the present day. Examples include the nanophase property and the Mossbauer signature for siderite, which has been identified in a 2.09-billion-year old hematite

  12. A Mossbauer investigation of iron-rich terrestrial hydrothermal vent systems: lessons for Mars exploration.

    PubMed

    Wade, M L; Agresti, D G; Wdowiak, T J; Armendarez, L P; Farmer, J D

    1999-04-25

    Hydrothermal spring systems may well have been present on early Mars and could have served as a habitat for primitive life. The integrated instrument suite of the Athena Rover has, as a component on the robotic arm, a Mossbauer spectrometer. In the context of future Mars exploration we present results of Mossbauer analysis of a suite of samples from an iron-rich thermal spring in the Chocolate Pots area of Yellowstone National Park (YNP) and from Obsidian Pool (YNP) and Manitou Springs, Colorado. We have found that Mossbauer spectroscopy can discriminate among the iron-bearing minerals in our samples. Those near the vent and on the surface are identified as ferrihydrite, an amorphous ferric mineraloid. Subsurface samples, collected from cores, which are likely to have undergone inorganic and/or biologically mediated alteration (diagenesis), exhibit spectral signatures that include nontronite (a smectite clay), hematite (alpha-Fe2O3), small-particle/nanophase goethite (alpha-FeOOH), and siderite (FeCO3). We find for iron minerals that Mossbauer spectroscopy is at least as efficient in identification as X-ray diffraction. This observation is important from an exploration standpoint. As a planetary surface instrument, Mossbauer spectroscopy can yield high-quality spectral data without sample preparation (backscatter mode). We have also used field emission scanning electron microscopy (FESEM), in conjunction with energy-dispersive X ray (EDX) fluorescence spectroscopy, to characterize the microbiological component of surface sinters and the relation between the microbiological and the mineralogical framework. Evidence is presented that the minerals found in these deposits can have multi-billion-year residence times and thus may have survived their possible production in a putative early Martian hot spring up to the present day. Examples include the nanophase property and the Mossbauer signature for siderite, which has been identified in a 2.09-billion-year old hematite

  13. In Situ Analysis of a High-Temperature Cure Reaction in Real Time Using Modulated Fiber-Optic FT-Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Aust, Jeffrey F.; Cooper, John B.; Wise, Kent L.; Jensen, Brian J.

    1999-01-01

    The vibrational spectrum of a high-temperature (330 C) polymerization reaction was successfully monitored in real time with the use of a modulated fiber-optic Fourier transform (FT)-Raman spectrometer. A phenylethynyl-terminated monomer was cured, and spectral evidence for two different reaction products was acquired. The products are a conjugated polyene chain and a cyclized trimer. This is the first report describing the use of FT-Raman spectroscopy to monitor a high temperature (greater than 250 C) reaction in real time.

  14. Feasibility Study of Using High-Temperature Raman Spectroscopy for On-Line Monitoring and Product Control of the Glass Vitrification Process

    SciTech Connect

    Windisch, C.F. Jr.; Piepel, G.F.; Li, H.; Elliott, M.L.; Su, Y.

    1999-01-04

    A pulse-gating Raman spectroscopy setup was developed in this project. The setup was capable of performing in-situ high-temperature Raman measurements for glasses at temperatures as high as 1412 C. In the literature, high-temperature Raman measurements have only been performed on thin films of glass to minimize black-body radiation effects. The pulse-gating Raman setup allows making high-temperature measurements for bulk melts while effectively minimizing black-body radiation effects. A good correlation was found between certain Raman characteristic parameters and glass melt temperature for sodium silicate glasses measured in this project. Comparisons were made between the high-temperature Raman data from this study and literature data. The results suggest that an optimization of the pulse-gating Raman setup is necessary to further improve data quality (i.e., to obtain data with a higher signal-to-noise ratio). An W confocal Raman microspectrometer with continuous wave laser excitation using a 325 nm excitation line was evaluated selectively using a transparent silicate glass ad a deep-colored high-level waste glass in a bulk quantity. The data were successfully collected at temperatures as high as approximately 1500 C. The results demonstrated that the UV excitation line can be used for high-temperature Raman measurements of molten glasses without black-body radiation interference from the melt for both transparent and deep-color glasses. Further studies are needed to select the best laser system that can be used to develop high-temperature Raman glass databases.

  15. Revised Mossbauer Calibration for Fe3+/FeT of XANES Basalt Standards: Implications for MORB

    NASA Astrophysics Data System (ADS)

    Hirschmann, M. M.; Zhang, H.; Cottrell, E.

    2015-12-01

    Among techniques for determining Fe3+/FeT of natural glasses, XANES affords high precision, spatial resolution, and sample throughput and consequently has become widely used. However, because XANES determinations depend on standardization against materials of known Fe3+/FeT, they are only as accurate as the methods used for calibration. In many cases, calibration is performed with Mossbauer spectroscopy. Accurate determination of Fe3+/FeT by Mossbauer spectroscopy is the subject of a long-standing controversy, in part owing to debate as to the influence of recoilless fraction on the area ratios of room temperature (RT) Mossbauer absorption doublets associated with paramagnetic Fe2+ and Fe3+ in silicate glasses. Recoilless fraction effects for glasses are comparatively subtle, and so characterization efforts have not always produced statistically resolvable effects, in part because glasses produce broadened line shapes that degrade analytical precision, but both theoretical considerations of bond strengths and abundant evidence from minerals demonstrate that RT Mossbauer analyses will overestimate Fe3+/FeTof Fe-bearing silicates. Cottrell & Kelley (2011) used the basalt XANES calibration of Cottrell et al. (2009) to show that the average Fe3+/FeT of MORB glasses is close to 0.16, but this calibration depends chiefly on RT Mossbauer spectra of a suite of standard glasses. New cryogenic (10 K) Mossbauer spectra of these same glasses suggests a correction factor, C, of 1.1, where [Fe3+/FeT(corrected)]=[Fe3+/FeT (RT)]/([Fe3+/FeT (RT)]+C(1-[Fe3+/FeT(RT)]). If this correction is applied to the XANES data, the median of MORB glasses is ~0.15. Because recoilless fractions are not exactly unity even at 10 K, this correction represents a minimum; however the 10 K data are in good agreement with Fe3+/FeT predicted for the Mossbauer standards by the wet-chemistry-based model of Kress and Carmichael (1991) based on the synthesis fO2. The precision of XANES for the determination

  16. The combination of laser micro-boring and high resolution α-spectroscopy for the analysis of α-emitting isotopes in irradiated high-temperature-reactor fuel

    NASA Astrophysics Data System (ADS)

    Helmbold, M.; Allelein, H. J.; Koch, H. R.

    1980-02-01

    A new method for the determination of α-emitting isotopes in irradiated high-temperature-reactor fuel has been developed. By use of a laser micro-boring system it is possible to prepare extremely thin α-spectroscopy samples out of any part of the fuel with a spatial resolution of about 10 μm. The measurement of the samples with a silicon barrier detector yields α-spectra of high resolution, allowing the determination of the content of most of the heavy metal isotopes. The method can be extended to the analysis of any kind of nuclear fuel.

  17. Performance comparison between high temperature and traditional proton exchange membrane fuel cell stacks using electrochemical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhu, Ying; Zhu, Wenhua H.; Tatarchuk, Bruce J.

    2014-06-01

    A temperature above 100 °C is always desired for proton exchange membrane (PEM) fuel cell operation. It not only improves kinetic and mass transport processes, but also facilitates thermal and water management in fuel cell systems. Increased carbon monoxide (CO) tolerance at higher operating temperature also simplifies the pretreatment of fuel supplement. The novel phosphoric acid (PA) doped polybenzimidazole (PBI) membranes achieve PEM fuel cell operations above 100 °C. The performance of a commercial high temperature (HT) PEM fuel cell stack module is studied by measuring its impedance under various current loads when the operating temperature is set at 160 °C. The contributions of kinetic and mass transport processes to stack impedance are analyzed qualitatively and quantitatively by equivalent circuit (EC) simulation. The performance of a traditional PEM fuel cell stack module operated is also studied by impedance measurement and EC simulation. The operating temperature is self-stabilized between 40 °C and 65 °C. An enhancement of the HT-PEM fuel cell stack in polarization impedance is evaluated by comparing to the traditional PEM fuel cell stack. The impedance study on two commercial fuel cell stacks reveals the real situation of current fuel cell development.

  18. 3D printed sample holder for in-operando EPR spectroscopy on high temperature polymer electrolyte fuel cells

    NASA Astrophysics Data System (ADS)

    Niemöller, Arvid; Jakes, Peter; Kayser, Steffen; Lin, Yu; Lehnert, Werner; Granwehr, Josef

    2016-08-01

    Electrochemical cells contain electrically conductive components, which causes various problems if such a cell is analyzed during operation in an EPR resonator. The optimum cell design strongly depends on the application and it is necessary to make certain compromises that need to be individually arranged. Rapid prototyping presents a straightforward option to implement a variable cell design that can be easily adapted to changing requirements. In this communication, it is demonstrated that sample containers produced by 3D printing are suitable for EPR applications, with a particular emphasis on electrochemical applications. The housing of a high temperature polymer electrolyte fuel cell (HT-PEFC) with a phosphoric acid doped polybenzimidazole membrane was prepared from polycarbonate by 3D printing. Using a custom glass Dewar, this fuel cell could be operated at temperatures up to 140 °C in a standard EPR cavity. The carbon-based gas diffusion layer showed an EPR signal with a characteristic Dysonian line shape, whose evolution could be monitored in-operando in a non-invasive manner.

  19. 3D printed sample holder for in-operando EPR spectroscopy on high temperature polymer electrolyte fuel cells.

    PubMed

    Niemöller, Arvid; Jakes, Peter; Kayser, Steffen; Lin, Yu; Lehnert, Werner; Granwehr, Josef

    2016-08-01

    Electrochemical cells contain electrically conductive components, which causes various problems if such a cell is analyzed during operation in an EPR resonator. The optimum cell design strongly depends on the application and it is necessary to make certain compromises that need to be individually arranged. Rapid prototyping presents a straightforward option to implement a variable cell design that can be easily adapted to changing requirements. In this communication, it is demonstrated that sample containers produced by 3D printing are suitable for EPR applications, with a particular emphasis on electrochemical applications. The housing of a high temperature polymer electrolyte fuel cell (HT-PEFC) with a phosphoric acid doped polybenzimidazole membrane was prepared from polycarbonate by 3D printing. Using a custom glass Dewar, this fuel cell could be operated at temperatures up to 140°C in a standard EPR cavity. The carbon-based gas diffusion layer showed an EPR signal with a characteristic Dysonian line shape, whose evolution could be monitored in-operando in a non-invasive manner.

  20. X-ray photoelectron spectroscopy study of cubic boron nitride single crystals grown under high pressure and high temperature

    NASA Astrophysics Data System (ADS)

    Hou, Lixin; Chen, Zhanguo; Liu, Xiuhuan; Gao, Yanjun; Jia, Gang

    2012-02-01

    The defects, impurities and their bonding states of unintentionally doped cubic boron nitride (cBN) single crystals were investigated by X-ray photoelectron spectroscopy (XPS). The results indicate that nitrogen vacancy (VN) is the main native defect of the cBN crystals since the atomic ratio of B:N is always larger than 1 before Ar ion sputtering. After sputter cleaning, around 6 at% carbon, which probably comes from the growth chamber, remains in the samples as the main impurity. Carbon can substitute nitrogen lattice site and form the bonding states of Csbnd Bsbnd N or Csbnd B, which can be verified by the XPS spectra of C1s, B1s and N1s. The C impurity (acceptor) and N vacancy (donor) can compose the donor-acceptor complex to affect the electrical and optical properties of cBN crystals.

  1. Impedance spectroscopy of the oxide films formed during high temperature oxidation of a cobalt-plated ferritic alloy

    NASA Astrophysics Data System (ADS)

    Velraj, S.; Zhu, J. H.; Painter, A. S.; Du, S. W.; Li, Y. T.

    2014-02-01

    Impedance spectroscopy was used to evaluate the oxide films formed on cobalt-coated Crofer 22 APU ferritic stainless steel after thermal oxidation at 800 °C in air for different times (i.e. 2, 50, 100 and 500 h). Impedance spectra of the oxide films exhibited two or three semicircles depending on the oxidation time, which correspond to the presence of two or three individual oxide layers. Coupled with scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS) and X-ray diffraction (XRD), the individual oxide layer corresponding to each semicircle was determined unambiguously. Impedance spectrum analysis of the oxide films formed on the sample after thermal exposure at 800 °C in air for 2 h led to the identification of the low-frequency and high-frequency semicircles as being from Cr2O3 and Co3O4, respectively. SEM/EDS and XRD analysis of the 500-h sample clearly revealed the presence of three oxide layers, analyzed to be Co3-xCrxO4, CoCr2O4, and Cr2O3. Although the SEM images of the 50-h and 100-h samples did not clearly show the CoCr2O4 layer, impedance plots implied their presence. The oxide scales were assigned to their respective semicircles and the electrical properties of Co3-xCrxO4, CoCr2O4 and Cr2O3 were determined from the impedance data.

  2. Performance and characteristics of a high pressure, high temperature capillary cell with facile construction for operando x-ray absorption spectroscopy.

    PubMed

    Bansode, Atul; Guilera, Gemma; Cuartero, Vera; Simonelli, Laura; Avila, Marta; Urakawa, Atsushi

    2014-08-01

    We demonstrate the use of commercially available fused silica capillary and fittings to construct a cell for operando X-ray absorption spectroscopy (XAS) for the study of heterogeneously catalyzed reactions under high pressure (up to 200 bars) and high temperature (up to 280 °C) conditions. As the first demonstration, the cell was used for CO2 hydrogenation reaction to examine the state of copper in a conventional Cu/ZnO/Al2O3 methanol synthesis catalyst. The active copper component of the catalyst was shown to remain in the metallic state under supercritical reaction conditions, at 200 bars and up to 260 °C. With the coiled heating system around the capillary, one can easily change the length of the capillary and control the amount of catalyst under investigation. With precise control of reactant(s) flow, the cell can mimic and serve as a conventional fixed-bed micro-reactor system to obtain reliable catalytic data. This high comparability of the reaction performance of the cell and laboratory reactors is crucial to gain insights into the nature of actual active sites under technologically relevant reaction conditions. The large length of the capillary can cause its bending upon heating when it is only fixed at both ends because of the thermal expansion. The degree of the bending can vary depending on the heating mode, and solutions to this problem are also presented. Furthermore, the cell is suitable for Raman studies, nowadays available at several beamlines for combined measurements. A concise study of CO2 phase behavior by Raman spectroscopy is presented to demonstrate a potential of the cell for combined XAS-Raman studies.

  3. Performance and characteristics of a high pressure, high temperature capillary cell with facile construction for operando x-ray absorption spectroscopy.

    PubMed

    Bansode, Atul; Guilera, Gemma; Cuartero, Vera; Simonelli, Laura; Avila, Marta; Urakawa, Atsushi

    2014-08-01

    We demonstrate the use of commercially available fused silica capillary and fittings to construct a cell for operando X-ray absorption spectroscopy (XAS) for the study of heterogeneously catalyzed reactions under high pressure (up to 200 bars) and high temperature (up to 280 °C) conditions. As the first demonstration, the cell was used for CO2 hydrogenation reaction to examine the state of copper in a conventional Cu/ZnO/Al2O3 methanol synthesis catalyst. The active copper component of the catalyst was shown to remain in the metallic state under supercritical reaction conditions, at 200 bars and up to 260 °C. With the coiled heating system around the capillary, one can easily change the length of the capillary and control the amount of catalyst under investigation. With precise control of reactant(s) flow, the cell can mimic and serve as a conventional fixed-bed micro-reactor system to obtain reliable catalytic data. This high comparability of the reaction performance of the cell and laboratory reactors is crucial to gain insights into the nature of actual active sites under technologically relevant reaction conditions. The large length of the capillary can cause its bending upon heating when it is only fixed at both ends because of the thermal expansion. The degree of the bending can vary depending on the heating mode, and solutions to this problem are also presented. Furthermore, the cell is suitable for Raman studies, nowadays available at several beamlines for combined measurements. A concise study of CO2 phase behavior by Raman spectroscopy is presented to demonstrate a potential of the cell for combined XAS-Raman studies. PMID:25173285

  4. Performance and characteristics of a high pressure, high temperature capillary cell with facile construction for operando x-ray absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Bansode, Atul; Guilera, Gemma; Cuartero, Vera; Simonelli, Laura; Avila, Marta; Urakawa, Atsushi

    2014-08-01

    We demonstrate the use of commercially available fused silica capillary and fittings to construct a cell for operando X-ray absorption spectroscopy (XAS) for the study of heterogeneously catalyzed reactions under high pressure (up to 200 bars) and high temperature (up to 280 °C) conditions. As the first demonstration, the cell was used for CO2 hydrogenation reaction to examine the state of copper in a conventional Cu/ZnO/Al2O3 methanol synthesis catalyst. The active copper component of the catalyst was shown to remain in the metallic state under supercritical reaction conditions, at 200 bars and up to 260 °C. With the coiled heating system around the capillary, one can easily change the length of the capillary and control the amount of catalyst under investigation. With precise control of reactant(s) flow, the cell can mimic and serve as a conventional fixed-bed micro-reactor system to obtain reliable catalytic data. This high comparability of the reaction performance of the cell and laboratory reactors is crucial to gain insights into the nature of actual active sites under technologically relevant reaction conditions. The large length of the capillary can cause its bending upon heating when it is only fixed at both ends because of the thermal expansion. The degree of the bending can vary depending on the heating mode, and solutions to this problem are also presented. Furthermore, the cell is suitable for Raman studies, nowadays available at several beamlines for combined measurements. A concise study of CO2 phase behavior by Raman spectroscopy is presented to demonstrate a potential of the cell for combined XAS-Raman studies.

  5. The 3R modification of LixTiS2 - insights into local electronic structures from high-temperature in situ NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Wilkening, Martin

    2015-03-01

    Titanium disulphide was one of the very first electrode materials investigated to serve as insertion host in rechargeable, that is secondary lithium-ion batteries. At room temperature the trigonal, layer structured modification exists that can easily accommodate Li ions up to the composition ?. With increasing temperature, however, the present results give evidence that ? (?) transforms into a new crystal structure that is expected to be metastable at room temperature. Here, this high-temperature modification is attributed to the 3R polymorph previously described by Colbow et al. Quite recently, the same phase has been characterized by X-ray diffraction and Rietveld refinement. In the present work, nuclear magnetic resonance (NMR) spectroscopy is used to follow up this transformation in situ; it is able to monitor the associated changes of local electronic structures sensed by the lithium ions. Indeed, via in situ NMR, which has been carried out at temperatures as high as 1023 K, it was possible to directly reveal the evolution of a metastable phase which reversibly forms upon heating the trigonal starting material ?.

  6. Positron Annihilation Lifetime Spectroscopy Study of Neutron Irradiated High Temperature Superconductors YBa2Cu3O7-δ for Application in Fusion Facilities

    NASA Astrophysics Data System (ADS)

    Veterníková, J.; Chudý, M.; Slugeň, V.; Eisterer, M.; Weber, H. W.; Sojak, S.; Petriska, M.; Hinca, R.; Degmová, J.; Sabelová, V.

    2012-02-01

    This study focuses on the crystallographic defects introduced by neutron irradiation and the resulting changes of the superconducting properties in the high temperature superconductor YBa2Cu3O7-δ. This material is considered to be most promising for magnet systems in future fusion reactors. Two different bulk samples, pure non-doped YBa2Cu3O7-δ (YBCO) and multi-seed YBa2Cu3O7-δ doped by platinum (MS2F) were studied prior to and after irradiation in the TRIGA MARK II reactor in Vienna. Neutron irradiation is responsible for a significant enhancement of the critical current densities as well as for a reduction in critical temperature. The accumulation of small open volume defects (<0.5 nm) partially causes those changes. These defects were studied by positron annihilation lifetime spectroscopy at room temperature. A high concentration of Cu-O di-vacancies was found in both samples, which increased with neutron fluence. The defect concentration was significantly reduced after a heat treatment.

  7. High Temperature Protonic Conductors

    NASA Technical Reports Server (NTRS)

    Dynys, Fred; Berger, Marie-Helen; Sayir, Ali

    2007-01-01

    High Temperature Protonic Conductors (HTPC) with the perovskite structure are envisioned for electrochemical membrane applications such as H2 separation, H2 sensors and fuel cells. Successive membrane commercialization is dependent upon addressing issues with H2 permeation rate and environmental stability with CO2 and H2O. HTPC membranes are conventionally fabricated by solid-state sintering. Grain boundaries and the presence of intergranular second phases reduce the proton mobility by orders of magnitude than the bulk crystalline grain. To enhanced protonic mobility, alternative processing routes were evaluated. A laser melt modulation (LMM) process was utilized to fabricate bulk samples, while pulsed laser deposition (PLD) was utilized to fabricate thin film membranes . Sr3Ca(1+x)Nb(2-x)O9 and SrCe(1-x)Y(x)O3 bulk samples were fabricated by LMM. Thin film BaCe(0.85)Y(0.15)O3 membranes were fabricated by PLD on porous substrates. Electron microscopy with chemical mapping was done to characterize the resultant microstructures. High temperature protonic conduction was measured by impedance spectroscopy in wet air or H2 environments. The results demonstrate the advantage of thin film membranes to thick membranes but also reveal the negative impact of defects or nanoscale domains on protonic conductivity.

  8. Investigation on Crude and High-Temperature Heated Coffee Oil by ATR-FTIR Spectroscopy along with Antioxidant and Antimicrobial Properties.

    PubMed

    Raba, Diana Nicoleta; Poiana, Mariana-Atena; Borozan, Aurica Breica; Stef, Marius; Radu, Florina; Popa, Mirela-Viorica

    2015-01-01

    The coffee oil has a promising potential to be used in food industry, but an efficient use, especially in products that required high-temperature heating, depends on its chemical composition and the changes induced by processing. Since there is little information on this topic, the aim of our study was to investigate the crude green and roasted coffee oil (GCO, RCO) and heated (HGCO, HRCO) for 1 h at 200°C, by Fourier Transform Infrared (FTIR) spectroscopy and in terms of antioxidant and antimicrobial properties. The results of FTIR spectroscopy revealed that no statistically significant differences (one-way ANOVA, p>0.05) in the oxidative status of GCO and RCO were found. The coffee oils heating induced significant spectral changes in the regions 3100-3600 cm(-1), 2800-3050 cm(-1) and 1680-1780 cm(-1) proved by the differences in the absorbance ratios A 3009 cm(-1)/A 2922 cm(-1), A 3009 cm(-1)/A 2853 cm(-1), A 3009 cm(-1)/A 1744 cm(-1), A 1744 cm(-1)/A 2922 cm(-1). These alterations were related to the reduction of the unsaturation degree due to primary and secondary oxidation processes of the lipid fraction. The radical scavenging ability of oils investigated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay revealed that the IC50 value of GCO was significantly lower than of RCO (p<0.05). The IC50 values of crude coffee oils were lower than those of heated samples. The antioxidant activity of oils was attributed to both antioxidant compounds with free-radical scavenging capacity and to lipids oxidation products generated by heating. In the first 6 h of incubation, the inhibitory activity of crude oils against E. coli and E. faecalis was not significantly different to the control (p>0.05). Also, HGCO and HRCO showed significantly different inhibitory potential related to the control (p<0.05). The heating induced statistically significant decreases in the effectiveness of coffee oils against the tested bacteria. GCO proved to be the most effective among investigated

  9. Investigation on Crude and High-Temperature Heated Coffee Oil by ATR-FTIR Spectroscopy along with Antioxidant and Antimicrobial Properties

    PubMed Central

    Raba, Diana Nicoleta; Poiana, Mariana-Atena; Borozan, Aurica Breica; Stef, Marius; Radu, Florina; Popa, Mirela-Viorica

    2015-01-01

    The coffee oil has a promising potential to be used in food industry, but an efficient use, especially in products that required high-temperature heating, depends on its chemical composition and the changes induced by processing. Since there is little information on this topic, the aim of our study was to investigate the crude green and roasted coffee oil (GCO, RCO) and heated (HGCO, HRCO) for 1 h at 200°C, by Fourier Transform Infrared (FTIR) spectroscopy and in terms of antioxidant and antimicrobial properties. The results of FTIR spectroscopy revealed that no statistically significant differences (one-way ANOVA, p>0.05) in the oxidative status of GCO and RCO were found. The coffee oils heating induced significant spectral changes in the regions 3100–3600 cm–1, 2800–3050 cm–1 and 1680–1780 cm–1 proved by the differences in the absorbance ratios A 3009 cm−1/A 2922 cm−1, A 3009 cm−1/A 2853 cm−1, A 3009 cm−1/A 1744 cm−1, A 1744 cm−1/A 2922 cm−1. These alterations were related to the reduction of the unsaturation degree due to primary and secondary oxidation processes of the lipid fraction. The radical scavenging ability of oils investigated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay revealed that the IC50 value of GCO was significantly lower than of RCO (p<0.05). The IC50 values of crude coffee oils were lower than those of heated samples. The antioxidant activity of oils was attributed to both antioxidant compounds with free-radical scavenging capacity and to lipids oxidation products generated by heating. In the first 6 h of incubation, the inhibitory activity of crude oils against E. coli and E. faecalis was not significantly different to the control (p>0.05). Also, HGCO and HRCO showed significantly different inhibitory potential related to the control (p<0.05). The heating induced statistically significant decreases in the effectiveness of coffee oils against the tested bacteria. GCO proved to be the most effective among

  10. High temperature reactors

    NASA Astrophysics Data System (ADS)

    Dulera, I. V.; Sinha, R. K.

    2008-12-01

    With the advent of high temperature reactors, nuclear energy, in addition to producing electricity, has shown enormous potential for the production of alternate transport energy carrier such as hydrogen. High efficiency hydrogen production processes need process heat at temperatures around 1173-1223 K. Bhabha Atomic Research Centre (BARC), is currently developing concepts of high temperature reactors capable of supplying process heat around 1273 K. These reactors would provide energy to facilitate combined production of hydrogen, electricity, and drinking water. Compact high temperature reactor is being developed as a technology demonstrator for associated technologies. Design has been also initiated for a 600 MWth innovative high temperature reactor. High temperature reactor development programme has opened new avenues for research in areas like advanced nuclear fuels, high temperature and corrosion resistant materials and protective coatings, heavy liquid metal coolant technologies, etc. The paper highlights design of these reactors and their material related requirements.

  11. High-Temperature Superconductivity

    NASA Astrophysics Data System (ADS)

    Tanaka, Shoji

    2006-12-01

    A general review on high-temperature superconductivity was made. After prehistoric view and the process of discovery were stated, the special features of high-temperature superconductors were explained from the materials side and the physical properties side. The present status on applications of high-temperature superconductors were explained on superconducting tapes, electric power cables, magnets for maglev trains, electric motors, superconducting quantum interference device (SQUID) and single flux quantum (SFQ) devices and circuits.

  12. High temperature sensor

    DOEpatents

    Tokarz, Richard D.

    1982-01-01

    A high temperature sensor includes a pair of electrical conductors separated by a mass of electrical insulating material. The insulating material has a measurable resistivity within the sensor that changes in relation to the temperature of the insulating material within a high temperature range (1,000 to 2,000 K.). When required, the sensor can be encased within a ceramic protective coating.

  13. High-Temperature Superconductivity

    SciTech Connect

    Peter Johnson

    2008-11-05

    Like astronomers tweaking images to gain a more detailed glimpse of distant stars, physicists at Brookhaven National Laboratory have found ways to sharpen images of the energy spectra in high-temperature superconductors — materials that carry electrical c

  14. High temperature pressure gauge

    DOEpatents

    Echtler, J. Paul; Scandrol, Roy O.

    1981-01-01

    A high temperature pressure gauge comprising a pressure gauge positioned in fluid communication with one end of a conduit which has a diaphragm mounted in its other end. The conduit is filled with a low melting metal alloy above the diaphragm for a portion of its length with a high temperature fluid being positioned in the remaining length of the conduit and in the pressure gauge.

  15. High-temperature electronics

    NASA Technical Reports Server (NTRS)

    Matus, Lawrence G.; Seng, Gary T.

    1990-01-01

    To meet the needs of the aerospace propulsion and space power communities, the high temperature electronics program at the Lewis Research Center is developing silicon carbide (SiC) as a high temperature semiconductor material. This program supports a major element of the Center's mission - to perform basic and developmental research aimed at improving aerospace propulsion systems. Research is focused on developing the crystal growth, characterization, and device fabrication technologies necessary to produce a family of SiC devices.

  16. High temperature refrigerator

    DOEpatents

    Steyert, Jr., William A.

    1978-01-01

    A high temperature magnetic refrigerator which uses a Stirling-like cycle in which rotating magnetic working material is heated in zero field and adiabatically magnetized, cooled in high field, then adiabatically demagnetized. During this cycle said working material is in heat exchange with a pumped fluid which absorbs heat from a low temperature heat source and deposits heat in a high temperature reservoir. The magnetic refrigeration cycle operates at an efficiency 70% of Carnot.

  17. High temperature furnace

    DOEpatents

    Borkowski, Casimer J.

    1976-08-03

    A high temperature furnace for use above 2000.degree.C is provided that features fast initial heating and low power consumption at the operating temperature. The cathode is initially heated by joule heating followed by electron emission heating at the operating temperature. The cathode is designed for routine large temperature excursions without being subjected to high thermal stresses. A further characteristic of the device is the elimination of any ceramic components from the high temperature zone of the furnace.

  18. High-temperature sensor

    DOEpatents

    Not Available

    1981-01-29

    A high temperature sensor is described which includes a pair of electrical conductors separated by a mass of electrical insulating material. The insulating material has a measurable resistivity within the sensor that changes in relation to the temperature of the insulating material within a high temperature range (1000 to 2000/sup 0/K). When required, the sensor can be encased within a ceramic protective coating.

  19. Manganese Tetraboride, MnB4: High-Temperature Crystal Structure, p-n Transition, (55)Mn NMR Spectroscopy, Solid Solutions, and Mechanical Properties.

    PubMed

    Knappschneider, Arno; Litterscheid, Christian; Brgoch, Jakoah; George, Nathan C; Henke, Sebastian; Cheetham, Anthony K; Hu, Jerry G; Seshadri, Ram; Albert, Barbara

    2015-05-26

    The structural and electronic properties of MnB4 were studied by high-temperature powder X-ray diffraction and measurements of the conductivity and Seebeck coefficient on spark-plasma-sintered samples. A transition from the room-temperature monoclinic structure (space group P2(1)/c) to a high-temperature orthorhombic structure (space group Pnnm) was observed at about 650 K. The material remained semiconducting after the transition, but its behavior changed from p-type to n-type. (55)Mn NMR measurements revealed an isotropic chemical shift of -1315 ppm, confirming an oxidation state of Mn close to I. Solid solutions of Cr(1-x)Mn(x)B4 (two phases in space groups Pnnm and P2(1)/c) were synthesized for the first time. In addition, nanoindentation studies yielded values of (496±26) and (25.3±1.7) GPa for the Young's modulus and hardness, respectively, compared to values of 530 and 37 GPa obtained by DFT calculations. PMID:25891681

  20. Feasibility of Mossbauer survey meter for hydrocarbon and mineral reserves

    NASA Technical Reports Server (NTRS)

    Singh, J. J.

    1975-01-01

    The feasibility of developing a Mossbauer survey meter for geophysical prospecting was investigated. Various critical requirements that will have to be met by the source and absorber crystals in such an instrument were identified. It was concluded that a survey meter based on (Rh-103 resonance (40 kev) yields Rh-103) isomeric transition is feasible and should be developed.

  1. High-temperature and high-pressure cell for kinetic measurements of supercritical fluids reactions with the use of ultraviolet-visible spectroscopy

    NASA Astrophysics Data System (ADS)

    Gorbaty, Yuri E.; Venardou, Eleni; Garcia-Verdugo, Eduardo; Poliakoff, Martyn

    2003-06-01

    A high-temperature high-pressure ultraviolet-visible (UV-Vis) cell is described. The cell has been designed specifically for use with the UV spectrophotometer Hewlett-Packard 8453 but it could work up to 780 K at 100 MPa with any other UV-Vis spectrophotometer, as well as for near infrared (NIR) experiments. Three features of the cell make it convenient for experiments with supercritical fluids: the possibility to choose an optimal path length, the presence of three interchangeable ports into the cell, and a movable thermocouple in the working zone of the cell. The cell has been used to study a range of chemical reactions in water under near-critical and supercritical conditions, as well as for measuring the kinetics of such reactions. Some examples illustrating the performance of the cell are given.

  2. Mossbauer research of Fe/Co nanotubes based on track membranes

    NASA Astrophysics Data System (ADS)

    Kozlovskiy, A.; Zhanbotin, A.; Zdorovets, M.; Manakova, I.; Ozernoy, A.; Kiseleva, T.; Kadyrzhanov, K.; Rusakov, V.; Kanyukov, E.

    2016-08-01

    Fe/Co nanostructures obtained by template synthesis have been researched in this study. It was shown that the obtained nanostructures are single-phase Fe/Co nanotubes with a high degree of polycrystallinity and body-centered cubic structure with a length of 12 μm, possessing diameter of 110 ± 5 nm, and wall thickness of 18-20 nm. The direction of easy magnetization axis lies along the nanotubes axis due to the anisotropy shape of the nanotubes. Mossbauer spectroscopy showed that the hyperfine magnetic field (Hn) values on 57Fe nuclei increase with increasing number of Co atoms near Fe atoms. Substitution of one Fe atom on Co atom leads to an increase of (Hn) to approximately 9.0 ± 0.4 KOe, herewith shift of the Mossbauer line decreasing to about 0.004 ± 0.002 mm/s. The local magnetic texture along the nanotubes axis was found with the average angle between magnetic moment and the nanotubes axis ϑ bar = 25 - 29 ° .

  3. High-Temperature Superconductivity

    ScienceCinema

    Peter Johnson

    2016-07-12

    Like astronomers tweaking images to gain a more detailed glimpse of distant stars, physicists at Brookhaven National Laboratory have found ways to sharpen images of the energy spectra in high-temperature superconductors — materials that carry electrical c

  4. High temperature storage loop :

    SciTech Connect

    Gill, David Dennis; Kolb, William J.

    2013-07-01

    A three year plan for thermal energy storage (TES) research was created at Sandia National Laboratories in the spring of 2012. This plan included a strategic goal of providing test capability for Sandia and for the nation in which to evaluate high temperature storage (>650ÀC) technology. The plan was to scope, design, and build a flow loop that would be compatible with a multitude of high temperature heat transfer/storage fluids. The High Temperature Storage Loop (HTSL) would be reconfigurable so that it was useful for not only storage testing, but also for high temperature receiver testing and high efficiency power cycle testing as well. In that way, HTSL was part of a much larger strategy for Sandia to provide a research and testing platform that would be integral for the evaluation of individual technologies funded under the SunShot program. DOEs SunShot program seeks to reduce the price of solar technologies to 6/kWhr to be cost competitive with carbon-based fuels. The HTSL project sought to provide evaluation capability for these SunShot supported technologies. This report includes the scoping, design, and budgetary costing aspects of this effort

  5. Alpha particle spectroscopy — A useful tool for the investigation of spent nuclear fuel from high temperature gas-cooled reactors

    NASA Astrophysics Data System (ADS)

    Helmbold, M.

    1984-06-01

    For more than a decade, alpha particle spectrometry of spent nuclear fuel has been used at the Kernforschungsanlage Jülich (KFA) in the field of research for the German high temperature reactor (HTR). Techniques used for the preparation of samples for alpha spectrometry have included deposition from aqueous solutions of spent fuel, annealing of fuel particles in an oven and the evaporation of fuel material by a laser beam. The resulting sources are very thin but of low activity and the alpha spectrometry data obtained from them must be evaluated with sophisticated computer codes to achieve the required accuracy. Measurements have been made on high and low enriched uranium fuel and on a variety of parameters relevant to the fuel cycle. In this paper the source preparation and data evaluation techniques will be discussed together with the results obtained to data, i.e. production of alpha active actinide isotopes, correlations between actinide isotopes and fission products, build up and transmutation of actinides during burn-up of HTR fuel, diffusion coefficients of actinides for fuel particle kernels and coating materials. All these KFA results have helped to establish the basis for the design, licensing and operation of HTR power plants, including reprocessing and waste management.

  6. High Temperature ESP Monitoring

    SciTech Connect

    Jack Booker; Brindesh Dhruva

    2011-06-20

    The objective of the High Temperature ESP Monitoring project was to develop a downhole monitoring system to be used in wells with bottom hole well temperatures up to 300°C for measuring motor temperature, formation pressure, and formation temperature. These measurements are used to monitor the health of the ESP motor, to track the downhole operating conditions, and to optimize the pump operation. A 220 ºC based High Temperature ESP Monitoring system was commercially released for sale with Schlumberger ESP motors April of 2011 and a 250 ºC system with will be commercially released at the end of Q2 2011. The measurement system is now fully qualified, except for the sensor, at 300 °C.

  7. High Temperature Thermosets

    NASA Technical Reports Server (NTRS)

    Hergenrother, Paul M.

    1999-01-01

    A thermoset or network polymer is an organic material where the molecules are tied together through chemical bonds (crosslinks) and therefore they cannot move past one another. As a result, these materials exhibit a certain degree of dimensional stability. The chemical composition and the degree of crosslink density of the thermoset have a pronounced effect upon the properties. High temperature thermosets offer a favorable combination of properties that makes them attractive for many applications. Their most important features are the excellent processability particularly of the low molecular weight precusor forms, the chemical and solvent resistance and the dimensional stability. The market for high temperature thermosets will increase as new uses for them are uncovered and new thermosets with better combinations of properties are developed.

  8. High temperature future

    SciTech Connect

    Sheinkopf, K.

    1994-09-01

    During the past few years, there have been dramatic accomplishments and success of high temperature solar thermal systems and significant development of these systems. High temperature technologies, about 500 F and higher, such as dish engines, troughs, central receiver power towers and solar process heat systems, have been tested, demonstrated and used in an array of applications, including many cost-effective utility bulk power production and demand side supply projects in the United States. Large systems provide power and hot water to prisons, schools, nursing homes and other institutions. Joint ventures with industry, utility projects, laboratory design assistance and other activities are building a solid industry of US solar thermal systems ready for use today.

  9. High temperature probe

    DOEpatents

    Swan, Raymond A.

    1994-01-01

    A high temperature probe for sampling, for example, smokestack fumes, and is able to withstand temperatures of 3000.degree. F. The probe is constructed so as to prevent leakage via the seal by placing the seal inside the water jacket whereby the seal is not exposed to high temperature, which destroys the seal. The sample inlet of the probe is also provided with cooling fins about the area of the seal to provide additional cooling to prevent the seal from being destroyed. Also, a heated jacket is provided for maintaining the temperature of the gas being tested as it passes through the probe. The probe includes pressure sensing means for determining the flow velocity of an efficient being sampled. In addition, thermocouples are located in various places on the probe to monitor the temperature of the gas passing there through.

  10. a Mossbauer Effect Study of Iron(iii) Dithiocarbamates.

    NASA Astrophysics Data System (ADS)

    Fiddy, Judith Mary

    Available from UMI in association with The British Library. Ever since the pioneering work of Cambi iron(III) trisdithiocarbamates, which have the formula Fe(R _2NCS_2]_3 where R is an alkyl or an aryl group, have formed the basis for understanding spin-state equilibria in iron(III) complexes. Magnetic and infrared studies clearly indicate equilibrium between the high-spin and low-spin states. The Mossbauer spectra, however, show only a single component, indicating rapid relaxation between the two spin states on the Mossbauer timescale. It has been assumed that the spectral parameters are therefore a function of the relative spin-state populations. In this thesis, the results of Mossbauer experiments carried out on a series of iron(III) trisdithiocarbamates with various organic substituents, known to give a range of high-spin and low-spin state populations at room temperature, are presented. An iron(III) bisdithiocarbamate complex, Fe^{57} ((C_5 H_{10})_2NCS _2]_2NCS, was also investigated. The samples were studied at temperatures from 1.3K to 295K, and at pressures between atmospheric pressure and 80kbar at room temperature only. It was found that, in fact, the spin-equilibrium plays only a minor role in determining the Mossbauer spectra of the trisdithiocarbamate compounds. The effects of spin -state relaxation on the temperature dependence of the spectra are, in general, masked by those of slow paramagnetic relaxation which, in contrast to the effects of the spin-equilibrium, are marked and different for each compound. By fitting the spectra to models of paramagnetic relaxation the temperature dependence of the relaxation rates and possible directions of the magnetic hyperfine field relative to the major axis of the electric field gradient were found. The pressure dependence of the spectra was found to be rather similar for all the compounds, the main differences being in the widths and in the asymmetry of the areas of the spectral lines. Both these effects can

  11. HIGH TEMPERATURE THERMOCOUPLE

    DOEpatents

    Eshayu, A.M.

    1963-02-12

    This invention contemplates a high temperature thermocouple for use in an inert or a reducing atmosphere. The thermocouple limbs are made of rhenium and graphite and these limbs are connected at their hot ends in compressed removable contact. The rhenium and graphite are of high purity and are substantially stable and free from diffusion into each other even without shielding. Also, the graphite may be thick enough to support the thermocouple in a gas stream. (AEC)

  12. High Temperature Capacitor Development

    SciTech Connect

    John Kosek

    2009-06-30

    The absence of high-temperature electronics is an obstacle to the development of untapped energy resources (deep oil, gas and geothermal). US natural gas consumption is projected to grow from 22 trillion cubic feet per year (tcf) in 1999 to 34 tcf in 2020. Cumulatively this is 607 tcf of consumption by 2020, while recoverable reserves using current technology are 177 tcf. A significant portion of this shortfall may be met by tapping deep gas reservoirs. Tapping these reservoirs represents a significant technical challenge. At these depths, temperatures and pressures are very high and may require penetrating very hard rock. Logistics of supporting 6.1 km (20,000 ft) drill strings and the drilling processes are complex and expensive. At these depths up to 50% of the total drilling cost may be in the last 10% of the well depth. Thus, as wells go deeper it is increasingly important that drillers are able to monitor conditions down-hole such as temperature, pressure, heading, etc. Commercial off-the-shelf electronics are not specified to meet these operating conditions. This is due to problems associated with all aspects of the electronics including the resistors and capacitors. With respect to capacitors, increasing temperature often significantly changes capacitance because of the strong temperature dependence of the dielectric constant. Higher temperatures also affect the equivalent series resistance (ESR). High-temperature capacitors usually have low capacitance values because of these dielectric effects and because packages are kept small to prevent mechanical breakage caused by thermal stresses. Electrolytic capacitors do not operate at temperatures above 150oC due to dielectric breakdown. The development of high-temperature capacitors to be used in a high-pressure high-temperature (HPHT) drilling environment was investigated. These capacitors were based on a previously developed high-voltage hybridized capacitor developed at Giner, Inc. in conjunction with a

  13. High Temperature Elastic Properties of Single Crystal Mullite (Approximately 2.5Al2O3.SiO2) by Brillouin Spectroscopy

    NASA Technical Reports Server (NTRS)

    Palko, James W.; Sayir, Ali; Sinogeikin, Stanislav V.; Kriven, Waltraud M.; Bass, Jay D.; Farmer, Serene C. (Technical Monitor)

    2001-01-01

    The complete elastic tensor of mullite has been determined by brillouin spectroscopy at room temperature and elevated temperatures up to 1200C. Equivalent, isotropic moduli (bulk, shear, and Young's) have been calculated. The room temperature values obtained using Voigt-Reuss-Hill averaging are: K(sub VRH) = 173.5 + 6.9 GPa, G(sub VRH) = 88.0 + 3.5 GPa, E(sub VRH) = 225.9 + 9.0 GPa. All moduli show relatively gradual decreases with temperature. The temperature derivatives obtained for the equivalent, isotropic moduli are: dK(sub VRH)/dT = - 17.5 + 2.5 MPa/deg. C, dG(sub VRH)/dT = -8.8 + 1.4 MPa/deg. C, dE(sub VRH)/dT = -22.6 + 2.8 MPa/deg C. Substantial differences between bulk properties calculated from the single crystal measurements in this study and the properties reported in the literature for polycrystalline sintered mullite are identified, indicating the importance of factors such as microstructure, intergranular phases, and composition to the elasticity of mullite ceramics.

  14. Theoretical investigation of hyperfine field parameters through mossbauer gamma ray

    SciTech Connect

    Ali, Sikander; Hashim, Mohd

    2012-06-05

    When a Mossbauer gamma-ray emitting or absorbing nucleus is placed in a crystalline environment, the quadrupole moment of the nucleus interacts with the electric field gradient set up by the ligands around it. In the transition |7/2>{yields}|5/2> twelve lines are obtained. Applying the multipole radiation field theory and density matrix formalism, the determinant of coherency matrix, intensity and degree of polarization have been calculated for each line.

  15. X-ray spectral and Mossbauer investigations of structure defects and the degree of inversion of manganese-zinc ferrites

    NASA Astrophysics Data System (ADS)

    Kirichok, P. P.; Pashchenko, V. P.; Kompaniets, V. I.; Brovkina, G. T.

    1982-03-01

    X-ray and Mossbauer spectroscopy is used to investigate the effect of vacuum cooling on the valence of cations of manganese and iron, nonstoichiometry and the degree of inversion of manganese-zinc ferrites. The dependence of the valency of the cations of manganese and iron, the degree of inversion, and the degree of nonstoichiometry on the partial pressure of oxygen produced in the cooling stage is established. An interrelationship is found between the defects and the degree of inversion of manganese-zinc ferrites.

  16. High temperature detonator

    DOEpatents

    Johnson, James O.; Dinegar, Robert H.

    1988-01-01

    A detonator assembly is provided which is usable at high temperatures about 300.degree. C. A detonator body is provided with an internal volume defining an anvil surface. A first acceptor explosive is disposed on the anvil surface. A donor assembly having an ignition element, an explosive material, and a flying plate, are placed in the body effective to accelerate the flying plate to impact the first acceptor explosive on the anvil for detonating the first acceptor explosive. A second acceptor explosive is eccentrically located in detonation relationship with the first acceptor explosive to thereafter effect detonation of a main charge.

  17. High temperature geophysical instrumentation

    SciTech Connect

    Hardee, H.C.

    1988-06-01

    The instrumentation development program was to proceed in parallel with scientific research and was driven by the needs of researchers. The development of these instruments has therefore included numerous geophysical field tests, many of which have resulted in the publication of scientific articles. This paper is a brief summary of some of the major geophysical instruments that have been developed and tested under the High Temperature Geophysics Program. These instruments are briefly described and references are given for further detailed information and for scientific papers that have resulted from the use of these instruments. 9 refs., 14 figs.

  18. High temperature drilling fluids

    SciTech Connect

    Stong, R.E.; Walinsky, S.W.

    1986-01-28

    This patent describes an aqueous drilling fluid suitable for high-temperature use. This fluid is composed of a water base. Clay is suspended in the base and from about 0.01-25 pounds per barrel total composition of a hydrolyzed terpolymer of maleic anhydride, styrene and a third monomer selected from acrylamide, methacrylamide, acrylic acid and metacrylic acid. The molar ratio of maleic anhydride to styrene to the third monomer is from about 30:10:60 to 50:40:10, and the alkali metal, ammonium and lower aliphatic amine salts thereof, the weight-average molecular weight of the hydrolyzed terpolymer is from about 500-10,000.

  19. Internally consistent elasticity measurements of mantle minerals at high-pressure and high-temperature by Brillouin spectroscopy and X-ray diffraction

    NASA Astrophysics Data System (ADS)

    Marquardt, H.; Kurnosov, A.; Boffa Ballaran, T.; Marquardt, K.; Frost, D. J.; Buchen, J.; Schulze, K.

    2015-12-01

    Elasticity is a material property that reflects the atomic structure and interatomic forces in crystalline materials. As a result, elastic properties are strongly affected by changes in pressure and temperature. In Earth Sciences, knowledge of the elastic behavior of geomaterials at pressure and temperature conditions of the Earth's interior is key to constrain our planet's inner structure and dynamics through forward modelling of seismic observables. Here, we will discuss internally consistent single-crystal elasticity measurements that combine the opportunities emerging from the recent development of combined Brillouin scattering (to derive acoustic wave velocities) and x-ray diffraction (XRD) systems (for structure and unit-cell parameter determination) with the advantages of sophisticated sample preparation using the focused ion beam (FIB) technique [1]. We will show results of experiments on mantle minerals that were performed using the combined Brillouin scattering and rotating anode XRD system at the Bayerisches Geoinstitut BGI. Multiple single-crystals, FIB-tailored in size and shape, were loaded in the single sample chambers of resistively-heated diamond-anvil cells (DAC). Such a multi-sample approach allows for internally consistent determinations of all independent elastic constants from low-symmetry crystals by Brillouin spectroscopy and x-ray diffraction measurements. Furthermore, the multi-sample approach facilitates direct quantification of the effects of chemical substitution on the structure and elasticity of high-symmetry crystals at non-ambient conditions. Our experimental approach eliminates uncertainties arising from the combination of data collected under (potentially) different conditions in several DAC runs, in different laboratories and/or from using different pressure-temperature sensors. We will also discuss the possibility to derive pressure independent from a secondary pressure scale. [1] H. Marquardt, K. Marquardt, Am. Mineral. 97, 299

  20. High temperature thermometric phosphors

    DOEpatents

    Allison, Stephen W.; Cates, Michael R.; Boatner, Lynn A.; Gillies, George T.

    1999-03-23

    A high temperature phosphor consists essentially of a material having the general formula LuPO.sub.4 :Dy.sub.(x),Eu.sub.y) wherein: 0.1 wt %.ltoreq.x.ltoreq.20 wt % and 0.1 wt %.ltoreq.y.ltoreq.20 wt %. The high temperature phosphor is in contact with an article whose temperature is to be determined. The article having the phosphor in contact with it is placed in the environment for which the temperature of the article is to be determined. The phosphor is excited by a laser causing the phosphor to fluoresce. The emission from the phosphor is optically focused into a beam-splitting mirror which separates the emission into two separate emissions, the emission caused by the dysprosium dopant and the emission caused by the europium dopent. The separated emissions are optically filtered and the intensities of the emission are detected and measured. The ratio of the intensity of each emission is determined and the temperature of the article is calculated from the ratio of the intensities of the separate emissions.

  1. High temperature thermometric phosphors

    DOEpatents

    Allison, S.W.; Cates, M.R.; Boatner, L.A.; Gillies, G.T.

    1999-03-23

    A high temperature phosphor consists essentially of a material having the general formula LuPO{sub 4}:Dy{sub x},Eu{sub y} wherein: 0.1 wt % {<=} x {<=} 20 wt % and 0.1 wt % {<=} y {<=} 20 wt %. The high temperature phosphor is in contact with an article whose temperature is to be determined. The article having the phosphor in contact with it is placed in the environment for which the temperature of the article is to be determined. The phosphor is excited by a laser causing the phosphor to fluoresce. The emission from the phosphor is optically focused into a beam-splitting mirror which separates the emission into two separate emissions, the emission caused by the dysprosium dopant and the emission caused by the europium dopant. The separated emissions are optically filtered and the intensities of the emission are detected and measured. The ratio of the intensity of each emission is determined and the temperature of the article is calculated from the ratio of the intensities of the separate emissions. 2 figs.

  2. High temperature filter materials

    SciTech Connect

    Alvin, M.A.; Lippert, T.E.; Bachovchin, D.M.; Tressler, R.E.

    1992-12-01

    Objectives of this program are to identify the potential long-term thermal/chemical effects that advanced coal-based power generating system environments 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. We have principally focused our efforts on developing an understanding of the stability of the alumina/mullite filter material at high temperature (i.e., 870, 980, and 1100{degrees}C) under oxidizing conditions which contain gas phase alkali species. Testing has typically been performed in two continuous flow-through, high temperature test facilities at the Westinghouse Science and Technology Center, using 7 cm diameter {times} 6.4 mm thick discs. (Alvin, 1992) Each disc of ceramic filter material is exposed for periods of 100 to 3,000 hours in duration. Additional efforts have been performed at Westinghouse to broaden our understanding of the stability of cordierite, cordierite-silicon nitride, reaction and sintered silicon nitride, and clay bonded silicon carbide under similar simulated advanced coal fired process conditions. The results of these efforts are presented in this paper.

  3. High temperature filter materials

    SciTech Connect

    Alvin, M.A.; Lippert, T.E.; Bachovchin, D.M. . Science and Technology Center); Tressler, R.E. )

    1992-01-01

    Objectives of this program are to identify the potential long-term thermal/chemical effects that advanced coal-based power generating system environments 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. We have principally focused our efforts on developing an understanding of the stability of the alumina/mullite filter material at high temperature (i.e., 870, 980, and 1100[degrees]C) under oxidizing conditions which contain gas phase alkali species. Testing has typically been performed in two continuous flow-through, high temperature test facilities at the Westinghouse Science and Technology Center, using 7 cm diameter [times] 6.4 mm thick discs. (Alvin, 1992) Each disc of ceramic filter material is exposed for periods of 100 to 3,000 hours in duration. Additional efforts have been performed at Westinghouse to broaden our understanding of the stability of cordierite, cordierite-silicon nitride, reaction and sintered silicon nitride, and clay bonded silicon carbide under similar simulated advanced coal fired process conditions. The results of these efforts are presented in this paper.

  4. High Temperature Piezoelectric Drill

    NASA Technical Reports Server (NTRS)

    Bao, Xiaoqi; Scott, James; Boudreau, Kate; Bar-Cohen, Yoseph; Sherrit, Stewart; Badescu, Mircea; Shrout, Tom; Zhang, Shujun

    2009-01-01

    The current NASA Decadal mission planning effort has identified Venus as a significant scientific target for a surface in-situ sampling/analyzing mission. The Venus environment represents several extremes including high temperature (460 deg C), high pressure (9 MPa), and potentially corrosive (condensed sulfuric acid droplets that adhere to surfaces during entry) environments. This technology challenge requires new rock sampling tools for these extreme conditions. Piezoelectric materials can potentially operate over a wide temperature range. Single crystals, like LiNbO3, have a Curie temperature that is higher than 1000 deg C and the piezoelectric ceramics Bismuth Titanate higher than 600 deg C. A study of the feasibility of producing piezoelectric drills that can operate in the temperature range up to 500 deg C was conducted. The study includes the high temperature properties investigations of engineering materials and piezoelectric ceramics with different formulas and doping. The drilling performances of a prototype Ultrasonic/Sonic Drill/Corer (USDC) using high temperate piezoelectric ceramics and single crystal were tested at temperature up to 500 deg C. The detailed results of our study and a discussion of the future work on performance improvements are presented in this paper.

  5. High-Temperature Optical Window Design

    NASA Technical Reports Server (NTRS)

    Roeloffs, Norman; Taranto, Nick

    1995-01-01

    A high-temperature optical window is essential to the optical diagnostics of high-temperature combustion rigs. Laser Doppler velocimetry, schlieren photography, light sheet visualization, and laser-induced fluorescence spectroscopy are a few of the tests that require optically clear access to the combustor flow stream. A design was developed for a high-temperature window that could withstand the severe environment of the NASA Lewis 3200 F Lean Premixed Prevaporized (LPP) Flame Tube Test Rig. The development of this design was both time consuming and costly. This report documents the design process and the lessons learned, in an effort to reduce the cost of developing future designs for high-temperature optical windows.

  6. High temperature adsorption measurements

    SciTech Connect

    Bertani, R.; Parisi, L.; Perini, R.; Tarquini, B.

    1996-12-31

    Adsorption phenomena are a rich and rather new field of study in geothermal research, in particular at very high temperature. ENEL is interested in the exploitation of geothermal regions with super-heated steam, and it is important to understand the behavior of water-rock interaction. We have analyzed in the 170-200{degrees}C temperature range four samples of Monteverdi cuttings; the next experimental effort will be at 220{degrees}C and over in 1996. The first results of the 1995 runs are collected in this paper. We can highlight four main items: (1) At relative pressures over 0.6 the capillarity forces are very important. (2) There is no significant temperature effect. (3) Adsorbed water can be present, and it is able to multiply by a factor of 15 the estimated reserve of super-heated steam only. (4) Pores smaller than 15 {Angstrom} do not contribute to the adsorbed mass.

  7. High temperature strain gages

    NASA Technical Reports Server (NTRS)

    Gregory, Otto J. (Inventor); You, Tao (Inventor)

    2011-01-01

    A ceramic strain gage based on reactively sputtered indium-tin-oxide (ITO) thin films is used to monitor the structural integrity of components employed in aerospace propulsion systems operating at temperatures in excess of 1500.degree. C. A scanning electron microscopy (SEM) of the thick ITO sensors reveals a partially sintered microstructure comprising a contiguous network of submicron ITO particles with well defined necks and isolated nanoporosity. Densification of the ITO particles was retarded during high temperature exposure with nitrogen thus stabilizing the nanoporosity. ITO strain sensors were prepared by reactive sputtering in various nitrogen/oxygen/argon partial pressures to incorporate more nitrogen into the films. Under these conditions, sintering and densification of the ITO particles containing these nitrogen rich grain boundaries was retarded and a contiguous network of nano-sized ITO particles was established.

  8. High temperature materials characterization

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.

    1990-01-01

    A lab facility for measuring elastic moduli up to 1700 C was constructed and delivered. It was shown that the ultrasonic method can be used to determine elastic constants of materials from room temperature to their melting points. The ease in coupling high frequency acoustic energy is still a difficult task. Even now, new coupling materials and higher power ultrasonic pulsers are being suggested. The surface was only scratched in terms of showing the full capabilities of either technique used, especially since there is such a large learning curve in developing proper methodologies to take measurements into the high temperature region. The laser acoustic system does not seem to have sufficient precision at this time to replace the normal buffer rod methodology.

  9. High temperature adsorption measurements

    SciTech Connect

    Bertani, R.; Parisi, L.; Perini, R.; Tarquini, B.

    1996-01-24

    Adsorption phenomena are a rich and rather new field of study in geothermal research, in particular at very high temperature. ENEL is interested in the exploitation of geothermal regions with superheated steam, and it is important to understand the behavior of water-rock interaction. We have analyzed in the 170-200 °C temperature range four samples of Monteverdi cuttings; the next experimental effort will be at 220 °C and over in 1996. The first results of the 1995 runs are collected in this paper. We can highlight four main items: 1. At relative pressures over 0.6 the capillarity forces are very important. 2. There is no significant temperature effect. 3. Adsorbed water can be present, and it is able to multiply by a factor of 15 the estimated reserve of super-heated steam only. 4. Pores smaller than 15 Å do not contribute to the adsorbed mass.

  10. High temperature measuring device

    DOEpatents

    Tokarz, Richard D.

    1983-01-01

    A temperature measuring device for very high design temperatures (to 2,000.degree. C.). The device comprises a homogenous base structure preferably in the form of a sphere or cylinder. The base structure contains a large number of individual walled cells. The base structure has a decreasing coefficient of elasticity within the temperature range being monitored. A predetermined quantity of inert gas is confined within each cell. The cells are dimensionally stable at the normal working temperature of the device. Increases in gaseous pressure within the cells will permanently deform the cell walls at temperatures within the high temperature range to be measured. Such deformation can be correlated to temperature by calibrating similarly constructed devices under known time and temperature conditions.

  11. High temperature structural silicides

    SciTech Connect

    Petrovic, J.J.

    1997-03-01

    Structural silicides have important high temperature applications in oxidizing and aggressive environments. Most prominent are MoSi{sub 2}-based materials, which are borderline ceramic-intermetallic compounds. MoSi{sub 2} single crystals exhibit macroscopic compressive ductility at temperatures below room temperature in some orientations. Polycrystalline MoSi{sub 2} possesses elevated temperature creep behavior which is highly sensitive to grain size. MoSi{sub 2}-Si{sub 3}N{sub 4} composites show an important combination of oxidation resistance, creep resistance, and low temperature fracture toughness. Current potential applications of MoSi{sub 2}-based materials include furnace heating elements, molten metal lances, industrial gas burners, aerospace turbine engine components, diesel engine glow plugs, and materials for glass processing.

  12. Better high temperature sealing

    SciTech Connect

    Adams, W.V.

    1987-01-01

    Acceptance of welded metal bellows designs, superior seal face materials and advancement of environmental control systems has extended the limits of mechanical seals to the operating limits of the process systems themselves. The nonpusher type welded metal bellows designs have overcome past seal hang-up problems. Material combinations such as silicon carbide versus silicon carbide and silicon carbide versus tungsten carbide have proven to be capable of handling the harsh abrasives encountered on high temperature sealing applications. Steam purges have done a good job of flushing away the deposits and sludges that form on the atmospheric side of the seal and cause seal hang-up. Today's field experience shows that hot water at temperatures up to 350/sup 0/F in the seal cavity can be handled with nothing more than a bypass flush per API piping plan 11 as long as adequate vapor pressure of the fluid is available. For temperatures above 350/sup 0/F, only moderate cooling is now required on hot water applications, where full cooling and a reduction of the seal cavity temperature to something below 180/sup 0/F were once necessary. Initially, the move towards high temperature seals was made for safety, long seal life and reliability reasons. Users wanted seals on their equipment that would avoid the danger of catastrophic seal failures in the event the environmental control systems failed. More recently, the economic advantages of running seals hot have been recognized. It is estimated that an annual savings of $1,000 per inch of shaft size can be realized for every 100/sup 0/F of cooling requirements that can be removed from the seal cavity. This cost savings is due to the elimination or reduction of energy sources used to cool the mechanical seal.

  13. Micro Raman, Mossbauer and magnetic studies of manganese substituted zinc ferrite nanoparticles: Role of Mn

    NASA Astrophysics Data System (ADS)

    Thota, Suneetha; Kashyap, Subhash C.; Sharma, Shiv K.; Reddy, V. R.

    2016-04-01

    A series of Mn-Zn Ferrite nanoparticles (<15 nm) with formula MnxZn1-xFe2O4 (where x=0.00, 0.35, 0.50, 0.65) were successfully prepared by citrate-gel method at low temperature (400 °C). X-ray diffraction analysis confirmed the formation of single cubic spinel phase in these nanoparticles. The FESEM and TEM micrographs revealed the nanoparticles to be nearly spherical in shape and of fairly uniform size. The fractions of Mn2+, Zn2+ and Fe3+ cations occupying tetrahedral sites along with Fe occupying octahedral sites within the unit cell of different ferrite samples are estimated by room temperature micro-Raman spectroscopy. Low temperature Mossbauer measurement on Mn0.5Zn0.5Fe2O4 has reconfirmed the mixed spinel phase of these nanoparticles. Room temperature magnetization studies (PPMS) of Mn substituted samples showed superparamagnetic behavior. Manganese substitution for Zn in the ferrite caused the magnetization to increase from 04 to18 emu/g and Lande's g factor (estimated from ferromagnetic resonance measurement) from 2.02 to 2.12 when x was increased up to 0.50. The FMR has shown that higher Mn cationic substitution leads to increase in dipolar interaction and decrease in super exchange interaction. Thermomagnetic (M-T) and magnetization (M-H) measurements have shown that the increase in Mn concentration (up to x=0.50) enhances the spin ordering temperature up to 150 K (blocking temperature). Magnetocrystalline anisotropy in the nanoparticles was established by Mossbauer, ferromagnetic resonance and thermomagnetic measurements. The optimized substitution of manganese for zinc improves the magnetic properties and makes these nanoparticles a potential candidate for their applications in microwave region and biomedical field.

  14. High temperature interfacial superconductivity

    SciTech Connect

    Bozovic, Ivan; Logvenov, Gennady; Gozar, Adrian Mihai

    2012-06-19

    High-temperature superconductivity confined to nanometer-scale interfaces has been a long standing goal because of potential applications in electronic devices. The spontaneous formation of a superconducting interface in bilayers consisting of an insulator (La.sub.2CuO.sub.4) and a metal (La.sub.1-xSr.sub.xCuO.sub.4), neither of which is superconducting per se, is described. Depending upon the layering sequence of the bilayers, T.sub.c may be either .about.15 K or .about.30 K. This highly robust phenomenon is confined to within 2-3 nm around the interface. After exposing the bilayer to ozone, T.sub.c exceeds 50 K and this enhanced superconductivity is also shown to originate from a 1 to 2 unit cell thick interfacial layer. The results demonstrate that engineering artificial heterostructures provides a novel, unconventional way to fabricate stable, quasi two-dimensional high T.sub.c phases and to significantly enhance superconducting properties in other superconductors. The superconducting interface may be implemented, for example, in SIS tunnel junctions or a SuFET.

  15. Instabilities of High Temperature Superconductors

    PubMed Central

    Matthias, B. T.; Corenzwit, E.; Cooper, A. S.; Longinotti, L. D.

    1971-01-01

    We have observed the transition temperature of both the cubic and tetragonal phases of several high-temperature β-W superconductors. The instability of the cubic lattice appears to be characteristic of high-temperature superconductors. PMID:16591897

  16. High Temperature Superconducting Materials Database

    National Institute of Standards and Technology Data Gateway

    SRD 149 NIST High Temperature Superconducting Materials Database (Web, free access)   The NIST High Temperature Superconducting Materials Database (WebHTS) provides evaluated thermal, mechanical, and superconducting property data for oxides and other nonconventional superconductors.

  17. A computer program for analyzing unresolved Mossbauer hyperfine spectra

    NASA Technical Reports Server (NTRS)

    Schiess, J. R.; Singh, J. J.

    1978-01-01

    The program for analyzing unresolved Mossbauer hyperfine spectra was written in FORTRAN 4 language for the Control Data CYBER 170 series digital computer system with network operating system 1.1. With the present dimensions, the program requires approximately 36,000 octal locations of core storage. A typical case involving two innermost coordination shells in which the amplitudes and the peak positions of all three components were estimated in 25 iterations requires 30 seconds on CYBER 173. The program was applied to determine the effects of various near neighbor impurity shells on hyperfine fields in dilute FeAl alloys.

  18. High Temperature Aquifer Storage

    NASA Astrophysics Data System (ADS)

    Ueckert, Martina; Niessner, Reinhard; Baumann, Thomas

    2015-04-01

    Combined heat and power generation (CHP) is highly efficient because excess heat is used for heating and/or process energy. However, the demand of heat energy varies considerably throughout the year while the demand for electrical energy is rather constant. It seems economically and ecologically highly beneficial for municipalities and large power consumers such as manufacturing plants to store excess heat in groundwater aquifers and to recuperate this energy at times of higher demand. Apart from the hydrogeological conditions, high transmissivity and favorable pressure gradients, the hydrochemical conditions are crucial for long-term operation. Within the project High Temperature Aquifer Storage, scientists investigate storage and recuperation of excess heat energy into the bavarian Malm aquifer. After one year of planning, construction, and the successful drilling of a research well to 495 m b.s.l. the first large scale heat storage test in the Malm aquifer was finished just before Christmas 2014. An enormous technical challenge was the disruption of the carbonate equilibrium - modeling results indicated a carbonate precipitation of 10-50 kg/d in the heat exchangers. The test included five injection pulses of hot water (60 °C up to 110 °C) and four tracer pulses, each consisting of a reactive and a conservative fluorescent dye. Injection and production rates were 15 L/s. About 4 TJ of heat energy were necessary to achieve the desired water temperatures. Electrical conductivity, pH and temperature were recorded at a bypass where also samples were taken. A laboratory container at the drilling site was equipped for the analysis of the concentration of the tracers and the cation concentrations at sampling intervals of down to 15 minutes. Additional water samples were taken and analyzed for major ions and trace elements in the laboratory. The disassembled heat exchanger proved that precipitation was successfully prevented by adding CO2 to the water before heating

  19. High Temperature Aquifer Storage

    NASA Astrophysics Data System (ADS)

    Ueckert, Martina; Niessner, Reinhard; Baumann, Thomas

    2016-04-01

    Combined heat and power generation (CHP) is highly efficient because excess heat is used for heating and/or process energy. However, the demand of heat energy varies considerably throughout the year while the demand for electrical energy is rather constant. It seems economically and ecologically highly beneficial for municipalities and large power consumers such as manufacturing plants to store excess heat in groundwater aquifers and to recuperate this energy at times of higher demand. Within the project High Temperature Aquifer Storage, scientists investigate storage and recuperation of excess heat energy into the bavarian Malm aquifer. Apart from high transmissivity and favorable pressure gradients, the hydrochemical conditions are crucial for long-term operation. An enormous technical challenge is the disruption of the carbonate equilibrium - modeling results indicated a carbonate precipitation of 10 - 50 kg/d in the heat exchangers. The test included five injection pulses of hot water (60 °C up to 110 °C) and four tracer pulses, each consisting of a reactive and a conservative fluorescent dye, into a depth of about 300 m b.s.l. resp. 470 m b.s.l. Injection and production rates were 15 L/s. To achieve the desired water temperatures, about 4 TJ of heat energy were necessary. Electrical conductivity, pH and temperature were recorded at a bypass where also samples were taken. A laboratory container at the drilling site was equipped for analysing the concentration of the dyes and the major cations at sampling intervals of down to 15 minutes. Additional water samples were taken and analysed in the laboratory. The disassembled heat exchanger prooved that precipitation was successfully prevented by adding CO2 to the water before heating. Nevertheless, hydrochemical data proved both, dissolution and precipitation processes in the aquifer. This was also suggested by the hydrochemical modelling with PhreeqC and is traced back to mixture dissolution and changing

  20. High Temperature Thermoelectric Materials

    NASA Astrophysics Data System (ADS)

    Ioannidou, A. A.; Rull, M.; Martin-Gonzalez, M.; Moure, A.; Jacquot, A.; Niarchos, D.

    2014-07-01

    The use of microwave energy for materials processing has a major potential and real advantages over conventional heating such as (1) time and energy savings, (2) rapid heating rates (volumetric heating vs. conduction), (3) considerably reduced processing time and temperature, (4) fine microstructures and hence improved mechanical properties and better product performance, and (5) finally lower environmental impact. In this study, we investigated the use of microwave-assisted synthesis to synthesize a series of Co1- x Fe x Sb3 using this novel approach, which gave high quality materials with little or no impurities in a fraction of the time needed for conventional synthesis. X-ray diffraction analysis was used to examine the structure and the lattice parameters of the samples, while scanning electron microscopy with energy dispersive x-ray spectroscopy was used to study the morphology of the compounds. The samples were sintered by spark plasma sintering, and the highest ZT of 0.33 was obtained for x = 0.2 at 700 K.

  1. Synchrotron x-ray spectroscopy of EuHN O3 aqueous solutions at high temperatures and pressures and Nb-bearing silicate melt phases coexisting with hydrothermal fluids using a modified hydrothermal diamond anvil cell and rail assembly

    USGS Publications Warehouse

    Mayanovic, Robert A.; Anderson, Alan J.; Bassett, William A.; Chou, I.-Ming

    2007-01-01

    A modified hydrothermal diamond anvil cell (HDAC) rail assembly has been constructed for making synchrotron x-ray absorption spectroscopy, x-ray fluorescence, and x-ray mapping measurements on fluids or solid phases in contact with hydrothermal fluids up to ???900??C and 700 MPa. The diamond anvils of the HDAC are modified by laser milling grooves or holes, for the reduction of attenuation of incident and fluorescent x rays and sample cavities. The modified HDAC rail assembly has flexibility in design for measurement of light elements at low concentrations or heavy elements at trace levels in the sample and the capability to probe minute individual phases of a multiphase fluid-based system using focused x-ray microbeam. The supporting rail allows for uniform translation of the HDAC, rotation and tilt stages, and a focusing mirror, which is used to illuminate the sample for visual observation using a microscope, relative to the direction of the incident x-ray beam. A structure study of Eu(III) aqua ion behavior in high-temperature aqueous solutions and a study of Nb partitioning and coordination in a silicate melt in contact with a hydrothermal fluid are described as applications utilizing the modified HDAC rail assembly. ?? 2007 American Institute of Physics.

  2. High-temperature piezoelectric sensing.

    PubMed

    Jiang, Xiaoning; Kim, Kyungrim; Zhang, Shujun; Johnson, Joseph; Salazar, Giovanni

    2013-01-01

    Piezoelectric sensing is of increasing interest for high-temperature applications in aerospace, automotive, power plants and material processing due to its low cost, compact sensor size and simple signal conditioning, in comparison with other high-temperature sensing techniques. This paper presented an overview of high-temperature piezoelectric sensing techniques. Firstly, different types of high-temperature piezoelectric single crystals, electrode materials, and their pros and cons are discussed. Secondly, recent work on high-temperature piezoelectric sensors including accelerometer, surface acoustic wave sensor, ultrasound transducer, acoustic emission sensor, gas sensor, and pressure sensor for temperatures up to 1,250 °C were reviewed. Finally, discussions of existing challenges and future work for high-temperature piezoelectric sensing are presented. PMID:24361928

  3. High-Temperature Piezoelectric Sensing

    PubMed Central

    Jiang, Xiaoning; Kim, Kyungrim; Zhang, Shujun; Johnson, Joseph; Salazar, Giovanni

    2014-01-01

    Piezoelectric sensing is of increasing interest for high-temperature applications in aerospace, automotive, power plants and material processing due to its low cost, compact sensor size and simple signal conditioning, in comparison with other high-temperature sensing techniques. This paper presented an overview of high-temperature piezoelectric sensing techniques. Firstly, different types of high-temperature piezoelectric single crystals, electrode materials, and their pros and cons are discussed. Secondly, recent work on high-temperature piezoelectric sensors including accelerometer, surface acoustic wave sensor, ultrasound transducer, acoustic emission sensor, gas sensor, and pressure sensor for temperatures up to 1,250 °C were reviewed. Finally, discussions of existing challenges and future work for high-temperature piezoelectric sensing are presented. PMID:24361928

  4. Structural, magnetic and Mossbauer studies of TI doped Gd2Fe17-xTix and Gd2Fe16Ga1-xTix (0≤x≤1)

    NASA Astrophysics Data System (ADS)

    Pokharel, G.; Syed Ali, K. S.; Mishra, S. R.

    2015-05-01

    Magnetic compounds of the type Gd2Fe17-xTix and Gd2Fe16Ga1-xTix (x=0.0-1.0) were prepared by arc melting and their structural and magnetic properties were studied by X-ray diffraction (XRD), magnetometery and Mossbauer spectroscopy. The Rietveld analysis of X-ray data shows that these α-Fe free solid-solutions crystallize with Th2Ni17-type structure as main phase along with GdFe2 and TiFe2 as additional phases at higher, x≥0.5 contents. The unit cell volume expands with Ga and Ti content. The Rietveld analysis indicate that both Ti and Ga atoms prefer 12j and 12k sites in both compounds. The effect of Ti and co-substituted Ga-Ti on the bond length are quite different. The saturation magnetization Ms, at 300 K for Gd2Fe17-xTix and Gd2Fe16Ga1-xTix was found to decrease linearly with increasing Ti content. The Ms in both compounds at x=1 reduced by 9% as compared to their parent compounds at x=0. The Curie temperature, Tc, for Gd2Fe17-xTix increased from 513 K (x=0) to 544 K (x=1) while Tc for Gd2Fe16Ga1-xTix reduced from 560 (x=0) to 544 K (x=1) with increase in Ti content. Thus the observed variation in Tc follows Gd2Fe17Mossbauer results indicate decrease in hyperfine fields and increase in the isomer shifts with the increase in Ti content. Overall co-substituted Ga-Ti, Gd2Fe16Ga1-xTix show high Tc with marginal decline in saturation magnetization. Thus α-Fe free Gd2Fe16Ga1-xTix compounds can be potential candidate for high temperature permanent magnet industrial applications.

  5. High temperature suppression of dioxins.

    PubMed

    Zhan, Ming-Xiu; Chen, Tong; Fu, Jian-Ying; Lin, Xiao-Qing; Lu, Sheng-Yong; Li, Xiao-Dong; Yan, Jian-Hua; Buekens, Alfons

    2016-03-01

    Combined Sulphur-Nitrogen inhibitors, such as sewage sludge decomposition gases (SDG), thiourea and amidosulphonic acid have been observed to suppress the de novo synthesis of dioxins effectively. In this study, the inhibition of PCDD/Fs formation from model fly ash was investigated at unusually high temperatures (650 °C and 850 °C), well above the usual range of de novo tests (250-400 °C). At 650 °C it was found that SDG evolving from dried sewage sludge could suppress the formation of 2,3,7,8-substituted PCDD/Fs with high efficiency (90%), both in weight units and in I-TEQ units. Additionally, at 850 °C, three kinds of sulphur-amine or sulphur-ammonium compounds were tested to inhibit dioxins formation during laboratory-scale tests, simulating municipal solid waste incineration. The suppression efficiencies of PCDD/Fs formed through homogeneous gas phase reactions were all above 85% when 3 wt. % of thiourea (98.7%), aminosulphonic acid (96.0%) or ammonium thiosulphate (87.3%) was added. Differences in the ratio of PCDFs/PCDDs, in weight average chlorination level and in the congener distribution of the 17 toxic PCDD/Fs indicated that the three inhibitors tested followed distinct suppression pathways, possibly in relation to their different functional groups of nitrogen. Furthermore, thiourea reduced the (weight) average chlorinated level. In addition, the thermal decomposition of TUA was studied by means of thermogravimetry-fourier transform infrared spectroscopy (TG-FTIR) and the presence of SO2, SO3, NH3 and nitriles (N≡C bonds) was shown in the decomposition gases; these gaseous inhibitors might be the primary dioxins suppressants.

  6. Impurity channels of the long-lived Mossbauer effect

    PubMed Central

    Liu, Yao-Yuan; Cheng, Yao

    2015-01-01

    Recent reports have suggested that the nuclear resonant absorption of a long-lived Mossbauer state e.g., 93mNb is mediated by an entangled photon pair (biphoton) rather than by a single photon. Multipolar nuclear excitation in crystals of a single isotope with a natural abundance of 100% spreads in a region containing billions of identical nuclei. As a consequence of the delocalisation, additional decay channels via the impurities, the crystal defects, and the sample boundary, give rise to a density- and temperature-dependent decay. In this letter we report our discovery of impurity channels, the intensity of which is proportional to the square of the 93mNb density. PMID:26503613

  7. Advanced High Temperature Structural Seals

    NASA Astrophysics Data System (ADS)

    Newquist, Charles W.; Verzemnieks, Juris; Keller, Peter C.; Rorabaugh, Michael; Shorey, Mark

    2002-10-01

    This program addresses the development of high temperature structural seals for control surfaces for a new generation of small reusable launch vehicles. Successful development will contribute significantly to the mission goal of reducing launch cost for small, 200 to 300 pound payloads. Development of high temperature seals is mission enabling. For instance, ineffective control surface seals can result in high temperature (3100 F) flows in the elevon area exceeding structural material limits. Longer sealing life will allow use for many missions before replacement, contributing to the reduction of hardware, operation and launch costs.

  8. Advanced High Temperature Structural Seals

    NASA Technical Reports Server (NTRS)

    Newquist, Charles W.; Verzemnieks, Juris; Keller, Peter C.; Rorabaugh, Michael; Shorey, Mark

    2002-01-01

    This program addresses the development of high temperature structural seals for control surfaces for a new generation of small reusable launch vehicles. Successful development will contribute significantly to the mission goal of reducing launch cost for small, 200 to 300 pound payloads. Development of high temperature seals is mission enabling. For instance, ineffective control surface seals can result in high temperature (3100 F) flows in the elevon area exceeding structural material limits. Longer sealing life will allow use for many missions before replacement, contributing to the reduction of hardware, operation and launch costs.

  9. Advanced High Temperature Structural Seals

    NASA Technical Reports Server (NTRS)

    Newquist, Charles W.; Verzemnieks, Juris; Keller, Peter C.; Shorey, Mark W.; Steinetz, Bruce (Technical Monitor)

    2000-01-01

    This program addresses the development of high temperature structural seals for control surfaces for a new generation of small reusable launch vehicles. Successful development will contribute significantly to the mission goal of reducing launch cost for small, 200 to 300 lb payloads. Development of high temperature seals is mission enabling. For instance, ineffective control surface seals can result in high temperature (3100 F) flows in the elevon area exceeding structural material limits. Longer sealing life will allow use for many missions before replacement, contributing to the reduction of hardware, operation and launch costs. During the first phase of this program the existing launch vehicle control surface sealing concepts were reviewed, the aerothermal environment for a high temperature seal design was analyzed and a mock up of an arc-jet test fixture for evaluating seal concepts was fabricated.

  10. Containerless high temperature calorimeter apparatus

    NASA Technical Reports Server (NTRS)

    Lacy, L. L.; Nisen, D. B. (Inventor)

    1981-01-01

    A calorimeter apparatus for measuring high temperature thermophysical properties of materials is disclosed which includes a containerless heating apparatus in which the specimen is suspended and heated by electron bombardment.

  11. High-temperature structural intermetallics

    SciTech Connect

    Yamaguchi, M.; Inui, H.; Ito, K.

    2000-01-01

    In the last one and a half decades, a great deal of fundamental and developmental research has been made on high-temperature structural intermetallics aiming at the implementation of these intermetallics in aerospace, automotive and land-based applications. These intermetallics include aluminides formed with either titanium, nickel or iron and silicides formed with transition metals. Of these high-temperature intermetallics, TiAl-based alloys with great potential in both aerospace and automotive applications have been attracting particular attention. Recently TiAl turbocharger wheels have finally started being used for turbochargers for commercial passenger cars of a special type. The current status of the research and development of these high-temperature intermetallics is summarized and a perspective on what directions future research and development of high-temperature intermetallics should take is provided.

  12. High temperature current mirror amplifier

    DOEpatents

    Patterson, III, Raymond B.

    1984-05-22

    A high temperature current mirror amplifier having biasing means in the transdiode connection of the input transistor for producing a voltage to maintain the base-collector junction reversed-biased and a current means for maintaining a current through the biasing means at high temperatures so that the base-collector junction of the input transistor remained reversed-biased. For accuracy, a second current mirror is provided with a biasing means and current means on the input leg.

  13. 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.

  14. The Very High Temperature Reactor

    SciTech Connect

    Hans D. Gougar; David A. Petti

    2011-06-01

    The High Temperature Reactor (HTR) and Very High Temperature Reactor (VHTR) are types of nuclear power plants that, as the names imply, operate at temperatures above those of the conventional nuclear power plants that currently generate electricity in the US and other countries. Like existing nuclear plants, heat generated from the fission of uranium or plutonium atoms is carried off by a working fluid and can be used generate electricity. The very hot working fluid also enables the VHTR to drive other industrial processes that require high temperatures not achievable by conventional nuclear plants (Figure 1). For this reason, the VHTR is being considered for non-electrical energy applications. The reactor and power conversion system are constructed using special materials that make a core meltdown virtually impossible.

  15. High temperature Seebeck coefficient metrology

    SciTech Connect

    Martin, J.; Tritt, T.; Uher, C.

    2010-12-15

    We present an overview of the challenges and practices of thermoelectric metrology on bulk materials at high temperature (300 to 1300 K). The Seebeck coefficient, when combined with thermal and electrical conductivity, is an essential property measurement for evaluating the potential performance of novel thermoelectric materials. However, there is some question as to which measurement technique(s) provides the most accurate determination of the Seebeck coefficient at high temperature. This has led to the implementation of nonideal practices that have further complicated the confirmation of reported high ZT materials. To ensure meaningful interlaboratory comparison of data, thermoelectric measurements must be reliable, accurate, and consistent. This article will summarize and compare the relevant measurement techniques and apparatus designs required to effectively manage uncertainty, while also providing a reference resource of previous advances in high temperature thermoelectric metrology.

  16. Gallium phosphide high temperature diodes

    NASA Technical Reports Server (NTRS)

    Chaffin, R. J.; Dawson, L. R.

    1981-01-01

    High temperature (300 C) diodes for geothermal and other energy applications were developed. A comparison of reverse leakage currents of Si, GaAs, and GaP was made. Diodes made from GaP should be usable to 500 C. A Liquid Phase Epitaxy (LPE) process for producing high quality, grown junction GaP diodes is described. This process uses low vapor pressure Mg as a dopant which allows multiple boat growth in the same LPE run. These LPE wafers were cut into die and metallized to make the diodes. These diodes produce leakage currents below ten to the -9th power A/sq cm at 400 C while exhibiting good high temperature rectification characteristics. High temperature life test data is presented which shows exceptional stability of the V-I characteristics.

  17. High temperature current mirror amplifier

    DOEpatents

    Patterson, R.B. III.

    1984-05-22

    Disclosed is a high temperature current mirror amplifier having biasing means in the transdiode connection of the input transistor for producing a voltage to maintain the base-collector junction reversed-biased and a current means for maintaining a current through the biasing means at high temperatures so that the base-collector junction of the input transistor remained reversed-biased. For accuracy, a second current mirror is provided with a biasing means and current means on the input leg. 2 figs.

  18. High Temperature Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    1985-01-01

    These are the proceedings of the High Temperature Polymer Matrix Composites Conference held at the NASA Lewis Research Center on March 16 to 18, 1983. The purpose of the conference is to provide scientists and engineers working in the field of high temperature polymer matrix composites an opportunity to review, exchange, and assess the latest developments in this rapidly expanding area of materials technology. Technical papers are presented in the following areas: (1) matrix development; (2) adhesive development; (3) characterization; (4) environmental effects; and (5) applications.

  19. High temperature superconductor current leads

    DOEpatents

    Hull, J.R.; Poeppel, R.B.

    1995-06-20

    An electrical lead is disclosed having one end for connection to an apparatus in a cryogenic environment and the other end for connection to an apparatus outside the cryogenic environment. The electrical lead includes a high temperature superconductor wire and an electrically conductive material distributed therein, where the conductive material is present at the one end of the lead at a concentration in the range of from 0 to about 3% by volume, and at the other end of the lead at a concentration of less than about 20% by volume. Various embodiments are shown for groups of high temperature superconductor wires and sheaths. 9 figs.

  20. High temperature superconductor current leads

    DOEpatents

    Hull, John R.; Poeppel, Roger B.

    1995-01-01

    An electrical lead having one end for connection to an apparatus in a cryogenic environment and the other end for connection to an apparatus outside the cryogenic environment. The electrical lead includes a high temperature superconductor wire and an electrically conductive material distributed therein, where the conductive material is present at the one end of the lead at a concentration in the range of from 0 to about 3% by volume, and at the other end of the lead at a concentration of less than about 20% by volume. Various embodiments are shown for groups of high temperature superconductor wires and sheaths.

  1. High temperature electronic gain device

    DOEpatents

    McCormick, J. Byron; Depp, Steven W.; Hamilton, Douglas J.; Kerwin, William J.

    1979-01-01

    An integrated thermionic device suitable for use in high temperature, high radiation environments. Cathode and control electrodes are deposited on a first substrate facing an anode on a second substrate. The substrates are sealed to a refractory wall and evacuated to form an integrated triode vacuum tube.

  2. A solar high temperature kiln

    NASA Astrophysics Data System (ADS)

    Huettenhoelscher, N.; Bergmann, K.

    1981-11-01

    The feasibility of using solar energy in developing countries for baking ceramic construction materials was investigated. The solar high temperature kiln is described. It uses two parabolic concentrators which direct available radiation into the baking chamber. The Sun tracker has only one axis. Preliminary test results with the prototype kiln were satisfactory.

  3. High Temperature Transparent Furnace Development

    NASA Technical Reports Server (NTRS)

    Bates, Stephen C.

    1997-01-01

    This report describes the use of novel techniques for heat containment that could be used to build a high temperature transparent furnace. The primary objective of the work was to experimentally demonstrate transparent furnace operation at 1200 C. Secondary objectives were to understand furnace operation and furnace component specification to enable the design and construction of a low power prototype furnace for delivery to NASA in a follow-up project. The basic approach of the research was to couple high temperature component design with simple concept demonstration experiments that modify a commercially available transparent furnace rated at lower temperature. A detailed energy balance of the operating transparent furnace was performed, calculating heat losses through the furnace components as a result of conduction, radiation, and convection. The transparent furnace shells and furnace components were redesigned to permit furnace operation at at least 1200 C. Techniques were developed that are expected to lead to significantly improved heat containment compared with current transparent furnaces. The design of a thermal profile in a multizone high temperature transparent furnace design was also addressed. Experiments were performed to verify the energy balance analysis, to demonstrate some of the major furnace improvement techniques developed, and to demonstrate the overall feasibility of a high temperature transparent furnace. The important objective of the research was achieved: to demonstrate the feasibility of operating a transparent furnace at 1200 C.

  4. High temperature turbine engine structure

    DOEpatents

    Boyd, Gary L.

    1991-01-01

    A high temperature turbine engine includes a rotor portion having axially stacked adjacent ceramic rotor parts. A ceramic/ceramic joint structure transmits torque between the rotor parts while maintaining coaxial alignment and axially spaced mutually parallel relation thereof despite thermal and centrifugal cycling.

  5. High temperature turbine engine structure

    DOEpatents

    Boyd, Gary L.

    1990-01-01

    A high temperature turbine engine includes a hybrid ceramic/metallic rotor member having ceramic/metal joint structure. The disclosed joint is able to endure higher temperatures than previously possible, and aids in controlling heat transfer in the rotor member.

  6. High temperature lightweight foamed cements

    DOEpatents

    Sugama, Toshifumi.

    1989-10-03

    Cement slurries are disclosed which are suitable for use in geothermal wells since they can withstand high temperatures and high pressures. The formulation consists of cement, silica flour, water, a retarder, a foaming agent, a foam stabilizer, and a reinforcing agent. A process for producing these cements is also disclosed. 3 figs.

  7. High temperature lightweight foamed cements

    DOEpatents

    Sugama, Toshifumi

    1989-01-01

    Cement slurries are disclosed which are suitable for use in geothermal wells since they can withstand high temperatures and high pressures. The formulation consists of cement, silica flour, water, a retarder, a foaming agent, a foam stabilizer, and a reinforcing agent. A process for producing these cements is also disclosed.

  8. High-Temperature Optical Sensor

    NASA Technical Reports Server (NTRS)

    Adamovsky, Grigory; Juergens, Jeffrey R.; Varga, Donald J.; Floyd, Bertram M.

    2010-01-01

    A high-temperature optical sensor (see Figure 1) has been developed that can operate at temperatures up to 1,000 C. The sensor development process consists of two parts: packaging of a fiber Bragg grating into a housing that allows a more sturdy thermally stable device, and a technological process to which the device is subjected to in order to meet environmental requirements of several hundred C. This technology uses a newly discovered phenomenon of the formation of thermally stable secondary Bragg gratings in communication-grade fibers at high temperatures to construct robust, optical, high-temperature sensors. Testing and performance evaluation (see Figure 2) of packaged sensors demonstrated operability of the devices at 1,000 C for several hundred hours, and during numerous thermal cycling from 400 to 800 C with different heating rates. The technology significantly extends applicability of optical sensors to high-temperature environments including ground testing of engines, flight propulsion control, thermal protection monitoring of launch vehicles, etc. It may also find applications in such non-aerospace arenas as monitoring of nuclear reactors, furnaces, chemical processes, and other hightemperature environments where other measurement techniques are either unreliable, dangerous, undesirable, or unavailable.

  9. Self-propagating high-temperature synthesis of metal oxides; Reactions in external magnetic fields

    NASA Astrophysics Data System (ADS)

    Aguas, Marco Diogo

    The preparation of metal oxides by Self-Propagating High-Temperature Synthesis is reported. The reactions are started with a point source of ignition; typically a hot wire. A synthesis wave is observed moving out from the point source and reactions terminate in seconds. Products obtained can be classified into ferrites (magnetic applications) and stannates (gas sensing applications). Ferrites were synthesised under variable external magnetic fields. The synthesis wave is hotter in the presence of an external magnetic field for hard ferrite synthesis. For spinel ferrites the opposite was observed. Materials synthesised in the field show differences in their bulk magnetic properties (coercivity and saturation magnetisation), structures and microstructures. Combustion reactions in large fields revealed changes in unit cell volume (shrinkage was observed for hard ferrites while expansion was observed for spinel ferrites). SHS synthesised hard ferrites show two distinct components; one has large grain structure consisting of 50% acicular particles of 100 mum and another that has a finer microstructure. The ferrites studied were BaFe12O19, SrFe12O19, MgFe2O4, and Mg0.5Zn0.5Fe2O4. Formation of ferrites by SHS was also studied by time resolved X-ray diffraction. Patterns were successfully recorded at up to 0.8 s intervals. These showed that synthesis of ferrites is in some cases through intermediates. TRXRD has also helped form theories for the mechanistic pathways of the reactions. Work carried out has shown that magnetic fields act on SHS reactions in 3 stages; before, during and after reactions. BaSnO3 was prepared by SHS from various barium and tin reagents. Sintering of the SHS prepared powders at 800 °C for 2-72 h produced phase pure BaSnO3. Powders obtained showed sensitivity towards CO2. All products were analysed by X-ray powder diffraction, SEM/ED AX, electron microprobe, and FT-IR. The ferrites were also analysed by 57Fe Mossbauer spectroscopy, VSM, thermal

  10. Motor for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Roopnarine (Inventor)

    2013-01-01

    A high temperature motor has a stator with poles formed by wire windings, and a rotor with magnetic poles on a rotor shaft positioned coaxially within the stator. The stator and rotor are built up from stacks of magnetic-alloy laminations. The stator windings are made of high temperature magnet wire insulated with a vitreous enamel film, and the wire windings are bonded together with ceramic binder. A thin-walled cylinder is positioned coaxially between the rotor and the stator to prevent debris from the stator windings from reaching the rotor. The stator windings are wound on wire spools made of ceramic, thereby avoiding need for mica insulation and epoxy/adhesive. The stator and rotor are encased in a stator housing with rear and front end caps, and rear and front bearings for the rotor shaft are mounted on external sides of the end caps to keep debris from the motor migrating into the bearings' races.

  11. High Temperature Heat Exchanger Project

    SciTech Connect

    Anthony E. Hechanova, Ph.D.

    2008-09-30

    The UNLV Research Foundation assembled a research consortium for high temperature heat exchanger design and materials compatibility and performance comprised of university and private industry partners under the auspices of the US DOE-NE Nuclear Hydrogen Initiative in October 2003. The objectives of the consortium were to conduct investigations of candidate materials for high temperature heat exchanger componets in hydrogen production processes and design and perform prototypical testing of heat exchangers. The initial research of the consortium focused on the intermediate heat exchanger (located between the nuclear reactor and hydrogen production plan) and the components for the hydrogen iodine decomposition process and sulfuric acid decomposition process. These heat exchanger components were deemed the most challenging from a materials performance and compatibility perspective

  12. High temperature structural insulating material

    DOEpatents

    Chen, W.Y.

    1984-07-27

    A high temperature structural insulating material useful as a liner for cylinders of high temperature engines through the favorable combination of high service temperature (above about 800/sup 0/C), low thermal conductivity (below about 0.2 W/m/sup 0/C), and high compressive strength (above about 250 psi). The insulating material is produced by selecting hollow ceramic beads with a softening temperature above about 800/sup 0/C, a diameter within the range of 20-200 ..mu..m, and a wall thickness in the range of about 2 to 4 ..mu..m; compacting the beads and a compatible silicate binder composition under pressure and sintering conditions to provide the desired structural form with the structure having a closed-cell, compact array of bonded beads.

  13. High temperature structural insulating material

    DOEpatents

    Chen, Wayne Y.

    1987-01-01

    A high temperature structural insulating material useful as a liner for cylinders of high temperature engines through the favorable combination of high service temperature (above about 800.degree. C.), low thermal conductivity (below about 0.2 W/m.degree. C.), and high compressive strength (above about 250 psi). The insulating material is produced by selecting hollow ceramic beads with a softening temperature above about 800.degree. C., a diameter within the range of 20-200 .mu.m, and a wall thickness in the range of about 2-4 .mu.m; compacting the beads and a compatible silicate binder composition under pressure and sintering conditions to provide the desired structural form with the structure having a closed-cell, compact array of bonded beads.

  14. High temperature structural insulating material

    DOEpatents

    Chen, Wayne Y.

    1987-01-06

    A high temperature structural insulating material useful as a liner for cylinders of high temperature engines through the favorable combination of high service temperature (above about 800.degree. C.), low thermal conductivity (below about 0.2 W/m.degree. C.), and high compressive strength (above about 250 psi). The insulating material is produced by selecting hollow ceramic beads with a softening temperature above about 800.degree. C., a diameter within the range of 20-200 .mu.m, and a wall thickness in the range of about 2-4 .mu.m; compacting the beads and a compatible silicate binder composition under pressure and sintering conditions to provide the desired structural form with the structure having a closed-cell, compact array of bonded beads.

  15. High Temperature Solar Cell Development

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Raffaelle, Ryne P.; Merritt, Danielle

    2004-01-01

    The majority of satellites and near-earth probes developed to date have used photovoltaic arrays for power generation. If future mission to probe environments close to the sun will be able to use photovoltaic power, solar cells that can function at high temperatures, under high light intensity, and high radiation conditions must be developed. In this paper, we derive the optimum bandgap as a function of the operating temperature.

  16. High temperature solar thermal receiver

    NASA Technical Reports Server (NTRS)

    1979-01-01

    A design concept for a high temperature solar thermal receiver to operate at 3 atmospheres pressure and 2500 F outlet was developed. The performance and complexity of windowed matrix, tube-header, and extended surface receivers were evaluated. The windowed matrix receiver proved to offer substantial cost and performance benefits. An efficient and cost effective hardware design was evaluated for a receiver which can be readily interfaced to fuel and chemical processes or to heat engines for power generation.

  17. HIGH TEMPERATURE MICROSCOPE AND FURNACE

    DOEpatents

    Olson, D.M.

    1961-01-31

    A high-temperature microscope is offered. It has a reflecting optic situated above a molten specimen in a furnace and reflecting the image of the same downward through an inert optic member in the floor of the furnace, a plurality of spaced reflecting plane mirrors defining a reflecting path around the furnace, a standard microscope supported in the path of and forming the end terminus of the light path.

  18. Containerless high-temperature calorimeter

    NASA Technical Reports Server (NTRS)

    Lacy, L. L.; Nisen, D. B.; Robinson, M. B.

    1979-01-01

    Samples are heated by electron bombardment in high-temperature calorimeter that operates from 1,000 to 3,600 C yet consumes less that 100 watts at temperatures less than 2,500 C. Contamination of samples is kept to minimum by suspending them from wire in vacuum chamber. Various sample slopes such as wires, dishs, spheres, rods, or irregular bodies can be accommodated and only about 100 nq of samples are needed for accurate measurements.

  19. High temperature turbine engine structure

    DOEpatents

    Carruthers, William D.; Boyd, Gary L.

    1993-01-01

    A high temperature ceramic/metallic turbine engine includes a metallic housing which journals a rotor member of the turbine engine. A ceramic disk-like shroud portion of the engine is supported on the metallic housing portion and maintains a close running clearance with the rotor member. A ceramic spacer assembly maintains the close running clearance of the shroud portion and rotor member despite differential thermal movements between the shroud portion and metallic housing portion.

  20. High temperature turbine engine structure

    DOEpatents

    Carruthers, William D.; Boyd, Gary L.

    1994-01-01

    A high temperature ceramic/metallic turbine engine includes a metallic housing which journals a rotor member of the turbine engine. A ceramic disk-like shroud portion of the engine is supported on the metallic housing portion and maintains a close running clearance with the rotor member. A ceramic spacer assembly maintains the close running clearance of the shroud portion and rotor member despite differential thermal movements between the shroud portion and metallic housing portion.

  1. High temperature turbine engine structure

    DOEpatents

    Carruthers, William D.; Boyd, Gary L.

    1992-01-01

    A high temperature ceramic/metallic turbine engine includes a metallic housing which journals a rotor member of the turbine engine. A ceramic disk-like shroud portion of the engine is supported on the metallic housing portion and maintains a close running clearance with the rotor member. A ceramic spacer assembly maintains the close running clearance of the shroud portion and rotor member despite differential thermal movements between the shroud portion and metallic housing portion.

  2. High-temperature geothermal cableheads

    SciTech Connect

    Coquat, J.A.; Eifert, R.W.

    1981-11-01

    Two high-temperature, corrosion-resistant logging cableheads which use metal seals and a stable fluid to achieve proper electrical terminations and cable-sonde interfacings are described. A tensile bar provides a calibrated yield point, and a cone assembly anchors the cable armor to the head. Electrical problems of the sort generally ascribable to the cable-sonde interface were absent during demonstration hostile-environment loggings in which these cableheads were used.

  3. Mossbauer effect in the ion-implanted iron-carbon alloys

    NASA Technical Reports Server (NTRS)

    Han, K. S.

    1976-01-01

    The concentration dependence of Mossbauer effect in four carbon ion-implanted iron absorbers, which contain carbon as the solute atoms, has been investigated over the range of concentration 0.05 through 1 atomic percent. The specimens were prepared by implanting carbon atoms on each reference iron foil with four different bombarding energies of 250 keV, 160 keV, 140 keV and 80 keV, respectively. Thus, the specimen contains a uniform dosage of carbon atoms which penetrated up to 3,000 A depth of the reference iron. In the measurement of Mossbauer spectra, the backscattering conversion electron counting geometry was used. Typical results of Mossbauer parameters of iron-carbon alloys show that the isomer shift, quadrupole shift, the effective hyperfine splitting of Fe-57, and the intensity ratio exhibit a large variation with the increase of carbon concentration in the environment of iron atoms.

  4. High temperature thermoelectric energy conversion

    NASA Technical Reports Server (NTRS)

    Wood, Charles

    1987-01-01

    The theory and current status of materials research for high-temperature thermoelectric energy conversion are reviewed. Semiconductors are shown to be the preferred class of materials for this application. Optimization of the figure of merit of both broadband and narrow-band semiconductors is discussed as a function of temperature. Phonon scattering mechanisms are discussed, and basic material guidelines are given for reduction of thermal conductivity. Two general classes of materials show promise for high temperature figure of merit (Z) values, namely the rare earth chalcogenides and the boron-rich borides. The electronic transport properties of the rare earth chalcogenides are explicable on the basis of degenerate or partially degenerate n-type semiconductors. Boron and boron-rich borides exhibit p-type hopping conductivity, with detailed explanations proposed for the transport differing from compound to compound. Some discussion is presented on the reasons for the low thermal conductivities in these materials. Also, ZTs greater than one appear to have been realized at high temperature in many of these compounds.

  5. Ordering and oxygen content effects in YBa sub 2 (Cu sub 1 minus x Fe sub x ) sub 3 O sub 7 samples observed by high-temperature Moessbauer spectroscopy

    SciTech Connect

    Saitovitch, E.B.; Scorzelli, R.B.; Azevedo, I.S.; dos Santos, C.A. )

    1990-05-01

    We report here {ital in} {ital situ} high-temperature {sup 57}Fe Moessbauer measurements on YBa{sub 2}(Cu{sub 1{minus}{ital x}}Fe{sub {ital x}}){sub 3}O{sub 7} samples in controlled oxygen atmosphere, in air, or in vacuum. In these conditions, fundamental information can be obtained related to the thermal stability of the different Fe species, as well as the mechanism of oxygen loss.

  6. "Green" High-Temperature Polymers

    NASA Technical Reports Server (NTRS)

    Meador, Michael A.

    1998-01-01

    PMR-15 is a processable, high-temperature polymer developed at the NASA Lewis Research Center in the 1970's principally for aeropropulsion applications. Use of fiber-reinforced polymer matrix composites in these applications can lead to substantial weight savings, thereby leading to improved fuel economy, increased passenger and payload capacity, and better maneuverability. PMR-15 is used fairly extensively in military and commercial aircraft engines components seeing service temperatures as high as 500 F (260 C), such as the outer bypass duct for the F-404 engine. The current world-wide market for PMR-15 materials (resins, adhesives, and composites) is on the order of $6 to 10 million annually.

  7. High temperature sealed electrochemical cell

    SciTech Connect

    Valentin Chung, Brice Hoani; Burke, Paul J.; Sadoway, Donald R.

    2015-10-06

    A cell for high temperature electrochemical reactions is provided. The cell includes a container, at least a portion of the container acting as a first electrode. An extension tube has a first end and a second end, the extension tube coupled to the container at the second end forming a conduit from the container to said first end. A second electrode is positioned in the container and extends out of the container via the conduit. A seal is positioned proximate the first end of the extension tube, for sealing the cell.

  8. Passivation of high temperature superconductors

    NASA Technical Reports Server (NTRS)

    Vasquez, Richard P. (Inventor)

    1991-01-01

    The surface of high temperature superconductors such as YBa2Cu3O(7-x) are passivated by reacting the native Y, Ba and Cu metal ions with an anion such as sulfate or oxalate to form a surface film that is impervious to water and has a solubility in water of no more than 10(exp -3) M. The passivating treatment is preferably conducted by immersing the surface in dilute aqueous acid solution since more soluble species dissolve into the solution. The treatment does not degrade the superconducting properties of the bulk material.

  9. High temperature sorbents for oxygen

    NASA Technical Reports Server (NTRS)

    Sharma, Pramod K. (Inventor)

    1994-01-01

    A sorbent capable of removing trace amounts of oxygen (ppt) from a gas stream at a high temperature above 200 C comprising a porous alumina silicate support, such as zeolite, containing from 1 to 10 percent by weight of ion exchanged transition metal, such as copper or cobalt ions, and 0.05 to 1.0 percent by weight of an activator selected from a platinum group metal such as platinum is described. The activation temperature, oxygen sorption, and reducibility are all improved by the presence of the platinum activator.

  10. High Temperature Sorbents for Oxygen

    NASA Technical Reports Server (NTRS)

    Sharma, Pramod K. (Inventor)

    1996-01-01

    A sorbent capable of removing trace amounts of oxygen (ppt) from a gas stream at a high temperature above 200 C is introduced. The sorbent comprises a porous alumina silicate support such as zeolite containing from 1 to 10 percent by weight of ion exchanged transition metal such as copper or cobalt ions and 0.05 to 1.0 percent by weight of an activator selected from a platinum group metal such as platinum. The activation temperature, oxygen sorption and reducibility are all improved by the presence of the platinum activator.

  11. High temperature structural sandwich panels

    NASA Astrophysics Data System (ADS)

    Papakonstantinou, Christos G.

    High strength composites are being used for making lightweight structural panels that are being employed in aerospace, naval and automotive structures. Recently, there is renewed interest in use of these panels. The major problem of most commercial available sandwich panels is the fire resistance. A recently developed inorganic matrix is investigated for use in cases where fire and high temperature resistance are necessary. The focus of this dissertation is the development of a fireproof composite structural system. Sandwich panels made with polysialate matrices have an excellent potential for use in applications where exposure to high temperatures or fire is a concern. Commercial available sandwich panels will soften and lose nearly all of their compressive strength temperatures lower than 400°C. This dissertation consists of the state of the art, the experimental investigation and the analytical modeling. The state of the art covers the performance of existing high temperature composites, sandwich panels and reinforced concrete beams strengthened with Fiber Reinforced Polymers (FRP). The experimental part consists of four major components: (i) Development of a fireproof syntactic foam with maximum specific strength, (ii) Development of a lightweight syntactic foam based on polystyrene spheres, (iii) Development of the composite system for the skins. The variables are the skin thickness, modulus of elasticity of skin and high temperature resistance, and (iv) Experimental evaluation of the flexural behavior of sandwich panels. Analytical modeling consists of a model for the flexural behavior of lightweight sandwich panels, and a model for deflection calculations of reinforced concrete beams strengthened with FRP subjected to fatigue loading. The experimental and analytical results show that sandwich panels made with polysialate matrices and ceramic spheres do not lose their load bearing capability during severe fire exposure, where temperatures reach several

  12. High temperature intermetallic binders for HVOF carbides

    SciTech Connect

    Shaw, K.G.; Gruninger, M.F.; Jarosinski, W.J.

    1994-12-31

    Gas turbines technology has a long history of employing the desirable high temperature physical attributes of ceramic-metallic (cermet) materials. The most commonly used coatings incorporate combinations of WC-Co and Cr{sub 3}C{sub 2}-NiCr, which have also been successfully utilized in other non-turbine coating applications. Increased turbine operating temperatures and other high temperature service conditions have made apparent the attractive notion of increasing the temperature capability and corrosion resistance of these coatings. In this study the intermetallic binder NiAl has been used to replace the cobalt and NiCr constituents of conventional WC and Cr{sub 3}C{sub 2} cermet powders. The composite carbide thermal spray powders were fabricated for use in the HVOF coating process. The structure of HVOF deposited NiAl-carbide coatings are compared directly to the more familiar WC-Co and Cr{sub 3}C{sub 2}-NiCr coatings using X-ray diffraction, back-scattered electron imaging (BEI) and electron dispersive spectroscopy (EDS). Hardness variations with temperature are reported and compared between the NiAl and Co/NiCr binders.

  13. High temperature PEM fuel cells

    NASA Astrophysics Data System (ADS)

    Zhang, Jianlu; Xie, Zhong; Zhang, Jiujun; Tang, Yanghua; Song, Chaojie; Navessin, Titichai; Shi, Zhiqing; Song, Datong; Wang, Haijiang; Wilkinson, David P.; Liu, Zhong-Sheng; Holdcroft, Steven

    There are several compelling technological and commercial reasons for operating H 2/air PEM fuel cells at temperatures above 100 °C. Rates of electrochemical kinetics are enhanced, water management and cooling is simplified, useful waste heat can be recovered, and lower quality reformed hydrogen may be used as the fuel. This review paper provides a concise review of high temperature PEM fuel cells (HT-PEMFCs) from the perspective of HT-specific materials, designs, and testing/diagnostics. The review describes the motivation for HT-PEMFC development, the technology gaps, and recent advances. HT-membrane development accounts for ∼90% of the published research in the field of HT-PEMFCs. Despite this, the status of membrane development for high temperature/low humidity operation is less than satisfactory. A weakness in the development of HT-PEMFC technology is the deficiency in HT-specific fuel cell architectures, test station designs, and testing protocols, and an understanding of the underlying fundamental principles behind these areas. The development of HT-specific PEMFC designs is of key importance that may help mitigate issues of membrane dehydration and MEA degradation.

  14. NSTX High Temperature Sensor Systems

    SciTech Connect

    B.McCormack; H.W. Kugel; P. Goranson; R. Kaita; et al

    1999-11-01

    The design of the more than 300 in-vessel sensor systems for the National Spherical Torus Experiment (NSTX) has encountered several challenging fusion reactor diagnostic issues involving high temperatures and space constraints. This has resulted in unique miniature, high temperature in-vessel sensor systems mounted in small spaces behind plasma facing armor tiles, and they are prototypical of possible high power reactor first-wall applications. In the Center Stack, Divertor, Passive Plate, and vessel wall regions, the small magnetic sensors, large magnetic sensors, flux loops, Rogowski Coils, thermocouples, and Langmuir Probes are qualified for 600 degrees C operation. This rating will accommodate both peak rear-face graphite tile temperatures during operations and the 350 degrees C bake-out conditions. Similar sensor systems including flux loops, on other vacuum vessel regions are qualified for 350 degrees C operation. Cabling from the sensors embedded in the graphite tiles follows narrow routes to exit the vessel. The detailed sensor design and installation methods of these diagnostic systems developed for high-powered ST operation are discussed.

  15. High temperature catalytic membrane reactors

    SciTech Connect

    Not Available

    1990-03-01

    Current state-of-the-art inorganic oxide membranes offer the potential of being modified to yield catalytic properties. The resulting modules may be configured to simultaneously induce catalytic reactions with product concentration and separation in a single processing step. Processes utilizing such catalytically active membrane reactors have the potential for dramatically increasing yield reactions which are currently limited by either thermodynamic equilibria, product inhibition, or kinetic selectivity. Examples of commercial interest include hydrogenation, dehydrogenation, partial and selective oxidation, hydrations, hydrocarbon cracking, olefin metathesis, hydroformylation, and olefin polymerization. A large portion of the most significant reactions fall into the category of high temperature, gas phase chemical and petrochemical processes. Microporous oxide membranes are well suited for these applications. A program is proposed to investigate selected model reactions of commercial interest (i.e. dehydrogenation of ethylbenzene to styrene and dehydrogenation of butane to butadiene) using a high temperature catalytic membrane reactor. Membranes will be developed, reaction dynamics characterized, and production processes developed, culminating in laboratory-scale demonstration of technical and economic feasibility. As a result, the anticipated increased yield per reactor pass economic incentives are envisioned. First, a large decrease in the temperature required to obtain high yield should be possible because of the reduced driving force requirement. Significantly higher conversion per pass implies a reduced recycle ratio, as well as reduced reactor size. Both factors result in reduced capital costs, as well as savings in cost of reactants and energy.

  16. Pigmenting agents in Martian soils: inferences from spectral, Mossbauer, and magnetic properties of nanophase and other iron oxides in Hawaiian palagonitic soil PN-9.

    PubMed

    Morris, R V; Golden, D C; Bell JF 3rd; Lauer, H V; Adams, J B

    1993-10-01

    We have examined a Hawaiian palagonitic tephra sample (PN-9) that has spectroscopic similarities to Martian bright regions using a number of analytical techniques, including Mossbauer and reflectance spectroscopy, X-ray diffraction, instrumental neutron activation analysis, electron probe microanalysis, transmission electron microscopy, and dithionite-citrate-bicarbonate extraction. Chemically, PN-9 has a Hawaiitic composition with alkali (and presumably silica) loss resulting from leaching by meteoric water during palagonitization; no Ce anomaly is present in the REE pattern. Mineralogically, our results show that nanophase ferric oxide (np-Ox) particles (either nanophase hematite (np-Hm) or a mixture of ferrihydrite and np-Hm) are responsible for the distinctive ferric doublet and visible-wavelength ferric absorption edge observed in Mossbauer and reflectivity spectra, respectively, for this and other spectrally similar palagonitic samples. The np-Ox particles appear to be imbedded in a hydrated aluminosilicate matrix material; no evidence was found for phyllosilicates. Other iron-bearing phases observed are titanomagnetite, which accounts for the magnetic nature of the sample; olivine; pyroxene; and glass. By analogy, np-Ox is likely the primary pigmenting agent of the bright soils and dust of Mars.

  17. Pigmenting agents in Martian soils: inferences from spectral, Mossbauer, and magnetic properties of nanophase and other iron oxides in Hawaiian palagonitic soil PN-9

    NASA Technical Reports Server (NTRS)

    Morris, R. V.; Golden, D. C.; Lauer, H. V. Jr; Adams, J. B.

    1993-01-01

    We have examined a Hawaiian palagonitic tephra sample (PN-9) that has spectroscopic similarities to Martian bright regions using a number of analytical techniques, including Mossbauer and reflectance spectroscopy, X-ray diffraction, instrumental neutron activation analysis, electron probe microanalysis, transmission electron microscopy, and dithionite-citrate-bicarbonate extraction. Chemically, PN-9 has a Hawaiitic composition with alkali (and presumably silica) loss resulting from leaching by meteoric water during palagonitization; no Ce anomaly is present in the REE pattern. Mineralogically, our results show that nanophase ferric oxide (np-Ox) particles (either nanophase hematite (np-Hm) or a mixture of ferrihydrite and np-Hm) are responsible for the distinctive ferric doublet and visible-wavelength ferric absorption edge observed in Mossbauer and reflectivity spectra, respectively, for this and other spectrally similar palagonitic samples. The np-Ox particles appear to be imbedded in a hydrated aluminosilicate matrix material; no evidence was found for phyllosilicates. Other iron-bearing phases observed are titanomagnetite, which accounts for the magnetic nature of the sample; olivine; pyroxene; and glass. By analogy, np-Ox is likely the primary pigmenting agent of the bright soils and dust of Mars.

  18. Compensated High Temperature Strain Gage

    NASA Technical Reports Server (NTRS)

    1994-01-01

    A device for measuring strain in substrates at high temperatures in which the thermally induced apparent strain is nulled is described. Two gages are used, one active gage and one compensating gage. Both gages are placed on the substrate to be gaged; the active gage is attached such that it responds to mechanical and thermally induced apparent strain while the compensating gage is attached such that it does not respond to mechanical strain and and measures only thermally induced apparent strain. A thermal blanket is placed over the two gages to maintain the gages at the same temperature. The two gages are wired as adjacent arms of a wheatstone bridge which nulls the thermally induced apparent strain giving a true reading of the mechanical strain in the substrate.

  19. High Temperature Transfer Molding Resins

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Smith, Joseph G., Jr. (Inventor); Hergenrother, Paul M. (Inventor)

    2000-01-01

    High temperature resins containing phenylethynyl groups that are processable by transfer molding have been prepared. These phenylethynyl containing oligomers were prepared from aromatic diamines containing phenylethynyl groups and various ratios of phthalic anhydride and 4-phenylethynlphthalic anhydride in glacial acetic acid to form a mixture of imide compounds in one step. This synthetic approach is advantageous since the products are a mixture of compounds and consequently exhibit a relatively low melting temperature. In addition, these materials exhibit low melt viscosities which are stable for several hours at 210-275 C, and since the thermal reaction of the phenylethynyl group does not occur to any appreciable extent at temperatures below 300 C, these materials have a broad processing window. Upon thermal cure at approximately 300-350 C, the phenylethynyl groups react to provide a crosslinked resin system. These new materials exhibit excellent properties and are potentially useful as adhesives, coatings, films, moldings and composite matrices.

  20. High temperature seal test rig

    NASA Technical Reports Server (NTRS)

    Addy, Harold E., Jr.

    1994-01-01

    The High Temperature Seals Test Rig Program at NASA's Lewis Research Center is a joint effort involving three separate federal government agencies. Testing has been underway at Lewis in this test rig since April, 1993. The rig was designed to run tests at temperatures to 800 F at pressures to 200 psia or at temperatures to 1300 to 1500 F at pressures to 65 psia. It was designed to run at speeds of up to 50,000 rpm which, for a 5.1 inch diameter disk, is a surface speed of about 1100 ft./sec. The rig was designed to allow easy replacement of the disks as well as the seals such that different disk materials and coatings may be tested.

  1. Faraday imaging at high temperatures

    DOEpatents

    Hackel, Lloyd A.; Reichert, Patrick

    1997-01-01

    A Faraday filter rejects background light from self-luminous thermal objects, but transmits laser light at the passband wavelength, thus providing an ultra-narrow optical bandpass filter. The filter preserves images so a camera looking through a Faraday filter at a hot target illuminated by a laser will not see the thermal radiation but will see the laser radiation. Faraday filters are useful for monitoring or inspecting the uranium separator chamber in an atomic vapor laser isotope separation process. Other uses include viewing welds, furnaces, plasma jets, combustion chambers, and other high temperature objects. These filters are can be produced at many discrete wavelengths. A Faraday filter consists of a pair of crossed polarizers on either side of a heated vapor cell mounted inside a solenoid.

  2. Faraday imaging at high temperatures

    DOEpatents

    Hackel, L.A.; Reichert, P.

    1997-03-18

    A Faraday filter rejects background light from self-luminous thermal objects, but transmits laser light at the passband wavelength, thus providing an ultra-narrow optical bandpass filter. The filter preserves images so a camera looking through a Faraday filter at a hot target illuminated by a laser will not see the thermal radiation but will see the laser radiation. Faraday filters are useful for monitoring or inspecting the uranium separator chamber in an atomic vapor laser isotope separation process. Other uses include viewing welds, furnaces, plasma jets, combustion chambers, and other high temperature objects. These filters are can be produced at many discrete wavelengths. A Faraday filter consists of a pair of crossed polarizers on either side of a heated vapor cell mounted inside a solenoid. 3 figs.

  3. Ultra-High Temperature Ceramics

    NASA Technical Reports Server (NTRS)

    Rasky, Dan; Bull, Jeff

    1994-01-01

    Recent developments in ultra-high temperature ceramic composites, and their application to advanced vehicle thermal protection systems will be discussed. Research and testing of refractory ceramics has resulted in the identification of a new family of ceramic composites that promise temperature performance to 4000 F+, significantly beyond the current state-of-the-art of reusable systems which are limited to approximately 300 F. This new family of materials includes zirconium and hafnium diboride composites with various reinforcements, such as fibers and particulates. Preliminary material characterization and testing results, including plasma arc-jet testing of prototype vehicle components, will be described. Future directions for the research and material development activities will also be discussed.

  4. High-temperature-measuring device

    DOEpatents

    Not Available

    1981-01-27

    A temperature measuring device for very high design temperatures (to 2000/sup 0/C) is described. The device comprises a homogenous base structure preferably in the form of a sphere or cylinder. The base structure contains a large number of individual walled cells. The base structure has a decreasing coefficient of elasticity within the temperature range being monitored. A predetermined quantity of inert gas is confined within each cell. The cells are dimensonally stable at the normal working temperature of the device. Increases in gaseous pressure within the cells will permanently deform the cell walls at temperatures within the high temperature range to be measured. Such deformation can be correlated to temperature by calibrating similarly constructed devices under known time and temperature conditions.

  5. High temperature polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Meador, Michael A.

    1987-01-01

    With the increased emphasis on high performance aircraft the need for lightweight, thermal/oxidatively stable materials is growing. Because of their ease of fabrication, high specific strength, and ability to be tailored chemically to produce a variety of mechanical and physical properties, polymers and polymer matrix composites present themselves as attractive materials for a number of aeropropulsion applications. In the early 1970s researchers at the NASA Lewis Research Center developed a highly processable, thermally stable (600 F) polyimide, PMR-15. Since that time, PMR-15 has become commercially available and has found use in military aircraft, in particular, the F-404 engine for the Navy's F/A-18 strike fighter. The NASA Lewis'contributions to high temperature polymer matrix composite research will be discussed as well as current and future directions.

  6. High-temperature battery calorimeter

    SciTech Connect

    Hansen, L.D.; Hart, R.H.; Chen, D.M.; Gibbard, H.F.

    1982-04-01

    A battery calorimeter was built for the measurement of thermal energy generation of high-temperature lithium--aluminum/iron sulfide battery cells, which are under development for electric vehicle propulsion and other energy storage applications. The calorimeter was designed with a temperature range of 400 /sup 0/--500 /sup 0/C, a detection limit of 1 mW, and an upper limit of heat flow of 50 W. The results of measurements on 200-Ah LiAl/FeS cells were in excellent agreement with the predictions of thermodynamic calculations based on precise measurements of the total cell polarization and the temperature coefficient of the emf. Details of the construction and operation principles of this calorimeter are given.

  7. High Temperature Particle Filtration Technology

    SciTech Connect

    Besmann, T.M.

    2001-11-13

    High temperature filtration can serve to improve the economic, environmental, and energy performance of chemical processes. This project was designed to evaluate the stability of filtration materials in the environments of the production of dimethyldichlorosilane (DDS). In cooperation with Dow Corning, chemical environments for the fluidized bed reactor where silicon is converted to DDS and the incinerator where vents are cornbusted were characterized. At Oak Ridge National Laboratory (ORNL) an exposure system was developed that could simulate these two environments. Filter samples obtained from third parties were exposed to the environments for periods up to 1000 hours. Mechanical properties before and after exposure were determined by burst-testing rings of filter material. The results indicated that several types of filter materials would likely perform well in the fluid bed environment, and two materials would be good candidates for the incinerator environment.

  8. High temperature control rod assembly

    DOEpatents

    Vollman, Russell E.

    1991-01-01

    A high temperature nuclear control rod assembly comprises a plurality of substantially cylindrical segments flexibly joined together in succession by ball joints. The segments are made of a high temperature graphite or carbon-carbon composite. The segment includes a hollow cylindrical sleeve which has an opening for receiving neutron-absorbing material in the form of pellets or compacted rings. The sleeve has a threaded sleeve bore and outer threaded surface. A cylindrical support post has a threaded shaft at one end which is threadably engaged with the sleeve bore to rigidly couple the support post to the sleeve. The other end of the post is formed with a ball portion. A hollow cylindrical collar has an inner threaded surface engageable with the outer threaded surface of the sleeve to rigidly couple the collar to the sleeve. the collar also has a socket portion which cooperates with the ball portion to flexibly connect segments together to form a ball and socket-type joint. In another embodiment, the segment comprises a support member which has a threaded shaft portion and a ball surface portion. The threaded shaft portion is engageable with an inner threaded surface of a ring for rigidly coupling the support member to the ring. The ring in turn has an outer surface at one end which is threadably engageably with a hollow cylindrical sleeve. The other end of the sleeve is formed with a socket portion for engagement with a ball portion of the support member. In yet another embodiment, a secondary rod is slidably inserted in a hollow channel through the center of the segment to provide additional strength. A method for controlling a nuclear reactor utilizing the control rod assembly is also included.

  9. Solute strengthening at high temperatures

    NASA Astrophysics Data System (ADS)

    Leyson, G. P. M.; Curtin, W. A.

    2016-08-01

    The high temperature behavior of solute strengthening has previously been treated approximately using various scaling arguments, resulting in logarithmic and power-law scalings for the stress-dependent energy barrier Δ E(τ ) versus stress τ. Here, a parameter-free solute strengthening model is extended to high temperatures/low stresses without any a priori assumptions on the functional form of Δ E(τ ) . The new model predicts that the well-established low-temperature, with energy barrier Δ {{E}\\text{b}} and zero temperature flow stress {τy0} , transitions to a near-logarithmic form for stresses in the regime 0.2<τ /{τy0}≤slant 0.5 and then transitions to a power-law form at even lower stresses τ /{τy0}<0.03 . Δ {{E}\\text{b}} and {τy0} remains as the reference energy and stress scales over the entire range of stresses. The model is applied to literature data on solution strengthening in Cu alloys and captures the experimental results quantitatively and qualitatively. Most importantly, the model accurately captures the transition in strength from the low-temperature to intermediate-temperature and the associated transition for the activation volume. Overall, the present analysis unifies the different qualitative models in the literature and, when coupled with the previous parameter-free solute strengthening model, provides a single predictive model for solute strengthening as a function of composition, temperature, and strain rate over the full range of practical utility.

  10. High temperature jet fuel stabilizers

    SciTech Connect

    Yoon, E.M.; Selvaraj, L.; Stallman, J.B.

    1996-10-01

    We have previously discussed the rationale for development of jet fuels with enhanced thermal stability at temperatures above 400{degrees}C. At these temperatures we are encroaching into the so-called pyrolysis regime, where the cleavage of carbon-carbon bonds into free radicals is facile and leads to the rapid degradation of aliphatic hydrocarbons. Notwithstanding, we established that the formation of carbonaceous materials is significantly retarded in hydrocarbon mixtures containing molecules such as benzyl alcohol (BzOH). It was ascertained that BzOH acts as a hydrogen donor capping aliphatic radicals formed at temperatures > 400{degrees}C while transforming into relatively stable products. These results suggested is superior high temperature thermal stabilizers might be found among the more conventional hydrogen donors that find application in coal liquefaction and similar hydrogenation processes. Here we present the results of {open_quotes}screening{close_quotes} and kinetic studies of traditional hydrogen donors, such as tetralin, tetrahydroquinoline and the like, together with simple derivatives designed to test the importance of specific factors in the thermal stabilization of jet fuels.

  11. High Temperature Superconducting Underground Cable

    SciTech Connect

    Farrell, Roger, A.

    2010-02-28

    The purpose of this Project was to design, build, install and demonstrate the technical feasibility of an underground high temperature superconducting (HTS) power cable installed between two utility substations. In the first phase two HTS cables, 320 m and 30 m in length, were constructed using 1st generation BSCCO wire. The two 34.5 kV, 800 Arms, 48 MVA sections were connected together using a superconducting joint in an underground vault. In the second phase the 30 m BSCCO cable was replaced by one constructed with 2nd generation YBCO wire. 2nd generation wire is needed for commercialization because of inherent cost and performance benefits. Primary objectives of the Project were to build and operate an HTS cable system which demonstrates significant progress towards commercial progress and addresses real world utility concerns such as installation, maintenance, reliability and compatibility with the existing grid. Four key technical areas addressed were the HTS cable and terminations (where the cable connects to the grid), cryogenic refrigeration system, underground cable-to-cable joint (needed for replacement of cable sections) and cost-effective 2nd generation HTS wire. This was the world’s first installation and operation of an HTS cable underground, between two utility substations as well as the first to demonstrate a cable-to-cable joint, remote monitoring system and 2nd generation HTS.

  12. High temperature two component explosive

    DOEpatents

    Mars, James E.; Poole, Donald R.; Schmidt, Eckart W.; Wang, Charles

    1981-01-01

    A two component, high temperature, thermally stable explosive composition comprises a liquid or low melting oxidizer and a liquid or low melting organic fuel. The oxidizer and fuel in admixture are incapable of substantial spontaneous exothermic reaction at temperatures on the order of 475.degree. K. At temperatures on the order of 475.degree. K., the oxidizer and fuel in admixture have an activation energy of at least about 40 kcal/mol. As a result of the high activation energy, the preferred explosive compositions are nondetonable as solids at ambient temperature, and become detonable only when heated beyond the melting point. Preferable oxidizers are selected from alkali or alkaline earth metal nitrates, nitrites, perchlorates, and/or mixtures thereof. Preferred fuels are organic compounds having polar hydrophilic groups. The most preferred fuels are guanidinium nitrate, acetamide and mixtures of the two. Most preferred oxidizers are eutectic mixtures of lithium nitrate, potassium nitrate and sodium nitrate, of sodium nitrite, sodium nitrate and potassium nitrate, and of potassium nitrate, calcium nitrate and sodium nitrate.

  13. Sialons as high temperature insulators

    NASA Technical Reports Server (NTRS)

    Phillips, W. M.; Kuo, Y. S.

    1978-01-01

    Sialons were evaluated for application as high temperature electrical insulators in contact with molybdenum and tungsten components in hard vacuum applications. Both D.C. and variable frequency A.C. resistivity data indicate the sialons to have electrical resistivity similar to common oxide in the 1000 C or higher range. Metallographic evaluations indicate good bonding of the type 15R ALN polytype to molybdenum and tungsten. The beta prime or modified silicon nitride phase was unacceptable in terms of vacuum stability. Additives effect on electrical resistivity. Similar resistivity decreases were produced by additions of molybdenum or tungsten to form cermets. The use of hot pressing at 1800 C with ALN, Al2 O3 and Si3N4 starting powders produced a better product than did a combination of SiO2 and AIN staring powders. It was indicated that sialons will be suitable insulators in the 1600K range in contact with molybdenum or tungsten if they are produced as a pure ceramic and subsequently bonded to the metal components at temperatures in the 1600K range.

  14. High-temperature containerless calorimeter

    NASA Technical Reports Server (NTRS)

    Robinson, M. B.; Lacy, L. L.

    1985-01-01

    A high-temperature (greater than 1500 K) containerless calorimeter is described and its usefulness demonstrated. The calorimeter uses the technique of omnidirectional electron bombardment of pendant drops to achieve an isothermal test environment. The small heat input into the sample (i.e., 15-50 W) can be controlled and measured. The apparatus can be used to determine the total hemispherical emissivity, specific heat, heat of fusion, surface tension, and equilibrium melting temperature of small molten drops in the temperature range of 1500 to 3500 K. The total hemispherical emissivity and specific heat of pure niobium and two alloys of niobium-germanium have been measured in the temperature range of 1700 to 2400 K. As reported in the literature, the total hemispherical emissivity varied as a function of temperature. However, specific heat values for both the pure metal and alloys seem to be independent of temperature. Specific heat for the liquid alloy phase was also measured and compared to the solid phase.

  15. Bellows high temperature cycle life

    SciTech Connect

    Broyles, R.K.

    1995-11-01

    In most cases, the bellows elements in an expansion joint are separated or insulated from the hot flow stream and have an actual bellows metal temperature (ABMT) that is much lower than the flow stream temperature. However, when the bellows are externally insulated or when the expansion joint is located inside a hot vessel, the ABMT can be very high. For these situations, the effects of temperature on bellows cycle life should be carefully considered. The design equations presented in the Standards of the expansion Joint Manufacturers Association (EJMA), ASME Section 8, Division 1, and ASME B31.3 do not currently provide cycle life equations or temperature correction factors for bellows operating in the creep temperature range. Therefore, a method is proposed which is specifically tailored to bellows for the estimation of high temperature cycle life based upon available test results. Data is also presented which demonstrates the effect of temperatures above and below 800 F on the cycle life of various bellows materials.

  16. High-temperature thermocouples and related methods

    DOEpatents

    Rempe, Joy L.; Knudson, Darrell L.; Condie, Keith G.; Wilkins, S. Curt

    2011-01-18

    A high-temperature thermocouple and methods for fabricating a thermocouple capable of long-term operation in high-temperature, hostile environments without significant signal degradation or shortened thermocouple lifetime due to heat induced brittleness.

  17. High temperature power electronics for space

    NASA Technical Reports Server (NTRS)

    Hammoud, Ahmad N.; Baumann, Eric D.; Myers, Ira T.; Overton, Eric

    1991-01-01

    A high temperature electronics program at NASA Lewis Research Center focuses on dielectric and insulating materials research, development and testing of high temperature power components, and integration of the developed components and devices into a demonstrable 200 C power system, such as inverter. An overview of the program and a description of the in-house high temperature facilities along with experimental data obtained on high temperature materials are presented.

  18. High Temperature Chemistry at NASA: Hot Topics

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.

    2014-01-01

    High Temperature issues in aircraft engines Hot section: Ni and Co based Superalloys Oxidation and Corrosion (Durability) at high temperatures. Thermal protection system (TPS) and RCC (Reinforced Carbon-Carbon) on the Space Shuttle Orbiter. High temperatures in other worlds: Planets close to their stars.

  19. M"ossbauer study of corrosion and abrasion products in oil transporting pipes

    NASA Astrophysics Data System (ADS)

    Gomez, Raul W.; Perez Mazariego, Jose Luis; Marquina, Vivianne; Marquina, Ma. Luisa; Ridaura, Rosalia; Martinez, Lorenzo

    2012-02-01

    It is known that one of the main technological problems in carbon steel oleoducts is the corrosion produced by different substances, such as water, carbon dioxide, sulfur, and microorganisms. In addition, if in such mixture there is sand, aggressive sludge can be form that abrasions material from the oleoduct. A room temperature M"ossbauer study of corroded material taken from different sites of oleoducts is presented. Most of the M"ossbauer spectra reveal the presence of nanoparticles, indicating that in these pipes the abrasion problem is severe. A preliminary identification of the oxidized samples suggests the presence of magnetite, and some Iron hydroxides. Further studies are in course in order to identify unambiguously the products present in the corroded materials.

  20. High-Temperature Shape Memory Alloys

    NASA Astrophysics Data System (ADS)

    Biffi, C. A.; Tuissi, A.

    2014-10-01

    In this paper, an experimental study of laser micro-processing on a Cu-Zr-based shape memory alloy (SMA), which is suitable for high-temperature (HT) applications, is discussed. A first evaluation of the interaction between a laser beam and Zr50Cu28Ni7Co15 HT SMA is highlighted. Single laser pulses at various levels of power and pulse duration were applied to evaluate their effect on the sample surfaces. Blind and through microholes were produced with sizes on the order of a few hundreds of microns; the results were characterized from the morphological viewpoint using a scanning electron microscope. The high beam quality allows the holes to be created with good circularity and little melted material around the hole periphery. An analysis of the chemical composition was performed using energy dispersive spectroscopy, revealing that compositional changes were limited, while important oxidation occurred on the hole surfaces. Additionally, laser micro-cutting tests were also proposed to evaluate the cut edge morphology and dimensions. The main result of this paper concerned the good behavior of the material upon interaction with the laser beam, which suggests that microfeatures can be successfully produced in this alloy.

  1. High temperature behavior of zirconium germanates

    SciTech Connect

    Utkin, A.V.; Baklanova, N.I.; Vasilyeva, I.G.

    2013-05-01

    The high temperature behavior of zirconium germanates ZrGeO₄ and Zr₃GeO₈ up to 2300 °C has been studied using the original photoemission thermal analysis technique with the comprehensive physicochemical study of solid and gaseous intermediate and final products. The two-stage process of incongruent sublimation of GeO₂ was established and the phase boundary of the homogeneity range for ZrGeO₄ and Zr₃GeO₈ were deduced from the thermal analysis, X-ray diffraction and Raman spectroscopy studies. A high tendency to sintering of the final ZrO₂ product is discussed. - Graphical abstract: The decomposition of zirconium germanates leads to the formation of gaseous GeO₂ and solid sintered ZrO₂ and occurs via two stages with the formation of intermediate ZrO₂-rich solid solution. Highlights: •Thermal behavior of ZrGeO₄ and Zr₃GeO₈ was studied using the original thermal analysis technique in wide temperature range. •The decomposition occurs via two stages with the formation of intermediate ZrO₂-rich solid solution. •The decomposition of zirconium germanates leads to the formation of gaseous GeO₂ and solid sintered ZrO₂. •The temperature of decomposition is strongly depended on the total gas pressure.

  2. Multifunctional, High-Temperature Nanocomposites

    NASA Technical Reports Server (NTRS)

    Connell, John W.; Smith, Joseph G.; Siochi, Emilie J.; Working, Dennis C.; Criss, Jim M.; Watson, Kent A.; Delozier, Donavon M.; Ghose, Sayata

    2007-01-01

    In experiments conducted as part of a continuing effort to incorporate multifunctionality into advanced composite materials, blends of multi-walled carbon nanotubes and a resin denoted gPETI-330 h (wherein gPETI h is an abbreviation for gphenylethynyl-terminated imide h) were prepared, characterized, and fabricated into moldings. PETI-330 was selected as the matrix resin in these experiments because of its low melt viscosity (<10 poise at a temperature of 280 C), excellent melt stability (lifetime >2 hours at 280 C), and high temperature performance (>1,000 hours at 288 C). The multi-walled carbon nanotubes (MWCNTs), obtained from the University of Kentucky, were selected because of their electrical and thermal conductivity and their small diameters. The purpose of these experiments was to determine the combination of thermal, electrical, and mechanical properties achievable while still maintaining melt processability. The PETI-330/MWCNT mixtures were prepared at concentrations ranging from 3 to 25 weight-percent of MWCNTs by dry mixing of the constituents in a ball mill using zirconia beads. The resulting powders were characterized for degree of mixing and thermal and rheological properties. The neat resin was found to have melt viscosity between 5 and 10 poise. At 280 C and a fixed strain rate, the viscosity was found to increase with time. At this temperature, the phenylethynyl groups do not readily react and so no significant curing of the resin occurred. For MWCNT-filled samples, melt viscosity was reasonably steady at 280 C and was greater in samples containing greater proportions of MWCNTs. The melt viscosity for 20 weightpercent of MWCNTs was found to be .28,000 poise, which is lower than the initial estimated allowable maximum value of 60,000 poise for injection molding. Hence, MWCNT loadings of as much as 20 percent were deemed to be suitable compositions for scale-up. High-resolution scanning electron microscopy (HRSEM) showed the MWCNTs to be well

  3. Use of d-3He proton spectroscopy as a diagnostic of shell rho r in capsule implosion experiments with approximately 0.2 NIF scale high temperature Hohlraums at Omega.

    PubMed

    Delamater, N D; Wilson, D C; Kyrala, G A; Seifter, A; Hoffman, N M; Dodd, E; Singleton, R; Glebov, V; Stoeckl, C; Li, C K; Petrasso, R; Frenje, J

    2008-10-01

    We present the calculations and preliminary results from experiments on the Omega laser facility using d-(3)He filled plastic capsule implosions in gold Hohlraums. These experiments aim to develop a technique to measure shell rho r and capsule unablated mass with proton spectroscopy and will be applied to future National Ignition Facility (NIF) experiments with ignition scale capsules. The Omega Hohlraums are 1900 microm length x 1200 microm diameter and have a 70% laser entrance hole. This is approximately a 0.2 NIF scale ignition Hohlraum and reaches temperatures of 265-275 eV similar to those during the peak of the NIF drive. These capsules can be used as a diagnostic of shell rho r, since the d-(3)He gas fill produces 14.7 MeV protons in the implosion, which escape through the shell and produce a proton spectrum that depends on the integrated rho r of the remaining shell mass. The neutron yield, proton yield, and spectra change with capsule shell thickness as the unablated mass or remaining capsule rho r changes. Proton stopping models are used to infer shell unablated mass and shell rho r from the proton spectra measured with different filter thicknesses. The experiment is well modeled with respect to Hohlraum energetics, neutron yields, and x-ray imploded core image size, but there are discrepancies between the observed and simulated proton spectra.

  4. High temperature silicon carbide impregnated insulating fabrics

    NASA Technical Reports Server (NTRS)

    Schomburg, C.; Dotts, R. L. (Inventor)

    1982-01-01

    High temperature insulating articles having improved performance characteristics are described. The articles comprise fabrics of closely woven refractory or heat resistant fibers having particles of silicon carbide dispersed at least partially through the fabric and bonded to the fibers with an emulsifiable polyethylene wax. Such articles exhibit significantly increased high temperature emittance characteristics and an improved retention of integrity and flexibility after prolonged exposure to high temperature.

  5. Deep Trek High Temperature Electronics Project

    SciTech Connect

    Bruce Ohme

    2007-07-31

    This report summarizes technical progress achieved during the cooperative research agreement between Honeywell and U.S. Department of Energy to develop high-temperature electronics. Objects of this development included Silicon-on-Insulator (SOI) wafer process development for high temperature, supporting design tools and libraries, and high temperature integrated circuit component development including FPGA, EEPROM, high-resolution A-to-D converter, and a precision amplifier.

  6. Dynamic, High-Temperature, Flexible Seal

    NASA Technical Reports Server (NTRS)

    Steinetz, Bruce M.; Sirocky, Paul J.

    1989-01-01

    New seal consists of multiple plies of braided ceramic sleeves filled with small ceramic balls. Innermost braided sleeve supported by high-temperature-wire-mesh sleeve that provides both springback and preload capabilities. Ceramic balls reduce effect of relatively high porosity of braided ceramic sleeves by acting as labyrinth flow path for gases and thereby greatly increasing pressure gradient seal can sustain. Dynamic, high-temperature, flexible seal employed in hypersonic engines, two-dimensional convergent/divergent and vectorized-thrust exhaust nozzles, reentry vehicle airframes, rocket-motor casings, high-temperature furnaces, and any application requiring non-asbestos high-temperature gaskets.

  7. Investigation of Radiation Affected High Temperature Superconductors - YBCO

    NASA Astrophysics Data System (ADS)

    Veterníková, J.; Chudý, M.; Slugeň, V.; Sojak, S.; Degmová, J.; Snopek, J.

    In this paper, high temperature superconductors are studied in terms of radiation stability, which is necessary for application in fusion reactors. Perspective superconducting materials based on YBCO (Perkovskite structure) were measured by positron annihilation lifetime spectroscopy. Measurements were performed for samples prior to and after fast neutron irradiation in TRIGA MARK II reactor in Vienna. The samples demonstrated accumulation of Cu-O di-vacancies due to the irradiation. Nevertheless, the structure showed regeneration during thermal treatment by defects recombination. Positron spectroscopy results were complemented with values of critical temperature, which also showed changes of superconducting properties after the irradiation and the annealing.

  8. Diamond anvil cell for spectroscopic investigation of materials at high temperature, high pressure and shear

    DOEpatents

    Westerfield, Curtis L.; Morris, John S.; Agnew, Stephen F.

    1997-01-01

    Diamond anvil cell for spectroscopic investigation of materials at high temperature, high pressure and shear. A cell is described which, in combination with Fourier transform IR spectroscopy, permits the spectroscopic investigation of boundary layers under conditions of high temperature, high pressure and shear.

  9. Diamond anvil cell for spectroscopic investigation of materials at high temperature, high pressure and shear

    DOEpatents

    Westerfield, C.L.; Morris, J.S.; Agnew, S.F.

    1997-01-14

    Diamond anvil cell is described for spectroscopic investigation of materials at high temperature, high pressure and shear. A cell is described which, in combination with Fourier transform IR spectroscopy, permits the spectroscopic investigation of boundary layers under conditions of high temperature, high pressure and shear. 4 figs.

  10. High temperature superconducting fault current limiter

    DOEpatents

    Hull, John R.

    1997-01-01

    A fault current limiter (10) for an electrical circuit (14). The fault current limiter (10) includes a high temperature superconductor (12) in the electrical circuit (14). The high temperature superconductor (12) is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter (10).

  11. High temperature superconducting fault current limiter

    DOEpatents

    Hull, J.R.

    1997-02-04

    A fault current limiter for an electrical circuit is disclosed. The fault current limiter includes a high temperature superconductor in the electrical circuit. The high temperature superconductor is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter. 15 figs.

  12. Silicon carbide, a high temperature semiconductor

    NASA Technical Reports Server (NTRS)

    Powell, J. A.

    1983-01-01

    Electronic applications are described that would benefit from the availability of high temperature semiconductor devices. Comparisons are made among potential materials for these devices and the problems of each are discussed. Recent progress in developing silicon carbide as a high temperature semiconductor is described.

  13. Effects of Palagonitic Dust Coatings on Visible, Near-IR, and Mossbauer Spectra of Rocks and Minerals: Implication for Mineralogical Remote Sensing of Mars

    NASA Technical Reports Server (NTRS)

    Morris, R.; Graff, T. G.; Shelfer, T. D.; Bell, J. F., III

    2001-01-01

    Visible, near-IR, and Mossbauer measurements on dust coated rocks and minerals show that a 300 5m thick layer is required to obscure the substrate for VNIR measurements and that a greater than 2000-micron-thick layer is required to obscure the substrate for Mossbauer measurements. Additional information is contained in the original extended abstract.

  14. Aeronautical applications of high-temperature superconductors

    NASA Technical Reports Server (NTRS)

    Turney, George E.; Luidens, Roger W.; Uherka, Kenneth; Hull, John

    1989-01-01

    The successful development of high-temperature superconductors (HTS) could have a major impact on future aeronautical propulsion and aeronautical flight vehicle systems. A preliminary examination of the potential application of HTS for aeronautics indicates that significant benefits may be realized through the development and implementation of these newly discovered materials. Applications of high-temperature superconductors (currently substantiated at 95 K) were envisioned for several classes of aeronautical systems, including subsonic and supersonic transports, hypersonic aircraft, V/STOL aircraft, rotorcraft, and solar, microwave and laser powered aircraft. Introduced and described are the particular applications and potential benefits of high-temperature superconductors as related to aeronautics and/or aeronautical systems.

  15. Symposium on high temperature and materials chemistry

    SciTech Connect

    Not Available

    1989-10-01

    This volume contains the written proceedings of the Symposium on High Temperature and Materials Chemistry held in Berkeley, California on October 24--25, 1989. The Symposium was sponsored by the Materials and Chemical Sciences Division of Lawrence Berkeley Laboratory and by the College of Chemistry of the University of California at Berkeley to discuss directions, trends, and accomplishments in the field of high temperature and materials chemistry. Its purpose was to provide a snapshot of high temperature and materials chemistry and, in so doing, to define status and directions.

  16. The high temperature superconductivity space experiment

    NASA Technical Reports Server (NTRS)

    Webb, Denis C.; Nisenoff, M.

    1991-01-01

    The history and the current status of the high temperature superconductivity space experiment (HTSSE) initiated in 1988 are briefly reviewed. The goal of the HTSSE program is to demonstrate the feasibility of incorporating high temperature superconductivity (HTS) technology into space systems. The anticipated payoffs include the development of high temperature superconductor devices for space systems; preparation and space qualification of a cryogenically cooled experimental package containing HTS devices and components; and acquisition of data for future space experiments using more complex HTS devices and subsystems. The principal HTSSE systems and devices are described.

  17. Dimensionality of high temperature superconductivity in oxides

    NASA Technical Reports Server (NTRS)

    Chu, C. W.

    1989-01-01

    Many models have been proposed to account for the high temperature superconductivity observed in oxide systems. Almost all of these models proposed are based on the uncoupled low dimensional carrier Cu-O layers of the oxides. Results of several experiments are presented and discussed. They suggest that the high temperature superconductivity observed cannot be strictly two- or one-dimensional, and that the environment between the Cu-O layers and the interlayer coupling play an important role in the occurrence of such high temperature superconductivity. A comment on the very short coherence length reported is also made.

  18. High temperature resistant cermet and ceramic compositions

    NASA Technical Reports Server (NTRS)

    Phillips, W. M. (Inventor)

    1978-01-01

    Cermet compositions having high temperature oxidation resistance, high hardness and high abrasion and wear resistance, and particularly adapted for production of high temperature resistant cermet insulator bodies are presented. The compositions are comprised of a sintered body of particles of a high temperature resistant metal or metal alloy, preferably molybdenum or tungsten particles, dispersed in and bonded to a solid solution formed of aluminum oxide and silicon nitride, and particularly a ternary solid solution formed of a mixture of aluminum oxide, silicon nitride and aluminum nitride. Also disclosed are novel ceramic compositions comprising a sintered solid solution of aluminum oxide, silicon nitride and aluminum nitride.

  19. A high-temperature wideband pressure transducer

    NASA Technical Reports Server (NTRS)

    Zuckerwar, A. J.

    1975-01-01

    Progress in the development of a pressure transducer for measurement of the pressure fluctuations in the high temperature environment of a jet exhaust is reported. A condenser microphone carrier system was adapted to meet the specifications. A theoretical analysis is presented which describes the operation of the condenser microphone in terms of geometry, materials, and other physical properties. The analysis was used as the basis for design of a prototype high temperature microphone. The feasibility of connecting the microphone to a converter over a high temperature cable operating as a half-wavelength transmission line was also examined.

  20. /sup 57/Fe Mossbauer spectroscopy of U/sub 6/Fe

    SciTech Connect

    Lemon, G.; Boolchand, P.; Stevens, M.; DeLong, L.E.; Huber, J.G.; Marcuso, M.

    1986-04-01

    Samples of U/sub 6/Fe were prepared by arc melting U and enriched /sup 57/Fe. The samples display superconducting transitions which are sensitive to long-term exposure to air. Room temperature spectra of U/sub 6/Fe typically display a majority site A (quadrupole splitting ..delta.. = 0.749(3) mm/s, isomer shift delta = 0.482(6) mm/s relative to Cu) and a minority site B (..delta.. = 0.55(3) mm/s, sigma = 0.12(3) mm/s) with the site intensity ratio (I/sub B//I/sub A/) typically 0.05 to 0.10. The I/sub B//I/sub A/ intensity ratio increases upon air exposure of the samples. We have studied Moessbauer spectra as a function of temperature T in the range 15/sup 0/K less than or equal to T less than or equal to 310/sup 0/K paying particular attention to the T-variation of the isomer-shift and recoil-free-fraction of the majority site A. Results indicate a consistent softening of lattice vibrations of U/sub 6/Fe at T approx. = 170/sup 0/K.

  1. The MER Mossbauer Spectrometers: 40 Months of Operation on the Martian Surface

    NASA Technical Reports Server (NTRS)

    Fleischer, Iris; Rodionov, D.; Schroeder, C.; Morris, R.; Yen, A.; Ming, D.; McCoy, T.; Mittlefehldt, D.; Gellert, R.; Cohen, B.; Schmidt, M.; Klingelhoefer, Goestar

    2007-01-01

    The primary MER objectives have been successfully completed. The total integration time of all MB measurements exceeds the duration of the primary 90-sols-mission for Spirit's MB spectrometer, and approaches this value for Opportunity's MB spectrometer. Both MB spectrometers continue to accumulate valuable scientific data after three years of operation (data is available for download [13]) The identification of aqueous minerals such as goethite in Gusev crater and jarosite at Meridiani Planum by the MER Mossbauer spectrometers is strong evidence for past water activity at the two landing sites.

  2. Effect of thermal history on Mossbauer signature and hyperfine interaction parameters of copper ferrite

    SciTech Connect

    Modi, K. B. Raval, P. Y.; Dulera, S. V.; Kathad, C. R.; Shah, S. J.; Trivedi, U. N.; Chandra, Usha

    2015-06-24

    Two specimens of copper ferrite, CuFe{sub 2}O{sub 4}, have been synthesized by double sintering ceramic technique with different thermal history i.e. slow cooled and quenched. X-ray diffractometry has confirmed single phase fcc spinel structure for slow cooled sample while tetragonal distortion is present in quenched sample. Mossbauer spectral analysis for slow-cooled copper ferrite reveals super position of two Zeeman split sextets along with paramagnetic singlet in the centre position corresponds to delafossite (CuFeO{sub 2}) phase that is completely absent in quenched sample. The hyperfine interaction parameters are highly influenced by heat treatment employed.

  3. Effect of thermal history on Mossbauer signature and hyperfine interaction parameters of copper ferrite

    NASA Astrophysics Data System (ADS)

    Modi, K. B.; Raval, P. Y.; Dulera, S. V.; Kathad, C. R.; Shah, S. J.; Trivedi, U. N.; Chandra, Usha

    2015-06-01

    Two specimens of copper ferrite, CuFe2O4, have been synthesized by double sintering ceramic technique with different thermal history i.e. slow cooled and quenched. X-ray diffractometry has confirmed single phase fcc spinel structure for slow cooled sample while tetragonal distortion is present in quenched sample. Mossbauer spectral analysis for slow-cooled copper ferrite reveals super position of two Zeeman split sextets along with paramagnetic singlet in the centre position corresponds to delafossite (CuFeO2) phase that is completely absent in quenched sample. The hyperfine interaction parameters are highly influenced by heat treatment employed.

  4. Measuring Moduli Of Elasticity At High Temperatures

    NASA Technical Reports Server (NTRS)

    Wolfenden, Alan

    1993-01-01

    Shorter, squatter specimens and higher frequencies used in ultrasonic measurement technique. Improved version of piezo-electric ultrasonic composite oscillator technique used to measure moduli of elasticity of solid materials at high temperatures.

  5. Silicon carbide, an emerging high temperature semiconductor

    NASA Technical Reports Server (NTRS)

    Matus, Lawrence G.; Powell, J. Anthony

    1991-01-01

    In recent years, the aerospace propulsion and space power communities have expressed a growing need for electronic devices that are capable of sustained high temperature operation. Applications for high temperature electronic devices include development instrumentation within engines, engine control, and condition monitoring systems, and power conditioning and control systems for space platforms and satellites. Other earth-based applications include deep-well drilling instrumentation, nuclear reactor instrumentation and control, and automotive sensors. To meet the needs of these applications, the High Temperature Electronics Program at the Lewis Research Center is developing silicon carbide (SiC) as a high temperature semiconductor material. Research is focussed on developing the crystal growth, characterization, and device fabrication technologies necessary to produce a family of silicon carbide electronic devices and integrated sensors. The progress made in developing silicon carbide is presented, and the challenges that lie ahead are discussed.

  6. High-temperature superconductivity: A conventional conundrum

    DOE PAGESBeta

    Božović, Ivan

    2016-01-07

    High-temperature superconductivity in ultrathin films of iron selenide deposited on strontium titanate has been attributed to various exotic mechanisms, and new experiments indicate that it may be conventional, with broader implications.

  7. The Conference on High Temperature Electronics

    NASA Technical Reports Server (NTRS)

    Hamilton, D. J.; Mccormick, J. B.; Kerwin, W. J.; Narud, J. A.

    1981-01-01

    The status of and directions for high temperature electronics research and development were evaluated. Major objectives were to (1) identify common user needs; (2) put into perspective the directions for future work; and (3) address the problem of bringing to practical fruition the results of these efforts. More than half of the presentations dealt with materials and devices, rather than circuits and systems. Conference session titles and an example of a paper presented in each session are (1) User requirements: High temperature electronics applications in space explorations; (2) Devices: Passive components for high temperature operation; (3) Circuits and systems: Process characteristics and design methods for a 300 degree QUAD or AMP; and (4) Packaging: Presently available energy supply for high temperature environment.

  8. Altering high temperature subterranean formation permeability

    SciTech Connect

    Moradi-Araghi, A.

    1991-02-19

    This patent describes a delayed acrylamide containing polymer crosslinker having stability in an aqueous solution at high temperatures. It comprises: a combination of an aldehyde and a salicylic acid derivative selected from salicylamide and acetysalicylic acid.

  9. Materials for high-temperature thermoelectric conversion

    NASA Technical Reports Server (NTRS)

    Feigelson, R. S.; Elwell, D.; Auld, B. A.

    1984-01-01

    The development of materials for high temperature thermoelectric energy conversion devices was investigated. The development of new criteria for the selection of materials which is based on understanding of the fundamental principles governing the behavior of high temperature thermoelectric materials is discussed. The synthesis and characterization of promising new materials and the growth of single crystals to eliminate possible problems associated with grain boundaries and other defects in polycrystalline materials are outlined.

  10. PLA recycling by hydrolysis at high temperature

    NASA Astrophysics Data System (ADS)

    Cristina, Annesini Maria; Rosaria, Augelletti; Sara, Frattari; Fausto, Gironi

    2016-05-01

    In this work the process of PLA hydrolysis at high temperature was studied, in order to evaluate the possibility of chemical recycling of this polymer bio-based. In particular, the possibility to obtain the monomer of lactic acid from PLA degradation was investigated. The results of some preliminary tests, performed in a laboratory batch reactor at high temperature, are presented: the experimental results show that the complete degradation of PLA can be obtained in relatively low reaction times.

  11. Recent developments in high temperature organic polymers

    NASA Technical Reports Server (NTRS)

    Hergenrother, P. M.

    1991-01-01

    Developments in high temperature organic polymers during the last 5 years with major emphasis on polyimides and poly(arylene ether)s are discussed. Specific polymers or series of polymers have been selected to demonstrate unique properties or the effect chemical structure has upon certain properties. This article is not intended to be a comprehensive review of high temperature polymer advancements during the last 5 years.

  12. High-temperature Solar Cell Development

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Merritt, Danielle; Raffaelle, Ryne P.; Scheiman, David

    2005-01-01

    The vast majority of space probes to date have relied upon photovoltaic power generation. If future missions designed to probe environments close to the sun (Figure 1) will be able to use such power generation, solar cells that can function at high temperatures, under high light intensity, and high radiation conditions must be developed. The significant problem is that solar cells lose performance at high temperatures.

  13. High temperature tensile testing of ceramic composites

    NASA Technical Reports Server (NTRS)

    Gyekenyesi, John Z.; Hemann, John H.

    1988-01-01

    The various components of a high temperature tensile testing system are evaluated. The objective is the high temperature tensile testing of SiC fiber reinforced reaction bonded Si3N4 specimens at test temperatures up to 1650 C (3000 F). Testing is to be conducted in inert gases and air. Gripping fixtures, specimen configurations, furnaces, optical strain measuring systems, and temperature measurement techniques are reviewed. Advantages and disadvantages of the various techniques are also noted.

  14. Investigations into High Temperature Components and Packaging

    SciTech Connect

    Marlino, L.D.; Seiber, L.E.; Scudiere, M.B.; M.S. Chinthavali, M.S.; McCluskey, F.P.

    2007-12-31

    The purpose of this report is to document the work that was performed at the Oak Ridge National Laboratory (ORNL) in support of the development of high temperature power electronics and components with monies remaining from the Semikron High Temperature Inverter Project managed by the National Energy Technology Laboratory (NETL). High temperature electronic components are needed to allow inverters to operate in more extreme operating conditions as required in advanced traction drive applications. The trend to try to eliminate secondary cooling loops and utilize the internal combustion (IC) cooling system, which operates with approximately 105 C water/ethylene glycol coolant at the output of the radiator, is necessary to further reduce vehicle costs and weight. The activity documented in this report includes development and testing of high temperature components, activities in support of high temperature testing, an assessment of several component packaging methods, and how elevated operating temperatures would impact their reliability. This report is organized with testing of new high temperature capacitors in Section 2 and testing of new 150 C junction temperature trench insulated gate bipolar transistor (IGBTs) in Section 3. Section 4 addresses some operational OPAL-GT information, which was necessary for developing module level tests. Section 5 summarizes calibration of equipment needed for the high temperature testing. Section 6 details some additional work that was funded on silicon carbide (SiC) device testing for high temperature use, and Section 7 is the complete text of a report funded from this effort summarizing packaging methods and their reliability issues for use in high temperature power electronics. Components were tested to evaluate the performance characteristics of the component at different operating temperatures. The temperature of the component is determined by the ambient temperature (i.e., temperature surrounding the device) plus the

  15. Nearly Perfect Fluidity in a High Temperature Superconductor

    DOE PAGESBeta

    Rameau, J. D.; Reber, T. J.; Yang, H. -B.; Akhanjee, S.; Gu, G. D.; Johnson, P. D.; Campbell, S.

    2014-10-13

    Perfect fluids are characterized as having the smallest ratio of shear viscosity to entropy density, η/s, consistent with quantum uncertainty and causality. So far, nearly perfect fluids have only been observed in the quark-gluon plasma and in unitary atomic Fermi gases, exotic systems that are amongst the hottest and coldest objects in the known universe, respectively. We use angle resolved photoemission spectroscopy to measure the temperature dependence of an electronic analog of η/s in an optimally doped cuprate high-temperature superconductor, finding it too is a nearly perfect fluid around, and above, its superconducting transition temperature Tc.

  16. Nearly Perfect Fluidity in a High Temperature Superconductor

    SciTech Connect

    Rameau, J. D.; Reber, T. J.; Yang, H. -B.; Akhanjee, S.; Gu, G. D.; Johnson, P. D.; Campbell, S.

    2014-10-13

    Perfect fluids are characterized as having the smallest ratio of shear viscosity to entropy density, η/s, consistent with quantum uncertainty and causality. So far, nearly perfect fluids have only been observed in the quark-gluon plasma and in unitary atomic Fermi gases, exotic systems that are amongst the hottest and coldest objects in the known universe, respectively. We use angle resolved photoemission spectroscopy to measure the temperature dependence of an electronic analog of η/s in an optimally doped cuprate high-temperature superconductor, finding it too is a nearly perfect fluid around, and above, its superconducting transition temperature Tc.

  17. Sandia_HighTemperatureComponentEvaluation_2015.

    SciTech Connect

    Cashion, Avery T.

    2015-03-01

    The objective of this project is to perform independent evaluation of high temperature components to determine their suitability for use in high temperature geothermal tools. Development of high temperature components has been increasing rapidly due to demand from the high temperature oil and gas exploration and aerospace industries. Many of these new components are at the late prototype or first production stage of development and could benefit from third party evaluation of functionality and lifetime at elevated temperatures. In addition to independent testing of new components, this project recognizes that there is a paucity of commercial-off-the-shelf COTS components rated for geothermal temperatures. As such, high-temperature circuit designers often must dedicate considerable time and resources to determine if a component exists that they may be able to knead performance out of to meet their requirements. This project aids tool developers by characterization of select COTS component performances beyond published temperature specifications. The process for selecting components includes public announcements of project intent (e.g., FedBizOps), direct discussions with candidate manufacturers,and coordination with other DOE funded programs.

  18. Nuclear fuels for very high temperature applications

    SciTech Connect

    Lundberg, L.B.; Hobbins, R.R.

    1992-01-01

    The success of the development of nuclear thermal propulsion devices and thermionic space nuclear power generation systems depends on the successful utilization of nuclear fuel materials at temperatures in the range 2000 to 3500 K. Problems associated with the utilization of uranium bearing fuel materials at these very high temperatures while maintaining them in the solid state for the required operating times are addressed. The critical issues addressed include evaporation, melting, reactor neutron spectrum, high temperature chemical stability, fabrication, fission induced swelling, fission product release, high temperature creep, thermal shock resistance, and fuel density, both mass and fissile atom. Candidate fuel materials for this temperature range are based on UO{sub 2} or uranium carbides. Evaporation suppression, such as a sealed cladding, is required for either fuel base. Nuclear performance data needed for design are sparse for all candidate fuel forms in this temperature range, especially at the higher temperatures.

  19. High temperature thrust chamber for spacecraft

    NASA Technical Reports Server (NTRS)

    Chazen, Melvin L. (Inventor); Mueller, Thomas J. (Inventor); Kruse, William D. (Inventor)

    1998-01-01

    A high temperature thrust chamber for spacecraft (20) is provided herein. The high temperature thrust chamber comprises a hollow body member (12) having an outer surface and an internal surface (16) defining the high temperature chamber (10). The body member (12) is made substantially of rhenium. An alloy (18) consisting of iridium and at least alloying metal selected of the group consisting of rhodium, platinum and palladium is deposited on at least a portion of the internal surface (16) of the body member (12). The iridium and the alloying metal are electrodeposited onto the body member (12). A HIP cycle is performed upon the body member (12) to cause the coating of iridium and the alloying metal to form the alloy (18) which protects the body member (12) from oxidation.

  20. High-temperature geothermal reservoir engineering

    SciTech Connect

    Schroeder, R.C.; Benson, S.; Goranson, C.

    1980-02-01

    A review of high-temperature geothermal reservoir engineering is presented. High-temperature downhole conditions encountered during field activities are reviewed with data from Cerro Prieto as the primary example. The types of measurements required for estimation of formation parameter values and how they depend on other geoscience data are reviewed. The analysis techniques that are currently used to evaluate field data are discussed and their limitations, applicability, and associated difficulties are described using data from Cerro Prieto as an example. Downhole tools that are needed for high-temperature measurements are discussed with a review of the current state of the art. The use of measured data in reservoir engineering simulation calculations is summarized, and different numerical models are reviewed. Data from Cerro Prieto are used as an example to show how reserves and reservoir depletion calculations can be used to aid the field developer in choosing operational field strategies.

  1. High Temperature Membrane & Advanced Cathode Catalyst Development

    SciTech Connect

    Protsailo, Lesia

    2006-04-20

    Current project consisted of three main phases and eighteen milestones. Short description of each phase is given below. Table 1 lists program milestones. Phase 1--High Temperature Membrane and Advanced Catalyst Development. New polymers and advanced cathode catalysts were synthesized. The membranes and the catalysts were characterized and compared against specifications that are based on DOE program requirements. The best-in-class membranes and catalysts were downselected for phase 2. Phase 2--Catalyst Coated Membrane (CCM) Fabrication and Testing. Laboratory scale catalyst coated membranes (CCMs) were fabricated and tested using the down-selected membranes and catalysts. The catalysts and high temperature membrane CCMs were tested and optimized. Phase 3--Multi-cell stack fabrication. Full-size CCMs with the down-selected and optimized high temperature membrane and catalyst were fabricated. The catalyst membrane assemblies were tested in full size cells and multi-cell stack.

  2. Nuclear fuels for very high temperature applications

    SciTech Connect

    Lundberg, L.B.; Hobbins, R.R.

    1992-08-01

    The success of the development of nuclear thermal propulsion devices and thermionic space nuclear power generation systems depends on the successful utilization of nuclear fuel materials at temperatures in the range 2000 to 3500 K. Problems associated with the utilization of uranium bearing fuel materials at these very high temperatures while maintaining them in the solid state for the required operating times are addressed. The critical issues addressed include evaporation, melting, reactor neutron spectrum, high temperature chemical stability, fabrication, fission induced swelling, fission product release, high temperature creep, thermal shock resistance, and fuel density, both mass and fissile atom. Candidate fuel materials for this temperature range are based on UO{sub 2} or uranium carbides. Evaporation suppression, such as a sealed cladding, is required for either fuel base. Nuclear performance data needed for design are sparse for all candidate fuel forms in this temperature range, especially at the higher temperatures.

  3. Structural characterization of high temperature composites

    NASA Technical Reports Server (NTRS)

    Mandell, J. F.; Grande, D. H.

    1991-01-01

    Glass, ceramic, and carbon matrix composite materials have emerged in recent years with potential properties and temperature resistance which make them attractive for high temperature applications such as gas turbine engines. At the outset of this study, only flexural tests were available to evaluate brittle matrix composites at temperatures in the 600 to 1000 C range. The results are described of an ongoing effort to develop appropriate tensile, compression, and shear test methods for high temperature use. A tensile test for unidirectional composites was developed and used to evaluate the properties and behavior of ceramic fiber reinforced glass and glass-ceramic matrix composites in air at temperatures up to 1000 C. The results indicate generally efficient fiber reinforcement and tolerance to matrix cracking similar to polymer matrix composites. Limiting properties in these materials may be an inherently very low transverse strain to failure, and high temperature embrittlement due to fiber/matrix interface oxidation.

  4. Copper Alloy For High-Temperature Uses

    NASA Technical Reports Server (NTRS)

    Dreshfield, Robert L.; Ellis, David L.; Michal, Gary

    1994-01-01

    Alloy of Cu/8Cr/4Nb (numbers indicate parts by atom percent) improved over older high-temperature copper-based alloys in that it offers enhanced high temperature strength, resistance to creep, and ductility while retaining most of thermal conductivity of pure copper; in addition, alloy does not become embrittled upon exposure to hydrogen at temperatures as high as 705 degrees C. Designed for use in presence of high heat fluxes and active cooling; for example, in heat exchangers in advanced aircraft and spacecraft engines, and other high-temperature applications in which there is need for such material. High conductivity and hardness of alloy exploited in welding electrodes and in high-voltage and high-current switches and other applications in which wear poses design problem.

  5. High Temperature, Wireless Seismometer Sensor for Venus

    NASA Technical Reports Server (NTRS)

    Ponchak, George E.; Scardelletti, Maximilian C.; Taylor, Brandt; Beard, Steve; Meredith, Roger D.; Beheim, Glenn M.; Hunter Gary W.; Kiefer, Walter S.

    2012-01-01

    Space agency mission plans state the need to measure the seismic activity on Venus. Because of the high temperature on Venus (462? C average surface temperature) and the difficulty in placing and wiring multiple sensors using robots, a high temperature, wireless sensor using a wide bandgap semiconductor is an attractive option. This paper presents the description and proof of concept measurements of a high temperature, wireless seismometer sensor for Venus. A variation in inductance of a coil caused by the movement of an aluminum probe held in the coil and attached to a balanced leaf-spring seismometer causes a variation of 700 Hz in the transmitted signal from the oscillator/sensor system at 426? C. This result indicates that the concept may be used on Venus.

  6. High temperature structural fibers: Status and needs

    NASA Technical Reports Server (NTRS)

    Dicarlo, James A.

    1991-01-01

    The key to high temperature structural composites is the selection and incorporation of continuous fiber reinforcement with optimum mechanical, physical, and chemical properties. Critical fiber property needs are high strength, high stiffness, and retention of these properties during composite fabrication and use. However, unlike polymeric composites where all three requirements are easily achieved with a variety of commercially available carbon-based fibers, structural fibers with sufficient stiffness and strength retention for high temperature metal, intermetallic, and ceramic composites are not available. The objective here is to discuss in a general manner the thermomechanical stability problem for current high performance fibers which are based on silicon and alumina compositions. This is accomplished by presenting relevant fiber property data with a brief discussion of potential underlying mechanisms. From this general overview, some possible materials engineering approaches are suggested which may lead to minimization and/or elimination of this critical stability problem for current high temperature fibers.

  7. Raman Spectroscopy.

    ERIC Educational Resources Information Center

    Gerrard, Donald L.

    1984-01-01

    Reviews literature on Raman spectroscopy from late 1981 to late 1983. Topic areas include: instrumentation and sampling; liquids and solutions; gases and matrix isolation; biological molecules; polymers; high-temperature and high-pressure studies; Raman microscopy; thin films and surfaces; resonance-enhanced and surface-enhanced spectroscopy; and…

  8. Development of high temperature strain gages

    NASA Technical Reports Server (NTRS)

    Lemcoe, M. M.

    1973-01-01

    High temperature electric resistance wire strain gages were developed and evaluated for use at temperatures exceeding 922 K (1200 F). A special high temperature strain gage alloy (Fe-25Cr-7.5A1), designated BCL-3, was used to fabricate the gages. Pertinent gage characteristics were determined at temperatures up to 1255 K (1800 F). The results of the evaluation were reported in graphical and tabular form. It was concluded that the gages will perform satisfactorily at temperatures to at least 1089 K (1500 F) for at least one hour.

  9. Micromechanics of high temperature deformation and failure

    NASA Technical Reports Server (NTRS)

    Nasser, S. N.; Weertman, J. R.

    1985-01-01

    The micromechanics of the constitutive behavior of elastoplastic materials at high temperatures was examined. The experimental work focused on the development of microscopic defects in superalloys (Waspaloy), especially the formation of voids at grain boundary carbides, and slip induced surface cracks within grains upon cyclic loading at high temperatures. The influence of these defects on the life expectancy of the material was examined. The theoretical work consists of two parts: (1) analytical description of the mechanisms that lead to defects observed experimentally; and (2) development of macroscopic elastoplastic nonlinear constitutive relations based on mechanical modeling.

  10. High temperature crystalline superconductors from crystallized glasses

    DOEpatents

    Shi, Donglu

    1992-01-01

    A method of preparing a high temperature superconductor from an amorphous phase. The method involves preparing a starting material of a composition of Bi.sub.2 Sr.sub.2 Ca.sub.3 Cu.sub.4 Ox or Bi.sub.2 Sr.sub.2 Ca.sub.4 Cu.sub.5 Ox, forming an amorphous phase of the composition and heat treating the amorphous phase for particular time and temperature ranges to achieve a single phase high temperature superconductor.

  11. High temperature solid state storage cell

    DOEpatents

    Rea, Jesse R.; Kallianidis, Milton; Kelsey, G. Stephen

    1983-01-01

    A completely solid state high temperature storage cell comprised of a solid rechargeable cathode such as TiS.sub.2, a solid electrolyte which remains solid at the high temperature operating conditions of the cell and which exhibits high ionic conductivity at such elevated temperatures such as an electrolyte comprised of lithium iodide, and a solid lithium or other alkali metal alloy anode (such as a lithium-silicon alloy) with 5-50% by weight of said anode being comprised of said solid electrolyte.

  12. Introduction to high-temperature superconductivity

    SciTech Connect

    Sheahen, T.P.

    1994-12-31

    The Electric Power Research Institute, as part of its program to develop high-temperature superconductivity applications for the power industry, has endevoured to educate utility engineers and executives on superconductivity. This book is a series of tutorials prepared by the Argonne National Laboratory. Part one is at an introductory level, asking and answering the question `What is superconductivity?` Part 2 is an exposition of the basic properties of the new materials - structure, phase equilibria, effects of doping, etc. with consideration of theoretical issues. Part 3 covers potential practical uses of high temperature superconductors.

  13. Enamel for high-temperature superalloys

    NASA Technical Reports Server (NTRS)

    Levin, H.; Lent, W. E.

    1977-01-01

    Desired optical and high temperature enamel properties are obtained with glasses prepared from the system Li2O-ZrO2-nSiO2. Molar compositions range from n=4 to n=1.3, to which are added minor amounts in varying combinations of alumina, alkali fluorides, boric oxide, alkali oxides, and akaline earth oxides.

  14. 10.3 High-temperature Instrumentation

    NASA Technical Reports Server (NTRS)

    Piazza, Anthony

    2008-01-01

    This viewgraph presentation describes high temperature instrumentation development from 1960-1970, 1980-1990 and 2000-present. The contents include: 1) Background; 2) Objective; 3) Application and Sensor; 4) Attachment Techniques; 5) Evaluation/Characterization Testing; and 6) Future testing.

  15. Electrical Properties Of Capacitors At High Temperatures

    NASA Technical Reports Server (NTRS)

    Baumann, E. D.; Myers, I. T.; Overton, E.; Hammoud, A. N.

    1994-01-01

    Brief report describes results of experiments in which capacitance and dielectric loss of glass, metallized-polytetrafluoroethylene, and solid-tantalum capacitor measured at temperatures from 20 degrees C to 200 degrees C. Conclusions drawn concerning suitability of capacitors for use at high temperatures; such as in nuclear powerplants, aircraft, equipment for extracting geothermal energy, switching power supplies, and automotive integrated engine electronics.

  16. Progress in advanced high temperature materials technology

    NASA Technical Reports Server (NTRS)

    Freche, J. C.; Ault, G. M.

    1976-01-01

    Significant progress has recently been made in many high temperature material categories pertinent to such applications by the industrial community. These include metal matrix composites, superalloys, directionally solidified eutectics, coatings, and ceramics. Each of these material categories is reviewed and the current state-of-the-art identified, including some assessment, when appropriate, of progress, problems, and future directions.

  17. High temperature pressure coupled ultrasonic waveguide

    DOEpatents

    Caines, Michael J.

    1983-01-01

    A pressure coupled ultrasonic waveguide is provided to which one end may be attached a transducer and at the other end a high temperature material for continuous ultrasonic testing of the material. The ultrasonic signal is coupled from the waveguide into the material through a thin, dry copper foil.

  18. Lightweight High-Temperature Thermal Insulation

    NASA Technical Reports Server (NTRS)

    Wagner, W. R.; Fasheh, J. I.

    1985-01-01

    Fine Ni/Cr fibers sintered into corrosion-resistant, fireproof batt. Possible applications include stoves, furnaces, safes, fire clothing, draperies in public buildings, wall firebreaks, airplane walls, and jetengine components. New insulation takes advantage of some of same properties of nickel/chromium alloy useful in heating elements in toasters, namely, corrosion and oxidation resistance even at high temperatures.

  19. Space applications of high temperature superconductivity technology

    NASA Technical Reports Server (NTRS)

    Connolly, D. J.; Aron, P. R.; Leonard, R. F.; Wintucky, E. G.

    1991-01-01

    A review is presented of the present status of high temperature superconductivity (HTS) technology and related areas of potential space application. Attention is given to areas of application that include microwave communications, cryogenic systems, remote sensing, and space propulsion and power. Consideration is given to HTS phase shifters, miniaturization of microwave filters, far-IR bolometers, and magnetic refrigeration using flux compression.

  20. High Temperature Filler for Tile Gaps

    NASA Technical Reports Server (NTRS)

    Holt, J. W.; Wang, D. S.

    1983-01-01

    Gaps between ceramic tiles filled with ceramic-coated fabric that withstands temperatures as high as 2,000 degrees F (1,300 degrees C). Reusable high-temperature gap filler is made of fabric coated with ceramic slurry and bonded in place with room-temperature-vulcanized adhesive. Procedure used in kilns and furnaces.

  1. Improved high-temperature silicide coatings

    NASA Technical Reports Server (NTRS)

    Klopp, W. D.; Stephens, J. R.; Stetson, A. R.; Wimber, R. T.

    1969-01-01

    Special technique for applying silicide coatings to refractory metal alloys improves their high-temperature protective capability. Refractory metal powders mixed with a baked-out organic binder and sintered in a vacuum produces a porous alloy layer on the surface. Exposing the layer to hot silicon converts it to a silicide.

  2. NDE standards for high temperature materials

    NASA Technical Reports Server (NTRS)

    Vary, Alex

    1991-01-01

    High temperature materials include monolithic ceramics for automotive gas turbine engines and also metallic/intermetallic and ceramic matrix composites for a range of aerospace applications. These are materials that can withstand extreme operating temperatures that will prevail in advanced high-efficiency gas turbine engines. High temperature engine components are very likely to consist of complex composite structures with three-dimensionality interwoven and various intermixed ceramic fibers. The thermomechanical properties of components made of these materials are actually created in-place during processing and fabrication stages. The complex nature of these new materials creates strong incentives for exact standards for unambiguous evaluations of defects and microstructural characteristics. NDE techniques and standards that will ultimately be applicable to production and quality control of high temperature materials and structures are still emerging. The needs range from flaw detection to below 100 micron levels in monolithic ceramics to global imaging of fiber architecture and matrix densification anomalies in composites. The needs are different depending on the processing stage, fabrication method, and nature of the finished product. The standards are discussed that must be developed in concert with advances in NDE technology, materials processing research, and fabrication development. High temperature materials and structures that fail to meet stringent specifications and standards are unlikely to compete successfully either technologically or in international markets.

  3. High temperature ceramic/metal joint structure

    DOEpatents

    Boyd, Gary L.

    1991-01-01

    A high temperature turbine engine includes a hybrid ceramic/metallic rotor member having ceramic/metal joint structure. The disclosed joint is able to endure higher temperatures than previously possible, and aids in controlling heat transfer in the rotor member.

  4. High-temperature corrosion in halogen environments

    SciTech Connect

    McNallan, M. )

    1994-09-01

    Halogen contaminants, particularly chlorine and fluorine, cause accelerated corrosion in such high-temperature systems as waste incinerators and waste heat recuperators on metallurgical furnaces. The mechanisms by which these phenomena occur are reviewed and discussed with the goal of identifying appropriate corrosion control strategies for materials that operate in these environments.

  5. High temperature oxidation resistant cermet compositions

    NASA Technical Reports Server (NTRS)

    Phillips, W. M. (Inventor)

    1976-01-01

    Cermet compositions are designed to provide high temperature resistant refractory coatings on stainless steel or molybdenum substrates. A ceramic mixture of chromium oxide and aluminum oxide form a coating of chromium oxide as an oxidation barrier around the metal particles, to provide oxidation resistance for the metal particles.

  6. Thermal disconnect for high-temperature batteries

    DOEpatents

    Jungst, Rudolph George; Armijo, James Rudolph; Frear, Darrel Richard

    2000-01-01

    A new type of high temperature thermal disconnect has been developed to protect electrical and mechanical equipment from damage caused by operation at extreme temperatures. These thermal disconnects allow continuous operation at temperatures ranging from 250.degree. C. to 450.degree. C., while rapidly terminating operation at temperatures 50.degree. C. to 150.degree. C. higher than the continuous operating temperature.

  7. High Temperature VARTM of Phenylethynyl Terminated Imides

    NASA Technical Reports Server (NTRS)

    Ghose, Sayata; Watson, Kent A.; Cano, Roberto J.; Britton, Sean M.; Jensen, Brian J.; Connell, John W.; Herring, Helen M.; Linberry, Quentin J.

    2009-01-01

    LaRC phenylethynyl terminated imide (PETI) resins were processed into composites using high temperature vacuum assisted resin transfer molding (VARTM). Although initial runs yielded composites with high void content, process modifications reduced voids to <3%. Photomicrographs were taken and void contents and T(sub g)s of the panels were determined.

  8. High Temperature Langasite SAW Oxygen Sensor

    SciTech Connect

    Zheng, Peng; Chin, Tao-Lun; Greve, David; Oppenheim, Irving; Malone, Vanessa; Cao, Limin

    2011-08-01

    High-temperature langasite SAW oxygen sensors using sputtered ZnO as a resistive gas-sensing layer were fabricated and tested. Sensitivity to oxygen gas was observed between 500°C to 700°C, with a sensitivity peak at about 625°C, consistent with the theoretical predictions of the acoustoelectric effect.

  9. High-Temperature Capacitor Polymer Films

    NASA Astrophysics Data System (ADS)

    Tan, Daniel; Zhang, Lili; Chen, Qin; Irwin, Patricia

    2014-12-01

    Film capacitor technology has been under development for over half a century to meet various applications such as direct-current link capacitors for transportation, converters/inverters for power electronics, controls for deep well drilling of oil and gas, direct energy weapons for military use, and high-frequency coupling circuitry. The biaxially oriented polypropylene film capacitor remains the state-of-the-art technology; however, it is not able to meet increasing demand for high-temperature (>125°C) applications. A number of dielectric materials capable of operating at high temperatures (>140°C) have attracted investigation, and their modifications are being pursued to achieve higher volumetric efficiency as well. This paper highlights the status of polymer dielectric film development and its feasibility for capacitor applications. High-temperature polymers such as polyetherimide (PEI), polyimide, and polyetheretherketone were the focus of our studies. PEI film was found to be the preferred choice for high-temperature film capacitor development due to its thermal stability, dielectric properties, and scalability.

  10. High temperature superconductor materials and applications

    NASA Technical Reports Server (NTRS)

    Doane, George B., III.; Banks, Curtis; Golben, John

    1990-01-01

    Research on processing methods leading to a significant enhancement in the critical current densities (Jc) and the critical temperature (Tc) of high temperature superconducting in thin bulk and thin film forms. The fabrication of important devices for NASA unique applications (sensors) is investigated.

  11. Mars Mineral Spectroscopy Web Site: A Resource for Remote Planetary Spectroscopy

    NASA Technical Reports Server (NTRS)

    Dyar, M. D.; Schaefer, M. W.; Griswold, J. L.; Hanify, K. M.; Rothstein, Y.

    2004-01-01

    A web site dedicated to Mars Mineral Spectroscopy has been established at http://www.mtholyoke.edu/go/mars. Its goal is to provide an easily accessible data set of Mossbauer spectra of minerals collected over a range of temperatures, to provide suitable analog spectra for data acquired on remote surfaces such as Mars. Complementing these data (eventually) will be both reflectance FTIR data, collected at Brown University's RELAB facility, and Raman spectra to be collected by Jill Pasteris at Washington University St. Louis. Through our Education link, we provide information for those wishing to learn about how Mossbauer and other types of spectroscopy work. Our emphasis is to study only well-characterized mineral samples that represent typical rock-forming occurrences such as might exist on Mars and other terrestrial bodies in our solar system.

  12. Properties of Martian Hematite at Meridiani Planum by Simultaneous Fitting of Mars Mossbauer Spectra

    NASA Technical Reports Server (NTRS)

    Agresti, D. G.; Fleischer, I.; Klingelhoefer, G.; Morris, R. V.

    2010-01-01

    Mossbauer spectrometers [1] on the two Mars Exploration Rovers (MERs) have been making measurements of surface rocks and soils since January 2004, recording spectra in 10-K-wide temperature bins ranging from 180 K to 290 K. Initial analyses focused on modeling individual spectra directly as acquired or, to increase statistical quality, as sums of single-rock or soil spectra over temperature or as sums over similar rock or soil type [2, 3]. Recently, we have begun to apply simultaneous fitting procedures [4] to Mars Mossbauer data [5-7]. During simultaneous fitting (simfitting), many spectra are modeled similarly and fit together to a single convergence criterion. A satisfactory simfit with parameter values consistent among all spectra is more likely than many single-spectrum fits of the same data because fitting parameters are shared among multiple spectra in the simfit. Consequently, the number of variable parameters, as well as the correlations among them, is greatly reduced. Here we focus on applications of simfitting to interpret the hematite signature in Moessbauer spectra acquired at Meridiani Planum, results of which were reported in [7]. The Spectra. We simfit two sets of spectra with large hematite content [7]: 1) 60 rock outcrop spectra from Eagle Crater; and 2) 46 spectra of spherule-rich lag deposits (Table 1). Spectra of 10 different targets acquired at several distinct temperatures are included in each simfit set. In the table, each Sol (martian day) represents a different target, NS is the number of spectra for a given sol, and NT is the number of spectra for a given temperature. The spectra are indexed to facilitate definition of parameter relations and constraints. An example spectrum is shown in Figure 1, together with a typical fitting model. Results. We have shown that simultaneous fitting is effective in analyzing a large set of related MER Mossbauer spectra. By using appropriate constraints, we derive target-specific quantities and the

  13. High Temperature Thermographic Phosphor Coatings Development

    NASA Technical Reports Server (NTRS)

    Goedeke, Shawn; Allison, S. W.; Beshears, D. L.; Bencic, T.; Cates, M. R.; Hollerman, W. A.; Guidry, R.

    2003-01-01

    For many years, phosphor thermometry has been used for non-contact temperature measurements. A large number of applications have been associated with high temperatures, especially for aerospace systems where blackbody radiation backgrounds are large and in challenging environments, such as vibration, rotation, flame, or noise. These environments restrict the use of more common thermocouples or infrared thermometric techniques. In particular, temperature measurements inside jet turbines, rocket engines, or similar devices are especially amenable to phosphor techniques. Often the fluorescent materials are used as powders, either suspended in binders and applied like paint or applied as high-temperature sprays. Thin coatings that are less than 50 m thick are used on the surfaces of interest. These coatings will quickly assume the same temperature as the surface to which they are applied. The temperature dependence of fluorescent materials is a function of the base matrix atoms and a small quantity of added activator or dopant ions. Often for high temperature applications, the selected materials are refractory and include rare earth ions. Phosphors like Y3Al5O12 (YAG) doped with Eu, Dy, or Tm, Y2O3 doped with Eu, or similar rare earth compounds, will survive high temperatures and can be configured to emit light that changes rapidly in lifetime and intensity. For example, researchers at Oak Ridge National Laboratory recently observed fluorescence from YAG:Dy and YAG:Tm at temperatures above 1400 C. One of the biggest challenges is to locate a binder material that can withstand tremendous variations in temperature in an adverse aerospace environment. This poster will provide an overview into our attempt to utilize phosphors for thermometry purposes. Emphasis will be placed on the use of selected binder materials that can withstand high temperatures. This research was completed for the National Aeronautics and Space Administration's Glenn Research Center in Cleveland

  14. High Temperature Materials Interim Data Qualification Report

    SciTech Connect

    Nancy Lybeck

    2010-08-01

    ABSTRACT Projects for the very high temperature reactor (VHTR) Technology Development Office provide data in support of Nuclear Regulatory Commission licensing of the VHTR. Fuel and materials to be used in the reactor are tested and characterized to quantify performance in high temperature and high fluence environments. The VHTR program has established the NGNP Data Management and Analysis System (NDMAS) to ensure that VHTR data are qualified for use, stored in a readily accessible electronic form, and analyzed to extract useful results. This document focuses on the first NDMAS objective. It describes the High Temperature Materials characterization data stream, the processing of these data within NDMAS, and reports the interim FY2010 qualification status of the data. Data qualification activities within NDMAS for specific types of data are determined by the data qualification category assigned by the data generator. The High Temperature Materials data are being collected under NQA-1 guidelines, and will be qualified data. For NQA-1 qualified data, the qualification activities include: (1) capture testing, to confirm that the data stored within NDMAS are identical to the raw data supplied, (2) accuracy testing to confirm that the data are an accurate representation of the system or object being measured, and (3) documenting that the data were collected under an NQA-1 or equivalent Quality Assurance program. Currently, data from two test series within the High Temperature Materials data stream have been entered into the NDMAS vault: 1. Tensile Tests for Sm (i.e., Allowable Stress) Confirmatory Testing – 1,403,994 records have been inserted into the NDMAS database. Capture testing is in process. 2. Creep-Fatigue Testing to Support Determination of Creep-Fatigue Interaction Diagram – 918,854 records have been processed and inserted into the NDMAS database. Capture testing is in process.

  15. High-temperature bulk acoustic wave sensors

    NASA Astrophysics Data System (ADS)

    Fritze, Holger

    2011-01-01

    Piezoelectric crystals like langasite (La3Ga5SiO14, LGS) and gallium orthophosphate (GaPO4) exhibit piezoelectrically excited bulk acoustic waves at temperatures of up to at least 1450 °C and 900 °C, respectively. Consequently, resonant sensors based on those materials enable new sensing approaches. Thereby, resonant high-temperature microbalances are of particular interest. They correlate very small mass changes during film deposition onto resonators or gas composition-dependent stoichiometry changes of thin films already deposited onto the resonators with the resonance frequency shift of such devices. Consequently, the objective of the work is to review the high-temperature properties, the operation limits and the measurement principles of such resonators. The electromechanical properties of high-temperature bulk acoustic wave resonators such as mechanical stiffness, piezoelectric and dielectric constant, effective viscosity and electrical conductivity are described using a one-dimensional physical model and determined accurately up to temperatures as close as possible to their ultimate limit. Insights from defect chemical models are correlated with the electromechanical properties of the resonators. Thereby, crucial properties for stable operation as a sensor under harsh conditions are identified to be the formation of oxygen vacancies and the bulk conductivity. Operation limits concerning temperature, oxygen partial pressure and water vapor pressure are given. Further, application-relevant aspects such as temperature coefficients, temperature compensation and mass sensitivity are evaluated. In addition, approximations are introduced which make the exact model handy for routine data evaluation. An equivalent electrical circuit for high-temperature resonator devices is derived based on the one-dimensional physical model. Low- and high-temperature approximations are introduced. Thereby, the structure of the equivalent circuit corresponds to the Butterworth

  16. High temperature furnace modeling and performance verifications

    NASA Technical Reports Server (NTRS)

    Smith, James E., Jr.

    1988-01-01

    Analytical, numerical and experimental studies were performed on two classes of high temperature materials processing furnaces. The research concentrates on a commercially available high temperature furnace using zirconia as the heating element and an arc furnace based on a ST International tube welder. The zirconia furnace was delivered and work is progressing on schedule. The work on the arc furnace was initially stalled due to the unavailability of the NASA prototype, which is actively being tested aboard the KC-135 experimental aircraft. A proposal was written and funded to purchase an additional arc welder to alleviate this problem. The ST International weld head and power supply were received and testing will begin in early November. The first 6 months of the grant are covered.

  17. High temperature aircraft research furnace facilities

    NASA Technical Reports Server (NTRS)

    Smith, James E., Jr.; Cashon, John L.

    1992-01-01

    Focus is on the design, fabrication, and development of the High Temperature Aircraft Research Furnace Facilities (HTARFF). The HTARFF was developed to process electrically conductive materials with high melting points in a low gravity environment. The basic principle of operation is to accurately translate a high temperature arc-plasma gas front as it orbits around a cylindrical sample, thereby making it possible to precisely traverse the entire surface of a sample. The furnace utilizes the gas-tungsten-arc-welding (GTAW) process, also commonly referred to as Tungsten-Inert-Gas (TIG). The HTARFF was developed to further research efforts in the areas of directional solidification, float-zone processing, welding in a low-gravity environment, and segregation effects in metals. The furnace is intended for use aboard the NASA-JSC Reduced Gravity Program KC-135A Aircraft.

  18. High Temperature Mechanisms for Venus Exploration

    NASA Astrophysics Data System (ADS)

    Ji, Jerri; Narine, Roop; Kumar, Nishant; Singh, Sase; Gorevan, Steven

    Future Venus missions, including New Frontiers Venus In-Situ Explorer and three Flagship Missions - Venus Geophysical Network, Venus Mobile Explorer and Venus Surface Sample Return all focus on searching for evidence of past climate change both on the surface and in the atmospheric composition as well as in the interior dynamics of the planet. In order to achieve these goals and objectives, many key technologies need to be developed for the Venus extreme environment. These key technologies include sample acquisition systems and other high-temperature mechanisms and mobility systems capable of extended operation when directly exposed to the Venus surface or lower atmosphere environment. Honeybee Robotics has developed two types of high temperature motors, the materials and components in both motors were selected based on the requirement to survive temperatures above a minimum of 460° C, at earth atmosphere. The prototype Switched Reluctance Motor (SRM) has been operated non-continuously for over 20 hours at Venus-like conditions (460° C temperature, mostly CO2 gas environment) and it remains functional. A drilling system, actuated by two SRMs was tested in Venus-like conditions, 460° C temperature and mostly CO2 gas environment, for more than 15 hours. The drill successfully completed three tests by drilling into chalk up to 6 inches deep in each test. A first generation Brushless DC (BLDC) Motor and high temperature resolver were also tested and the feasibility of the designs was demonstrated by the extended operation of both devices under Venus-like condition. Further development of the BLDC motor and resolver continues and these devices will, ultimately, be integrated into the development of a high temperature sample acquisition scoop and high temperature joint (awarded SBIR Phase II in October, 2007). Both the SR and BLDC motors will undergo extensive testing at Venus temperature and pressure (TRL6) and are expected to be mission ready before the next New

  19. Development of high strength, high temperature ceramics

    NASA Technical Reports Server (NTRS)

    Hall, W. B.

    1982-01-01

    Improvement in the high-pressure turbopumps, both fuel and oxidizer, in the Space Shuttle main engine were considered. The operation of these pumps is limited by temperature restrictions of the metallic components used in these pumps. Ceramic materials that retain strength at high temperatures and appear to be promising candidates for use as turbine blades and impellers are discussed. These high strength materials are sensitive to many related processing parameters such as impurities, sintering aids, reaction aids, particle size, processing temperature, and post thermal treatment. The specific objectives of the study were to: (1) identify and define the processing parameters that affect the properties of Si3N4 ceramic materials, (2) design and assembly equipment required for processing high strength ceramics, (3) design and assemble test apparatus for evaluating the high temperature properties of Si3N4, and (4) conduct a research program of manufacturing and evaluating Si3N4 materials as applicable to rocket engine applications.

  20. Silicon Carbide Nanotube Oxidation at High Temperatures

    NASA Technical Reports Server (NTRS)

    Ahlborg, Nadia; Zhu, Dongming

    2012-01-01

    Silicon Carbide Nanotubes (SiCNTs) have high mechanical strength and also have many potential functional applications. In this study, SiCNTs were investigated for use in strengthening high temperature silicate and oxide materials for high performance ceramic nanocomposites and environmental barrier coating bond coats. The high · temperature oxidation behavior of the nanotubes was of particular interest. The SiCNTs were synthesized by a direct reactive conversion process of multiwall carbon nanotubes and silicon at high temperature. Thermogravimetric analysis (TGA) was used to study the oxidation kinetics of SiCNTs at temperatures ranging from 800degC to1300degC. The specific oxidation mechanisms were also investigated.

  1. High temperature acclimation through PIF4 signaling.

    PubMed

    Proveniers, Marcel C G; van Zanten, Martijn

    2013-02-01

    Ambient temperature has direct consequences for plant functioning. Many plant species are able to adjust reproductive timing and development to optimize fitness to changes in ambient temperatures. Understanding the molecular networks of how plants cope with high temperatures is essential to counteract the effects of global warming and to secure future crop productivity. Several recent papers reported that Arabidopsis thaliana responses to changing light conditions and high temperature, and their underlying signaling mechanisms are highly similar and involve the basic helix-loop-helix (bHLH) transcription factor PHYTOCHROME INTERACTING FACTOR 4 (PIF4). In this opinion article we discuss the mechanisms of PIF4-mediated acclimation to increased ambient temperature with focus on timing of flowering and morphological acclimation.

  2. The metallurgy of high temperature alloys

    NASA Technical Reports Server (NTRS)

    Tien, J. K.; Purushothaman, S.

    1976-01-01

    Nickel-base, cobalt-base, and high nickel and chromium iron-base alloys are dissected, and their microstructural and chemical components are assessed with respect to the various functions expected of high temperature structural materials. These functions include the maintenance of mechanical integrity over the strain-rate spectrum from creep resistance through fatigue crack growth resistance, and such alloy stability expectations as microstructural coarsening resistance, phase instability resistance and oxidation and corrosion resistance. Special attention will be given to the perennial conflict and trade-off between strength, ductility and corrosion and oxidation resistance. The newest developments in the constitution of high temperature alloys will also be discussed, including aspects relating to materials conservation.

  3. High-temperature helium-loop facility

    SciTech Connect

    Tokarz, R.D.

    1981-09-01

    The high-temperature helium loop is a facility for materials testing in ultrapure helium gas at high temperatures. The closed loop system is capable of recirculating high-purity helium or helium with controlled impurities. The gas loop maximum operating conditions are as follows: 300 psi pressure, 500 lb/h flow rate, and 2100/sup 0/F temperature. The two test sections can accept samples up to 3.5 in. diameter and 5 ft long. The gas loop is fully instrumented to continuously monitor all parameters of loop operation as well as helium impurities. The loop is fully automated to operate continuously and requires only a daily servicing by a qualified operator to replenish recorder charts and helium makeup gas. Because of its versatility and high degree of parameter control, the helium loop is applicable to many types of materials research. This report describes the test apparatus, operating parameters, peripheral systems, and instrumentation system.

  4. Study of high temperature oxide superconductors

    NASA Astrophysics Data System (ADS)

    Wu, M. K.; Ashburn, J. R.; Higgins, C. A.; Carswell, W. E.; Loo, B. H.; Burns, D. H.; Ibrahim, A.; Rolin, T.; Peters, P. N.; Sisk, R. C.

    1988-01-01

    Experimental studies are reported whose results indicate that proper processing procedures are critical to the formation of high-temperature copper oxide superconductors. Superconducting 123 films can be fabricated using the green 211 phase as a substrate. The transition temperature and transition width characteristics of these films are better than those obtained when other oxide compounds are used as substrates. A compact or single-crystal 211 phase will be desirable as a substrate for high-quality thin films. A new high T(c) copper oxide compound with nonrare earth elements was prepared using high-temperature processing. A YBa2Cu3O7-Ag composite with improved electrical conductivity was also prepared.

  5. Hole-doped cuprate high temperature superconductors

    NASA Astrophysics Data System (ADS)

    Chu, C. W.; Deng, L. Z.; Lv, B.

    2015-07-01

    Hole-doped cuprate high temperature superconductors have ushered in the modern era of high temperature superconductivity (HTS) and have continued to be at center stage in the field. Extensive studies have been made, many compounds discovered, voluminous data compiled, numerous models proposed, many review articles written, and various prototype devices made and tested with better performance than their nonsuperconducting counterparts. The field is indeed vast. We have therefore decided to focus on the major cuprate materials systems that have laid the foundation of HTS science and technology and present several simple scaling laws that show the systematic and universal simplicity amid the complexity of these material systems, while referring readers interested in the HTS physics and devices to the review articles. Developments in the field are mostly presented in chronological order, sometimes with anecdotes, in an attempt to share some of the moments of excitement and despair in the history of HTS with readers, especially the younger ones.

  6. Magnetic suspension using high temperature superconducting cores

    NASA Technical Reports Server (NTRS)

    Scurlock, R. G.

    1992-01-01

    The development of YBCO high temperature superconductors, in wire and tape forms, is rapidly approaching the point where the bulk transport current density j vs magnetic field H characteristics with liquid nitrogen cooling will enable its use in model cores. On the other hand, BSCCO high temperature superconductor in wire form has poor j-H characteristics at 77 K today, although with liquid helium or hydrogen cooling, it appears to be superior to NbTi superconductor. Since liquid nitrogen cooling is approx. 100 times cheaper than liquid helium cooling, the use of YBCO is very attractive for use in magnetic suspension. The design is discussed of a model core to accommodate lift and drag loads up to 6000 and 3000 N respectively. A comparison is made between the design performance of a liquid helium cooled NbTi (or BSCCO) superconducting core and a liquid nitrogen cooled YBCO superconducting core.

  7. A high temperature superconductivity communications flight experiment

    NASA Technical Reports Server (NTRS)

    Ngo, P.; Krishen, K.; Arndt, D.; Raffoul, G.; Karasack, V.; Bhasin, K.; Leonard, R.

    1992-01-01

    The proposed high temperature superconductivity (HTSC) millimeter-wave communications flight experiment from the payload bay of the Space Shuttle Orbiter to the Advanced Communications Technology Satellite (ACTS) in geosynchronous orbit is described. The experiment will use a Ka-band HTSC phased array antenna and front-end electronics to receive a downlink communications signal from the ACTS. The discussion covers the system configuration, a description of the ground equipment, the spacecraft receiver, link performance, thermal loading, and the superconducting antenna array.

  8. Intermetallic-Based High-Temperature Materials

    SciTech Connect

    Sikka, V.K.

    1999-04-25

    The intermetallic-based alloys for high-temperature applications are introduced. General characteristics of intermetallics are followed by identification of nickel and iron aluminides as the most practical alloys for commercial applications. An overview of the alloy compositions, melting processes, and mechanical properties for nickel and iron aluminizes are presented. The current applications and commercial producers of nickel and iron aluminizes are given. A brief description of the future prospects of intermetallic-based alloys is also given.

  9. Establishment of Harrop, High-Temperature Viscometer

    SciTech Connect

    Schumacher, R.F.

    1999-11-05

    This report explains how the Harrop, High-Temperature Viscometer was installed, calibrated, and operated. This report includes assembly and alignment of the furnace, viscometer, and spindle, and explains the operation of the Brookfield Viscometer, the Harrop furnace, and the UDC furnace controller. Calibration data and the development of the spindle constant from NIST standard reference glasses is presented. A simple operational procedure is included.

  10. Corrosion Resistant Coatings for High Temperature Applications

    SciTech Connect

    Besman, T.M.; Cooley, K.M.; Haynes, J.A.; Lee, W.Y.; Vaubert, V.M.

    1998-12-01

    Efforts to increase efficiency of energy conversion devices have required their operation at ever higher temperatures. This will force the substitution of higher-temperature structural ceramics for lower temperature materials, largely metals. Yet, many of these ceramics will require protection from high temperature corrosion caused by combustion gases, atmospheric contaminants, or the operating medium. This paper discusses examples of the initial development of such coatings and materials for potential application in combustion, aluminum smelting, and other harsh environments.

  11. High temperature, flexible, fiber-preform seal

    NASA Technical Reports Server (NTRS)

    Steinetz, Bruce M. (Inventor); Strocky, Paul J. (Inventor)

    1992-01-01

    A seal is mounted in a rectangular groove in a movable structural panel. The seal comprises a fiber preform constructed of multiple layers of fiber having a uniaxial core. Helical fibers are wound over the core. The fibers are of materials capable of withstanding high temperatures and are both left-hand and right-hand wound. An outer layer wrapped over said helical fibers prevents abrasion damage.

  12. Thermal fuse for high-temperature batteries

    DOEpatents

    Jungst, Rudolph G.; Armijo, James R.; Frear, Darrel R.

    2000-01-01

    A thermal fuse, preferably for a high-temperature battery, comprising leads and a body therebetween having a melting point between approximately 400.degree. C. and 500.degree. C. The body is preferably an alloy of Ag--Mg, Ag--Sb, Al--Ge, Au--In, Bi--Te, Cd--Sb, Cu--Mg, In--Sb, Mg--Pb, Pb--Pd, Sb--Zn, Sn--Te, or Mg--Al.

  13. Passivation Of High-Temperature Superconductors

    NASA Technical Reports Server (NTRS)

    Vasquez, Richard P.

    1991-01-01

    Surfaces of high-temperature superconductors passivated with native iodides, sulfides, or sulfates formed by chemical treatments after superconductors grown. Passivating compounds nearly insoluble in and unreactive with water and protect underlying superconductors from effects of moisture. Layers of cuprous iodide and of barium sulfate grown. Other candidate passivating surface films: iodides and sulfides of bismuth, strontium, and thallium. Other proposed techniques for formation of passivating layers include deposition and gas-phase reaction.

  14. High Temperature Decomposition of Hydrogen Peroxide

    NASA Technical Reports Server (NTRS)

    Parrish, Clyde F. (Inventor)

    2004-01-01

    Nitric oxide (NO) is oxidized into nitrogen dioxide (NO2) by the high temperature decomposition of a hydrogen peroxide solution to produce the oxidative free radicals, hydroxyl and hydropemxyl. The hydrogen peroxide solution is impinged upon a heated surface in a stream of nitric oxide where it decomposes to produce the oxidative free radicals. Because the decomposition of the hydrogen peroxide solution occurs within the stream of the nitric oxide, rapid gas-phase oxidation of nitric oxide into nitrogen dioxide occurs.

  15. High temperature decomposition of hydrogen peroxide

    NASA Technical Reports Server (NTRS)

    Parrish, Clyde F. (Inventor)

    2005-01-01

    Nitric oxide (NO) is oxidized into nitrogen dioxide (NO2) by the high temperature decomposition of a hydrogen peroxide solution to produce the oxidative free radicals, hydroxyl and hydroperoxyl. The hydrogen peroxide solution is impinged upon a heated surface in a stream of nitric oxide where it decomposes to produce the oxidative free radicals. Because the decomposition of the hydrogen peroxide solution occurs within the stream of the nitric oxide, rapid gas-phase oxidation of nitric oxide into nitrogen dioxide occurs.

  16. High temperature superconductors for computer interconnect applications

    SciTech Connect

    Nilsson, B.J.L.

    1994-12-31

    High temperature superconductors, because of their extremely low loss at high frequencies and their high current handling capability, have the potential for use in computer interconnect boards. They offer the potential advantages of high interconnect density, reduced interconnect delays, and higher data rate. Because silicon CMOS circuits dramatically improve in performance at low temperatures, cooled computers may become attractive in the future to capture both the improved interconnect and circuit benefits.

  17. Caldron For High-Temperature Alloys

    NASA Technical Reports Server (NTRS)

    Geringer, Henry J.

    1989-01-01

    Induction-heated caldron melts high-temperature alloys. Prevents sort of contamination of melts occurring during arc melting in ceramic crucibles. Liquefies 200 grams of solid metal components of alloy like niobium aluminum and makes alloy homogeneous in less than 3 minutes. Plugged sleeve constitutes main body of caldron. Coolant flows through sleeve to prevent it from melting. Mandrel-wound induction coils adjusted to tune source of power. Also serves as mold for casting alloys into such shapes as bars.

  18. High Temperature Strain Gage Calibration Fixture

    NASA Technical Reports Server (NTRS)

    Vranas, T. (Inventor)

    1976-01-01

    An apparatus and method are described for calibrating high temperature strain gases which serve for both dead weight and constant deflection measurements. A cantilever support arm allows the test unit to slide into a furnace while one end is subjected to bending strain either by hanging weights upon it or by deflecting it with a push rod. The dual nature of the fixture permits both tests to be run without change of the test specimen or removal from the furnace.

  19. Bimodular high temperature planar oxygen gas sensor.

    PubMed

    Sun, Xiangcheng; Liu, Yixin; Gao, Haiyong; Gao, Pu-Xian; Lei, Yu

    2014-01-01

    A bimodular planar O2 sensor was fabricated using NiO nanoparticles (NPs) thin film coated yttria-stabilized zirconia (YSZ) substrate. The thin film was prepared by radio frequency (r.f.) magnetron sputtering of NiO on YSZ substrate, followed by high temperature sintering. The surface morphology of NiO NPs film was characterized by atomic force microscope (AFM) and scanning electron microscope (SEM). X-ray diffraction (XRD) patterns of NiO NPs thin film before and after high temperature O2 sensing demonstrated that the sensing material possesses a good chemical and structure stability. The oxygen detection experiments were performed at 500, 600, and 800°C using the as-prepared bimodular O2 sensor under both potentiometric and resistance modules. For the potentiometric module, a linear relationship between electromotive force (EMF) output of the sensor and the logarithm of O2 concentration was observed at each operating temperature, following the Nernst law. For the resistance module, the logarithm of electrical conductivity was proportional to the logarithm of oxygen concentration at each operating temperature, in good agreement with literature report. In addition, this bimodular sensor shows sensitive, reproducible and reversible response to oxygen under both sensing modules. Integration of two sensing modules into one sensor could greatly enrich the information output and would open a new venue in the development of high temperature gas sensors. PMID:25191652

  20. High temperature, high power piezoelectric composite transducers.

    PubMed

    Lee, Hyeong Jae; Zhang, Shujun; Bar-Cohen, Yoseph; Sherrit, Stewart

    2014-08-08

    Piezoelectric composites are a class of functional materials consisting of piezoelectric active materials and non-piezoelectric passive polymers, mechanically attached together to form different connectivities. These composites have several advantages compared to conventional piezoelectric ceramics and polymers, including improved electromechanical properties, mechanical flexibility and the ability to tailor properties by using several different connectivity patterns. These advantages have led to the improvement of overall transducer performance, such as transducer sensitivity and bandwidth, resulting in rapid implementation of piezoelectric composites in medical imaging ultrasounds and other acoustic transducers. Recently, new piezoelectric composite transducers have been developed with optimized composite components that have improved thermal stability and mechanical quality factors, making them promising candidates for high temperature, high power transducer applications, such as therapeutic ultrasound, high power ultrasonic wirebonding, high temperature non-destructive testing, and downhole energy harvesting. This paper will present recent developments of piezoelectric composite technology for high temperature and high power applications. The concerns and limitations of using piezoelectric composites will also be discussed, and the expected future research directions will be outlined.

  1. Bimodular high temperature planar oxygen gas sensor

    PubMed Central

    Sun, Xiangcheng; Liu, Yixin; Gao, Haiyong; Gao, Pu-Xian; Lei, Yu

    2014-01-01

    A bimodular planar O2 sensor was fabricated using NiO nanoparticles (NPs) thin film coated yttria-stabilized zirconia (YSZ) substrate. The thin film was prepared by radio frequency (r.f.) magnetron sputtering of NiO on YSZ substrate, followed by high temperature sintering. The surface morphology of NiO NPs film was characterized by atomic force microscope (AFM) and scanning electron microscope (SEM). X-ray diffraction (XRD) patterns of NiO NPs thin film before and after high temperature O2 sensing demonstrated that the sensing material possesses a good chemical and structure stability. The oxygen detection experiments were performed at 500, 600, and 800°C using the as-prepared bimodular O2 sensor under both potentiometric and resistance modules. For the potentiometric module, a linear relationship between electromotive force (EMF) output of the sensor and the logarithm of O2 concentration was observed at each operating temperature, following the Nernst law. For the resistance module, the logarithm of electrical conductivity was proportional to the logarithm of oxygen concentration at each operating temperature, in good agreement with literature report. In addition, this bimodular sensor shows sensitive, reproducible and reversible response to oxygen under both sensing modules. Integration of two sensing modules into one sensor could greatly enrich the information output and would open a new venue in the development of high temperature gas sensors. PMID:25191652

  2. High Temperature, High Power Piezoelectric Composite Transducers

    PubMed Central

    Lee, Hyeong Jae; Zhang, Shujun; Bar-Cohen, Yoseph; Sherrit, StewarT.

    2014-01-01

    Piezoelectric composites are a class of functional materials consisting of piezoelectric active materials and non-piezoelectric passive polymers, mechanically attached together to form different connectivities. These composites have several advantages compared to conventional piezoelectric ceramics and polymers, including improved electromechanical properties, mechanical flexibility and the ability to tailor properties by using several different connectivity patterns. These advantages have led to the improvement of overall transducer performance, such as transducer sensitivity and bandwidth, resulting in rapid implementation of piezoelectric composites in medical imaging ultrasounds and other acoustic transducers. Recently, new piezoelectric composite transducers have been developed with optimized composite components that have improved thermal stability and mechanical quality factors, making them promising candidates for high temperature, high power transducer applications, such as therapeutic ultrasound, high power ultrasonic wirebonding, high temperature non-destructive testing, and downhole energy harvesting. This paper will present recent developments of piezoelectric composite technology for high temperature and high power applications. The concerns and limitations of using piezoelectric composites will also be discussed, and the expected future research directions will be outlined. PMID:25111242

  3. Fast vortex core switching at high temperatures

    NASA Astrophysics Data System (ADS)

    Lebecki, Kristof M.; Legut, Dominik

    2016-08-01

    Fast ferromagnetic vortex core switching is investigated employing micromagnetic simulations. Short pulse (in the range of a few hundreds of picoseconds) of an in-plane oscillating magnetic field is applied to a thin disk (diameter 200 nm and thickness 20 nm) with material parameters resembling permalloy. Fundamental frequency of this excitation field is close to the resonance with the material spin waves. Thermal effects are introduced by replacing the Landau-Lifshitz-Gilbert equation by the Landau-Lifshitz-Bloch equation. Temperature from 300 K to 850 K is considered, just below the Curie temperature TC = 870 K. Calculations are done within the OOMMF simulation framework. We find that: (i) Period of the field necessary to switch the vortex increases approximately from 141 ps at 300 K to 572 ps for the high-temperature limit. (ii) Amplitude of the field necessary to switch the vortex core decreases roughly from 60 mT to 15 mT - even at high temperatures this amplitude is nonzero, contrary to the case of quasi-static switching. (iii) Time span between the excitation and switching (switching time) seems not to depend on the temperature. (iv) Duration of the switching itself (movement of the Bloch point in the sample) increases from a few picoseconds at low temperatures to tens of picoseconds at high temperatures.

  4. High Temperature Calibration Furnace System user's guide

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The High Temperature Calibration Furnace System (HTCFS) was developed by Summitec Corporation. It is a high precision instrument providing a constant temperature which can be used to calibrate high temperature thermocouples. Incorporating the many recent technological advances from the fields of optical fiber thermometry, material science, computer systems interfacing, and process control, the engineers at Summitec Corporation have been able to create a system that can reach a steady operating temperature of 1700 C. The precision for the system requires the measurement of temperature to be within 1 C in two hours and within 2 C in 24 hours. As documented, the experimental result shows that this system has been able to stay within .5 C in 5 hours. No other systems commercially available have been able to achieve such high temperature precision. This manual provides an overview of the system design, instructions for instrument setup, and operation procedures. Also included are a vendor list and the source codes for the custom-designed software.

  5. High-Temperature Behavior of Cellulose I

    SciTech Connect

    Matthews, James F.; Bergenstråhle, Malin; Beckham, Gregg T.; Himmel, Michael E.; Nimlos, Mark R.; Brady, John W.; Crowley, Michael F.

    2011-03-17

    We use molecular simulation to elucidate the structural behavior of small hydrated cellulose Iβ microfibrils heated to 227 °C (500 K) with two carbohydrate force fields. In contrast to the characteristic two-dimensional hydrogen-bonded layer sheets present in the cellulose Iβ crystal structure, we show that at high temperature a three-dimensional hydrogen bond network forms, made possible by hydroxymethyl groups changing conformation from trans–gauche (TG) to gauche–gauche (GG) in every second layer corresponding to “center” chains in cellulose Iβ and from TG to gauche–trans (GT) in the “origin” layer. The presence of a regular three-dimensional hydrogen bond network between neighboring sheets eliminates the possibility of twist, whereas two-dimensional hydrogen bonding allows for microfibril twist to occur. Structural features of this high-temperature phase as determined by molecular simulation may explain several experimental observations for which no detailed structural basis has been offered. This includes an explanation for the observed temperature and crystal size dependence for the extent of hydrogen/deuterium exchange, and diffraction patterns of cellulose at high temperature.

  6. Lightweight high-temperature fuel metering valves

    NASA Astrophysics Data System (ADS)

    Bennett, Joe

    AlliedSignal Fluid systems has provided fuel metering valve hardware to three aircraft engine manufacturers for evaluation. Two of the progams were Integrated High Performance Turbine Engine Technology (IHPTET) related. The third program was an IR&D effort. Bench tests and evaluation of all three valve designs have been completed, and one of the designs has actually been used for engine test. Engine testing of the other two valve designs is planned for the future. These three designs are similar, but each is intended to be usused in different system configurations, and each valve design offers unique features. The design approaches used for the three valve designs incorporate several new and innovative technologies, including high-temperature brushless dc motor actuators, low-pressure loss metering element design, fiber optic rotarty output position sensor, no-moving-parts oscillating jet flow meter, high-temperature RS (rapid solidification) aluminum alloy, high-temperature elastomeric seals, high-pressure shutoff capabilities, and closed loop electronic fuel flow metering.

  7. High temperature, high power piezoelectric composite transducers.

    PubMed

    Lee, Hyeong Jae; Zhang, Shujun; Bar-Cohen, Yoseph; Sherrit, Stewart

    2014-01-01

    Piezoelectric composites are a class of functional materials consisting of piezoelectric active materials and non-piezoelectric passive polymers, mechanically attached together to form different connectivities. These composites have several advantages compared to conventional piezoelectric ceramics and polymers, including improved electromechanical properties, mechanical flexibility and the ability to tailor properties by using several different connectivity patterns. These advantages have led to the improvement of overall transducer performance, such as transducer sensitivity and bandwidth, resulting in rapid implementation of piezoelectric composites in medical imaging ultrasounds and other acoustic transducers. Recently, new piezoelectric composite transducers have been developed with optimized composite components that have improved thermal stability and mechanical quality factors, making them promising candidates for high temperature, high power transducer applications, such as therapeutic ultrasound, high power ultrasonic wirebonding, high temperature non-destructive testing, and downhole energy harvesting. This paper will present recent developments of piezoelectric composite technology for high temperature and high power applications. The concerns and limitations of using piezoelectric composites will also be discussed, and the expected future research directions will be outlined. PMID:25111242

  8. High temperature erosion of nickel alloys

    SciTech Connect

    Zhou, J.

    1995-12-31

    High temperature erosion behavior was studied on three commercial nickel alloys, Inconel 718, Inconel 601 and Inconel X-750, using a vertical sand-blast type of erosion test rig. Effect of temperature on erosion was investigated by varying test temperature in six steps from ambient up to 800 C. Other erosion variables investigated included impingement angle, changed from 10{degree} to 90{degree}, and impingement velocity, covered a range of 40 to 90 m/s. Extensive studies on erosion surface morphological features were done on eroded or eroded-corroded specimen surfaces using scanning electron microscopy. Thermogravimetric analysis and scratch test revealed corrosion rate, characteristics of oxide scale formed at high temperature, and some effects of corrosion on erosion. It was found that variation of erosion rate with temperature was directly related to temperature-dependent mechanical property changes of the materials. The mechanisms of the high-temperature erosion were analyzed based on test results. It was observed that erosion was dominant in temperature range up to 800 C, while corrosion played increased roles in upper portion of the temperature range tested.

  9. Plasma synthesis of high temperature ceramic films

    SciTech Connect

    Brown, I.G.; Monteiro, O.R.

    1998-11-01

    Thin films of alumina, chromia, mullite, yttria and zirconia have been synthesized using a plasma-based method called metal plasma immersion ion implantation and deposition (Mepiiid)--a highly versatile plasma deposition technique with ion energy control. Monolithic films (a single ceramic component) and multilayer films (individual layers of different ceramic materials) were formed. The films were characterized for their composition and structure in a number of different ways, and the high temperature performance of the films was explored, particularly for their ability to maintain their integrity and adhesion when subjected to repetitive high temperature thermal cycling up 1100 C. We found that the films retain their adhesion and quality without any apparent degradation with time, even after a large number of cycles; (the tests were extended out to a total of 40 cycles each of 24 hours duration). After repetitive high temperature thermal cycling, the film-substrate adhesion was greater than {approx}70 Mpa, the instrumental limit of measurement, and the interface toughness was approximately 0.8 MPa m{sup 1/2}.

  10. Nickel alloys combat high-temperature corrosion

    SciTech Connect

    Agarwal, D.C.; Herda, W.R.; Brill, U.

    1995-10-01

    During the last few decades, a better understanding of alloying effects, advances in melting technology, and the development of controlled thermomechanical processing have led to new and improved high-temperature alloys. Most such alloys have sufficient amounts of chromium (with or without additions of aluminum or silicon) to form chromium oxide, alumina, and/or silica protective oxide scales, which provide resistance to environmental degradation. However, oxides cannot protect against failure by creep, mechanical or thermal fatigue, thermal shock, or embrittlement. In the real world, failure is typically caused by a combination of two or more attack modes, which synergistically accelerate degradation. To counter these attacks, two new nickel-base alloys have been developed, in which high-temperature corrosion resistance has been optimized by the careful addition of elements such as chromium, aluminum, silicon, and rare earths. They provide economical and reliable solutions to attack by oxygen, sulfur, halogens, carbon compounds, and nitrogen in a range of high-temperature applications. For example, Alloy 602CA is utilized in heat treating equipment, catalytic automotive parts, and chemical processing apparatus. Alloy 45TM has been successfully used in coal gasification equipment, incinerators, refineries, and process machinery involving severe sulfidizing conditions.

  11. High temperature dynamic engine seal technology development

    NASA Technical Reports Server (NTRS)

    Steinetz, Bruce M.; Dellacorte, Christopher; Machinchick, Michael; Mutharasan, Rajakkannu; Du, Guang-Wu; Ko, Frank; Sirocky, Paul J.; Miller, Jeffrey H.

    1992-01-01

    Combined cycle ramjet/scramjet engines being designed for advanced hypersonic vehicles, including the National Aerospace Plane (NASP), require innovative high temperature dynamic seals to seal the sliding interfaces of the articulated engine panels. New seals are required that will operate hot (1200 to 2000 F), seal pressures ranging from 0 to 100 psi, remain flexible to accommodate significant sidewall distortions, and resist abrasion over the engine's operational life. This report reviews the recent high temperature durability screening assessments of a new braided rope seal concept, braided of emerging high temperature materials, that shows promise of meeting many of the seal demands of hypersonic engines. The paper presents durability data for: (1) the fundamental seal building blocks, a range of candidate ceramic fiber tows; and for (2) braided rope seal subelements scrubbed under engine simulated sliding, temperature, and preload conditions. Seal material/architecture attributes and limitations are identified through the investigations performed. The paper summarizes the current seal technology development status and presents areas in which future work will be performed.

  12. Containerless measurements on liquids at high temperatures

    NASA Technical Reports Server (NTRS)

    Weber, Richard

    1993-01-01

    The application of containerless techniques for measurements of the thermophysical properties of high temperature liquids is reviewed. Recent results obtained in the materials research laboratories at Intersonics are also presented. Work to measure high temperature liquid properties is motivated by both the need for reliable property data for modeling of industrial processes involving molten materials and generation of data form basic modeling of materials behavior. The motivation for this work and examples of variations in thermophysical property values from the literature are presented. The variations may be attributed to changes in the specimen properties caused by chemical changes in the specimen and/or to measurement errors. The two methods used to achieve containerless conditions were aeroacoustic levitation and electromagnetic levitation. Their qualities are presented. The accompanying slides show the layout of levitation equipment and present examples of levitated metallic and ceramic specimens. Containerless techniques provide a high degree of control over specimen chemistry, nucleation and allow precise control of liquid composition to be achieved. Effects of minor additions can thus be measured in a systematic way. Operation in reduced gravity enables enhanced control of liquid motion which can allow measurement of liquid transport properties. Examples of nucleation control, the thermodynamics of oxide contamination removal, and control of the chromium content of liquid aluminum oxide by high temperature containerless processes are presented. The feasibility of measuring temperature, emissivity, liquidus temperature, enthalpy, surface tension, density, viscosity, and thermal diffusivity are discussed in the final section of the paper.

  13. High Temperature Fluoride Salt Test Loop

    SciTech Connect

    Aaron, Adam M.; Cunningham, Richard Burns; Fugate, David L.; Holcomb, David Eugene; Kisner, Roger A.; Peretz, Fred J.; Robb, Kevin R.; Wilson, Dane F.; Yoder, Jr, Graydon L.

    2015-12-01

    Effective high-temperature thermal energy exchange and delivery at temperatures over 600°C has the potential of significant impact by reducing both the capital and operating cost of energy conversion and transport systems. It is one of the key technologies necessary for efficient hydrogen production and could potentially enhance efficiencies of high-temperature solar systems. Today, there are no standard commercially available high-performance heat transfer fluids above 600°C. High pressures associated with water and gaseous coolants (such as helium) at elevated temperatures impose limiting design conditions for the materials in most energy systems. Liquid salts offer high-temperature capabilities at low vapor pressures, good heat transport properties, and reasonable costs and are therefore leading candidate fluids for next-generation energy production. Liquid-fluoride-salt-cooled, graphite-moderated reactors, referred to as Fluoride Salt Reactors (FHRs), are specifically designed to exploit the excellent heat transfer properties of liquid fluoride salts while maximizing their thermal efficiency and minimizing cost. The FHR s outstanding heat transfer properties, combined with its fully passive safety, make this reactor the most technologically desirable nuclear power reactor class for next-generation energy production. Multiple FHR designs are presently being considered. These range from the Pebble Bed Advanced High Temperature Reactor (PB-AHTR) [1] design originally developed by UC-Berkeley to the Small Advanced High-Temperature Reactor (SmAHTR) and the large scale FHR both being developed at ORNL [2]. The value of high-temperature, molten-salt-cooled reactors is also recognized internationally, and Czechoslovakia, France, India, and China all have salt-cooled reactor development under way. The liquid salt experiment presently being developed uses the PB-AHTR as its focus. One core design of the PB-AHTR features multiple 20 cm diameter, 3.2 m long fuel channels

  14. High temperature superconductors applications in telecommunications

    NASA Technical Reports Server (NTRS)

    Kumar, A. Anil; Li, Jiang; Zhang, Ming Fang

    1995-01-01

    The purpose of this paper is twofold: (1) to discuss high temperature superconductors with specific reference to their employment in telecommunications applications; and (2) to discuss a few of the limitations of the normally employed two-fluid model. While the debate on the actual usage of high temperature superconductors in the design of electronic and telecommunications devices - obvious advantages versus practical difficulties - needs to be settled in the near future, it is of great interest to investigate the parameters and the assumptions that will be employed in such designs. This paper deals with the issue of providing the microwave design engineer with performance data for such superconducting waveguides. The values of conductivity and surface resistance, which are the primary determining factors of a waveguide performance, are computed based on the two-fluid model. A comparison between two models - a theoretical one in terms of microscopic parameters (termed Model A) and an experimental fit in terms of macroscopic parameters (termed Model B) - shows the limitations and the resulting ambiguities of the two-fluid model at high frequencies and at temperatures close to the transition temperature. The validity of the two-fluid model is then discussed. Our preliminary results show that the electrical transport description in the normal and superconducting phases as they are formulated in the two-fluid model needs to be modified to incorporate the new and special features of high temperature superconductors. Parameters describing the waveguide performance - conductivity, surface resistance and attenuation constant - will be computed. Potential applications in communications networks and large scale integrated circuits will be discussed. Some of the ongoing work will be reported. In particular, a brief proposal is made to investigate of the effects of electromagnetic interference and the concomitant notion of electromagnetic compatibility (EMI/EMC) of high T

  15. High temperature superconductors applications in telecommunications

    SciTech Connect

    Kumar, A.A.; Li, J.; Zhang, M.F.

    1994-12-31

    The purpose of this paper is twofold: to discuss high temperature superconductors with specific reference to their employment in telecommunications applications; and to discuss a few of the limitations of the normally employed two-fluid model. While the debate on the actual usage of high temperature superconductors in the design of electronic and telecommunications devices-obvious advantages versus practical difficulties-needs to be settled in the near future, it is of great interest to investigate the parameters and the assumptions that will be employed in such designs. This paper deals with the issue of providing the microwave design engineer with performance data for such superconducting waveguides. The values of conductivity and surface resistance, which are the primary determining factors of a waveguide performance, are computed based on the two-fluid model. A comparison between two models-a theoretical one in terms of microscopic parameters (termed Model A) and an experimental fit in terms of macroscopic parameters (termed Model B)-shows the limitations and the resulting ambiguities of the two-fluid model at high frequencies and at temperatures close to the transition temperature. The validity of the two-fluid model is then discussed. Our preliminary results show that the electrical transport description in the normal and superconducting phases as they are formulated in the two-fluid model needs to be modified to incorporate the new and special features of high temperature superconductors. Parameters describing the waveguide performance-conductivity, surface resistance and attenuation constant-will be computed. Potential applications in communications networks and large scale integrated circuits will be discussed. Some of the ongoing work will be reported. In particular, a brief proposal is made to investigate of the effects of electromagnetic interference and the concomitant notion of electromagnetic compatibility (EMI/EMC) of high T{sub c} superconductors.

  16. High temperature barrier coatings for refractory metals

    NASA Technical Reports Server (NTRS)

    Malone, G. A.; Walech, T.

    1995-01-01

    Improvements in high temperature oxidation resistant metal coating technology will allow NASA and commercial entities to develop competitive civil space transport and communication systems. The success of investigations completed in this program will have a positive impact on broadening the technology base for high temperature materials. The work reported herein describes processes and procedures for successfully depositing coherent oxidation barrier coatings on refractory metals to prevent degradation under very severe operating environments. Application of the new technology developed is now being utilized in numerous Phase 3 applications through several prominent aerospace firms. Major achievements have included: (1) development of means to deposit thick platinum and rhodium coatings with lower stress and fewer microcracks than could be previously achieved; (2) development of processes to deposit thick adherent coatings of platinum group metals on refractory substrates that remain bonded through high temperature excursions and without need for intermediate coatings (bonding processes unique to specific refractory metals and alloys have been defined; (3) demonstration that useful alloys of refractory and platinum coatings can be made through thermal diffusion means; (4) demonstration that selected barrier coatings on refractory substrates can withstand severe oxidizing environments in the range of 1260 deg and 1760 deg C for long time periods essential to the life requirements of the hardware; and (5) successful application of the processes and procedures to prototype hardware. The results of these studies have been instrumental in improved thermal oxidation barrier coatings for the NASP propulsion system. Other Phase 3 applications currently being exploited include small uncooled thrusters for spacecraft and microsatellite maneuvering systems.

  17. Does Lafayette = Nakhla? Not necessarily so, based on 4.2K Mossbauer spectra of all of the SNC meteorites

    NASA Technical Reports Server (NTRS)

    Burns, Roger G.

    1991-01-01

    In previous Mossbauer spectral studies of many of the Shergotite Nakhlite Chassignite (SNC) meteorites, attention was drawn to the close similarities of spectrum profiles between Lafayette and Nakhla, which were once suggested to be identical meteorites. These observations led to the acquisition of Governador Valadares and another specimen of Nakhla, as well as Zagami and Shergotty, for Mossbauer spectral measurements at 4.2K. Results reported here demonstrate that there are subtle differences between the three nakhlites (Nakhla, Lafayette, and Governador Valadares), as there are for three of the shergottites (Shergotty, Zagami, EETA 79001/lithologies A and B) and olivine-dominated Chassigny and ALHA 77005, indicating that all eight of the SNC meteorites discovered to data fell independently to Earth.

  18. High temperature regenerable hydrogen sulfide removal agents

    DOEpatents

    Copeland, Robert J.

    1993-01-01

    A system for high temperature desulfurization of coal-derived gases using regenerable sorbents. One sorbent is stannic oxide (tin oxide, SnO.sub.2), the other sorbent is a metal oxide or mixed metal oxide such as zinc ferrite (ZnFe.sub.2 O.sub.4). Certain otherwise undesirable by-products, including hydrogen sulfide (H.sub.2 S) and sulfur dioxide (SO.sub.2) are reused by the system, and elemental sulfur is produced in the regeneration reaction. A system for refabricating the sorbent pellets is also described.

  19. Modeling forces in high-temperature superconductors

    SciTech Connect

    Turner, L. R.; Foster, M. W.

    1997-11-18

    We have developed a simple model that uses computed shielding currents to determine the forces acting on a high-temperature superconductor (HTS). The model has been applied to measurements of the force between HTS and permanent magnets (PM). Results show the expected hysteretic variation of force as the HTS moves first toward and then away from a permanent magnet, including the reversal of the sign of the force. Optimization of the shielding currents is carried out through a simulated annealing algorithm in a C++ program that repeatedly calls a commercial electromagnetic software code. Agreement with measured forces is encouraging.

  20. Search for new high temperature thermoelectric materials

    NASA Technical Reports Server (NTRS)

    Caillat, Thierry; Borshchevsky, Alex; Fleurial, Jean-Pierre

    1992-01-01

    Although important efforts are actually devoted to improve Si-Ge materials, their thermoelectric energy conversion efficiency remains relatively low and the nondimensional ZT value does not exceed 1. Higher values can be obtained by investigating new materials. A search for new high temperature thermoelectric materials identified a certain number of compounds between transition metals and bismuth, antimony and germanium as potential candidates. Results of the preliminary synthesis of samples by a variety of techniques (Bridgman, mechanical alloying) are presented as well as some electrical measurements. Some compounds showed interesting properties and need to be investigated in more details.

  1. Operator manual: High temperature heat pump

    NASA Astrophysics Data System (ADS)

    Dyer, D. F.; Maples, G.; Burch, T. E.; Chancellor, P. D.

    1980-03-01

    Experimental data were obtained from operating a high temperature heat pump system. The use of methanol as a working fluid necessitated careful monitoring of refrigerant temperatures and pressures with chemical analysis performed on the working fluid during scheduled down time. Materials sent to vendors and quotes received concerning equipment (compressor, evaporator, condensor, air heater, dryer, two accumulator tanks, and three expansion valves) are discussed. The detailed design and pricing estimates are included. Additional information on layout and construction; start-up; testing; shut down; scheduled maintenance and inspection; safety precautions; control system; and trouble shooting is presented.

  2. Aerospace applications of high temperature superconductivity

    NASA Technical Reports Server (NTRS)

    Heinen, V. O.; Connolly, D. J.

    1991-01-01

    Space application of high temperature superconducting (HTS) materials may occur before most terrestrial applications because of the passive cooling possibilities in space and because of the economic feasibility of introducing an expensive new technology which has a significant system benefit in space. NASA Lewis Research Center has an ongoing program to develop space technology capitalizing on the potential benefit of HTS materials. The applications being pursued include space communications, power and propulsion systems, and magnetic bearings. In addition, NASA Lewis is pursuing materials research to improve the performance of HTS materials for space applications.

  3. Precipitation Hardenable High Temperature Shape Memory Alloy

    NASA Technical Reports Server (NTRS)

    Noebe, Ronald Dean (Inventor); Draper, Susan L. (Inventor); Nathal, Michael V. (Inventor); Crombie, Edwin A. (Inventor)

    2010-01-01

    A composition of the invention is a high temperature shape memory alloy having high work output, and is made from (Ni+Pt+Y),Ti(100-x) wherein x is present in a total amount of 49-55 atomic % Pt is present in a total amount of 10-30 atomic %, Y is one or more of Au, Pd. and Cu and is present in a total amount of 0 to 10 atomic %. The alloy has a matrix phase wherein the total concentration of Ni, Pt, and the one or more of Pd. Au, and Cu is greater than 50 atomic %.

  4. Structural relationships in high temperature superconductors

    SciTech Connect

    Schuller, I.K.; Segre, C.U.; Hinks, D.G.; Jorgensen, J.D.; Soderholm, L.; Beno, M.; Zhang, K.

    1987-09-01

    The recent discovery of two types of metallic copper oxide compounds which are superconducting to above 90/sup 0/K has renewed interest in the search for new high temperature superconducting materials. It is significant that both classes of compounds, La/sub 2-x/Sr/sub x/CuO/sub 4-y/ and YBa/sub 2/Cu/sub 3/O/sub 7-delta/ are intimately related to the extensively studied perovskite family. Both compounds contain highly oxidized, covalently bonded Cu-O sublattices, however, they differ in geometry. In this paper we discuss the relationship of these features to the superconducting properties. 30 refs., 6 figs.

  5. Coal transformation under high-temperature catagenesis

    SciTech Connect

    Melenevsky, V.N.; Sokol, E.V.; Fomin, A.N.

    2006-07-01

    In this paper we consider products of natural pyrolysis of lignite, which resulted from the high-temperature spontaneous combustion of spoil heaps of the Chelyabinsk coal basin. These products were studied by pyrolysis, element and petrographic analyses, chromatomass spectrometry, and X-ray diffraction method. We have established that under reducing conditions, the degree of pyrogenic coal transformation and the composition of pyrolysis products vary greatly, from graphite-like phases to bitumens, and depend on the temperature and degree of the system openness.

  6. Nickel oxide, ceramic insulated, high temperature coating

    SciTech Connect

    Aprigliano, L.F.

    1987-01-27

    This patent describes a corrosion, oxidation, and heat resistant layered coating for a substrate material in a high temperature, corrosive environment, consisting of: a base layer selected from the group consisting of Aluminide and MCrAlY, wherein M is a metal selected from the group consisting of nickel, cobalt, and a combination thereof; a ceramic layer, impermeable to the metallic elements of the substrate material and the MCrAlY layer, and bonded to the substrate material by the MCrAlY layer; and, a nickel oxide layer, applied to the ceramic layer.

  7. High temperature aqueous stress corrosion testing device

    DOEpatents

    Bornstein, A.N.; Indig, M.E.

    1975-12-01

    A description is given of a device for stressing tensile samples contained within a high temperature, high pressure aqueous environment, thereby permitting determination of stress corrosion susceptibility of materials in a simple way. The stressing device couples an external piston to an internal tensile sample via a pull rod, with stresses being applied to the sample by pressurizing the piston. The device contains a fitting/seal arrangement including Teflon and weld seals which allow sealing of the internal system pressure and the external piston pressure. The fitting/seal arrangement allows free movement of the pull rod and the piston.

  8. 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.

  9. High Temperature Materials Laboratory third annual report

    SciTech Connect

    Tennery, V.J.; Foust, F.M.

    1990-12-01

    The High Temperature Materials Laboratory has completed its third year of operation as a designated DOE User Facility at the Oak Ridge National Laboratory. Growth of the user program is evidenced by the number of outside institutions who have executed user agreements since the facility began operation in 1987. A total of 88 nonproprietary agreements (40 university and 48 industry) and 20 proprietary agreements (1 university, 19 industry) are now in effect. Sixty-eight nonproprietary research proposals (39 from university, 28 from industry, and 1 other government facility) and 8 proprietary proposals were considered during this reporting period. Research projects active in FY 1990 are summarized.

  10. High temperature decomposition of hydrogen peroxide

    NASA Technical Reports Server (NTRS)

    Parrish, Clyde F. (Inventor)

    2004-01-01

    Nitric oxide (NO) is oxidized into nitrogen dioxide (NO.sub.2) by the high temperature decomposition of a hydrogen peroxide solution to produce the oxidative free radicals, hydroxyl and hydroperoxyl. The hydrogen peroxide solution is impinged upon a heated surface in a stream of nitric oxide where it decomposes to produce the oxidative free radicals. Because the decomposition of the hydrogen peroxide solution occurs within the stream of the nitric oxide, rapid gas-phase oxidation of nitric oxide into nitrogen dioxide occurs.

  11. High temperature decomposition of hydrogen peroxide

    NASA Technical Reports Server (NTRS)

    Parrish, Clyde F. (Inventor)

    2011-01-01

    Nitric oxide (NO) is oxidized into nitrogen dioxide (NO.sub.2) by the high temperature decomposition of a hydrogen peroxide solution to produce the oxidative free radicals, hydroxyl and hydroperoxyl. The hydrogen peroxide solution is impinged upon a heated surface in a stream of nitric oxide where it decomposes to produce the oxidative free radicals. Because the decomposition of the hydrogen peroxide solution occurs within the stream of the nitric oxide, rapid gas-phase oxidation of nitric oxide into nitrogen dioxide occurs.

  12. Fiber specklegram sensors sensitivities at high temperatures

    NASA Astrophysics Data System (ADS)

    Rodriguez-Cobo, L.; Lomer, M.; Lopez-Higuera, J. M.

    2015-09-01

    In this work, the sensitivity of Fiber Specklegram Sensors to high temperatures (up to 800ºC) have been studied. Two multimode silica fibers have been introduced into a tubular furnace while a HeNe laser source was launched into a fiber edge, projecting speckle patterns to a commercial webcam. A computer generated different heating and cooling sweeps while the specklegram evolution was recorded. The achieved results exhibit a remarkably linearity in FSS's sensitivity for temperatures under 800ºC, following the thermal expansion of fused silica.

  13. NEW APPROACHES: High temperature superconductors take off

    NASA Astrophysics Data System (ADS)

    Gough, Colin

    1998-01-01

    This article describes the progress made towards real engineering applications of high temperature superconductors (HTS) in the ten years following the Nobel Prize winning discovery by Bednorz and Müller in August 1986. Examples include HTS wires and tapes for more efficient and powerful electric motors and for increasing the electrical power into the heart of modern cities, HTS permanent magnets for levitation, microwave filters for cellular telephone networks, SQUIDs (superconducting quantum interference devices) to monitor foetal heart and brain signals, and a new generation of superfast logic devices based on the flux quantum.

  14. High temperature surface protection. [10 gas turbines

    NASA Technical Reports Server (NTRS)

    Levine, S. R.

    1978-01-01

    Alloys of the MCrAlX type are the basis for high temperature surface protection systems in gas turbines. M can be one or more of Ni, Co, or Fe and X denotes a reactive metal added to enhance oxide scale adherence. The selection and formation as well as the oxidation, hot corrosion and thermal fatigue performance of MCrAlX coatings are discussed. Coatings covered range from simple aluminides formed by pack cementation to the more advanced physical vapor deposition overlay coatings and developmental plasma spray deposited thermal barrier coatings.

  15. High temperature photoelectron emission and surface photovoltage in semiconducting diamond

    SciTech Connect

    Williams, G. T.; Cooil, S. P.; Roberts, O. R.; Evans, S.; Langstaff, D. P.; Evans, D. A.

    2014-08-11

    A non-equilibrium photovoltage is generated in semiconducting diamond at above-ambient temperatures during x-ray and UV illumination that is sensitive to surface conductivity. The H-termination of a moderately doped p-type diamond (111) surface sustains a surface photovoltage up to 700 K, while the clean (2 × 1) reconstructed surface is not as severely affected. The flat-band C 1s binding energy is determined from 300 K measurement to be 283.87 eV. The true value for the H-terminated surface, determined from high temperature measurement, is (285.2 ± 0.1) eV, corresponding to a valence band maximum lying 1.6 eV below the Fermi level. This is similar to that of the reconstructed (2 × 1) surface, although this surface shows a wider spread of binding energy between 285.2 and 285.4 eV. Photovoltage quantification and correction are enabled by real-time photoelectron spectroscopy applied during annealing cycles between 300 K and 1200 K. A model is presented that accounts for the measured surface photovoltage in terms of a temperature-dependent resistance. A large, high-temperature photovoltage that is sensitive to surface conductivity and photon flux suggests a new way to use moderately B-doped diamond in voltage-based sensing devices.

  16. High-temperature oxidation behavior of aluminized AISI 4130 steel

    NASA Astrophysics Data System (ADS)

    Badaruddin, Mohammad; Wang, Chaur Jeng; Wardono, Herry; Tarkono, Asmi, Dwi

    2016-02-01

    AISI 4130 steel was dipped into a molten aluminum bath at 700°C for 16 s to produce an aluminide coating on the steel substrate. The coating, which consisted of an Al-rich layer and an FeAl3 and Fe2Al5 intermetallic layer, strongly adhered to the steel substrate. High-temperature oxidation of the bare steel and aluminized steel was performed by thermogravimetry at 850°C for 49 h in static air. The oxidation products were characterized by scanning electron microscopy and energy-dispersive spectroscopy. The aluminide coating could increase the oxidation resistance of the bare steel by a factor of ˜19. The increase in high-temperature oxidation resistance of the aluminized steel is attributed to the formation of protective alumina scale (α-Al2O3). Although iron oxide nodules grew on the aluminide coating surface, the oxidation rate of the aluminide coatings was very low. After 49 h of oxidation, agglomerates of α-Al2O3 fine grains grew on the rod-shaped FeAl phases.

  17. The Miniaturized Mossbauer Spectrometer MIMOS II for the Asteroid Redirect Mission (ARM): Quantitative Iron Mineralogy and Oxidation States

    NASA Technical Reports Server (NTRS)

    Schroder, Christian; Klingelhofer, Gostar; Morris, Richard V.; Yen, Albert S.; Renz, Franz; Graff, Trevor G.

    2016-01-01

    The miniaturized Mossbauer spectrometer MIMOS II is an off-the-shelf instrument, which has been successfully deployed during NASA's Mars Exploration Rover (MER) mission and was on-board the ESA/UK Beagle 2 Mars lander and the Russian Phobos-Grunt sample return mission. We propose to use a fully-qualified flight-spare MIMOS II instrument available from these missions for in situ asteroid characterization with the Asteroid Redirect Robotic Mission (ARRM).

  18. Development of High Temperature Gas Sensor Technology

    NASA Technical Reports Server (NTRS)

    Hunter, Gary W.; Chen, Liang-Yu; Neudeck, Philip G.; Knight, Dak; Liu, Chung-Chiun; Wu, Quing-Hai; Zhou, Huan-Jun

    1997-01-01

    The measurement of engine emissions is important for their monitoring and control. However, the ability to measure these emissions in-situ is limited. We are developing a family of high temperature gas sensors which are intended to operate in harsh environments such as those in an engine. The development of these sensors is based on progress in two types of technology: (1) The development of SiC-based semiconductor technology; and (2) Improvements in micromachining and microfabrication technology. These technologies are being used to develop point-contact sensors to measure gases which are important in emission control especially hydrogen, hydrocarbons, nitrogen oxides, and oxygen. The purpose of this paper is to discuss the development of this point-contact sensor technology. The detection of each type of gas involves its own challenges in the fields of materials science and fabrication technology. Of particular importance is sensor sensitivity, selectivity, and stability in long-term, high temperature operation. An overview is presented of each sensor type with an evaluation of its stage of development. It is concluded that this technology has significant potential for use in engine applications but further development is necessary.

  19. Nontrivial center dominance in high temperature QCD

    NASA Astrophysics Data System (ADS)

    Ishikawa, K.-I.; Iwasaki, Y.; Nakayama, Yu; Yoshie, T.

    2016-07-01

    We investigate the properties of quarks and gluons above the chiral phase transition temperature Tc, using the renormalization group (RG) improved gauge action and the Wilson quark action with two degenerate quarks mainly on a 323 × 16 lattice. In the one-loop perturbation theory, the thermal ensemble is dominated by the gauge configurations with effectively Z(3) center twisted boundary conditions, making the thermal expectation value of the spatial Polyakov loop take a nontrivial Z(3) center. This is in agreement with our lattice simulation of high temperature quantum chromodynamics (QCD). We further observe that the temporal propagator of massless quarks at extremely high temperature β = 100.0(T ≃ 1058T c) remarkably agrees with the temporal propagator of free quarks with the Z(3) twisted boundary condition for t/Lt ≥ 0.2, but differs from that with the Z(3) trivial boundary condition. As we increase the mass of quarks mq, we find that the thermal ensemble continues to be dominated by the Z(3) twisted gauge field configurations as long as mq ≤ 3.0T and above that the Z(3) trivial configurations come in. The transition is similar to what we found in the departure from the conformal region in the zero-temperature many-flavor conformal QCD on a finite lattice by increasing the mass of quarks.

  20. Evaluation of high temperature capacitor dielectrics

    NASA Technical Reports Server (NTRS)

    Hammoud, Ahmad N.; Myers, Ira T.

    1992-01-01

    Experiments were carried out to evaluate four candidate materials for high temperature capacitor dielectric applications. The materials investigated were polybenzimidazole polymer and three aramid papers: Voltex 450, Nomex 410, and Nomex M 418, an aramid paper containing 50 percent mica. The samples were heat treated for six hours at 60 C and the direct current and 60 Hz alternating current breakdown voltages of both dry and impregnated samples were obtained in a temperature range of 20 to 250 C. The samples were also characterized in terms of their dielectric constant, dielectric loss, and conductivity over this temperature range with an electrical stress of 60 Hz, 50 V/mil present. Additional measurements are underway to determine the volume resistivity, thermal shrinkage, and weight loss of the materials. Preliminary data indicate that the heat treatment of the films slightly improves the dielectric properties with no influence on their breakdown behavior. Impregnation of the samples leads to significant increases in both alternating and direct current breakdown strength. The results are discussed and conclusions made concerning their suitability as high temperature capacitor dielectrics.

  1. High temperature furnace modeling and performance verifications

    NASA Technical Reports Server (NTRS)

    Smith, James E., Jr.

    1992-01-01

    Analytical, numerical, and experimental studies were performed on two classes of high temperature materials processing sources for their potential use as directional solidification furnaces. The research concentrated on a commercially available high temperature furnace using a zirconia ceramic tube as the heating element and an Arc Furnace based on a tube welder. The first objective was to assemble the zirconia furnace and construct parts needed to successfully perform experiments. The 2nd objective was to evaluate the zirconia furnace performance as a directional solidification furnace element. The 3rd objective was to establish a data base on materials used in the furnace construction, with particular emphasis on emissivities, transmissivities, and absorptivities as functions of wavelength and temperature. A 1-D and 2-D spectral radiation heat transfer model was developed for comparison with standard modeling techniques, and were used to predict wall and crucible temperatures. The 4th objective addressed the development of a SINDA model for the Arc Furnace and was used to design sample holders and to estimate cooling media temperatures for the steady state operation of the furnace. And, the 5th objective addressed the initial performance evaluation of the Arc Furnace and associated equipment for directional solidification. Results of these objectives are presented.

  2. The NASA high temperature superconductivity program

    NASA Technical Reports Server (NTRS)

    Sokoloski, Martin M.; Romanofsky, Robert R.

    1990-01-01

    It has been recognized from the onset that high temperature superconductivity held great promise for major advances across a broad range of NASA interests. The current effort is organized around four key areas: communications and data, sensors and cryogenics, propulsion and power, and space materials technology. Recently, laser ablated YBa2Cu3O(7-x) films on LaAIO produced far superior RF characteristics when compared to metallic films on the same substrate. This achievement has enabled a number of unique microwave device applications, such as low insertion loss phase shifters and high Q filters. Melt texturing and melt quenched techniques are being used to produce bulk materials with optimized magnetic properties. These yttrium enriched materials possess enhanced flux pinning characteristics and will lead to prototype cryocooler bearings. Significant progress has also occurred in bolometer and current lead technology. Studies are being conducted to evaluate the effect of high temperature superconducting materials on the performance and life of high power magneto-plasma-dynamic thrusters. Extended studies were also performed to evaluate the benefit of superconducting magnetic energy storage for LEO space station, lunar and Mars mission applications. The project direction and level of effort of the program are also described.

  3. Medium Deep High Temperature Heat Storage

    NASA Astrophysics Data System (ADS)

    Bär, Kristian; Rühaak, Wolfram; Schulte, Daniel; Welsch, Bastian; Chauhan, Swarup; Homuth, Sebastian; Sass, Ingo

    2015-04-01

    Heating of buildings requires more than 25 % of the total end energy consumption in Germany. Shallow geothermal systems for indirect use as well as shallow geothermal heat storage systems like aquifer thermal energy storage (ATES) or borehole thermal energy storage (BTES) typically provide low exergy heat. The temperature levels and ranges typically require a coupling with heat pumps. By storing hot water from solar panels or thermal power stations with temperatures of up to 110 °C a medium deep high temperature heat storage (MDHTS) can be operated on relatively high temperature levels of more than 45 °C. Storage depths of 500 m to 1,500 m below surface avoid conflicts with groundwater use for drinking water or other purposes. Permeability is typically also decreasing with greater depth; especially in the crystalline basement therefore conduction becomes the dominant heat transport process. Solar-thermal charging of a MDHTS is a very beneficial option for supplying heat in urban and rural systems. Feasibility and design criteria of different system configurations (depth, distance and number of BHE) are discussed. One system is designed to store and supply heat (300 kW) for an office building. The required boreholes are located in granodioritic bedrock. Resulting from this setup several challenges have to be addressed. The drilling and completion has to be planned carefully under consideration of the geological and tectonical situation at the specific site.

  4. High temperature electrochemical corrosion rate probes

    SciTech Connect

    Bullard, Sophie J.; Covino, Bernard S., Jr.; Holcomb, Gordon R.; Ziomek-Moroz, M.

    2005-09-01

    Corrosion occurs in the high temperature sections of energy production plants due to a number of factors: ash deposition, coal composition, thermal gradients, and low NOx conditions, among others. Electrochemical corrosion rate (ECR) probes have been shown to operate in high temperature gaseous environments that are similar to those found in fossil fuel combustors. ECR probes are rarely used in energy production plants at the present time, but if they were more fully understood, corrosion could become a process variable at the control of plant operators. Research is being conducted to understand the nature of these probes. Factors being considered are values selected for the Stern-Geary constant, the effect of internal corrosion, and the presence of conductive corrosion scales and ash deposits. The nature of ECR probes will be explored in a number of different atmospheres and with different electrolytes (ash and corrosion product). Corrosion rates measured using an electrochemical multi-technique capabilities instrument will be compared to those measured using the linear polarization resistance (LPR) technique. In future experiments, electrochemical corrosion rates will be compared to penetration corrosion rates determined using optical profilometry measurements.

  5. Borehole Stability in High-Temperature Formations

    NASA Astrophysics Data System (ADS)

    Yan, Chuanliang; Deng, Jingen; Yu, Baohua; Li, Wenliang; Chen, Zijian; Hu, Lianbo; Li, Yang

    2014-11-01

    In oil and gas drilling or geothermal well drilling, the temperature difference between the drilling fluid and formation will lead to an apparent temperature change around the borehole, which will influence the stress state around the borehole and tend to cause borehole instability in high geothermal gradient formations. The thermal effect is usually not considered as a factor in most of the conventional borehole stability models. In this research, in order to solve the borehole instability in high-temperature formations, a calculation model of the temperature field around the borehole during drilling is established. The effects of drilling fluid circulation, drilling fluid density, and mud displacement on the temperature field are analyzed. Besides these effects, the effect of temperature change on the stress around the borehole is analyzed based on thermoelasticity theory. In addition, the relationships between temperature and strength of four types of rocks are respectively established based on experimental results, and thermal expansion coefficients are also tested. On this basis, a borehole stability model is established considering thermal effects and the effect of temperature change on borehole stability is also analyzed. The results show that the fracture pressure and collapse pressure will both increase as the temperature of borehole rises, and vice versa. The fracture pressure is more sensitive to temperature. Temperature has different effects on collapse pressures due to different lithological characters; however, the variation of fracture pressure is unrelated to lithology. The research results can provide a reference for the design of drilling fluid density in high-temperature wells.

  6. Design Considerations for High Temperature Power Inductors

    NASA Technical Reports Server (NTRS)

    Niedra, Janis M.

    2005-01-01

    A uniform B-field approximation model is used to develop design formulas for single-layer wound, toroidal core, ac power inductors that must handle a specified current. Such a geometry is well suited for high temperature, high frequency inductors, where removal of heat from the core becomes critical. Explicit expressions are derived for core radii, core and winding volumes, winding turns and core permeability as functions of a dimensional scaling ratio (S). A limit on the maximum allowed core B-field leads to the result that the minimum core volume is proportional to the permeability, which has a lower bound. Plots versus S are provided for a specific case, to show that good designs can be picked in the overlap regions around the minima in mass and overall size, where the mass and size are relatively flat. Data to 250 C are presented for an MPP core based inductor to show that a quasi-linear, high temperature inductor can be constructed with available materials. A similar development is applied to a toroidal air-core geometry, showing that for the same ratings, such an inductor is considerably bigger and more massive, at least in the single-layer version.

  7. High temperature lined conduits, elbows and tees

    DOEpatents

    De Feo, Angelo; Drewniany, Edward

    1982-01-01

    A high temperature lined conduit comprising, a liner, a flexible insulating refractory blanket around and in contact with the liner, a pipe member around the blanket and spaced therefrom, and castable rigid refractory material between the pipe member and the blanket. Anchors are connected to the inside diameter of the pipe and extend into the castable material. The liner includes male and female slip joint ends for permitting thermal expansion of the liner with respect to the castable material and the pipe member. Elbows and tees of the lined conduit comprise an elbow liner wrapped with insulating refractory blanket material around which is disposed a spaced elbow pipe member with castable refractory material between the blanket material and the elbow pipe member. A reinforcing band is connected to the elbow liner at an intermediate location thereon from which extend a plurality of hollow tubes or pins which extend into the castable material to anchor the lined elbow and permit thermal expansion. A method of fabricating the high temperature lined conduit, elbows and tees is also disclosed which utilizes a polyethylene layer over the refractory blanket after it has been compressed to maintain the refractory blanket in a compressed condition until the castable material is in place. Hot gases are then directed through the interior of the liner for evaporating the polyethylene and setting the castable material which permits the compressed blanket to come into close contact with the castable material.

  8. High-temperature flaw assessment procedure

    SciTech Connect

    Ruggles, M.B. ); Takahashi, Y. ); Ainsworth, R.A. )

    1991-08-01

    Described is the background work performed jointly by the Electric Power Research Institute in the United States, the Central Research Institute of Electric Power Industry in Japan and Nuclear Electric plc in the United Kingdom with the purpose of developing a high-temperature flaw assessment procedure for reactor components. Existing creep-fatigue crack-growth models are reviewed, and the most promising methods are identified. Sources of material data are outlined, and results of the fundamental deformation and crack-growth tests are discussed. Results of subcritical crack-growth exploratory tests, creep-fatigue crack-growth tests under repeated thermal transient conditions, and exploratory failure tests are presented and contrasted with the analytical modeling. Crack-growth assessment methods are presented and applied to a typical liquid-metal reactor component. The research activities presented herein served as a foundation for the Flaw Assessment Guide for High-Temperature Reactor Components Subjected to Creep-Fatigue Loading published separately. 30 refs., 108 figs., 13 tabs.

  9. The moon as a high temperature condensate

    NASA Technical Reports Server (NTRS)

    Anderson, D. L.

    1972-01-01

    The accretion during condensation mechanism is used to explain the differences in composition of the terrestrial planets and the moon. Many of the properties of the moon, including the enrichment in Ca, Al, Ti, U, Th, Ba, Sr and the REE and the depletion in Fe, Rb, K, Na and other volatiles can be understood if the moon represents a high temperature condensate from the solar nebula. Thermodynamic calculations show that Ca, Al and Ti rich compounds condense first in a cooling nebula. The high temperature mineralogy is gehlenite, spinel perovskite, Ca-Al-rich pyroxenes and anorthite. The model is consistent with extensive early melting, shallow melting at 3 A.E. and with presently high speed internal temperatures. It is predicted that the outer 250 km is rich in plagioclase and FeO. The low iron content of the interior in this model raises the interior temperatures estimated from electrical conductivity by some 800 C. The lunar crust is 80 percent gabbroic anorthosite, 20 percent basalt and is about 250-270 km thick. The lunar mantle is probably composed of spinel, merwinite and diopside with a density of 3.4 g/cu cm.

  10. Evaluation of high temperature capacitor dielectrics

    NASA Astrophysics Data System (ADS)

    Hammoud, Ahmad N.; Myers, Ira T.

    Experiments were carried out to evaluate four candidate materials for high temperature capacitor dielectric applications. The materials investigated were polybenzimidazole polymer and three aramid papers: Voltex 450, Nomex 410, and Nomex M 418, an aramid paper containing 50 percent mica. The samples were heat treated for six hours at 60 C and the direct current and 60 Hz alternating current breakdown voltages of both dry and impregnated samples were obtained in a temperature range of 20 to 250 C. The samples were also characterized in terms of their dielectric constant, dielectric loss, and conductivity over this temperature range with an electrical stress of 60 Hz, 50 V/mil present. Additional measurements are underway to determine the volume resistivity, thermal shrinkage, and weight loss of the materials. Preliminary data indicate that the heat treatment of the films slightly improves the dielectric properties with no influence on their breakdown behavior. Impregnation of the samples leads to significant increases in both alternating and direct current breakdown strength. The results are discussed and conclusions made concerning their suitability as high temperature capacitor dielectrics.

  11. Pressure sensor for high-temperature liquids

    DOEpatents

    Forster, George A.

    1978-01-01

    A pressure sensor for use in measuring pressures in liquid at high temperatures, especially such as liquid sodium or liquid potassium, comprises a soft diaphragm in contact with the liquid. The soft diaphragm is coupled mechanically to a stiff diaphragm. Pressure is measured by measuring the displacment of both diaphragms, typically by measuring the capacitance between the stiff diaphragm and a fixed plate when the stiff diaphragm is deflected in response to the measured pressure through mechanical coupling from the soft diaphragm. Absolute calibration is achieved by admitting gas under pressure to the region between diaphragms and to the region between the stiff diaphragm and the fixed plate, breaking the coupling between the soft and stiff diaphragms. The apparatus can be calibrated rapidly and absolutely.

  12. High temperature experiment for accelerator inertial fusion

    SciTech Connect

    Lee, E.P.

    1985-05-01

    The High Temperature Experiment (HTE) is intended to produce temperatures of 50 to 100 eV in solid density targets driven by heavy ion beams from a multiple beam induction linac. The fundamental variables (particle species, energy, number of beamlets, current and pulse length) must be fixed to achieve the temperature at minimum cost, subject to criteria of technical feasibility and relevance to the development of a Fusion Driver. The conceptual design begins with an assumed (radiation-limited) target temperature and uses limitations due to particle range, beamlet perveance, and target disassembly to bound the allowable values of mass number (A) and energy (E). An accelerator model is then applied to determine the minimum length accelerator, which is a guide to total cost. The accelerator model takes into account limits on transportable charge, maximum gradient, core mass per linear meter, and head-to-tail momentum variation within a pulse.

  13. High modulus high temperature glass fibers

    NASA Technical Reports Server (NTRS)

    Bacon, J. F.

    1973-01-01

    The search for a new high-modulus, high-temperature glass fiber involved the preparation of 500 glass compositions lying in 12 glass fields. These systems consisted primarily of low atomic number oxides and rare-earth oxides. Direct optical measurements of the kinetics of crystallization of the cordierite-rare earth system, for example, showed that the addition of rare-earth oxides decreased the rate of formation of cordierite crystals. Glass samples prepared from these systems proved that the rare-earth oxides made large specific contributions to the Young's modulus of the glasses. The best glasses have moduli greater than 21 million psi, the best glass fibers have moduli greater than 18 million psi, and the best glass fiber-epoxy resin composites have tensile strengths of 298,000 psi, compressive strengths of at least 220,000 psi, flexural strengths of 290,000 psi, and short-beam shear strengths of almost 17,000 psi.

  14. Strain sensing technology for high temperature applications

    NASA Technical Reports Server (NTRS)

    Williams, W. Dan

    1993-01-01

    This review discusses the status of strain sensing technology for high temperature applications. Technologies covered are those supported by NASA such as required for applications in hypersonic vehicles and engines, advanced subsonic engines, as well as material and structure development. The applications may be at temperatures of 540 C (1000 F) to temperatures in excess of 1400 C (2500 F). The most promising technologies at present are the resistance strain gage and remote sensing schemes. Resistance strain gages discussed include the BCL gage, the LaRC compensated gage, and the PdCr gage. Remote sensing schemes such as laser based speckle strain measurement, phase-shifling interferometry, and x-ray extensometry are discussed. Present status and limitations of these technologies are presented.

  15. High temperature NASP engine seal development

    NASA Astrophysics Data System (ADS)

    This video details research being conducted at the Lewis Research Center on high temperature engine seal design for the National Aerospace Plane. To maximize the speed, the jets on the NASP extract oxygen from the air rather than carry large liquid fuel tanks; this creates temperatures within the jet of over 5000 F. To prevent these potentially explosive gases from escaping, researchers are developing new technologies for use in the engine seals. Two examples explained are the ceramic wafer seal and the braided ceramic rope seal. Computer simulations and laboratory footage are used to illustrate the workings of these seals. Benefits for other aerospace and industrial applications, as well as for the space shuttle, are explored.

  16. Fail Safe, High Temperature Magnetic Bearings

    NASA Technical Reports Server (NTRS)

    Minihan, Thomas; Palazzolo, Alan; Kim, Yeonkyu; Lei, Shu-Liang; Kenny, Andrew; Na, Uhn Joo; Tucker, Randy; Preuss, Jason; Hunt, Andrew; Carter, Bart; Kiraly, L. J. (Technical Monitor)

    2002-01-01

    This paper contributes to the magnetic bearing literature in two distinct areas: high temperature and redundant actuation. Design considerations and test results are given for the first published combined 538 C (1000 F) high speed rotating test performance of a magnetic bearing. Secondly, a significant extension of the flux isolation based, redundant actuator control algorithm is proposed to eliminate the prior deficiency of changing position stiffness after failure. The benefit of the novel extension was not experimentally demonstrated due to a high active stiffness requirement. In addition, test results are given for actuator failure tests at 399 C (750 F), 12,500 rpm. Finally, simulation results are presented confirming the experimental data and validating the redundant control algorithm.

  17. Stable Vanadium Isotope Fractionation at High Temperatures

    NASA Astrophysics Data System (ADS)

    Prytulak, J.; Parkinson, I. J.; Savage, P. S.; Nielsen, S. G.; Halliday, A. N.

    2011-12-01

    Vanadium is a redox sensitive transition metal existing in multiple valence states at terrestrial conditions. Stable vanadium isotopes (reported as δ51V in % relative to an Alfa Aesar standard [1]) are a potentially powerful tracer of oxidation-reduction processes. However, the determination of δ51V is analytically challenging, primarily due to the extreme abundance ratio between the only two stable isotopes (51V/50V ~ 400) and, also, significant isobaric interferences of 50Ti and 50Cr on the minor 50V isotope. We have developed the first method able to determine δ51V to a precision (2 s.d. ~ 0.15%, [1,2]) that enables application of this isotope system to geological processes. To usefully investigate high temperature processes using vanadium isotopes, knowledge of the isotope composition and range of values present in the ambient mantle is required. Here we discuss the first δ51V measured in igneous materials encompassing peridotites, MORB, and primitive mantle-derived melts such as picrites. This first dataset provides a preliminary reconnaissance of the magnitude of natural fractionation. We find little isotope fractionation in suites of peridotites and MORB (< 0.5 %). However, the small but analytically significant variation appears to be related to secondary processes, with extremely altered peridotites consistently displaying slightly heavier isotope compositions. We find no resolvable δ51V variation between fresh MORB glass and fresh peridotite. Intriguingly, a suite of subduction-related peridotites from the Mariana forearc, previously characterized for fO2 [3], do not display the predicted co-variation between δ51V and fO2, but instead also have compositions identical to MORB glass. This nominally supports recent indications that there is limited difference in the oxygen fugacity of the MORB source and the subarc mantle wedge [e.g., 4, 5]. Finally, we observe large δ51V variations (~ 2 %) in a suite of evolving lavas from Hekla volcano, Iceland

  18. Rechargeable high-temperature batteries [Book Chapter

    SciTech Connect

    Cairns, Elton J.

    1981-01-01

    There has been growing research and development effort in the area of high-specific-energy, high-specific-power rechargeable batteries since the mid 1960s and it has been used in electric vehicles, electric utility networks, and solar- and wind-powered electric generator systems. Nonaqueous systems have been found to be the most attractive candidates for the above relatively large-scale applications. Only the high-temperature cells offer the attractive combination of features sought for the cited applications: a specific energy above 100 Wh/kg, a specific power above 100 W/kg, a cycle life in excess of 500 cycles (at 100% depth of discharge), and a projected cost of less than $50† per kWh of energy storage capability.

  19. High temperature dimensional reduction in Snyder space

    NASA Astrophysics Data System (ADS)

    Nozari, K.; Hosseinzadeh, V.; Gorji, M. A.

    2015-11-01

    In this paper, we formulate the statistical mechanics in Snyder space that supports the existence of a minimal length scale. We obtain the corresponding invariant Liouville volume which properly determines the number of microstates in the semiclassical regime. The results show that the number of accessible microstates drastically reduces at the high energy regime such that there is only one degree of freedom for a particle. Using the Liouville volume, we obtain the deformed partition function and we then study the thermodynamical properties of the ideal gas in this setup. Invoking the equipartition theorem, we show that 2/3 of the degrees of freedom freeze at the high temperature regime when the thermal de Broglie wavelength becomes of the order of the Planck length. This reduction of the number of degrees of freedom suggests an effective dimensional reduction of the space from 3 to 1 at the Planck scale.

  20. Low to high temperature energy conversion system

    NASA Technical Reports Server (NTRS)

    Miller, C. G. (Inventor)

    1977-01-01

    A method for converting heat energy from low temperature heat sources to higher temperature was developed. It consists of a decomposition chamber in which ammonia is decomposed into hydrogen and nitrogen by absorbing heat of decomposition from a low temperature energy source. A recombination reaction then takes place which increases the temperature of a fluid significantly. The system is of use for the efficient operation of compact or low capital investment turbine driven electrical generators, or in other applications, to enable chemical reactions that have a critical lower temperature to be used. The system also recovers heat energy from low temperature heat sources, such as solar collectors or geothermal sources, and converts it to high temperatures.

  1. Precision control of high temperature furnaces

    SciTech Connect

    Pollock, G.G.

    1994-12-31

    It is an object of the present invention to provide precision control of high temperature furnaces. It is another object of the present invention to combine the power of two power supplies of greatly differing output capacities in a single furnace. This invention combines two power supplies to control a furnace. A main power supply heats the furnace in the traditional manner, while the power from the auxiliary supply is introduced as a current flow through charged particles existing due to ionized gas or thermionic emission. The main power supply provides the bulk heating power and the auxiliary supply provides a precise and fast power source such that the precision of the total power delivered to the furnace is improved. Further, this invention comprises a means for high speed measurement of temperature of the process by the method of measuring the amount of current flow in a deliberately induced charged particle current.

  2. Parameters of high-temperature superconducting transformers

    NASA Astrophysics Data System (ADS)

    Volkov, E. P.; Dzhafarov, E. A.

    2015-12-01

    Parameters of the high-temperature superconducting (HTSC) transformer with a core-type magnetic circuit and with coaxial and symmetrical interleaved windings made of the first-generation HTSC wire with a localized magnetic field are considered. The parameters of the most widespread core-type transformer with a coaxial HTSC winding are compared with those of a conventional transformer with a copper wire winding. Advantages of the HTSC transformers, such as reduction in the leakage inductive reactance and the HTSC winding's cross section, volume, and mass, as compared with the same parameters of conventional transformers with a copper wire winding are demonstrated. The efficiency of the HTSC transformers has proven to be determined predominantly by the core loss. In order to increase the efficiency of the HTSC transformer, it is proposed to use the amorphous electrical steel as the material of its magnetic circuit.

  3. Multilayer ultra-high-temperature ceramic coatings

    DOEpatents

    Loehman, Ronald E.; Corral, Erica L.

    2012-03-20

    A coated carbon-carbon composite material with multiple ceramic layers to provide oxidation protection from ultra-high-temperatures, where if the carbon-carbon composite material is uninhibited with B.sub.4C particles, then the first layer on the composite material is selected from ZrB.sub.2 and HfB.sub.2, onto which is coated a layer of SiC coated and if the carbon-carbon composite material is inhibited with B.sub.4C particles, then protection can be achieved with a layer of SiC and a layer of either ZrB.sub.2 and HfB.sub.2 in any order.

  4. Creep resistant high temperature martensitic steel

    SciTech Connect

    Hawk, Jeffrey A.; Jablonski, Paul D.; Cowen, Christopher J.

    2015-11-13

    The disclosure provides a creep resistant alloy having an overall composition comprised of iron, chromium, molybdenum, carbon, manganese, silicon, nickel, vanadium, niobium, nitrogen, tungsten, cobalt, tantalum, boron, and potentially additional elements. In an embodiment, the creep resistant alloy has a molybdenum equivalent Mo(eq) from 1.475 to 1.700 wt. % and a quantity (C+N) from 0.145 to 0.205. The overall composition ameliorates sources of microstructural instability such as coarsening of M.sub.23C.sub.6 carbides and MX precipitates, and mitigates or eliminates Laves and Z-phase formation. A creep resistant martensitic steel may be fabricated by preparing a melt comprised of the overall composition followed by at least austenizing and tempering. The creep resistant alloy exhibits improved high-temperature creep strength in the temperature environment of around 650.degree. C.

  5. High temperature coatings for gas turbines

    DOEpatents

    Zheng, Xiaoci Maggie

    2003-10-21

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

  6. Improved high-temperature resistant matrix resins

    NASA Technical Reports Server (NTRS)

    Green, H. E.; Chang, G. E.; Wright, W. F.; Ueda, K.; Orell, M. K.

    1989-01-01

    A study was performed with the objective of developing matrix resins that exhibit improved thermo-oxidative stability over state-of-the-art high temperature resins for use at temperatures up to 644 K (700 F) and air pressures up to 0.7 MPa (100 psia). The work was based upon a TRW discovered family of polyimides currently licensed to and marketed by Ethyl Corporation as EYMYD(R) resins. The approach investigated to provide improved thermo-oxidative properties was to use halogenated derivatives of the diamine, 2, 2-bis (4-(4-aminophenoxy)phenyl) hexafluoropropane (4-BDAF). Polyimide neat resins and Celion(R) 12,000 composites prepared from fluorine substituted 4-BDAF demonstrated unexpectedly lower glass transition temperatures (Tg) and thermo-oxidative stabilities than the baseline 4-BDAF/PMDA polymer.

  7. Two High-Temperature Foil Journal Bearings

    NASA Technical Reports Server (NTRS)

    Zak, Michail

    2006-01-01

    An enlarged, high-temperature-compliant foil bearing has been built and tested to demonstrate the feasibility of such bearings for use in aircraft gas turbine engines. Foil bearings are attractive for use in some machines in which (1) speeds of rotation, temperatures, or both exceed maximum allowable values for rolling-element bearings; (2) conventional lubricants decompose at high operating temperatures; and/or (3) it is necessary or desirable not to rely on conventional lubrication systems. In a foil bearing, the lubricant is the working fluid (e.g., air or a mixture of combustion gases) in the space between the journal and the shaft in the machine in which the bearing is installed.

  8. Aerospace applications of high temperature superconductivity

    NASA Technical Reports Server (NTRS)

    Connolly, D. J.; Heinen, V. O.; Aron, P. R.; Lazar, J.; Romanofsky, Robert R.

    1990-01-01

    A review is presented of all the applications that are part of the NASA program to develop space technology capitalizing on the potential benefit of high temperature superconducting materials. The applications in three major areas are being pursued: sensors and cryogenic systems, space communications, and propulsion and power systems. This review places emphasis on space communications applications and the propulsion and power applications. It is concluded that the power and propulsion applications will eventually be limited by structural considerations rather than by the availability of suitable superconductors. A cursory examination of structural limitations implied by the virial theorem suggested that there is an upper limit to the size of high field magnetic systems that are feasible in space.

  9. High temperature superconductivity space experiment (HTSSE)

    NASA Technical Reports Server (NTRS)

    Ritter, J. C.; Nisenoff, M.; Price, G.; Wolf, S. A.

    1991-01-01

    An experiment dealing with high-temperature superconducting devices and components in space is discussed. A variety of devices (primarily passive microwave and millimeter-wave components) has been procured and will be integrated with a cryogenic refrigerating and data acquisition system to form the space package, which will be launched in late 1992. This space experiment is expected to demonstrate that this technology is sufficiently robust to survive the space environment and that the technology has the potential to improve the operation of space systems significantly. The devices for the initial launch have been evaluated electrically, thermally, and mechanically, and will be integrated into the final space package early in 1991. The performance of the devices is summarized, and some potential applications of this technology in space systems are outlined.

  10. High Temperature Battery for Drilling Applications

    SciTech Connect

    Josip Caja

    2009-12-31

    In this project rechargeable cells based on the high temperature electrochemical system Na/beta''-alumina/S(IV) in AlCl3/NaCl were developed for application as an autonomous power source in oil/gas deep drilling wells. The cells operate in the temperature range from 150 C to 250 C. A prototype DD size cell was designed and built based on the results of finite element analysis and vibration testing. The cell consisted of stainless steel case serving as anode compartment with cathode compartment installed in it and a seal closing the cell. Critical element in cell design and fabrication was hermetically sealing the cell. The seal had to be leak tight, thermally and vibration stable and compatible with electrode materials. Cathode compartment was built of beta''-alumina tube which served as an electrolyte, separator and cathode compartment.

  11. Filter unit for use at high temperatures

    DOEpatents

    Ciliberti, David F.; Lippert, Thomas E.

    1988-01-01

    A filtering unit for filtering particulates from high temperature gases uses a spiral ceramic spring to bias a ceramic, tubular filter element into sealing contact with a flange about an aperture of a metallic tube sheet. The ceramic spiral spring may contact the upper edge of the filter element and be restrained by a stop member spaced from one end of the tube sheet, or the spring may contact the bottom of the filter element and be restrained by a support member spaced from the opposite end of the tube sheet. The stop member and support member are adjustably secured to the tube sheet. A filtering system uses the ceramic spiral spring to bias a plurality of ceramic, tubular filter elements in a respective plurality of apertures in a tube sheet which divides a vessel into upper and lower enclosed sections.

  12. Quark number fluctuations at high temperatures

    SciTech Connect

    Petreczky, P.; Hegde, P.; Velytsky, A.

    2009-11-01

    We calculate the second, fourth and sixth order quark number fluctuations in the deconfined phase of 2+1 flavor QCD using lattices with temporal extent N{sub t} = 4,6,8 and 12. We consider light, strange and charm quarks. We use p4 action for valence quarks and gauge configurations generated with p4 action with physical value of the strange quark mass and light quark mass m{sub q} = 0.1 m{sub s} generated by the RBC-Bielefeld collaboration. We observe that for all quark masses the quark number fluctuations rapidly get close to the corresponding ideal gas limits. We compare our results to predictions of a quasi-particle model and resummed high temperature perturbative calculations. We also investigate correlations among different flavor channels.

  13. Gravimeter using high-temperature superconductor bearing.

    SciTech Connect

    Hull, J. R.

    1998-09-11

    We have developed a sensitive gravimeter concept that uses an extremely low-friction bearing based on a permanent magnet (PM) levitated over a high-temperature superconductor (HTS). A mass is attached to the PM by means of a cantilevered beam, and the combination of PM and HTS forms a bearing platform that has low resistance to rotational motion but high resistance to horizontal, vertical, or tilting motion. The combination acts as a low-loss torsional pendulum that can be operated in any orientation. Gravity acts on the cantilevered beam and attached mass, accelerating them. Variations in gravity can be detected by time-of-flight acceleration, or by a control coil or electrode that would keep the mass stationary. Calculations suggest that the HTS gravimeter would be as sensitive as present-day superconducting gravimeters that need cooling to liquid helium temperatures, but the HTS gravimeter needs cooling only to liquid nitrogen temperatures.

  14. High pressure and high temperature apparatus

    DOEpatents

    Voronov, Oleg A.

    2005-09-13

    A design for high pressure/high temperature apparatus and reaction cell to achieve .about.30 GPa pressure in .about.1 cm volume and .about.100 GPa pressure in .about.1 mm volumes and 20-5000.degree. C. temperatures in a static regime. The device includes profiled anvils (28) action on a reaction cell (14, 16) containing the material (26) to be processed. The reaction cell includes a heater (18) surrounded by insulating layers and screens. Surrounding the anvils are cylindrical inserts and supporting rings (30-48) whose hardness increases towards the reaction cell. These volumes may be increased considerably if applications require it, making use of presses that have larger loading force capability, larger frames and using larger anvils.

  15. Turbine vane with high temperature capable skins

    DOEpatents

    Morrison, Jay A.

    2012-07-10

    A turbine vane assembly includes an airfoil extending between an inner shroud and an outer shroud. The airfoil can include a substructure having an outer peripheral surface. At least a portion of the outer peripheral surface is covered by an external skin. The external skin can be made of a high temperature capable material, such as oxide dispersion strengthened alloys, intermetallic alloys, ceramic matrix composites or refractory alloys. The external skin can be formed, and the airfoil can be subsequently bi-cast around or onto the skin. The skin and the substructure can be attached by a plurality of attachment members extending between the skin and the substructure. The skin can be spaced from the outer peripheral surface of the substructure such that a cavity is formed therebetween. Coolant can be supplied to the cavity. Skins can also be applied to the gas path faces of the inner and outer shrouds.

  16. High-Temperature Solid Lubricant Coating

    NASA Technical Reports Server (NTRS)

    DellaCorte, Christopher; Edmonds, Brian J.

    2010-01-01

    NASA PS400 is a solid lubricant coating invented for high-temperature tribological applications. This plasma-sprayed coating is a variant of the previously patented PS304 coating, and has been formulated to provide higher density, smoother surface finish, and better dimensional stability. This innovation is a new composite material that provides a means to reduce friction and wear in mechanical components. PS400 is a blend of a nickel-molybdenum binder, chrome oxide hardener, silver lubricant, and barium fluoride/calcium fluoride eutectic lubricant that can either be sprayed or deposited by other means, such as powder metallurgy. The resulting composite material is then finished by grinding and polishing to produce a smooth, self-lubricating surface.

  17. Ultra-High Temperature Ceramic (UHTC) Development

    NASA Technical Reports Server (NTRS)

    Johnson, Sylvia; Ellerby, Don

    2001-01-01

    During the last decade, NASA Ames has been developing new, Ultra-High Temperature Ceramic (UHTC) materials for Thermal Protection Systems applications. The UHTC s are a family of materials including compositions of HfE32 and ZrB2 with a Sic second phase. A collaboration with Glenn was recently initiated to evaluate the viability of some UHTC materials that had been produced by an outside vendor for use in gas turbine en,@ne environments. Results from this collaboration have indicated that compositions based on HfB2 show the most promise, among the UHTC compositions evaluated, for use in these environments. Work at ARC has been initiated to fabricate these materials in-house and evaluate methods of improving their properties for use in engine environments.

  18. Low toxicity high temperature PMR polyimide

    NASA Technical Reports Server (NTRS)

    Pater, Ruth H. (Inventor)

    1992-01-01

    In-situ polymerization of monomer reactants (PMR) type polyimides constitute an important class of ultra high performance composite matrix resins. PMR-15 is the best known and most widely used PMR polyimide. An object of the present invention is to provide a substantially improved high temperature PMR-15 system that exhibits better processability, toughness, and thermo-oxidative stability than PMR-15, as well as having a low toxicity. Another object is to provide new PMR polyimides that are useful as adhesives, moldings, and composite matrices. By the present invention, a new PMR polyimide comprises a mixture of the following compounds: 3,4'-oxydianiline (3,4'-ODA), NE, and BTDE which are then treated with heat. This PMR was designated LaRC-RP46 and has a broader processing window, better reproducibility of high quality composite parts, better elevated temperature mechanical properties, and higher retention of mechanical properties at an elevated temperature, particularly, at 371 C.

  19. High-Temperature Graphite/Phenolic Composite

    NASA Technical Reports Server (NTRS)

    Seal, Ellis C.; Bodepudi, Venu P.; Biggs, Robert W., Jr.; Cranston, John A.

    1995-01-01

    Graphite-fiber/phenolic-resin composite material retains relatively high strength and modulus of elasticity at temperatures as high as 1,000 degrees F. Costs only 5 to 20 percent as much as refractory materials. Fabrication composite includes curing process in which application of full autoclave pressure delayed until after phenolic resin gels. Curing process allows moisture to escape, so when composite subsequently heated in service, much less expansion of absorbed moisture and much less tendency toward delamination. Developed for nose cone of external fuel tank of Space Shuttle. Other potential aerospace applications for material include leading edges, parts of nozzles, parts of aircraft engines, and heat shields. Terrestrial and aerospace applications include structural firewalls and secondary structures in aircraft, spacecraft, and ships. Modified curing process adapted to composites of phenolic with other fiber reinforcements like glass or quartz. Useful as high-temperature circuit boards and electrical insulators.

  20. Compliant high temperature seals for dissimilar materials

    DOEpatents

    Rynders, Steven Walton; Minford, Eric; Tressler, Richard Ernest; Taylor, Dale M.

    2001-01-01

    A high temperature, gas-tight seal is formed by utilizing one or more compliant metallic toroidal ring sealing elements, where the applied pressure serves to activate the seal, thus improving the quality of the seal. The compliant nature of the sealing element compensates for differences in thermal expansion between the materials to be sealed, and is particularly useful in sealing a metallic member and a ceramic tube art elevated temperatures. The performance of the seal may be improved by coating the sealing element with a soft or flowable coating such as silver or gold and/or by backing the sealing element with a bed of fine powder. The material of the sealing element is chosen such that the element responds to stress elastically, even at elevated temperatures, permitting the seal to operate through multiple thermal cycles.

  1. Secondary calcium solid electrolyte high temperature battery

    NASA Astrophysics Data System (ADS)

    Sammells, A. F.; Schumacher, B.

    1986-01-01

    The application of polycrystalline Ca(2+) conducting beta-double prime alumina solid electrolytes to a new type of high temperature battery is investigated, experimentally. The negative electrode in the battery consisted of a calcium-silicon alloy whose redox electrochemistry was mediated by the solid electrolyte via molten salt eutectic CaCl2 (51.4 m/o), and CaI2 (mp 550 C). The molten salt and the calcium alloy material were separated from the positive active material via the Ca2 Ca(2+) conducting polycrystalline electrolyte. The positive electrode consisted of a solid-state matrix having related crystallographic structure. The electrochemical reversibility of the cells was measured at 580 C. The charge-discharge characteristics of the cells are plotted vs. time in a graph.

  2. High temperature solder device for flat cables

    NASA Technical Reports Server (NTRS)

    Haehner, Carl L. (Inventor)

    1992-01-01

    A high temperature solder device for flat cables includes a microwelder, an anvil which acts as a heat sink and supports a flexible flat ribbon cable that is to be connected to a multiple pin connector. The microwelder is made from a modified commercially available resistance welding machine such as the Split Tip Electrode microwelder by Weltek, which consists of two separate electrode halves with a removable dielectric spacer in between. The microwelder is not used to weld the items together, but to provide a controlled compressive force on, and energy pulse to, a solder preform placed between a pin of the connector and a conductor of the flexible flat ribbon cable. When the microwelder is operated, an electric pulse will flow down one electrode, through the solder preform and back up the other electrode. This pulse of electrical energy will cause the solder preform to heat up and melt, joining the pin and conductor.

  3. High temperature insulation for ceramic matrix composites

    DOEpatents

    Merrill, Gary B.; Morrison, Jay Alan

    2000-01-01

    A ceramic composition is provided to insulate ceramic matrix composites under high temperature, high heat flux environments. The composite comprises a plurality of hollow oxide-based spheres of varios dimentions, a phosphate binder, and at least one oxide filler powder, whereby the phosphate binder partially fills gaps between the spheres and the filler powders. The spheres are situated in the phosphate binder and the filler powders such that each sphere is in contact with at least one other sphere. The spheres may be any combination of Mullite spheres, Alumina spheres, or stabilized Zirconia spheres. The filler powder may be any combination of Alumina, Mullite, Ceria, or Hafnia. Preferably, the phosphate binder is Aluminum Ortho-Phosphate. A method of manufacturing the ceramic insulating composition and its application to CMC substates are also provided.

  4. High temperature insulation for ceramic matrix composites

    DOEpatents

    Merrill, Gary B.; Morrison, Jay Alan

    2004-01-13

    A ceramic composition is provided to insulate ceramic matrix composites under high temperature, high heat flux environments. The composition comprises a plurality of hollow oxide-based spheres of various dimensions, a phosphate binder, and at least one oxide filler powder, whereby the phosphate binder partially fills gaps between the spheres and the filler powders. The spheres are situated in the phosphate binder and the filler powders such that each sphere is in contact with at least one other sphere. The spheres may be any combination of Mullite spheres, Alumina spheres, or stabilized Zirconia spheres. The filler powder may be any combination of Alumina, Mullite, Ceria, or Hafnia. Preferably, the phosphate binder is Aluminum Ortho-Phosphate. A method of manufacturing the ceramic insulating composition and its application to CMC substrates are also provided.

  5. High temperature insulation for ceramic matrix composites

    DOEpatents

    Merrill, Gary B.; Morrison, Jay Alan

    2001-01-01

    A ceramic composition is provided to insulate ceramic matrix composites under high temperature, high heat flux environments. The composition comprises a plurality of hollow oxide-based spheres of various dimensions, a phosphate binder, and at least one oxide filler powder, whereby the phosphate binder partially fills gaps between the spheres and the filler powders. The spheres are situated in the phosphate binder and the filler powders such that each sphere is in contact with at least one other sphere. The spheres may be any combination of Mullite spheres, Alumina spheres, or stabilized Zirconia spheres. The filler powder may be any combination of Alumina, Mullite, Ceria, or Hafnia. Preferably, the phosphate binder is Aluminum Ortho-Phosphate. A method of manufacturing the ceramic insulating composition and its application to CMC substrates are also provided.

  6. High temperature chemically resistant polymer concrete

    DOEpatents

    Sugama, T.; Kukacka, L.E.

    High temperature chemically resistant, non-aqueous polymer concrete composites consist of about 12 to 20% by weight of a water-insoluble polymer binder. The binder is polymerized in situ from a liquid vinyl-type monomer or mixture of vinyl containing monomers such as triallylcyanurate, styrene, acrylonitrile, acrylamide, methacrylamide, methyl-methacrylate, trimethylolpropane trimethacrylate and divinyl benzene. About 5 to 40% by weight of a reactive inorganic filler selected from the group consisting of tricalcium silicate and dicalcium silicate and mixtures containing less than 2% free lime, and about 48 to 83% by weight of silica sand/ and a free radical initiator such as di-tert-butyl peroxide, azobisisobutyronitrile, benzoyl peroxide, lauryl peroxide, other orgaic peroxides and combinations to initiate polymerization of the monomer in the presence of the inorganic filers are used.

  7. Thermoelectric properties by high temperature annealing

    NASA Technical Reports Server (NTRS)

    Ren, Zhifeng (Inventor); Chen, Gang (Inventor); Kumar, Shankar (Inventor); Lee, Hohyun (Inventor)

    2009-01-01

    The present invention generally provides methods of improving thermoelectric properties of alloys by subjecting them to one or more high temperature annealing steps, performed at temperatures at which the alloys exhibit a mixed solid/liquid phase, followed by cooling steps. For example, in one aspect, such a method of the invention can include subjecting an alloy sample to a temperature that is sufficiently elevated to cause partial melting of at least some of the grains. The sample can then be cooled so as to solidify the melted grain portions such that each solidified grain portion exhibits an average chemical composition, characterized by a relative concentration of elements forming the alloy, that is different than that of the remainder of the grain.

  8. High temperature low friction surface coating

    DOEpatents

    Bhushan, Bharat

    1980-01-01

    A high temperature, low friction, flexible coating for metal surfaces which are subject to rubbing contact includes a mixture of three parts graphite and one part cadmium oxide, ball milled in water for four hours, then mixed with thirty percent by weight of sodium silicate in water solution and a few drops of wetting agent. The mixture is sprayed 12-15 microns thick onto an electro-etched metal surface and air dried for thirty minutes, then baked for two hours at 65.degree. C. to remove the water and wetting agent, and baked for an additional eight hours at about 150.degree. C. to produce the optimum bond with the metal surface. The coating is afterwards burnished to a thickness of about 7-10 microns.

  9. Opacification of high temperature fibrous insulation

    NASA Technical Reports Server (NTRS)

    Miller, W. C.; Collins, J. O.

    1984-01-01

    A study was conducted to determine the merits of adding particulate materials to silica fiber felts to increase their resistance to the passage of thermal radiation. Laboratory samples containing 5, 10, and 15 percent of chromium oxide, silicon carbide, and titanium dioxide were prepared and evaluated in accordance with ASTM C-518 thermal conductivity test method at 425 C (800 F) mean temperature. The titania particles averaging 3-4 micrometers in diameter were found to be the most effective. This was followed by a short plant run, in order to confirm the initial results on the laboratory samples. These samples were tested according to ASTM C-201 High Temperature Calorimeter from 93 C to 760 C (200 F to 1400 F) mean temperature. The ten percent by weight of titania resulted in an optimum effectiveness, and reduced the conductivity over 20% at 760 C (1400 F).

  10. Heterogeneous metasurface for high temperature selective emission

    SciTech Connect

    Woolf, D. Hensley, J.; Cederberg, J. G.; Bethke, D. T.; Grine, A. D.; Shaner, E. A.

    2014-08-25

    We demonstrate selective emission from a heterogeneous metasurface that can survive repeated temperature cycling at 1300 K. Simulations, fabrication, and characterization were performed for a cross-over-a-backplane metasurface consisting of platinum and alumina layers on a sapphire substrate. The structure was stabilized for high temperature operation by an encapsulating alumina layer. The geometry was optimized for integration into a thermophotovoltaic (TPV) system, and was designed to have its emissivity matched to the external quantum efficiency spectrum of 0.6 eV InGaAs TPV material. We present spectral measurements of the metasurface that result in a predicted 22% optical-to-electrical power conversion efficiency in a simplified model at 1300 K. Furthermore, this broadly adaptable selective emitter design can be easily integrated into full-scale TPV systems.

  11. Permanent magnets composed of high temperature superconductors

    NASA Technical Reports Server (NTRS)

    Weinstein, Roy; Chen, In-Gann; Liu, Jay; Lau, Kwong

    1991-01-01

    A study of persistent, trapped magnetic field has been pursued with high-temperature superconducting (HTS) materials. The main effort is to study the feasibility of utilization of HTS to fabricate magnets for various devices. The trapped field, when not in saturation, is proportional to the applied field. Thus, it should be possible to replicate complicated field configurations with melt-textured YBa2Cu3O7 (MT-Y123) material, bypassing the need for HTS wires. Presently, materials have been developed from which magnets of 1.5 T, at 77 K, can be fabricated. Much higher field is available at lower operating temperature. Stability of a few percent per year is readily attainable. Results of studies on prototype motors and minimagnets are reported.

  12. High temperature superconductors for magnetic suspension applications

    NASA Technical Reports Server (NTRS)

    Mcmichael, C. K.; Cooley, R. S.; Chen, Q. Y.; Ma, K. B.; Lamb, M. A.; Meng, R. L.; Chu, C. W.; Chu, W. K.

    1994-01-01

    High temperature superconductors (HTS) hold the promise for applications in magnetic levitation bearings, vibration damping, and torque coupling. Traditional magnetic suspension systems require active feedback and vibration controls in which power consumption and low frequency vibration are among the major engineering concerns. HTS materials have been demonstrated to be an enabling approach towards such problems due to their flux trapping properties. In our laboratory at TCSUH, we have been conducting a series of experiments to explore various mechanical applications using HTS. We have constructed a 30 lb. model flywheel levitated by a hybrid superconducting magnetic bearing (HSMB). We are also developing a levitated and vibration-dampled platform for high precision instrumentation. These applications would be ideal for space usages where ambient temperature is adequate for HTS to operate properly under greatly reduced cryogenic requirements. We will give a general overview of these potential applications and discuss the operating principles of the HTS devices we have developed.

  13. Simulated Data for High Temperature Composite Design

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.; Abumeri, Galib H.

    2006-01-01

    The paper describes an effective formal method that can be used to simulate design properties for composites that is inclusive of all the effects that influence those properties. This effective simulation method is integrated computer codes that include composite micromechanics, composite macromechanics, laminate theory, structural analysis, and multi-factor interaction model. Demonstration of the method includes sample examples for static, thermal, and fracture reliability for a unidirectional metal matrix composite as well as rupture strength and fatigue strength for a high temperature super alloy. Typical results obtained for a unidirectional composite show that the thermal properties are more sensitive to internal local damage, the longitudinal properties degrade slowly with temperature, the transverse and shear properties degrade rapidly with temperature as do rupture strength and fatigue strength for super alloys.

  14. Polaron models of high-temperature superconductivity

    NASA Astrophysics Data System (ADS)

    Mott, N. F.

    1993-01-01

    A review is given of theories of high-temperature superconductors in which the current is carried by bipolarons, which form a condensed Bose gas below Tc and a non-degenerate gas above it. Such theories were first proposed by Schafroth, Alexandrov, Ranninger and de Jongh; the present author has, for the copper oxide materials, proposed spin bipolarons. Experimental work has, however, shown no magnetic moments in the superconducting and “spin glass” ranges of composition; a modification of the spin bipolaron model is proposed to take account of these observations. Other aspects of the model are discussed, particularly heat conduction and the effect of disorder. A comparison is made with the cubic bismuth materials.

  15. Graphite thermal expansion reference for high temperature

    NASA Technical Reports Server (NTRS)

    Gaal, P. S.

    1974-01-01

    The design requirements of the aerospace and high-temperature nuclear reactor industries necessitate reliable thermal expansion data for graphite and other carbonaceous materials. The feasibility of an acceptable reference for calibration of expansion measuring systems that operate in carbon-rich atmospheres at temperatures ranging to 2500 C is the prime subject of this work. Present-day graphite technology provides acceptable materials for stable, reproducible references, as reflected by some of the candidate materials. The repeatability for a single specimen in a given expansion measuring system was found to be plus or minus 1%, while the combined results of several tests made on a number of samples fell within a plus or minus 2.5% band.

  16. High temperature application of retrievable MWD systems

    SciTech Connect

    Coe, R.; Saito, S.

    1995-12-31

    MWD systems are currently used to monitor the direction of wellbores. MWD systems with higher temperature capabilities are required to meet the needs of deep and geothermal drilling. A technique has been developed for geothermal drilling that allows a fully retrievable MWD system to be used in wells with formation temperatures in excess of 350{degrees}C. This operational technique involves use of the MWD system in combination with operational procedures adapted to cope with the need for continuous directional control while drilling. Descriptions of the drilling environment are given in areas of Japan where high temperature drilling is performed. Possible future requirements are reviewed. The MWD system is described giving current technical specifications and capabilities. The operational method for utilizing the MWD is detailed. A summary of successful applications is discussed and specific case studies given. The efficiency of using the technique is reviewed.

  17. Optically transparent high temperature shape memory polymers.

    PubMed

    Xiao, Xinli; Qiu, Xueying; Kong, Deyan; Zhang, Wenbo; Liu, Yanju; Leng, Jinsong

    2016-03-21

    Optically transparent shape memory polymers (SMPs) have potential in advanced optoelectronic and other common shape memory applications, and here optically transparent shape memory polyimide is reported for the first time. The polyimide possesses a glass transition temperature (Tg) of 171 °C, higher than the Tg of other transparent SMPs reported, and the influence of molecular structure on Tg is discussed. The 120 μm thick polyimide film exhibits transmittance higher than 81% in 450-800 nm, and the possible mechanism of its high transparency is analyzed, which will benefit further research on other transparent high temperature SMPs. The transparent polyimide showed excellent thermomechanical properties and shape memory performances, and retained high optical transparency after many shape memory cycles. PMID:26686222

  18. High Temperature Superconductivity and Cold Fusion

    NASA Astrophysics Data System (ADS)

    Rabinowitz, Mario

    There are numerous historical and scientific parallels between high temperature superconductivity (HTSC) and the newly emerging field of cold fusion (CF). Just as the charge carrier effective mass plays an important role in SC, the deuteron effective mass may play a vital role in CF. A new theory including effects of proximity, electron shielding, and decreased effective mass of the fusing nuclei can account for the reported CF results. A quantum-gas model that covers the range from low temperature to superhigh temperature SC indicates an increased Tc with reduced dimensionality. A reduced dimensionality effect may also enhance CF. A relation is shown between CF and the significant cluster-impact fusion experiments.

  19. Spin Hall magnetoresistance at high temperatures

    SciTech Connect

    Uchida, Ken-ichi; Qiu, Zhiyong; Kikkawa, Takashi; Iguchi, Ryo; Saitoh, Eiji

    2015-02-02

    The temperature dependence of spin Hall magnetoresistance (SMR) in Pt/Y{sub 3}Fe{sub 5}O{sub 12} (YIG) bilayer films has been investigated in a high temperature range from room temperature to near the Curie temperature of YIG. The experimental results show that the magnitude of the magnetoresistance ratio induced by the SMR monotonically decreases with increasing the temperature and almost disappears near the Curie temperature. We found that, near the Curie temperature, the temperature dependence of the SMR in the Pt/YIG film is steeper than that of a magnetization curve of the YIG; the critical exponent of the magnetoresistance ratio is estimated to be 0.9. This critical behavior of the SMR is attributed mainly to the temperature dependence of the spin-mixing conductance at the Pt/YIG interface.

  20. High temperature superconductor materials and applications

    NASA Technical Reports Server (NTRS)

    Doane, George B., III. (Editor); Banks, Curtis; Golben, John

    1991-01-01

    One of the areas concerned itself with the investigation of the phenomena involved in formulating and making in the laboratory new and better superconductor material with enhanced values of critical current and temperature. Of special interest were the chemistry, physical processes, and environment required to attain these enhanced desirable characteristics. The other area concerned itself with producing high temperature superconducting thin films by pulsed laser deposition techniques. Such films are potentially very useful in the detection of very low power signals. To perform this research high vacuum is required. In the course of this effort, older vacuum chambers were maintained and used. In addition, a new facility is being brought on line. This latter activity has been replete with the usual problems of bringing a new facility into service. Some of the problems are covered in the main body of this report.

  1. High-Temperature Solar Cell Development

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Raffaelle, Ryne P.; Merritt, Danielle

    2004-01-01

    The vast majority of satellites and near-earth probes developed to date have relied upon photovoltaic power generation. If future missions to probe environments close to the sun will be able to use photovoltaic power, solar cells that can function at high temperatures, under high light intensity, and high radiation conditions must be developed. For example, the equilibrium temperature of a Mercury surface station will be about 450 C, and the temperature of solar arrays on the proposed "Solar Probe" mission will extend to temperatures as high as 2000 C (although it is likely that the craft will operate on stored power rather than solar energy during the closest approach to the sun). Advanced thermal design principles, such as replacing some of the solar array area with reflectors, off-pointing, and designing the cells to reflect rather than absorb light out of the band of peak response, can reduce these operating temperature somewhat. Nevertheless, it is desirable to develop approaches to high-temperature solar cell design that can operate under temperature extremes far greater than today's cells. Solar cells made from wide bandgap (WBG) compound semiconductors are an obvious choice for such an application. In order to aid in the experimental development of such solar cells, we have initiated a program studying the theoretical and experimental photovoltaic performance of wide bandgap materials. In particular, we have been investigating the use of GaP, SiC, and GaN materials for space solar cells. We will present theoretical results on the limitations on current cell technologies and the photovoltaic performance of these wide-bandgap solar cells in a variety of space conditions. We will also give an overview of some of NASA's cell developmental efforts in this area and discuss possible future mission applications.

  2. High Temperature VARTM of Phenylethynyl Terminated Imides

    NASA Technical Reports Server (NTRS)

    Cano, Roberto J.; Britton, Sean M.; Jensen, Brian J.; Connell, John W.; Herring, Helen M.; Linberry, Quentin J.; Ghose, Sayata; Watson, Kent A.

    2009-01-01

    Fabrication of composite structures using vacuum assisted resin transfer molding (VARTM) is generally more affordable than conventional autoclave techniques. Recent efforts have focused on adapting VARTM for the fabrication of high temperature composites. Due to their low melt viscosity and long melt stability, certain phenylethynyl terminated imides (PETI) can be processed into composites using high temperature VARTM (HT-VARTM). However, one of the disadvantages of the current HT-VARTM resin systems has been the high porosity of the resultant composites. For aerospace applications, the desired void fraction of less than 2% has not yet been achieved. In the current study, two PETI resins, LaRC PETI-330 and LaRC PETI-8 have been used to make test specimens using HT-VARTM. The resins were infused into ten layers of IM7-6K carbon fiber 5-harness satin fabric at 260 C or 280 C and cured at 371 C. Initial runs yielded composites with high void content, typically greater than 7% by weight. A thermogravimetric-mass spectroscopic study was conducted to determine the source of volatiles leading to high porosity. It was determined that under the thermal cycle used for laminate fabrication, the phenylethynyl endcap was undergoing degradation leading to volatile evolution. By modifying the thermal cycle used in laminate fabrication, the void content was reduced significantly (typically approximately 3%). Densities of the composites were determined using a density gradient column and the glass transition temperatures of the cured composites were measured by dynamic mechanical analysis. Photomicrographs of the panels were taken and void contents were determined by acid digestion. The results of this work are presented herein.

  3. An Ultra High Temperature Positive Photoresist

    NASA Astrophysics Data System (ADS)

    Grunwald, John; Turner, Edwin J.; Spencer, Allen C.; Sawoska, David A.; Ben-Shushan, Giyora

    1985-04-01

    This paper discusses the functional performance features of a new positive photoresist designated as ULTRAMAC' PR78T that can be subjected to temperatures up to 220°C. without any changes in the critical dimensions (CD's). No deep UV stabilization, intermediate post bakes, or other stabilization techniques are required to achieve high temperature thermal stability (220°C.). This high temperature positive photoresist is based on a diazo-coupled alkali soluble resin. The resolution and photospeed of this resist, ULTRAMAC' PR78T, are shown to be in the order of 1 micron using a 1.5 microns resist film thickness at 44 mJ/cm2. This resist also has submicron capabilities using step-and-repeat exposure equipment (10:1) utilizing monochromatic 436 nanometer light. ULTRAMAC' PR78T resist shows optimum sensitivity in the 300 - 500 nanometer UV spectral range. In contact or projection exposure equipment, resolution in the order of 1 micron can be achieved using a 1 micron resist film with exposure energies of about 35 mJ/cm2. For steppers using monochromatic light at 436 nanometers, typical exposure energies are in the order of 160 to 180 mJ/cm2, using either metal-ion-free or buffered metal based developers. Contrast (gamma) curves are shown for both metal-ion-free developer, ULTRAMAC' MF72A, and buffered metal containing developer, ULTRAMAC" D71A. High current ion implant data is also presented, showing no resist degradation. Anisotropic plasma/RIE etching selectivity data is also shown on SiO2 and aluminum alloy substrates.

  4. High Temperature VARTM of Phenylethynyl Terminated Imides

    NASA Technical Reports Server (NTRS)

    Ghose, Sayata; Cano, Roberto J.; Watson, Kent A.; Britton, Sean M.; Jensen, Brian J.; Connell, John W.; Herring, Helen M.; Linberry, Quentin J.

    2009-01-01

    Depending on the part type and quantity, fabrication of composite structures using vacuum assisted resin transfer molding (VARTM) can be more affordable than conventional autoclave techniques. Recent efforts have focused on adapting VARTM for the fabrication of high temperature composites. Due to their low melt viscosity and long melt stability, certain phenylethynyl terminated imides (PETI) can be processed into composites using high temperature VARTM (HT-VARTM). However, one of the disadvantages of the current HT-VARTM resin systems has been the high porosity of the resultant composites. For aerospace applications, the desired void fraction of less than 2% has not yet been achieved. In the current study, two PETI resins, LaRC PETI-330 and LaRC PETI-8 have been used to make test specimens using HT-VARTM. The resins were infused into ten layers of IM7-6K carbon fiber 5-harness satin fabric at 260 C or 280 C and cured at temperature up to 371 C. Initial runs yielded composites with high void content, typically greater than 7% by weight. A thermogravimetric-mass spectroscopic study was conducted to determine the source of volatiles leading to high porosity. It was determined that under the thermal cycle used for laminate fabrication, the phenylethynyl endcap was undergoing degradation leading to volatile evolution. This finding was unexpected as high quality composite laminates have been fabricated under higher pressures using these resin systems. The amount of weight loss experienced during the thermal cycle was only about 1% by weight, but this leads to a significant amount of volatiles in a closed system. By modifying the thermal cycle used in laminate fabrication, the void content was significantly reduced (typically 3% or less). The results of this work are presented herein.

  5. New chemical reactions in methane at high temperatures and pressures

    SciTech Connect

    Culler, T.S.; Schiferl, D. )

    1993-01-21

    The authors have used a Merrill-Bassett diamond anvil cell and Raman spectroscopy to study methane at high pressures (up to 13 GPa) and high temperatures (up to 912 K). At 2.5-5.0 GPa and 912 K, methane photoreacts with the laser light used for Raman spectroscopy and forms a graphitelike soot compound. At room temperature and pressure the Raman spectrum of the new material has an intense peak with a frequency of 1597 cm[sup [minus]1]. At higher pressures and temperatures (10-13 GPa and 948 K) a sample of [sup 13]CD[sub 4] methane photoreacted with the laser light and formed a hard, clear, solid film. At 0.34 GPa and 300 K, this film had Raman peaks at 541 and 1605 cm[sup [minus]1]. The 541-cm[sup [minus]1] peak may correspond to the 550-cm[sup [minus]1] peak found in some diamondlike carbon (DLC) films formed by chemical vapor deposition (CVD), but the 1605-cm[sup [minus]1] peak does not appear to have any such counterpart. Other possible Raman peaks were masked by interference from the diamond anvils. Thus, while the hard, clear film has some similarities to CVD DLC films, some important differences and questions remain. 35 refs., 5 figs.

  6. High Temperature Integrated Thermoelectric Ststem and Materials

    SciTech Connect

    Mike S. H. Chu

    2011-06-06

    The final goal of this project is to produce, by the end of Phase II, an all ceramic high temperature thermoelectric module. Such a module design integrates oxide ceramic n-type, oxide ceramic p-type materials as thermoelectric legs and oxide ceramic conductive material as metalizing connection between n-type and p-type legs. The benefits of this all ceramic module are that it can function at higher temperatures (> 700 C), it is mechanically and functionally more reliable and it can be scaled up to production at lower cost. With this all ceramic module, millions of dollars in savings or in new opportunities recovering waste heat from high temperature processes could be made available. A very attractive application will be to convert exhaust heat from a vehicle to reusable electric energy by a thermoelectric generator (TEG). Phase I activities were focused on evaluating potential n-type and p-type oxide compositions as the thermoelectric legs. More than 40 oxide ceramic powder compositions were made and studied in the laboratory. The compositions were divided into 6 groups representing different material systems. Basic ceramic properties and thermoelectric properties of discs sintered from these powders were measured. Powders with different particles sizes were made to evaluate the effects of particle size reduction on thermoelectric properties. Several powders were submitted to a leading thermoelectric company for complete thermoelectric evaluation. Initial evaluation showed that when samples were sintered by conventional method, they had reasonable values of Seebeck coefficient but very low values of electrical conductivity. Therefore, their power factors (PF) and figure of merits (ZT) were too low to be useful for high temperature thermoelectric applications. An unconventional sintering method, Spark Plasma Sintering (SPS) was determined to produce better thermoelectric properties. Particle size reduction of powders also was found to have some positive benefits

  7. High Pressure Study on High Temperature Superconductors

    NASA Astrophysics Data System (ADS)

    Lin, Jauyn Grace

    In spite of the progress on the understanding of high-temperature superconductivity (HTS), there is still not sufficient evidence to differentiate one theoretical model from the others. In an attempt to relate the crystal structures of high-temperature superconductors (HTS's) to the mechanism of HTS, we have adopted a chemico-physical approach by examining the pressure-effect on the superconducting and transport properties of superconducting compound systems. Without exception, all compounds exhibiting superconductivity above 77 K, the boiling point of liquid nitrogen, are anisotropic structures consisting of layers of CuO_2 , metal element (R's; where R is R being Ca, Y or rare-earth element) and metal-oxide (MO's; where M is Ca, Ba, Sr, Cu, Hg, Tl, Bi or Pb). We have investigated under pressure the electrical and superconducting properties of four highly related systems with different R's, different numbers of MO layers, different numbers of CuO _2 layers and various anion dopings. The specific systems studied were: RBa_2Cu _3O_7 (R = Y, Yb, Tm, Ho, Dy, Gd, Sm and Nd), R_{1 -x}Pr_{x}Ba _2Cu_3O _7 (R = Yb and Dy), Y_2Ba _4Cu_{5 + m} O_{13 + m} (m = 1, 2 and 3), and Tl_2Ba _2Ca_{L-1}Cu _{2L-1}O_ {4 + 2L-delta} (L= 1,2 and 3, and 0 <= delta <= 0.1). We found that: (1) in R-123, R affects T _{c} due to its chemical pressure which, in turn, can lead to a modification in the electronic structure of HTS's, in contrast to the general belief that R is isolated from the superconducting CuO_2 layers and hence has no influence on T _{c}; (2) the absence of superconductivity in PrBa_2Cu_3O _7 may be due to the low carrier concentration and hole-localization, in contrast to the suggestion of pair-breaking; (3) there may exist a common optimal T_{c} for all members of the homologous series Y_2Ba _4Cu_{5 + m} O_{13 + m}, raising the possibility of a similar situation in other compound families; and (4) We have observed a universal T _{c}-behavior for HTS's. We believe that these

  8. High-Temperature Shape Memory Polymers

    NASA Technical Reports Server (NTRS)

    Yoonessi, Mitra; Weiss, Robert A.

    2012-01-01

    physical conformation changes when exposed to an external stimulus, such as a change in temperature. Such materials have a permanent shape, but can be reshaped above a critical temperature and fixed into a temporary shape when cooled under stress to below the critical temperature. When reheated above the critical temperature (Tc, also sometimes called the triggering or switching temperature), the materials revert to the permanent shape. The current innovation involves a chemically treated (sulfonated, carboxylated, phosphonated, or other polar function group), high-temperature, semicrystalline thermoplastic poly(ether ether ketone) (Tg .140 C, Tm = 340 C) mix containing organometallic complexes (Zn++, Li+, or other metal, ammonium, or phosphonium salts), or high-temperature ionic liquids (e.g. hexafluorosilicate salt with 1-propyl-3- methyl imidazolium, Tm = 210 C) to form a network where dipolar or ionic interactions between the polymer and the low-molecular-weight or inorganic compound forms a complex that provides a physical crosslink. Hereafter, these compounds will be referred to as "additives". The polymer is semicrystalline, and the high-melt-point crystals provide a temporary crosslink that acts as a permanent crosslink just so long as the melting temperature is not exceeded. In this example case, the melting point is .340 C, and the shape memory critical temperature is between 150 and 250 C. PEEK is an engineering thermoplastic with a high Young fs modulus, nominally 3.6 GPa. An important aspect of the invention is the control of the PEEK functionalization (in this example, the sulfonation degree), and the thermal properties (i.e. melting point) of the additive, which determines the switching temperature. Because the compound is thermoplastic, it can be formed into the "permanent" shape by conventional plastics processing operations. In addition, the compound may be covalently cross - linked after forming the permanent shape by S-PEEK by applying ionizing

  9. Electrochemical high-temperature gas sensors

    NASA Astrophysics Data System (ADS)

    Saruhan, B.; Stranzenbach, M.; Yüce, A.; Gönüllü, Y.

    2012-06-01

    Combustion produced common air pollutant, NOx associates with greenhouse effects. Its high temperature detection is essential for protection of nature. Component-integration capable high-temperature sensors enable the control of combustion products. The requirements are quantitative detection of total NOx and high selectivity at temperatures above 500°C. This study reports various approaches to detect NO and NO2 selectively under lean and humid conditions at temperatures from 300°C to 800°C. All tested electrochemical sensors were fabricated in planar design to enable componentintegration. We suggest first an impedance-metric gas sensor for total NOx-detection consisting of NiO- or NiCr2O4-SE and PYSZ-electrolyte. The electrolyte-layer is about 200μm thickness and constructed of quasi-single crystalline columns. The sensing-electrode (SE) is magnetron sputtered thin-layers of NiO or NiCr2O4. Sensor sensitivity for detection of total NOx has been measured by applying impedance analysis. The cross-sensitivity to other emission gases such as CO, CO2, CH4 and oxygen (5 vol.%) has been determined under 0-1000ppm NO. Sensor maintains its high sensitivity at temperatures up to 550°C and 600°C, depending on the sensing-electrode. NiO-SE yields better selectivity to NO in the presence of oxygen and have shorter response times comparing to NiCr2O4-SE. For higher temperature NO2-sensing capability, a resistive DC-sensor having Al-doped TiO2-sensing layers has been employed. Sensor-sensitivity towards NO2 and cross-sensitivity to CO has been determined in the presence of H2O at temperatures 600°C and 800°C. NO2 concentrations varying from 25 to 100ppm and CO concentrations from 25 to 75ppm can be detected. By nano-tubular structuring of TiO2, NO2 sensitivity of the sensor was increased.

  10. Fiber Bragg Grating Filter High Temperature Sensors

    NASA Technical Reports Server (NTRS)

    Lyons, Donald R.; Brass, Eric D.; Pencil, Eric (Technical Monitor)

    2001-01-01

    We present a scaled-down method for determining high temperatures using fiber-based Bragg gratings. Bragg gratings are distributed along the length of the optical fiber, and have high reflectivities whenever the optical wavelength is twice the grating spacing. These spatially distinct Bragg regions (located in the core of a fiber) are sensitive to local temperature changes. Since these fibers are silica-based they are easily affected by localized changes in temperature, which results in changes to both the grating spacing and the wavelength reflectivity. We exploit the shift in wavelength reflectivity to measure the change in the local temperature. Note that the Bragg region (sensing area) is some distance away from where the temperature is being measured. This is done so that we can measure temperatures that are much higher than the damage threshold of the fiber. We do this by affixing the fiber with the Bragg sensor to a material with a well-known coefficient of thermal expansion, and model the heat gradient from the region of interest to the actual sensor. The research described in this paper will culminate in a working device as well as be the second portion of a publication pending submission to Optics Letters.

  11. High Temperature Interactions of Antimony with Nickel

    SciTech Connect

    Marina, Olga A.; Pederson, Larry R.

    2012-07-01

    In this chapter, the surface and bulk interactions of antimony with the Ni-based anodes in solid oxide fuel cells (SOFC) will be discussed. High fuel flexibility is a significant advantage of SOFCs, allowing the direct use of fossil and bio fuels without a hydrogen separation unit. Synthesis gas derived from coal and biomass consists of a mixture of hydrogen, carbon monoxide, carbon dioxide, and steam, but finite amounts of tars and trace impurities such as S, Se, P, As, Sb, Cd, Pb, Cl, etc, are also always present. While synthesis gas is commonly treated with a series of chemical processes and scrubbers to remove the impurities, complete purification is not economical. Antimony is widely distributed in coals. During coal gasification antimony is volatilized, such that contact with the SOFC anodes and other SOFC parts, e.g., interconnect, current collecting wires, fuel gas supplying tubing, is most likely. This chapter addresses the following topics: high temperature Ni - Sb interactions; alteration phase, Ni3Sb, Ni5Sb2, NiSb, formation; thermochemical modeling; impact of Sb on the electrocatalytic activity of Ni toward the fuel oxidation and the presence of other impurities (sulfur, in particular); converted anode structural instability during long-term SOFC operation; comparison with nickel heterogeneous catalysts.

  12. The moon as a high temperature condensate.

    NASA Technical Reports Server (NTRS)

    Anderson, D. L.

    1973-01-01

    The accretion during condensation mechanism, if it occurs during the early over-luminous stage of the sun, can explain the differences in composition of the terrestrial planets and the moon. An important factor is the variation of pressure and temperature with distance from the sun, and in the case of the moon and captured satellites of other planets, with distance from the median plane. Current estimates of the temperature and pressure in the solar nebula suggest that condensation will not be complete in the vicinity of the terrestrial planets, and that depending on location, iron, magnesium silicates and the volatiles will be at least partially held in the gaseous phase and subject to separation from the dust by solar wind and magnetic effects associated with the transfer of angular momentum just before the sun joins the Main Sequence. Many of the properties of the moon, including the 'enrichment' in Ca, Al, Ti, U, Th, Ba, Sr and the REE and the 'depletion' in Fe, Rb, K, Na and other volatiles can be understood if the moon represents a high temperature condensate from the solar nebula.

  13. High Temperature Aerogels for Thermal Protection Systems

    NASA Technical Reports Server (NTRS)

    Hurwitz, Frances I.; Mbah, Godfrey C.

    2008-01-01

    High temperature aerogels in the Al2O3-SiO2 system are being investigated as possible constituents for lightweight integrated thermal protection system (TPS) designs for use in supersonic and hypersonic applications. Gels are synthesized from ethoxysilanes and AlCl3.6H2O, using an epoxide catalyst. The influence of Al:Si ratio, solvent, water to metal and water to alcohol ratios on aerogel composition, morphology, surface area, and pore size distribution were examined, and phase transformation on heat treatment characterized. Aerogels have been fabricated which maintain porous, fractal structures after brief exposures to 1000 C. Incorporation of nanofibers, infiltration of aerogels into SiC foams, use of polymers for crosslinking the aerogels, or combinations of these, offer potential for toughening and integration of TPS with composite structure. Woven fabric composites having Al2O3-SiO2 aerogels as a matrix also have been fabricated. Continuing work is focused on reduction in shrinkage and optimization of thermal and physical properties.

  14. Urania vapor composition at very high temperatures

    SciTech Connect

    Pflieger, Rachel; Colle, Jean-Yves; Iosilevskiy, Igor; Sheindlin, Michael

    2011-02-01

    Due to the chemically unstable nature of uranium dioxide its vapor composition at very high temperatures is, presently, not sufficiently studied though more experimental knowledge is needed for risk assessment of nuclear reactors. We used laser vaporization coupled to mass spectrometry of the produced vapor to study urania vapor composition at temperatures in the vicinity of its melting point and higher. The very good agreement between measured melting and freezing temperatures and between partial pressures measured on the temperature increase and decrease indicated that the change in stoichiometry during laser heating was very limited. The evolutions with temperature (in the range 2800-3400 K) of the partial pressures of the main vapor species (UO{sub 2}, UO{sub 3}, and UO{sub 2}{sup +}) were compared with theoretically predicted evolutions for equilibrium noncongruent gas-liquid and gas-solid phase coexistences and showed very good agreement. The measured main relative partial pressure ratios around 3300 K all agree with calculated values for total equilibrium between condensed and vapor phases. It is the first time the three main partial pressure ratios above stoichiometric liquid urania have been measured at the same temperature under conditions close to equilibrium noncongruent gas-liquid phase coexistence.

  15. High temperature calorimetry of sulfide systems

    NASA Astrophysics Data System (ADS)

    Cemič, L.; Kleppa, O. J.

    1987-01-01

    Enthalpies of solution of synthetic pentlandite Fe4.5Ni4.5S8, natural violarite (Fe0.2941Ni0.7059)3S4 from Vermillion mine, Sudbury, Ontario, synthetic pyrrhotite, FeS, synthetic high temperature NiS, synthetic vaesite, NiS2, synthetic pyrite, FeS2, Ni and Fe have been measured in a Ni0.6S0.4 melt at 1,100 K. Using these data and the standard enthalpies of formation of binary sulfides, given in literature, standard enthalpies of formation of pentlandite and violarite were calculated. The following values are reported: Δ H {f/o, Pent}=-837.37±14.59 kJ mol-1 and Δ H {f/o, Viol}=-378.02±11.81 kJ mol-1. While there are no thermo-chemical data for pentlandite with which our new value can be compared, an equilibrium investigation of stoichiometric violarite by Craig (1971) gives a significantly less negative enthalpy of formation. It is suggested that the difference may be due to the higher degree of order in the natural sample.

  16. Ceramic high temperature receiver design and tests

    NASA Technical Reports Server (NTRS)

    Davis, S. B.

    1982-01-01

    The High Temperature Solar Thermal Receiver, which was tested a Edwards AFB, CA during the winter of 1980-1981, evolved from technologies developed over a five year period of work. This receiver was tested at the Army Solar Furnace at White Sands, NM in 1976. The receiver, was tested successfully at 1768 deg F and showed thermal efficiencies of 85%. The results were sufficiently promising to lead ERDA to fund our development and test of a 250 kW receiver to measure the efficiency of an open cavity receiver atop a central tower of a heliostat field. This receiver was required to be design scalable to 10, 50, and 100 MW-electric sizes to show applicability to central power tower receivers. That receiver employed rectagular silicon carbide panels and vertical stanchions to achieve scalability. The construction was shown to be fully scalable; and the receiver was operated at temperatures up to 2000 deg F to achieve the performance goals of the experiment during tests at the GIT advanced components test facility during the fall of 1978.

  17. Improved Seals for High Temperature Airframe Applications

    NASA Technical Reports Server (NTRS)

    DeMange, Jeffrey J.; Dunlap, Patrick H.; Steinetz, Bruce M.

    2006-01-01

    Current thermal barrier seals, such as those used on the Space Shuttle, are insufficient to fully meet the demands of future hypersonic vehicles and reentry spacecraft. Previous investigations have demonstrated limited usage temperatures, as evidenced by a decreased ability to maintain sealing effectiveness at high temperatures (i.e., inadequate resiliency). In order to improve resiliency at elevated temperatures, Rene 41 (Allvac) was substituted for Inconel X-750 (Special Metals Corp.) as the spring tube material in the existing seal design. A seal construction incorporating the Rene 41 spring tube was fabricated and tested against the baseline Inconel X-750 spring tube seal. Although resiliency improvements were not as dramatic as in previous tests with the spring tubes alone, seals incorporating the Rene 41 spring tube exhibited an average 20 percent resiliency enhancement up to 1750 F when compared to seals containing the Inconel spring tube. In addition, the seals with the Rene 41 spring tubes showed less reduction in resiliency as temperatures increased above 1200 F. Results also indicated the Saffil (Saffil Ltd.) insulation in the core of the seal contributed more to resiliency than previously thought. Leakage data did not demonstrate an improvement with the seal containing the Rene 41 spring tube. However, based upon resiliency results, one could reasonably expect the Rene 41 version of the seal to track gap openings over a wider range. Therefore it would exhibit lower leakage than the Inconel X-750 version as the seal gap opens during a typical mission.

  18. Heat Transfer in High Temperature Multilayer Insulation

    NASA Technical Reports Server (NTRS)

    Daryabeigi, Kamran; Miller, Steve D.; Cunnington, George R.

    2007-01-01

    High temperature multilayer insulations have been investigated as an effective component of thermal-protection systems for atmospheric re-entry of reusable launch vehicles. Heat transfer in multilayer insulations consisting of thin, gold-coated, ceramic reflective foils and Saffil(TradeMark) fibrous insulation spacers was studied both numerically and experimentally. A finite volume numerical thermal model using combined conduction (gaseous and solid) and radiation in porous media was developed. A two-flux model with anisotropic scattering was used for radiation heat transfer in the fibrous insulation spacers between the reflective foils. The thermal model was validated by comparison with effective thermal conductivity measurements in an apparatus based on ASTM standard C201. Measurements were performed at environmental pressures in the range from 1x10(exp -4) to 760 torr over the temperature range from 300 to 1300 K. Four multilayer samples with nominal densities of 48 kg/cu m were tested. The first sample was 13.3 mm thick and had four evenly spaced reflective foils. The other three samples were 26.6 mm thick and utilized either one, two, or four reflective foils, located near the hot boundary with nominal foil spacing of 1.7 mm. The validated thermal model was then used to study relevant design parameters, such as reflective foil spacing and location in the stack-up and coating of one or both sides of foils.

  19. Chemical stability of high-temperature superconductors

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.

    1992-01-01

    A review of the available studies on the chemical stability of the high temperature superconductors (HTS) in various environments was made. The La(1.8)Ba(0.2)CuO4 HTS is unstable in the presence of H2O, CO2, and CO. The YBa2Cu3O(7-x) superconductor is highly susceptible to degradation in different environments, especially water. The La(2-x)Ba(x)CuO4 and Bi-Sr-Ca-Cu-O HTS are relatively less reactive than the YBa2Cu3O(7-x). Processing of YBa2Cu3O(7-x) HTS in purified oxygen, rather than in air, using high purity noncarbon containing starting materials is recommended. Exposure of this HTS to the ambient atmosphere should also be avoided at all stages during processing and storage. Devices and components made out of these oxide superconductors would have to be protected with an impermeable coating of a polymer, glass, or metal to avoid deterioration during use.

  20. Light Scattering on the High Temperature Superconductors

    NASA Astrophysics Data System (ADS)

    Slakey, Francis

    The high temperature superconductors have been examined by the technique of Raman scattering in several limits: the insulating phase, the normal and superconducting state of the superconducting phase, and an optically induced metastable phase. In all cases, the analysis and proposed phenomenological models involved either an examination of the inelastic background scattering or the phonon excitation spectrum. Specifically, the character, temperature dependence, critical temperature dependence and the copper-oxygen covalency dependence of the inelastic background scattering has been studied in all three phases. Analysis of the superconducting phase reveals a marginal Fermi-liquid like character of the electronic polarizability, and a decidedly non-traditional shift of the scattering intensity of the electronic excitations at low temperature. On removing oxygen, the system passes through a metal-insulator transition and the inelastic background becomes dominantly magnetic in origin. Examinations of the 'allowed' Raman active phonons in the superconducting phase expose a strong coupling of two modes to the background electronic excitation spectrum, and a dramatic renormalization of these modes below T _{rm c}. Further, two sharply resonant Raman 'forbidden' modes can be bleached out of the spectrum at low temperature with a sufficiently high laser dosage. A transition from this optically induced metastable state to the normal state occurs on warming the crystal back to room temperature. On reducing the oxygen concentration, the coupling strength of the two asymmetric phonons diminishes rapidly, the renormalization effects vanish, and the compound no longer exhibits metastability.

  1. High Temperature Wear of Advanced Ceramics

    NASA Technical Reports Server (NTRS)

    DellaCorte, C.

    2005-01-01

    It was initially hypothesized that advanced ceramics would exhibit favorable high te- friction and wear properties because of their high hot hardness and low achievable surface roughness welding observed in metals does not occur in ceramics. More recent tribological studies of many nitride, carbide, oxide and composite ceramics, however, have revealed that ceramics often exhibit high friction and wear in non-lubricated, high temperature sliding contacts. A summary is given to measure friction and wear factor coefficients for a variety of ceramics from self mated ceramic pin-on-disk tests at temperatures from 25 to up to 1200 C. Observed steady state friction coefficients range from about 0.5 to 1.0 or above. Wear factor coefficients are also very high and range from about to 10(exp -5) to 10(exp -2) cubic millimeters per N-m. By comparison, oil lubricated steel sliding results in friction coefficients of 0.1 or less and wear factors less than 10(exp -9) cubic millimeters per N-m.

  2. High temperature measurement of water vapor absorption

    NASA Technical Reports Server (NTRS)

    Keefer, Dennis; Lewis, J. W. L.; Eskridge, Richard

    1985-01-01

    An investigation was undertaken to measure the absorption coefficient, at a wavelength of 10.6 microns, for mixtures of water vapor and a diluent gas at high temperature and pressure. The experimental concept was to create the desired conditions of temperature and pressure in a laser absorption wave, similar to that which would be created in a laser propulsion system. A simplified numerical model was developed to predict the characteristics of the absorption wave and to estimate the laser intensity threshold for initiation. A non-intrusive method for temperature measurement utilizing optical laser-beam deflection (OLD) and optical spark breakdown produced by an excimer laser, was thoroughly investigated and found suitable for the non-equilibrium conditions expected in the wave. Experiments were performed to verify the temperature measurement technique, to screen possible materials for surface initiation of the laser absorption wave and to attempt to initiate an absorption wave using the 1.5 kW carbon dioxide laser. The OLD technique was proven for air and for argon, but spark breakdown could not be produced in helium. It was not possible to initiate a laser absorption wave in mixtures of water and helium or water and argon using the 1.5 kW laser, a result which was consistent with the model prediction.

  3. Synthesizing new, high-temperature superconductors

    NASA Astrophysics Data System (ADS)

    Weaver, Claire; Aronson, Meigan

    2015-03-01

    Currently, there is no accepted theory behind type-II, high-temperature superconductors, but there is a distinct relationship between anti-ferromagnetism and superconductivity. Our research focuses on synthesizing new superconducting materials by observing the link between atomic structure and magnetic moments of anti-ferromagnetic compounds and attempting to reproduce the molecular physics of these known materials in new compounds. Consider the square-planar arrangement of the transition metal Fe in the Fe-pnictide superconductors of the ZrCuSiAs ``11 11'' and the ThCr2Si2 ``122'' structure types. We believe that the physics behind this superconductor, where Fe has d6 valence electrons, contributes to the superconducting state, not the presence of Fe itself. For this reason, we are synthesizing materials containing neighboring transition metals, like Mn and Co, combined with other elements in similar crystal lattice arrangements, having ionization properties that hopefully impose d6 valence electrons on the transition metals. This project was supported in part by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists (WDTS) under the Science Undergraduate Laboratory Internships Program (SULI).

  4. Secondary calcium solid electrolyte high temperature battery

    SciTech Connect

    Sammells, A.F.; Schumacher, B.

    1986-01-01

    The authors report on recent work directed towards determining the viability of polycrystalline Ca/sup 2 +/ conducting ..beta..''-alumina solid electrolytes as the basis for a new type of high temperature battery. In this battery system the negative electrode consisted of a calcium-silicon alloy whose redox electro-chemistry was mediated to the calcium conducting solid electrolyte via the use of the molten salt eutectic CaCl/sub 2/ (51.4/sup M//0), CaI/sub 2/ (mp 550/sup 0/C). Both the molten salt and the calcium-alloy negative active material were separated from the positive active material via the Ca/sup 2 +/ conducting polycrystalline solid electrolyte. The positive electrode consisted of a solid-state matrix having a somewhat related crystallographic structure to Ca/sup 2 +/ ..beta..''-alumina, but where a significant fraction of the A1/sup 3 +/ sites located within this solid electrolyte's spinel block were replaced by immobile transition metal species. These species were available for participating in solid-state redox electrochemistry upon electrochemical cell cycling.

  5. Diffusion and plasticity at high temperature

    NASA Astrophysics Data System (ADS)

    Philibert, J.

    1991-06-01

    High temperature plastic deformation requires atomic migration whatever the mechanism of deformation. The constitutive equations contain a diffusion coefficient and the deformation rate follows an Arrhenius law. This paper will only discuss the case of viscous creep in order to elucidate the nature of the diffusion processes and the expression of the diffusion coefficient involved in alloys or compounds. La déformation plastique à haute température met en jeu des migrations atomiques, quel que soit le mécanisme de déformation. Les lois de comportement contiennent donc un coefficient de diffusion et la vitesse de déformation obéit à une loi d'Arrhenius. Dans cet article, qui ne conceme qu'un seul type de déformation, lefluage visqueux, on s'efforce de préciser la nature des processus de diffusion et du coefficient de diffusion mis en jeu dans le cas des alliages et des composés.

  6. Ceramic high temperature receiver design and tests

    SciTech Connect

    Davis, S.B.

    1982-07-01

    The High Temperature Solar Thermal Receiver, which was tested a Edwards AFB, CA during the winter of 1980-1981, evolved from technologies developed over a five year period of work. This receiver was tested at the Army Solar Furnace at White Sands, NM in 1976. The receiver, was tested successfully at 1768 deg F and showed thermal efficiencies of 85%. The results were sufficiently promising to lead ERDA to fund our development and test of a 250 kW receiver to measure the efficiency of an open cavity receiver atop a central tower of a heliostat field. This receiver was required to be design scalable to 10, 50, and 100 MW-electric sizes to show applicability to central power tower receivers. That receiver employed rectangular silicon carbide panels and vertical stanchions to achieve scalability. The construction was shown to be fully scalable, and the receiver was operated at temperatures up to 2000 deg F to achieve the performance goals of the experiment during tests at the GIT advanced components test facility during the fall of 1978.

  7. Perspectives on high temperature superconducting electronics

    NASA Technical Reports Server (NTRS)

    Venkatesan, T.

    1990-01-01

    The major challenges in making high temperature superconducting (HTSC) electronics viable are predominantly materials problems. Unlike their predecessors the metal oxide-based superconductors are integratable with other advanced technologies such as opto-electronics and micro-electronics. The materials problems to be addressed relate to the epitaxial growth of high quality films, highly oriented films on non-lattice matched substrates, heterostructures with atomically sharp interfaces of junctions and other novel devices, and the processing of these films with negligible deterioration of the superconducting properties. These issues are illustrated with results based on films prepared in-situ by a pulsed laser deposition process. Films with zero-transition temperatures of 90 K and critical current densities of 5 x 10(exp 6) A/sq cm at 77 K have been prepared by this technique. Ultra-thin films, less than 100 A show T(sub c) is greater than 80 K, supporting the idea of two-dimensional transport in these materials. By the use of appropriate buffer layers, films with T(sub c) of 87 K and J(sub c) of 6 x 10(exp 4) A/sq cm were fabricated on silicon substrates. Submicron structures with J(sub c) is greater than 2 x 10(exp 7) at 10 K were fabricated. Results on nonlinear switching elements, IR detectors, and microwave studies will be briefly summarized.

  8. Perspectives on high temperature superconducting electronics

    NASA Technical Reports Server (NTRS)

    Venkatesan, T.

    1991-01-01

    The major challenges in making high temperature superconducting (HTSC) electronics viable are predominantly materials problems. Unlike their predecessors, the metal oxide-based superconductors are integratable with other advanced technologies such as opto-electronics and micro-electronics. The materials problems to be addressed relate to the epitaxial growth of high quality films, highly oriented films on non-lattice matched substrates, heterostructures with atomically sharp interfaces of junctions and other novel devices, and the processing of these films with negligible deterioration of the superconducting properties. These issues are illustrated with results based on films prepared in-situ by a pulsed laser deposition process. Films with zero-transition temperatures of 90 K and critical current densities of 5 x 10(exp 6) A/sq cm at 77 K have been prepared by this technique. Ultra-thin films, less than 100 A show T(sub c) is greater than 80 K, supporting the idea of two-dimensional transport in these materials. By the use of appropriate buffer layers, films with T(sub c) of 87 K and J(sub c) of 6 x 10(exp 4) A/sq cm were fabricated on silicon substrates. Submicron structures with J(sub c) is greater than 2 x 10(exp 7) at 10 K were fabricated. Results on nonlinear switching elements, IR detectors, and microwave studies will be briefly summarized.

  9. High-temperature archeointensity measurements from Mesopotamia

    NASA Astrophysics Data System (ADS)

    Gallet, Yves; Le Goff, Maxime

    2006-01-01

    We present new archeointensity results obtained from 127 potsherds and baked brick fragments dated from the last four millennia BC which were collected from different Syrian archeological excavations. High temperature magnetization measurements were carried out using a laboratory-built triaxial vibrating sample magnetometer (Triaxe), and ancient field intensity determinations were derived from the experimental procedure described by Le Goff and Gallet [Le Goff and Gallet. Earth Planet. Sci. Lett. 229 (2004) 31-43]. As some of the studied samples were previously analyzed using the classical Thellier and Thellier [Thellier and Thellier . Ann. Geophys. 15 (1959) 285-376] method revised by Coe [Coe. J. Geophys. Res. 72 (1967) 3247-3262], a comparison of the results is made from the two methods. The differences both at the fragment and site levels are mostly within ± 5%, which strengthens the validity of the experimental procedure developed for the Triaxe. The new data help to better constrain the geomagnetic field intensity variations in Mesopotamia during archeological times, with the probable occurrence of an archeomagnetic jerk around 2800-2600 BC.

  10. High Temperature Borehole Televiewer software user manual

    SciTech Connect

    Duda, L.E.

    1989-11-01

    The High Temperature Borehole Televiewer is a downhole instrument which provides acoustic pictures of the borehole walls that are suitable for casing inspection and fracture detection in geothermal wells. The Geothermal Drilling Organization has funded the development of a commercial tool survivable to temperatures of 275{degree}C and pressures of 5000 psi. A real-time display on an IBM-compatible PC was included as part of the development effort. This report contains a User Manual which describes the operation of this software. The software is designed in a menu format allowing the user to change many of the parameters which control both the acquisition and the display of the Televiewer data. An internal data acquisition card digitizes the waveform from the tool at a rate of 100,000 samples per second. The data from the tool, both the range or arrival time and the amplitude of the return signal, are displayed in color on the CRT screen of the computer during the logging operation. This data may be stored on the hard disk for later display and analysis. The software incorporates many features which aid in the setup of the tool for proper operation. These features include displaying and storing the captured waveform data to check the voltage and time windows selected by the user. 17 refs., 28 figs., 15 tabs.

  11. High Temperature Materials for Chemical Propulsion Applications

    NASA Technical Reports Server (NTRS)

    Elam, Sandra; Hickman, Robert; O'Dell, Scott

    2007-01-01

    Radiation or passively cooled thrust chambers are used for a variety of chemical propulsion functions including apogee insertion, reaction control for launch vehicles, and primary propulsion for planetary spacecraft. The performance of these thrust chambers is limited by the operating temperature of available materials. Improved oxidation resistance and increased operating temperatures can be achieved with the use of thermal barrier coatings such as zirconium oxide (ZrO2) and hafnium oxide (HfO2). However, previous attempts to include these materials showed cracking and spalling of the oxide layer due to poor bonding. Current research at NASA's Marshall Space Flight Center (MSFC) has generated unique, high temperature material options for in-space thruster designs that are capable of up to 2500 C operating temperatures. The research is focused on fabrication technologies to form low cost Iridium,qF_.henium (Ir/Re) components with a ceramic hot wall created as an integral, functionally graded material (FGM). The goal of this effort is to further de?celop proven technologies for embedding a protective ceramic coating within the Ir/Re liner to form a robust functional gradient material. Current work includes the fabrication and testing of subscale samples to evaluate tensile, creep, thermal cyclic/oxidation, and thermophysical material properties. Larger test articles have also being fabricated and hot-fire tested to demonstrate the materials in prototype thrusters at 1O0 lbf thrust levels.

  12. Austenitic stainless steel for high temperature applications

    DOEpatents

    Johnson, Gerald D.; Powell, Roger W.

    1985-01-01

    This invention describes a composition for an austenitic stainless steel which has been found to exhibit improved high temperature stress rupture properties. The composition of this alloy is about (in wt. %): 12.5 to 14.5 Cr; 14.5 to 16.5 Ni; 1.5 to 2.5 Mo; 1.5 to 2.5 Mn; 0.1 to 0.4 Ti; 0.02 to 0.08 C; 0.5 to 1.0 Si; 0.01 maximum, N; 0.02 to 0.08 P; 0.002 to 0.008 B; 0.004-0.010 S; 0.02-0.05 Nb; 0.01-0.05 V; 0.005-0.02 Ta; 0.02-0.05 Al; 0.01-0.04 Cu; 0.02-0.05 Co; 0.03 maximum, As; 0.01 maximum, O; 0.01 maximum, Zr; and with the balance of the alloy being essentially iron. The carbon content of the alloy is adjusted such that wt. % Ti/(wt. % C+wt. % N) is between 4 and 6, and most preferably about 5. In addition the sum of the wt. % P+wt. % B+wt. % S is at least 0.03 wt. %. This alloy is believed to be particularly well suited for use as fast breeder reactor fuel element cladding.

  13. High temperature annealing of ion irradiated tungsten

    SciTech Connect

    Ferroni, Francesco; Yi, Xiaoou; Fitzgerald, Steven P.; Edmondson, Philip D.; Roberts, Steve G.

    2015-03-21

    In this study, transmission electron microscopy of high temperature annealing of pure tungsten irradiated by self-ions was conducted to elucidate microstructural and defect evolution in temperature ranges relevant to fusion reactor applications (500–1200°C). Bulk isochronal and isothermal annealing of ion irradiated pure tungsten (2 MeV W+ ions, 500°C, 1014 W+/cm2) with temperatures of 800, 950, 1100 and 1400°C, from 0.5 to 8 h, was followed by ex situ characterization of defect size, number density, Burgers vector and nature. Loops with diameters larger than 2–3 nm were considered for detailed analysis, among which all loops had View the MathML source and were predominantly of interstitial nature. In situ annealing experiments from 300 up to 1200°C were also carried out, including dynamic temperature ramp-ups. These confirmed an acceleration of loop loss above 900°C. At different temperatures within this range, dislocations exhibited behaviour such as initial isolated loop hopping followed by large-scale rearrangements into loop chains, coalescence and finally line–loop interactions and widespread absorption by free-surfaces at increasing temperatures. An activation energy for the annealing of dislocation length was obtained, finding Ea=1.34±0.2 eV for the 700–1100°C range.

  14. High temperature annealing of ion irradiated tungsten

    DOE PAGESBeta

    Ferroni, Francesco; Yi, Xiaoou; Arakawa, Kazuto; Fitzgerald, Steven P.; Edmondson, Philip D.; Roberts, Steve G.

    2015-03-21

    In this study, transmission electron microscopy of high temperature annealing of pure tungsten irradiated by self-ions was conducted to elucidate microstructural and defect evolution in temperature ranges relevant to fusion reactor applications (500–1200°C). Bulk isochronal and isothermal annealing of ion irradiated pure tungsten (2 MeV W+ ions, 500°C, 1014 W+/cm2) with temperatures of 800, 950, 1100 and 1400°C, from 0.5 to 8 h, was followed by ex situ characterization of defect size, number density, Burgers vector and nature. Loops with diameters larger than 2–3 nm were considered for detailed analysis, among which all loops had View the MathML source andmore » were predominantly of interstitial nature. In situ annealing experiments from 300 up to 1200°C were also carried out, including dynamic temperature ramp-ups. These confirmed an acceleration of loop loss above 900°C. At different temperatures within this range, dislocations exhibited behaviour such as initial isolated loop hopping followed by large-scale rearrangements into loop chains, coalescence and finally line–loop interactions and widespread absorption by free-surfaces at increasing temperatures. An activation energy for the annealing of dislocation length was obtained, finding Ea=1.34±0.2 eV for the 700–1100°C range.« less

  15. Very high temperature silicon on silicon pressure transducers

    NASA Technical Reports Server (NTRS)

    Kurtz, Anthony D.; Nunn, Timothy A.; Briggs, Stephen A.; Ned, Alexander

    1992-01-01

    A silicon on silicon pressure sensor has been developed for use at very high temperatures (1000 F). The design principles used to fabricate the pressure sensor are outlined and results are presented of its high temperature performance.

  16. Cyclic Oxidation of High-Temperature Alloy Wires in Air

    NASA Technical Reports Server (NTRS)

    Reigel, Marissa M.

    2004-01-01

    High-temperature alloy wires are proposed for use in seal applications for future re-useable space vehicles. These alloys offer the potential for improved wear resistance of the seals. The wires must withstand the high temperature environments the seals are subjected to as well as maintain their oxidation resistance during the heating and cooling cycles of vehicle re-entry. To model this, the wires were subjected to cyclic oxidation in stagnant air. of this layer formation is dependent on temperature. Slow growing oxides such as chromia and alumina are desirable. Once the oxide is formed it can prevent the metal from further reacting with its environment. Cyclic oxidation models the changes in temperature these wires will undergo in application. Cycling the temperature introduces thermal stresses which can cause the oxide layer to break off. Re-growth of the oxide layer consumes more metal and therefore reduces the properties and durability of the material. were used for cyclic oxidation testing. The baseline material, Haynes 188, has a Co base and is a chromia former while the other two alloys, Kanthal A1 and PM2000, both have a Fe base and are alumina formers. Haynes 188 and Kanthal A1 wires are 250 pm in diameter and PM2000 wires are 150 pm in diameter. The coiled wire has a total surface area of 3 to 5 sq cm. The wires were oxidized for 11 cycles at 1204 C, each cycle containing a 1 hour heating time and a minimum 20 minute cooling time. Weights were taken between cycles. After 11 cycles, one wire of each composition was removed for analysis. The other wire continued testing for 70 cycles. Post-test analysis includes X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) for phase identification and morphology.

  17. Hydrogen Production from Nuclear Energy via High Temperature Electrolysis

    SciTech Connect

    James E. O'Brien; Carl M. Stoots; J. Stephen Herring; Grant L. Hawkes

    2006-04-01

    This paper presents the technical case for high-temperature nuclear hydrogen production. A general thermodynamic analysis of hydrogen production based on high-temperature thermal water splitting processes is presented. Specific details of hydrogen production based on high-temperature electrolysis are also provided, including results of recent experiments performed at the Idaho National Laboratory. Based on these results, high-temperature electrolysis appears to be a promising technology for efficient large-scale hydrogen production.

  18. Reactions of 3-OXETANONE at High Temperatures

    NASA Astrophysics Data System (ADS)

    Wright, Emily; Warner, Brian; Foreman, Hannah; Urness, Kimberly N.; McCunn, Laura R.

    2015-06-01

    The pyrolysis of 3-oxetanone, O(CH2)2CO, has been studied in a resistively heated SiC tubular reactor at 400-1200 °C. Products of pyrolysis were identified via matrix-isolation FTIR spectroscopy and photoionization mass spectrometry in separate experiments. While 3-oxetanone is expected to dissociate into ketene and formaldehyde, these experiments show that ethylene oxide and carbon monoxide are also produced. Methyl radical and ethylene were observed as additional products and are thought to be the result of reactions involving ethylene oxide.

  19. Laser Brazing of High Temperature Braze Alloy

    NASA Technical Reports Server (NTRS)

    Gao, Y. P.; Seaman, R. F.; McQuillan, T. J.; Martiens, R. F.

    2000-01-01

    The Space Shuttle Main Engine (SSME) consists of 1080 conical tubes, which are furnace brazed themselves, manifolds, and surrounding structural jacket making almost four miles of braze joints. Subsequent furnace braze cycles are performed due to localized braze voids between the coolant tubes. SSME nozzle experiences extremely high heat flux (180 mW/sq m) during hot fire. Braze voids between coolant tubes may result in hot combustion gas escape causing jacket bulges. The nozzle can be disqualified for flight or result in mission failure if the braze voids exceed the limits. Localized braze processes were considered to eliminate braze voids, however, damage to the parent materials often prohibited use of such process. Being the only manned flight reusable rocket engine, it has stringent requirement on the braze process. Poor braze quality or damage to the parent materials limits the nozzle service life. The objective of this study was to develop a laser brazing process to provide quality, localized braze joints without adverse affect on the parent materials. Gold (Au-Cu-Ni-Pd-Mn) based high temperature braze alloys were used in both powder and wire form. Thin section iron base superalloy A286 tube was used as substrate materials. Different Laser Systems including CO2 (10.6 micrometers, 1kW), ND:YAG (1.06 micrometers, 4kW). and direct diode laser (808nm. 150W) were investigated for brazing process. The laser process variables including wavelength. laser power, travel speed and angle of inclination were optimized according to bead geometry and braze alloy wetting at minimum heat input level, The properties of laser brazing were compared to that of furnace brazing. Microhardness profiles were used for braze joint property comparison between laser and furnace brazing. The cooling rate of laser brazing was compared to furnace brazing based on secondary dendritic arm spacing, Both optical and Scanning Electron Microscope (SEM) were used to evaluate the microstructures of

  20. High-temperature LDV seed particle development

    NASA Technical Reports Server (NTRS)

    Frish, Michael B.; Pierce, Vicky G.

    1989-01-01

    The feasibility of developing a method for making monodisperse, unagglomerated spherical particles greater than 50 nm in diameter was demonstrated. Carbonaceous particles were made by pyrolyzing ethylene with a pulsed CO2 laser, thereby creating a non-equilibrium mixture of carbon, hydrogen, hydrocarbon vapors, and unpyrolyzed ethylene. Via a complex series of reactions, the carbon and hydrocarbon vapors quickly condensed into the spherical particles. By cooling and dispersing them in a supersonic expansion immediately after their creation, the hot newly-formed spheres were prevented from colliding and coalescing, thus preventing the problem of agglomeration which as plagued other investigators studying laser-simulated particle formation. The cold particles could be left suspended in the residual gases indefinitely without agglomerating. Their uniform sizes and unagglomerated nature were visualized by collecting the particles on filters that were subsequently examined using electron microscopy. It was found the mean particle size can be coarsely controlled by varying the initial ethylene pressure, and can be finely controlled by varying the fluence (energy/unit area) with which the laser irradiates the gas. The motivating application for this research was to manufacture particles that could be used as laser Doppler velocimetry (LDV) seeds in high-temperature high-speed flows. Though the particles made in this program will not evaporate until heated to about 3000 K, and thus could serve as LDV seeds in some applications, they are not ideal when the hot atmosphere is also oxidizing. In that situation, ceramic materials would be preferable. Research performed elsewhere has demonstrated that selected ceramic materials can be manufactured by laser pyrolysis of appropriate supply gases. It is anticipated that, when the same gases are used in conjunction with the rapid cooling technique, unagglomerated spherical ceramic particles can be made with little difficulty. Such

  1. High temperature inorganic membranes for separating hydrogen

    SciTech Connect

    Fain, D.E.; Roettger, G.E.

    1995-08-01

    Effort has continued to accumulate data on the transport of gases over the temperature range from room temperature to 275{degrees}C with inorganic membranes having a range of pore radii from approximately 0.25 nm to 3 mn. An experimental alumina membrane having an estimated mean pore radius of 0.25 nm has been fabricated and tested. Extensive testing of this membrane indicated that the separation factor for helium and carbon tetrafluoride at 250{degrees}C was 59 and the extrapolated high temperature separation factor was 1,193. For safety reasons, earlier flow measurements concentrated on helium, carbon dioxide, and carbon tetrafluoride. New data have been acquired with hydrogen to verify the agreement with the other gases. During the measurements with hydrogen, it was noted that a considerable amount of moisture was present in the test gas. The source of this moisture and its effect on permeance was examined. Improvements were implemented to the flow test system to minimize the water content of the hydrogen test gas, and subsequent flow measurements have shown excellent results with hydrogen. The extrapolation of separation factors as a function of temperature continues to show promise as a means of using the hard sphere model to determine the pore size of membranes. The temperature dependence of helium transport through membranes appears to be considerably greater than other gases for the smallest pore sizes. The effort to extend temperature dependence to the hard sphere model continues to be delayed, primarily because of a lack of adequate adsorption data.

  2. High-temperature Ionization in Protoplanetary Disks

    NASA Astrophysics Data System (ADS)

    Desch, Steven J.; Turner, Neal J.

    2015-10-01

    We calculate the abundances of electrons and ions in the hot (≳500 K), dusty parts of protoplanetary disks, treating for the first time the effects of thermionic and ion emission from the dust grains. High-temperature ionization modeling has involved simply assuming that alkali elements such as potassium occur as gas-phase atoms and are collisionally ionized following the Saha equation. We show that the Saha equation often does not hold, because free charges are produced by thermionic and ion emission and destroyed when they stick to grain surfaces. This means the ionization state depends not on the first ionization potential of the alkali atoms, but rather on the grains’ work functions. The charged species’ abundances typically rise abruptly above about 800 K, with little qualitative dependence on the work function, gas density, or dust-to-gas mass ratio. Applying our results, we find that protoplanetary disks’ dead zone, where high diffusivities stifle magnetorotational turbulence, has its inner edge located where the temperature exceeds a threshold value ≈1000 K. The threshold is set by ambipolar diffusion except at the highest densities, where it is set by Ohmic resistivity. We find that the disk gas can be diffusively loaded onto the stellar magnetosphere at temperatures below a similar threshold. We investigate whether the “short-circuit” instability of current sheets can operate in disks and find that it cannot, or works only in a narrow range of conditions; it appears not to be the chondrule formation mechanism. We also suggest that thermionic emission is important for determining the rate of Ohmic heating in hot Jupiters.

  3. HIGH-TEMPERATURE IONIZATION IN PROTOPLANETARY DISKS

    SciTech Connect

    Desch, Steven J.; Turner, Neal J.

    2015-10-01

    We calculate the abundances of electrons and ions in the hot (≳500 K), dusty parts of protoplanetary disks, treating for the first time the effects of thermionic and ion emission from the dust grains. High-temperature ionization modeling has involved simply assuming that alkali elements such as potassium occur as gas-phase atoms and are collisionally ionized following the Saha equation. We show that the Saha equation often does not hold, because free charges are produced by thermionic and ion emission and destroyed when they stick to grain surfaces. This means the ionization state depends not on the first ionization potential of the alkali atoms, but rather on the grains’ work functions. The charged species’ abundances typically rise abruptly above about 800 K, with little qualitative dependence on the work function, gas density, or dust-to-gas mass ratio. Applying our results, we find that protoplanetary disks’ dead zone, where high diffusivities stifle magnetorotational turbulence, has its inner edge located where the temperature exceeds a threshold value ≈1000 K. The threshold is set by ambipolar diffusion except at the highest densities, where it is set by Ohmic resistivity. We find that the disk gas can be diffusively loaded onto the stellar magnetosphere at temperatures below a similar threshold. We investigate whether the “short-circuit” instability of current sheets can operate in disks and find that it cannot, or works only in a narrow range of conditions; it appears not to be the chondrule formation mechanism. We also suggest that thermionic emission is important for determining the rate of Ohmic heating in hot Jupiters.

  4. Geochemistry of Aluminum in High Temperature Brines

    SciTech Connect

    Benezeth, P.; Palmer, D.A.; Wesolowski, D.J.

    1999-05-18

    The objective ofthis research is to provide quantitative data on the equilibrium and thermodynamic properties of aluminum minerals required to model changes in permeability and brine chemistry associated with fluid/rock interactions in the recharge, reservoir, and discharge zones of active geothermal systems. This requires a precise knowledge of the thermodynamics and speciation of aluminum in aqueous brines, spanning the temperature and fluid composition rangesencountered in active systems. The empirical and semi-empirical treatments of the solubility/hydrolysis experimental results on single aluminum mineral phases form the basis for the ultimate investigation of the behavior of complex aluminosilicate minerals. The principal objective in FY 1998 was to complete the solubility measurements on boehmite (AIOOH) inNaC1 media( 1 .O and 5.0 molal ionic strength, IOO-250°C). However, additional measurements were also made on boehmite solubility in pure NaOH solutions in order to bolster the database for fitting in-house isopiestic data on this system. Preliminary kinetic Measurements of the dissolution/precipitation of boehmite was also carried out, although these were also not planned in the earlier objective. The 1999 objectives are to incorporate these treatments into existing codes used by the geothermal industry to predict the chemistry ofthe reservoirs; these calculations will be tested for reliability against our laboratory results and field observations. Moreover, based on the success of the experimental methods developed in this program, we intend to use our unique high temperature pH easurement capabilities to make kinetic and equilibrium studies of pH-dependent aluminosilicate transformation reactions and other pH-dependent heterogeneous reactions.

  5. High-temperature metal-organic magnets.

    PubMed

    Jain, Rajsapan; Kabir, Khayrul; Gilroy, Joe B; Mitchell, Keith A R; Wong, Kin-chung; Hicks, Robin G

    2007-01-18

    For over two decades there have been intense efforts aimed at the development of alternatives to conventional magnets, particularly materials comprised in part or wholly of molecular components. Such alternatives offer the prospect of realizing magnets fabricated through controlled, low-temperature, solution-based chemistry, as opposed to high-temperature metallurgical routes, and also the possibility of tuning magnetic properties through synthesis. However, examples of magnetically ordered molecular materials at or near room temperature are extremely rare, and the properties of these materials are often capricious and difficult to reproduce. Here we present a versatile solution-based route to a new class of metal-organic materials exhibiting magnetic order well above room temperature. Reactions of the metal (M) precursor complex bis(1,5-cyclooctadiene)nickel with three different organics A-TCNE (tetracyanoethylene), TCNQ (7,7,8,8-tetracyanoquinodimethane) or DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone)--proceed via electron transfer from nickel to A and lead to materials containing Ni(II) ions and reduced forms of A in a 2:1 Ni:A ratio--that is, opposite to that of conventional (low Curie temperature) MA(2)-type magnets. These materials also contain oxygen-based species within their architectures. Magnetic characterization of the three compounds reveals spontaneous field-dependent magnetization and hysteresis at room temperature, with ordering temperatures well above ambient. The unusual stoichiometry and striking magnetic properties highlight these three compounds as members of a class of stable magnets that are at the interface between conventional inorganic magnets and genuine molecule-based magnets.

  6. High-Temperature Adhesive Strain Gage Developed

    NASA Technical Reports Server (NTRS)

    Pereira, J. Michael; Roberts, Gary D.

    1997-01-01

    Researchers at the NASA Lewis Research Center have developed a unique strain gage and adhesive system for measuring the mechanical properties of polymers and polymer composites at elevated temperatures. This system overcomes some of the problems encountered in using commercial strain gages and adhesives. For example, typical commercial strain gage adhesives require a postcure at temperatures substantially higher than the maximum test temperature. The exposure of the specimen to this temperature may affect subsequent results, and in some cases may be higher than the glass-transition temperature of the polymer. In addition, although typical commercial strain gages can be used for short times at temperatures up to 370 C, their long-term use is limited to 230 C. This precludes their use for testing some high-temperature polyimides near their maximum temperature capability. Lewis' strain gage and adhesive system consists of a nonencapsulated, unbacked gage grid that is bonded directly to the polymer after the specimen has been cured but prior to the normal postcure cycle. The gage is applied with an adhesive specially formulated to cure under the specimen postcure conditions. Special handling, mounting, and electrical connection procedures were developed, and a fixture was designed to calibrate each strain gage after it was applied to a specimen. A variety of tests was conducted to determine the performance characteristics of the gages at elevated temperatures on PMR-15 neat resin and titanium specimens. For these tests, which included static tension, thermal exposure, and creep tests, the gage and adhesive system performed within normal strain gage specifications at 315 C. An example of the performance characteristics of the gage can be seen in the figure, which compares the strain gage measurement on a polyimide specimen at 315 C with an extensometer measurement.

  7. Spectroscopic diagnostics of high temperature plasmas

    SciTech Connect

    Moos, W.

    1990-01-01

    A three-year research program for the development of novel XUV spectroscopic diagnostics for magnetically confined fusion plasmas is proposed. The new diagnostic system will use layered synthetic microstructures (LSM) coated, flat and curved surfaces as dispersive elements in spectrometers and narrow band XUV filter arrays. In the framework of the proposed program we will develop impurity monitors for poloidal and toroidal resolved measurements on PBX-M and Alcator C-Mod, imaging XUV spectrometers for electron density and temperature fluctuation measurements in the hot plasma core in TEXT or other similar tokamaks and plasma imaging devices in soft x-ray light for impurity behavior studies during RF heating on Phaedrus T and carbon pellet ablation in Alcator C-Mod. Recent results related to use of multilayer in XUV plasma spectroscopy are presented. We also discuss the latest results reviewed to q{sub o} and local poloidal field measurements using Zeeman polarimetry.

  8. Potential aerospace applications of high temperature superconductors

    NASA Technical Reports Server (NTRS)

    Selim, Raouf

    1994-01-01

    The recent discovery of High Temperature Superconductors (HTS) with superconducting transition temperature, T(sub c), above the boiling point of liquid nitrogen has opened the door for using these materials in new and practical applications. These materials have zero resistance to electric current, have the capability of carrying large currents and as such have the potential to be used in high magnetic field applications. One of the space applications that can use superconductors is electromagnetic launch of payloads to low-earth-orbit. An electromagnetic gun-type launcher can be used in small payload systems that are launched at very high velocity, while sled-type magnetically levitated launcher can be used to launch larger payloads at smaller velocities. Both types of launchers are being studied by NASA and the aerospace industry. The use of superconductors will be essential in any of these types of launchers in order to produce the large magnetic fields required to obtain large thrust forces. Low Temperature Superconductor (LTS) technology is mature enough and can be easily integrated in such systems. As for the HTS, many leading companies are currently producing HTS coils and magnets that potentially can be mass-produced for these launchers. It seems that designing and building a small-scale electromagnetic launcher is the next logical step toward seriously considering this method for launching payloads into low-earth-orbit. A second potential application is the use of HTS to build sensitive portable devices for the use in Non Destructive Evaluation (NDE). Superconducting Quantum Interference Devices (SQUID's) are the most sensitive instruments for measuring changes in magnetic flux. By using HTS in SQUID's, one will be able to design a portable unit that uses liquid nitrogen or a cryocooler pump to explore the use of gradiometers or magnetometers to detect deep cracks or corrosion in structures. A third use is the replacement of Infra-Red (IR) sensor leads on

  9. Mechanically reliable surface oxides for high-temperature corrosion resistance

    SciTech Connect

    Natesan, K.; Veal, B.W.; Grimsditch, M.; Renusch, D.; Paulikas, A.P.

    1995-05-01

    Corrosion is widely recognized as being important, but an understanding of the underlying phenomena involves factors such as the chemistry and physics of early stages of oxidation, chemistry and bonding at the substrate/oxide interface, role of segregants on the strength of that bond, transport processes through scale, mechanisms of residual stress generation and relief, and fracture behavior at the oxide/substrate interface. Because of this complexity a multilaboratory program has been initiated under the auspices of the DOE Center of Excellence for the Synthesis and Processing of Advanced Materials, with strong interactions and cross-leveraging with DOE Fossil Energy and US industry. Objective is to systematically generate the knowledge required to establish a scientific basis for designing and synthesizing improved protective oxide scales/coatings (slow-growing, adherent, sound) on high-temperature materials without compromising the requisite properties of the bulk materials. The objectives of program work at Argonne are to (1) correlate actual corrosion performance with stresses, voids, segregants, interface roughness, initial stages of oxidation, and microstructures; (2) study such behavior in growing or as-grown films; and (3) define prescriptive design and synthesis routes to mechanically reliable surface oxides. Several techniques, such as Auger electron spectroscopy, X-ray diffraction, X-ray grazing incidence reflectance, grazing-angle X-ray fluorescence, optical fluorescence, and Raman spectroscopy, are used in the studies. Tne project has selected Fe-25 wt.% Cr-20 wt.% Ni and Fe-Cr-Al alloys, which are chromia- and alumina-formers respectively, for the studies. This paper presents some of the results on early stages of oxidation and on surface segregation of elements.

  10. Microstructure and High-Temperature Oxidation Behavior of Cold Gas-sprayed Ni-Al2O3 Coatings

    NASA Astrophysics Data System (ADS)

    Sirvent, P.; Cruz, D.; Múnez, C. J.; Poza, P.

    2016-04-01

    Cermet coatings are widely used for high-temperature industrial applications. This study investigates the effect of high-temperature oxidation on cold gas dynamic-sprayed Ni-Al2O3 coatings. For this purpose, high-temperature oxidation tests were performed at 520 and 640 °C. The selected exposure times were 24, 48, 72, 168, and 336 h. The microstructural evolution during exposure at high temperature was analyzed by scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), and x-ray diffraction (XRD). The oxidation kinetics was estimated by thickness measurements. The results show that the coatings protect the substrates against oxidation. In order to study possible changes in the mechanical properties of the system, Vickers microhardness experiments on the coatings and on the 10CrMo9-10 steel substrates were conducted. It was observed that hardness decreased by exposing the specimens to high temperature.

  11. The oxidation of Ba dosed Mo(100) surfaces with O/sub 2/ at moderately high temperatures

    SciTech Connect

    Rogers, J.W. Jr.; Blair, D.S.; Paffett, M.T.

    1987-01-01

    The oxidation of Mo(100) and Ba-covered Mo(100) by O/sub 2/ have been examined at moderately high temperature (700 to 1400/sup 0/K) using x-ray photoelectron spectroscopy. Results indicate that the Ba or BaO overlayer retards but does not prevent oxidation of the underlying Mo surface. The high temperature surface chemistry of the O/Ba/Mo surface is described. 11 refs., 3 figs.

  12. Moessbauer spectroscopy of the SNC meteorite Zagami

    NASA Technical Reports Server (NTRS)

    Agerkvist, D. P.; Vistisen, L.

    1993-01-01

    We have performed Mossbauer spectroscopy on two different pieces of the meteorite Zagami belonging to the group of SNC meteorites. In one of the samples we found a substantial amount of olivine inter grown with one kind of pyroxene, and also another kind of pyroxene very similar to the pyroxene in the other sample we examined. Both samples showed less than 1 percent of Fe(3+) in the silicate phase. The group of SNC meteorites called shergottites, to which Zagami belongs, are achondrites whose texture, mineralogy and composition resembles those of terrestrial diabases. The results from the investigation are presented.

  13. High Temperature Gas-Cooled Reactor Coupled with High Temperature Steam Electrolysis

    SciTech Connect

    Oh, Chang H.; Davis, Cliff; Kim, Eung S.; Sherman, Steven; Barner, Robert; Vilim, R.

    2007-07-01

    The US Department of Energy is investigating the use of high-temperature gas-cooled reactors (HTGR) to produce electricity and hydrogen. Although the hydrogen production processes using the nuclear energy are in an early stage of development, coupling hydrogen plant to HTGR requires both efficient heat transfer and adequate separation of the facilities to assure that off-normal events in the production facility do not impact the nuclear plant. In anticipation of the design, development and procurement of an advanced power conversion system for HTGR, this study was initiated to identify the major design and technology options and their tradeoffs in the evaluation of power conversion unit (PCU) coupled to the hydrogen plant. In this study, we investigated a number of design configurations and performed thermal hydraulic analyses using various working fluids and various conditions. Also using the high temperature steam electrolysis process (HTSE), we calculated the energy requirement for the operation of the HTSE. The balance of the plant of the HTSE was developed and the HTGR was modeled to be coupled with the HTSE. This paper presents a portion of results obtained from this study. (authors)

  14. Scaling Studies for High Temperature Test Facility and Modular High Temperature Gas-Cooled Reactor

    SciTech Connect

    Richard R. Schult; Paul D. Bayless; Richard W. Johnson; James R. Wolf; Brian Woods

    2012-02-01

    The Oregon State University (OSU) High Temperature Test Facility (HTTF) is an integral experimental facility that will be constructed on the OSU campus in Corvallis, Oregon. The HTTF project was initiated, by the U.S. Nuclear Regulatory Commission (NRC), on September 5, 2008 as Task 4 of the 5-year High Temperature Gas Reactor Cooperative Agreement via NRC Contract 04-08-138. Until August, 2010, when a DOE contract was initiated to fund additional capabilities for the HTTF project, all of the funding support for the HTTF was provided by the NRC via their cooperative agreement. The U.S. Department of Energy (DOE) began their involvement with the HTTF project in late 2009 via the Next Generation Nuclear Plant (NGNP) project. Because the NRC's interests in HTTF experiments were only centered on the depressurized conduction cooldown (DCC) scenario, NGNP involvement focused on expanding the experimental envelope of the HTTF to include steady-state operations and also the pressurized conduction cooldown (PCC).

  15. High-Temperature Experiments using a Resistively-Heated High-Pressure Membrane Diamond Anvil Cell

    SciTech Connect

    Jenei, Z; Visbeck, K; Cynn, H; Yoo, C; Evans, W

    2009-04-22

    A reliable high-performance heating method using resistive heaters and a membrane driven diamond anvil cell (mDAC) is presented. Two micro-heaters are mounted in a mDAC and use electrical power of less than 150 W to achieve sample temperatures up to 1200 K. For temperature measurement we use two K-type thermocouples mounted near the sample. The approach can be used for in-situ Raman spectroscopy and x-ray diffraction at high pressures and temperatures. A W-Re alloy gasket material permits stable operation of mDAC at high temperature. Using this method, we made an isothermal compression at 900 K to pressures in excess of 100 GPa and isobaric heating at 95 GPa to temperatures in excess of 1000 K. As an example, we present high temperature Raman spectroscopy measurements of nitrogen at high pressures.

  16. ATOMIC AND MOLECULAR PHYSICS: High-Temperature Raman Investigation on Phase Transition of LBO Crystal

    NASA Astrophysics Data System (ADS)

    Zhang, Xia; Wan, Song-Ming; Yin, Shao-Tang; You, Jing-Lin

    2009-11-01

    The high-temperature Raman spectroscopy technique is applied to investigate the phase transition of LiB3O5 crystal. The result shows that the crystal is stable in the range of 293-893 K. When the temperature increases up to above 1107K, the phase transition occurs. In the liquid phase, Li2B4O7 crystal precipitates out. Up to 1173K, the Li2B4O7 crystal disappears in the melt.

  17. First high-temperature electronics products survey 2005.

    SciTech Connect

    Normann, Randy Allen

    2006-04-01

    On April 4-5, 2005, a High-Temperature Electronics Products Workshop was held. This workshop engaged a number of governmental and private industry organizations sharing a common interest in the development of commercially available, high-temperature electronics. One of the outcomes of this meeting was an agreement to conduct an industry survey of high-temperature applications. This report covers the basic results of this survey.

  18. Alternative Processing Methods for Ultra High Temperature Ceramics

    NASA Technical Reports Server (NTRS)

    Gusman, Michael; Beckman, Sarah; Gasch, Matthew; Ellerby, Don; Lau, Kai-Hung; Sanjurjo, Angel; Johnson, Sylvia M.; Venkatapathy, Ethiras (Technical Monitor)

    2002-01-01

    Ultra High Temperature Ceramics (UHTCs) are being developed for possible use in a number of structural applications including hypersonic vehicles, engines, plasma arc electrodes and high temperature shielding. Alternative methods of processing Ultra High Temperature Ceramics (UHTCs) will be discussed. Techniques that may improve oxidation resistance, strength, and reduce the processing temperature of the UHTCs will be presented. Hot-pressed UHTCs made using either milled/uncoated powders or non-milled coated powders will be compared.

  19. Refractory thermowell for continuous high temperature measurement of molten metal

    DOEpatents

    Thiesen, Todd J.

    1992-01-01

    An apparatus for the continuous high temperature measurement of materials in vessels lined with rammed or cast refractory materials. A refractory housing member is integral with the refractory lining of the vessel and contains a plurality of high temperature sensing means, such as thermocouples. A face of the housing is flush with the refractory lining and contacts the high temperature material contained in the vessel. Continuous temperature measurement is achieved by a means which is coupled to the thermocouples for indicating the temperature.

  20. Nonlinear Constitutive Relations for High Temperature Application, 1984

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Nonlinear constitutive relations for high temperature applications were discussed. The state of the art in nonlinear constitutive modeling of high temperature materials was reviewed and the need for future research and development efforts in this area was identified. Considerable research efforts are urgently needed in the development of nonlinear constitutive relations for high temperature applications prompted by recent advances in high temperature materials technology and new demands on material and component performance. Topics discussed include: constitutive modeling, numerical methods, material testing, and structural applications.

  1. ANALYSIS OF A HIGH TEMPERATURE GAS-COOLED REACTOR POWERED HIGH TEMPERATURE ELECTROLYSIS HYDROGEN PLANT

    SciTech Connect

    M. G. McKellar; E. A. Harvego; A. M. Gandrik

    2010-11-01

    An updated reference design for a commercial-scale high-temperature electrolysis (HTE) plant for hydrogen production has been developed. The HTE plant is powered by a high-temperature gas-cooled reactor (HTGR) whose configuration and operating conditions are based on the latest design parameters planned for the Next Generation Nuclear Plant (NGNP). The current HTGR reference design specifies a reactor power of 600 MWt, with a primary system pressure of 7.0 MPa, and reactor inlet and outlet fluid temperatures of 322°C and 750°C, respectively. The reactor heat is used to produce heat and electric power to the HTE plant. A Rankine steam cycle with a power conversion efficiency of 44.4% was used to provide the electric power. The electrolysis unit used to produce hydrogen includes 1.1 million cells with a per-cell active area of 225 cm2. The reference hydrogen production plant operates at a system pressure of 5.0 MPa, and utilizes a steam-sweep system to remove the excess oxygen that is evolved on the anode (oxygen) side of the electrolyzer. The overall system thermal-to-hydrogen production efficiency (based on the higher heating value of the produced hydrogen) is 42.8% at a hydrogen production rate of 1.85 kg/s (66 million SCFD) and an oxygen production rate of 14.6 kg/s (33 million SCFD). An economic analysis of this plant was performed with realistic financial and cost estimating The results of the economic analysis demonstrated that the HTE hydrogen production plant driven by a high-temperature helium-cooled nuclear power plant can deliver hydrogen at a competitive cost. A cost of $3.03/kg of hydrogen was calculated assuming an internal rate of return of 10% and a debt to equity ratio of 80%/20% for a reactor cost of $2000/kWt and $2.41/kg of hydrogen for a reactor cost of $1400/kWt.

  2. Effects of electron irradiation on high temperature superconductors and contacts to high temperature superconductors

    NASA Technical Reports Server (NTRS)

    Caton, Randall

    1988-01-01

    The discovery of a new class of ceramic superconductors with transition temperatures above liquid nitrogen has opened the doors for exciting space applications. Energy storage, pointing maneuvers, magnetic shielding, and sensitive detection of electromagnetic radiation are some of the longer term possible applications. One near term application involves low electrical resistance, high thermal resistance connections between a detector operating at approximatly or equal to 4 and the electronics operating at approximatly or equal to 77 K. The new high temperature superconductors could accomplish this providing the necessary electrical connections to the ground plane while isolating the system thermally, thus prolonging the life of the mission. With such possibilities it is clearly of value to study the effects of radiation that would be experienced during a typical space mission. In this work we focused specifically on the effects of the electron radiation environment.

  3. Generating high temperature tolerant transgenic plants: Achievements and challenges.

    PubMed

    Grover, Anil; Mittal, Dheeraj; Negi, Manisha; Lavania, Dhruv

    2013-05-01

    Production of plants tolerant to high temperature stress is of immense significance in the light of global warming and climate change. Plant cells respond to high temperature stress by re-programming their genetic machinery for survival and reproduction. High temperature tolerance in transgenic plants has largely been achieved either by over-expressing heat shock protein genes or by altering levels of heat shock factors that regulate expression of heat shock and non-heat shock genes. Apart from heat shock factors, over-expression of other trans-acting factors like DREB2A, bZIP28 and WRKY proteins has proven useful in imparting high temperature tolerance. Besides these, elevating the genetic levels of proteins involved in osmotic adjustment, reactive oxygen species removal, saturation of membrane-associated lipids, photosynthetic reactions, production of polyamines and protein biosynthesis process have yielded positive results in equipping transgenic plants with high temperature tolerance. Cyclic nucleotide gated calcium channel proteins that regulate calcium influxes across the cell membrane have recently been shown to be the key players in induction of high temperature tolerance. The involvement of calmodulins and kinases in activation of heat shock factors has been implicated as an important event in governing high temperature tolerance. Unfilled gaps limiting the production of high temperature tolerant transgenic plants for field level cultivation are discussed.

  4. High-Temperature Cyclic Oxidation Data, Volume 1

    NASA Technical Reports Server (NTRS)

    Barrett, C. A.; Garlick, R. G.; Lowell, C. E.

    1984-01-01

    This first in a series of cyclic oxidation handbooks contains specific-weight-change-versus-time data and X-ray diffraction results derived from high-temperature cyclic tests on high-temperature, high-strength nickel-base gamma/gamma' and cobalt-base turbine alloys. Each page of data summarizes a complete test on a given alloy sample.

  5. Research On Bi-Based High-Temperature Superconductors

    NASA Technical Reports Server (NTRS)

    Banks, Curtis; Doane, George B., III; Golben, John

    1993-01-01

    Brief report describes effects of melt sintering on Bi-based high-temperature superconductor system, as well as use of vibrating-sample magnetometer to determine hysteresis curves at 77 K for partially melt-sintered samples. Also discussed is production of high-temperature superconducting thin films by laser ablation: such films potentially useful in detection of signals of very low power.

  6. High temperature heat exchange: nuclear process heat applications

    SciTech Connect

    Vrable, D.L.

    1980-09-01

    The unique element of the HTGR system is the high-temperature operation and the need for heat exchanger equipment to transfer nuclear heat from the reactor to the process application. This paper discusses the potential applications of the HTGR in both synthetic fuel production and nuclear steel making and presents the design considerations for the high-temperature heat exchanger equipment.

  7. High temperature cyclic oxidation data. Part 1: Turbine alloys

    NASA Technical Reports Server (NTRS)

    Barrett, Charles A.; Garlick, Ralph G.; Lowell, Carl E.

    1989-01-01

    Specific-weight-change-versus-time data and x ray diffraction results are presented derived from high temperature cyclic tests on high temperature, high strength nickel-base gamma/gamma prime and cobalt-base turbine alloys. Each page of data summarizes a complete test on a given alloy sample.

  8. 46 CFR 56.60-5 - Steel (High temperature applications).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Steel (High temperature applications). 56.60-5 Section... SYSTEMS AND APPURTENANCES Materials § 56.60-5 Steel (High temperature applications). (a) (Reproduces 124.2.A.) Upon prolonged exposure to temperatures above 775 °F (412 °C), the carbide phase of plain...

  9. 46 CFR 56.60-5 - Steel (High temperature applications).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Steel (High temperature applications). 56.60-5 Section... SYSTEMS AND APPURTENANCES Materials § 56.60-5 Steel (High temperature applications). (a) (Reproduces 124.2.A.) Upon prolonged exposure to temperatures above 775 °F (412 °C), the carbide phase of plain...

  10. 46 CFR 56.60-5 - Steel (High temperature applications).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Steel (High temperature applications). 56.60-5 Section... SYSTEMS AND APPURTENANCES Materials § 56.60-5 Steel (High temperature applications). (a) (Reproduces 124.2.A.) Upon prolonged exposure to temperatures above 775 °F (412 °C), the carbide phase of plain...

  11. High Temperature Evaluation of Tantalum Capacitors - Test 1

    DOE Data Explorer

    Cieslewski, Grzegorz

    2014-09-28

    Tantalum capacitors can provide much higher capacitance at high-temperatures than the ceramic capacitors. This study evaluates selected tantalum capacitors at high temperatures to determine their suitability for you in geothermal field. This data set contains results of the first test where three different types of capacitors were evaluated at 260C.

  12. 46 CFR 56.60-5 - Steel (High temperature applications).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... SYSTEMS AND APPURTENANCES Materials § 56.60-5 Steel (High temperature applications). (a) (Reproduces 124.2... 46 Shipping 2 2010-10-01 2010-10-01 false Steel (High temperature applications). 56.60-5 Section... design temperature of a piping system employing one or more of the materials listed in paragraphs (a),...

  13. 46 CFR 56.60-5 - Steel (High temperature applications).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... SYSTEMS AND APPURTENANCES Materials § 56.60-5 Steel (High temperature applications). (a) (Reproduces 124.2... 46 Shipping 2 2011-10-01 2011-10-01 false Steel (High temperature applications). 56.60-5 Section... design temperature of a piping system employing one or more of the materials listed in paragraphs (a),...

  14. High-temperature cyclic oxidation data. Part 2: Turbine alloys

    NASA Technical Reports Server (NTRS)

    Barrett, Charles A.; Garlick, Ralph G.

    1989-01-01

    Specific-weight-change-versus-time data and x ray diffraction results are presented derived from high temperature cyclic tests on high temperature, high strength nickel-base gamma/gamma prime and cobalt-base turbine alloys. Each page of data summarizes a complete test on a given alloy sample.

  15. High-temperature study of defects and homogeneity in glass

    NASA Astrophysics Data System (ADS)

    Yoon, Chang Hyun

    Glass frit has many useful applications in the glass and ceramic industries. Several attempts were made in this study to understand the origin of problems that generally occur when using glass frit. The effect of water/glass interactions on the rheology of glass suspension and the final properties of glass and glaze were studied. The dissolution of refractory inclusions and its influence on the bubble evolution, glass structure, and homogeneity of the resulting melt were also studied. The effects of long-term interaction of water with various frit suspensions were considered. The change in suspension rheology is associated with the ion concentration of the frit suspension, which strongly depends on the frit composition, additives, and solid content of frit suspension. Physical property and compositional variations resulted from dealkalization reactions between the frit particles and water. New investigative techniques for continuous monitoring and quantitative analysis of the dissolution of refractory inclusions in glass have been developed utilizing high-temperature microscopy with computer image analysis. The dissolution rates of refractory oxides in glass frit were measured utilizing hot-stage microscopy in the temperature range from 1050°C to 1400°C. The effects of dissolution on the structure of the final glass, were monitored by infrared spectroscopy. Homogenization of the resulting melts was studied using a Christiansen filter. It was found that melting temperature and time strongly influence the dissolution of refractory batch materials and subsequent homogenization rates, leading to large differences in final structures for glass melts and glazes which have not attained equilibrium.

  16. High temperature corrosion behavior of commercial high temperature alloys under deposits of alkali salts

    SciTech Connect

    Kloewer, J.

    1995-12-31

    Corrosive deposits containing high amounts of alkali sulphates, chlorides and/or carbonates are encountered by heat exchanger tubes in a variety of industrial processes. Due to their low melting point the alkali salts can cause basic or acidic dissolution of the subjacent material, which results in rapid wastage of the tube. In order to select appropriate materials for application in heat recovery systems eight commercial high temperature materials (alloy 800H, Alloy 31, Alloy AC66, alloy 45-TM, Alloy 625, Alloy 59 and Alloy C-4) were investigated in sulphate, sulphate/chloride and sulphate/chloride/carbonate salt mixtures. The temperature range was between 550 and 750 C. In agreement with field tests the corrosion attack was high for most of the alloys tested with the corrosion rate depending sensitively on salt composition, test temperature and alloy composition. High molybdenum contents were found to be detrimental. Chromium did not effect the corrosion behavior significantly, whereas silicon had a beneficial effect on the corrosion resistance in molten alkali salts.

  17. High-temperature processing of cuprate oxide superconductors

    NASA Technical Reports Server (NTRS)

    Wu, M. K.; Ashburn, J. R.; Higgins, C. A.; Fellows, C. W.; Loo, B. H.; Burns, D. H.; Ibrahim, A.; Rolin, T. D.; Peters, P. N.; Sisk, R. C.

    1988-01-01

    Superconducting Y1Ba2Cu3O7 ('123') films were fabricated on the Y2BaCuO5 ('211') phase substrate. The superconducting characteristics of these films, in terms of superconducting transition temperature (Tc) and width, are better than those using other oxide compounds as substrates. In addition, using high-temperature processing, the bulk 211 phase was converted into the 123 phase. A new high Tc copper oxide material with non-rare-earth elements (Bi-Sr-Cu-O) was prepared using similar high-temperature processing. High-temperature processing presents an alternative synthetic route in the search of new high Tc superconductors.

  18. Thermomagnetic phenomena in the mixed state of high temperature superconductors

    NASA Technical Reports Server (NTRS)

    Meilikhov, E. Z.

    1995-01-01

    Galvano- and thermomagnetic-phenomena in high temperature superconductors, based on kinetic coefficients, are discussed, along with a connection between the electric field and the heat flow in superconductor mixed state. The relationship that determines the transport coefficients of high temperature superconductors in the mixed state based on Seebeck and Nernst effects is developed. It is shown that this relationship is true for a whole transition region of the resistive mixed state of a superconductor. Peltier, Ettingshausen and Righi-Leduc effects associated with heat conductivity as related to high temperature superconductors are also addressed.

  19. Method for Synthesizing Extremeley High Temperature Melting Materials

    SciTech Connect

    Saboungi, Marie-Louise and Glorieux, Benoit

    2005-11-22

    The invention relates to a method of synthesizing high-temperature melting materials. More specifically the invention relates to a containerless method of synthesizing very high temperature melting materials such as borides, carbides and transition-metal, lanthanide and actinide oxides, using an Aerodynamic Levitator and a laser. The object of the invention is to provide a method for synthesizing extremely high-temperature melting materials that are otherwise difficult to produce, without the use of containers, allowing the manipulation of the phase (amorphous/crystalline/metastable) and permitting changes of the environment such as different gaseous compositions.

  20. Computational technology for high-temperature aerospace structures

    NASA Technical Reports Server (NTRS)

    Noor, A. K.; Card, M. F.

    1992-01-01

    The status and some recent developments of computational technology for high-temperature aerospace structures are summarized. Discussion focuses on a number of aspects including: goals of computational technology for high-temperature structures; computational material modeling; life prediction methodology; computational modeling of high-temperature composites; error estimation and adaptive improvement strategies; strategies for solution of fluid flow/thermal/structural problems; and probabilistic methods and stochastic modeling approaches, integrated analysis and design. Recent trends in high-performance computing environment are described and the research areas which have high potential for meeting future technological needs are identified.

  1. High-temperature ductility of electro-deposited nickel

    NASA Technical Reports Server (NTRS)

    Dini, J. W.; Johnson, H. R.

    1977-01-01

    Work done during the past several months on high temperature ductility of electrodeposited nickel is summarized. Data are presented which show that earlier measurements made at NASA-Langley erred on the low side, that strain rate has a marked influence on high temperature ductility, and that codeposition of a small amount of manganese helps to improve high temperature ductility. Influences of a number of other factors on nickel properties were also investigated. They included plating solution temperature, current density, agitation, and elimination of the wetting agent from the plating solution. Repair of a large nozzle section by nickel plating is described.

  2. A summary of high-temperature electronics research and development

    SciTech Connect

    Thome, F.V.; King, D.B.

    1991-10-18

    Current and future needs in automative, aircraft, space, military, and well logging industries require operation of electronics at higher temperatures than today's accepted limit of 395 K. Without the availability of high-temperature electronics, many systems must operate under derated conditions or must accept severe mass penalties required by coolant systems to maintain electronic temperatures below critical levels. This paper presents ongoing research and development in the electronics community to bring high-temperature electronics to commercial realization. Much of this work was recently reviewed at the First International High-Temperature Electronics Conference held 16--20 June 1991 in Albuquerque, New Mexico. 4 refs., 1 tab.

  3. Method For Synthesizing Extremely High-Temperature Melting Materials

    DOEpatents

    Saboungi, Marie-Louise; Glorieux, Benoit

    2005-11-22

    The invention relates to a method of synthesizing high-temperature melting materials. More specifically the invention relates to a containerless method of synthesizing very high temperature melting materials such as borides, carbides and transition-metal, lanthanide and actinide oxides, using an Aerodynamic Levitator and a laser. The object of the invention is to provide a method for synthesizing extremely high-temperature melting materials that are otherwise difficult to produce, without the use of containers, allowing the manipulation of the phase (amorphous/crystalline/metastable) and permitting changes of the environment such as different gaseous compositions.

  4. Method for synthesizing extremely high-temperature melting materials

    DOEpatents

    Saboungi, Marie-Louise; Glorieux, Benoit

    2007-11-06

    The invention relates to a method of synthesizing high-temperature melting materials. More specifically the invention relates to a containerless method of synthesizing very high temperature melting materials such as carbides and transition-metal, lanthanide and actinide oxides, using an aerodynamic levitator and a laser. The object of the invention is to provide a method for synthesizing extremely high-temperature melting materials that are otherwise difficult to produce, without the use of containers, allowing the manipulation of the phase (amorphous/crystalline/metastable) and permitting changes of the environment such as different gaseous compositions.

  5. High temperature microbial activity in upper soil layers.

    PubMed

    Santana, M M; Gonzalez, J M

    2015-11-01

    Biomineralization at high temperatures in upper soil layers has been largely ignored, although desertification and global warming have led to increasing areas of soils exposed to high temperatures. Recent publications evidenced thermophilic bacteria ubiquity in soils as viable cells, and their role in nutrient cycling and seedling development. High temperature events, frequently observed at medium and low latitudes, locate temporal niches for thermophiles to grow in soils. There, at temperatures inhibitory for common mesophiles, thermophilic bacteria could perform biogeochemical reactions important to the soil food web. Nutrient cycling analyses in soils at medium and low latitudes would benefit from considering the potential role of thermophiles.

  6. Use of high temperature superconductors in magnetoplasmadynamic systems

    NASA Technical Reports Server (NTRS)

    Reed, C. B.; Sovey, J. S.

    1988-01-01

    The use of Tesla-class high-temperature superconducting magnets may have an extremely large impact on critical development issues (erosion, heat transfer, and performance) related to magnetoplasmadynamic (MPD) thrusters and also may provide significant benefits in reducing the mass of magnetics used in the power processing system. These potential performance improvements, coupled with additional benefits of high-temperature superconductivity, provide a very strong motivation to develop high-temperature superconductivity (HTS) applied-field MPD thruster propulsion systems. The application of HTS to MPD thruster propulsion systems may produce an enabling technology for these electric propulsion systems. This paper summarizes the impact that HTS may have upon MPD propulsion systems.

  7. High-temperature testing of glass/ceramic matrix composites

    NASA Technical Reports Server (NTRS)

    Mandell, John F.; Grande, Dodd H.; Dannemann, Kathryn A.

    1989-01-01

    Recent advances in ceramic and other high-temperature composites have created a need for test methods that can be used at 1000 C and above. Present test methods usually require adhesively bonded tabs that cannot be used at high temperatures. This paper discusses some of the difficulties with high-temperature test development and describes several promising test methods. Stress-strain data are given for Nicalon ceramic fiber reinforced glass and glass-ceramic matrix composites tested in air at temperatures up to 1000 C.

  8. Novel high-temperature reactors for in situ studies of three-way catalysts using turbo-XAS.

    PubMed

    Guilera, Gemma; Gorges, Bernard; Pascarelli, Sakura; Vitoux, Hugo; Newton, Mark A; Prestipino, Carmelo; Nagai, Yasutaka; Hara, Naoyuki

    2009-09-01

    Two novel high-temperature reactors for in situ X-ray absorption spectroscopy (XAS) measurements in fluorescence are presented, each of them being optimized for a particular purpose. The powerful combination of these reactors with the turbo-XAS technique used in a dispersive-XAS beamline permits the study of commercial three-way catalysts under realistic gas composition and temporal conditions.

  9. Failure Mechanisms for Ceramic Matrix Textile Composites at High Temperature

    SciTech Connect

    Cox, Brian

    1999-03-01

    OAK B188 Failure Mechanisms for Ceramic Matrix Textile Composites at High Temperature. This summary refers to work done in approximately the twelve months to the present in our contract ''Failure Mechanisms for Ceramic Matrix Textile Composites at High Temperature,'' which commenced in August, 1997. Our activities have consisted mainly of measurements of creep-controlled crack growth in ceramic matrix composites (CMCS) at high temperature; imaging of deformation fields in textile CMCS; the assessment of mechanisms of damage in textile composites, especially those with through-thickness reinforcement; the formulation of models of delamination crack growth under fatigue in textile composites; analytical models of the bridging traction law for creeping fibers in a CMC at high temperature; and an analytical model of a bridging fiber tow in a textile composite.

  10. Industrial applications of MHD high temperature air heater technology

    NASA Astrophysics Data System (ADS)

    Saari, D. P.; Fenstermacher, J. E.; White, L. R.; Marksberry, C. L.

    1981-12-01

    The MHD high temperature air heater (HTAH) requires technology beyond the current state-of-the-art of industrial regenerative heaters. Specific aspects of HTAH technology which may find other application include refractory materials and valves resistant to the high temperature, corrosive, slag-bearing gas, materials resistant to cyclic thermal stresses, high temperature support structures for the cored brick bed, regenerative heater operating techniques for preventing accumulation of slag in the heater, and analytical tools for computing regenerative heater size, cost, and performance. Areas where HTAH technology may find application include acetylene/ethylene production processes, flash pyrolysis of coal, high temperature gas reactors, coal gasification processes, various metallurgical processes, waste incineration, and improvements to existing regenerator technology such as blast furnace stoves and glass tank regenerators.

  11. High-temperature superconductivity: Electron mirages in an iron salt

    NASA Astrophysics Data System (ADS)

    Zaanen, Jan

    2014-11-01

    The detection of unusual 'mirage' energy bands in photoemission spectra of single-atom layers of iron selenide reveals the probable cause of high-temperature superconductivity in these artificial structures. See Letter p.245

  12. Auxins reverse plant male sterility caused by high temperatures.

    PubMed

    Sakata, Tadashi; Oshino, Takeshi; Miura, Shinya; Tomabechi, Mari; Tsunaga, Yuta; Higashitani, Nahoko; Miyazawa, Yutaka; Takahashi, Hideyuki; Watanabe, Masao; Higashitani, Atsushi

    2010-05-11

    With global warming, plant high temperature injury is becoming an increasingly serious problem. In wheat, barley, and various other commercially important crops, the early phase of anther development is especially susceptible to high temperatures. Activation of auxin biosynthesis with increased temperatures has been reported in certain plant tissues. In contrast, we here found that under high temperature conditions, endogenous auxin levels specifically decreased in the developing anthers of barley and Arabidopsis. In addition, expression of the YUCCA auxin biosynthesis genes was repressed by increasing temperatures. Application of auxin completely reversed male sterility in both plant species. These findings suggest that tissue-specific auxin reduction is the primary cause of high temperature injury, which leads to the abortion of pollen development. Thus, the application of auxin may help sustain steady yields of crops despite future climate change.

  13. High Temperature Irradiation Resistant Thermocouple (HTIR-TC)

    ScienceCinema

    None

    2016-07-12

    INL researchers have created a new thermocouple that can resist high temperature and radiation. This device will improve safety and reduce costs associated with unit failures. Learn more about INL research at http://www.facebook.com/idahonationallaboratory

  14. High temperature dispersion strengthening of NiAl

    NASA Technical Reports Server (NTRS)

    Sherman, M.; Vedula, K.

    1986-01-01

    A potential high temperature strengthening mechanism for alloys based on the intermetallic compound NiAl was investigated. This study forms part of an overall program at NASA Lewis Research Center for exploring the potential of alloys based on NiAl for high temperature applications. An alloy containing 2.26 at% Nb and produced by hot extrusion of blended powders was examined in detail using optical and electron microscopy. Interdiffusion between the blended Nb and NiAl powders results in the formation of intermediate phases. A fine dispersion of precipitates of a hexagonal, ordered NiAlNb phases in a matrix of NiAl can be produced and this results in strengthening of the alloy by interfering with dislocation motion at high temperature. These precipitates are, however, found to coarsen during the high temperature (1300 K) deformation at slow strain rates and this may impose some limitatioins on the use of this strengthening mechanism.

  15. High-entropy alloys as high-temperature thermoelectric materials

    SciTech Connect

    Shafeie, Samrand; Guo, Sheng; Hu, Qiang; Fahlquist, Henrik; Erhart, Paul; Palmqvist, Anders

    2015-11-14

    Thermoelectric (TE) generators that efficiently recycle a large portion of waste heat will be an important complementary energy technology in the future. While many efficient TE materials exist in the lower temperature region, few are efficient at high temperatures. Here, we present the high temperature properties of high-entropy alloys (HEAs), as a potential new class of high temperature TE materials. We show that their TE properties can be controlled significantly by changing the valence electron concentration (VEC) of the system with appropriate substitutional elements. Both the electrical and thermal transport properties in this system were found to decrease with a lower VEC number. Overall, the large microstructural complexity and lower average VEC in these types of alloys can potentially be used to lower both the total and the lattice thermal conductivity. These findings highlight the possibility to exploit HEAs as a new class of future high temperature TE materials.

  16. High temperature solid electrolyte fuel cell configurations and interconnections

    DOEpatents

    Isenberg, Arnold O.

    1984-01-01

    High temperature fuel cell configurations and interconnections are made including annular cells having a solid electrolyte sandwiched between thin film electrodes. The cells are electrically interconnected along an elongated axial outer surface.

  17. High-entropy alloys as high-temperature thermoelectric materials

    NASA Astrophysics Data System (ADS)

    Shafeie, Samrand; Guo, Sheng; Hu, Qiang; Fahlquist, Henrik; Erhart, Paul; Palmqvist, Anders

    2015-11-01

    Thermoelectric (TE) generators that efficiently recycle a large portion of waste heat will be an important complementary energy technology in the future. While many efficient TE materials exist in the lower temperature region, few are efficient at high temperatures. Here, we present the high temperature properties of high-entropy alloys (HEAs), as a potential new class of high temperature TE materials. We show that their TE properties can be controlled significantly by changing the valence electron concentration (VEC) of the system with appropriate substitutional elements. Both the electrical and thermal transport properties in this system were found to decrease with a lower VEC number. Overall, the large microstructural complexity and lower average VEC in these types of alloys can potentially be used to lower both the total and the lattice thermal conductivity. These findings highlight the possibility to exploit HEAs as a new class of future high temperature TE materials.

  18. The role of creep in high temperature low cycle fatigue.

    NASA Technical Reports Server (NTRS)

    Manson, S. S.; Halford, G. R.; Spera, D. A.

    1971-01-01

    The significance of the role that creep can play in governing high-temperature, low-cycle fatigue resistance is investigated by conducting strain cycling tests on two high-temperature stainless steel alloys and making concurrent measurements of stress, temperature, and strain at various frequencies. The results are then analyzed in terms of damage imposed by creep and fatigue components. It is shown that creep can play an important and sometimes dominant role in low cycle fatigue at high temperatures. The results of the study include the findings that: (1) the simple life-fraction theory described is adequate for calculating creep damage when the cyclic creep rupture curve is used as a basis for analysis; (2) a method of universal slopes originally developed for room temperature use is sufficiently accurate at high temperature to be used to calculate pure fatigue damage; and (3) a linear creep-fatigue damage rule can explain the transitions observed from one failure mode to another.

  19. High Temperature Irradiation Resistant Thermocouple (HTIR-TC)

    SciTech Connect

    2011-01-01

    INL researchers have created a new thermocouple that can resist high temperature and radiation. This device will improve safety and reduce costs associated with unit failures. Learn more about INL research at http://www.facebook.com/idahonationallaboratory

  20. Electrical properties of teflon and ceramic capacitors at high temperatures

    NASA Technical Reports Server (NTRS)

    Hammoud, A. N.; Baumann, E. D.; Myers, I. T.; Overton, E.

    1992-01-01

    Space power systems and components are often required to operate efficiently and reliably in harsh environments where stresses, such as high temperature, are encountered. These systems must, therefore, withstand exposure to high temperature while still providing good electrical and other functional properties. Experiments were carried out to evaluate Teflon and ceramic capacitors for potential use in high temperature applications. The capacitors were characterized in terms of their capacitance and dielectric loss as a function of temperature, up to 200 C. At a given temperature, these properties were obtained in a frequency range of 50 Hz to 100 kHz. DC leakage current measurements were also performed in a temperature range from 25 to 200 C. The results obtained are discussed and conclusions are made concerning the suitability of the capacitors studied for high temperature applications.