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Sample records for thermal stability electronic

  1. Enhanced thermal stability of a polymer solar cell blend induced by electron beam irradiation in the transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Bäcke, Olof, E-mail: obacke@chalmers.se [Department of Applied Physics, Chalmers University of Technology, 41296 Göteborg (Sweden); Lindqvist, Camilla; Diaz de Zerio Mendaza, Amaia [Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296 Göteborg (Sweden); Gustafsson, Stefan [Department of Applied Physics, Chalmers University of Technology, 41296 Göteborg (Sweden); Wang, Ergang; Andersson, Mats R.; Müller, Christian [Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296 Göteborg (Sweden); Kristiansen, Per Magnus [Institute of Polymer Nanotechnology (INKA), FHNW University of Applied Science and Arts Northwestern Switzerland, 5210 Windisch (Switzerland); Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute, 5232 Villigen (Switzerland); Olsson, Eva, E-mail: eva.olsson@chalmers.se [Department of Applied Physics, Chalmers University of Technology, 41296 Göteborg (Sweden)

    2017-05-15

    We show by in situ microscopy that the effects of electron beam irradiation during transmission electron microscopy can be used to lock microstructural features and enhance the structural thermal stability of a nanostructured polymer:fullerene blend. Polymer:fullerene bulk-heterojunction thin films show great promise for use as active layers in organic solar cells but their low thermal stability is a hindrance. Lack of thermal stability complicates manufacturing and influences the lifetime of devices. To investigate how electron irradiation affects the thermal stability of polymer:fullerene films, a model bulk-heterojunction film based on a thiophene-quinoxaline copolymer and a fullerene derivative was heat-treated in-situ in a transmission electron microscope. In areas of the film that exposed to the electron beam the nanostructure of the film remained stable, while the nanostructure in areas not exposed to the electron beam underwent large phase separation and nucleation of fullerene crystals. UV–vis spectroscopy shows that the polymer:fullerene films are stable for electron doses up to 2000 kGy. - Highlights: • Thermal stability of a polymer: fullerne blend is increased using electron irradiation. • Using in-situ transmission electron microscopy the nanostructure is studied. • Electron irradiation stops phase separation between the polymer and fullerene. • Electron irradiation quenches the formation and nucleation of fullerene crystals.

  2. Enhanced thermal stability of a polymer solar cell blend induced by electron beam irradiation in the transmission electron microscope.

    Science.gov (United States)

    Bäcke, Olof; Lindqvist, Camilla; de Zerio Mendaza, Amaia Diaz; Gustafsson, Stefan; Wang, Ergang; Andersson, Mats R; Müller, Christian; Kristiansen, Per Magnus; Olsson, Eva

    2017-05-01

    We show by in situ microscopy that the effects of electron beam irradiation during transmission electron microscopy can be used to lock microstructural features and enhance the structural thermal stability of a nanostructured polymer:fullerene blend. Polymer:fullerene bulk-heterojunction thin films show great promise for use as active layers in organic solar cells but their low thermal stability is a hindrance. Lack of thermal stability complicates manufacturing and influences the lifetime of devices. To investigate how electron irradiation affects the thermal stability of polymer:fullerene films, a model bulk-heterojunction film based on a thiophene-quinoxaline copolymer and a fullerene derivative was heat-treated in-situ in a transmission electron microscope. In areas of the film that exposed to the electron beam the nanostructure of the film remained stable, while the nanostructure in areas not exposed to the electron beam underwent large phase separation and nucleation of fullerene crystals. UV-vis spectroscopy shows that the polymer:fullerene films are stable for electron doses up to 2000kGy. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Study of thermal stability of ultrafine-grained copper by means of electron back scattering diffraction

    Czech Academy of Sciences Publication Activity Database

    Man, O.; Pantělejev, L.; Kunz, Ludvík

    2010-01-01

    Roč. 51, č. 2 (2010), s. 209-213 ISSN 1345-9678 R&D Projects: GA AV ČR 1QS200410502 Institutional research plan: CEZ:AV0Z20410507 Keywords : ultra-fine grained copper * thermal stability of microstructure * electron back scattering diffraction * grain size * texture Subject RIV: JG - Metallurgy Impact factor: 0.779, year: 2010

  4. Metal-dielectric interfaces in gigascale electronics thermal and electrical stability

    CERN Document Server

    He, Ming

    2012-01-01

    Metal-dielectric interfaces are ubiquitous in modern electronics. As advanced gigascale electronic devices continue to shrink, the stability of these interfaces is becoming an increasingly important issue that has a profound impact on the operational reliability of these devices. In this book, the authors present the basic science underlying  the thermal and electrical stability of metal-dielectric interfaces and its relationship to the operation of advanced interconnect systems in gigascale electronics. Interface phenomena, including chemical reactions between metals and dielectrics, metallic-atom diffusion, and ion drift, are discussed based on fundamental physical and chemical principles. Schematic diagrams are provided throughout the book to illustrate  interface phenomena and the principles that govern them. Metal-Dielectric Interfaces in Gigascale Electronics  provides a unifying approach to the diverse and sometimes contradictory test results that are reported in the literature on metal-dielectric i...

  5. Improving the Mechanical Performance and Thermal Stability of a PVA-Clay Nanocomposite by Electron Beam Irradiation

    Science.gov (United States)

    Shokuhi Rad, A.; Ebrahimi, D.

    2017-07-01

    The effects of electron beam irradiation and presence of clay on the mechanical properties and thermal stability of montmorillonite clay-modified polyvinyl alcohol nanocomposites were studied. By using the X-ray diffraction (XRD) and transmission electron microscopy (TEM), the microstructure of the nanocomposites was investigated. The results obtained from TEM and XRD tests showed that montmorillonite clay nanoparticles were located in the polyvinyl alcohol phase. The XRD analysis confirmed the formation of an exfoliated structure in nanocomposites samples. Increasing the amount of clay to 20 wt.% increased the tensile strength and modulus of the nanocomposite. Irradiation up to an absorbed dose of 100 kGy increased its mechanical properties and thermal stability, but at higher irradiation levels, the mechanical strength and thermal stability declined. The sample with 20 wt.% of the nanofiller, exposed to 100 kGy, showed the highest mechanical strength and thermal stability.

  6. An Electron Microscope Study of the Thermal Neutron Induced Loss in High Temperature Tensile Ductility of Nb Stabilized Austenitic Steels

    Energy Technology Data Exchange (ETDEWEB)

    Roy, R B

    1965-04-15

    Irradiated {approx}3 x 10{sup 19} n/cm{sup 2} (thermal), <3 x 10{sup 18} n/cm{sup 2} (> 1 MeV) at 40 deg C and the corresponding unirradiated control tensile specimens of a 20 % Cr, 25 % Ni, Nb stabilized steel tested at 650 deg C, 750 deg C and 800 deg C have been examined by transmission electron microscopy. The results indicate that the irradiation induced embrittlement of the tensile specimens at elevated temperatures is preceded by the formation of fine precipitates within the grains. These precipitates may restrict the deformation within the grains such that the stresses are concentrated at the grain boundaries thereby leading to premature failure. It is suggested that the main effect of the irradiation is to promote conditions necessary for the formation of these precipitates, namely, super saturation and fresh nucleation sites within the matrix through the energetic emission of He and Li atoms from boron as an impurity.

  7. An Electron Microscope Study of the Thermal Neutron Induced Loss in High Temperature Tensile Ductility of Nb Stabilized Austenitic Steels

    International Nuclear Information System (INIS)

    Roy, R.B.

    1965-04-01

    Irradiated ∼3 x 10 19 n/cm 2 (thermal), 18 n/cm 2 (> 1 MeV) at 40 deg C and the corresponding unirradiated control tensile specimens of a 20 % Cr, 25 % Ni, Nb stabilized steel tested at 650 deg C, 750 deg C and 800 deg C have been examined by transmission electron microscopy. The results indicate that the irradiation induced embrittlement of the tensile specimens at elevated temperatures is preceded by the formation of fine precipitates within the grains. These precipitates may restrict the deformation within the grains such that the stresses are concentrated at the grain boundaries thereby leading to premature failure. It is suggested that the main effect of the irradiation is to promote conditions necessary for the formation of these precipitates, namely, super saturation and fresh nucleation sites within the matrix through the energetic emission of He and Li atoms from boron as an impurity

  8. Stabilized thermally compensated mirror

    International Nuclear Information System (INIS)

    Dunn, C. III; Tobin, R.D.; Bergstreser, N.E.; Heinz, T.A.

    1975-01-01

    A thermally compensated mirror is described that is formed by a laminated structure. The structure is comprised of a front plate having a reflective front surface and having a plurality of grooves formed in the rear surface for conducting coolant fluid in heat exchanging relation with said reflective surface, a rear plate having coolant inlet and coolant outlet openings extending therethrough, a minimum temperature plate interposed between said front and rear plates and formed with a plurality of coolant distribution passageways coupled to receive coolant fluid from said coolant inlet and oriented to distribute said coolant fluid in a manner to establish a minimum temperature plane parallel to said reflective surface, a temperature stabilization plate interposed between said front plate and said minimum temperature plate and formed with a plurality of coolant distribution channels coupled to receive said coolant fluid after said coolant fluid has passed in heat exchanging relation with said reflective surface and oriented to distribute said coolant fluid in a manner to establish a uniform temperature plane parallel to said reflective surface, and means for circulating said coolant fluid through said structure in a predetermined path. (U.S.)

  9. Dispersion stability of thermal nanofluids

    Directory of Open Access Journals (Sweden)

    Fan Yu

    2017-10-01

    Full Text Available Thermal nanofluids, the engineered fluids with dispersed functional nanoparticles, have exhibited extraordinary thermophysical properties and added functionalities, and thus have enabled a broad range of important applications. The poor dispersion stability of thermal nanofluids, however, has been considered as a long-existing issue that limits their further development and practical application. This review overviews the recent efforts and progresses in improving the dispersion stability of thermal nanofluids such as mechanistic understanding of dispersion behavior of nanofluids, examples of both water-based and oil-based nanofluids, strategies to stabilize nanofluids, and characterization techniques for dispersion behavior of nanofluids. Finally, on-going research needs, and possible solutions to research challenges and future research directions in exploring stably dispersed thermal nanofluids are discussed. Keywords: Thermal nanofluids, Dispersion, Aggregation, Electrostatic stabilization, Steric stabilization

  10. Investigation of Thermal Stability of P2-NaxCoO2 Cathode Materials for Sodium Ion Batteries Using Real-Time Electron Microscopy.

    Science.gov (United States)

    Hwang, Sooyeon; Lee, Yongho; Jo, Eunmi; Chung, Kyung Yoon; Choi, Wonchang; Kim, Seung Min; Chang, Wonyoung

    2017-06-07

    Here, we take advantage of in situ transmission electron microscopy (TEM) to investigate the thermal stability of P2-type Na x CoO 2 cathode materials for sodium ion batteries, which are promising candidates for next-generation lithium ion batteries. A double-tilt TEM heating holder was used to directly characterize the changes in the morphology and the crystallographic and electronic structures of the materials with increase in temperature. The electron diffraction patterns and the electron energy loss spectra demonstrated the presence of cobalt oxides (Co 3 O 4 , CoO) and even metallic cobalt (Co) at higher temperatures as a result of reduction of Co ions and loss of oxygen. The bright-field TEM images revealed that the surface of Na x CoO 2 becomes porous at high temperatures. Higher cutoff voltages result in degrading thermal stability of Na x CoO 2 . The observations herein provide a valuable insight that thermal stability is one of the important factors to be considered in addition to the electrochemical properties when developing new electrode materials for novel battery systems.

  11. Power Electronics Thermal Management

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, Gilberto [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-08-07

    Thermal modeling was conducted to evaluate and develop thermal management strategies for high-temperature wide-bandgap (WBG)-based power electronics systems. WBG device temperatures of 175 degrees C to 250 degrees C were modeled under various under-hood temperature environments. Modeling result were used to identify the most effective capacitor cooling strategies under high device temperature conditions.

  12. Thermal stability and in situ SiN passivation of InAlN/GaN high electron mobility heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Lugani, L.; Carlin, J.-F.; Py, M. A.; Grandjean, N. [ICMP, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)

    2014-09-15

    We investigate the thermal stability of nearly lattice-matched InAlN layers under metal organic vapor phase epitaxy conditions for temperatures >800 °C and show that they are not fully stable. In particular, InAlN top layers undergo degradation during high temperature annealing due to a surface related process, which causes the loss of crystal quality. This strongly impacts the transport properties of InAlN/GaN HEMT heterostructures; in particular, the mobility is significantly reduced. However, we demonstrate that high thermal stability can be achieved by capping with a GaN layer as thin as 0.5 nm. Those findings enabled us to realize in situ passivated HEMT heterostructures with state of the art transport properties.

  13. Thermal stability of 4-substituted benzenediazonium tetrafluoroborates

    International Nuclear Information System (INIS)

    Bruner, V.Ya.

    1990-01-01

    Heating of tetraborates of 4-methyl-, 4-phenyl- and 4-dimethylaminobenzenediazonium at 95, 120 and 148 deg, correspondingly, causes their autocatalytic destruction, two moles of gas (nitrogen, boron fluoride) being liberated. The thermal stability of 4-substituted benzenediazonium tetrafluoroborates increases with the increase of the electron-donor activity of the substituent at benzene ring

  14. Investigating local degradation and thermal stability of charged nickel-based cathode materials through real-time electron microscopy.

    Science.gov (United States)

    Hwang, Sooyeon; Kim, Seung Min; Bak, Seong-Min; Cho, Byung-Won; Chung, Kyung Yoon; Lee, Jeong Yong; Chang, Wonyoung; Stach, Eric A

    2014-09-10

    In this work, we take advantage of in situ transmission electron microscopy (TEM) to investigate thermally induced decomposition of the surface of Li(x)Ni(0.8)Co(0.15)Al(0.05)O2 (NCA) cathode materials that have been subjected to different states of charge (SOC). While uncharged NCA is stable up to 400 °C, significant changes occur in charged NCA with increasing temperature. These include the development of surface porosity and changes in the oxygen K-edge electron energy loss spectra, with pre-edge peaks shifting to higher energy losses. These changes are closely related to O2 gas released from the structure, as well as to phase changes of NCA from the layered structure to the disordered spinel structure, and finally to the rock-salt structure. Although the temperatures where these changes initiate depend strongly on the state of charge, there also exist significant variations among particles with the same state of charge. Notably, when NCA is charged to x = 0.33 (the charge state that is the practical upper limit voltage in most applications), the surfaces of some particles undergo morphological and oxygen K-edge changes even at temperatures below 100 °C, a temperature that electronic devices containing lithium ion batteries (LIB) can possibly see during normal operation. Those particles that experience these changes are likely to be extremely unstable and may trigger thermal runaway at much lower temperatures than would be usually expected. These results demonstrate that in situ heating experiments are a unique tool not only to study the general thermal behavior of cathode materials but also to explore particle-to-particle variations, which are sometimes of critical importance in understanding the performance of the overall system.

  15. Thermal stability of titanate nanotubes

    Czech Academy of Sciences Publication Activity Database

    Králová, Daniela; Kužel, R.; Kovářová, Jana; Dybal, Jiří; Šlouf, Miroslav

    2009-01-01

    Roč. 16, 2a (2009), s. 41-43 ISSN 1211-5894. [Struktura - Colloquium of Czech and Slovak Crystallographic Association. Hluboká nad Vltavou, 22.06.2009-25.06.2009] R&D Projects: GA ČR GA203/07/0717; GA AV ČR KAN200520704 Institutional research plan: CEZ:AV0Z40500505 Keywords : titanate nanotubes * thermal stability Subject RIV: CD - Macromolecular Chemistry

  16. Chemical and thermal stability of insulin

    DEFF Research Database (Denmark)

    Huus, Kasper; Havelund, Svend; Olsen, Helle B

    2006-01-01

    To study the correlation between the thermal and chemical stability of insulin formulations with various insulin hexamer ligands.......To study the correlation between the thermal and chemical stability of insulin formulations with various insulin hexamer ligands....

  17. Thermal equilibrium, stability and burn control

    International Nuclear Information System (INIS)

    Cohn, D.

    1982-01-01

    A number of aspects of the thermal stability and equilibrium control of ignited tokamak plasma have been investigated. Examined approaches were passive control (the effect of radial motion, the effect of radial motion and small additional transport loss), active control (the compression and decompression of plasma, subignited operation with small amount of variable external heating, and density control), and thermal equilibrium control (additional power loss from impurity radiation and enhanced transport from increased ripple). One-D calculation has been made on thermal instability eigen-modes. It was found that for electron thermal induction loss given by Alcator scaling and for neoclassical ion transport, there was at most one unstable mode with a temperature profile which maintains the temperature profile at thermal equilibrium. The effect of the coupling of temperature fluctuation and the fluctuation in major radius was investigated. Temperature driven radial motion combined with a small amount of ripple transport loss was found to be a very effective mechanism for passive thermal stability control. (Kato, T.)

  18. Metalorganic chemical vapor deposition growth and thermal stability of the AlInN/GaN high electron mobility transistor structure

    International Nuclear Information System (INIS)

    Yu, Hongbo; Ozturk, Mustafa; Demirel, Pakize; Cakmak, Huseyin; Bolukbas, Basar; Caliskan, Deniz; Ozbay, Ekmel

    2011-01-01

    The Al x In 1−x N barrier high electron mobility transistor (HEMT) structure has been optimized with varied barrier composition and thickness grown by metalorganic chemical vapor deposition. After optimization, a transistor structure comprising a 7 nm thick nearly lattice-matched Al 0.83 In 0.17 N barrier exhibits a sheet electron density of 2.0 × 10 13 cm −2 with a high electron mobility of 1540 cm 2 V −1 s −1 . An Al 0.83 In 0.17 N barrier HEMT device with 1 µm gate length provides a current density of 1.0 A mm −1 at V GS = 0 V and an extrinsic transconductance of 242 mS mm −1 , which are remarkably improved compared to that of a conventional Al 0.3 Ga 0.7 N barrier HEMT. To investigate the thermal stability of the HEMT epi-structures, post-growth annealing experiments up to 800 °C have been applied to Al 0.83 In 0.17 N and Al 0.3 Ga 0.7 N barrier heterostructures. As expected, the electrical properties of an Al 0.83 In 0.17 N barrier HEMT structure showed less stability than that of an Al 0.3 Ga 0.7 N barrier HEMT to the thermal annealing. The structural properties of Al 0.83 In 0.17 N/GaN also showed more evidence for decomposition than that of the Al 0.3 Ga 0.7 N/GaN structure after 800 °C post-annealing

  19. Synthesis, Spectral Characterization, Electron Microscopic Study and Influence on the Thermal Stability of Phosphorus-containing Dendrimer with a 4,4'-Sulphonyldiphenol at the Core

    International Nuclear Information System (INIS)

    Dadapeer, Echchukattula; Rasheed, Syed; Raju, Chamarthi Naga

    2011-01-01

    The divergent synthesis of novel phosphorus-containing dendrimer with 4,4'-sulphonyldiphenol at the core has been accomplished involving simple condensation reactions using P(O)Cl 3 , P(S)Cl 3 , 3-amino-phenol, 3-hydroxy-benzaldehyde, and 2-butyn 1, 4-diol. The final compound was a Schiff's base macromolecule possessing 4 imine bonds, 8 acetylenic bonds and 8 OH groups at the periphery. The structures of intermediate compounds were confirmed by IR, NMR ( 1 H, 13 C and 31 P), LC-Mass and C, H, N analysis. The structure of the final dendrimer was confirmed by IR, NMR ( 1 H, 13 C and 31 P), MALDI-TOF-MS, and C, H, N analysis. The surface morphological characteristics of the final dendrimer were understood by Scanning Electronic Microscopic study (SEM). The thermal stability of the final dendrimer was studied by TGA/DTA analysis

  20. Spatial Atmospheric Pressure Atomic Layer Deposition of Tin Oxide as an Impermeable Electron Extraction Layer for Perovskite Solar Cells with Enhanced Thermal Stability.

    Science.gov (United States)

    Hoffmann, Lukas; Brinkmann, Kai O; Malerczyk, Jessica; Rogalla, Detlef; Becker, Tim; Theirich, Detlef; Shutsko, Ivan; Görrn, Patrick; Riedl, Thomas

    2018-02-14

    Despite the notable success of hybrid halide perovskite-based solar cells, their long-term stability is still a key-issue. Aside from optimizing the photoactive perovskite, the cell design states a powerful lever to improve stability under various stress conditions. Dedicated electrically conductive diffusion barriers inside the cell stack, that counteract the ingress of moisture and prevent the migration of corrosive halogen species, can substantially improve ambient and thermal stability. Although atomic layer deposition (ALD) is excellently suited to prepare such functional layers, ALD suffers from the requirement of vacuum and only allows for a very limited throughput. Here, we demonstrate for the first time spatial ALD-grown SnO x at atmospheric pressure as impermeable electron extraction layers for perovskite solar cells. We achieve optical transmittance and electrical conductivity similar to those in SnO x grown by conventional vacuum-based ALD. A low deposition temperature of 80 °C and a high substrate speed of 2.4 m min -1 yield SnO x layers with a low water vapor transmission rate of ∼10 -4 gm -2 day -1 (at 60 °C/60% RH). Thereby, in perovskite solar cells, dense hybrid Al:ZnO/SnO x electron extraction layers are created that are the key for stable cell characteristics beyond 1000 h in ambient air and over 3000 h at 60 °C. Most notably, our work of introducing spatial ALD at atmospheric pressure paves the way to the future roll-to-roll manufacturing of stable perovskite solar cells.

  1. Understanding the Thermal Stability of Palladium-Platinum Core-Shell Nanocrystals by In Situ Transmission Electron Microscopy and Density Functional Theory.

    Science.gov (United States)

    Vara, Madeline; Roling, Luke T; Wang, Xue; Elnabawy, Ahmed O; Hood, Zachary D; Chi, Miaofang; Mavrikakis, Manos; Xia, Younan

    2017-05-23

    Core-shell nanocrystals offer many advantages for heterogeneous catalysis, including precise control over both the surface structure and composition, as well as reduction in loading for rare and costly metals. Although many catalytic processes are operated at elevated temperatures, the adverse impacts of heating on the shape and structure of core-shell nanocrystals are yet to be understood. In this work, we used ex situ heating experiments to demonstrate that Pd@Pt 4L core-shell nanoscale cubes and octahedra are promising for catalytic applications at temperatures up to 400 °C. We also used in situ transmission electron microscopy to monitor the thermal stability of the core-shell nanocrystals in real time. Our results demonstrate a facet dependence for the thermal stability in terms of shape and composition. Specifically, the cubes enclosed by {100} facets readily deform shape at a temperature 300 °C lower than that of the octahedral counterparts enclosed by {111} facets. A reversed trend is observed for composition, as alloying between the Pd core and the Pt shell of an octahedron occurs at a temperature 200 °C lower than that for the cubic counterpart. Density functional theory calculations provide atomic-level explanations for the experimentally observed behaviors, demonstrating that the barriers for edge reconstruction determine the relative ease of shape deformation for cubes compared to octahedra. The opposite trend for alloying of the core-shell structure can be attributed to a higher propensity for subsurface Pt vacancy formation in octahedra than in cubes.

  2. Thermal stability of ultrasoft Fe-Zr-N films

    NARCIS (Netherlands)

    Chechenin, NG; van Veen, A; Schut, H; Chezan, AR; Boerma, D; Vystavel, T; De Hosson, JTM

    2003-01-01

    The thermal stability of nanocrystalline ultrasoft magnetic (Fe98Zr2)(1-x)N-x films with x = 0.10-0.25 was studied using thermal desorption spectrometry, positron beam analysis and high resolution transmission electron microscopy. The results demonstrate that grain growth during the heat treatment

  3. A polymorphic variant in the human electron transfer flavoprotein alpha-chain (alpha-T171) displays decreased thermal stability and is overrepresented in very-long-chain acyl-CoA dehydrogenase-deficient patients with mild childhood presentation

    DEFF Research Database (Denmark)

    Bross, P; Pedersen, P; Nyholm, M

    1999-01-01

    The consequences of two amino acid polymorphisms of human electron transfer flavoprotein (alpha-T/I171 in the alpha-subunit and beta-M/T154 in the beta-subunit) on the thermal stability of the enzyme are described. The alpha-T171 variant displayed a significantly decreased thermal stability, wher....... This is compatible with a negative modulating effect of the less-stable alpha-T171 ETF variant in this group of VLCAD patients that harbor missense mutations in at least one allele and therefore potentially display residual levels of VLCAD enzyme activity. Udgivelsesdato: 1999-Jun...

  4. A study of mini-channel thermal module design for achieving high stability and high capability in electronic cooling

    International Nuclear Information System (INIS)

    Wang, Hsiang-Li; Wu, Huang-Ching; Kong Wang, S.; Hung, Tzu-Chen; Yang, Ruey-Jen

    2013-01-01

    In this study, pressure drop and heat transfer characteristics of multiple-mini-channel thermal modules were investigated quantitatively. The flow channels, which were mounted on one side of a copper test section, were designed in three types: (1) the first module consists of fourteen straight and parallel channels with a rectangular cross section of 1 mm × 3 mm, (2) the second module consists of fourteen gradually widening channels with a U-shaped cross section starting from an inlet section of 0.5 mm × 3 mm and increasing to an outlet section of 1 mm × 3 mm, and (3) the third module is similar to the second module except for the rectangular cross section. Visual observations and the measured boiling curves show that, in the straight channels, some bubbles cannot be flushed out of the channels fast enough, so they tend to flow back and accumulate at the entrance. This results in a rather dry channel condition for CHF (critical heat flux) to occur for the cases with low flow rates. For the widening channel modules, no occurrence of CHF was observed under an even lower operating pressure in an attempt to induce the incipient of CHF. Under a similar temperature rise at the channel exit, the maximum heat removal rate of the widening channels reaches 27 W/cm 2 which is at least twice as high as that of the straight channels. -- Highlights: ► Three mini-channel modules were designed, and experiments were carried out on pressure drop and heat transfer characteristics. ► Comparisons were made between one regular straight-channel module and two widening-channel modules with rectangular and U-shaped cross sections. ► It was found that the widening channels yield a stable two-phase heat transfer mode with no occurrence of CHF due to a better movement of the bubbles and the absence of backflow which causes accumulation of bubbles commonly occur at the entrance of the straight-shaped parallel channels. ► The maximum heat removal rate of the widening channels reaches

  5. Enhancement of the solubility, thermal stability, and electronic properties of carbon nanotubes functionalized with MEH-PPV: A combined experimental and computational study

    International Nuclear Information System (INIS)

    Prajongtat, P.; Suramitr, S.; Hannongbua, S.; Gleeson, M.P.; Mitsuke, K.

    2013-01-01

    Multi-walled carbon nanotubes (MWCNTs) functionalized with poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene] (MWCNT-f-MEH-PPV) nanocomposites were successfully prepared by employing a “grafting from” approach. The content of the functionalizing MEH-PPV in the composites was observed as 76 wt.%. Compared with pristine MWCNTs (p-MWCNT), the aqueous solubility and thermal stability of the former are significantly enhanced. The effect of covalently and non-covalently functionalized nanotubes on dye-sensitized solar cell performance was also studied. Solar cells were successfully fabricated from isolated MEH-PPV, p-MWCNT/MEH-PPV, and MWCNT-f-MEH-PPV/MEH-PPV counter electrodes. The devices based on a MWCNT-f-MEH-PPV/MEH-PPV counter electrode demonstrated the best photovoltaic performance as observed by higher J SC, V OC, and fill factor (FF) values. The experimental phenomena can be explained by quantum-chemical calculations: Charge transfer from MEH-PPV oligomers to nanotubes is greater when covalently functionalized compared with non-covalently functionalized. This suggests that the improvement in the photovoltaic parameters of the cells containing covalently functionalized nanotubes results not only from the higher concentration present in the nanotube films of the counter electrode, but also from the greater electron delocalization between the oligomers and nanotubes. (author)

  6. Synthesis, Spectral Characterization, Electron Microscopic Study and Influence on the Thermal Stability of Phosphorus-containing Dendrimer with a 4,4'-Sulphonyldiphenol at the Core

    Energy Technology Data Exchange (ETDEWEB)

    Dadapeer, Echchukattula; Rasheed, Syed; Raju, Chamarthi Naga [Sri Venkateswara University, Tirupat (India)

    2011-02-15

    The divergent synthesis of novel phosphorus-containing dendrimer with 4,4'-sulphonyldiphenol at the core has been accomplished involving simple condensation reactions using P(O)Cl{sub 3}, P(S)Cl{sub 3}, 3-amino-phenol, 3-hydroxy-benzaldehyde, and 2-butyn 1, 4-diol. The final compound was a Schiff's base macromolecule possessing 4 imine bonds, 8 acetylenic bonds and 8 OH groups at the periphery. The structures of intermediate compounds were confirmed by IR, NMR ({sup 1}H, {sup 13}C and {sup 31}P), LC-Mass and C, H, N analysis. The structure of the final dendrimer was confirmed by IR, NMR ({sup 1}H, {sup 13}C and {sup 31}P), MALDI-TOF-MS, and C, H, N analysis. The surface morphological characteristics of the final dendrimer were understood by Scanning Electronic Microscopic study (SEM). The thermal stability of the final dendrimer was studied by TGA/DTA analysis.

  7. System design description PFP thermal stabilization

    International Nuclear Information System (INIS)

    RISENMAY, H.R.

    1998-01-01

    The purpose of this document is to provide a system design description and design basis for the Plutonium Finishing P1ant (PFP) Thermal Stabilization project. The sources of material for this project are residues scraped from glovebox floors and materials already stored in vault storage that need further stabilizing to meet the 3013 storage requirements. Stabilizing this material will promote long term storage and reduced worker exposure. This document addresses: function design, equipment, and safety requirements for thermal stabilization of plutonium residues and oxides

  8. Power Electronics Thermal Management | Transportation Research | NREL

    Science.gov (United States)

    Power Electronics Thermal Management Power Electronics Thermal Management A photo of water boiling in liquid cooling lab equipment. Power electronics thermal management research aims to help lower the investigates and develops thermal management strategies for power electronics systems that use wide-bandgap

  9. Aging effects on vertical graphene nanosheets and their thermal stability

    Science.gov (United States)

    Ghosh, S.; Polaki, S. R.; Ajikumar, P. K.; Krishna, N. G.; Kamruddin, M.

    2018-03-01

    The present study investigates environmental aging effects and thermal stability of vertical graphene nanosheets (VGN). Self-organized VGN is synthesized by plasma enhanced chemical vapor deposition and exposed to ambient conditions over 6-month period to examine its aging behavior. A systematic inspection is carried out on morphology, chemical structure, wettability and electrical property by scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, water contact angle and four-probe resistivity measurements at regular intervals, respectively. Detailed microscopic and spectroscopic analysis substantiated the retention of graphitic quality and surface chemistry of VGN over the test period. An unchanged sheet resistance and hydrophobicity reveals its electrical and wetting stability over the time, respectively. Thermogravimetric analysis ensures an excellent thermal stability of VGN up to 575 °C in ambient atmosphere. These findings of long-term morphological, structural, wetting, electrical and thermal stability of VGN validate their potential utilization for the next-generation device applications.

  10. Hardness and thermal stability of cubic silicon nitride

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Kragh, Flemming; Frost, D. J.

    2001-01-01

    The hardness and thermal stability of cubic spinel silicon nitride (c-Si3N4), synthesized under high-pressure and high-temperature conditions, have been studied by microindentation measurements, and x-ray powder diffraction and scanning electron microscopy, respectively The phase at ambient...

  11. Thermal Stabilization of Biologics with Photoresponsive Hydrogels.

    Science.gov (United States)

    Sridhar, Balaji V; Janczy, John R; Hatlevik, Øyvind; Wolfson, Gabriel; Anseth, Kristi S; Tibbitt, Mark W

    2018-03-12

    Modern medicine, biological research, and clinical diagnostics depend on the reliable supply and storage of complex biomolecules. However, biomolecules are inherently susceptible to thermal stress and the global distribution of value-added biologics, including vaccines, biotherapeutics, and Research Use Only (RUO) proteins, requires an integrated cold chain from point of manufacture to point of use. To mitigate reliance on the cold chain, formulations have been engineered to protect biologics from thermal stress, including materials-based strategies that impart thermal stability via direct encapsulation of the molecule. While direct encapsulation has demonstrated pronounced stabilization of proteins and complex biological fluids, no solution offers thermal stability while enabling facile and on-demand release from the encapsulating material, a critical feature for broad use. Here we show that direct encapsulation within synthetic, photoresponsive hydrogels protected biologics from thermal stress and afforded user-defined release at the point of use. The poly(ethylene glycol) (PEG)-based hydrogel was formed via a bioorthogonal, click reaction in the presence of biologics without impact on biologic activity. Cleavage of the installed photolabile moiety enabled subsequent dissolution of the network with light and release of the encapsulated biologic. Hydrogel encapsulation improved stability for encapsulated enzymes commonly used in molecular biology (β-galactosidase, alkaline phosphatase, and T4 DNA ligase) following thermal stress. β-galactosidase and alkaline phosphatase were stabilized for 4 weeks at temperatures up to 60 °C, and for 60 min at 85 °C for alkaline phosphatase. T4 DNA ligase, which loses activity rapidly at moderately elevated temperatures, was protected during thermal stress of 40 °C for 24 h and 60 °C for 30 min. These data demonstrate a general method to employ reversible polymer networks as robust excipients for thermal stability of complex

  12. Enhancing the thermal stability of natural rubber/recycled ethylene–propylene–diene rubber blends by means of introducing pre-vulcanised ethylene–propylene–diene rubber and electron beam irradiation

    International Nuclear Information System (INIS)

    Nabil, H.; Ismail, H.

    2014-01-01

    Highlights: • New route of processing was introduced to optimise the thermal stability of NR/R-EPDM blends. • Pre-vulcanised EPDM and EB irradiation were introduced into NR/R-EPDM blends. • Thermal stability is obviously enhanced by applying these two techniques. • Applying new route of processing methods is clearly successful to NR/R-EPDM blends. - Abstract: Most rubber materials are subjected to oxidation. The rate of oxidation depends on the type of rubber, processing method, and end-use conditions. The oxidation of rubber can result in the loss of physical properties, such as tensile strength, elongation, and flexibility. Hence, the service life is determined by oxidation stability. Thermal properties are relevant to the potential use of polymeric materials in many consumer oriented applications. Thermo-oxidative ageing and thermogravimetric analysis (TGA) have been proven to be successful techniques in determining the thermal stability of polymers and polymer blends. In this article, preparation of a series of natural rubber/recycled ethylene–propylene–diene rubber (NR/R-EPDM) blends is described. Processing of the blends, by means of introducing pre-vulcanised EPDM and electron beam (EB) irradiation, was carried out. Two thermal analysis methods, namely thermo-oxidative ageing and thermogravimetric analysis, were conducted. The results indicated that pre-vulcanising EPDM for 1.45 min (ts − 2) is sufficient to gain the optimum retained tensile and elongation at break. It was simultaneously observed that the introduction of pre-vulcanised EPDM increased decomposition temperature and activation energy by showing optimum values at a pre-vulcanising time of 3.45 min (ts). In the latter study, the retained properties increased after EB irradiation. The results can be verified by the thermal decomposition temperature and their activation energy. The obtained TG profiles and the calculated kinetic parameters indicated that introducing EB irradiation

  13. Research of thermal stability of ion exchangers

    International Nuclear Information System (INIS)

    Stuchlik, S.; Srnkova, J.

    1983-01-01

    Prior to the fixation of radioactive ion exchangers into bitumen these exchangers have to be dried. The resulting gaseous products may generate explosive mixtures. An analysis was made of the thermal stability of two types of ion exchangers, the cation exchanger KU-2-8 cS and the anion exchanger AV-17-8 cS which are used in the V-1 nuclear power plant at Jaslovske Bohunice. The thermal stability of the anion exchangers was monitored using gas chromatography at temperatures of 100, 120, 140, 160 and 180 degC and by measuring weight loss by kiln-drying at temperatures of 120, 140, 160 and 180 degC. The ion exchanger was heated for 6 hours and samples were taken continuously at one hour intervals. The thermal stability of the cation exchanger was monitored by measuring the weight loss. Gas chromatography showed the release of trimethylamine from the anion exchanger in direct dependence on temperature. The measurement of weight losses, however, only showed higher losses of released products which are explained by the release of other thermally unstable products. The analysis of the thermal stability of the cation exchanger showed the release of SO 2 and the weight loss (following correction for water content) was found only after the fourth hour of decomposition. The experiment showed that the drying of anion exchanger AV-17-8 cS may cause the formation of explosive mixtures. (J.P.)

  14. Thermal stability engineering of Glomerella cingulata cutinase.

    Science.gov (United States)

    Chin, Iuan-Sheau; Abdul Murad, Abdul Munir; Mahadi, Nor Muhammad; Nathan, Sheila; Abu Bakar, Farah Diba

    2013-05-01

    Cutinase has been ascertained as a biocatalyst for biotechnological and industrial bioprocesses. The Glomerella cingulata cutinase was genetically modified to enhance its enzymatic performance to fulfill industrial requirements. Two sites were selected for mutagenesis with the aim of altering the surface electrostatics as well as removing a potentially deamidation-prone asparagine residue. The N177D cutinase variant was affirmed to be more resilient to temperature increase with a 2.7-fold increase in half-life at 50°C as compared with wild-type enzyme, while, the activity at 25°C is not compromised. Furthermore, the increase in thermal tolerance of this variant is accompanied by an increase in optimal temperature. Another variant, the L172K, however, exhibited higher enzymatic performance towards phenyl ester substrates of longer carbon chain length, yet its thermal stability is inversely affected. In order to restore the thermal stability of L172K, we constructed a L172K/N177D double variant and showed that these two mutations yield an improved variant with enhanced activity towards phenyl ester substrates and enhanced thermal stability. Taken together, our study may provide valuable information for enhancing catalytic performance and thermal stability in future engineering endeavors.

  15. Studies on thermal properties and thermal control effectiveness of a new shape-stabilized phase change material with high thermal conductivity

    International Nuclear Information System (INIS)

    Cheng Wenlong; Liu Na; Wu Wanfan

    2012-01-01

    In order to overcome the difficulty of conventional phase change materials (PCMs) in packaging, the shape-stabilized PCMs are proposed to be used in the electronic device thermal control. However, the conventional shape-stabilized PCMs have the drawback of lower thermal conductivity, so a new shape-stabilized PCM with high thermal conductivity, which is suitable for thermal control of electronic devices, is prepared. The thermal properties of n-octadecane-based shape-stabilized PCM are tested and analyzed. The heat storage/release performance is studied by numerical simulation. Its thermal control effect for electronic devices is also discussed. The results show that the expanded graphite (EG) can greatly improve the thermal conductivity of the material with little effect on latent heat and phase change temperature. When the mass fraction of EG is 5%, thermal conductivity has reached 1.76 W/(m K), which is over 4 times than that of the original one. Moreover, the material has larger latent heat and good thermal stability. The simulation results show that the material can have good heat storage/release performance. The analysis of the effect of thermal parameters on thermal control effect for electronic devices provides references to the design of phase change thermal control unit. - Highlights: ► A new shape-stabilized PCM with higher thermal conductivity is prepared. ► The material overcomes the packaging difficulty of traditional PCMs used in thermal control unit. ► The EG greatly improves thermal conductivity with little effect on latent heat. ► The material has high thermal stability and good heat storage/release performance. ► The effectiveness of the material for electronic device thermal control is proved.

  16. Interacting dark energy model and thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Bhandari, Pritikana; Haldar, Sourav; Chakraborty, Subenoy [Jadavpur University, Department of Mathematics, Kolkata, West Bengal (India)

    2017-12-15

    In the background of the homogeneous and isotropic FLRW model, the thermodynamics of the interacting DE fluid is investigated in the present work. By studying the thermodynamical parameters, namely the heat capacities and the compressibilities, both thermal and mechanical stability are discussed and the restrictions on the equation of state parameter of the dark fluid are analyzed. (orig.)

  17. Interacting dark energy model and thermal stability

    International Nuclear Information System (INIS)

    Bhandari, Pritikana; Haldar, Sourav; Chakraborty, Subenoy

    2017-01-01

    In the background of the homogeneous and isotropic FLRW model, the thermodynamics of the interacting DE fluid is investigated in the present work. By studying the thermodynamical parameters, namely the heat capacities and the compressibilities, both thermal and mechanical stability are discussed and the restrictions on the equation of state parameter of the dark fluid are analyzed. (orig.)

  18. Thermal stability of PMMA–clay hybrids

    Indian Academy of Sciences (India)

    Administrator

    Thermal stability of PMMA–clay hybrids. TANUSHREE CHOUDHURY* and NIRENDRA M MISRA. Department of Applied Chemistry, Indian School of Mines University, Dhanbad 826 004, India. MS received 9 December 2008. Abstract. Materials with small particle size are being extensively used in composites and hybrid ...

  19. Structure and thermal stability of nanocrystalline materials

    Indian Academy of Sciences (India)

    In addition, study of the thermal stability of nanocrystalline materials against significant grain growth is both scientific and technological interest. A sharp increase in grain size (to micron levels) during consolidation of nanocrystalline powders to obtain fully dense materials may consequently result in the loss of some unique ...

  20. Transient Thermal Stability of Polymer Nanocomposites

    Science.gov (United States)

    2012-08-01

    modified Montmorillonite, Nanocor masterbatch ) 1 wt % carbon black (Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2·nH2O Multiwalled Carbon Nanotubes (Nanocyl... masterbatch ) Twin screw extrusion (190C) Slow Heating Regime Thermogravimetric Analysis Nanospecies improve thermal stability as expected Laser

  1. Thermal Transport in Diamond Films for Electronics Thermal Management

    Science.gov (United States)

    2018-03-01

    AFRL-RY-WP-TR-2017-0219 THERMAL TRANSPORT IN DIAMOND FILMS FOR ELECTRONICS THERMAL MANAGEMENT Samuel Graham Georgia Institute of Technology MARCH... ELECTRONICS THERMAL MANAGEMENT 5a. CONTRACT NUMBER FA8650-15-C-7517 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 61101E 6. AUTHOR(S) Samuel...seeded sample (NRL 010516, Die A5). The NCD membrane and Al layer thicknesses, tNCD, were measured via transmission electron microscopy (TEM). The

  2. Evaluation of electron beam stabilization for ion implant processing

    Science.gov (United States)

    Buffat, Stephen J.; Kickel, Bee; Philipps, B.; Adams, J.; Ross, Matthew F.; Minter, Jason P.; Marlowe, Trey; Wong, Selmer S.

    1999-06-01

    With the integration of high energy ion implant processes into volume CMOS manufacturing, the need for thick resist stabilization to achieve a stable ion implant process is critical. With new photoresist characteristics, new implant end station characteristics arise. The resist outgassing needs to be addressed as well as the implant profile to ensure that the dosage is correct and the implant angle does not interfere with other underlying features. This study compares conventional deep-UV/thermal with electron beam stabilization. The electron beam system used in this study utilizes a flood electron source and is a non-thermal process. These stabilization techniques are applied to a MeV ion implant process in a CMOS production process flow.

  3. Thermal Stabilization FY 1999 blend plan

    Energy Technology Data Exchange (ETDEWEB)

    RISENMAY, H.R.

    1999-02-23

    This Blend Plan documents the alternate feed material items for the thermal stabilization process that will be used in place of the metal items that were originally planned to be processed. Problems with resolution of the safety basis for the metal items resulted in the decision to run material that already had an established safety basis. Various in process and scrap recovery items stored in gloveboxes, plutonium oxide and plutonium oxide mixed with uranium oxide stored in 2736-Z vaults will be processed through the stabilization furnaces until the safety basis for the metal items has been resolved. The purpose of thermal stabilization is to heat the material to 1000 degrees Celsius to drive off all volatile materials and leave the plutonium and/or uranium as oxides. The stabilized material will be sampled to determine the Loss On Ignition (LOI). The stabilized material must meet LOI of less than 0.5% to be acceptable for storage under DOE-STD-3013-94 specifications. Out of specification material will be recycled through the furnaces until the LOI limits are met.

  4. Thermal Stabilization FY 1999 blend plan

    International Nuclear Information System (INIS)

    RISENMAY, H.R.

    1999-01-01

    This Blend Plan documents the alternate feed material items for the thermal stabilization process that will be used in place of the metal items that were originally planned to be processed. Problems with resolution of the safety basis for the metal items resulted in the decision to run material that already had an established safety basis. Various in process and scrap recovery items stored in gloveboxes, plutonium oxide and plutonium oxide mixed with uranium oxide stored in 2736-Z vaults will be processed through the stabilization furnaces until the safety basis for the metal items has been resolved. The purpose of thermal stabilization is to heat the material to 1000 degrees Celsius to drive off all volatile materials and leave the plutonium and/or uranium as oxides. The stabilized material will be sampled to determine the Loss On Ignition (LOI). The stabilized material must meet LOI of less than 0.5% to be acceptable for storage under DOE-STD-3013-94 specifications. Out of specification material will be recycled through the furnaces until the LOI limits are met

  5. Thermal stabilization FY 1999 blend plan

    International Nuclear Information System (INIS)

    RISENMAY, H.R.

    1999-01-01

    This Blend Plan documents the alternate feed material items for the thermal stabilization process that will be used in place of the metal items that were originally planned to be processed. Problems with resolution of the safety basis for the metal items resulted in the decision to run material that already had an established safety basis. Various in process and scrap recovery items stored in gloveboxes, plutonium oxide and plutonium oxide mixed with uranium oxide stored in 2736-2 vaults will be processed through the stabilization furnaces until the safety basis for the metal items has been resolved. The purpose of thermal stabilization is to heat the material to 1000 degrees Celsius to drive off all volatile materials and leave the plutonium and/or uranium as oxides. The stabilized material will be sampled to determine the Loss On Ignition (LOI). The stabilized material must meet LOI of less than 0.5% to be acceptable for storage under DOE-STD-3013-94 specifications. Out of specification material will be recycled through the furnaces until the LOI limits are met

  6. Thermal stabilization FY 1999 blend plan

    Energy Technology Data Exchange (ETDEWEB)

    RISENMAY, H.R.

    1999-06-01

    This Blend Plan documents the alternate feed material items for the thermal stabilization process that will be used in place of the metal items that were originally planned to be processed. Problems with resolution of the safety basis for the metal items resulted in the decision to run material that already had an established safety basis. Various in process and scrap recovery items stored in gloveboxes, plutonium oxide and plutonium oxide mixed with uranium oxide stored in 2736-2 vaults will be processed through the stabilization furnaces until the safety basis for the metal items has been resolved. The purpose of thermal stabilization is to heat the material to 1000 degrees Celsius to drive off all volatile materials and leave the plutonium and/or uranium as oxides. The stabilized material will be sampled to determine the Loss On Ignition (LOI). The stabilized material must meet LOI of less than 0.5% to be acceptable for storage under DOE-STD-3013-94 specifications. Out of specification material will be recycled through the furnaces until the LOI limits are met.

  7. Thermal stability of tunneling spin polarization

    International Nuclear Information System (INIS)

    Kant, C.H.; Kohlhepp, J.T.; Paluskar, P.V.; Swagten, H.J.M.; Jonge, W.J.M. de

    2005-01-01

    We present a study of the thermal stability of tunneling spin polarization in Al/AlOx/ferromagnet junctions based on the spin-polarized tunneling technique, in which the Zeeman-split superconducting density of states in the Al electrode is used as a detector for the spin polarization. Thermal robustness of the polarization, which is of key importance for the performance of magnetic tunnel junction devices, is demonstrated for post-deposition anneal temperatures up to 500 o C with Co and Co 90 Fe 10 top electrodes, independent of the presence of an FeMn layer on top of the ferromagnet

  8. System Design Description PFP Thermal Stabilization

    International Nuclear Information System (INIS)

    RISENMAY, H.R.

    2000-01-01

    The purpose of this document is to provide a system design description (SDD) and design basis for the Plutonium Finishing Plant (PFP) Thermal Stabilization project. The chief objective of the SDD is to document the Structures, Systems, and Components (SSCs) that establish and maintain the facility Safety Envelope necessary for normal safe operation of the facility; as identified in the FSAR, the OSRs, and Safety Assessment Documents (SADs). This safety equipment documentation should satisfy guidelines for the SDD given in WHC-SD-CP-TI-18 1, Criteria for Identification and Control of Equipment Necessary for Preservation of the Safety Envelope and Safe Operation of PFP. The basis for operational, alarm response, maintenance, and surveillance procedures are also identified and justified in this document. This document and its appendices address the following elements of the PFP Thermal Stabilization project: Functional and design requirements; Design description; Safety Envelope Analysis; Safety Equipment Class; and Operational, maintenance and surveillance procedures

  9. Jet Fuel Thermal Stability Investigations Using Ellipsometry

    Science.gov (United States)

    Nash, Leigh; Vasu, Subith S.; Klettlinger, Jennifer Lindsey

    2017-01-01

    Jet fuels are typically used for endothermic cooling in practical engines where their thermal stability is very important. In this work the thermal stability of Sasol IPK (a synthetic jet fuel) with varying levels of naphthalene has been studied on stainless steel substrates using spectroscopic ellipsometry in the temperature range 385-400 K. Ellipsometry is an optical technique that measures the changes in a light beam’s polarization and intensity after it reflects off of a thin film to determine the film’s thickness and optical properties. All of the tubes used were rated as thermally unstable by the color standard portion of the Jet Fuel Thermal Oxidation Test, and this was confirmed by the deposit thicknesses observed using ellipsometry. A new amorphous model on a stainless steel substrate was used to model the data and obtain the results. It was observed that, as would be expected, increasing the temperature of the tube increased the overall deposit amount for a constant concentration of naphthalene. The repeatability of these measurements was assessed using multiple trials of the same fuel at 385 K. Lastly, the effect of increasing the naphthalene concentration in the fuel at a constant temperature was found to increase the deposit thickness.In conclusion, ellipsometry was used to investigate the thermal stability of jet fuels on stainless steel substrate. The effects of increasing temperature and addition of naphthalene on stainless steel tubes with Sasol IPK fuel were investigated. It was found, as expected, that increasing temperature lead to an increase in deposit thickness. It wasAmerican Institute of Aeronautics and Astronautics6also found that increasing amounts of naphthalene increased the maximum deposit thickness. The repeatability of these measurements was investigated using multiple tests at the same conditions. The present work provides as a better quantitative tool compared to the widely used JFTOT technique. Future work will expand on the

  10. Thermal propagation and stability in superconducting films

    International Nuclear Information System (INIS)

    Gray, K.E.; Kampwirth, R.T.; Zasadzinski, J.F.; Ducharme, S.P.

    1983-01-01

    Thermal propagation and stable hot spots (normal domains) are studied in various high Tsub(c) superconducting films (Nb 3 Sn, Nb, NbN and Nb 3 Ge). A new energy balance is shown to give reasonable quantitative agreement of the dependence of the propagation velocity on the length of short normal domains. The steady state (zero velocity) measurements indicate the existence of two distinct situations for films on high thermal conductivity (sapphire) substrates. For low power per unit area the film and substrate have the same temperature, and the thermal properties of the substrate dominate. However, for higher power densities in short hot spots, the coupling is relatively weak and the thermal properties of the film alone are important. Here a connection is made between the critical current stability of superconducting films and a critical hot spot size for thermal propagation. As a result efficient heat removal is shown to dominate the stabilisation of superconducting films. The strong and weak coupling situations also lead to modifications of the models for propagation velocities on sapphire substrates. Self-healing of hot spots and other phenomena in superconducting film are explained. The potential use of the thermal propagation model in applications of superconductors, especially switches is discussed. (author)

  11. Stability of thermal HFB and dissipative thermal RPA

    CERN Document Server

    Tanabe, K

    1999-01-01

    It is shown that, as for a Nilsson + pairing model, the extended stability condition of the thermal Hartree-Fock-Bogoliubov (THFB) solution coincides with the one of the thermal RPA (TRPA) solution unless the pairing constant G is too large. As possible extensions of the TRPA equation in alternative ways describing thermal fluctuation effect, the extended TRPA (ETRPA) and the dissipative TRPA (DTRPA) are discussed. Furthermore, the general microscopic framework of the TRPA predicts the saturation and decrease of giant resonance width in high temperature limit, i.e. the fragmentation width GAMMA sub f propor to(kT) sup ( sup - sup 3 sup ( sup 2 sup ) sup ) and the spreading width GAMMA suparrow down propor to(kT) sup ( sup - sup 1 sup ( sup 2 sup ) sup ).

  12. Thermal stability of radiation vulcanized EPDM rubber

    International Nuclear Information System (INIS)

    Abdel-Aziz, M.M.

    2005-01-01

    Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) have been used to study the thermal stability of gamma- ray vulcanized ethylene-propylene diene rubber (EPDM) stabilized with various types of antioxidants. The antioxidants used were penta erythrityl tetrakis(3,5- di-tert-butyl(-4-hydroxyphenyl)propionate (Irganox 1010), Irganox 1035, Irganox 1520 D, as primary antioxidants; Irganox B 561 and Irganox B 900, as synergistic blends; hindered amine light stabilizer (HALS), i.e. Tinuvin 622 LD; N-isopropyl-N-phenyl-p-phenylene diamine (IPPD) and Trimethyl quinoline (TMQ) and their mixtures. The measurements were carried out under atmospheric conditions. The effect of antioxidant type, selected concentration and mechanism of reaction were determined

  13. Thermal Stability of Li-Ion Cells

    International Nuclear Information System (INIS)

    ROTH, EMANUEL P.

    1999-01-01

    The thermal stability of Li-ion cells with intercalating carbon anodes and metal oxide cathodes was measured as a function of state of charge and temperature for two advanced cell chemistries. Cells of the 18650 design with Li(sub x)CoO(sub 2) cathodes (commercial SONY cells) and Li(sub x)Ni(sub 0.8)Co(sub 0.2)O(sub 2) cathodes were measured for thermal reactivity in the open circuit cell condition. Accelerating rate calorimetry (ARC) was used to measure cell thermal runaway as a function of state of charge (SOC). Microcalorimetry was used to measure the time dependence of heat generating side reactions also as a function of SOC. Components of cells were measured using differential scanning calorimetry (DSC) to study the thermal reactivity of the individual electrodes to determine the temperature regimes and conditions of the major thermal reactions. Thermal decomposition of the SEI layer at the anodes was identified as the initiating source for thermal runaway. The cells with Li(sub x)CoO(sub 2) cathodes showed greater sensitivity to SOC and higher accelerating heating rates than seen for the cells with Li(sub x)Ni(sub 0.8)Co(sub 0.2)O(sub 2)cathodes. Lower temperature reactions starting as low as 40 C were also observed that were SOC dependent but not accelerating. These reactions were also measured in the microcalorimeter and observed to decay over time with a power-law dependence and are believed to result in irreversible capacity loss in the cells

  14. The Electronic Thermal Conductivity of Graphene.

    Science.gov (United States)

    Kim, Tae Yun; Park, Cheol-Hwan; Marzari, Nicola

    2016-04-13

    Graphene, as a semimetal with the largest known thermal conductivity, is an ideal system to study the interplay between electronic and lattice contributions to thermal transport. While the total electrical and thermal conductivity have been extensively investigated, a detailed first-principles study of its electronic thermal conductivity is still missing. Here, we first characterize the electron-phonon intrinsic contribution to the electronic thermal resistivity of graphene as a function of doping using electronic and phonon dispersions and electron-phonon couplings calculated from first-principles at the level of density-functional theory and many-body perturbation theory (GW). Then, we include extrinsic electron-impurity scattering using low-temperature experimental estimates. Under these conditions, we find that the in-plane electronic thermal conductivity κe of doped graphene is ∼300 W/mK at room temperature, independently of doping. This result is much larger than expected and comparable to the total thermal conductivity of typical metals, contributing ∼10% to the total thermal conductivity of bulk graphene. Notably, in samples whose physical or domain sizes are of the order of few micrometers or smaller, the relative contribution coming from the electronic thermal conductivity is more important than in the bulk limit, because lattice thermal conductivity is much more sensitive to sample or grain size at these scales. Last, when electron-impurity scattering effects are included we find that the electronic thermal conductivity is reduced by 30 to 70%. We also find that the Wiedemann-Franz law is broadly satisfied at low and high temperatures but with the largest deviations of 20-50% around room temperature.

  15. Can electronic stability control replace studded tyres?

    DEFF Research Database (Denmark)

    Elvik, Rune

    2015-01-01

    Highlights • Electronic stability control can substitute studded tyres. • This makes it easier to discourage the use of studded tyres. • A certain level of use of studded tyres makes roads less slippery.......Highlights • Electronic stability control can substitute studded tyres. • This makes it easier to discourage the use of studded tyres. • A certain level of use of studded tyres makes roads less slippery....

  16. Advanced thermal management technologies for defense electronics

    Science.gov (United States)

    Bloschock, Kristen P.; Bar-Cohen, Avram

    2012-05-01

    Thermal management technology plays a key role in the continuing miniaturization, performance improvements, and higher reliability of electronic systems. For the past decade, and particularly, the past 4 years, the Defense Advanced Research Projects Agency (DARPA) has aggressively pursued the application of micro- and nano-technology to reduce or remove thermal constraints on the performance of defense electronic systems. The DARPA Thermal Management Technologies (TMT) portfolio is comprised of five technical thrust areas: Thermal Ground Plane (TGP), Microtechnologies for Air-Cooled Exchangers (MACE), NanoThermal Interfaces (NTI), Active Cooling Modules (ACM), and Near Junction Thermal Transport (NJTT). An overview of the TMT program will be presented with emphasis on the goals and status of these efforts relative to the current State-of-the-Art. The presentation will close with future challenges and opportunities in the thermal management of defense electronics.

  17. Thermal stability of manganese-stabilized stainless steels

    International Nuclear Information System (INIS)

    Klueh, R.L.; Kenik, E.A.

    1993-01-01

    Previous work on a series of experimental high-manganese reduced-activation austenitic stainless steels demonstrated that they have improved tensile properties relative to type 316 stainless steel in both the annealed and 20% cold-worked conditions. Steels were tested with an Fe-20Mn-12Cr-0.25C (in weight percent) base composition, to which various combinations of Ti, W, V, P, and B were added. Tensile tests have now been completed on these steels after thermal aging at 600 degrees C. Thermal stability varied with composition, but the alloys were as stable or more stable than type 316 stainless steel. the strength of the annealed steels increased slightly after aging to 5000 h, while a strength decrease occurred for the cold worked steel. In both conditions, a steel containing a combination of all the alloying elements was most stable and had the best strength after thermal aging 5000 h at 600 degrees C. Despite having much higher strength than 316 stainless steel after aging, the ductility of the strongest experimental alloy was still as good as that of 316 stainless steel

  18. Thermal stability of detonation-produced micro and nanodiamonds

    Science.gov (United States)

    Efremov, V. P.; Zakatilova, E. I.; Maklashova, I. V.; Shevchenko, N. V.

    2018-01-01

    Detonation nanodiamonds are produced at utilization of high explosives. When an explosive blasts in a water environment, the detonation products contain microdiamonds, and in a gaseous medium, nanodiamonds. It is known that with decreasing size the influence of the surface energy of particles on their properties increases. Thus, it is interesting to compare the properties of detonation nano and microdiamonds. In this study, we have examined the thermal stability of diamond materials by synchronous thermal analysis. The experiments were performed at atmospheric pressure in argon flow for different heating rates in a range from room temperature to 1500 °C. Samples of initial and annealed micro and nanomaterials were studied using electron microscopy, x-ray and x-ray-fluorescence analysis. It was established that thermal and structural properties of micro and nanodiamonds differ substantially.

  19. Organic transistors with high thermal stability for medical applications.

    Science.gov (United States)

    Kuribara, Kazunori; Wang, He; Uchiyama, Naoya; Fukuda, Kenjiro; Yokota, Tomoyuki; Zschieschang, Ute; Jaye, Cherno; Fischer, Daniel; Klauk, Hagen; Yamamoto, Tatsuya; Takimiya, Kazuo; Ikeda, Masaaki; Kuwabara, Hirokazu; Sekitani, Tsuyoshi; Loo, Yueh-Lin; Someya, Takao

    2012-03-06

    The excellent mechanical flexibility of organic electronic devices is expected to open up a range of new application opportunities in electronics, such as flexible displays, robotic sensors, and biological and medical electronic applications. However, one of the major remaining issues for organic devices is their instability, especially their thermal instability, because low melting temperatures and large thermal expansion coefficients of organic materials cause thermal degradation. Here we demonstrate the fabrication of flexible thin-film transistors with excellent thermal stability and their viability for biomedical sterilization processes. The organic thin-film transistors comprise a high-mobility organic semiconductor, dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene, and thin gate dielectrics comprising a 2-nm-thick self-assembled monolayer and a 4-nm-thick aluminium oxide layer. The transistors exhibit a mobility of 1.2 cm(2) V(-1)s(-1) within a 2 V operation and are stable even after exposure to conditions typically used for medical sterilization.

  20. Calibrating thermal behavior of electronics

    Science.gov (United States)

    Chainer, Timothy J.; Parida, Pritish R.; Schultz, Mark D.

    2016-05-31

    A method includes determining a relationship between indirect thermal data for a processor and a measured temperature associated with the processor, during a calibration process, obtaining the indirect thermal data for the processor during actual operation of the processor, and determining an actual significant temperature associated with the processor during the actual operation using the indirect thermal data for the processor during actual operation of the processor and the relationship.

  1. Thermal stability of biodiesel in supercritical methanol

    Energy Technology Data Exchange (ETDEWEB)

    Hiroaki Imahara; Eiji Minami; Shusaku Hari; Shiro Saka [Kyoto University, Kyoto (Japan). Department of Socio-Environmental Energy Science

    2008-01-15

    Non-catalytic biodiesel production technologies from oils/fats in plants and animals have been developed in our laboratory employing supercritical methanol. Due to conditions in high temperature and high pressure of the supercritical fluid, thermal stability of fatty acid methyl esters and actual biodiesel prepared from various plant oils was studied in supercritical methanol over a range of its condition between 270{sup o}C/17 MPa and 380{sup o}C/56 MPa. In addition, the effect of thermal degradation on cold flow properties was studied. As a result, it was found that all fatty acid methyl esters including poly-unsaturated ones were stable at 270{sup o}C/17 MPa, but at 350{sup o}C/43 MPa, they were partly decomposed to reduce the yield with isomerization from cis-type to trans-type. These behaviors were also observed for actual biodiesel prepared from linseed oil, safflower oil, which are high in poly-unsaturated fatty acids. Cold flow properties of actual biodiesel, however, remained almost unchanged after supercritical methanol exposure at 270{sup o}C/17 MPa and 350{sup o}C/43 MPa. For the latter condition, however, poly-unsaturated fatty acids were sacrificed to be decomposed and reduced in yield. From these results, it was clarified that reaction temperature in supercritical methanol process should be lower than 300{sup o}C, preferably 270{sup o}C with a supercritical pressure higher than 8.09 MPa, in terms of thermal stabilization for high-quality biodiesel production. 9 refs., 3 figs., 4 tabs.

  2. Stability of Trapped Electrons in SiO(2)

    International Nuclear Information System (INIS)

    Fleetwood, D.M.; Winokur, P.S.

    1999-01-01

    Thermally stimulated current and capacitance voltage methods are used to investigate the thermal stability of trapped electrons associated with radiation-induced trapped positive charge in metal-oxide-semiconductor capacitors. The density of deeply trapped electrons in radiation-hardened 45 nm oxides exceeds that of shallow electrons by a factor of ∼3 after radiation exposure, and by up to a factor of 10 or more during biased annealing. Shallow electron traps anneal faster than deep traps, and seem to be at least qualitatively consistent with the model of Lelis et al. Deeper traps maybe part of a fundamentally distinct dipole complex, and/or have shifted energy levels that inhibit charge exchange with the Si

  3. Low-Temperature Bainite: A Thermal Stability Study

    Science.gov (United States)

    Santajuana, Miguel A.; Rementeria, Rosalia; Kuntz, Matthias; Jimenez, Jose A.; Caballero, Francisca G.; Garcia-Mateo, Carlos

    2018-06-01

    The thermal stability of nanobainitic structures obtained by heat treating two different high-carbon high-silicon steels at temperatures between 200 °C and 600 °C has been investigated by means of three complementary techniques, i.e., field emission gun-scanning electron microscopy, X-ray diffraction, and high-resolution dilatometry. Three main stages have been established, each of them characterized by a distinctive microstructure. Furthermore, the nanocrystalline structure generated by the bainite reaction confers the steel with an extraordinary tempering resistance.

  4. Thermal management of electronics: A review of literature

    Directory of Open Access Journals (Sweden)

    Anandan Sundaram Shanmuga

    2008-01-01

    Full Text Available Due to rapid growth in semiconductor technology, there is a continuous increase of the system power and the shrinkage of size. This resulted in inevitable challenges in the field of thermal management of electronics to maintain the desirable operating temperature. The present paper reviews the literature dealing with various aspects of cooling methods. Included are papers on experimental work on analyzing cooling technique and its stability, numerical modeling, natural convection, and advanced cooling methods. The issues of thermal management of electronics, development of new effective cooling schemes by using advanced materials and manufacturing methods are also enumerated in this paper. .

  5. Study on the effect of shape-stabilized phase change materials on spacecraft thermal control in extreme thermal environment

    International Nuclear Information System (INIS)

    Wu, Wan-fan; Liu, Na; Cheng, Wen-long; Liu, Yi

    2013-01-01

    Highlights: ► A shape-stabilized PCM is used to protect the spacecraft attacked by high energy. ► Taking a satellite as example, it proves the solution given in the work is feasible. ► Low thermal conductivity makes the material above its thermal stability limit. ► It provides guidance on how to choose the shape-stabilized PCM for similar problems. - Abstract: In space, the emergencies such as short-term high heat flux is prone to cause spacecraft thermal control system faults, resulting in temperature anomalies of electronic equipment of the spacecraft and even failures in them. In order to protect the spacecraft attacked by the high energy, a new guard method is proposed. A shape-stabilized phase change material (PCM), which has high thermal conductivity and does not require being tightly packaged, is proposed to be used on the spacecraft. To prove the feasibility of using the material on spacecraft attacked by high energy, the thermal responses for spacecraft with shape-stabilized PCM are investigated in situations of normal and short-term high heat flux, in contrast to that with conventional thermal control system. The results indicate that the shape-stabilized PCM can effectively absorb the heat to prevent the thermal control system faults when the spacecraft’s outer heat flux changes dramatically and has no negative effect on spacecraft in normal heat flux. Additionally the effect of thermal conductivity of PCM on its application effectiveness is discussed

  6. A low energy electron microscopy study of the initial growth, structure and thermal stability of BDA-domains on Cu(001)

    NARCIS (Netherlands)

    Khokhar, F.S.; van Gastel, Raoul; Schwarz, Daniel; Schwarz, Daniel; Zandvliet, Henricus J.W.; Poelsema, Bene

    2011-01-01

    The growth of 4,4′-biphenyldicarboxylic acid (BDA) on Cu(001) has been studied using low energy electron microscopy and selective area low energy electron diffraction. The emergence of large islands and hydrogen bonding to perpendicularly oriented, adjacent molecules is confirmed. The two benzene

  7. Thermal stabilization of uranium mill tailings

    International Nuclear Information System (INIS)

    Dreesen, D.R.; Williams, J.M.; Cokal, E.J.

    1981-01-01

    The sintering of tailings at high temperatures (1200 0 C) has shown promise as a conditioning approach that greatly reduces the 222 Rn emanation of uranium mill tailings. The structure of thermally stabilized tailings has been appreciably altered producing a material that will have minimal management requirements and will be applicable to on-site processing and disposal. The mineralogy of untreated tailings is presented to define the structure of the original materials. Quartz predominates in most tailings samples; however, appreciable quantities of gypsum, clay, illite, or albites are found in some tailings. Samples from the Durango and Shiprock sites have plagioclase-type aluminosilicates and non-aluminum silicates as major components. The iron-rich vanadium tailings from the Salt Lake City site contain appreciable quantities of α-hematite and chloroapatite. The reduction in radon emanation power and changes in mineralogy as a function of sintering temperature are presented

  8. Thermal stability of rare earth oxychlorides

    International Nuclear Information System (INIS)

    Bunda, V.V.; Shtilikha, M.V.; Golovej, V.M.

    1984-01-01

    The thermal stability of oxichlorides of the lanthanum series is investigated to determine the possibility of preparing them in the form of crystals by the method of l chemical gas-transport reactions (CTR). The lanthanide oxichlorides were subjected to thermogravimetric studies in the 20-1500 deg C temperature range under normal conditions. The temperatures of initiation of incongruent decomposition reactions are found. It is found that the process of LnOCl decomposition is preceeded by the exothermal effect connected with the Ln 2 OCl 4 recrsytallization to LnOCl. The thermodynamic and kinetic parameters of decomposition reactions are determined, such as reaction heats ΔH, decomposition rate constants K, dissociation energies E, reaction orders n. The LnOCl specific heats (Csub(P))sub(T) are estimated. It is shown that the LnOCl compounds can be prepared in the form of monocrystals by the CTR method

  9. Power Electronics Thermal Management R&D

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, Gilbert; Bennion, Kevin

    2016-06-08

    This project will develop thermal management strategies to enable efficient and high-temperature wide-bandgap (WBG)-based power electronic systems (e.g., emerging inverter and DC-DC converter designs). The use of WBG-based devices in automotive power electronics will improve efficiency and increase driving range in electric-drive vehicles; however, the implementation of this technology is limited, in part, due to thermal issues. This project will develop system-level thermal models to determine the thermal limitations of current automotive power modules under elevated device temperature conditions. Additionally, novel cooling concepts and material selection will be evaluated to enable high-temperature silicon and WBG devices in power electronics components. WBG devices (silicon carbide [SiC], gallium nitride [GaN]) promise to increase efficiency, but will be driven as hard as possible. This creates challenges for thermal management and reliability.

  10. Thermal stability of tagatose in solution.

    Science.gov (United States)

    Luecke, Katherine J; Bell, Leonard N

    2010-05-01

    Tagatose, a monosaccharide similar to fructose, has been shown to behave as a prebiotic. To deliver this prebiotic benefit, tagatose must not degrade during the processing of foods and beverages. The objective of this study was to evaluate the thermal stability of tagatose in solutions. Tagatose solutions were prepared in 0.02 and 0.1 M phosphate and citrate buffers at pHs 3 and 7, which were then held at 60, 70, and 80 degrees C. Pseudo-1st-order rate constants for tagatose degradation were determined. In citrate and phosphate buffers at pH 3, minimal tagatose was lost and slight browning was observed. At pH 7, tagatose degradation rates were enhanced. Degradation was faster in phosphate buffer than citrate buffer. Higher buffer concentrations also increased the degradation rate constants. Enhanced browning accompanied tagatose degradation in all buffer solutions at pH 7. Using the activation energies for tagatose degradation, less than 0.5% and 0.02% tagatose would be lost under basic vat and HTST pasteurization conditions, respectively. Although tagatose does breakdown at elevated temperatures, the amount of tagatose lost during typical thermal processing conditions would be virtually negligible. Practical Application: Tagatose degradation occurs minimally during pasteurization, which may allow for its incorporation into beverages as a prebiotic.

  11. The thermal stability of yellow fever vaccines

    Directory of Open Access Journals (Sweden)

    Ricardo Ishak

    1990-09-01

    Full Text Available The assessment of yellow fever vaccine thermostability both in lyophilized form and after reconstitution were analyzed. Two commercial yellow fever vaccines were assayed for their thermal stability. Vaccines were exposed to test temperatures in the range of 8 (graus C to 45 (graus C. Residual infectivity was measured by a plaque assay using Vero cells. The titre values were used in an accelerated degradation test that follows the Arrhenius equation and the minimum immunizing dose was assumed to be 10 (ao cubo particles forming unit (pfu/dose. Some of the most relevant results include that (i regular culture medium show the same degradation pattern of a reconstituted 17D-204 vaccine; (ii reconstituted YF-17D-204 showed a predictable half life of more than six days if kept at 0 (graus C; (iii there are differences in thermostability between different products that are probably due to both presence of stabilizers in the preparation and the modernization in the vaccine production; (iv it is important to establish a proper correlation between the mouse infectivity test and the plaque assay since the last appears to be more simple, economical, and practical for small laboratories to assess the potency of the vaccine, and (v the accelerated degradation test appears to be the best procedure to quantify the thermostability of biological products.

  12. Density Gradient Stabilization of Electron Temperature Gradient Driven Turbulence in a Spherical Tokamak

    International Nuclear Information System (INIS)

    Ren, Y.; Kaye, S.M.; Mazzucato, E.; Guttenfelder, W.; Bell, R.E.; Domier, C.W.; LeBlanc, B.P.; Lee, K.C.; Luhmann, N.C. Jr.; Smith, D.R.; Yuh, H.

    2011-01-01

    In this letter we report the first clear experimental observation of density gradient stabilization of electron temperature gradient driven turbulence in a fusion plasma. It is observed that longer wavelength modes, k (perpendicular) ρ s ∼< 10, are most stabilized by density gradient, and the stabilization is accompanied by about a factor of two decrease in the plasma effective thermal diffusivity.

  13. System evaluation of improved thermal stability jet fuels

    Energy Technology Data Exchange (ETDEWEB)

    Binns, K.E.; Dieterle, G.L.; Williams, T. [Univ. of Dayton Research Institute, OH (United States)

    1995-05-01

    A single-pass, single-tube heat exchanger device called the Phoenix rig and a single-pass, dual-heat exchanger system called the Extended Duration Thermal Stability Test system are specific devices/systems developed for evaluating jet fuel thermal stability. They have been used extensively in the evaluation of various jet fuels and thermal stability additives. The test results have indicated that additives can substantially improve the thermal stability of conventional jet fuels. Relationships of oxygen consumption, residence time, bulk, and wetted wall temperatures on coking deposits that form in the heated tubes have also been investigated.

  14. Thermal stability of carbon nanotubes probed by anchored tungsten nanoparticles

    Directory of Open Access Journals (Sweden)

    Xianlong Wei, Ming-Sheng Wang, Yoshio Bando and Dmitri Golberg

    2011-01-01

    Full Text Available The thermal stability of multiwalled carbon nanotubes (CNTs was studied in high vacuum using tungsten nanoparticles as miniaturized thermal probes. The particles were placed on CNTs inside a high-resolution transmission electron microscope equipped with a scanning tunneling microscope unit. The setup allowed manipulating individual nanoparticles and heating individual CNTs by applying current to them. CNTs were found to withstand high temperatures, up to the melting point of 60-nm-diameter W particles (~3400 K. The dynamics of W particles on a hot CNT, including particle crystallization, quasimelting, melting, sublimation and intradiffusion, were observed in real time and recorded as a video. Graphite layers reel off CNTs when melted or premelted W particles revolve along the tube axis.

  15. Thermal stability and environmental compatibility of Inconel 617

    International Nuclear Information System (INIS)

    Kimball, O.F.

    1989-01-01

    The thermal stability and environmental compatibility of Inconel 617, a prime nuclear process heat steam reformer candidate alloy, are described in this paper. This commercially available wrought nickel-base alloy has excellent high-temperature strength but is subject to loss of toughness and ductility due to thermal instability. Work done to improve the thermal stability of this alloy is discussed. Room-temperature tensile and toughness data and microstructural information for Inconel 617 specimens exposed at elevated temperatures are presented. Preliminary data indicate that controlling the chemistry of Inconel 617 can provide a substantial improvement in thermal stability. Preliminary work to define the range of high-temperature gas-cooled reactor (HTGR) primary coolant compositions within which minimal deleterious gas/metal reactions occur with Inconel 617 is described. Within this gas chemistry range a stable surface oxide forms and only slight carburization occurs. In other gas chemistry ranges, rapid carburization or decarburization can occur. The gas corrosion experiments discussed are part of a series of relatively short-term exposures to HTGR helium in which the effects of different H 2 O concentrations (0.01 to 1.0 Pa) were determined as a function of the systematic variation of a second constituent (CO and CH 4 for this work) in the test gas. The composition of the basic HTGR helium was 40 Pa H 2 , 4 Pa CO, 0.02 Pa CO 2 , 2 Pa CH 4 in helium at 0.2 MPa. Two other CO levels (1 and 12 Pa) and one additional CH 4 level (0.63 Pa) were used in these experiments. Experimental exposure methods are discussed and the results of gas-metal interaction studies are presented. These results include carbon analyses and optical and scanning electron microscopy to determine the morphology and type of surface and subsurface microstructures. (author). 15 refs, 6 figs, 5 tabs

  16. Preparation, structure and thermal stability of Cu/LDPE nanocomposites

    International Nuclear Information System (INIS)

    Xia Xianping; Cai Shuizhou; Xie Changsheng

    2006-01-01

    Copper/low-density-polyethylene (Cu/LDPE) nanocomposites have been prepared using a melt-blending technique in a single-screw extruder. Their structure and thermal characteristics are characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results of XRD, SEM and SEM-EDS Cu-mapping show that the nanocomposites are a hybrid of the polymer and the copper nanoparticles, and the copper nanoparticles aggregates were distributed uniformly in general. The results also show that the nanocomposites and the base resin, the pure LDPE, have a different crystalline structure and the same oriented characteristics owing to the presence of copper nanoparticles and the same cooling condition. The results of DSC show that the incorporation of copper nanoparticles can decrease the melting temperatures but increase the crystallization temperatures, and can lower the crystallinity degree of the matrix of the composites. The results of TGA show that the presence of copper nanoparticles can improve the thermal stability of the nanocomposites, a maximum increment of 18 deg. C is obtained comparing with the pure LDPE in this experiment. The results of TGA also show that the influence of the incorporation of the copper nanoparticles on the thermal stability of the Cu/LDPE nanocomposites is different from that of the non-metal nanoparticles on the polymer/non-metal nanocomposites and the copper microparticles on the Cu/LDPE microcomposites. The increase of the thermal stability of the Cu/LDPE nanocomposites will decrease when the content of the copper nanoparticles is more than 2 wt.%. The difference might be caused by the fact that the activity of the metal nanoparticles is much more higher than that of the non-metal nanoparticles, and the different size effect the different copper particles has

  17. Thermal electron heating rate: a derivation

    International Nuclear Information System (INIS)

    Hoegy, W.R.

    1983-11-01

    The thermal electron heating rate is an important heat source term in the ionospheric electron energy balance equation, representing heating by photoelectrons or by precipitating higher energy electrons. A formula for the thermal electron heating rate is derived from the kinetic equation using the electron-electron collision operator as given by the unified theory of Kihara and Aono. This collision operator includes collective interactions to produce a finite collision operator with an exact Coulomb logarithm term. The derived heating rate O(e) is the sum of three terms, O(e) O(p) + S + O(int), which are respectively: (1) primary electron production term giving the heating from newly created electrons that have not yet suffered collisions with the ambient electrons, (2) a heating term evaluated on the energy surface m(e)/2 E(T) at the transition between Maxwellian and tail electrons at E(T), and (3) the integral term representing heating of Maxwellian electrons by energetic tail electrons at energies ET. Published ionospheric electron temperature studies used only the integral term O(int) with differing lower integration limits. Use of the incomplete heating rate could lead to erroneous conclusions regarding electron heat balance, since O(e) is greater than O(int) by as much as a factor of two

  18. A low energy electron microscopy study of the initial growth, structure, and thermal stability of 4,4'-biphenyldicarboxylic acid domains on Cu(001)

    International Nuclear Information System (INIS)

    Khokhar, Fawad S.; Gastel, Raoul van; Schwarz, Daniel; Zandvliet, Harold J. W.; Poelsema, Bene

    2011-01-01

    The growth of 4,4 ' -biphenyldicarboxylic acid (BDA) on Cu(001) has been studied using low energy electron microscopy and selective area low energy electron diffraction. The emergence of large islands and hydrogen bonding to perpendicularly oriented, adjacent molecules is confirmed. The two benzene rings of adsorbed BDA are twisted along the molecular axis. Unconventional growth of the domains, followed by a second nucleation stage, is observed at room temperature. This unanticipated feature is attributed to the accumulation of stress in the islands. Ostwald ripening in the films and the decay of BDA domains at 448 K exhibits features that are consistent with diffusion limited behavior.

  19. A low energy electron microscopy study of the initial growth, structure, and thermal stability of 4,4{sup '}-biphenyldicarboxylic acid domains on Cu(001)

    Energy Technology Data Exchange (ETDEWEB)

    Khokhar, Fawad S.; Gastel, Raoul van; Schwarz, Daniel; Zandvliet, Harold J. W.; Poelsema, Bene [Physics of Interfaces and Nanomaterials, MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, NL-7500AE Enschede (Netherlands)

    2011-09-28

    The growth of 4,4{sup '}-biphenyldicarboxylic acid (BDA) on Cu(001) has been studied using low energy electron microscopy and selective area low energy electron diffraction. The emergence of large islands and hydrogen bonding to perpendicularly oriented, adjacent molecules is confirmed. The two benzene rings of adsorbed BDA are twisted along the molecular axis. Unconventional growth of the domains, followed by a second nucleation stage, is observed at room temperature. This unanticipated feature is attributed to the accumulation of stress in the islands. Ostwald ripening in the films and the decay of BDA domains at 448 K exhibits features that are consistent with diffusion limited behavior.

  20. Thermally conductive, dielectric PCM-boron nitride nanosheet composites for efficient electronic system thermal management.

    Science.gov (United States)

    Yang, Zhi; Zhou, Lihui; Luo, Wei; Wan, Jiayu; Dai, Jiaqi; Han, Xiaogang; Fu, Kun; Henderson, Doug; Yang, Bao; Hu, Liangbing

    2016-11-24

    Phase change materials (PCMs) possessing ideal properties, such as superior mass specific heat of fusion, low cost, light weight, excellent thermal stability as well as isothermal phase change behavior, have drawn considerable attention for thermal management systems. Currently, the low thermal conductivity of PCMs (usually less than 1 W mK -1 ) greatly limits their heat dissipation performance in thermal management applications. Hexagonal boron nitride (h-BN) is a two-dimensional material known for its excellent thermally conductive and electrically insulating properties, which make it a promising candidate to be used in electronic systems for thermal management. In this work, a composite, consisting of h-BN nanosheets (BNNSs) and commercialized paraffin wax was developed, which inherits high thermally conductive and electrically insulating properties from BNNSs and substantial heat of fusion from paraffin wax. With the help of BNNSs, the thermal conductivity of wax-BNNS composites reaches 3.47 W mK -1 , which exhibits a 12-time enhancement compared to that of pristine wax (0.29 W mK -1 ). Moreover, an 11.3-13.3 MV m -1 breakdown voltage of wax-BNNS composites was achieved, which shows further improved electrical insulating properties. Simultaneously enhanced thermally conductive and electrically insulating properties of wax-BNNS composites demonstrate their promising application for thermal management in electronic systems.

  1. Electron thermal conduction in LASNEX

    International Nuclear Information System (INIS)

    Munro, D.; Weber, S.

    1994-01-01

    This report is a transcription of hand-written notes by DM dated 29 January 1986, transcribed by SW, with some clarifying comments added and details specific to running the LASNEX code deleted. Reference to the esoteric measurement units employed in LASNEX has also been deleted by SW (hopefully, without introducing errors in the numerical constants). The report describes the physics equations only, and only of electron conduction. That is, it does not describe the numerical method, which may be finite difference or finite element treatment in space, and (usually) implicit treatment in time. It does not touch on other electron transport packages which are available, and which include suprathermal electrons, nonlocal conduction, Krook model conduction, and modifications to electron conduction by magnetic fields. Nevertheless, this model is employed for the preponderance of LASNEX simulations

  2. STUDY OF THERMAL AND ACID STABILITY OF BENTONITE CLAY

    Directory of Open Access Journals (Sweden)

    Karna Wijaya

    2010-06-01

    Full Text Available The thermal and acid stability of the bentonite clays (Na- and Ca-bentonite have been tested. The thermal stability testing has been carried out by heating 5 gram of the clays  for five hours at 200, 300 and 500 °C respectively, meanwhile acid stability testing was performed by immersing 5 gram clays into 100 mL sulphuric acid 1M, 2M and 3M for 24 hours. The tested clays, then were characterized by means of X-Ray difractometry and IR-spectroscopy methods. The characterization results showed that upon heating, both Ca- and Na-bentonites indicated same thermal stability. However, upon acid treatment, Na-bentonite was found relatively stabiler and more resistance then Ca-bentonite.   Keywords: bentonite, clay, thermal stability, acid stability.

  3. Si-substituted hydroxyapatite nanopowders: Synthesis, thermal stability and sinterability

    International Nuclear Information System (INIS)

    Bianco, Alessandra; Cacciotti, Ilaria; Lombardi, Mariangela; Montanaro, Laura

    2009-01-01

    Synthetic hydroxyapatites incorporating small amounts of Si have shown improved biological performances in terms of enhanced bone apposition, bone in-growth and cell-mediated degradation. This paper reports a systematic investigation on Si-substituted hydroxyapatite (Si 1.40 wt%) nanopowders produced following two different conventional wet methodologies: (a) precipitation of Ca(NO 3 ) 2 .4H 2 O and (b) titration of Ca(OH) 2 . The influence of the synthesis process on composition, thermal behaviour and sinterability of the resulting nanopowders is studied. Samples were characterised by electron microscopy, induced coupled plasma atomic emission spectroscopy, thermal analysis, infrared spectroscopy, N 2 adsorption measurements, X-ray diffraction and dilatometry. Semicrystalline Si-substituted hydroxyapatite powders made up of needle-like nanoparticles were obtained, the specific surface area ranged between 84 and 110 m 2 /g. Pure and Si-substituted hydroxyapatite nanopowders derived from Ca(NO 3 ) 2 .4H 2 O decomposed around 1000 deg. C. Si-substituted hydroxyapatite nanopowders obtained from Ca(OH) 2 were thermally stable up to 1200 deg. C and showed a distinct decreased thermal stability with respect to the homologous pure sample. Si-substituted hydroxyapatites exhibited higher sintering temperature and increased total shrinkage with respect to pure powders. Nanostructured dense ceramics were obtained by sintering at 1100 deg. C Si-substituted hydroxyapatites derived from Ca(OH) 2

  4. Increasing Laser Stability with Improved Electronic Instruments

    Science.gov (United States)

    Troxel, Daylin; Bennett, Aaron; Erickson, Christopher J.; Jones, Tyler; Durfee, Dallin S.

    2010-03-01

    We present several electronic instruments developed to implement an ultra-stable laser lock. These instruments include a high speed, low noise homodyne photo-detector; an ultrahigh stability, low noise current driver with high modulation bandwidth and digital control; a high-speed, low noise PID controller; a low-noise piezo driver; and a laser diode temperature controller. We will present the theory of operation for these instruments, design and construction techniques, and essential characteristics for each device.

  5. Mechanical and thermal stability of graphene and graphene-based materials

    Science.gov (United States)

    Galashev, A. E.; Rakhmanova, O. R.

    2014-10-01

    Graphene has rapidly become one of the most popular materials for technological applications and a test material for new condensed matter ideas. This paper reviews the mechanical properties of graphene and effects related to them that have recently been discovered experimentally or predicted theoretically or by simulation. The topics discussed are of key importance for graphene's use in integrated electronics, thermal materials, and electromechanical devices and include the following: graphene transformation into other sp^2 hybridization forms; stability to stretching and compression; ion-beam-induced structural modifications; how defects and graphene edges affect the electronic properties and thermal stability of graphene and related composites.

  6. Stability of thermally induced copper precipitates under neutron irradiation

    International Nuclear Information System (INIS)

    Phythian, W.J.; Dumbill, S.; Brown, P.; Sinclair, R.

    1993-01-01

    Model Fe 1.3%Cu and Fe 1.3%Cu 1.1%Ni alloys have been thermally aged at 550 C for 2 hours (peak) and 10 hours prior to irradiation at 288 C to a dose of 5.10 22 n/m 2 . Results of a microstructural investigation using dedicated field emission gun scanning transmission electron microscopy (FEGSTEM) and small angle neutron scattering (SANS) to assess precipitate stability in the binary alloy, are presented. These data are then used to predict a hardness change as a result of copper precipitation for comparison with the measured values obtained using standard 5 kg Vickers hardness tests on the SANS samples. Implications of these data to the re-embrittlement of the RPV by subsequent copper precipitation is discussed. (authors). 16 refs., 5 figs., 5 tabs

  7. Stability of thermally induced copper precipitates under neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Phythian, W J; Dumbill, S; Brown, P; Sinclair, R [AEA Technology, Harwell (United Kingdom)

    1994-12-31

    Model Fe 1.3%Cu and Fe 1.3%Cu 1.1%Ni alloys have been thermally aged at 550 C for 2 hours (peak) and 10 hours prior to irradiation at 288 C to a dose of 5.10{sup 22} n/m{sup 2}. Results of a microstructural investigation using dedicated field emission gun scanning transmission electron microscopy (FEGSTEM) and small angle neutron scattering (SANS) to assess precipitate stability in the binary alloy, are presented. These data are then used to predict a hardness change as a result of copper precipitation for comparison with the measured values obtained using standard 5 kg Vickers hardness tests on the SANS samples. Implications of these data to the re-embrittlement of the RPV by subsequent copper precipitation is discussed. (authors). 16 refs., 5 figs., 5 tabs.

  8. Stability and electronic properties of silicene on WSe2

    KAUST Repository

    Zhu, Jiajie

    2015-03-17

    Many semiconducting substrates, such as GaS and MgBr2, have been explored for silicene. However, large lattice mismatches, complicated control of terminal layers and small band gaps are critical limiting factors. First-principles results on the stability and electronic properties of silicene on WSe2 show that the energy barriers for lateral translation between the two subsystems are very small due to weak van der Waals interactions. For the same reason, the Dirac physics of silicene is preserved. It turns out that the induced band gap is sufficient to withstand thermal fluctuations. This journal is © The Royal Society of Chemistry 2015.

  9. Thermal stability of α-amylase in aqueous cosolvent systems

    Indian Academy of Sciences (India)

    Prakash

    The activity and thermal stability of α-amylase were studied in the presence of different concentrations of ... 2.1 Materials ..... unfavourable free energy of transfer of amino acid side ..... folded protein with a hydrophobic dye: evidence that molten.

  10. Thermal stability of α-amylase in aqueous cosolvent systems

    Indian Academy of Sciences (India)

    Prakash

    Department of Protein Chemistry and Technology, Central Food Technological Research ... Keywords. α-Amylase; cosolvents; preferential interaction parameters; thermal stability ...... simulations of trehalose as a 'dynamic reducer' for solvent.

  11. Stabilization of electron-scale turbulence by electron density gradient in national spherical torus experiment

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz Ruiz, J.; White, A. E. [MIT-Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States); Ren, Y.; Guttenfelder, W.; Kaye, S. M.; Leblanc, B. P.; Mazzucato, E. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Lee, K. C. [National Fusion Research Institute, Daejeon (Korea, Republic of); Domier, C. W. [University of California at Davis, Davis, California 95616 (United States); Smith, D. R. [University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Yuh, H. [Nova Photonics, Inc., Princeton, New Jersey 08540 (United States)

    2015-12-15

    Theory and experiments have shown that electron temperature gradient (ETG) turbulence on the electron gyro-scale, k{sub ⊥}ρ{sub e} ≲ 1, can be responsible for anomalous electron thermal transport in NSTX. Electron scale (high-k) turbulence is diagnosed in NSTX with a high-k microwave scattering system [D. R. Smith et al., Rev. Sci. Instrum. 79, 123501 (2008)]. Here we report on stabilization effects of the electron density gradient on electron-scale density fluctuations in a set of neutral beam injection heated H-mode plasmas. We found that the absence of high-k density fluctuations from measurements is correlated with large equilibrium density gradient, which is shown to be consistent with linear stabilization of ETG modes due to the density gradient using the analytical ETG linear threshold in F. Jenko et al. [Phys. Plasmas 8, 4096 (2001)] and linear gyrokinetic simulations with GS2 [M. Kotschenreuther et al., Comput. Phys. Commun. 88, 128 (1995)]. We also found that the observed power of electron-scale turbulence (when it exists) is anti-correlated with the equilibrium density gradient, suggesting density gradient as a nonlinear stabilizing mechanism. Higher density gradients give rise to lower values of the plasma frame frequency, calculated based on the Doppler shift of the measured density fluctuations. Linear gyrokinetic simulations show that higher values of the electron density gradient reduce the value of the real frequency, in agreement with experimental observation. Nonlinear electron-scale gyrokinetic simulations show that high electron density gradient reduces electron heat flux and stiffness, and increases the ETG nonlinear threshold, consistent with experimental observations.

  12. Development of thermal stability additive packages for JP-8

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, S.D.; Harrison, W.E. III; Edwards, T.; Morris, R.W.; Shouse, D.T. [USAF Wright Lab., Wright-Paterson AFB, OH (United States)

    1995-05-01

    Advanced military aircraft use fuel as the primary heat sink to cool engine and airframe components. As the fuel is thermally stressed, thermal oxidative reactions take place that result in the formation of deposits. These deposits degrade aircraft performance and ultimately lead to premature servicing of the affected components. The frequency of these incidents, coupled with the projected cooling requirements for future systems, demonstrates that current thermal stability limits are inadequate. In response to this situation, the United States Air Force (USAF) has embarked on a program to improve thermal stability using specially formulated additive packages. Results indicate that additives offer significant thermal stability improvement. This paper describes the USAF program to develop and deploy an improved JP-8 for fleet-wide use by 1998.

  13. Thermal stability of novel polyurethane adhesives investigated by TGA

    Directory of Open Access Journals (Sweden)

    Mariusz Mamiński

    2014-05-01

    Full Text Available The objective of the work was an assessment of thermal stability of novel polyurethane wood adhesives by means of TGA. Hyperbranched polyglycerols of various structures were used as polyol components cured with polymeric methylenediphenyldiisocyanate (PMDI or polymeric hexamethylenediisocyanate (PHDI. Resultant adhesives were thermally degraded in temperature range 20 - 500ºC. Performance of polyurethane based on fully aliphatic polyglycerol was inferior to those based on polyglycerols bearing aromatic moieties. The differences in 50%-weight loss temperature achieving 27 - 39°C as well as residual weights at 480 ºC indicate the contribution of aromatic units presence within the macromonomer structure to increased thermal stability of polyurethane upon thermal degradation. Furthermore, temperature of 50% weight loss revealed that thermal stability of the developed hyperbranched polyglycerol-based adhesives was comparable to that of the commercial PUR adhesive.

  14. Power Electronics and Thermal Management | Transportation Research | NREL

    Science.gov (United States)

    Power Electronics and Thermal Management Power Electronics and Thermal Management This is the March Gearhart's testimony. Optical Thermal Characterization Enables High-Performance Electronics Applications New vehicle electronics systems are being developed at a rapid pace, and NREL is examining strategies to

  15. On thermal stability in incompressible slip flow

    International Nuclear Information System (INIS)

    Bestman, A.R.

    1990-12-01

    The paper considers the classical problem of the stability of a layer of fluid heated from below, but in the case when the density is low and there is slip flow at the bounding walls. The eigenvalue problem which ensures is tackled by taking cognisance of the orthogonality of Bessel function of the first kind. It is observed that the Rayleigh number for the onset of instability, for the case of marginal stability, is increased by gas rarefication. (author). 2 refs

  16. Optimal control theory applied to fusion plasma thermal stabilization

    International Nuclear Information System (INIS)

    Sager, G.; Miley, G.; Maya, I.

    1985-01-01

    Many authors have investigated stability characteristics and performance of various burn control schemes. The work presented here represents the first application of optimal control theory to the problem of fusion plasma thermal stabilization. The objectives of this initial investigation were to develop analysis methods, demonstrate tractability, and present some preliminary results of optimal control theory in burn control research

  17. Flute-interchange stability in a hot electron plasma

    International Nuclear Information System (INIS)

    Dominguez, R.R.

    1980-01-01

    Several topics in the kinetic stability theory of flute-interchange modes in a hot electron plasma are discussed. The stability analysis of the hot-electron, curvature-driven flute-interchange mode, previously performed in a slab geometry, is extended to a cylindrical plasma. The cold electron concentration necessary for stability differs substantially from previous criteria. The inclusion of a finite temperature background plasma in the stability analysis results in an ion curvature-driven flute-interchange mode which may be stabilized by either hot-electron diamagnetic effects, hot-electron plasma density, or finite (ion) Larmor radius effects

  18. Model Comparison for Electron Thermal Transport

    Science.gov (United States)

    Moses, Gregory; Chenhall, Jeffrey; Cao, Duc; Delettrez, Jacques

    2015-11-01

    Four electron thermal transport models are compared for their ability to accurately and efficiently model non-local behavior in ICF simulations. Goncharov's transport model has accurately predicted shock timing in implosion simulations but is computationally slow and limited to 1D. The iSNB (implicit Schurtz Nicolai Busquet electron thermal transport method of Cao et al. uses multigroup diffusion to speed up the calculation. Chenhall has expanded upon the iSNB diffusion model to a higher order simplified P3 approximation and a Monte Carlo transport model, to bridge the gap between the iSNB and Goncharov models while maintaining computational efficiency. Comparisons of the above models for several test problems will be presented. This work was supported by Sandia National Laboratory - Albuquerque and the University of Rochester Laboratory for Laser Energetics.

  19. Thermal conductivity of ytterbia-stabilized zirconia

    International Nuclear Information System (INIS)

    Feng, Jing; Ren, Xiaorui; Wang, Xiaoyan; Zhou, Rong; Pan, Wei

    2012-01-01

    The 3–10 mol.% Yb 2 O 3 –ZrO 2 (YbSZ) ceramics were synthesized by solid reaction methods and sintered at 1600 °C. The phases were identified by high-resolution X-ray diffraction with a K α1 monochromator, and it was found that the tetragonal-prime phases exist in 3–6 mol.% YbSZ. The thermal conductivity of the sintered YbSZ ceramics were measured using a laser flash method and it was demonstrated that the values of the thermal conductivities of the 5 and 10 mol.% YbSZ ceramics are the lowest at high and room temperature, respectively, and much lower than that of 7YSZ. The lower thermal conductivity of YbSZ ceramics may be due to the heavier dopant of ytterbium and the tetragonal-prime ZrO 2 phase.

  20. Thermal stability of radiation-modified polyethylene

    International Nuclear Information System (INIS)

    Vinogradova, T.B.; Sirota, A.G.; Bal'tenas, R.A.; Stanyavichus, V.I.; Knebel'man, A.M.; Sil'chenko, S.A.

    1989-01-01

    In the work reported here, the authors investigated the thermooxidative resistance, at temperatures from 373 to 473 K, of polyethylene that had been cross-linked by exposure to radiation and formulated with various heat stabilizers. Thus, these studies of the thermooxidative resistance of polyethylene-based compositions that have been cross-linked by the radiation-chemical method have shown that, in this particular series of heat-stabilizers, the greatest effect at temperatures of 373-473 K is given by the FAU-13. The DTPhDMI has the greatest heat-stabilizing effect in the temperature interval 448-473 K, whereas the heat resistance of materials containing Diaphen NN or Phenozan-23 is higher at 373-423 K. These comparative results are in agreement with data for unirradiated and chemically cross-linked polyethylene

  1. Thermal conductivity of electron-irradiated graphene

    Science.gov (United States)

    Weerasinghe, Asanka; Ramasubramaniam, Ashwin; Maroudas, Dimitrios

    2017-10-01

    We report results of a systematic analysis of thermal transport in electron-irradiated, including irradiation-induced amorphous, graphene sheets based on nonequilibrium molecular-dynamics simulations. We focus on the dependence of the thermal conductivity, k, of the irradiated graphene sheets on the inserted irradiation defect density, c, as well as the extent of defect passivation with hydrogen atoms. While the thermal conductivity of irradiated graphene decreases precipitously from that of pristine graphene, k0, upon introducing a low vacancy concentration, c reduction of the thermal conductivity with the increasing vacancy concentration exhibits a weaker dependence on c until the amorphization threshold. Beyond the onset of amorphization, the dependence of thermal conductivity on the vacancy concentration becomes significantly weaker, and k practically reaches a plateau value. Throughout the range of c and at all hydrogenation levels examined, the correlation k = k0(1 + αc)-1 gives an excellent description of the simulation results. The value of the coefficient α captures the overall strength of the numerous phonon scattering centers in the irradiated graphene sheets, which include monovacancies, vacancy clusters, carbon ring reconstructions, disorder, and a rough nonplanar sheet morphology. Hydrogen passivation increases the value of α, but the effect becomes very minor beyond the amorphization threshold.

  2. Thermal Plasma Generators with Water Stabilized Arc

    Czech Academy of Sciences Publication Activity Database

    Hrabovský, Milan

    2009-01-01

    Roč. 2, č. 1 (2009), s. 99-104 ISSN 1876-5343 R&D Projects: GA ČR GA202/08/1084 Institutional research plan: CEZ:AV0Z20430508 Keywords : Thermal plasma * plasma torch * Gerdien arc Subject RIV: BL - Plasma and Gas Discharge Physics http://www.bentham.org/open/toppj/openaccess2.htm

  3. Exploration of porous SiC nanostructures as thermal insulator with high thermal stability and low thermal conductivity

    Institute of Scientific and Technical Information of China (English)

    Peng; WAN; Jingyang; WANG

    2016-01-01

    The crucial challenge for current nanoscale thermal insulation materials,such as Al2O3 and SiO2 aerogel composites,is to solve the trade-off between extremely low thermal conductivity and unsatisfied thermal stability.Typical high-temperature ceramic SiC possesses excellent mechanical properties and

  4. Thermal Stability of Rhodopsin and Progression of Retinitis Pigmentosa

    Science.gov (United States)

    Liu, Monica Yun; Liu, Jian; Mehrotra, Devi; Liu, Yuting; Guo, Ying; Baldera-Aguayo, Pedro A.; Mooney, Victoria L.; Nour, Adel M.; Yan, Elsa C. Y.

    2013-01-01

    Over 100 point mutations in the rhodopsin gene have been associated with retinitis pigmentosa (RP), a family of inherited visual disorders. Among these, we focused on characterizing the S186W mutation. We compared the thermal properties of the S186W mutant with another RP-causing mutant, D190N, and with WT rhodopsin. To assess thermal stability, we measured the rate of two thermal reactions contributing to the thermal decay of rhodopsin as follows: thermal isomerization of 11-cis-retinal and hydrolysis of the protonated Schiff base linkage between the 11-cis-retinal chromophore and opsin protein. We used UV-visible spectroscopy and HPLC to examine the kinetics of these reactions at 37 and 55 °C for WT and mutant rhodopsin purified from HEK293 cells. Compared with WT rhodopsin and the D190N mutant, the S186W mutation dramatically increases the rates of both thermal isomerization and dark state hydrolysis of the Schiff base by 1–2 orders of magnitude. The results suggest that the S186W mutant thermally destabilizes rhodopsin by disrupting a hydrogen bond network at the receptor's active site. The decrease in the thermal stability of dark state rhodopsin is likely to be associated with higher levels of dark noise that undermine the sensitivity of rhodopsin, potentially accounting for night blindness in the early stages of RP. Further studies of the thermal stability of additional pathogenic rhodopsin mutations in conjunction with clinical studies are expected to provide insight into the molecular mechanism of RP and test the correlation between rhodopsin's thermal stability and RP progression in patients. PMID:23625926

  5. Thermal diffuse scattering in transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Forbes, B.D.; D' Alfonso, A.J. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Findlay, S.D. [School of Physics, Monash University, Victoria 3800 (Australia); Van Dyck, D. [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); LeBeau, J.M. [North Carolina State University, Raleigh, NC 27695-7907 (United States); Stemmer, S. [Materials Department, University of California, Santa Barbara, CA 93106-5050 (United States); Allen, L.J., E-mail: lja@unimelb.edu.au [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia)

    2011-12-15

    In conventional transmission electron microscopy, thermal scattering significantly affects the image contrast. It has been suggested that not accounting for this correctly is the main cause of the Stobbs factor, the ubiquitous, large contrast mismatch found between theory and experiment. In the case where a hard aperture is applied, we show that previous conclusions drawn from work using bright field scanning transmission electron microscopy and invoking the principle of reciprocity are reliable in the presence of thermal scattering. In the aperture-free case it has been suggested that even the most sophisticated mathematical models for thermal diffuse scattering lack in their numerical implementation, specifically that there may be issues in sampling, including that of the contrast transfer function of the objective lens. We show that these concerns can be satisfactorily overcome with modest computing resources; thermal scattering can be modelled accurately enough for the purpose of making quantitative comparison between simulation and experiment. Spatial incoherence of the source is also investigated. Neglect or inadequate handling of thermal scattering in simulation can have an appreciable effect on the predicted contrast and can be a significant contribution to the Stobbs factor problem. -- Highlights: Black-Right-Pointing-Pointer We determine the numerical requirements for accurate simulation of TDS in CTEM. Black-Right-Pointing-Pointer TDS can be simulated to high precision using the Born-Oppenheimer model. Black-Right-Pointing-Pointer Such calculations establish the contribution of TDS to the Stobbs factor problem. Black-Right-Pointing-Pointer Treating spatial incoherence using envelope functions increases image contrast. Black-Right-Pointing-Pointer Rigorous treatment of spatial incoherence significantly reduces image contrast.

  6. Thermal stability of the tokamak plasma edge

    International Nuclear Information System (INIS)

    Stacey, W.M.

    1997-01-01

    The general linear, fluid, thermal instability theory for the plasma edge has been extended. An analysis of a two-dimensional fluid model of the plasma edge has identified the importance of many previously unappreciated phenomena associated with parallel and gyroviscous forces in the presence of large radial gradients, with large radial or parallel flows, with the temperature dependence of transport coefficients, and with the coupling of temperature, flow and density perturbations. The radiative condensation effect is generalized to include a further destabilizing condensation effect associated with radial heat conduction. Representative plasma edge neutral and impurity densities are found to be capable of driving thermal instabilities in the edge transport barrier and radiative mantle, respectively. (author)

  7. Thermal stability study for candidate stainless steels of GEN IV reactors

    International Nuclear Information System (INIS)

    Simeg Veternikova, J.; Degmova, J.; Pekarcikova, M.; Simko, F.; Petriska, M.; Skarba, M.; Mikula, P.; Pupala, M.

    2016-01-01

    Highlights: • Thermal resistance of advanced stainless steels were observed at 1000 °C. • GEN IV candidate steels were confronted to classic AISI steels. • ODS AISI 316 has weaker thermal resistance than classic AISI steel. • Ferritic ODS steels and NF 709 has better thermal resistance than AISI steels. - Abstract: Candidate stainless steels for GEN IV reactors were investigated in term of thermal and corrosion stability at high temperatures. New austenitic steel (NF 709), austenitic ODS steel (ODS 316) and two ferritic ODS steels (MA 956 and MA 957) were exposed to around 1000 °C in inert argon atmosphere at pressure of ∼8 MPa. The steels were further studied in a light of vacancy defects presence by positron annihilation spectroscopy and their thermal resistance was confronted to classic AISI steels. The thermal strain supported a creation of oxide layers observed by scanning electron microscopy (SEM).

  8. Thermal stability study for candidate stainless steels of GEN IV reactors

    Energy Technology Data Exchange (ETDEWEB)

    Simeg Veternikova, J., E-mail: jana.veternikova@stuba.sk [Institute of Nuclear and Physical Engineering, Faculty of Electrical and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Degmova, J. [Institute of Nuclear and Physical Engineering, Faculty of Electrical and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Pekarcikova, M. [Institute of Materials Science, Faculty of Materials Science and Technology, Slovak University of Technology, Paulinska 16, 917 24 Trnava (Slovakia); Simko, F. [Department of Molten Salts, Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dubravska cesta 9, 845 36 Bratislava (Slovakia); Petriska, M. [Institute of Nuclear and Physical Engineering, Faculty of Electrical and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Skarba, M. [Slovak University of Technology, Vazovova 5, 812 43 Bratislava (Slovakia); Mikula, P. [Institute of Nuclear and Physical Engineering, Faculty of Electrical and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Pupala, M. [Department of Molten Salts, Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dubravska cesta 9, 845 36 Bratislava (Slovakia)

    2016-11-30

    Highlights: • Thermal resistance of advanced stainless steels were observed at 1000 °C. • GEN IV candidate steels were confronted to classic AISI steels. • ODS AISI 316 has weaker thermal resistance than classic AISI steel. • Ferritic ODS steels and NF 709 has better thermal resistance than AISI steels. - Abstract: Candidate stainless steels for GEN IV reactors were investigated in term of thermal and corrosion stability at high temperatures. New austenitic steel (NF 709), austenitic ODS steel (ODS 316) and two ferritic ODS steels (MA 956 and MA 957) were exposed to around 1000 °C in inert argon atmosphere at pressure of ∼8 MPa. The steels were further studied in a light of vacancy defects presence by positron annihilation spectroscopy and their thermal resistance was confronted to classic AISI steels. The thermal strain supported a creation of oxide layers observed by scanning electron microscopy (SEM).

  9. Stabilizing the thermal lattice Boltzmann method by spatial filtering.

    Science.gov (United States)

    Gillissen, J J J

    2016-10-01

    We propose to stabilize the thermal lattice Boltzmann method by filtering the second- and third-order moments of the collision operator. By means of the Chapman-Enskog expansion, we show that the additional numerical diffusivity diminishes in the low-wavnumber limit. To demonstrate the enhanced stability, we consider a three-dimensional thermal lattice Boltzmann system involving 33 discrete velocities. Filtering extends the linear stability of this thermal lattice Boltzmann method to 10-fold smaller transport coefficients. We further demonstrate that the filtering does not compromise the accuracy of the hydrodynamics by comparing simulation results to reference solutions for a number of standardized test cases, including natural convection in two dimensions.

  10. Thermal and mechanical stability of zeolitic imidazolate frameworks polymorphs

    Directory of Open Access Journals (Sweden)

    Lila Bouëssel du Bourg

    2014-12-01

    Full Text Available Theoretical studies on the experimental feasibility of hypothetical Zeolitic Imidazolate Frameworks (ZIFs have focused so far on relative energy of various polymorphs by energy minimization at the quantum chemical level. We present here a systematic study of stability of 18 ZIFs as a function of temperature and pressure by molecular dynamics simulations. This approach allows us to better understand the limited stability of some experimental structures upon solvent or guest removal. We also find that many of the hypothetical ZIFs proposed in the literature are not stable at room temperature. Mechanical and thermal stability criteria thus need to be considered for the prediction of new MOF structures. Finally, we predict a variety of thermal expansion behavior for ZIFs as a function of framework topology, with some materials showing large negative volume thermal expansion.

  11. Synthesis, characterization and thermal stability of solid solutions Zr (Y, Fe, MoO2

    Directory of Open Access Journals (Sweden)

    Felipe Legorreta-García

    2015-05-01

    Full Text Available The synthesis of Fe3+, Mo4+ and Y3+ fully stabilized zirconia by the nitrate/urea combustion route and thermal stability in air was investigated. The solid solution obtained was characterized by X ray diffraction (XRD, scanning electron microscopy (SEM and used the BET method for determining specific surface. The ceramic powders obtained were calcined at 1473 K in air atmosphere in order to determine their thermal stability. The scanning electron microscopy (SEM results showed a homogeneous grain surface, measuring several tens of micrometers across. The crystallographic study revealed that by this method it was successfully achieved zirconia doped with Fe3+, Mo4+ and Y3+ ions in the zirconia tetragonal monophase, even after calcinations.

  12. Synthesis, characterization and thermal stability of solid solutions Zr (Y, Fe, Mo)O {sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Legorreta-Garcia, F.; Esperanza Hernandez-Cruz, L.; Villanueva-Ibanez, M.; Flores-Gonzalez, M. A.

    2015-10-01

    The synthesis of Fe{sup 3}+, Mo{sup 4+} and Y{sup 3+} fully stabilized zirconia by the nitrate/urea combustion route and thermal stability in air was investigated. The solid solution obtained was characterized by X ray diffraction (XRD), scanning electron microscopy (SEM) and used the BET method for determining specific surface. The ceramic powders obtained were calcined at 1473 K in air atmosphere in order to determine their thermal stability. The scanning electron microscopy (SEM) results showed a homogeneous grain surface, measuring several tens of micrometers across. The crystallographic study revealed that by this method it was successfully achieved zirconia doped with Fe{sup 3+}, Mo{sup 4+} and Y{sup 3+} ions in the zirconia tetragonal monophase, even after calcinations. (Author)

  13. Thermalization Time Bounds for Pauli Stabilizer Hamiltonians

    Science.gov (United States)

    Temme, Kristan

    2017-03-01

    We prove a general lower bound to the spectral gap of the Davies generator for Hamiltonians that can be written as the sum of commuting Pauli operators. These Hamiltonians, defined on the Hilbert space of N-qubits, serve as one of the most frequently considered candidates for a self-correcting quantum memory. A spectral gap bound on the Davies generator establishes an upper limit on the life time of such a quantum memory and can be used to estimate the time until the system relaxes to thermal equilibrium when brought into contact with a thermal heat bath. The bound can be shown to behave as {λ ≥ O(N^{-1} exp(-2β overline{ɛ}))}, where {overline{ɛ}} is a generalization of the well known energy barrier for logical operators. Particularly in the low temperature regime we expect this bound to provide the correct asymptotic scaling of the gap with the system size up to a factor of N -1. Furthermore, we discuss conditions and provide scenarios where this factor can be removed and a constant lower bound can be proven.

  14. Problem of the lithium peroxide thermal stability

    International Nuclear Information System (INIS)

    Nefedov, R A; Ferapontov, Yu A; Kozlova, N P

    2016-01-01

    The behavior of lithium peroxide and lithium peroxide monohydrate samples under heating in atmospheric air was studied by the method of thermogravimetric analysis (TGA) and differential thermal analysis (DTA). It was found that in the temperature range of 32°C to 82°C the interaction of lithium peroxides and steam with the formation of lithium peroxide monohydrate occurs, which was confirmed chemically and by X-ray Single-qualitative analysis. It was experimentally found that lithium peroxide starts to decompose into the lithium oxide and oxygen in the temperature range of 340 ÷ 348°C. It was established that the resulting thermal decomposition of lithium oxide, lithium peroxide at the temperature of 422°C melts with lithium carbonate eutecticly. The manifestation of polymorphism was not marked(seen or noticed) under the heating of studied samples of lithium peroxide and lithium peroxide monohydrate in the temperature range of 25°C ÷ 34°C. (paper)

  15. Method for enhancing the thermal stability of ionic compounds

    DEFF Research Database (Denmark)

    2013-01-01

    This invention relates to a method for enhancing the thermal stability of ionic compounds including ionic liquids, by immobilization on porous solid support materials having a pore diameter of between about 20-200 AA, wherein the solid support does not have a pore size of 90 AA.......This invention relates to a method for enhancing the thermal stability of ionic compounds including ionic liquids, by immobilization on porous solid support materials having a pore diameter of between about 20-200 AA, wherein the solid support does not have a pore size of 90 AA....

  16. Relationship between mechanical characteristics and thermal shock stability of refractories

    International Nuclear Information System (INIS)

    Volkov-Husovic, T.; Raic, K.

    2003-01-01

    Thermal stability of the refractory material with the content of 60 % Al 2 O 3 was investigated. Water quench test (JUS.B.D8.319) was applied as experimental method for thermal stability testing. Damage of porous materials is commonly related to a modification of strength that is mostly a reduction. This is linked with characteristics related to pore space. Mechanical characteristics are considered such as compressive strength, dynamic modulus of elasticity and resistance parameters resulting from resonance frequency measurements, as well as ultrasonic velocity. (Original)

  17. Degradation Behavior of Thermal Stabilized Polyacrylonitrile Fibers

    Directory of Open Access Journals (Sweden)

    LEI Shuai

    2017-05-01

    Full Text Available In the temperature range of 300-800℃, 40%-50% of the mass lost during the processing of polyacrylonitrile based carbon fiber (PANCF. Understanding the degradation behavior will be valuable in understanding the formation mechanism of pseudo-graphite structure, and providing theoretic basis for producing high performance carbon fiber and increasing the carbonization yield. The simulation of the degradation progress was carried out on the thermogravimetric analyzer (TGA, the results show that there are two degradation steps for PAN fiber stabilized in air, and controlled by cyclization coefficient and oxygen content. The cyclization coefficient and oxygen content are effective to the density of carbon fiber by influencing the degradation behavior, which cause defects in the fiber. The higher cyclization coefficient leads to form less structural defects and higher density of the fiber; on the contrary, the higher oxygen content leads to form more structural defects and lower density of the fiber.

  18. Thermal stability of polyvinyl alcohol/nanocrystalline cellulose composites.

    Science.gov (United States)

    Voronova, Marina I; Surov, Oleg V; Guseinov, Sabir S; Barannikov, Vladimir P; Zakharov, Anatoly G

    2015-10-05

    Thermal stability of polyvinyl alcohol/cellulose nanocrystals (PVA/CNCs) composites prepared with solution casting technique was studied. The PVA/CNCs composites were characterized by Fourier transform infrared spectrometry, X-ray diffraction, differential scanning calorimeter (DSC) and thermogravimetric (TG) analysis. Due to the presence of CNCs nanoparticles, thermal degradation of the composites occurs at much higher temperatures compared to that of the neat PVA. Thermal stability of the PVA/CNCs composites is maximally enhanced with CNCs content of 8-12 wt%. Some thermal degradation products of the PVA/CNCs composites were identified by mass spectrometric analysis. TG measurements with synchronous recording of mass spectra revealed that the thermal degradation of both CNCs and PVA in the composites with CNCs content of 8-12 wt% occurs simultaneously at a much higher temperature than that of CNCs or the neat PVA. However, with increasing CNCs content more than 12 wt% the thermal stability of the composites decreases. In this case, the degradation of CNCs comes first followed by the degradation of PVA. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Theoretical bases on thermal stability of layered metallic systems

    International Nuclear Information System (INIS)

    Kadyrzhanov, K.K.; Rusakov, V.S.; Turkebaev, T.Eh.; Zhankadamova, A.M.; Ensebaeva, M.Z.

    2003-01-01

    The paper is dedicated to implementation of the theoretical bases for layered metallic systems thermal stabilization. The theory is based on the stabilization mechanism expense of the intermediate two-phase field formation. As parameters of calculated model are coefficients of mutual diffusion and inclusions sizes of generated phases in two-phase fields. The stabilization time dependence for beryllium-iron (Be (1.1 μm)-Fe(5.5 μm)) layered system from iron and beryllium diffusion coefficients, and inclusions sizes is shown as an example. Conclusion about possible mechanisms change at transition from microscopic consideration to the nano-crystal physics level is given

  20. Fabrication, thermal properties and thermal stabilities of microencapsulated n-alkane with poly(lauryl methacrylate) as shell

    International Nuclear Information System (INIS)

    Qiu, Xiaolin; Lu, Lixin; Wang, Ju; Tang, Guoyi; Song, Guolin

    2015-01-01

    Highlights: • Microencapsulation of octadecane and paraffin by crosslinked poly(lauryl methacrylate). • Octadecane microcapsules have a melting enthalpy of about 118 J g −1 . • Weight loss temperatures of the microcapsules were increased by 67 °C and 28 °C. • Phase change enthalpies decreased by around 10 wt% after 500 thermal cycles. • Foams with microcapsules can be applied for passive temperature control. - Abstract: Microencapsulation of n-octadecane or paraffin with poly(lauryl methacrylate) (PLMA) shell was performed by a suspension-like polymerization. The polymer shell was crosslinked by pentaerythritol tetraacrylate (PETRA). The surface morphologies of microcapsules were investigated by scanning electron microscopy (SEM). Phase change properties, thermal reliabilities and thermal stabilities of microcapsules were determined by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The n-octadecane microcapsule exhibits higher melting enthalpy (118.0 J g −1 ) and crystallization enthalpy (108.3 J g −1 ) compared with the paraffin microcapsule. The thermal resistant temperatures were enhanced by more than 25 °C when n-alkanes were microencapsulated by PLMA. The PCM contents of microcapsules decreased by less than 4 wt% and 6 wt% after 500 and 1000 thermal cycles, respectively. Heat-up experiments indicated that microcapsule-treated foams exhibited upgraded thermal regulation capacities. Consequently, microencapsulated n-octadecane or paraffin with PLMA as shell possesses good potentials for heat storage and thermal regulation.

  1. Fabrication, thermal properties and thermal stabilities of microencapsulated n-alkane with poly(lauryl methacrylate) as shell

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Xiaolin, E-mail: shirleyqiu2009@gmail.com [Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology, School of Mechanical Engineering, Jiangnan University, Wuxi 214122 (China); Lu, Lixin; Wang, Ju [Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology, School of Mechanical Engineering, Jiangnan University, Wuxi 214122 (China); Tang, Guoyi [Advanced Materials Institute and Clearer Production Key Laboratory, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Key Laboratory of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Haidian District, Beijing 100084 (China); Song, Guolin [Advanced Materials Institute and Clearer Production Key Laboratory, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China)

    2015-11-20

    Highlights: • Microencapsulation of octadecane and paraffin by crosslinked poly(lauryl methacrylate). • Octadecane microcapsules have a melting enthalpy of about 118 J g{sup −1}. • Weight loss temperatures of the microcapsules were increased by 67 °C and 28 °C. • Phase change enthalpies decreased by around 10 wt% after 500 thermal cycles. • Foams with microcapsules can be applied for passive temperature control. - Abstract: Microencapsulation of n-octadecane or paraffin with poly(lauryl methacrylate) (PLMA) shell was performed by a suspension-like polymerization. The polymer shell was crosslinked by pentaerythritol tetraacrylate (PETRA). The surface morphologies of microcapsules were investigated by scanning electron microscopy (SEM). Phase change properties, thermal reliabilities and thermal stabilities of microcapsules were determined by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The n-octadecane microcapsule exhibits higher melting enthalpy (118.0 J g{sup −1}) and crystallization enthalpy (108.3 J g{sup −1}) compared with the paraffin microcapsule. The thermal resistant temperatures were enhanced by more than 25 °C when n-alkanes were microencapsulated by PLMA. The PCM contents of microcapsules decreased by less than 4 wt% and 6 wt% after 500 and 1000 thermal cycles, respectively. Heat-up experiments indicated that microcapsule-treated foams exhibited upgraded thermal regulation capacities. Consequently, microencapsulated n-octadecane or paraffin with PLMA as shell possesses good potentials for heat storage and thermal regulation.

  2. Thermal stability of substitutional ag in CdTe

    NARCIS (Netherlands)

    Jahn, SG; Hofsass, H; Restle, M; Ronning, C; Quintel, H; BharuthRam, K; Wahl, U

    The thermal stability of substitutional Ag in CdTe was deduced from lattice location measurements at different temperatures. Substitutional Ag probe atoms were generated via transmutation doping from radioactive Cd isotopes. The lattice sites of Ag isotopes were determined by measuring the

  3. Preparation and thermal stability of nickel nanowires via self ...

    Indian Academy of Sciences (India)

    Administrator

    Nickel nanowires; magnetic field; self-assembly; thermal stability. 1. Introduction ... vapour-phase techniques mainly include methods such as chemical ... 2.1 Materials and methods .... sum up, the colour change of NiO may be caused by the.

  4. Strength and thermal stability of fiber reinforced plastic composites ...

    African Journals Online (AJOL)

    Therefore, the strength properties and thermal stability of plastic composites reinforced with rattan fibers were investigated in this work. Particles of rattan species (Eremospatha macrocarpa (EM) and Laccosperma secundiflorum (LS)) were blended with High-Density Polyethylene (HDPE) to produce fiber reinforced plastic ...

  5. Morphology, thermal, electrical and electrochemical stability of nano

    Indian Academy of Sciences (India)

    In the present work, an attempt has been made to develop nano aluminium oxide (Al2O3)-filled polyvinyl alcohol (PVA) composite gel electrolytes. Surface morphological studies, thermal behaviour, electrochemical stability and electrical characterization of these composite gel electrolytes have been performed. An increase ...

  6. Thermal stability of liquid antioxidative extracts from pomegranate peel

    Science.gov (United States)

    This research was carried out to assess the potential of using the natural antioxidants in pomegranate peel extracts as replacement for synthetic antioxidants. As a result the thermal stability of pomegranate peel extract products during sterilization and storage, and its effect on industrial, color...

  7. Thermal properties and stabilities of polymer thin films

    International Nuclear Information System (INIS)

    Kanaya, Toshiji; Kawashima, Kazuko; Inoue, Rintaro; Miyazaki, Tsukasa

    2009-01-01

    Recent extensive studies have revealed that polymer thin films showed very interesting but unusual thermal properties and stabilities. In the article we show that X-ray reflectivity and neutron reflectivity are very powerful tools to study the anomalous properties of polymer thin films. (author)

  8. Can green solvents be alternatives for thermal stabilization of collagen?

    Science.gov (United States)

    Mehta, Ami; Rao, J Raghava; Fathima, Nishter Nishad

    2014-08-01

    "Go Green" campaign is gaining light for various industrial applications where water consumption needs to be reduced. To resolve this, industries have adopted usage of green, organic solvents, as an alternative to water. For leather making, tanning industry consumes gallons of water. Therefore, for adopting green solvents in leather making, it is necessary to evaluate its influence on type I collagen, the major protein present in the skin matrix. The thermal stability of collagen from rat tail tendon fiber (RTT) treated with seven green solvents namely, ethanol, ethyl lactate, ethyl acetate, propylene carbonate, propylene glycol, polyethylene glycol-200 and heptane was determined using differential scanning calorimetry (DSC). Crosslinking efficiency of basic chromium sulfate and wattle on RTT in green solvents was determined. DSC thermograms show increase in thermal stability of RTT collagen against heat with green solvents (>78°C) compared to water (63°C). In the presence of crosslinkers, RTT demonstrated thermal stability >100°C in some green solvents, resulting in increased intermolecular forces between collagen, solvent and crosslinkers. The significant improvement in thermal stability of collagen potentiates the capability of green solvents as an alternative for water. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Lanthanide phosphonates: Synthesis, thermal stability and magnetic characterization

    Energy Technology Data Exchange (ETDEWEB)

    Amghouz, Z., E-mail: amghouz.uo@uniovi.es [Departamentos de Quimica Fisica y Analitica y Quimica Organica e Inorganica, Universidad de Oviedo - CINN, 33006 Oviedo (Spain); Garcia, J.R.; Garcia-Granda, S. [Departamentos de Quimica Fisica y Analitica y Quimica Organica e Inorganica, Universidad de Oviedo - CINN, 33006 Oviedo (Spain); Clearfield, A. [Department of Chemistry, Texas A and M University, College Station, TX 77842-3012 (United States); Rodriguez Fernandez, J.; Pedro, I. de [CITIMAC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander (Spain); Blanco, J.A. [Departamento de Fisica, Universidad de Oviedo, 33007 Oviedo (Spain)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Report of the complete series of lanthanide 1,4-phenylbis(phosphonate). Black-Right-Pointing-Pointer Synthesis under conventional hydrothermal synthesis or microwave-assisted hydrothermal synthesis. Black-Right-Pointing-Pointer Cation size is the key factor for the structural and particles size variations. Black-Right-Pointing-Pointer Thermal behaviour is characterized by unusual very high thermal stability. - Abstract: Series of novel organic-inorganic hybrids materials based on trivalent lanthanides (Ln = Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) and 1,4-phenylbis(phosphonate) obtained under hydrothermal conditions either by oven heat or microwave irradiation. The anhydrous compounds containing La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Ho, are isostructural. However, the compounds based on Y, Er, Tm, Yb, and Lu are hydrated and their structures have not yet been solved. The series of compounds are characterized by PXRD, TEM, SEM-EDX and thermal analyses (TG-MS and DSC). TEM study show a variable particles size with a minimum mean-particle size of ca. 30 nm. These compounds exhibit unusual very high thermal stability. The size of particles and the thermal stability are depending on lanthanide(III) cation features. All the investigated materials show paramagnetic behaviour. The magnetic susceptibility data follow a Curie-Weiss laws with paramagnetic effective moments in good agreement with those expected for Ln{sup 3+} free ions.

  10. Thermal stability of biodiesel and its blends: A review

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Siddharth; Sharma, M.P. [Biofuel Research Laboratory, Alternate Hydro Energy Centre, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667 (India)

    2011-01-15

    The vegetable oil, fats and their biodiesel suffer with the drawback of deterioration of its quality during long term storage unlike petroleum diesel due to large number of environmental and other factors making the fuel stability and quality questionable. There are various types of stabilities like oxidation, storage and thermal, playing key roles in making the fuel unstable. The present paper is an attempt to review the work done so far on the thermal stability of biodiesel and their blends with diesel under different conditions. The mechanism of thermal deterioration of vegetable oils, various methods of stability measurement including a new proposed method based on Karl Fischer coulometer, an alternative to conventional Rancimat test has been discussed. No correlations have been found in the literature among the results of various methods used. The effect of antioxidants on the stability parameters has also been discussed. TGA/DTA has been found as an effective method to check the deterioration of oil with respect to temperature using activation energy and order of reaction as the parameter to monitor the deterioration of oil. (author)

  11. Materials Compositions for Lithium Ion Batteries with Extended Thermal Stability

    Science.gov (United States)

    Kalaga, Kaushik

    Advancements in portable electronics have generated a pronounced demand for rechargeable energy storage devices with superior capacity and reliability. Lithium ion batteries (LIBs) have evolved as the primary choice of portable power for several such applications. While multiple variations have been developed, safety concerns of commercial technologies limit them to atmospheric temperature operability. With several niche markets such as aerospace, defense and oil & gas demanding energy storage at elevated temperatures, there is a renewed interest in developing rechargeable batteries that could survive temperatures beyond 100°C. Instability of critical battery components towards extreme thermal and electrochemical conditions limit their usability at high temperatures. This study deals with developing material configurations for LIB components to stabilize them at such temperatures. Flammable organic solvent based electrolytes and low melting polymer based separators have been identified as the primary bottleneck for LIBs to survive increasing temperature. Furthermore, thermally activated degradation processes in oxide based electrodes have been identified as the reason for their limited lifetime. A quasi-solid composite comprising of room temperature ionic liquids (RTILs) and Clay was developed as an electrolyte/separator hybrid and tested to be stable up to 120°C. These composites facilitate complete reversible Li intercalation in lithium titanate (LTO) with a stable capacity of 120 mAh g-1 for several cycles of charge and discharge while simultaneously resisting severe thermal conditions. Modified phosphate based electrodes were introduced as a reliable alternative for operability at high temperatures in this study. These systems were shown to deliver stable reversible capacity for numerous charge/discharge cycles at elevated temperatures. Higher lithium intercalation potential of the developed cathode materials makes them interesting candidates for high voltage

  12. Monte Carlo Transport for Electron Thermal Transport

    Science.gov (United States)

    Chenhall, Jeffrey; Cao, Duc; Moses, Gregory

    2015-11-01

    The iSNB (implicit Schurtz Nicolai Busquet multigroup electron thermal transport method of Cao et al. is adapted into a Monte Carlo transport method in order to better model the effects of non-local behavior. The end goal is a hybrid transport-diffusion method that combines Monte Carlo Transport with a discrete diffusion Monte Carlo (DDMC). The hybrid method will combine the efficiency of a diffusion method in short mean free path regions with the accuracy of a transport method in long mean free path regions. The Monte Carlo nature of the approach allows the algorithm to be massively parallelized. Work to date on the method will be presented. This work was supported by Sandia National Laboratory - Albuquerque and the University of Rochester Laboratory for Laser Energetics.

  13. Optical Thermal Characterization Enables High-Performance Electronics Applications

    Energy Technology Data Exchange (ETDEWEB)

    2016-02-01

    NREL developed a modeling and experimental strategy to characterize thermal performance of materials. The technique provides critical data on thermal properties with relevance for electronics packaging applications. Thermal contact resistance and bulk thermal conductivity were characterized for new high-performance materials such as thermoplastics, boron-nitride nanosheets, copper nanowires, and atomically bonded layers. The technique is an important tool for developing designs and materials that enable power electronics packaging with small footprint, high power density, and low cost for numerous applications.

  14. Improved thermal stability and wettability behavior of thermoplastic polyurethane / barium metaborate composites

    International Nuclear Information System (INIS)

    Baştürka, Emre; Madakbaş, Seyfullah; Kahraman, Memet Vezir

    2016-01-01

    In this paper, it was targeted to the enhance thermal stability and wettability behavior of thermoplastic polyurethane (TPU) by adding barium metaborate. TPU-Barium metaborate composites were prepared by adding various proportions of barium metaborate to TPU. The chemical structures of the composites were characterised by fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis. All prepared composites have extremely high Tg and thermal stability as determined from DSC and TGA analysis. All composite materials have the Tg ranging from 15 to 35 °C. The surface morphologies of the composites were investigated by a scanning electron microscopy. Mechanical properties of the samples were characterized with stress-strain test. Hydrophobicity of the samples was determined by the contact angle measurements. The obtained results proved that thermal, hydrophobic and mechanical properties were improved. (author)

  15. Improved thermal stability and wettability behavior of thermoplastic polyurethane / barium metaborate composites

    Energy Technology Data Exchange (ETDEWEB)

    Baştürka, Emre; Madakbaş, Seyfullah; Kahraman, Memet Vezir, E-mail: smadakbas@marmara.edu.tr [Department of Chemistry, Marmara University, Istanbul (Turkey)

    2016-03-15

    In this paper, it was targeted to the enhance thermal stability and wettability behavior of thermoplastic polyurethane (TPU) by adding barium metaborate. TPU-Barium metaborate composites were prepared by adding various proportions of barium metaborate to TPU. The chemical structures of the composites were characterised by fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis. All prepared composites have extremely high Tg and thermal stability as determined from DSC and TGA analysis. All composite materials have the Tg ranging from 15 to 35 °C. The surface morphologies of the composites were investigated by a scanning electron microscopy. Mechanical properties of the samples were characterized with stress-strain test. Hydrophobicity of the samples was determined by the contact angle measurements. The obtained results proved that thermal, hydrophobic and mechanical properties were improved. (author)

  16. High-temperature stability of yttria-stabilized zirconia thermal barrier ...

    Indian Academy of Sciences (India)

    The coatings before and after IR heating were investigated by scanning electron microscopy, X-ray diffraction, electron probe microanalysis, microhardness and residual stress measurements in order to understand the effect of thermal shock on the properties of the TBC. On account of these high-temperature properties, ...

  17. Modifications to improve entrance slit thermal stability for grasshopper monochromators

    Science.gov (United States)

    Wallace, Daniel J.; Rogers, Gregory C.; Crossley, Sherry L.

    1994-08-01

    As new monochromators are designed for high-flux storage rings, computer modeling and thermal engineering can be done to process increased heat loads and achieve mechanical stability. Several older monochromators, such as the Mark 2 and Mark 5 Grasshopper monochromators, which were designed in 1974, have thermal instabilities in their entrance slit mechanisms. The Grasshoppers operating with narrow slits experience closure of the entrance slit from thermal expansion. In extreme cases, the thermal expansion of the precision components has caused permanent mechanical damage, leaving the slit uncalibrated and/or inoperable. For the Mark 2 and Mark 5 Grasshopper monochromators at the Synchrotron Radiation Center, the original 440 stainless steel entrance slit jaws were retrofitted with an Invar (low expansion Fe, Ni alloy) slit jaw. To transfer the heat from the critical components, two flexible heat straps of Cu were attached. These changes allow safe operation with a 10 μm entrance slit width where the previous limit was 30 μm. After an initial 2 min equilibration, the slit remains stable to 10%, with 100 mA of beam current. Additional improvements in slit thermal stability are planned for a third Grasshopper.

  18. Thermal Stability and Magnetic Properties of Polyvinylidene Fluoride/Magnetite Nanocomposites

    OpenAIRE

    Ouyang, Zen-Wei; Chen, Erh-Chiang; Wu, Tzong-Ming

    2015-01-01

    This work describes the thermal stability and magnetic properties of polyvinylidene fluoride (PVDF)/magnetite nanocomposites fabricated using the solution mixing technique. The image of transmission electron microscopy for PVDF/magnetite nanocomposites reveals that the 13 nm magnetite nanoparticles are well distributed in PVDF matrix. The electroactive β-phase and piezoelectric responses of PVDF/magnetite nanocomposites are increased as the loading of magnetite nanoparticles increases. The pi...

  19. Thermal stability of homo- and copolymers of vinyl fluoride

    International Nuclear Information System (INIS)

    Raucher, D.; Levy, M.

    1979-01-01

    The thermal stability of poly(vinyl fluoride)(PVF) was studied by thermal gravimetry and mass spectrometry (TGA and TGA-MS). In low-molecular-weight polymers a two-step decomposition pattern was observed. It consisted of the dehydrofluorination to a polyene chain followed by decomposition of the resulting polyene at higher temperatures. Copolymers of vinyl fluoride-vinyl acetate (VF-VAc) and vinyl fluoride-vinyl chloride (VF-VCl) showed a simultaneous evolution of hydrofluoric acid and acetic acid and hydrofluoric acid and hydrochloric acid, respectively. This suggests that after the elimination of the weakest link a spontaneous elimination of neighboring HF molecules takes place

  20. Thermal stability of intermediate band behavior in Ti implanted Si

    Energy Technology Data Exchange (ETDEWEB)

    Olea, J.; Pastor, D.; Martil, I.; Gonzalez-Diaz, G. [Dpto. De Fisica Aplicada III (Electricidad y Electronica), Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain)

    2010-11-15

    Ti implantation in Si with very high doses has been performed. Subsequent Pulsed Laser Melting (PLM) annealing produces good crystalline lattice with electrical transport properties that are well explained by the Intermediate Band (IB) theory. Thermal stability of this new material is analyzed by means of isochronal annealing in thermodynamic equilibrium conditions at increasing temperature. A progressive deactivation of the IB behavior is shown during thermal annealing, and structural and electrical measurements are reported in order to find out the origin of this result. (author)

  1. Phenols and aromatic amines as thermal stabilizers in polyolefin processing

    Czech Academy of Sciences Publication Activity Database

    Pospíšil, Jan; Habicher, W. D.; Al-Malaika, S.; Zweifel, H.; Nešpůrek, Stanislav

    2001-01-01

    Roč. 176, - (2001), s. 55-63 ISSN 1022-1360. [International Conference on Polymer Modification, Degradation and Stabilization /1./. Palermo , 03.09.2000-07.09.2000] R&D Projects: GA AV ČR IAA1050901; GA MŠk ME 184; GA MŠk ME 372; GA AV ČR KSK4050111 Institutional research plan: CEZ:AV0Z4050913 Keywords : thermal stabilizers * phenols * aromatic amines Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.634, year: 2001

  2. The thermal stability of the carbon-palladium films for hydrogen sensor applications

    Science.gov (United States)

    Rymarczyk, Joanna; Czerwosz, ElŻbieta; Diduszko, Ryszard; Kozłowski, Mirosław

    2017-08-01

    The thermal stability of two types of C-Pd films prepared in PVD process were studied. These films are composed of Pd nanograins embedded in a multiphase carbonaceous matrix. These films were distinguished by Pd content. These films were annealed in a range of temperatures 50÷1000°C. The structural, topographical and molecular changes were studied by scanning electron microscopy (SEM), infrared spectroscopy (FTIR) and X-ray diffraction (XRD) methods. The results show that investigated films are thermally stable up to 200°C.

  3. Thermal stability of bubble domains in ferromagnetic discs

    Energy Technology Data Exchange (ETDEWEB)

    Hrkac, G [University of Sheffield, Engineering Materials, Mappin Street, Sheffield S1 3JD (United Kingdom) ; Bance, S [University of Sheffield, Engineering Materials, Mappin Street, Sheffield S1 3JD (United Kingdom) ; Goncharov, A [University of Sheffield, Engineering Materials, Mappin Street, Sheffield S1 3JD (United Kingdom) ; Schrefl, T [University of Sheffield, Engineering Materials, Mappin Street, Sheffield S1 3JD (United Kingdom) ; Suess, D [Vienna University of Technology, Wiedner Hauptstr. 8-10e, A-1040 Vienna (Austria)

    2007-05-07

    The transition and thermal stability of disc-shaped ferromagnetic particles at the temperature of T = 300 K with a uniaxial anisotropy along the symmetry axis from a bi-domain to a single domain state has been studied. The nudge elastic band method was used to map the energy landscape and to calculate the energy barrier between the transition states. For single FePt disc-shaped particles with perpendicular anisotropy three transition configurations have been found: single domain, stripe- and stable bubble domains at zero applied field. The single domain configuration along the positive anisotropy axis is reached by an annihilation process of the domain wall and the all-down state by a complex domain expansion process. Magnetization configurations in two interacting discs show an increase in thermal stability compared with single disc systems, which is attributed to the interacting magnetostatic energy between the two particles.

  4. Thermal stability of poly(3-hydroxybutyrate)/vegetable fiber composites

    Science.gov (United States)

    Cipriano, Pâmela Bento; de Sá, Mayelli Dantas; Andrade, André L. Simões; de Carvalho, Laura Hecker; Canedo, Eduardo Luis

    2015-05-01

    The present work deals with the thermal stability during and after processing of composites of poly(3-hydroxybutyrate) (PHB) - a fully biodegradable semi-crystalline thermoplastic obtained from renewable resources through low-impact biotechnological process, biocompatible and non-toxic - and vegetable fiber from the fruit (coconut) of babassu palm tree. PHB/babassu composites with 0, 5, 10 and 20% w/w load were prepared in a laboratory internal mixer. Two fractions of the mesocarp of babassu with different particle sizes were compounded with PHB and test specimens molded by compression. The effect of loading level and processing conditions on torque, temperature and mechanical energy dissipation were studied using a new engineering model. It was found that PHB degrades during processing at temperatures slightly above the melting point. To minimize thermal degradation stabilizer and chain extender additives were incorporated, with mixed results. These findings were confirmed by the dependence of the melt flow rate on the processing temperature.

  5. Production for high thermal stability NdFeB magnets

    Energy Technology Data Exchange (ETDEWEB)

    Yu, L.Q. [College of Physics Science and Technology, China University of Petroleum (East China), Dongying 257061, Shandong Province (China)], E-mail: iyy2000@163.com; Zhang, J.; Hu, S.Q.; Han, Z.D. [College of Physics Science and Technology, China University of Petroleum (East China), Dongying 257061, Shandong Province (China); Yan, M. [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China)

    2008-04-15

    To improve sintered NdFeB magnets' thermal stability and magnetic properties, combined addition of elements Cu and Gd was investigated. It was found that with Gd addition increase to 1.0%, the temperature coefficient {alpha} improved from -0.15 to -0.05%/deg. C (maximum working temperature 120 deg. C), but the remanence and the maximum energy product linearly decreased. With addition of Cu in Gd-containing magnets the intrinsic coercivity increased greatly, and the remanence increased also because of their density improvement, and optimum Cu content was achieved at 0.2%. Microstructure analysis showed that most of the Cu distributed at grain boundaries and led to clear and smooth morphologies. Magnets with high thermal stability {alpha}=-0.05%/deg. C and magnetic properties were obtained with addition of Gd=0.8% and Cu=0.2%.

  6. Thermal Stabilization of Enzymes Immobilized within Carbon Paste Electrodes.

    Science.gov (United States)

    Wang, J; Liu, J; Cepra, G

    1997-08-01

    In this note we report on the remarkable thermal stabilization of enzymes immobilized in carbon paste electrodes. Amperometric biosensors are shown for the first time to withstand a prolonged high-temperature (>50 °C) stress. Nearly full activity of glucose oxidase is retained over periods of up to 4 months of thermal stress at 60-80 °C. Dramatic improvements in the thermostability are observed for polyphenol oxidase, lactate oxidase, alcohol oxidase, horseradish peroxidase, and amino acid oxidase. Such resistance to heat-induced denaturation is attributed to the conformational rigidity of these biocatalysts within the highly hydrophobic (mineral oil or silicone grease) pasting liquid. While no chemical stabilizer is needed for attaining such protective action, it appears that low humidity (i.e., low water content) is essential for minimizing the protein mobility. Besides their implications for electrochemical biosensors, such observations should lead to a new generation of thermoresistant enzyme reactors based on nonpolar semisolid supports.

  7. Thermal Stability and Proton Conductivity of Rare Earth Orthophosphate Hydrates

    DEFF Research Database (Denmark)

    Anfimova, Tatiana; Li, Qingfeng; Jensen, Jens Oluf

    2014-01-01

    as the rhabdophane structure is preserved. The bound hydrate water is accommodated in the rhabdophane structure and is stable at temperatures of up to 650 oC. The thermal stability of the hydrate water and the phosphate structure are of significance for the proton conductivity. The LaPO4·0.6H2O and NdPO4•0.5H2O......Hydrated orthophosphate powders of three rare earth metals, lanthanum, neodymium and gadolinium, were prepared and studied as potential proton conducting materials for intermediate temperature electrochemical applications. The phosphates undergo a transformation from the rhabdophane structure...... to the monazite structure upon dehydration. The thermal stability of the hydrate is studied and found to contain water of two types, physically adsorbed and structurally bound hydrate water. The adsorbed water is correlated to the specific surface area and can be reversibly recovered when dehydrated as long...

  8. Thermal stability of bubble domains in ferromagnetic discs

    International Nuclear Information System (INIS)

    Hrkac, G; Bance, S; Goncharov, A; Schrefl, T; Suess, D

    2007-01-01

    The transition and thermal stability of disc-shaped ferromagnetic particles at the temperature of T = 300 K with a uniaxial anisotropy along the symmetry axis from a bi-domain to a single domain state has been studied. The nudge elastic band method was used to map the energy landscape and to calculate the energy barrier between the transition states. For single FePt disc-shaped particles with perpendicular anisotropy three transition configurations have been found: single domain, stripe- and stable bubble domains at zero applied field. The single domain configuration along the positive anisotropy axis is reached by an annihilation process of the domain wall and the all-down state by a complex domain expansion process. Magnetization configurations in two interacting discs show an increase in thermal stability compared with single disc systems, which is attributed to the interacting magnetostatic energy between the two particles

  9. Temperature-dependent thermal conductivity of flexible yttria-stabilized zirconia substrate via 3ω technique

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Shivkant; Yarali, Milad; Mavrokefalos, Anastassios [Department of Mechanical Engineering, University of Houston, Houston, TX (United States); Shervin, Shahab [Materials Science and Engineering Program, University of Houston, Houston, TX (United States); Venkateswaran, Venkat; Olenick, Kathy; Olenick, John A. [ENrG Inc., Buffalo, NY (United States); Ryou, Jae-Hyun [Department of Mechanical Engineering, University of Houston, Houston, TX (United States); Materials Science and Engineering Program, University of Houston, Houston, TX (United States); Texas Center for Superconductivity, University of Houston (TcSUH), Houston, TX (United States)

    2017-10-15

    Thermal management in flexible electronic has proven to be challenging thereby limiting the development of flexible devices with high power densities. To truly enable the technological implementation of such devices, it is imperative to develop highly thermally conducting flexible substrates that are fully compatible with large-scale fabrication. Here, we present the thermal conductivity of state-of-the-art flexible yttria-stabilized zirconia (YSZ) substrates measured using the 3ω technique, which is already commercially manufactured via roll-to-roll technique. We observe that increasing the grain size increases the thermal conductivity of the flexible 3 mol.% YSZ, while the flexibility and transparency of the sample are hardly affected by the grain size enlargement. We exhibit thermal conductivity values of up to 4.16 Wm{sup -1}K {sup -1} that is at least 4 times higher than state-of-the-art polymeric flexible substrates. Phonon-hopping model (PHM) for granular material was used to fit the measured thermal conductivity and accurately define the thermal transport mechanism. Our results show that through grain size optimization, YSZ flexible substrates can be realized as flexible substrates, that pave new avenues for future novel application in flexible electronics through the utilization of both their ceramic structural flexibility and high heat dissipating capability. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Mechanics and thermal management of stretchable inorganic electronics.

    Science.gov (United States)

    Song, Jizhou; Feng, Xue; Huang, Yonggang

    2016-03-01

    Stretchable electronics enables lots of novel applications ranging from wearable electronics, curvilinear electronics to bio-integrated therapeutic devices that are not possible through conventional electronics that is rigid and flat in nature. One effective strategy to realize stretchable electronics exploits the design of inorganic semiconductor material in a stretchable format on an elastomeric substrate. In this review, we summarize the advances in mechanics and thermal management of stretchable electronics based on inorganic semiconductor materials. The mechanics and thermal models are very helpful in understanding the underlying physics associated with these systems, and they also provide design guidelines for the development of stretchable inorganic electronics.

  11. Mechanics and thermal management of stretchable inorganic electronics

    Science.gov (United States)

    Song, Jizhou; Feng, Xue; Huang, Yonggang

    2016-01-01

    Stretchable electronics enables lots of novel applications ranging from wearable electronics, curvilinear electronics to bio-integrated therapeutic devices that are not possible through conventional electronics that is rigid and flat in nature. One effective strategy to realize stretchable electronics exploits the design of inorganic semiconductor material in a stretchable format on an elastomeric substrate. In this review, we summarize the advances in mechanics and thermal management of stretchable electronics based on inorganic semiconductor materials. The mechanics and thermal models are very helpful in understanding the underlying physics associated with these systems, and they also provide design guidelines for the development of stretchable inorganic electronics. PMID:27547485

  12. Advanced materials for thermal management of electronic packaging

    CERN Document Server

    Tong, Xingcun Colin

    2011-01-01

    The need for advanced thermal management materials in electronic packaging has been widely recognized as thermal challenges become barriers to the electronic industry's ability to provide continued improvements in device and system performance. With increased performance requirements for smaller, more capable, and more efficient electronic power devices, systems ranging from active electronically scanned radar arrays to web servers all require components that can dissipate heat efficiently. This requires that the materials have high capability of dissipating heat and maintaining compatibility

  13. Co-evaporation of fluoropolymer additives for improved thermal stability of organic semiconductors

    Science.gov (United States)

    Price, Jared S.; Wang, Baomin; Grede, Alex J.; Shen, Yufei; Giebink, Noel C.

    2017-08-01

    Reliability remains an ongoing challenge for organic light emitting diodes (OLEDs) as they expand in the marketplace. The ability to withstand operation and storage at elevated temperature is particularly important in this context, not only because of the inverse dependence of OLED lifetime on temperature, but also because high thermal stability is fundamentally important for high power/brightness operation as well as applications such as automotive lighting, where interior car temperatures often exceed the ambient by 50 °C or more. Here, we present a strategy to significantly increase the thermal stability of small molecule OLEDs by co-depositing an amorphous fluoropolymer, Teflon AF, to prevent catastrophic failure at elevated temperatures. Using this approach, we demonstrate that the thermal breakdown limit of common hole transport materials can be increased from typical temperatures of ˜100 °C to more than 200 °C while simultaneously improving their electrical transport properties. Similar thermal stability enhancements are demonstrated in simple bilayer OLEDs. These results point toward a general approach to engineer morphologically-stable organic electronic devices that are capable of operating or being stored in extreme thermal environments.

  14. Thermal precipitation fluorescence assay for protein stability screening.

    Science.gov (United States)

    Fan, Junping; Huang, Bo; Wang, Xianping; Zhang, Xuejun C

    2011-09-01

    A simple and reliable method of protein stability assessment is desirable for high throughput expression screening of recombinant proteins. Here we described an assay termed thermal precipitation fluorescence (TPF) which can be used to compare thermal stabilities of recombinant protein samples directly from cell lysate supernatants. In this assay, target membrane proteins are expressed as recombinant fusions with a green fluorescence protein tag and solubilized with detergent, and the fluorescence signals are used to report the quantity of the fusion proteins in the soluble fraction of the cell lysate. After applying a heat shock, insoluble protein aggregates are removed by centrifugation. Subsequently, the amount of remaining protein in the supernatant is quantified by in-gel fluorescence analysis and compared to samples without a heat shock treatment. Over 60 recombinant membrane proteins from Escherichia coli were subject to this screening in the presence and absence of a few commonly used detergents, and the results were analyzed. Because no sophisticated protein purification is required, this TPF technique is suitable to high throughput expression screening of recombinant membrane proteins as well as soluble ones and can be used to prioritize target proteins based on their thermal stabilities for subsequent large scale expression and structural studies. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. Preparation and thermal performance of paraffin/Nano-SiO2 nanocomposite for passive thermal protection of electronic devices

    International Nuclear Information System (INIS)

    Wang, Yaqin; Gao, Xuenong; Chen, Peng; Huang, Zhaowen; Xu, Tao; Fang, Yutang; Zhang, Zhengguo

    2016-01-01

    Highlights: • Three types of paraffin/nano-SiO 2 nanocomposites were prepared and characterized. • Thermo-physical properties of these composites were determined and compared. • One composite with lower thermal conductivity showed better thermal insulation properties. • This composite was identified as thermal insulation material for electronic components. - Abstract: In this paper, three grades of nano silicon dioxide (nano-SiO 2 ), NS1, NS2 and NS3, were mixed into paraffin to prepare nanocomposites as novel insulation materials for electronic passive thermal protection applications. The optimal mass percentages of paraffin for the three composites, NS1P, NS2P and NS3P, were determined to be 75%, 70% and 65%, respectively. Investigations by means of scanning electron micrographs (SEM), differential scanning calorimeter (DSC), thermogravimetric analysis (TG), hot disk analyzer and thermal protection performance tests were devoted to the morphology, thermal properties and thermal protection performance analysis of composites. Experimental results showed that paraffin uniformly distributed into the pores and on the surface of nano-SiO 2 . Melting points of composites declined and experimental latent heat became lower than the calculated values with the decrease of nano-SiO 2 pore size. The NS1P composite had larger thermal storage capacity, better reliability and stability compared with NS2P and NS3P. In addition, compared with 90% wt.% paraffin/EG composite, the incorporation of NS1 (25 wt.%) into paraffin caused not only 63.2% reduction in thermal conductivity, but also 21.8% increase in thermal protection time affected by the ambient temperature. Thus those good properties confirmed that NS1P (75 wt.%) composite was a viable candidate for protecting electronic devices under high temperature environment.

  16. Radiative shocks with electron thermal conduction

    International Nuclear Information System (INIS)

    Borkowski, Kazimierz.

    1988-01-01

    The authors studies the influence of electron thermal conduction on radiative shock structure for both one- and two-temperature plasmas. The dimensionless ratio of the conductive length to the cooling length determines whether or not conduction is important, and shock jump conditions with conduction are established for a collisionless shock front. He obtains approximate solutions with the assumptions that the ionization state of the gas is constant and the cooling rate is a function of temperature alone. In the absence of magnetic fields, these solutions indicate that conduction noticeably influences normal-abundance interstellar shocks with velocities 50-100 km s -1 and dramatically affects metal-dominated shocks over a wide range of shock velocities. Magnetic fields inhibit conduction, but the conductive energy flux and the corresponding decrease in the post-shock electron temperature may still be appreciable. He calculates detailed steady-state radiative shock models in gas composed entirely of oxygen, with the purpose of explaining observations of fast-moving knots in Cas A and other oxygen-rich supernova remnants (SNRs). The O III ion, whose forbidden emission usually dominates the observed spectra, is present over a wide range of shock velocities, from 100 to 170 kms -1 . All models with conduction have extensive warm photoionization zones, which provides better agreement with observed optical (O I) line strengths. However, the temperatures in these zones could be lowered by (Si II) 34.8 μm and (Ne II) 12.8 μm cooling if Si and Ne are present in appreciable abundance relative to O. Such low temperatures would be inconsistent with the observed (O I) emission in oxygen-rich SNRs

  17. Thermal stability of segmented polyurethane elastomers reinforced by clay particles

    Directory of Open Access Journals (Sweden)

    Pavličević Jelena

    2009-01-01

    Full Text Available The aim of this work was to determine the influence of clay nanoparticles on thermal properties of segmented polyurethanes based on hexamethylene- diisocyanate, aliphatic polycarbonate diol and 1,4-butanediol as chain extender. The organically modified particles of montmorillonite and bentonite were used as reinforcing fillers. The structure of elastomeric materials was varied either by diol type or chain extender content. The ratio of OH groups from diol and chain extender (R was either 1 or 10. Thermal properties of prepared materials were determined using modulated differential scanning calorimetry (MDSC. Thermal stability of obtained elastomers has been studied by simultaneously thermogravimetry coupled with DSC. The glass transition temperature, Tg, of soft segments for all investigated samples was about -33°C. On the basis of DTG results, it was concluded that obtained materials were very stable up to 300°C.

  18. Flexible all-carbon photovoltaics with improved thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Chun; Ishihara, Hidetaka; Sodhi, Jaskiranjeet; Chen, Yen-Chang; Siordia, Andrew; Martini, Ashlie; Tung, Vincent C., E-mail: ctung@ucmerced.edu

    2015-04-15

    The structurally robust nature of nanocarbon allotropes, e.g., semiconducting single-walled carbon nanotubes (SWCNTs) and C{sub 60}s, makes them tantalizing candidates for thermally stable and mechanically flexible photovoltaic applications. However, C{sub 60}s rapidly dissociate away from the basal of SWCNTs under thermal stimuli as a result of weak intermolecular forces that “lock up” the binary assemblies. Here, we explore use of graphene nanoribbons (GNRs) as geometrically tailored protecting layers to suppress the unwanted dissociation of C{sub 60}s. The underlying mechanisms are explained using a combination of molecular dynamics simulations and transition state theory, revealing the temperature dependent disassociation of C{sub 60}s from the SWCNT basal plane. Our strategy provides fundamental guidelines for integrating all-carbon based nano-p/n junctions with optimized structural and thermal stability. External quantum efficiency and output current–voltage characteristics are used to experimentally quantify the effectiveness of GNR membranes under high temperature annealing. Further, the resulting C{sub 60}:SWCNT:GNR ternary composites display excellent mechanical stability, even after iterative bending tests. - Graphical abstract: The incorporation of solvent resistant, mechanically flexible and electrically addressable 2-D soft graphene nanoribbons facilitates the assembly of photoconductive carbon nano-p/n junctions for thermally stable and flexible photovoltaic cells.

  19. Flexible all-carbon photovoltaics with improved thermal stability

    International Nuclear Information System (INIS)

    Tang, Chun; Ishihara, Hidetaka; Sodhi, Jaskiranjeet; Chen, Yen-Chang; Siordia, Andrew; Martini, Ashlie; Tung, Vincent C.

    2015-01-01

    The structurally robust nature of nanocarbon allotropes, e.g., semiconducting single-walled carbon nanotubes (SWCNTs) and C 60 s, makes them tantalizing candidates for thermally stable and mechanically flexible photovoltaic applications. However, C 60 s rapidly dissociate away from the basal of SWCNTs under thermal stimuli as a result of weak intermolecular forces that “lock up” the binary assemblies. Here, we explore use of graphene nanoribbons (GNRs) as geometrically tailored protecting layers to suppress the unwanted dissociation of C 60 s. The underlying mechanisms are explained using a combination of molecular dynamics simulations and transition state theory, revealing the temperature dependent disassociation of C 60 s from the SWCNT basal plane. Our strategy provides fundamental guidelines for integrating all-carbon based nano-p/n junctions with optimized structural and thermal stability. External quantum efficiency and output current–voltage characteristics are used to experimentally quantify the effectiveness of GNR membranes under high temperature annealing. Further, the resulting C 60 :SWCNT:GNR ternary composites display excellent mechanical stability, even after iterative bending tests. - Graphical abstract: The incorporation of solvent resistant, mechanically flexible and electrically addressable 2-D soft graphene nanoribbons facilitates the assembly of photoconductive carbon nano-p/n junctions for thermally stable and flexible photovoltaic cells.

  20. Thermal electron mobilities in low density gaseous mixtures

    International Nuclear Information System (INIS)

    Dmitriev, O.W.; Tchorzewska, W.; Szamrej, I.; Forys, M.

    1992-01-01

    A new method of obtaining thermal electron mobilities from experimental dependencies observed in the electron swarm is described; the method is suitable for both electron accepting and non-accepting systems. The electron mobilities for CO 2 , CH 4 C 2 H 6 as well as for N 2 , Ar, Xe, Kr and their mixtures with carbon dioxide are obtained. (Author)

  1. Electron thermal transport in tokamak plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Konings, J A

    1994-11-30

    The process of fusion of small nuclei thereby releasing energy, as it occurs continuously in the sun, is essential for the existence of mankind. The same process applied in a controlled way on earth would provide a clean and an abundant energy source, and be the long term solution of the energy problem. Nuclear fusion requires an extremely hot (10{sup 8} K) ionized gas, a plasma, that can only be maintained if it is kept insulated from any material wall. In the so called `tokamak` this is achieved by using magnetic fields. The termal insulation, which is essential if one wants to keep the plasma at the high `fusion` temperature, can be predicted using basic plasma therory. A comparison with experiments in tokamaks, however, showed that the electron enery losses are ten to hundred times larger than this theory predicts. This `anomalous transport` of thermal energy implies that, to reach the condition for nuclear fusion, a fusion reactor must have very large dimensions. This may put the economic feasibility of fusion power in jeopardy. Therefore, in a worldwide collaboration, physicists study tokamak plasmas in an attempt to understand and control the energy losses. From a scientific point of view, the mechanisms driving anomalous transport are one of the challenges in fudamental plasma physics. In Nieuwegein, a tokamak experiment (the Rijnhuizen Tokamak Project, RTP) is dedicated to the study of anomalous transport, in an international collaboration with other laboratories. (orig./WL).

  2. Transport of runaway and thermal electrons due to magnetic microturbulence

    International Nuclear Information System (INIS)

    Mynick, H.E.; Strachan, J.D.

    1981-01-01

    The ratio of the runaway electron confinement to thermal electron energy confinement is derived for tokamaks where both processes are determined by free streaming along stochastic magnetic field lines. The runaway electron confinement is enhanced at high runaway electron energies due to phase averaging over the magnetic perturbations when the runaway electron drift surfaces are displaced from the magnetic surfaces. Comparison with experimental data from LT-3, Ormak, PLT, ST, and TM-3 indicates that magnetic stochasticity may explain the relative transport rates of runaways and thermal electron energy

  3. High-power electronics thermal management with intermittent multijet sprays

    International Nuclear Information System (INIS)

    Panão, Miguel R.O.; Correia, André M.; Moreira, António L.N.

    2012-01-01

    Thermal management plays a crucial role in the development of high-power electronics devices, e.g. in electric vehicles. The greatest energy demands occur during power peaks, implying dynamic thermal losses within the vehicle’s driving cycle. Therefore, the need for devising intelligent thermal management systems able to efficiently respond to these power peaks has become a technological challenge. Experiments have been performed with methanol in order to quantify the maximum heat flux removed by a multijet spray to keep the 4 cm 2 surface temperature stabilized and below the threshold of 125 °C. A multijet atomization strategy consists in producing a spray through the multiple and simultaneous impact of N j cylindrical jets. Moreover, the spray intermittency is expressed through the duty cycle (DC), which depends on the frequency and duration of injection. Results evidence that: i) a shorter time between consecutive injection cycles enables a better distribution of the mass flow rate, resulting in larger heat transfer coefficient values, as well as higher cooling efficiencies; ii) compared with continuous sprays, the analysis evidences that an intermittent spray allows benefiting more from phase-change convection. Moreover, the mass flux is mainly affecting heat transfer rather than differences induced in the spray structure by using different multijet configurations. - Highlights: ► Intermittent spray cooling (ISC) is advantageous for intelligent thermal management. ► Distributing the mass flow rate through ISC improves heat transfer. ► Multijet sprays with increasing number of jets have higher heat transfer rates. ► ISC with multijet sprays benefit more from phase-change than continuous sprays.

  4. Explanation of L→H mode transition based on gradient stabilization of edge thermal fluctuations

    International Nuclear Information System (INIS)

    Stacey, W.M.

    1996-01-01

    A linear analysis of thermal fluctuations, using a fluid model which treats the large radial gradient related phenomena in the plasma edge, leads to a constraint on the temperature and density gradients for stabilization of edge temperature fluctuations. A temperature gradient, or conductive edge heat flux, threshold is identified. It is proposed that the L→H transition takes place when the conductive heat flux to the edge produces a sufficiently large edge temperature gradient to stabilize the edge thermal fluctuations. The consequences following from this mechanism for the L→H transition are in accord with observed phenomena associated with the L→H transition and with the observed parameter dependences of the power threshold. First, a constraint is established on the edge temperature and density gradients that are sufficient for the stability of edge temperature fluctuations. A slab approximation for the thin plasma edge and a fluid model connected to account for the large radial gradients present in the plasma edge are used. Equilibrium solutions are characterized by the value of the density and of its gradient L n -1 double-bond - n -1 , etc. Temperature fluctuations expanded about the equilibrium value are then used in the energy balance equation summed over plasma ions, electrons and impurities to obtain, after linearization, an expression for the growth rate ω of edge localized thermal fluctuations. Thermal stability of the equilibrium solution requires ω ≤ 0, which establishes a constraint that must be satisfied by L n -1 and L T -1 . The limiting value of the constraint (ω = 0) leads to an expression for the minimum value of that is sufficient for thermal stability, for a given value of L T -1. It is found that there is a minimum value of the temperature gradient, (L T -1 ) min that is necessary for a stable solution to exist for any value of L n -1

  5. A self-adaptive thermal switch array for rapid temperature stabilization under various thermal power inputs

    International Nuclear Information System (INIS)

    Geng, Xiaobao; Patel, Pragnesh; Narain, Amitabh; Meng, Dennis Desheng

    2011-01-01

    A self-adaptive thermal switch array (TSA) based on actuation by low-melting-point alloy droplets is reported to stabilize the temperature of a heat-generating microelectromechanical system (MEMS) device at a predetermined range (i.e. the optimal working temperature of the device) with neither a control circuit nor electrical power consumption. When the temperature is below this range, the TSA stays off and works as a thermal insulator. Therefore, the MEMS device can quickly heat itself up to its optimal working temperature during startup. Once this temperature is reached, TSA is automatically turned on to increase the thermal conductance, working as an effective thermal spreader. As a result, the MEMS device tends to stay at its optimal working temperature without complex thermal management components and the associated parasitic power loss. A prototype TSA was fabricated and characterized to prove the concept. The stabilization temperatures under various power inputs have been studied both experimentally and theoretically. Under the increment of power input from 3.8 to 5.8 W, the temperature of the device increased only by 2.5 °C due to the stabilization effect of TSA

  6. Electron-hole drop (EHD) stability in deformation potential well

    International Nuclear Information System (INIS)

    Makarov, A.G.; Tikhodeev, S.G.

    1984-01-01

    In heterogeneously-deformed Ge the stability of electron-hole droplets (EHD) being in a potential well is considered. It is shown that the potential well effect is equivalent to the decrease of effective density of phonon EHD charge. It is pointed out that heating EHD (for example, by IR radiation), can increase the phonon droplet charge and affect its stability

  7. Lignin-based carbon fibers: Carbon nanotube decoration and superior thermal stability

    KAUST Repository

    Xu, Xuezhu

    2014-08-23

    Lignin-based carbon fibers (CFs) decorated with carbon nanotubes (CNTs) were synthesized and their structure, thermal stability and wettability were systematically studied. The carbon fiber precursors were produced by electrospinning lignin/polyacrylonitrile solutions. CFs were obtained by pyrolyzing the precursors and CNTs were subsequently grown on the CFs to eventually achieve a CF–CNT hybrid structure. The processes of pyrolysis and CNT growth were conducted in a tube furnace using different conditions and the properties of the resultant products were studied and compared. The CF–CNT hybrid structure produced at 850 °C using a palladium catalyst showed the highest thermal stability, i.e., 98.3% residual weight at 950 °C. A mechanism for such superior thermal stability was postulated based on the results from X-ray diffraction, Raman spectroscopy, scanning and transmission electron microscopy, and electron energy loss spectroscopy analyses. The dense CNT decoration was found to increase the hydrophobicity of the CFs.

  8. Simulation studies on stability of hot electron plasma

    International Nuclear Information System (INIS)

    Ohsawa, Yukiharu

    1985-01-01

    Stability of a hot electron plasma in an NBT(EBT)-like geometry is studied by using a 2-1/2 dimensional relativistic, electromagnetic particle code. For the low-frequency hot electron interchange mode, comparison of the simulation results with the analytical predictions of linear stability theory show fairly good agreement with the magnitude of the growth rates calculated without hot electron finite Larmor radius effects. Strong stabilizing effects by finite Larmor radius of the hot electrons are observed for short wavelength modes. As for the high-frequency hot electron interchange mode, there is a discrepancy between the simulation results and the theory. The high-frequency instability is not observed though a parameter regime is chosen in which the high-frequency hot electron interchange mode is theoretically predicted to grow. Strong cross-field diffusion in a poloidal direction of the hot electrons might explain the stability. Each particle has a magnetic drift velocity, and the speed of the magnetic drift is proportional to the kinetic energy of each particle. Hence, if the particles have high temperature, the spread of the magnetic drift velocity is large. This causes a strong cross-field diffusion of the hot electrons. In the simulation for this interchange mode, an enhanced temperature relaxation is observed between the hot and cold electrons although the theoretically predicted high frequency modes are stable. (Nogami, K.)

  9. Enhanced thermal stability of RuO2/polyimide interface for flexible device applications

    Science.gov (United States)

    Music, Denis; Schmidt, Paul; Chang, Keke

    2017-09-01

    We have studied the thermal stability of RuO2/polyimide (Kapton) interface using experimental and theoretical methods. Based on calorimetric and spectroscopic analyses, this inorganic-organic system does not exhibit any enthalpic peaks as well as all bonds in RuO2 and Kapton are preserved up to 500 °C. In addition, large-scale density functional theory based molecular dynamics, carried out in the same temperature range, validates the electronic structure and points out that numerous Ru-C and a few Ru-O covalent/ionic bonds form across the RuO2/Kapton interface. This indicates strong adhesion, but there is no evidence of Kapton degradation upon thermal excitation. Furthermore, RuO2 does not exhibit any interfacial bonds with N and H in Kapton, providing additional evidence for the thermal stability notion. It is suggested that the RuO2/Kapton interface is stable due to aromatic architecture of Kapton. This enhanced thermal stability renders Kapton an appropriate polymeric substrate for RuO2 containing systems in various applications, especially for flexible microelectronic and energy devices.

  10. On thermal stability of cyanocomplexes of some transition metals

    International Nuclear Information System (INIS)

    Sergeeva, A.N.; Pavlenko, L.I.; Dovgej, V.V.; Zubritskaya, D.I.; Tkachenko, Zh.I.

    1981-01-01

    The experimental data on the study of thermal stability of the coordination cyanides of the composition M'sub(x)[M''(CN)sub(y)]xnHsub(2)O, where M'=K; M''=V(2,3), Mo(2,4), Re(3,5), Ru(2); x=3,4; y=6-8; n=1-3, are generalized and systematized. Three main stages of decomposition of cyanocomlexes, proceeding in argon medium at 20-900 deg, are established. Hexacyanocomplexes of Re(3), Mo(2), Ru(2), V(2) according to their increasing thermal stability can be arranged in the series: K 3 [Re(CN) 6 ] 4 [Mo(CN) 6 ] 4 [Ru(CN) 6 ] 4 [V(CN) 6 ], from which it follows that cyanocomplexes of d-metals of periods 6 and 5 are less thermally stable than similar complexes of d-metal of period 4. The decomposition of cyanides of the type M(CN) 2 in the case of ruthenium ends with the formation of free metal at 470-670 deg, for rhenium - with the formation of free metal and rhenium nitride ReN 2 at 680-700 deg, for molybdenum - molybdenum carbide Mo 2 C at > 670 deg, for vanadium - vanadium carbide VC at 705 deg [ru

  11. Autoxidation of jet fuels: Implications for modeling and thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Heneghan, S.P. [Univ. of Dayton Research Institute, OH (United States); Chin, L.P. [Systems Research Laboratories, Inc., Dayton, OH (United States)

    1995-05-01

    The study and modeling of jet fuel thermal deposition is dependent on an understanding of and ability to model the oxidation chemistry. Global modeling of jet fuel oxidation is complicated by several facts. First, liquid jet fuels are hard to heat rapidly and fuels may begin to oxidize during the heat-up phase. Non-isothermal conditions can be accounted for but the evaluation of temperature versus time is difficult. Second, the jet fuels are a mixture of many compounds that may oxidize at different rates. Third, jet fuel oxidation may be autoaccelerating through the decomposition of the oxidation products. Attempts to model the deposition of jet fuels in two different flowing systems showed the inadequacy of a simple two-parameter global Arrhenius oxidation rate constant. Discarding previous assumptions about the form of the global rate constants results in a four parameter model (which accounts for autoacceleration). This paper discusses the source of the rate constant form and the meaning of each parameter. One of these parameters is associated with the pre-exponential of the autoxidation chain length. This value is expected to vary inversely to thermal stability. We calculate the parameters for two different fuels and discuss the implication to thermal and oxidative stability of the fuels. Finally, we discuss the effect of non-Arrhenius behavior on current modeling of deposition efforts.

  12. Thermal stability of low dose Ga+ ion irradiated spin valves

    International Nuclear Information System (INIS)

    Qi Xianjin; Wang Yingang; Zhou Guanghong; Li Ziquan

    2009-01-01

    The thermal stability of low dose Ga + ion irradiated spin valves has been investigated and compared with that of the as-prepared ones. The dependences of exchange field, measured using vibrating sample magnetometer at room temperature, on magnetic field sweep rate and time spent at negative saturation of the pinned ferromagnetic layer, and training effect were explored. The training effect is observed on both the irradiated spin valves and the as-prepared ones. The magnetic field sweep rate dependence of the exchange bias field of the irradiated spin valves is nearly the same as that of the as-prepared ones. For the as-prepared structure thermal activation has been observed, which showed that holding the irradiated structure at negative saturation of the pinned ferromagnetic layer for up to 28 hours results in no change in the exchange field. The results indicate that the thermal stability of the ion irradiated spin valves is the same as or even better than the as-prepared ones.

  13. In Situ Study of Thermal Stability of Copper Oxide Nanowires at Anaerobic Environment

    Directory of Open Access Journals (Sweden)

    Lihui Zhang

    2014-01-01

    Full Text Available Many metal oxides with promising electrochemical properties were developed recently. Before those metal oxides realize the use as an anode in lithium ion batteries, their thermal stability at anaerobic environment inside batteries should be clearly understood for safety. In this study, copper oxide nanowires were investigated as an example. Several kinds of in situ experiment methods including in situ optical microscopy, in situ Raman spectrum, and in situ transmission electron microscopy were adopted to fully investigate their thermal stability at anaerobic environment. Copper oxide nanowires begin to transform as copper(I oxide at about 250°C and finish at about 400°C. The phase transformation proceeds with a homogeneous nucleation.

  14. Using high thermal stability flexible thin film thermoelectric generator at moderate temperature

    Science.gov (United States)

    Zheng, Zhuang-Hao; Luo, Jing-Ting; Chen, Tian-Bao; Zhang, Xiang-Hua; Liang, Guang-Xing; Fan, Ping

    2018-04-01

    Flexible thin film thermoelectric devices are extensively used in the microscale industry for powering wearable electronics. In this study, comprehensive optimization was conducted in materials and connection design for fabricating a high thermal stability flexible thin film thermoelectric generator. First, the thin films in the generator, including the electrodes, were prepared by magnetron sputtering deposition. The "NiCu-Cu-NiCu" multilayer electrode structure was applied to ensure the thermal stability of the device used at moderate temperature in an air atmosphere. A design with metal layer bonding and series accordant connection was then employed. The maximum efficiency of a single PN thermocouple generator is >11%, and the output power loss of the generator is <10% after integration.

  15. Electronic structure theory of alloy phase stability

    International Nuclear Information System (INIS)

    Turchi, P.E.A.; Sluiter, M.

    1992-01-01

    We present a brief overview of the advanced methodology which has been developed and applied to the study of phase stability properties in substitutional alloys. The approach is based on the real space version of the Generalized Perturbation Method within the Korringa-Kohn-Rostoker multiple scattering formulation of the Coherent Potential Approximation. Temperature effects are taken into account with a generalized meanfield approach, namely the Cluster Variation Method, or with Monte-Carlo simulations. We show that this approach is well suited for studying ground state properties of substitutional alloys, for calculating energies of idealized interfaces and antiphase boundaries, and finally to compute alloy phase diagrams

  16. Coulomb thermal properties and stability of the Io plasma torus

    Science.gov (United States)

    Barbosa, D. D.; Coroniti, F. V.; Eviatar, A.

    1983-01-01

    Coulomb collisional energy exchange rates are computed for a model of the Io plasma torus consisting of newly created pickup ions, a background of thermally degraded intermediary ions, and a population of cooler electrons. The electrons are collisionally heated by both the pickup ions and background ions and are cooled by electron impact excitation of plasma ions which radiate in the EUV. It is found that a relative concentration of S III pickup ions forbidden S III/electrons = 0.1 with a temperature of 340 eV can deliver energy to the electrons at a rate of 3 x 10 to the -13th erg/cu cm per sec, sufficient to power the EUV emissions in the Io torus. The model predicts a background ion temperature Ti of about 53 eV and an electron temperature Te of about 5.5 eV on the basis of steady-state energy balance relations at Coulomb rates. The model also predicts electron temperature fluctuations at the 30 percent level on a time scale of less than 11 hours, consistent with recent observations of this phenomenon.

  17. On the thermal stability of radiation-dominated accretion disks

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Yan-Fei; Stone, James M. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Davis, Shane W. [Canadian Institute for Theoretical Astrophysics, Toronto, ON M5S3H4 (Canada)

    2013-11-20

    We study the long-term thermal stability of radiation-dominated disks in which the vertical structure is determined self-consistently by the balance of heating due to the dissipation of MHD turbulence driven by magneto-rotational instability (MRI) and cooling due to radiation emitted at the photosphere. The calculations adopt the local shearing box approximation and utilize the recently developed radiation transfer module in the Athena MHD code based on a variable Eddington tensor rather than an assumed local closure. After saturation of the MRI, in many cases the disk maintains a steady vertical structure for many thermal times. However, in every case in which the box size in the horizontal directions are at least one pressure scale height, fluctuations associated with MRI turbulence and dynamo action in the disk eventually trigger a thermal runaway that causes the disk to either expand or contract until the calculation must be terminated. During runaway, the dependence of the heating and cooling rates on total pressure satisfy the simplest criterion for classical thermal instability. We identify several physical reasons why the thermal runaway observed in our simulations differ from the standard α disk model; for example, the advection of radiation contributes a non-negligible fraction to the vertical energy flux at the largest radiation pressure, most of the dissipation does not happen in the disk mid-plane, and the change of dissipation scale height with mid-plane pressure is slower than the change of density scale height. We discuss how and why our results differ from those published previously. Such thermal runaway behavior might have important implications for interpreting temporal variability in observed systems, but fully global simulations are required to study the saturated state before detailed predictions can be made.

  18. Ionic liquid thermal stabilities: decomposition mechanisms and analysis tools.

    Science.gov (United States)

    Maton, Cedric; De Vos, Nils; Stevens, Christian V

    2013-07-07

    The increasing amount of papers published on ionic liquids generates an extensive quantity of data. The thermal stability data of divergent ionic liquids are collected in this paper with attention to the experimental set-up. The influence and importance of the latter parameters are broadly addressed. Both ramped temperature and isothermal thermogravimetric analysis are discussed, along with state-of-the-art methods, such as TGA-MS and pyrolysis-GC. The strengths and weaknesses of the different methodologies known to date demonstrate that analysis methods should be in line with the application. The combination of data from advanced analysis methods allows us to obtain in-depth information on the degradation processes. Aided with computational methods, the kinetics and thermodynamics of thermal degradation are revealed piece by piece. The better understanding of the behaviour of ionic liquids at high temperature allows selective and application driven design, as well as mathematical prediction for engineering purposes.

  19. Thermal stability evaluation of palm oil as energy transport media

    International Nuclear Information System (INIS)

    Wan Nik, W.B.; Ani, F.N.; Masjuki, H.H.

    2005-01-01

    The thermal stability of palm oil as energy transport media in a hydraulic system was studied. The oils were aged by circulating the oil in an open loop hydraulic system at an isothermal condition of 55 deg. C for 600 h. The thermal behavior and kinetic parameters of fresh and degraded palm oil, with and without oxidation inhibitor, were studied using the dynamic heating rate mode of a thermogravimetric analyser (TGA). Viscometric properties, total acid number and iodine value analyses were used to complement the TGA data. The thermodynamic parameter of activation energy of the samples was determined by direct Arrhenius plot and integral methods. The results may have important applications in the development of palm oil based hydraulic fluid. The results were compared with commercial vegetable based hydraulic fluid. The use of F10 and L135 additives was found to suppress significantly the increase of acid level and viscosity of the fluid

  20. Testing of Method for Assessing of Room Thermal Stability

    Directory of Open Access Journals (Sweden)

    Charvátová Hana

    2017-01-01

    Full Text Available The paper presents the interim results of our research on the developing methodological procedure which could be used for assessment of a thermal stability of buildings with regards to its thermal accumulative parameters. The principle of testing is based on a combination of computer simulation of cooled room model developed in COMSOL Multiphysics software and on theoretical calculations with respect to compliance with valid European and Czech technical standards used in building industry and architecture under conditions obtained by real measurement for the room to be tested. The presented example shows the effect of the heataccumulation properties of the outside wall insulation materials on the course of the cooling room for winter conditions.

  1. Thermal hydraulic stability in a pressure tube nuclear reactor

    International Nuclear Information System (INIS)

    Villani, A.; Ravetta, R.; Mansani, L.

    1986-01-01

    The CIRENE plant which will undergo preoperational tests in the near future is equipped with a 40 MW(e) Heavy Water moderated Boiling Light Water cooled Reactor (HWBLWR); at the start-up and up to about 30 % of nominal power, the necessary low coolant density is obtained injecting into the core a mixture of liquid and steam. To verify the thermal-hydraulic stability of the plant in this situation, tests have been carried out in a facility simulating two full scale power channels; the system stability has been confirmed in the reference conditions, and is not reduced by even a significant reduction of the liquid flowrate, where a decrease in liquid temperature has some negative effect and steam flowrate has a small influence. (author)

  2. BIOCHAR MODIFICATION, THERMAL STABILITY AND TOXICITY OF PRODUCTS MODIFICATION

    Directory of Open Access Journals (Sweden)

    Romana FRIEDRICHOVÁ

    2017-12-01

    Full Text Available Biochar is a product obtained from processing of waste biomass. The main application of biochar is in soil and environment remediation. Some new applications of this carbonaceous material take advantage of its adsorption capacity use it as a heterogeneous catalyst for energy storage and conversion etc. This contribution describes thermal stability of the original biochar. It discusses biochar modified by chemical and physical methods including a new compound of biochar-graphene oxide. The purpose of the modifications is to increase its active surface to introduce active functional groups into the carbon structure of biochar in relation to fire safety and toxicity of those products.

  3. Thermal effects on the stability of excited atoms in cavities

    International Nuclear Information System (INIS)

    Khanna, F. C.; Malbouisson, A. P. C.; Malbouisson, J. M. C.; Santana, A. E.

    2010-01-01

    An atom, coupled linearly to an environment, is considered in a harmonic approximation in thermal equilibrium inside a cavity. The environment is modeled by an infinite set of harmonic oscillators. We employ the notion of dressed states to investigate the time evolution of the atom initially in the first excited level. In a very large cavity (free space) for a long elapsed time, the atom decays and the value of its occupation number is the physically expected one at a given temperature. For a small cavity the excited atom never completely decays and the stability rate depends on temperature.

  4. Microstructural, thermal and antibacterial properties of electron beam irradiated Bombyx mori silk fibroin films

    Energy Technology Data Exchange (ETDEWEB)

    Asha, S.; Sanjeev, Ganesh, E-mail: ganeshsanjeev@rediffmail.com [Microtron Center, Department of Studies in Physics, Mangalore University, Mangalagangotri - 574199 (India); Sangappa [Department of Studies in Physics, Mangalore University, Mangalagangotri - 574199 (India); Naik, Prashantha; Chandra, K. Sharat [Department of Biosciences, Mangalore University, Mangalagangotri - 574199 (India)

    2014-04-24

    The Bombyx mori silk fibroin (SF) films were prepared by solution casting method and the effects of electron beam on structural, thermal and antibacterial responses of the prepared films were studied. The electron irradiation for different doses was carried out using 8 MeV Microtron facility at Mangalore University. The changes in microstructural parameters and thermal stability of the films were investigated using Wide Angle X-ray Scattering (WAXS) and thermogravimetric analysis (TGA) respectively. Both microstructuralline parameters (crystallite size and lattice strain (g in %)) and thermal stability of the irradiated films have increased with radiation dosage. Agar diffusion method demonstrated the antibacterial activity of SF film which was increased after irradiation on both Gram-positive and Gram-negative species.

  5. Ionoluminscence of partially-stabilized zirconia for thermal barrier coatings

    International Nuclear Information System (INIS)

    Rebollo, N.R.; Ruvalcaba-Sil, J.L.; Miranda, J.

    2007-01-01

    Ionoluminescence is explored as an alternative technique to study the high temperature phase stability of zirconia-based oxides. The evolution of an initially metastable single tetragonal phase towards de-stabilization is investigated for three single-doped zirconia compositions with Y, Yb and Gd. The differences in de-stabilization paths are identified using X-ray diffraction and ionoluminescence; elemental analysis is also performed using particle-induced X-ray emission. X-ray diffraction studies reveal a different scenario for each of the compositions selected; the differences are strongly influenced by the thermodynamic driving forces associated to the fluorite-to-tetragonal displacive transformation. Ionoluminescence studies indicate a significant increment on the signal intensity for de-stabilized samples, relative to previous annealing stages. There are also more subtle differences in the luminescent response from the samples at intermediate annealing stages also related to phase changes. This study provides a basis to characterize phase evolution in single-doped zirconia compositions for thermal insulation applications using luminescence

  6. Thermal stability of DNA quadruplex-duplex hybrids.

    Science.gov (United States)

    Lim, Kah Wai; Khong, Zi Jian; Phan, Anh Tuân

    2014-01-14

    DNA has the capacity to adopt several distinct structural forms, such as duplex and quadruplex helices, which have been implicated in cellular processes and shown to exhibit important functional properties. Quadruplex-duplex hybrids, generated from the juxtaposition of these two structural elements, could find applications in therapeutics and nanotechnology. Here we used NMR and CD spectroscopy to investigate the thermal stability of two classes of quadruplex-duplex hybrids comprising fundamentally distinct modes of duplex and quadruplex connectivity: Construct I involves the coaxial orientation of the duplex and quadruplex helices with continual base stacking across the two components; Construct II involves the orthogonal orientation of the duplex and quadruplex helices with no base stacking between the two components. We have found that for both constructs, the stability of the quadruplex generally increases with the length of the stem-loop incorporated, with respect to quadruplexes comprising nonstructured loops of the same length, which showed a continuous drop in stability with increasing loop length. The stability of these complexes, particularly Construct I, can be substantially influenced by the base-pair steps proximal to the quadruplex-duplex junction. Bulges at the junction are largely detrimental to the adoption of the desired G-quadruplex topology for Construct I but not for Construct II. These findings should facilitate future design and prediction of quadruplex-duplex hybrids.

  7. Thermal expansion coefficient measurement from electron diffraction of amorphous films in a TEM.

    Science.gov (United States)

    Hayashida, Misa; Cui, Kai; Malac, Marek; Egerton, Ray

    2018-05-01

    We measured the linear thermal expansion coefficients of amorphous 5-30 nm thick SiN and 17 nm thick Formvar/Carbon (F/C) films using electron diffraction in a transmission electron microscope. Positive thermal expansion coefficient (TEC) was observed in SiN but negative coefficients in the F/C films. In case of amorphous carbon (aC) films, we could not measure TEC because the diffraction radii required several hours to stabilize at a fixed temperature. Crown Copyright © 2018. Published by Elsevier B.V. All rights reserved.

  8. Thermal Stability of Nanocrystalline Copper for Potential Use in Printed Wiring Board Applications

    Science.gov (United States)

    Woo, Patrick Kai Fai

    Copper is a widely used conductor in the manufacture of printed wiring boards (PWB). The trends in miniaturization of electronic devices create increasing challenges to all electronic industries. In particular PWB manufacturers face great challenges because the increasing demands in greater performance and device miniaturization pose enormous difficulties in manufacturing and product reliability. Nanocrystalline and ultra-fine grain copper can potentially offer increased reliability and functionality of the PWB due to the increases in strength and achievable wiring density by reduction in grain size. The first part of this thesis is concerned with the synthesis and characterization of nanocrystalline and ultra-fine grain-sized copper for potential applications in the PWB industry. Nanocrystalline copper with different amounts of sulfur impurities (25-230ppm) and grain sizes (31-49nm) were produced and their hardness, electrical resistivity and etchability were determined. To study the thermal stability of nanocrystalline copper, differential scanning calorimetry and isothermal heat treatments combined with electron microscopy techniques for microstructural analysis were used. Differential scanning calorimetry was chosen to continuously monitor the grain growth process in the temperature range from 40?C to 400?C. During isothermal annealing experiments samples were annealed at 23?C, 100?C and 300?C to study various potential thermal issues for these materials in PWB applications such as the long-term room temperature thermal stability as well as for temperature excursions above the operation temperature and peak temperature exposure during the PWB manufacturing process. From all annealing experiments the various grain growth events and the overall stability of these materials were analyzed in terms of driving and dragging forces. Experimental evidence is presented which shows that the overall thermal stability, grain boundary character and texture evolution of

  9. Lyapunov stability and thermal stability of partially relaxed fluids and plasmas

    International Nuclear Information System (INIS)

    Elsaesser, K.; Spiess, P.

    1996-01-01

    The relation between the Lyapunov stability of a Hamiltonian system and the thermal stability of a fluid whose temperature is controlled from outside is explored: The free energy as a functional of the correct variables (specific volume, local entropy, and some Clebsch potentials of the velocity) may serve as a Lyapunov functional, depending on the open-quote open-quote Casimirs close-quote close-quote as exchanged quantities. For a multi-species plasma one obtains a sufficient condition for stability: γ(v 2 /c 2 s )-1 s the sound speed. Some features of partially relaxed (T=const) cylindrical plasmas are also discussed. copyright 1996 American Institute of Physics

  10. Preparation of thermal resistant-enhanced separators for lithium ion battery by electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Sohn, Joon Yong; Shin, Junhwa; Nho, Youngchang [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-03-15

    Micro-porous membrane made of polyethylene (PE) or polypropylene (PP) is most widely used as physical separators between the cathode and anode in lithium secondary batteries. However, the polymer membranes so soften or melt when the temperature reaches 130 .deg. C or higher because of thermal shrinkage of the polyolefin separators, and thaw low thermal stability may cause internal short circuiting or lead to thermal runaway. In this study, to realize a highly safe battery, we prepared three type separators as crosslinked PE separator, polymer-coated PE separator, and ceramic-coated PE separators, for lithium secondary battery by electron beam irradiation. We prepared crosslinked PE separators with the improved thermal stability by irradiating a commercial PE separator with an electron beam. A polymer-coated PE separator was prepared by a dip-coating of PVDF-HFP/PEGDMA on both sides of a PE separator followed by an electron beam irradiation. Ceramic-coated PE separator was prepared by coating ceramic particles on a PE separator followed by an electron beam irradiation. The prepared separators were characterized with FT-IR, SEM, electrolyte uptake, ion conductivity, thermal shrinkage and battery performance test.

  11. Thermal and electrochemical stability of tungsten carbide catalyst supports

    Energy Technology Data Exchange (ETDEWEB)

    Chhina, H. [Ballard Power Systems, 9000 Glenlyon Parkway, Burnaby, BC (Canada); Department of Materials Engineering, University of British Columbia, Vancouver, BC (Canada); Campbell, S. [Ballard Power Systems, 9000 Glenlyon Parkway, Burnaby, BC (Canada); Kesler, O. [Department of Mechanical Engineering, University of British Columbia, Vancouver, BC (Canada)

    2007-02-10

    The thermal and electrochemical stability of tungsten carbide (WC), with and without a catalyst dispersed on it, have been investigated to evaluate the potential suitability of the material as an oxidation-resistant catalyst support. Standard techniques currently used to disperse Pt on carbon could not be used to disperse Pt on WC, so an alternative method was developed and used to disperse Pt on both commercially available WC and on carbon for comparison of stability. Electrochemical testing was performed by applying oxidation cycles between +0.6 V and +1.8 V to the support-catalyst material combinations and monitoring the activity of the supported catalyst over 100 oxidation cycles. Comparisons of activity change with cumulative oxidation cycles were made between C and WC supports with comparable loadings of catalyst by weight, solid volume, and powder volume. WC was found to be more thermally and electrochemically stable than currently used carbon support material Vulcan XC-72R. However, further optimization of the particle sizes and dispersion of Pt/WC catalyst/support materials and of comparison standards between new candidate materials and existing carbon-based supports are required. (author)

  12. Thermal Stabilization study of polyacrylonitrile fiber obtained by extrusion

    Directory of Open Access Journals (Sweden)

    Robson Fleming Ribeiro

    2015-12-01

    Full Text Available A low cost and environmental friendly extrusion process of the Polyacrylonitrile (PAN polymer was viabilized by using the 1,2,3-propanetriol (glycerol as a plasticizer. The characterization of the fibers obtained by this process was the object of study in the present work. The PAN fibers were heat treated in the range of 200 °C to 300 °C, which is the temperature range related to the stabilization/oxidation step. This is a limiting phase during the carbon fiber processing. The characterization of the fibers was made using infrared spectroscopy, thermal analysis and microscopy. TGA revealed that the degradation of the extruded PAN co-VA fibers between 250 °C and 350 °C, corresponded to a 9% weight loss to samples analyzed under oxidizing atmosphere and 18% when the samples were analyzed under inert atmosphere. DSC showed that the exothermic reactions on the extruded PAN co-VA fibers under oxidizing synthetic air was broader and the cyclization started at a lower temperature compared under inert atmosphere. Furthermore, FT-IR analysis correlated with thermal anlysis showed that the stabilization/oxidation process of the extruded PAN fiber were coherent with other works that used PAN fibers obtained by other spinning processes.

  13. Preliminary hazards analysis of thermal scrap stabilization system. Revision 1

    International Nuclear Information System (INIS)

    Lewis, W.S.

    1994-01-01

    This preliminary analysis examined the HA-21I glovebox and its supporting systems for potential process hazards. Upon further analysis, the thermal stabilization system has been installed in gloveboxes HC-21A and HC-21C. The use of HC-21C and HC-21A simplified the initial safety analysis. In addition, these gloveboxes were cleaner and required less modification for operation than glovebox HA-21I. While this document refers to glovebox HA-21I for the hazards analysis performed, glovebox HC-21C is sufficiently similar that the following analysis is also valid for HC-21C. This hazards analysis document is being re-released as revision 1 to include the updated flowsheet document (Appendix C) and the updated design basis (Appendix D). The revised Process Flow Schematic has also been included (Appendix E). This Current revision incorporates the recommendations provided from the original hazards analysis as well. The System Design Description (SDD) has also been appended (Appendix H) to document the bases for Safety Classification of thermal stabilization equipment

  14. Pressure effects on the thermal stability of silicon carbide fibers

    Science.gov (United States)

    Jaskowiak, Martha H.; Dicarlo, James A.

    1989-01-01

    Commercially available polymer derived SiC fibers were treated at temperatures from 1000 to 2200 C in vacuum and argon gas pressure of 1 and 1360 atm. Effects of gas pressure on the thermal stability of the fibers were determined through property comparison between the pressure treated fibers and vacuum treated fibers. Investigation of the thermal stability included studies of the fiber microstructure, weight loss, grain growth, and tensile strength. The 1360 atm argon gas treatment was found to shift the onset of fiber weight loss from 1200 to above 1500 C. Grain growth and tensile strength degradation were correlated with weight loss and were thus also inhibited by high pressure treatments. Additional heat treatment in 1 atm argon of the fibers initially treated at 1360 atm argon caused further weight loss and tensile strength degradation, thus indicating that high pressure inert gas conditions would be effective only in delaying fiber strength degradation. However, if the high gas pressure could be maintained throughout composite fabrication, then the composites could be processed at higher temperatures.

  15. Thermal stability and modeling of lithium ion batteries

    Science.gov (United States)

    Botte, Gerardine Gabriela

    2000-10-01

    First-principles mathematical models were developed to examine the effect of the lithium-lithium ion interactions inside the anode particles on the performance of a lithium foil cell. Two different models were developed: the chemical potential model (CPM) that includes the lithium-lithium ion interactions inside the anode particles and the diffusion model (DIM) that does not include the interactions. Significant differences in the thermal and electrochemical performance of the cell were observed between the two approaches. The temperature of the cell predicted by the DFM is higher than the one predicted by the CPM at a given capacity. The discharge time of the cell predicted by the DFM is shorter than the one predicted by the CPM. The results indicate that the cell needs to be modeled using the CPM approach especially at high discharge rates. An evaluation of the numerical techniques, control volume formulation (CVF) and finite difference method (FDM), used for the models was performed. It is shown that the truncation error is the same for both methods when the boundary conditions are of the Dirichlet type, the system of equations are linear and represented in Cartesian coordinates. A new technique to analyze the accuracy of the methods is presented. The only disadvantage of the FDM is that it failed to conserve mass for a small number of nodes when both boundary conditions include a derivative term whereas the CVF did conserve mass for these cases. However, for a large number of nodes the FDM provides mass conservation. It is important to note that the CVF has only (DeltaX) order of accuracy for a Neumann type boundary condition whereas the FDM has (DeltaX) 2 order. The second topic of this dissertation presents a study of the thermal stability of LiPF6 EC:EMC electrolyte for lithium ion batteries. A differential scanning calorimeter (DSC) was used to perform the study of the electrolyte. For first time, the effect of different variables on its thermal stability

  16. Physicochemical properties and thermal stability of quercetin hydrates in the solid state

    Energy Technology Data Exchange (ETDEWEB)

    Borghetti, G.S., E-mail: greicefarm@yahoo.com.br [Programa de Pos-Graduacao em Ciencias Farmaceuticas, Faculdade de Farmacia, Universidade Federal do Rio Grande do Sul, Av. Ipiranga 2752, CEP 90.610-000, Porto Alegre, RS (Brazil); Carini, J.P. [Programa de Pos-Graduacao em Ciencias Farmaceuticas, Faculdade de Farmacia, Universidade Federal do Rio Grande do Sul, Av. Ipiranga 2752, CEP 90.610-000, Porto Alegre, RS (Brazil); Honorato, S.B.; Ayala, A.P. [Departamento de Fisica, Universidade Federal do Ceara, Caixa Postal 6030, CEP 60.455-970, Fortaleza, CE (Brazil); Moreira, J.C.F. [Departamento de Bioquimica, Instituto de Ciencias Basicas da Saude, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos 2600, CEP 90035-003, Porto Alegre, RS (Brazil); Bassani, V.L. [Programa de Pos-Graduacao em Ciencias Farmaceuticas, Faculdade de Farmacia, Universidade Federal do Rio Grande do Sul, Av. Ipiranga 2752, CEP 90.610-000, Porto Alegre, RS (Brazil)

    2012-07-10

    Highlights: Black-Right-Pointing-Pointer Quercetin raw materials may present different degree of hydration. Black-Right-Pointing-Pointer Thermal stability of quercetin in the solid state depends on its degree of hydration. Black-Right-Pointing-Pointer Quercetin dehydrate is thermodynamically more stable than the other crystal forms. - Abstract: In the present work three samples of quercetin raw materials (QCTa, QCTb and QCTc), purchased from different Brazilian suppliers, were characterized employing scanning electron microscopy, Raman spectroscopy, simultaneous thermogravimetry and infrared spectroscopy, differential scanning calorimetry, and variable temperature-powder X-ray diffraction, in order to know their physicochemical properties, specially the thermal stability in solid state. The results demonstrated that the raw materials of quercetin analyzed present distinct crystalline structures, ascribed to the different degree of hydration of their crystal lattice. The thermal stability of these quercetin raw materials in the solid state was highly dependent on their degree of hydration, where QCTa (quercetin dihydrate) was thermodynamically more stable than the other two samples.

  17. Phase stability and electronic structure of transition-metal aluminides

    International Nuclear Information System (INIS)

    Carlsson, A.E.

    1992-01-01

    This paper will describe the interplay between die electronic structure and structural energetics in simple, complex, and quasicrystalline Al-transition metal (T) intermetallics. The first example is the Ll 2 -DO 22 competition in Al 3 T compounds. Ab-initio electronic total-energy calculations reveal surprisingly large structural-energy differences, and show that the phase stability of both stoichiometric and ternary-substituted compounds correlates closely with a quasigap in the electronic density of states (DOS). Secondly, ab-initio calculations for the structural stability of the icosahedrally based Al 12 W structure reveal similar quasigap effects, and provide a simple physical explanation for the stability of the complex aluminide structures. Finally, parametrized tight-binding model calculations for the Al-Mn quasicrystal reveal a large spread in the local Mn DOS behavior, and support a two-site model for the quasicrystal's magnetic behavior

  18. Polyacrolein/mesoporous silica nanocomposite: Synthesis, thermal stability and covalent lipase immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Motevalizadeh, Seyed Farshad; Khoobi, Mehdi; Shabanian, Meisam [Department of Medicinal Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences Research Center, Tehran University of Medical Sciences, Tehran 14176 (Iran, Islamic Republic of); Asadgol, Zahra; Faramarzi, Mohammad Ali [Department of Pharmaceutical Biotechnology, Faculty of Pharmacy and Biotechnology Research Center, Tehran University of Medical Sciences, P.O. Box 14155-6451, Tehran 14176 (Iran, Islamic Republic of); Shafiee, Abbas, E-mail: ashafiee@ams.ac.ir [Department of Medicinal Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences Research Center, Tehran University of Medical Sciences, Tehran 14176 (Iran, Islamic Republic of); Center of Excellence in Biothermodynamics, University of Tehran, Tehran (Iran, Islamic Republic of)

    2013-12-16

    In this work, new polyacrolein/MCM-41 nanocomposites with good phase mixing behavior were prepared through an emulsion polymerization technique. Mesoporous silica was synthesized by in situ assembly of tetraethyl orthosilicate (TEOS) and cetyl trimethyl ammonium bromide (CTAB). The structure and properties of polyacrolein containing nanosized MCM-41 particle (5 and 10 wt%), were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, Dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N{sub 2} adsorption techniques, and thermogravimetric (TGA) analyses. The SEM images from the final powder have revealed good dispersion of the MCM-41 nanoparticles throughout polymeric matrix with no distinct voids between two phases. The results indicated that the thermal properties of the nanocomposite were enhanced by addition of MCM-41. Thermomyces lanuginosa lipase (TLL) was used as a model biocatalyst and successfully immobilized with polyacrolein and the nanocomposite via covalent bonds with the aldehyde groups. The activity between free enzyme, polyacrolein, and MCM-41 nanocomposite (10 wt%)-immobilized TLL was compared. The immobilized lipase with the nanocomposite shows better operational stability such as pH tolerance, thermal and storage stability. In addition, the immobilized lipase with the nanocomposite can be easily recovered and retained at 74% of its initial activity after 15 time reuses. - Graphical abstract: The influence of incorporation of mesoporous MCM-41 nanoparticle with polyacrolein on the thermal properties and enzyme immobilization was investigated. - Highlights: • Polyacrolein/MCM-41 nanocomposites were prepared by emulsion polymerization method. • Thermal stability and char residues in nanocomposites were improved. • Nanocomposites significant effects on immobilization of lipase.

  19. Electrostatic stability of electron-positron plasmas in dipole geometry

    OpenAIRE

    Mishchenko, Alexey; Plunk, Gabriel; Helander, Per

    2017-01-01

    The electrostatic stability of electron-positron plasmas is investigated in the point-dipole and Z-pinch limits of dipole geometry. The kinetic dispersion relation for sub-bounce-frequency instabilities is derived and solved. For the zero-Debye-length case, the stability diagram is found to exhibit singular behavior. However, when the Debye length is non-zero, a fluid mode appears, which resolves the observed singularity, and also demonstrates that both the temperature and density gradients c...

  20. Microstructure and thermal stability of nickel layers electrodeposited from an additive-free sulphamate-based electrolyte

    DEFF Research Database (Denmark)

    Rasmussen, Anette Alsted; Møller, Per; Somers, Marcel A. J.

    2006-01-01

    and scanning electron microscopy and X-ray diffraction; the Vickers hardness was measured in cross sections. The present is meant as a reference for forthcoming articles on the investigation of various strengthening mechanisms on the microstructure, hardness and thermal stability of Ni (alloys) electrodeposits.......The influences of the current density and the temperature on the microstructure and hardness of Ni layers electrodeposited from an additive-free sulphamate bath were investigated. The microstructure and thermal stability of the electrodeposits was investigated with a combination of transmission...

  1. Study on the thermal-hydraulic stability of high burn up STEP III fuel in Japan

    International Nuclear Information System (INIS)

    Ishikawa, M.; Kitamura, H.; Toba, A.; Omoto, A.

    2004-01-01

    Japanese BWR utilities have performed a joint study of the Thermal Hydraulic Stability of High Burn up STEP III Fuel. In this study, the parametric dependency of thermal hydraulic stability threshold was obtained. It was confirmed through experiments that the STEP III Fuel has sufficient stability characteristics. (author)

  2. Verification of the thermal design of electronic equipment

    Energy Technology Data Exchange (ETDEWEB)

    Hienonen, R.; Karjalainen, M.; Lankinen, R. [VTT Automation, Espoo (Finland). ProTechno

    1997-12-31

    The project `Verification of the thermal design of electronic equipment` studied the methodology to be followed in the verification of thermal design of electronic equipment. This project forms part of the `Cool Electronics` research programme funded by TEKES, the Finnish Technology Development Centre. This project was carried out jointly by VTT Automation, Lappeenranta University of Technology, Nokia Research Center and ABB Industry Oy VSD-Technology. The thermal design of electronic equipment has a significant impact on the cost, reliability, tolerance to different environments, selection of components and materials, and ergonomics of the product. This report describes the method for verification of thermal design. It assesses the goals set for thermal design, environmental requirements, technical implementation of the design, thermal simulation and modelling, and design qualification testing and the measurements needed. The verification method covers all packaging levels of electronic equipment from the system level to the electronic component level. The method described in this report can be used as part of the quality system of a corporation. The report includes information about the measurement and test methods needed in the verification process. Some measurement methods for the temperature, flow and pressure of air are described. (orig.) Published in Finnish VTT Julkaisuja 824. 22 refs.

  3. Thermal-Stability and Reconstitution Ability of Listeria Phages P100 and A511

    Directory of Open Access Journals (Sweden)

    Hanie Ahmadi

    2017-12-01

    Full Text Available The study evaluated the thermal-stability of Listeria phages P100 and A511 at temperatures simulating the preparation of ready-to-eat meats. The phage infectivity after heating to 71°C and holding for a minimum of 30 s, before eventually cooling to 4°C were examined. Higher temperatures of 75, 80, and 85°C were also tested to evaluate their effect on phages thermal-stability. This study found that despite minor differences in the amino acid sequences of their structural proteins, the two phages responded differently to high temperatures. P100 activity declined at least 10 log (PFU mL-1 with exposure to 71°C (30 s and falling below the limit of detection (1 log PFU mL-1 while, A511 dropped from 108 to 105 PFU mL-1. Cooling resulted in partial reconstitution of P100 phage particles to 103 PFU mL-1. Exposure to 75°C (30 s abolished A511 activity (8 log PFU mL-1 and both phages showed reconstitution during cooling phase after exposure to 75°C. P100 exhibited reconstitution after treatment at 80°C (30 s, conversely A511 showed no reconstitution activity. Heating P100 to 85°C abolished the reconstitution potential. Substantial differences were found in thermal-stability and reconstitution of the examined phages showing A511 to be more thermo-stable than P100, while P100 exhibited reconstitution during cooling after treatment at 80°C which was absent in A511. The differences in predicted melting temperatures of structural proteins of P100 and A511 were consistent with the observed differences in thermal stability and morphological changes observed with transmission electron microscopy.

  4. Passive thermal management system for downhole electronics in harsh thermal environments

    International Nuclear Information System (INIS)

    Shang, Bofeng; Ma, Yupu; Hu, Run; Yuan, Chao; Hu, Jinyan; Luo, Xiaobing

    2017-01-01

    Highlights: • A passive thermal management system is proposed for downhole electronics. • Electronics temperature can be maintained within 125 °C for six-hour operating time. • The result shows potential application for the logging tool in oil and gas industry. - Abstract: The performance and reliability of downhole electronics will degrade in high temperature environments. Various active cooling techniques have been proposed for thermal management of such systems. However, these techniques require additional power input, cooling liquids and other moving components which complicate the system. This study presents a passive Thermal Management System (TMS) for downhole electronics. The TMS includes a vacuum flask, Phase Change Material (PCM) and heat pipes. The thermal characteristics of the TMS is evaluated experimentally. The results show that the system maintains equipment temperatures below 125 °C for a six-hour operating period in a 200 °C downhole environment, which will effectively protect the downhole electronics.

  5. Cooled electronic system with thermal spreaders coupling electronics cards to cold rails

    Science.gov (United States)

    Chainer, Timothy J; Gaynes, Michael A; Graybill, David P; Iyengar, Madhusudan K; Kamath, Vinod; Kochuparambil, Bejoy J; Schmidt, Roger R; Schultz, Mark D; Simco, Daniel P; Steinke, Mark E

    2013-07-23

    Liquid-cooled electronic systems are provided which include an electronic assembly having an electronics card and a socket with a latch at one end. The latch facilitates securing of the card within the socket or removal of the card from the socket. A liquid-cooled cold rail is disposed at the one end of the socket, and a thermal spreader couples the electronics card to the cold rail. The thermal spreader includes first and second thermal transfer plates coupled to first and second surfaces on opposite sides of the card, and thermally conductive extensions extending from end edges of the plates, which couple the respective transfer plates to the liquid-cooled cold rail. The thermally conductive extensions are disposed to the sides of the latch, and the card is securable within or removable from the socket using the latch without removing the cold rail or the thermal spreader.

  6. Stability enhancement and electronic tunability of two-dimensional SbIV compounds via surface functionalization

    Science.gov (United States)

    Zhou, Wenhan; Guo, Shiying; Liu, Xuhai; Cai, Bo; Song, Xiufeng; Zhu, Zhen; Zhang, Shengli

    2018-01-01

    We propose a family of hydrogenated- and halogenated-SbIV (SbIVX-2) materials that simultaneously have two-dimensional (2D) structures, high stability and appealing electronic properties. Based on first-principles total-energy and vibrational-spectra calculations, SbIVX-2 monolayers are found both thermally and dynamically stable. Varying IV and X elements can rationally tune the electronic properties of SbIVX-2 monolayers, effectively modulating the band gap from 0 to 3.42 eV. Regarding such superior stability and broad band-gap range, SbIVX-2 monolayers are expected to be synthesized in experiments and taken as promising candidates for low-dimensional electronic and optoelectronic devices, such as blue-to-ultraviolet light-emitting diodes (LED) and photodetectors.

  7. Thermal stability and thermal conductivity of phosphorene in phosphorene/graphene van der Waals heterostructures.

    Science.gov (United States)

    Pei, Qing-Xiang; Zhang, Xiaoliang; Ding, Zhiwei; Zhang, Ying-Yan; Zhang, Yong-Wei

    2017-07-14

    Phosphorene, a new two-dimensional (2D) semiconducting material, has attracted tremendous attention recently. However, its structural instability under ambient conditions poses a great challenge to its practical applications. A possible solution for this problem is to encapsulate phosphorene with more stable 2D materials, such as graphene, forming van der Waals heterostructures. In this study, using molecular dynamics simulations, we show that the thermal stability of phosphorene in phosphorene/graphene heterostructures can be enhanced significantly. By sandwiching phosphorene between two graphene sheets, its thermally stable temperature is increased by 150 K. We further study the thermal transport properties of phosphorene and find surprisingly that the in-plane thermal conductivity of phosphorene in phosphorene/graphene heterostructures is much higher than that of the free-standing one, with a net increase of 20-60%. This surprising increase in thermal conductivity arises from the increase in phonon group velocity and the extremely strong phonon coupling between phosphorene and the graphene substrate. Our findings have an important meaning for the practical applications of phosphorene in nanodevices.

  8. Ultrafast Non-Thermal Electron Dynamics in Single Layer Graphene

    Directory of Open Access Journals (Sweden)

    Novoselov K.S.

    2013-03-01

    Full Text Available We study the ultrafast dynamics of non-thermal electron relaxation in graphene upon impulsive excitation. The 10-fs resolution two color pump-probe allows us to unveil the non-equilibrium electron gas decay at early times.

  9. Thermal effects of runaway electrons in an armoured divertor

    International Nuclear Information System (INIS)

    Stad, R.C.L. van der.

    1993-12-01

    This report describes the results of a numerical thermal analysis of the heat deposition of runaway electrons accompanying plasma disruptions in a armoured divertor. The divertor concepts studied are carbon on molybdenum and beryllium on copper. The conclusion is that the runaway electrons can cause melting of the armour as well as melting of the structure and can damage the divertor severely. (orig.)

  10. Power Electronics Thermal Management Research: Annual Progress Report

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, Gilberto [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-10-19

    The objective for this project is to develop thermal management strategies to enable efficient and high-temperature wide-bandgap (WBG)-based power electronic systems (e.g., emerging inverter and DC-DC converter). Reliable WBG devices are capable of operating at elevated temperatures (≥ 175 °Celsius). However, packaging WBG devices within an automotive inverter and operating them at higher junction temperatures will expose other system components (e.g., capacitors and electrical boards) to temperatures that may exceed their safe operating limits. This creates challenges for thermal management and reliability. In this project, system-level thermal analyses are conducted to determine the effect of elevated device temperatures on inverter components. Thermal modeling work is then conducted to evaluate various thermal management strategies that will enable the use of highly efficient WBG devices with automotive power electronic systems.

  11. Ionic conductivity and thermal stability of magnetron-sputtered nanocrystalline yttria-stabilized zirconia

    DEFF Research Database (Denmark)

    Sillassen, M.; Eklund, P.; Sridharan, M.

    2009-01-01

    Thermally stable, stoichiometric, cubic yttria-stabilized zirconia (YSZ) thin-film electrolytes have been synthesized by reactive pulsed dc magnetron sputtering from a Zr–Y (80/20 at. %) alloy target. Films deposited at floating potential had a texture. Single-line profile analysis of the 111 x.......5% at bias voltages of −175 and −200 V with additional incorporation of argon. The films were thermally stable; very limited grain coarsening was observed up to an annealing temperature of 800 °C. Temperature-dependent impedance spectroscopy analysis of the YSZ films with Ag electrodes showed that the in......-plane ionic conductivity was within one order of magnitude higher in films deposited with substrate bias corresponding to a decrease in grain size compared to films deposited at floating potential. This suggests that there is a significant contribution to the ionic conductivity from grain boundaries...

  12. Thermal Stability-Enhanced and High-Efficiency Planar Perovskite Solar Cells with Interface Passivation.

    Science.gov (United States)

    Zhang, Weihai; Xiong, Juan; Jiang, Li; Wang, Jianying; Mei, Tao; Wang, Xianbao; Gu, Haoshuang; Daoud, Walid A; Li, Jinhua

    2017-11-08

    As the electron transport layer (ETL) of perovskite solar cells, oxide semiconductor zinc oxide (ZnO) has been attracting great attention due to its relatively high mobility, optical transparency, low-temperature fabrication, and good environment stability. However, the nature of ZnO will react with the patron on methylamine, which would deteriorate the performance of cells. Although many methods, including high-temperature annealing, doping, and surface modification, have been studied to improve the efficiency and stability of perovskite solar cells with ZnO ETL, devices remain relatively low in efficiency and stability. Herein, we adopted a novel multistep annealing method to deposit a porous PbI 2 film and improved the quality and uniformity of perovskite films. The cells with ZnO ETL were fabricated at the temperature of perovskite film. Interestingly, the PCE of PCBM-passivated cells could reach nearly 19.1%. To our best knowledge, this is the highest PCE value of ZnO-based perovskite solar cells until now. More importantly, PCBM modification could effectively suppress the decomposition of MAPbI 3 and improve the thermal stability of cells. Therefore, the ZnO is a promising candidate of electron transport material for perovskite solar cells in future applications.

  13. Thermal cycling behaviour and thermal stability of uranium-molybdenum alloys of low molybdenum content

    International Nuclear Information System (INIS)

    Decours, J.; Fabrique, B.; Peault, O.

    1963-01-01

    We have studied the behaviour during thermal cycling of as-cast U-Mo alloys whose molybdenum content varies from 0.5 to 3 per cent; results are given concerning grain stability during extended heat treatments and the effect of treatments combining protracted heating with thermal cycling. The thermal cycling treatments were carried out at 550, 575, 600 and 625 deg C for 1000 cycles; the protracted heating experiments were done at 550, 575, 600 and 625 deg C for 2000 hours (4000 hrs at 625 deg C). The 0.5 per cent alloy resists much better to the thermal cycling than does the non-alloyed uranium. This resistance is, however, much lower than that of alloys containing over l per cent, even at 550 deg C it improves after a heat treatment for grain-refining. Alloys of over 1.1 per cent have a very good resistance to a cycling treatment even at 625 deg C, and this behaviour improves with increasing concentrations up to 3 per cent. An increase in the temperature up to the γ-phase has few disadvantages provided that it is followed by rapid cooling (50 to 100 deg C/min). The α grain is fine, the γ-phase is of the modular form, and the behaviour during a thermal cycling treatment is satisfactory. If this cooling is slow (15 deg /hr) the α-grain is coarse and cycling treatment behaviour is identical to that of the 0.5 per cent alloy. The protracted heat treatments showed that the α-grain exhibits satisfactory stability after 2000 hours at 575, 600 and 625 deg C, and after 4000 hours at 625 deg C. A heat cycling treatment carried out after these tests affects only very little the behaviour of these alloys during cycling. (authors) [fr

  14. Application of Thermal Network Model to Transient Thermal Analysis of Power Electronic Package Substrate

    Directory of Open Access Journals (Sweden)

    Masaru Ishizuka

    2011-01-01

    Full Text Available In recent years, there is a growing demand to have smaller and lighter electronic circuits which have greater complexity, multifunctionality, and reliability. High-density multichip packaging technology has been used in order to meet these requirements. The higher the density scale is, the larger the power dissipation per unit area becomes. Therefore, in the designing process, it has become very important to carry out the thermal analysis. However, the heat transport model in multichip modules is very complex, and its treatment is tedious and time consuming. This paper describes an application of the thermal network method to the transient thermal analysis of multichip modules and proposes a simple model for the thermal analysis of multichip modules as a preliminary thermal design tool. On the basis of the result of transient thermal analysis, the validity of the thermal network method and the simple thermal analysis model is confirmed.

  15. Stability of amorphous Ge-As(Sb)-Se films to high-energy electron irradiation

    International Nuclear Information System (INIS)

    Savchenko, N.D.

    1999-01-01

    The results of the investigation of high-energy electron (6.5 MeV) irradiation effect on structure, optical, electrical and mechanical properties for thin films obtained by thermal evaporation of Ge-As-Se and Ge-Sb-Se glasses have been presented. The electron-induced changes in film properties versus average coordination number and relative free volume for bulk glasses have been discussed. It has been found that the higher radiation stability is characteristic to the films deposited from the glasses with the lower relative free volume

  16. Novel polypyrrole films with excellent crystallinity and good thermal stability

    International Nuclear Information System (INIS)

    Jeeju, Pullarkat P.; Varma, Sreekanth J.; Francis Xavier, Puthampadath A.; Sajimol, Augustine M.; Jayalekshmi, Sankaran

    2012-01-01

    Polypyrrole has drawn a lot of interest due to its high thermal and environmental stability in addition to high electrical conductivity. The present work highlights the enhanced crystallinity of polypyrrole films prepared from the redoped sample solution. Initially hydrochloric acid doped polypyrrole was prepared by chemical oxidative polymerization of pyrrole using ammonium peroxidisulphate as oxidant. The doped polypyrrole was dedoped using ammonia solution and then redoped with camphor sulphonic acid. Films were coated on ultrasonically cleaned glass substrates from the redoped sample solution in meta-cresol. The enhanced crystallinity of the polypyrrole films has been established from X-ray diffraction (XRD) studies. The room temperature electrical conductivity of the redoped polypyrrole film is about 30 times higher than that of the hydrochloric acid doped pellet sample. The results of Raman spectroscopy, Differential scanning calorimetry (DSC) and Thermogravimetric analysis (TGA) of the samples support the enhancement in crystallinity. Percentage crystallinity of the samples is estimated from XRD and DSC data. The present work is significant, since crystallinity of films is an important parameter for selecting polymers for specific applications. - Highlights: ► Polypyrrole films redoped with CSA have been prepared from meta-cresol solution. ► The solution casted films exhibit semi-crystallinity and good thermal stability. ► Percentage crystallinity estimated using XRD and DSC analysis is about 65%. ► Raman studies support the enhancement in crystallinity based on XRD and DSC data. ► The conductivity of the film is 30 times higher than that of HCl doped sample.

  17. Novel polypyrrole films with excellent crystallinity and good thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Jeeju, Pullarkat P., E-mail: jeejupp@gmail.com [Division for Research in Advanced Materials, Department of Physics, Cochin University of Science and Technology, Cochin-22, Kerala (India); Varma, Sreekanth J.; Francis Xavier, Puthampadath A.; Sajimol, Augustine M. [Division for Research in Advanced Materials, Department of Physics, Cochin University of Science and Technology, Cochin-22, Kerala (India); Jayalekshmi, Sankaran, E-mail: jayalekshmi@cusat.ac.in [Division for Research in Advanced Materials, Department of Physics, Cochin University of Science and Technology, Cochin-22, Kerala (India)

    2012-06-15

    Polypyrrole has drawn a lot of interest due to its high thermal and environmental stability in addition to high electrical conductivity. The present work highlights the enhanced crystallinity of polypyrrole films prepared from the redoped sample solution. Initially hydrochloric acid doped polypyrrole was prepared by chemical oxidative polymerization of pyrrole using ammonium peroxidisulphate as oxidant. The doped polypyrrole was dedoped using ammonia solution and then redoped with camphor sulphonic acid. Films were coated on ultrasonically cleaned glass substrates from the redoped sample solution in meta-cresol. The enhanced crystallinity of the polypyrrole films has been established from X-ray diffraction (XRD) studies. The room temperature electrical conductivity of the redoped polypyrrole film is about 30 times higher than that of the hydrochloric acid doped pellet sample. The results of Raman spectroscopy, Differential scanning calorimetry (DSC) and Thermogravimetric analysis (TGA) of the samples support the enhancement in crystallinity. Percentage crystallinity of the samples is estimated from XRD and DSC data. The present work is significant, since crystallinity of films is an important parameter for selecting polymers for specific applications. - Highlights: Black-Right-Pointing-Pointer Polypyrrole films redoped with CSA have been prepared from meta-cresol solution. Black-Right-Pointing-Pointer The solution casted films exhibit semi-crystallinity and good thermal stability. Black-Right-Pointing-Pointer Percentage crystallinity estimated using XRD and DSC analysis is about 65%. Black-Right-Pointing-Pointer Raman studies support the enhancement in crystallinity based on XRD and DSC data. Black-Right-Pointing-Pointer The conductivity of the film is 30 times higher than that of HCl doped sample.

  18. Stability of the discretization of the electron avalanche phenomenon

    Energy Technology Data Exchange (ETDEWEB)

    Villa, Andrea, E-mail: andrea.villa@rse-web.it [Ricerca Sul Sistema Energetico (RSE), Via Rubattino 50, 20134, Milano (Italy); Barbieri, Luca, E-mail: luca.barbieri@rse-web.it [Ricerca Sul Sistema Energetico (RSE), Via Rubattino 50, 20134, Milano (Italy); Gondola, Marco, E-mail: marco.gondola@rse-web.it [Ricerca Sul Sistema Energetico (RSE), Via Rubattino 50, 20134, Milano (Italy); Leon-Garzon, Andres R., E-mail: andresricardo.leon@polimi.it [CMIC Department “Giulio Natta”, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano (Italy); Malgesini, Roberto, E-mail: roberto.malgesini@rse-web.it [Ricerca Sul Sistema Energetico (RSE), Via Rubattino 50, 20134, Milano (Italy)

    2015-09-01

    The numerical simulation of the discharge inception is an active field of applied physics with many industrial applications. In this work we focus on the drift-reaction equation that describes the electron avalanche. This phenomenon is one of the basic building blocks of the streamer model. The main difficulty of the electron avalanche equation lies in the fact that the reaction term is positive when a high electric field is applied. It leads to exponentially growing solutions and this has a major impact on the behavior of numerical schemes. We analyze the stability of a reference finite volume scheme applied to this latter problem. The stability of the method may impose a strict mesh spacing, therefore a proper stabilized scheme, which is stable whatever spacing is used, has been developed. The convergence of the scheme is treated as well as some numerical experiments.

  19. Thermal Stability and Material Balance of Nanomaterials in Waste Incineration

    Science.gov (United States)

    Paur, H.-R.; Baumann, W.; Hauser, M.; Lang, I.; Teuscher, N.; Seifert, H.; Stapf, D.

    2017-06-01

    Nanostructured materials are widely used to improve the properties of consumer products such as tires, cosmetics, light weight equipment etc. Due to their complex composition these products are hardly recycled and thermal treatment is preferred. In this study we investigated the thermal stability and material balance of nanostructured metal oxides in flames and in an industrial waste incinerator. We studied the size distribution of nanostructured metal oxides (CeO2, TiO2, SiO2) in a flame reactor and in a heated reaction tube. In the premixed ethylene/air flame, nano-structured CeO2 partly evaporates forming a new particle mode. This is probably due to chemical reactions in the flame. In addition sintering of agglomerates takes place in the flame. In the electrically heated reaction tube however only sintering of the agglomerated nanomaterials is observed. Ceria has a low background in waste incinerators and is therefore a suitable tracer for investigating the fate of nanostructured materials. Low concentrations of Ceria were introduced by a two-phase nozzle into the post-combustion zone of a waste incinerator. By the incineration of coal dust in a burning chamber the Ceria nanoparticles are mainly found in the size range of the fly ash (1 - 10 µm) because of agglomeration. With gas as a fuel less agglomeration was observed and the Ceria nanoparticles were in the particle size range below 1 µm.

  20. Thermal Stability and Material Balance of Nanomaterials in Waste Incineration

    International Nuclear Information System (INIS)

    Paur, H.-R.; Baumann, W.; Hauser, M.; Lang, I.; Teuscher, N.; Seifert, H.; Stapf, D.

    2017-01-01

    Nanostructured materials are widely used to improve the properties of consumer products such as tires, cosmetics, light weight equipment etc. Due to their complex composition these products are hardly recycled and thermal treatment is preferred. In this study we investigated the thermal stability and material balance of nanostructured metal oxides in flames and in an industrial waste incinerator. We studied the size distribution of nanostructured metal oxides (CeO 2 , TiO 2 , SiO 2 ) in a flame reactor and in a heated reaction tube. In the premixed ethylene/air flame, nano-structured CeO 2 partly evaporates forming a new particle mode. This is probably due to chemical reactions in the flame. In addition sintering of agglomerates takes place in the flame. In the electrically heated reaction tube however only sintering of the agglomerated nanomaterials is observed. Ceria has a low background in waste incinerators and is therefore a suitable tracer for investigating the fate of nanostructured materials. Low concentrations of Ceria were introduced by a two-phase nozzle into the post-combustion zone of a waste incinerator. By the incineration of coal dust in a burning chamber the Ceria nanoparticles are mainly found in the size range of the fly ash (1 – 10 µm) because of agglomeration. With gas as a fuel less agglomeration was observed and the Ceria nanoparticles were in the particle size range below 1 µm. (paper)

  1. Thermal stability of nafion membranes under mechanical stress

    Energy Technology Data Exchange (ETDEWEB)

    Quintilii, M; Struis, R [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    The feasibility of adequately modified fluoro-ionomer membranes (NAFION{sup R}) is demonstrated for the selective separation of methanol synthesis products from the raw reactor gas at temperatures around 200{sup o}C. For an economically relevant application of this concept on a technical scale the Nafion membranes should be thin ({approx_equal}10 {mu}m) and thermally stable over a long period of time (1-2 years). In cooperation with industry (Methanol Casale SA, Lugano (CH)), we test the thermal stability of Nafion hollow fibers and supported Nafion thin sheet membranes at temperatures between 160 and 200{sup o}C under mechanical stress by applying a gas pressure difference over the membrane surface ({Delta}P{<=} 40 bar). Tests with the hollow fibers revealed that Nafion has visco-elastic properties. Tests with 50 {mu}m thin Nafion sheets supported by a porous metal carrier at 200{sup o}C and {Delta}P=39 bar showed no mechanical defects over a period of 92 days. (author) 5 figs., 4 refs.

  2. Thermal stability of thiol and silane monolayers: A comparative study

    International Nuclear Information System (INIS)

    Chandekar, Amol; Sengupta, Sandip K.; Whitten, James E.

    2010-01-01

    The stability of self-assembled monolayers (SAMs) at elevated temperatures is of considerable technological importance. The thermal stability of 1-octadecanethiol (ODT), 16-mercaptohexadecanoic acid (MHDA) and 1H,1H,2H,2H-perfluorodecanethiol (PFDT) SAMs on gold surfaces, and of 4-aminobutyltriethoxysilane (ABTES) and 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (PFDS) assembled on hydroxylated silicon surfaces, was studied by X-ray photoelectron spectroscopy (XPS). The samples were heated in ultrahigh vacuum to temperatures in excess of that required for SAM degradation. ODT monolayers were stable to ca. 110 deg. C, while MHDA and PFDT SAMs were stable to ca. 145 deg. C. ABTES SAMs were found to be indefinitely stable to 250 deg. C, while PFDS SAMs were stable to 350 deg. C. These studies demonstrate the advantages of using silane monolayers for moderate to high temperature applications and illustrate differences that arise due to the nature of the tail group. To demonstrate the feasibility of silanes for template-directed patterning, a hydroxylated silicon oxide surface containing microcontact-printed PFDS patterns was spin-coated with a mainly hydrophilic block copolymer. Annealing the surface at 90 deg. C for 2 h caused the block copolymer to dewet the hydrophobic PFDS-patterned regions and adsorb exclusively on the unpatterned regions of the surface.

  3. Analytic tests and their relation to jet fuel thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Heneghan, S.P.; Kauffman, R.E. [Univ. of Dayton Research Institute, OH (United States)

    1995-05-01

    The evaluation of jet fuel thermal stability (TS) by simple analytic procedures has long been a goal of fuels chemists. The reason is obvious: if the analytic chemist can determine which types of material cause his test to respond, the refiners will know which materials to remove to improve stability. Complicating this quest is the lack of an acceptable quantitative TS test with which to compare any analytic procedures. To circumvent this problem, we recently compiled the results of TS tests for 12 fuels using six separate test procedures. The results covering a range of flow and temperature conditions show that TS is not as dependent on test conditions as previously thought. Also, comparing the results from these tests with several analytic procedures shows that either a measure of the number of phenols or the total sulfur present in jet fuels is strongly indicative of the TS. The phenols have been measured using a cyclic voltammetry technique and the polar material by gas chromatography (atomic emission detection) following a solid phase extraction on silica gel. The polar material has been identified as mainly phenols (by mass spectrometry identification). Measures of the total acid number or peroxide concentration have little correlation with TS.

  4. Conductivity study of thermally stabilized RuO2/polythiophene nanocomposites

    Science.gov (United States)

    Hebbar, Vidyashree; Bhajantri, R. F.

    2018-04-01

    The polymer nanocomposites of Ruthenium oxide (RuO2) filled polythiophene (PT) were synthesized by polymerization using chemical method. The purity of the synthesized polymer composite is verified using X-Ray diffraction (XRD). The structural discrepancies of the RuO2 filled PT composites are studied by Fourier transform infrared (FT-IR) spectroscopy. The phase transition and thermal stability of the prepared composite is revised by thermal characterization such as differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The DC conductivity of RuO2 filled PT composite in the form of pellets is calculated using current-voltage (I-V) characterization by two-probe method. The enhancement in conductivity with increased RuO2 content in PT matrix is examined, which is the required property for electrical and electronic applications in supercapacitors.

  5. Electron cyclotron emission from thermal plasmas

    International Nuclear Information System (INIS)

    Fidone, I.; Granata, G.

    1978-02-01

    Electron cyclotron radiation from a warm inhomogeneous plasma is investigated. A direct calculation of the emissive power of a plasma slab is performed using Rytov's method and the result is compared with the solution of the transfer equation. It is found that, for arbitrary directions of emission, the two results differ, which reflects the fact that Kirchhoff's law is not generally obeyed

  6. Electronics in thermal ionisation mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Sattler, E. [Central Bureau for Nuclear Measurements, Geel (Belgium)

    1978-12-15

    The author restricts the discussion to electronic equipment serving for acquisition and handling of analogue measuring data such as: electrometer amplifiers; equipment for digitising the analogue measuring value e.g. voltage-to-frequency converters linked to counter/timer units or digital voltmeters; magnetic field control units.

  7. Thermal injury patterns associated with electronic cigarettes

    OpenAIRE

    Jiwani, Alisha Z; Williams, James F; Rizzo, Julie A; Chung, Kevin K; King, Booker T; Cancio, Leopoldo C

    2017-01-01

    E-cigarettes are typically lithium-ion battery-operated devices that simulate smoking by heating a nicotine-solution into a vapor that the user inhales. E-cigarette use is becoming rapidly popular as an alternative to traditional cigarette smoking. This report describes an emerging problem associated with e-cigarettes, consisting of 10 thermally injured patients seen at a single burn center over a 2-year period from 2014 to 2016. Our cohort was comprised mainly of young adults who sustained m...

  8. Reversed shear Alfven eigenmode stabilization by localized electron cyclotron heating

    Energy Technology Data Exchange (ETDEWEB)

    Van Zeeland, M A; Hyatt, A W; Lohr, J; Petty, C C [General Atomics, PO Box 85608 San Diego, CA 92186-5608 (United States); Heidbrink, W W [University of California-Irvine, Irvine, CA 92697 (United States); Nazikian, R; Solomon, W M; Gorelenkov, N N; Kramer, G J [Princeton Plasma Physics Laboratory, Princeton, NJ 08543-0451 (United States); Austin, M E [University of Texas-Austin, Austin, TX 78712 (United States); Berk, H L [Institute for Fusion Studies, University of Texas at Austin, Austin, TX 78712 (United States); Holcomb, C T; Makowski, M A [Lawrence Livermore National Laboratory, Livermore, CA (United States); McKee, G R [University of Wisconsin-Madison, Madison, WI 53726 (United States); Sharapov, S E [Euratom/UKAEA Fusion Association, Culham, Abingdon, Oxfordshire, OX14 3DB (United Kingdom); Rhodes, T L [University of California-Los Angeles, Los Angeles, California, 90095 (United States)], E-mail: vanzeeland@fusion.gat.com

    2008-03-15

    Reversed shear Alfven eigenmode (RSAE) activity in DIII-D is stabilized by electron cyclotron heating (ECH) applied near the minimum of the magnetic safety factor (q{sub min}) in neutral beam heated discharges with reversed-magnetic shear. The degree of RSAE stabilization, fast ion density and the volume averaged neutron production (S{sub n}) are highly dependent on ECH deposition location relative to q{sub min}. While discharges with ECH stabilization of RSAEs have higher S{sub n} and more peaked fast ion profiles than discharges with significant RSAE activity, neutron production remains strongly reduced (up to 60% relative to TRANSP predictions assuming classical fast ion transport) even when RSAEs are stabilized.

  9. Rectification of electronic heat current by a hybrid thermal diode.

    Science.gov (United States)

    Martínez-Pérez, Maria José; Fornieri, Antonio; Giazotto, Francesco

    2015-04-01

    Thermal diodes--devices that allow heat to flow preferentially in one direction--are one of the key tools for the implementation of solid-state thermal circuits. These would find application in many fields of nanoscience, including cooling, energy harvesting, thermal isolation, radiation detection and quantum information, or in emerging fields such as phononics and coherent caloritronics. However, both in terms of phononic and electronic heat conduction (the latter being the focus of this work), their experimental realization remains very challenging. A highly efficient thermal diode should provide a difference of at least one order of magnitude between the heat current transmitted in the forward temperature (T) bias configuration (Jfw) and that generated with T-bias reversal (Jrev), leading to ℛ = Jfw/Jrev ≫ 1 or ≪ 1. So far, ℛ ≈ 1.07-1.4 has been reported in phononic devices, and ℛ ≈ 1.1 has been obtained with a quantum-dot electronic thermal rectifier at cryogenic temperatures. Here, we show that unprecedentedly high ratios of ℛ ≈ 140 can be achieved in a hybrid device combining normal metals tunnel-coupled to superconductors. Our approach provides a high-performance realization of a thermal diode for electronic heat current that could be successfully implemented in true low-temperature solid-state thermal circuits.

  10. SiC-dopped MCM-41 materials with enhanced thermal and hydrothermal stabilities

    International Nuclear Information System (INIS)

    Wang, Yingyong; Jin, Guoqiang; Tong, Xili; Guo, Xiangyun

    2011-01-01

    Graphical abstract: Novel SiC-dopped MCM-41 materials were synthesized by adding silicon carbide suspension in the molecular sieve precursor solvent followed by in situ hydrothermal synthesis. The dopped materials have a wormhole-like mesoporous structure and exhibit enhanced thermal and hydrothermal stabilities. Highlights: → SiC-dopped MCM-41 was synthesized by in situ hydrothermal synthesis of molecular sieve precursor combined with SiC. → The dopped MCM-41 materials show a wormhole-like mesoporous structure. → The thermal stability of the dopped materials have an increment of almost 100 o C compared with the pure MCM-41. → The hydrothermal stability of the dopped materials is also better than that of the pure MCM-41. -- Abstract: SiC-dopped MCM-41 mesoporous materials were synthesized by the in situ hydrothermal synthesis, in which a small amount of SiC was added in the precursor solvent of molecular sieve before the hydrothermal treatment. The materials were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, N 2 physical adsorption and thermogravimetric analysis, respectively. The results show that the thermal and hydrothermal stabilities of MCM-41 materials can be improved obviously by incorporating a small amount of SiC. The structure collapse temperature of SiC-dopped MCM-41 materials is 100 o C higher than that of pure MCM-41 according to the differential scanning calorimetry analysis. Hydrothermal treatment experiments also show that the pure MCM-41 will losses it's ordered mesoporous structure in boiling water for 24 h while the SiC-dopped MCM-41 materials still keep partial porous structure.

  11. Effects of electron irradiation in space environment on thermal and mechanical properties of carbon fiber/bismaleimide composite

    International Nuclear Information System (INIS)

    Yu, Qi; Chen, Ping; Gao, Yu; Ma, Keming; Lu, Chun; Xiong, Xuhai

    2014-01-01

    Highlights: •Electron irradiation decreased the storage modulus finally. •T g decreased first and then increased and finally decreased. •The thermal stability was reduced and then improved and finally decreased. •The changing trend of flexural strength and ILSS are consistent. -- Abstract: The effects of electron irradiation in simulated space environment on thermal and mechanical properties of high performance carbon fiber/bismaleimide composites were investigated. The dynamic mechanical properties of the composites exposed to different fluences of electron irradiation were evaluated by Dynamic mechanical analysis (DMA). Thermogravimetric analysis was applied to investigate the changes in thermal stability of the resin matrix after exposure to electron irradiation. The changes in mechanical properties of the composites were evaluated by flexural strength and interlaminar shear strength (ILSS). The results indicated that electron irradiation in high vacuum had an impact on thermal and mechanical properties of CF/BMI composites, which depends on irradiation fluence. At lower irradiation fluences less than 5 × 10 15 cm −2 , the dynamic storage modulus, cross-linking degree, thermal stability and mechanical properties that were determined by a competing effect between chain scission and cross-linking process, decreased firstly and then increased. While at higher fluences beyond 5 × 10 15 cm −2 , the chain scission process was dominant and thus led to the degradation in thermal and mechanical properties of the composites

  12. Formation and Thermal Stability of Large Precipitates and Oxides in Titanium and Niobium Microalloyed Steel

    Institute of Scientific and Technical Information of China (English)

    ZHUO Xiao-jun; WOO Dae-hee; WANG Xin-hua; LEE Hae-geon

    2008-01-01

    As-cast CC slabs of microalloyed steels are prone to surface and sub-surface cracking. Precipitation phenomena in-itiated during solidification reduce ductility at high temperature. The unidirectional solidification unit is employed to sim-ulate the solidification process during continuous casting. Precipitation behavior and thermal stability are systemati-cally investigated. Samples of adding titanium and niobium to steels have been examined using field emission scanning electron microscope (FE-SEM), electron probe X-ray microanalyzer (EPMA), and transmission electron microscope (TEM). It has been found that the addition of titanium and niobium to high-strength low-alloyed (HSLA) steel resuited in undesirable large precipitation in the steels, i. e. , precipitation of large precipitates with various morphologies. The composition of the large precipitates has been determined. The effect of cooling rate on (Ti, Nb)(C, N) precipitate formation is investigated. With increasing the cooling rate, titanium-rich (Ti,Nb)(C, N) precipitates are transformed to niobium-rich (Ti,Nb)(C,N) precipitates. The thermal stability of these large precipitates and oxides have been assessed by carrying out various heat treatments such as holding and quenching from temperature at 800 and 1 200 ℃. It has been found that titanium-rich (Ti,Nb)(C,N) precipitate is stable at about 1 200 ℃ and niobi-um-rich (Ti,Nb)(C,N) precipitate is stable at about 800 ℃. After reheating at 1 200 ℃ for 1 h, (Ca, Mn)S and TiN are precipitated from Ca-Al oxide. However, during reheating at 800 ℃ for 1 h, Ca-Al-Ti oxide in specimens was stable. The thermodynamic calculation of simulating the thermal process is employed. The calculation results are in good agreement with the experimental results.

  13. Thermalization of secondary electrons under AMSGEMP conditions

    International Nuclear Information System (INIS)

    Bloomberg, H.W.; Pine, V.W.

    1984-01-01

    A Monte Carlo algorithm is used to determine the time behavior of source secondary electrons for ranges of the electric field to pressure ratio E/p of interest in AMSGEMP. The algorithm contains a very detailed cross section set describing electron interactions with the background gas. The authors show that the delay in the attainment of the peak time independent ionization frequency (or ionization coefficient) may result in negligible ionization over times of interest. In any case the behavior is shown to behave much differently than in examples where limited cross section sets, common in currently employed predictive codes, are employed. In particular, the importance of momentum transfer is indicated. A critique of the scaling implications of the phenomena is made

  14. Laboratory electron exposure of TSS-1 thermal control coating

    Science.gov (United States)

    Vaughn, J. A.; Mccollum, M.; Carruth, M. R., Jr.

    1995-01-01

    RM400, a conductive thermal control coating, was developed for use on the exterior shell of the tethered satellite. Testing was performed by the Engineering Physics Division to quantify effects of the space environment on this coating and its conductive and optical properties. Included in this testing was exposure of RM400 to electrons with energies ranging from 0.1 to 1 keV, to simulate electrons accelerated from the ambient space plasma when the tethered satellite is fully deployed. During this testing, the coating was found to luminesce, and a prolonged exposure of the coating to high-energy electrons caused the coating to darken. This report describes the tests done to quantify the degradation of the thermal control properties caused by electron exposure and to measure the luminescence as a function of electron energy and current density to the satellite.

  15. Thermal Design of Power Electronic Circuits

    CERN Document Server

    Künzi, R.

    2015-06-15

    The heart of every switched mode converter consists of several switching semiconductor elements. Due to their non-ideal behaviour there are ON state and switching losses heating up the silicon chip. That heat must effectively be transferred to the environment in order to prevent overheating or even destruction of the element. For a cost-effective design, the semiconductors should be operated close to their thermal limits. Unfortunately the chip temperature cannot be measured directly. Therefore a detailed understanding of how losses arise, including their quantitative estimation, is required. Furthermore, the heat paths to the environment must be understood in detail. This paper describes the main issues of loss generation and its transfer to the environment and how it can be estimated by the help of datasheets and/or experiments.

  16. Thermal injury patterns associated with electronic cigarettes.

    Science.gov (United States)

    Jiwani, Alisha Z; Williams, James F; Rizzo, Julie A; Chung, Kevin K; King, Booker T; Cancio, Leopoldo C

    2017-01-01

    E-cigarettes are typically lithium-ion battery-operated devices that simulate smoking by heating a nicotine-solution into a vapor that the user inhales. E-cigarette use is becoming rapidly popular as an alternative to traditional cigarette smoking. This report describes an emerging problem associated with e-cigarettes, consisting of 10 thermally injured patients seen at a single burn center over a 2-year period from 2014 to 2016. Our cohort was comprised mainly of young adults who sustained mixed partial and full thickness burns as a result of e-cigarette-related explosions. In many documented scenarios, a malfunctioning or over-heated battery is the cause. Our data support the need for increased awareness among healthcare providers and the general public of the potential harms of e-cigarette use, modification, storage, and charging.

  17. The analysis of thermal stability of detonation nanodiamond

    International Nuclear Information System (INIS)

    Efremov, V P; Zakatilova, E I

    2016-01-01

    The detonation nanodiamond is a new perspective material. Ammunition recycling with use of high explosives and obtaining nanodiamond as the result of the detonation synthesis have given a new motivation for searching of their application areas. In this work nanodiamond powder has been investigated by the method of synchronous thermal analysis. Experiments have been carried out at atmospheric pressure in the environment of argon. Nanodiamond powder has been heated in the closed corundum crucible at the temperature range of 30-1500 °C. The heating rates were varied from 2 K/min to 20 K/min. After the heat treatment, the samples have been studied by the x-ray diffraction and the electron microscopy. As one of the results of this work, it has been found that the detonation nanodiamond has not started the transition into graphite at the temperature below 800 °C. (paper)

  18. The analysis of thermal stability of detonation nanodiamond

    Science.gov (United States)

    Efremov, V. P.; Zakatilova, E. I.

    2016-11-01

    The detonation nanodiamond is a new perspective material. Ammunition recycling with use of high explosives and obtaining nanodiamond as the result of the detonation synthesis have given a new motivation for searching of their application areas. In this work nanodiamond powder has been investigated by the method of synchronous thermal analysis. Experiments have been carried out at atmospheric pressure in the environment of argon. Nanodiamond powder has been heated in the closed corundum crucible at the temperature range of 30-1500 °C. The heating rates were varied from 2 K/min to 20 K/min. After the heat treatment, the samples have been studied by the x-ray diffraction and the electron microscopy. As one of the results of this work, it has been found that the detonation nanodiamond has not started the transition into graphite at the temperature below 800 °C.

  19. Power Electronics Thermal Management R&D: Annual Report

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, Gilbert [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-04-08

    The objective for this project is to develop thermal management strategies to enable efficient and high-temperature wide-bandgap (WBG)-based power electronic systems (e.g., emerging inverter and DC-DC converter). Device- and system-level thermal analyses are conducted to determine the thermal limitations of current automotive power modules under elevated device temperature conditions. Additionally, novel cooling concepts and material selection will be evaluated to enable high-temperature silicon and WBG devices in power electronics components. WBG devices (silicon carbide [SiC], gallium nitride [GaN]) promise to increase efficiency, but will be driven as hard as possible. This creates challenges for thermal management and reliability.

  20. Application of phase change materials in thermal management of electronics

    International Nuclear Information System (INIS)

    Kandasamy, Ravi; Wang Xiangqi; Mujumdar, Arun S.

    2007-01-01

    Application of a novel PCM package for thermal management of portable electronic devices was investigated experimentally for effects of various parameters e.g. power input, orientation of package, and various melting/freezing times under cyclic steady conditions. Also, a two-dimensional numerical study was made and compared the experimental results. Results show that increased power inputs increase the melting rate, while orientation of the package to gravity has negligible effect on the thermal performance of the PCM package. The thermal resistance of the device and the power level applied to the PCM package are of critical importance for design of a passive thermal control system. Comparison with numerical results confirms that PCM-based design is an excellent candidate design for transient electronic cooling applications

  1. The stabilities and electron structures of Al-Mg clusters with 18 and 20 valence electrons

    Science.gov (United States)

    Yang, Huihui; Chen, Hongshan

    2017-07-01

    The spherical jellium model predicts that metal clusters having 18 and 20 valence electrons correspond to the magic numbers and will show specific stabilities. We explore in detail the geometric structures, stabilities and electronic structures of Al-Mg clusters containing 18 and 20 valence electrons by using genetic algorithm combined with density functional theories. The stabilities of the clusters are governed by the electronic configurations and Mg/Al ratios. The clusters with lower Mg/Al ratios are more stable. The molecular orbitals accord with the shell structures predicted by the jellium model but the 2S level interweaves with the 1D levels and the 2S and 1D orbitals form a subgroup. The clusters having 20 valence electrons form closed 1S21P61D102S2 shells and show enhanced stability. The Al-Mg clusters with a valence electron count of 18 do not form closed shells because one 1D orbital is unoccupied. The ionization potential and electron affinity are closely related to the electronic configurations; their values are determined by the subgroups the HOMO or LUMO belong to. Supplementary material in the form of one pdf file available from the Journal web page at http://https://doi.org/10.1140/epjd/e2017-80042-9

  2. Phase evolution and thermal properties of yttria-stabilized hafnia nano-coatings deposited on alumina

    Science.gov (United States)

    Rubio, Ernesto Javier

    High-temperature coatings are critical to the future power-generation systems and industries. Thermal barrier coatings (TBCs), which are usually the ceramic materials applied as thin coatings, protect engine components and allow further increase in engine temperatures for higher efficiency. Thus, the durability and reliability of the coating systems have to be more robust compared to current natural gas based engines. While a near and mid-term target is to develop TBC architecture with a 1300 °C surface temperature tolerance, a deeper understanding of the structure evolution and thermal behavior of the TBC-bond coat interface, specifically the thermally grown oxide (TGO), is of primary importance. In the present work, attention is directed towards yttria-stabilized hafnia (YSH) coatings on alumina (α-Al2O 3) to simulate the TBC-TGO interface and understand the phase evolution, microstructure and thermal oxidation of the coatings. YSH coatings were grown on α-Al2O3 substrates by sputter deposition by varying coating thickness in a wide range ˜30-1000 nm. The effect of coating thickness on the structure, morphology and the residual stress has been investigated using X-ray diffraction (XRD) and high resolution scanning electron microscopy (SEM). Thermal oxidation behavior of the coatings has been evaluated using the isothermal oxidation measurements under static conditions. X-ray diffraction analyses revealed the existence of monoclinic hafnia phase for relatively thin coatings indicating that the interfacial phenomena are dominant in phase stabilization. The evolution towards pure stabilized cubic phase of hafnia with the increasing coating thickness is observed. The SEM results indicate the changes in morphology of the coatings; the average grain size increases from 15 to 500 nm with increasing thickness. Residual stress was calculated employing XRD using the variable ψ-angle. Relation between residual stress and structural change is also studied. The results

  3. Power Electronics Thermal Management R&D (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Waye, S.

    2014-11-01

    This project will investigate and develop thermal-management strategies for wide bandgap (WBG)-based power electronics systems. Research will be carried out to deal with thermal aspects at the module- and system-level. Module-level research will focus on die- and substrate-integrated cooling strategies and heat-transfer enhancement technologies. System-level research will focus on thermal-management strategies for the entire power electronics system to enable smart packaging solutions. One challenge with WBG device-based power electronics is that although losses in the form of heat may be lower, the footprint of the components is also likely to be reduced to reduce cost, weight, and volume. Combined with higher operational temperatures, this creates higher heat fluxes which much be removed from a smaller footprint, requiring advanced cooling strategies.

  4. Thermal Electrons in Gamma-Ray Burst Afterglows

    Energy Technology Data Exchange (ETDEWEB)

    Ressler, Sean M.; Laskar, Tanmoy [Department of Astronomy, University of California, 501 Campbell Hall, Berkeley, CA 94720-3411 (United States)

    2017-08-20

    To date, nearly all multi-wavelength modeling of long-duration γ -ray bursts has ignored synchrotron radiation from the significant population of electrons expected to pass the shock without acceleration into a power-law distribution. We investigate the effect of including the contribution of thermal, non-accelerated electrons to synchrotron absorption and emission in the standard afterglow model, and show that these thermal electrons provide an additional source of opacity to synchrotron self-absorption, and yield an additional emission component at higher energies. The extra opacity results in an increase in the synchrotron self-absorption frequency by factors of 10–100 for fiducial parameters. The nature of the additional emission depends on the details of the thermal population, but is generally observed to yield a spectral peak in the optical brighter than radiation from the nonthermal population by similar factors a few seconds after the burst, remaining detectable at millimeter and radio frequencies several days later.

  5. Energy loss and thermalization of low-energy electrons

    International Nuclear Information System (INIS)

    LaVerne, J.A.; Mozumder, A.; Notre Dame Univ., IN

    1984-01-01

    Various processes involved in the moderation of low-energy electrons (< 10 keV in energy) have been delineated in gaseous and liquid media. The discussion proceeds in two stages. The first stage ends and the second stage begins when the electron energy equals the first excitation potential of the medium. The second stage ends with thermalization. Cross sections for electronic excitation and for the excitation (and de-excitation) of sub-electronic processes have been evaluated and incorporated in suitable stopping power and transport theories. Comparison between experiment and theory and intercomparisons between theories and experiments have been provided where possible. (author)

  6. Bis(triisopropylsilylethynyl)pentacene/Au(111) interface: Coupling, molecular orientation, and thermal stability

    KAUST Repository

    Gnoli, Andrea; Ü stü nel, Hande; Toffoli, Daniele; Yu, Liyang; Catone, D.; Turchini, Stefano; Lizzit, Silvano; Stingelin, Natalie; Larciprê te, Rosanna

    2014-01-01

    The assembly and the orientation of functionalized pentacene at the interface with inorganics strongly influence both the electric contact and the charge transport in organic electronic devices. In this study electronic spectroscopies and theoretical modeling are combined to investigate the properties of the bis(triisopropylsilylethynyl)pentacene (TIPS-Pc)/Au(111) interface as a function of the molecular coverage to compare the molecular state in the gas phase and in the adsorbed phase and to determine the thermal stability of TIPS-Pc in contact with gold. Our results show that in the free molecule only the acene atoms directly bonded to the ligands are affected by the functionalization. Adsorption on Au(111) leads to a weak coupling which causes only modest binding energy shifts in the TIPS-Pc and substrate core level spectra. In the first monolayer the acene plane form an angle of 33 ± 2° with the Au(111) surface at variance with the vertical geometry reported for thicker solution-processed or evaporated films, whereas the presence of configurational disorder was observed in the multilayer. The thermal annealing of the TIPS-Pc/Au(111) interface reveals the ligand desorption at ∼470 K, which leaves the backbone of the decomposed molecule flat-lying on the metal surface as in the case of the unmodified pentacene. The weak interaction with the metal substrate causes the molecular dissociation to occur 60 K below the thermal decomposition taking place in thick drop-cast films.

  7. Bis(triisopropylsilylethynyl)pentacene/Au(111) interface: Coupling, molecular orientation, and thermal stability

    KAUST Repository

    Gnoli, Andrea

    2014-10-02

    The assembly and the orientation of functionalized pentacene at the interface with inorganics strongly influence both the electric contact and the charge transport in organic electronic devices. In this study electronic spectroscopies and theoretical modeling are combined to investigate the properties of the bis(triisopropylsilylethynyl)pentacene (TIPS-Pc)/Au(111) interface as a function of the molecular coverage to compare the molecular state in the gas phase and in the adsorbed phase and to determine the thermal stability of TIPS-Pc in contact with gold. Our results show that in the free molecule only the acene atoms directly bonded to the ligands are affected by the functionalization. Adsorption on Au(111) leads to a weak coupling which causes only modest binding energy shifts in the TIPS-Pc and substrate core level spectra. In the first monolayer the acene plane form an angle of 33 ± 2° with the Au(111) surface at variance with the vertical geometry reported for thicker solution-processed or evaporated films, whereas the presence of configurational disorder was observed in the multilayer. The thermal annealing of the TIPS-Pc/Au(111) interface reveals the ligand desorption at ∼470 K, which leaves the backbone of the decomposed molecule flat-lying on the metal surface as in the case of the unmodified pentacene. The weak interaction with the metal substrate causes the molecular dissociation to occur 60 K below the thermal decomposition taking place in thick drop-cast films.

  8. HR-EELS study of hydrogen bonding configuration, chemical and thermal stability of detonation nanodiamond films

    Energy Technology Data Exchange (ETDEWEB)

    Michaelson, Sh.; Akhvlediani, R. [Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Petit, T.; Girard, H.A.; Arnault, J.C. [CEA, LIST, Diamond Sensors Laboratory, F-91191 Gif sur Yvette (France); Hoffman, A., E-mail: choffman@tx.technion.ac.il [Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000 (Israel)

    2014-06-01

    Nano-diamond films composed of 3–10 nm grains prepared by the detonation method and deposited onto silicon substrates by drop-casting were examined by high resolution electron energy loss spectroscopy (HR-EELS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and secondary ion mass spectroscopy (SIMS). The impact of (i) ex-situ ambient annealing at 400 °C and (ii) ex-situ hydrogenation on hydrogen bonding and its thermal stability were examined. In order to clarify the changes in hydrogen bonding configuration detected on the different surfaces as a function of thermal annealing, in-situ hydrogenation by thermally activated atomic hydrogen was performed and examined. This study provides direct evidence that the exposure to ambient conditions and medium temperature ambient annealing have a pronounced effect on the hydrogen-carbon bonding configuration onto the nano-diamond surfaces. In-situ 1000 °C annealing results in irreversible changes of the film surface and partial nano-diamond silicidation.

  9. Reflection of oblique electron thermal modes in an inhomogeneous plasma

    International Nuclear Information System (INIS)

    Ohnuma, T.; Watanabe, T.; Sanuki, H.

    1980-04-01

    In an inhomogeneous magnetoplasma, reflection of an oblique electron thermal mode radiated from a local source is investigated experimentally and theoretically near the electron plasma frequency layer. The experimental observation of reflection in the lower plasma density region than the f sub(p)-layer is found to be in qualitative accord with the theoretical reflection, which is obtained from a kinetic theory in an inhomogeneous magnetoplasma. The reflection of the thermal mode is also compared with that of an electromagnetic mode at the f sub(p)-layer. (author)

  10. The influence of oxygen contamination on the thermal stability and hardness of nanocrystalline Ni–W alloys

    Energy Technology Data Exchange (ETDEWEB)

    Marvel, Christopher J., E-mail: cjm312@lehigh.edu [Department of Materials Science and Engineering, Lehigh University, Bethlehem, PA 18015 (United States); Yin, Denise [Department of Materials Science and Engineering, Lehigh University, Bethlehem, PA 18015 (United States); Cantwell, Patrick R. [Department of Mechanical Engineering, Rose-Hulman Institute of Technology, Terre Haute, IN 47803 (United States); Harmer, Martin P. [Department of Materials Science and Engineering, Lehigh University, Bethlehem, PA 18015 (United States)

    2016-05-10

    Nanocrystalline Ni–W alloys are reported in the literature to be stabilized against high temperature grain growth by W-segregation at the grain boundaries. However, alternative thermal stability mechanisms have been insufficiently investigated, especially in the presence of impurities. This study explored the influence of oxygen impurities on the thermal stability and mechanical properties of electrodeposited Ni-23 at% W with aberration-corrected scanning transmission electron microscopy (STEM) and nanoindentation hardness testing. The primary finding of this study was that nanoscale oxides were of sufficient size and volume fraction to inhibit grain growth. The oxide particles were predominantly located on grain boundaries and triple points, which strongly suggests that a particle drag mechanism was active during annealing. In addition, W-segregation was observed at the oxide/Ni(W) interfaces rather than the presumed Ni(W) grain boundaries, further supporting the argument that alternative mechanisms are responsible for thermal stability in these alloys. Lastly, alloys with nanoscale oxides exhibited a higher hardness compared to similar alloys without oxides, suggesting that the particles are widely advantageous. Overall, this work demonstrates that impurity oxide particles can limit grain growth, and alternative mechanisms may be responsible for Ni–W thermal stability.

  11. Enhanced coercivity thermal stability realized in Nd–Fe–B thin films diffusion-processed by Nd–Co alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Hui; Fu, Yanqing [Key laboratory of electromagnetic processing of materials (EPM), Ministry of Education, Northeastern University, Shenyang 110819 (China); Department of Physics and Chemistry of Materials, School of Materials Science and Engineering, Northeastern University, Shenyang 110819 (China); Li, Guojian; Liu, Tie [Key laboratory of electromagnetic processing of materials (EPM), Ministry of Education, Northeastern University, Shenyang 110819 (China); Cui, Weibin, E-mail: cuiweibin@epm.neu.edu.cn [Key laboratory of electromagnetic processing of materials (EPM), Ministry of Education, Northeastern University, Shenyang 110819 (China); Department of Physics and Chemistry of Materials, School of Materials Science and Engineering, Northeastern University, Shenyang 110819 (China); Liu, Wei; Zhang, Zhidong [Shenyang National Laboratory for Materials Science, Institute of Metal Research (IMR), Chinese Academy of Sciences (CAS), Shenyang 110016 (China); Wang, Qiang, E-mail: wangq@mail.neu.edu.cn [Key laboratory of electromagnetic processing of materials (EPM), Ministry of Education, Northeastern University, Shenyang 110819 (China)

    2017-03-15

    A proposed Nd{sub 2}Fe{sub 14}B-core/Nd{sub 2}(Fe, Co){sub 14}B-shell microstructure was realized by diffusion-processing textured Nd{sub 14}Fe{sub 77}B{sub 9} single-layer film with Nd{sub 100−x}Co{sub x} (x=10, 20 and 40) alloys to improve the coercivity thermal stability. The ambient coercivity was increased from around 1 T in single-layer film to nearly 2 T in diffusion-processed films, which was due to the Nd-rich grain boundaries as seen from transmission electron microscopy (TEM) images. The coercivity thermal stability was improved by the core/shell microstructure because Nd-rich grain boundaries provided the high ambient coercivity and Co-rich shell provided the improved coercivity stability. - Highlights: • Core–shell microstructure proposed for enhancing the coercivity thermal stability. • Coercivity enhanced to nearly 2 T by diffusion-processing with Nd–Co alloy. • Good squareness and highly textured microstructure obtained. • Nd-rich phases observed by TEM after diffusion process. • Coercivity thermal stability improved with minor Co addition in grain boundary regions.

  12. Automotive mechatronics automotive networking, driving stability systems, electronics

    CERN Document Server

    2015-01-01

    As the complexity of automotive vehicles increases this book presents operational and practical issues of automotive mechatronics. It is a comprehensive introduction to controlled automotive systems and provides detailed information of sensors for travel, angle, engine speed, vehicle speed, acceleration, pressure, temperature, flow, gas concentration etc. The measurement principles of the different sensor groups are explained and examples to show the measurement principles applied in different types. Contents Basics of mechatronics.- Architecture.- Electronic control unit.- Software development.- Basic principles of networking.- Automotive networking.- Bus systems.- Automotive sensors.- Sensor measuring principles.- Sensor types.- Electric actuators.- Electrohydraulic actuators.- Electronic transmission control.- Electronic transmission control unit.- Modules for transmission control.- Antilock braking system.- Traction control system.- Electronic stability program.- Automatic brake functions.- Hydraulic modu...

  13. Thermal Stability and Flammability of Styrene-Butadiene Rubber-Based (SBR Ceramifiable Composites

    Directory of Open Access Journals (Sweden)

    Rafał Anyszka

    2016-07-01

    Full Text Available Ceramifiable styrene-butadiene (SBR-based composites containing low-softening-point-temperature glassy frit promoting ceramification, precipitated silica, one of four thermally stable refractory fillers (halloysite, calcined kaolin, mica or wollastonite and a sulfur-based curing system were prepared. Kinetics of vulcanization and basic mechanical properties were analyzed and added as Supplementary Materials. Combustibility of the composites was measured by means of cone calorimetry. Their thermal properties were analyzed by means of thermogravimetry and specific heat capacity determination. Activation energy of thermal decomposition was calculated using the Flynn-Wall-Ozawa method. Finally, compression strength of the composites after ceramification was measured and their micromorphology was studied by scanning electron microscopy. The addition of a ceramification-facilitating system resulted in the lowering of combustibility and significant improvement of the thermal stability of the composites. Moreover, the compression strength of the mineral structure formed after ceramification is considerably high. The most promising refractory fillers for SBR-based ceramifiable composites are mica and halloysite.

  14. The Effect of Ultrasonic Treatment on Thermal Stability of the Cured Epoxy/Layered Silicate Nanocomposite

    Directory of Open Access Journals (Sweden)

    N. Y. Yuhana

    2012-01-01

    Full Text Available The effect of ultrasonic treatment on thermal stability of binary systems containing epoxy and organic chemically modified montmorillonite (Cloisite 30B was studied. Differential scanning calorimetry (DSC, thermal gravimetric analysis (TGA, transmission electron microscopy (TEM, and wide angle X-ray diffraction (WAXD analysis were utilized. The mixing of epoxy and Cloisite 30B nanocomposites was performed by mechanical stirring, followed by 1 or 3-hour ultrasonic treatment, and polyetheramine as the curing agent. Both XRD and TEM analyses confirmed that the intercalation of Cloisite 30B was achieved. The d0 spacings for silicate in cured sample prepared at 1- and 3-hour duration of ultrasonic treatment were about 21 and 18 Å, respectively. This shows that shorter duration or ultrasonic treatment may be preferable to achieve higher d0 spacing of clay. This may be attributed to the increase in viscosity as homopolymerization process occurred, which restricts silicate dispersion. The 1-hour sonicated samples seem to be more thermally stable during the glass transition, but less stable during thermal decomposition process.

  15. Adsorptive properties and thermal stability of carbon fibers modified by boron and phosphorus compounds

    International Nuclear Information System (INIS)

    Malygin, A.A.; Postnova, A.M.; Shevchenko, G.K.

    1996-01-01

    Sorptional characteristics as regards water vapors and thermal stability of carbon fibers modified by method of molecular superposition of borohydroxide groupings have been studied. Sorptional activity in the range of low and medium relative pressures of water vapors in modified samples increases several times, while thermal stability of carbon fiber increases, as well. 14 refs.; 1 fig.; 1 tab

  16. Nonlinear electron-acoustic rogue waves in electron-beam plasma system with non-thermal hot electrons

    Science.gov (United States)

    Elwakil, S. A.; El-hanbaly, A. M.; Elgarayh, A.; El-Shewy, E. K.; Kassem, A. I.

    2014-11-01

    The properties of nonlinear electron-acoustic rogue waves have been investigated in an unmagnetized collisionless four-component plasma system consisting of a cold electron fluid, non-thermal hot electrons obeying a non-thermal distribution, an electron beam and stationary ions. It is found that the basic set of fluid equations is reduced to a nonlinear Schrodinger equation. The dependence of rogue wave profiles on the electron beam and energetic population parameter are discussed. The results of the present investigation may be applicable in auroral zone plasma.

  17. Pyroprotein-Based Electronic Textiles with High Stability.

    Science.gov (United States)

    Jeon, Jun Woo; Cho, Se Youn; Jeong, Yu Jin; Shin, Dong Seok; Kim, Na Rae; Yun, Young Soo; Kim, Hyun-Tae; Choi, Soo Bong; Hong, Won G; Kim, Hae Jin; Jin, Hyoung-Joon; Kim, Byung Hoon

    2017-02-01

    Thermally reducible pyroprotein-based electronic textiles (e-textiles) are fabricated using graphene oxide and a pyroprotein such as cocoon silk and spider web without any chemical agents. The electrical conductivity of the e-textile is 11.63 S cm -1 , which is maintained even in bending, washing, and temperature variation. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Effect of carbon nanospheres on shape stabilization and thermal behavior of phase change materials for thermal energy storage

    International Nuclear Information System (INIS)

    Mehrali, Mohammad; Tahan Latibari, Sara; Mehrali, Mehdi; Mahlia, Teuku Meurah Indra; Cornelis Metselaar, Hendrik Simon

    2014-01-01

    Highlights: • Introducing novel form-stable PCM of stearic acid (SA)/carbon nanospheres (CNSs). • The highest stabilized SA content is 83 wt% in the SA/CNS composites. • Increasing thermal conductivity of composite phase change material with high amount of latent heat. - Abstract: Stearic acid (SA) is one of the main phase change materials (PCMs) for medium temperature thermal energy storage systems. In order to stabilize the shape and enhance the thermal conductivity of SA, the effects of adding carbon nanospheres (CNSs) as a carbon nanofiller were examined experimentally. The maximum mass fraction of SA retained in CNSs was found as 80 wt% without the leakage of SA in a melted state, even when it was heated over the melting point of SA. The dropping point test shows that there was clearly no liquid leakage through the phase change process at the operating temperature range of the composite PCMs. The thermal stability and thermal properties of composite PCMs were investigated with a thermogravimetric analyzer (TGA) and differential scanning calorimeter (DSC), respectively. The thermal conductivity of the SA/CNS composite was determined by the laser flash method. The thermal conductivity at 35 °C increased about 105% for the highest loading of CNS (50 wt%). The thermal cycling test proved that form-stable composite PCMs had good thermal reliability and chemical durability after 1000 cycles of melting and freezing, which is advantageous for latent heat thermal energy storage (LHTES)

  19. Thermal behavior of aerosol particles from biomass burning during the BBOP campaign using transmission electron microscopy

    Science.gov (United States)

    Adachi, K.; Ishimoto, H.; Sedlacek, A. J., III; Kleinman, L. I.; Chand, D.; Hubbe, J. M.; Buseck, P. R.

    2017-12-01

    Aerosol samples were collected from wildland and agricultural biomass fires in North America during the 2013 Biomass Burning Observation Project (BBOP). We show in-situ shape and size changes and variations in the compositions of individual particles before and after heating using a transmission electron microscope (TEM). The responses of aerosol particles to heating are important for measurements of their chemical, physical, and optical properties, classification, and determination of origin. However, the thermal behavior of organic aerosol particles is largely unknown. We provide a method to analyze such thermal behavior through heating from room temperature to >600°C by using a heating holder within TEM. The results indicate that individual tar balls (TB; spherical organic material) from biomass burning retained, on average, up to 30% of their volume when heated to 600°C. Chemical analysis reveals that K and Na remained in the residues, whereas S and O were lost. In contrast to bulk sample measurements of carbonaceous particles using thermal/optical carbon analyzers, our single-particle results imply that many individual organic particles consist of multiple types of organic matter having different thermal stabilities. Our results also suggest that because of their thermal stability, some organic particles may not be detectable by using aerosol mass spectrometry or thermal/optical carbon analyzers. This result can lead to an underestimate of the abundance of TBs and other organic particles, and therefore biomass burning may have a greater influence than is currently recognized in regional and global climate models.

  20. Electrostatic stability of electron-positron plasmas in dipole geometry

    Science.gov (United States)

    Mishchenko, Alexey; Plunk, Gabriel G.; Helander, Per

    2018-04-01

    The electrostatic stability of electron-positron plasmas is investigated in the point-dipole and Z-pinch limits of dipole geometry. The kinetic dispersion relation for sub-bounce-frequency instabilities is derived and solved. For the zero-Debye-length case, the stability diagram is found to exhibit singular behaviour. However, when the Debye length is non-zero, a fluid mode appears, which resolves the observed singularity, and also demonstrates that both the temperature and density gradients can drive instability. It is concluded that a finite Debye length is necessary to determine the stability boundaries in parameter space. Landau damping is investigated at scales sufficiently smaller than the Debye length, where instability is absent.

  1. Thermoelectric properties and thermal stability of Bi-doped PbTe single crystal

    Science.gov (United States)

    Chen, Zhong; Li, Decong; Deng, Shuping; Tang, Yu; Sun, Luqi; Liu, Wenting; Shen, Lanxian; Yang, Peizhi; Deng, Shukang

    2018-06-01

    In this study, n-type Bi-doped single-crystal PbTe thermoelectric materials were prepared by melting and slow cooling method according to the stoichiometric ratio of Pb:Bi:Te = 1-x:x:1 (x = 0, 0.1, 0.15, 0.2, 0.25). The X-ray diffraction patterns of Pb1-xBixTe samples show that all main diffraction peaks are well matched with the PbTe matrix, which has a face-centered cubic structure with the space group Fm 3 bar m . Electron probe microanalysis reveals that Pb content decreases gradually, and Te content remains invariant basically with the increase of Bi content, indicating that Bi atoms are more likely to replace Pb atoms. Thermal analysis shows that the prepared samples possess relatively high thermal stability. Simultaneously, transmission electron microscopy and selected area electron diffraction pattern indicate that the prepared samples have typical single-crystal structures with good mechanical properties. Moreover, the electrical conductivity of the prepared samples improved significantly compared with that of the pure sample, and the maximum ZT value of 0.84 was obtained at 600 K by the sample with x = 0.2.

  2. Thermal stability of the superalloys Inconel 625 and Nimonic 86

    International Nuclear Information System (INIS)

    Kohl, H.K.; Peng, K.

    1981-01-01

    The thermal stability of Inconel 625 and Nimonic 86, as received, cold worked (10, 20, and 40%), and solution treated, was investigated in the temperature range 500-900 0 C. The annealing times varied from 0.3 (0.03) to 100 days. Precipitation hardening and recovery (recrystallisation) takes place in cold worked material, beginning after shorter times in cold worked material than in as received material. The temperature interval for precipitation hardening is extended in Nimonic 86, due to cold working, from about 500-600 0 C to about 450-700 0 C. It is possible to suppress or retard the precipitation hardening in solution treated Inconel 625 and Nimonic 86 by fast cooling after solution annealing. Hardness was measured at room temperature with five different loads, so that the parameters k and n from Meyer's-law, and the Brinell hardness number (for F / D 2 = 30) could be determined. The lattice contraction of Inconel 625 due to ageing was investigated with X-ray measurements. The change of intensities of the diffractometer traces due to recovery was also determined. (orig.)

  3. Thermal stability of simple tetragonal and hexagonal diamond germanium

    Science.gov (United States)

    Huston, L. Q.; Johnson, B. C.; Haberl, B.; Wong, S.; Williams, J. S.; Bradby, J. E.

    2017-11-01

    Exotic phases of germanium, that form under high pressure but persist under ambient conditions, are of technological interest due to their unique optical and electrical properties. The thermal evolution and stability of two of these exotic Ge phases, the simple tetragonal (st12) and hexagonal diamond (hd) phases, are investigated in detail. These metastable phases, formed by high pressure decompression in either a diamond anvil cell or by nanoindentation, are annealed at temperatures ranging from 280 to 320 °C for st12-Ge and 200 to 550 °C for hd-Ge. In both cases, the exotic phases originated from entirely pure Ge precursor materials. Raman microspectroscopy is used to monitor the phase changes ex situ following annealing. Our results show that hd-Ge synthesized via a pure form of a-Ge first undergoes a subtle change in structure and then an irreversible phase transformation to dc-Ge with an activation energy of (4.3 ± 0.2) eV at higher temperatures. St12-Ge was found to transform to dc-Ge with an activation energy of (1.44 ± 0.08) eV. Taken together with results from previous studies, this study allows for intriguing comparisons with silicon and suggests promising technological applications.

  4. Experimental study of the thermal stability of hydrocarbon fuels

    Science.gov (United States)

    Marteney, P. J.; Colket, M. B.; Vranos, A.

    1982-01-01

    The thermal stability of two hydrocarbon fuels (premium diesel and regular diesel) was determined in a flow reactor under conditions representing operation of an aircraft gas turbine engine. Temperature was varied from 300 to 750 F (422 to 672 K) for fuel flows of 2.84 to 56.8 liters/hr (corresponding to 6.84 x 0.00010 to 1.63 x 0.010 kg/sec for regular diesel fuel and 6.55 x 0.00010 to 1.37 x 0.010 kg/sec for premium diesel fuel); test times varied between 1 and 8 hr. The rate of deposition was obtained through measurement of weight gained by metal discs fixed along the channel wall. The rate of deposit formation is best correlated by an Arrhenius expression. The sample discs in the flow reactor were varied among stainless steel, aluminum and brass; fuels were doped with quinoline, indole, and benzoyl perioxide to yield nitrogen or oxygen concentrations of approximately 1000 ppm. The most substantial change in rate was an increase in deposits for brass discs; other disc materials or the additives caused only small perturbations. Tests were also conducted in a static reactor at temperatures of 300 to 800 F for times of 30 min to 2 1/2 hr. Much smaller deposition was found, indicating the importance of fluid transport in the mechanism.

  5. Thermal stability of the immobilized fructosyltransferase from Rhodotorula sp

    Directory of Open Access Journals (Sweden)

    E Aguiar-Oliveira

    2011-09-01

    Full Text Available The thermal stability of the extracellular fructosyltransferase (FTase from Rhodotorula sp., recovered from cultivation medium by ethanol precipitation and immobilized onto niobium ore, was studied by Arrhenius plot, half - life profile, half - inactivation temperature (T50 and thermodynamic parameters. The Arrhenius plot showed two different behaviors with different deactivation energies (Ead only after immobilization, the transition occurring in the temperature interval between 51 and 52ºC. T50 for the free enzyme was estimated to be around 62ºC and, after immobilization, 66ºC. After 15 minutes at 52ºC, it was also possible to observe enzymatic activation for both the free and immobilized forms, but greater activation was achieved at pH 4.5 with the immobilized enzyme. Between 47 - 51ºC the immobilized enzyme was more stable than the free enzyme, with pH 6.0 being the more stable condition for the immobilized enzyme. However, above 52ºC the free form was more stable.

  6. Modelling of non-thermal electron cyclotron emission during ECRH

    International Nuclear Information System (INIS)

    Tribaldos, V.; Krivenski, V.

    1990-01-01

    The existence of suprathermal electrons during Electron Cyclotron Resonance Heating experiments in tokamaks is today a well established fact. At low densities the creation of large non-thermal electron tails affects the temperature profile measurements obtained by 2 nd harmonic, X-mode, low-field side, electron cyclotron emission. At higher densities suprathermal electrons can be detected by high-field side emission. In electron cyclotron current drive experiments a high energy suprathermal tail, asymmetric in v, is observed. Non-Maxwellian electron distribution functions are also typically observed during lower-hybrid current drive experiments. Fast electrons have been observed during ionic heating by neutral beams as well. Two distinct approaches are currently used in the interpretation of the experimental results: simple analytical models which reproduce some of the expected non-Maxwellian characteristics of the electron distribution function are employed to get a qualitative picture of the phenomena; sophisticated numerical Fokker-Planck calculations give the electron distribution function from which the emission spectra are computed. No algorithm is known to solve the inverse problem, i.e. to compute the electron distribution function from the emitted spectra. The proposed methods all relay on the basic assumption that the electron distribution function has a given functional dependence on a limited number of free parameters, which are then 'measured' by best fitting the experimental results. Here we discuss the legitimacy of this procedure. (author) 7 refs., 5 figs

  7. The effect of Al intermediate layer on thermal resistance of EB-PVD yttria-stabilized zirconia coatings on titanium substrate

    Science.gov (United States)

    Panin, Alexey; Panin, Victor; Kazachenok, Marina; Shugurov, Artur; Sinyakova, Elena; Martynov, Sergey; Rusyaev, Andrey; Kasterov, Artur

    2017-12-01

    The yttria-stabilized zirconia coatings sprayed on titanium substrates by the electron beam physical vapor deposition were subjected to thermal annealing in air at 1000°C for 1, 30 and 60 min. The delamination and fracture of the coatings are studied by the scanning electron microscopy and X-ray diffraction. It is shown that a magnetron sputtered Al interlayer between the coating and the substrate considerably improves the thermal resistance of ceramic coatings.

  8. Thermal stability of hexagonal OsB{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Zhilin [Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL 32816 (United States); Blair, Richard G. [Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL 32816 (United States); Department of Physics, University of Central Florida, Orlando, FL 32816 (United States); Orlovskaya, Nina, E-mail: Nina.Orlovskaya@ucf.edu [Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL 32816 (United States); Cullen, David A. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Andrew Payzant, E. [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2014-11-15

    The synthesis of novel hexagonal ReB{sub 2}-type OsB{sub 2} ceramic powder was performed by high energy ball milling of elemental Os and B powders. Two different sources of B powder have been used for this mechanochemical synthesis. One B powder consisted of a mixture of amorphous and crystalline phases and a mixture of {sup 10}B and {sup 11}B isotopes with a fine particle size, while another B powder was a purely crystalline (rhombohedral) material consisting of enriched {sup 11}B isotope with coarse particle size. The same Os powder was used for the synthesis in both cases. It was established that, in the first case, the hexagonal OsB{sub 2} phase was the main product of synthesis with a small quantity of Os{sub 2}B{sub 3} phase present after synthesis as an intermediate product. In the second case, where coarse crystalline {sup 11}B powder was used as a raw material, only Os{sub 2}B{sub 3} boride was synthesized mechanochemically. The thermal stability of hexagonal OsB{sub 2} powder was studied by heating under argon up to 876 °C and cooling in vacuo down to −225 °C. During the heating, the sacrificial reaction 2OsB{sub 2}+3O{sub 2}→2Os+2B{sub 2}O{sub 3} took place due to presence of O{sub 2}/water vapor molecules in the heating chamber, resulting in the oxidation of B atoms and formation of B{sub 2}O{sub 3} and precipitation of Os metal out of the OsB{sub 2} lattice. As a result of such phase changes during heating, the lattice parameters of hexagonal OsB{sub 2} changed significantly. The shrinkage of the a lattice parameter was recorded in 276–426 °C temperature range upon heating, which was attributed to the removal of B atoms from the OsB{sub 2} lattice due to oxidation followed by the precipitation of Os atoms and formation of Os metal. While significant structural changes occurred upon heating due to presence of O{sub 2}, the hexagonal OsB{sub 2} ceramic demonstrated good phase stability upon cooling in vacuo with linear shrinkage of the lattice

  9. Thermal stability of hexagonal OsB2

    International Nuclear Information System (INIS)

    Xie, Zhilin; Blair, Richard G.; Orlovskaya, Nina; Cullen, David A.; Andrew Payzant, E.

    2014-01-01

    The synthesis of novel hexagonal ReB 2 -type OsB 2 ceramic powder was performed by high energy ball milling of elemental Os and B powders. Two different sources of B powder have been used for this mechanochemical synthesis. One B powder consisted of a mixture of amorphous and crystalline phases and a mixture of 10 B and 11 B isotopes with a fine particle size, while another B powder was a purely crystalline (rhombohedral) material consisting of enriched 11 B isotope with coarse particle size. The same Os powder was used for the synthesis in both cases. It was established that, in the first case, the hexagonal OsB 2 phase was the main product of synthesis with a small quantity of Os 2 B 3 phase present after synthesis as an intermediate product. In the second case, where coarse crystalline 11 B powder was used as a raw material, only Os 2 B 3 boride was synthesized mechanochemically. The thermal stability of hexagonal OsB 2 powder was studied by heating under argon up to 876 °C and cooling in vacuo down to −225 °C. During the heating, the sacrificial reaction 2OsB 2 +3O 2 →2Os+2B 2 O 3 took place due to presence of O 2 /water vapor molecules in the heating chamber, resulting in the oxidation of B atoms and formation of B 2 O 3 and precipitation of Os metal out of the OsB 2 lattice. As a result of such phase changes during heating, the lattice parameters of hexagonal OsB 2 changed significantly. The shrinkage of the a lattice parameter was recorded in 276–426 °C temperature range upon heating, which was attributed to the removal of B atoms from the OsB 2 lattice due to oxidation followed by the precipitation of Os atoms and formation of Os metal. While significant structural changes occurred upon heating due to presence of O 2 , the hexagonal OsB 2 ceramic demonstrated good phase stability upon cooling in vacuo with linear shrinkage of the lattice parameters and no phase changes detected during cooling. - Graphical abstract: The in situ high temperature XRD

  10. First principles calculations of structural, electronic and thermal ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 37; Issue 5. First principles calculations of structural, electronic and thermal properties of lead chalcogenides PbS, PbSe and PbTe compounds. N Boukhris H Meradji S Amara Korba S Drablia S Ghemid F El Haj Hassan. Volume 37 Issue 5 August 2014 pp 1159-1166 ...

  11. The effect of the ergodic divertor on electron thermal confinement

    International Nuclear Information System (INIS)

    Harris, G.R.; Capes, H.; Garbet, X.

    1992-06-01

    The thermal confinement within the confinement zone of Tore Supra ohmically heated deuterium plasmas bounded by the ergodic divertor (ED) configuration is studied in a 1 1/2D analysis of the local power balance. Although the edge electron temperature and mean electron density (n e ) are both on average halved with application of the ED, the mean electron thermal diffusivity χ e shows the same density dependence as exhibited by standard ohmic limiter discharges, i.e., an Alcator-like inverse dependence on (n e ) at low density and a saturation at high density. The ion thermal transport at low to medium densities in both limiter and ED discharges is between 10 to 20 times that predicted by neoclassical theory. Comparing ED and limiter plasmas of the same density, a strong plasma decontamination is observed, with a reduction, in Z eff by between 1.0 to 1.5. The effective decoupling of (n e ) and Z eff by the ED and the invariant behaviour of χ e imply that electron thermal transport is only weakly dependent on Z eff in ohmic Tore Supra discharges

  12. First principles calculations of structural, electronic and thermal ...

    Indian Academy of Sciences (India)

    Administrator

    2013-07-28

    Jul 28, 2013 ... The structural, electronic and thermal properties of lead chalcogenides PbS, PbSe and BeTe using .... results for all the systems are presented in table 1, along ... as interatomic bonding, equations of state and phonon spectra.

  13. Thermal modeling and design of electronic systems and devices

    International Nuclear Information System (INIS)

    Wirtz, R.A.; Lehmann, G.L.

    1990-01-01

    The thermal control electronic devices, particularly those in complex systems with high heat flux density, continues to be of interest to engineers involved in system cooling design and analysis. This volume contains papers presented at the 1990 ASME Winter Annual Meeting in two K-16 sponsored sessions: Empirical Modeling of Heat Transfer in Complex Electronic Systems and Design and Modeling of Heat Transfer Devices in High-Density Electronics. The first group deals with understanding the heat transfer processes in these complex systems. The second group focuses on the use of analysis techniques and empirically determined data in predicting device and system operating performance

  14. Stabilization of electron beam spot size by self bias potential

    International Nuclear Information System (INIS)

    Kwan, T.J.T.; Moir, D.C.; Snell, C.M.; Kang, M.

    1998-01-01

    In high resolution flash x-ray imaging technology the electric field developed between the electron beam and the converter target is large enough to draw ions from the target surface. The ions provide fractional neutralization and cause the electron beam to focus radially inward, and the focal point subsequently moves upstream due to the expansion of the ion column. A self-bias target concept is proposed and verified via computer simulation that the electron charge deposited on the target can generate an electric potential, which can effectively limit the ion motion and thereby stabilize the growth of the spot size. A target chamber using the self bias target concept was designed and tested in the Integrated Test Stand (ITS). The authors have obtained good agreement between computer simulation and experiment

  15. Thermal stability of hexagonal OsB2

    Science.gov (United States)

    Xie, Zhilin; Blair, Richard G.; Orlovskaya, Nina; Cullen, David A.; Andrew Payzant, E.

    2014-11-01

    The synthesis of novel hexagonal ReB2-type OsB2 ceramic powder was performed by high energy ball milling of elemental Os and B powders. Two different sources of B powder have been used for this mechanochemical synthesis. One B powder consisted of a mixture of amorphous and crystalline phases and a mixture of 10B and 11B isotopes with a fine particle size, while another B powder was a purely crystalline (rhombohedral) material consisting of enriched 11B isotope with coarse particle size. The same Os powder was used for the synthesis in both cases. It was established that, in the first case, the hexagonal OsB2 phase was the main product of synthesis with a small quantity of Os2B3 phase present after synthesis as an intermediate product. In the second case, where coarse crystalline 11B powder was used as a raw material, only Os2B3 boride was synthesized mechanochemically. The thermal stability of hexagonal OsB2 powder was studied by heating under argon up to 876 °C and cooling in vacuo down to -225 °C. During the heating, the sacrificial reaction 2OsB2+3O2→2Os+2B2O3 took place due to presence of O2/water vapor molecules in the heating chamber, resulting in the oxidation of B atoms and formation of B2O3 and precipitation of Os metal out of the OsB2 lattice. As a result of such phase changes during heating, the lattice parameters of hexagonal OsB2 changed significantly. The shrinkage of the a lattice parameter was recorded in 276-426 °C temperature range upon heating, which was attributed to the removal of B atoms from the OsB2 lattice due to oxidation followed by the precipitation of Os atoms and formation of Os metal. While significant structural changes occurred upon heating due to presence of O2, the hexagonal OsB2 ceramic demonstrated good phase stability upon cooling in vacuo with linear shrinkage of the lattice parameters and no phase changes detected during cooling.

  16. Stability of trapped electrons in SiO2

    International Nuclear Information System (INIS)

    Fleetwood, D.M.; Winokur, P.S.; Flament, O.; Leray, J.L.

    1998-01-01

    Electron trapping near the Si/SiO 2 interface plays a crucial role in mitigating the response of MOS devices to ionizing radiation or high-field stress. These electrons offset positive charge due to trapped holes, and can be present at densities exceeding 10 12 cm -2 in the presence of a similar density of trapped positive charge. The nature of the defects that serve as hosts for trapped electrons in the near-interfacial SiO 2 is presently unknown, although there is compelling evidence that these defects are often intimately associated with trapped holes. This association is depicted most directly in the model of Lelis et al., which suggests that trapped electrons and holes occupy opposite sides of a compensated E center in SiO 2 . Charge exchange between electron traps and the Si can occur over a wide range of time scales, depending on the trap depth and location relative to the Si/SiO 2 interface. Here the authors report a detailed study of the stability of electron traps associated with trapped holes near the Si/SiO 2 interface

  17. Thermal Stability of Silver Paste Sintering on Coated Copper and Aluminum Substrates

    Science.gov (United States)

    Pei, Chun; Chen, Chuantong; Suganuma, Katsuaki; Fu, Guicui

    2018-01-01

    The thermal stability of silver (Ag) paste sintering on coated copper (Cu) and aluminum (Al) substrates has been investigated. Instead of conventional zincating or nickel plating, magnetron sputtering was used to achieve coating with titanium (Ti) and Ag. Silicon (Si) chips were bonded to coated Cu and Al substrates using a mixture of submicron Ag flakes and particles under 250°C and 0.4 MPa for 30 min. The joints were then subject to aging testing at 250°C for duration of 200 h, 500 h, and 1000 h. Two types of joints exhibited satisfactory initial shear strength above 45 MPa. However, the shear strength of the joints on Al substrate decreased to 28 MPa after 1000 h of aging, while no shear strength decline was detected for the joints on Cu substrate. Fracture surface analysis revealed that the vulnerable points of the two types of joints were (1) the Ag layer and (2) the interface between the Ti layer and Cu substrate. Based on the results of scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), and simulations, cracks in the Ag layer were identified as the cause of the shear strength degradation in the joints on Al substrate. The interface evolution of the joints on Cu substrate was ascribed to Cu migration and discontinuity points that initialized in the Ti layer. This study reveals that Al exhibited superior thermal stability with sintered Ag paste.

  18. Thermal stability and phase transformations of martensitic Ti–Nb alloys

    Directory of Open Access Journals (Sweden)

    Matthias Bönisch, Mariana Calin, Thomas Waitz, Ajit Panigrahi, Michael Zehetbauer, Annett Gebert, Werner Skrotzki and Jürgen Eckert

    2013-01-01

    Full Text Available Aiming at understanding the governing microstructural phenomena during heat treatments of Ni-free Ti-based shape memory materials for biomedical applications, a series of Ti–Nb alloys with Nb concentrations up to 29 wt% was produced by cold-crucible casting, followed by homogenization treatment and water quenching. Despite the large amount of literature available concerning the thermal stability and ageing behavior of Ti–Nb alloys, only few studies were performed dealing with the isochronal transformation behavior of initially martensitic Ti–Nb alloys. In this work, the formation of martensites (α' and α'' and their stability under different thermal processing conditions were investigated by a combination of x-ray diffraction, differential scanning calorimetry, dilatometry and electron microscopy. The effect of Nb additions on the structural competition in correlation with stable and metastable phase diagrams was also studied. Alloys with 24 wt% Nb or less undergo a transformation sequence on heating from room temperature to 1155 K. In alloys containing >24 wt% Nb α'' martensitically reverts back to β0, which is highly unstable against chemical demixing by formation of isothermal ωiso. During slow cooling from the single phase β domain α precipitates and only very limited amounts of α'' martensite form.

  19. Correlation between Thermal Treatment and Phase Transformation in Nanocrystalline Stabilized Zirconia

    Directory of Open Access Journals (Sweden)

    Tajudeen Oladele AHMED

    2013-06-01

    Full Text Available Stabilized zirconia produced via wet chemistry has chemically higher uniformity and purity. However, the grain size, particle shape, agglomerate size and specific surface area can be modified within certain degree by controlling the precipitation and sintering conditions. Generally, any physical or chemical difference between phases or effect occurring on the appearance or disappearance of a phase can be determined via thermal analysis and X-ray Diffractometry coupled with electron microscopy. In the last few decades, these materials have received tremendous attention globally in the field of defect solid-state devices. However, the challenge in this field of research has been to study thermal behaviour of these electrolytes during phase transformations and develop improved electrolytes with low activation temperature in the range of 600°C-800°C. In this paper, we report the wet chemistry of bismuth oxide stabilized zirconia having high experimental yield and low transformation temperature. Thus, the phase transformation from amorphous Zirconia to monoclinic is reported to begin above 600oC to an optimum temperature of 700oC. After calcination at 800oC for 4h, the powder have narrow particle size distribution in the range of 63-101µm. The average crystallite sizes of the synthesized powders range from 8-33nm.

  20. Thermal Stability of Copper-Aluminum Alloy Thin Films for Barrierless Copper Metallization on Silicon Substrate

    Science.gov (United States)

    Wang, C. P.; Dai, T.; Lu, Y.; Shi, Z.; Ruan, J. J.; Guo, Y. H.; Liu, X. J.

    2017-08-01

    Copper thin films with thickness of about 500 nm doped with different aluminum concentrations have been prepared by magnetron sputtering on Si substrate and their crystal structure, microstructure, and electrical resistivity after annealing at various temperatures (200°C to 600°C) for 1 h or at 400°C for different durations (1 h to 11 h) investigated by grazing-incidence x-ray diffraction (GIXRD) analysis, scanning electron microscopy (SEM), and four-point probe (FPP) measurements. Cu-1.8Al alloy thin film exhibited good thermal stability and low electrical resistivity (˜5.0 μΩ cm) after annealing at 500°C for 1 h or 400°C for 7 h. No copper silicide was observed at the Cu-Al/Si interface by GIXRD analysis or SEM for this sample. This result indicates that doping Cu thin film with small amounts of Al can achieve high thermal stability and low electrical resistivity, suggesting that Cu-1.8Al alloy thin film could be used for barrierless Cu metallization on Si substrate.

  1. Mechanical synthesis of copper-carbon nanocomposites: Structural changes, strengthening and thermal stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Nunes, D., E-mail: daniela.nunes@ist.utl.pt [Associacao Euratom/IST, Instituto de Plasmas e Fusao Nuclear - Laboratorio Associado, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); LNEG, Estrada do Paco do Lumiar, 1649-038 Lisboa (Portugal); ICEMS, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Livramento, V. [Associacao Euratom/IST, Instituto de Plasmas e Fusao Nuclear - Laboratorio Associado, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); LNEG, Estrada do Paco do Lumiar, 1649-038 Lisboa (Portugal); Mateus, R. [Associacao Euratom/IST, Instituto de Plasmas e Fusao Nuclear - Laboratorio Associado, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Correia, J.B. [LNEG, Estrada do Paco do Lumiar, 1649-038 Lisboa (Portugal); Alves, L.C. [ITN, Instituto Tecnologico e Nuclear, Estrada Nacional 10, 2686-953 Sacavem (Portugal); Vilarigues, M. [Departamento de Conservacao e Restauro e R and D Unit Vidro e da Ceramica Para as Artes, FCT-UNL, Quinta da Torre, 2829-516 Caparica (Portugal); Carvalho, P.A. [ICEMS, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Departamento de Bioengenharia, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal)

    2011-11-15

    Highlights: {yields} The study characterized Cu-nanodiamond (Cu-nD) and Cu-graphite (Cu-G) composites. {yields} Preservation of nD crystalline structure during high-energy milling was demonstrated. {yields} Higher refinement of matrix in Cu-nD comparing to Cu-G is due to a milling mechanism. {yields} Remarkable thermal stability and microhardness have been achieved in Cu-nD and Cu-G. {yields} Strengthening resulted mainly from grain refinement and second-phase reinforcement. - Abstract: Processing of copper-carbon nanocomposites by mechanical synthesis poses specific challenges as carbon phases are prone to amorphization and exhibit an intrinsically difficult bonding with copper. The present work investigates Cu-nanodiamond (Cu-nD) and Cu-graphite (Cu-G) composites produced by mechanical synthesis and subsequent heat treatments. Transmission electron microscopy observations showed homogeneous particle distributions and intimate bonding between the metallic matrix and the carbon phases. Ring diffraction patterns of chemically extracted carbon phases demonstrated that milled nanodiamond preserved crystallinity, while an essentially amorphous nature could be inferred for milled graphite. Raman spectra confirmed that nanodiamond particles remained essentially unaffected by the mechanical synthesis, whereas the bands of milled graphite were significantly changed into the typical amorphous carbon fingerprint. Particle-induced X-ray emission spectroscopy showed that the total contamination originating from the milling media remained below 0.7 wt.%. The Cu-nanodiamond composite exhibited remarkable microhardness and microstructural thermal stability when compared with pure nanostructured copper.

  2. Effects of fluoride residue on thermal stability in Cu/porous low-k interconnects

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Y.; Ozaki, S.; Nakamura, T. [FUJITSU LABORATORIES Ltd., 10-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0197 (Japan)

    2014-06-19

    We have investigated the effects of fluoride residue on the thermal stability of a Cu/barrier metal (BM)/porous low-k film (k < 2.3) structure. We confirmed that the Cu agglomerated more on a BM/inter layer dielectric (ILD) with a fluoride residue. To consider the effect of fluoride residue on Cu agglomeration, the structural state at the Cu/BM interface was evaluated with a cross-section transmission electron microscope (TEM) and atomic force microscope (AFM). In addition, the chemical bonding state at the Cu/BM interface was evaluated with the interface peeling-off method and X-ray photoelectron spectroscopy (XPS). Moreover, we confirmed the ionization of fluoride residue and oxidation of Cu with fluoride and moisture to clarify the effect of fluoride residue on Cu. Our experimental results indicated that the thermal stability in Cu/porous low-k interconnects was degraded by enhancement of Cu oxidation with fluoride ions diffusion as an oxidizing catalyst.

  3. Mechanical synthesis of copper-carbon nanocomposites: Structural changes, strengthening and thermal stabilization

    International Nuclear Information System (INIS)

    Nunes, D.; Livramento, V.; Mateus, R.; Correia, J.B.; Alves, L.C.; Vilarigues, M.; Carvalho, P.A.

    2011-01-01

    Highlights: → The study characterized Cu-nanodiamond (Cu-nD) and Cu-graphite (Cu-G) composites. → Preservation of nD crystalline structure during high-energy milling was demonstrated. → Higher refinement of matrix in Cu-nD comparing to Cu-G is due to a milling mechanism. → Remarkable thermal stability and microhardness have been achieved in Cu-nD and Cu-G. → Strengthening resulted mainly from grain refinement and second-phase reinforcement. - Abstract: Processing of copper-carbon nanocomposites by mechanical synthesis poses specific challenges as carbon phases are prone to amorphization and exhibit an intrinsically difficult bonding with copper. The present work investigates Cu-nanodiamond (Cu-nD) and Cu-graphite (Cu-G) composites produced by mechanical synthesis and subsequent heat treatments. Transmission electron microscopy observations showed homogeneous particle distributions and intimate bonding between the metallic matrix and the carbon phases. Ring diffraction patterns of chemically extracted carbon phases demonstrated that milled nanodiamond preserved crystallinity, while an essentially amorphous nature could be inferred for milled graphite. Raman spectra confirmed that nanodiamond particles remained essentially unaffected by the mechanical synthesis, whereas the bands of milled graphite were significantly changed into the typical amorphous carbon fingerprint. Particle-induced X-ray emission spectroscopy showed that the total contamination originating from the milling media remained below 0.7 wt.%. The Cu-nanodiamond composite exhibited remarkable microhardness and microstructural thermal stability when compared with pure nanostructured copper.

  4. Oblique propagation of electron thermal modes below the electron plasma frequency without boundary effects

    International Nuclear Information System (INIS)

    Ohnuma, T.; Watanabe, T.; Sanuki, H.

    1981-08-01

    Propagation characteristics and refractive effects of an oblique electron thermal mode without boundary effects below the electron plasma frequency are studied experimentally and theoretically in an inhomogeneous magnetized plasma. The behavior of this mode observed experimentally was confirmed by the theoretical analysis based on a new type of ray theory. (author)

  5. Thermochemical stability of zirconia-titanium nitride as mixed ionic-electronic composites

    DEFF Research Database (Denmark)

    Silva, P. S. M.; Esposito, V.; Marani, D.

    2018-01-01

    Dense zirconia (8% molar yttria-stabilized ZrO2)-titanium nitride (TiN) composites are fabricated to obtain mixed ionic-electronic conducting ceramic systems with high degree of electronic and thermal conductivity. The composites are consolidated by spark plasma sintering (SPS), starting from pure...... the composites, high electrical conductivity is attained. Samples exhibit metallic behavior, showing an unexpected percolation of TiN in the YSZ matrix for volume fraction ≤ 25 wt% (27 vol%). Chemical degradation and electrical properties of the compounds were monitored under oxidative (air) and inert (Ar...... transport properties of the composite can be tuned by both the relative volume fraction of phases and controlled oxidative treatments. Adjusting such parameters different electric behaviors were observed ranging from predominant electronic conductors, to temperature-independent resistivity...

  6. Thermal phase stability of some simulated Defense waste glasses

    International Nuclear Information System (INIS)

    May, R.P.

    1981-04-01

    Three simulated defense waste glass compositions developed by Savannah River Laboratories were studied to determine viscosity and compositional effects on the comparative thermal phase stabilities of these glasses. The glass compositions are similar except that the 411 glasses are high in lithium and low in sodium compared to the 211 glass, and the T glasses are high in iron and low in aluminum compared to the C glass. Specimens of these glasses were heat treated using isothermal anneals as short as 10 min and up to 15 days over the temperature range of 450 0 C to 1100 0 C. Additionally, a specimen of each glass was cooled at a constant cooling rate of 7 0 C/hour from an 1100 0 C melt down to 500 0 C where it was removed from the furnace. The following were observed. The slow cooling rate of 7 0 C/hour is possible as a canister centerline cooling rate for large canisters. Accordingly, it is important to note that a short range diffusion mechanism like cooperative growth phenomena can result in extensive devitrification at lower temperatures and higher yields than a long-range diffusion mechanism can; and can do it without the growth of large crystals that can fracture the glass. Refractory oxides like CeO 2 and (Ni, Mn, Fe) 2 O 4 form very rapidly at higher temperatures than silicates and significant yields can be obtained at sufficiently high temperatures that settling of these dense phases becomes a major microstructural feature during slow cooling of some glasses. These annealing studies further show that below 500 0 C there is but little devitrification occurring implying that glass canisters stored at 300 0 C may be kinetically stable despite not being thermodynamically so

  7. Thermal phase stability of some simulated Defense waste glasses

    Energy Technology Data Exchange (ETDEWEB)

    May, R.P.

    1981-04-01

    Three simulated defense waste glass compositions developed by Savannah River Laboratories were studied to determine viscosity and compositional effects on the comparative thermal phase stabilities of these glasses. The glass compositions are similar except that the 411 glasses are high in lithium and low in sodium compared to the 211 glass, and the T glasses are high in iron and low in aluminum compared to the C glass. Specimens of these glasses were heat treated using isothermal anneals as short as 10 min and up to 15 days over the temperature range of 450/sup 0/C to 1100/sup 0/C. Additionally, a specimen of each glass was cooled at a constant cooling rate of 7/sup 0/C/hour from an 1100/sup 0/C melt down to 500/sup 0/C where it was removed from the furnace. The following were observed. The slow cooling rate of 7/sup 0/C/hour is possible as a canister centerline cooling rate for large canisters. Accordingly, it is important to note that a short range diffusion mechanism like cooperative growth phenomena can result in extensive devitrification at lower temperatures and higher yields than a long-range diffusion mechanism can; and can do it without the growth of large crystals that can fracture the glass. Refractory oxides like CeO/sub 2/ and (Ni, Mn, Fe)/sub 2/O/sub 4/ form very rapidly at higher temperatures than silicates and significant yields can be obtained at sufficiently high temperatures that settling of these dense phases becomes a major microstructural feature during slow cooling of some glasses. These annealing studies further show that below 500/sup 0/C there is but little devitrification occurring implying that glass canisters stored at 300/sup 0/C may be kinetically stable despite not being thermodynamically so.

  8. Color center annealing and ageing in electron and ion-irradiated yttria-stabilized zirconia

    International Nuclear Information System (INIS)

    Costantini, Jean-Marc; Beuneu, Francois

    2005-01-01

    We have used X-band electron paramagnetic resonance (EPR) measurements at room-temperature (RT) to study the thermal annealing and RT ageing of color centers induced in yttria-stabilized zirconia (YSZ), i.e. ZrO 2 :Y with 9.5 mol% Y 2 O 3 , by swift electron and ion-irradiations. YSZ single crystals with the orientation were irradiated with 2.5 MeV electrons, and implanted with 100 MeV 13 C ions. Electron and ion beams produce the same two color centers, namely an F + -type center (singly ionized oxygen vacancy) and the so-called T-center (Zr 3+ in a trigonal oxygen local environment) which is also produced by X-ray irradiations. Isochronal annealing was performed in air up to 973 K. For both electron and ion irradiations, the defect densities are plotted versus temperature or time at various fluences. The influence of a thermal treatment at 1373 K of the YSZ single crystals under vacuum prior to the irradiations was also investigated. In these reduced samples, color centers are found to be more stable than in as-received samples. Two kinds of recovery processes are observed depending on fluence and heat treatment

  9. On the impact of atmospheric thermal stability on the characteristics of nocturnal downslope flows

    Science.gov (United States)

    Ye, Z. J.; Garratt, J. R.; Segal, M.; Pielke, R. A.

    1990-04-01

    The impacts of background (or ambient) and local atmospheric thermal stabilities, and slope steepness, on nighttime thermally induced downslope flow in meso-β domains (i.e., 20 200 km horizontal extent) have been investigated using analytical and numerical model approaches. Good agreement between the analytical and numerical evaluations was found. It was concluded that: (i) as anticipated, the intensity of the downslope flow increases with increased slope steepness, although the depth of the downslope flow was found to be insensitive to slope steepness in the studied situations; (ii) the intensity of the downslope flow is generally independent of background atmospheric thermal stability; (iii) for given integrated nighttime cooling across the nocturnal boundary layer (NBL), Q s the local atmospheric thermal stability exerts a strong influence on downslope flow behavior: the downslope flow intensity increases when local atmospheric thermal stability increases; and (iv) the downslope flow intensity is proportional to Q s 1/2.

  10. Pulsational stabilities of a star in thermal imbalance: comparison between the methods

    International Nuclear Information System (INIS)

    Vemury, S.K.

    1978-01-01

    The stability coefficients for quasi-adiabatic pulsations for a model in thermal imbalance are evaluated using the dynamical energy (DE) approach, the total (kinetic plus potential) energy (TE) approach, and the small amplitude (SA) approaches. From a comparison among the methods, it is found that there can exist two distinct stability coefficients under conditions of thermal imbalance as pointed out by Demaret. It is shown that both the TE approaches lead to one stability coefficient, while both the SA approaches lead to another coefficient. The coefficient obtained through the energy approaches is identified as the one which determines the stability of the velocity amplitudes.For a prenova model with a thin hydrogen-burning shell in thermal imbalance, several radial modes are found to be unstable both for radial displacements and for velocity amplitudes. However, a new kind of pulsational instability also appears, viz., while the radial displacements are unstable, the velocity amplitudes may be stabilized through the thermal imbalance terms

  11. Thermal stability, swelling behavior and CO 2 absorption properties of Nanoscale Ionic Materials (NIMs)

    KAUST Repository

    Andrew Lin, Kun-Yi; Park, Youngjune; Petit, Camille; Park, Ah-Hyung Alissa

    2014-01-01

    © The Royal Society of Chemistry 2015. Nanoscale Ionic Materials (NIMs) consist of a nanoscale core, a corona of charged brushes tethered on the surface of the core, and a canopy of the oppositely charged species linked to the corona. Unlike conventional polymeric nanocomposites, NIMs can display liquid-like behavior in the absence of solvents, have a negligible vapor pressure and exhibit unique solvation properties. These features enable NIMs to be a promising CO2 capture material. To optimize NIMs for CO2 capture, their structure-property relationships were examined by investigating the roles of the canopy and the core in their thermal stability, and thermally- and CO2-induced swelling behaviors. NIMs with different canopy sizes and core fractions were synthesized and their thermal stability as well as thermally- and CO2-induced swelling behaviors were determined using thermogravimetry, and ATR FT-IR and Raman spectroscopies. It was found that the ionic bonds between the canopy and the corona, as well as covalent bonds between the corona and the core significantly improved the thermal stability compared to pure polymer and polymer/nanofiller mixtures. A smaller canopy size and a larger core fraction led to a greater enhancement in thermal stability. This thermal stability enhancement was responsible for the long-term thermal stability of NIMs over 100 temperature swing cycles. Owing to their ordered structure, NIMs swelled less when heated or when they adsorbed CO2 compared to their corresponding polymers. This journal is

  12. Thermal stability, swelling behavior and CO 2 absorption properties of Nanoscale Ionic Materials (NIMs)

    KAUST Repository

    Andrew Lin, Kun-Yi

    2014-11-11

    © The Royal Society of Chemistry 2015. Nanoscale Ionic Materials (NIMs) consist of a nanoscale core, a corona of charged brushes tethered on the surface of the core, and a canopy of the oppositely charged species linked to the corona. Unlike conventional polymeric nanocomposites, NIMs can display liquid-like behavior in the absence of solvents, have a negligible vapor pressure and exhibit unique solvation properties. These features enable NIMs to be a promising CO2 capture material. To optimize NIMs for CO2 capture, their structure-property relationships were examined by investigating the roles of the canopy and the core in their thermal stability, and thermally- and CO2-induced swelling behaviors. NIMs with different canopy sizes and core fractions were synthesized and their thermal stability as well as thermally- and CO2-induced swelling behaviors were determined using thermogravimetry, and ATR FT-IR and Raman spectroscopies. It was found that the ionic bonds between the canopy and the corona, as well as covalent bonds between the corona and the core significantly improved the thermal stability compared to pure polymer and polymer/nanofiller mixtures. A smaller canopy size and a larger core fraction led to a greater enhancement in thermal stability. This thermal stability enhancement was responsible for the long-term thermal stability of NIMs over 100 temperature swing cycles. Owing to their ordered structure, NIMs swelled less when heated or when they adsorbed CO2 compared to their corresponding polymers. This journal is

  13. Electrically and Thermally Conducting Nanocomposites for Electronic Applications

    Directory of Open Access Journals (Sweden)

    Daryl Santos

    2010-02-01

    Full Text Available Nanocomposites made up of polymer matrices and carbon nanotubes are a class of advanced materials with great application potential in electronics packaging. Nanocomposites with carbon nanotubes as fillers have been designed with the aim of exploiting the high thermal, electrical and mechanical properties characteristic of carbon nanotubes. Heat dissipation in electronic devices requires interface materials with high thermal conductivity. Here, current developments and challenges in the application of nanotubes as fillers in polymer matrices are explored. The blending together of nanotubes and polymers result in what are known as nanocomposites. Among the most pressing current issues related to nanocomposite fabrication are (i dispersion of carbon nanotubes in the polymer host, (ii carbon nanotube-polymer interaction and the nature of the interface, and (iii alignment of carbon nanotubes in a polymer matrix. These issues are believed to be directly related to the electrical and thermal performance of nanocomposites. The recent progress in the fabrication of nanocomposites with carbon nanotubes as fillers and their potential application in electronics packaging as thermal interface materials is also reported.

  14. Phase change Materials (PCM) microcapsules with different shell compositions: Preparation, characterization and thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Bayes-Garcia, L.; Ventola, L.; Cordobilla, R.; Benages, R.; Calvet, T.; Cuevas-Diarte, M.A. [Departament de Cristal.lografia, Mineralogia i Diposits Minerals, Facultat de Geologia, Universitat de Barcelona, Marti i Franques s/n, E-08028 Barcelona (Spain)

    2010-07-15

    In this study, phase change materials (Rubitherm registered RT 27) microcapsules were successfully obtained by two different methods. The main difference between them remains on the shell composition, as they are composed of different coacervates (Sterilized Gelatine/Arabic Gum for the SG/AG method and Agar-Agar/Arabic Gum for the AA/AG method). Microcapsules were thermally characterized by thermo-optical microscopy and differential scanning calorimetry. Using scanning electron microscopy, their spherical morphology (sphericity factor of 0.94-0.95) and their particle size distribution were determined, obtaining an average diameter of 12 {mu}m for the SG/AG method and lower values for the AA/AG method, where nanocapsules were also observed (average diameter of 4.3 {mu}m for the microcapsules and 104 nm for the nanocapsules). The thermal stability determination was carried out by Thermogravimetric analyses (TG) and the results show a high decomposition temperature, although the process takes places in four steps for the two mentioned methods. Moreover, the microcapsules obtained by the AA/AG method decompose in a more gradual way, as in the TG results a double step, instead of one, is appreciable. On the whole, the prepared microencapsulated PCM are totally capable of developing their role in thermal energy storage. (author)

  15. Enhancement of thermal stability of multiwalled carbon nanotubes via different silanization routes

    International Nuclear Information System (INIS)

    Scheibe, B.; Borowiak-Palen, E.; Kalenczuk, R.J.

    2010-01-01

    This work presents an effect of two different silanization procedures on thermal and structural properties of oxidized and oxidized followed by sodium borohydrate (NaBH 4 ) reduction of multiwalled carbon nanotubes (MWCNTs). Purified sample was oxidized in a mixture of nitric and sulfuric acids in a reflux. An oxidized material was divided into two batches. The first batch underwent a silanization procedure directly, while the second batch was reduced by NaBH 4 treatment prior to the silanization. The silanization experiments were performed: (A) with γ-aminopropyltriethoxysilane (APTES) at room temperature in acetone (pH ∼7) and (B) with condensated γ-aminopropyltriethoxysilane at 40 o C in water (pH 4). The extent of the functionalization of the samples after each procedure was examined by Raman spectroscopy. The vibrational properties of the materials were studied via Fourier transform infrared spectroscopy. Boehms titration technique was applied to quantify the amount of the functional groups on MWCNTs. The morphology of the pristine and functionalized carbon nanotubes was exposed to high-resolution transmission electron microscopy analysis. The energy dispersive X-ray (EDX) analysis was used to characterize the elemental composition of each sample. The effect of the silanization process on the thermal properties of MWCNTs was investigated by thermogravimetry analysis. Interestingly, the significant increase of the thermal stability of silanized MWCNTs samples in respect to the pristine MWCNTs was observed.

  16. Stability of the antiferromagnetic state in the electron doped iridates

    Science.gov (United States)

    Bhowal, Sayantika; Moradi Kurdestany, Jamshid; Satpathy, Sashi

    2018-06-01

    Iridates such as Sr2IrO4 are of considerable interest owing to the formation of the Mott insulating state driven by a large spin–orbit coupling. However, in contrast to the expectation from the Nagaoka theorem that a single doped hole or electron destroys the anti-ferromagnetic (AFM) state of the half-filled Hubbard model in the large U limit, the anti-ferromagnetism persists in the doped Iridates for a large dopant concentration beyond half-filling. With a tight-binding description of the relevant states by the third-neighbor (t 1, t 2, t 3, U) Hubbard model on the square lattice, we examine the stability of the AFM state to the formation of a spin spiral state in the strong coupling limit. The third-neighbor interaction t 3 is important for the description of the Fermi surface of the electron doped system. A phase diagram in the parameter space is obtained for the regions of stability of the AFM state. Our results qualitatively explain the robustness of the AFM state in the electron doped iridate (such as Sr2‑x La x IrO4), observed in many experiments, where the AFM state continues to be stable until a critical dopant concentration.

  17. On the stability and the genesis of the electron

    International Nuclear Information System (INIS)

    Yadava, K.S.

    1976-01-01

    The present paper intends to develop a self-consistent field theory of the electron, purely within the realm of classical electrodynamics, which accounts for its existence, its finite size, its charge distribution and its stability. It is shown that an electron can be interpreted as a small region of the field (of the order of 10 - 15m) in which the field values are extremely great. These small regions of the field which would correspond to our usual notion of particles are known as bunched fields. Such bunched fields have been constructed here by finding a discrete number of solutions for Poisson's equation in electrostatics, which are everywhere singularity free, static and spherically symmetric in the domain 0 approximately equal to γ approximately infinity. The corresponding electric fields are also regular everywhere. Both the charge and the mass of the particle are then completely expressed in terms of these regular fields. The theory developed accounts for the existence of the electron, its finite size, its charge distribution and its stability

  18. Simulation of electron thermal transport in H-mode discharges

    International Nuclear Information System (INIS)

    Rafiq, T.; Pankin, A. Y.; Bateman, G.; Kritz, A. H.; Halpern, F. D.

    2009-01-01

    Electron thermal transport in DIII-D H-mode tokamak plasmas [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] is investigated by comparing predictive simulation results for the evolution of electron temperature profiles with experimental data. The comparison includes the entire profile from the magnetic axis to the bottom of the pedestal. In the simulations, carried out using the automated system for transport analysis (ASTRA) integrated modeling code, different combinations of electron thermal transport models are considered. The combinations include models for electron temperature gradient (ETG) anomalous transport and trapped electron mode (TEM) anomalous transport, as well as a model for paleoclassical transport [J. D. Callen, Nucl. Fusion 45, 1120 (2005)]. It is found that the electromagnetic limit of the Horton ETG model [W. Horton et al., Phys. Fluids 31, 2971 (1988)] provides an important contribution near the magnetic axis, which is a region where the ETG mode in the GLF23 model [R. E. Waltz et al., Phys. Plasmas 4, 2482 (1997)] is below threshold. In simulations of DIII-D discharges, the observed shape of the H-mode edge pedestal is produced when transport associated with the TEM component of the GLF23 model is suppressed and transport given by the paleoclassical model is included. In a study involving 15 DIII-D H-mode discharges, it is found that with a particular combination of electron thermal transport models, the average rms deviation of the predicted electron temperature profile from the experimental profile is reduced to 9% and the offset to -4%.

  19. Significance of fundamental processes of radiation chemistry in hot atom chemical processes: electron thermalization

    International Nuclear Information System (INIS)

    Nishikawa, M.

    1984-01-01

    The author briefly reviews the current understanding of the course of electron thermalization. An outline is given of the physical picture without going into mathematical details. The analogy of electron thermalization with hot atom processes is taken as guiding principle in this paper. Content: secondary electrons (generation, track structure, yields); thermalization (mechanism, time, spatial distribution); behaviour of hot electrons. (Auth.)

  20. Uranyl soaps - thermal, electronic and infrared spectral study

    International Nuclear Information System (INIS)

    Solanki, A.K.; Bhandari, A.M.

    1981-01-01

    The electronic and infrared spectra and TGA thermogram of uranyl soaps (laurate, mystrate, palmitate and stearate) have been studied. The environment about the UO 2+ 2 ion would comprise two 'short bite' bidentate carboxylate groups and oxygen atoms bridging from adjacent carboxylic molecules. The uranyl soaps have UO 2+ 2 vibronic absorption (approx. equal to 22730 cm -1 ) in the range found for eight coordinate uranyl complexes. The greater resistance to thermal degradation (approx. equal to 300 0 C) of these soaps and their stepwise thermal degradation infer strong metal-ligand interaction. (orig.) [de

  1. On thermalization of electron-positron-photon plasma

    Energy Technology Data Exchange (ETDEWEB)

    Siutsou, I. A., E-mail: siutsou@icranet.org [CAPES–ICRANet program, ICRANet–Rio, CBPF 22290-180, Rua Dr. Xavier Sigaud, 150, Urca, Rio de Janeiro, RJ (Brazil); Aksenov, A. G. [Institute for Computer-Aided Design, Russian Academy of Sciences 123056, 2nd Brestskaya st., 19/18, Moscow (Russian Federation); Vereshchagin, G. V. [ICRANet 65122, p.le della Republica, 10, Pescara (Italy)

    2015-12-17

    Recently a progress has been made in understanding thermalization mechanism of relativistic plasma starting from a non-equilibrium state. Relativistic Boltzmann equations were solved numerically for homogeneous isotropic plasma with collision integrals for two- and three-particle interactions calculated from the first principles by means of QED matrix elements. All particles were assumed to fulfill Boltzmann statistics. In this work we follow plasma thermalization by accounting for Bose enhancement and Pauli blocking in particle interactions. Our results show that particle in equilibrium reach Bose-Einstein distribution for photons, and Fermi-Dirac one for electrons, respectively.

  2. On thermalization of electron-positron-photon plasma

    Science.gov (United States)

    Siutsou, I. A.; Aksenov, A. G.; Vereshchagin, G. V.

    2015-12-01

    Recently a progress has been made in understanding thermalization mechanism of relativistic plasma starting from a non-equilibrium state. Relativistic Boltzmann equations were solved numerically for homogeneous isotropic plasma with collision integrals for two- and three-particle interactions calculated from the first principles by means of QED matrix elements. All particles were assumed to fulfill Boltzmann statistics. In this work we follow plasma thermalization by accounting for Bose enhancement and Pauli blocking in particle interactions. Our results show that particle in equilibrium reach Bose-Einstein distribution for photons, and Fermi-Dirac one for electrons, respectively.

  3. 76 FR 49532 - Federal Motor Vehicle Safety Standards; Electronic Stability Control; Technical Report on the...

    Science.gov (United States)

    2011-08-10

    ...-0112] Federal Motor Vehicle Safety Standards; Electronic Stability Control; Technical Report on the Effectiveness of Electronic Stability Control Systems for Cars and LTVs AGENCY: National Highway Traffic Safety..., Electronic Stability Control Systems. The report's title is: Crash Prevention Effectiveness in Light-Vehicle...

  4. An Optimized Thermal Analysis of Electronic Unit Used in Aircraft

    International Nuclear Information System (INIS)

    Shah, A.N.; Mir, F.; Farooq, M.; Farooq, M.

    2014-01-01

    In a field where change and growth is inevitable, new electronic packaging problems continuously arise. Smaller, but more powerful devices are prone to overheating causing intermittent system failures, corrupted signals and outright system failure. Current study is focused on the analysis of the optimized working of electronic equipment from thermal point of view. In order to achieve the objective, an approach was developed for the thermal analysis of Printed Circuit Board (PCB) including the heat dissipation of its electronic components and then removal of the heat in a sophisticated manner by considering the conduction and convection modes of heat transfer. Mathematical modeling was carried out for a certain problem to address the thermal design, and then a program was developed in MATLAB for the solution of model by using Newton-Raphson method. The proposed unit is to be mounted on an aircraft having suspected thermal characteristics owing to abrupt changes in pressure and temperature as aircraft moves quickly from a lower altitude to higher altitude. In current study, dominant mode of heat transfer was conduction revealing that the major portion of heat transfer takes place by copper cladding and that heat conduction along the length of PCB can be improved enormously by using even thin layer of copper. The results confirmed that temperatures of all the electronic components were within derated values. Meanwhile, it was known that convection also plays a significant role in the reduction of temperatures of the components. The reduction in nodal temperature was in the range of 13 to 42 %. Furthermore, altitude variation from sea level to 15240 m (above sea level) caused the reduction in pressure from 1atm to 0.1095 atm. Consequently, the temperature of the electronic components increased from 73.25 degree C to 83.83 degree C for first node 'a', and from 66.04 degree C to 68.47 degree C for last node 'n' because of the decrease in the convective heat transfer

  5. Local order origin of thermal stability enhancement in amorphous Ag doping GeTe

    Energy Technology Data Exchange (ETDEWEB)

    Xu, L.; Li, Y.; Yu, N. N.; Zhong, Y. P.; Miao, X. S., E-mail: miaoxs@mail.hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology (HUST), Wuhan 430074 (China); School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2015-01-19

    We demonstrate the impacts of Ag doping on the local atomic structure of amorphous GeTe phase-change material. The variations of phonon vibrational modes, boding nature, and atomic structure are shown by Raman, X-ray photoelectron spectroscopy, and ab initio calculation. Combining the experiments and simulations, we observe that the number of Ge atoms in octahedral site decreases and that in tetrahedral site increases. This modification in local order of GeTe originating from the low valence element will affect the crystallization behavior of amorphous GeTe, which is verified by differential scanning calorimetry and transmission electron microscope results. This work not only gives the analysis on the structural change of GeTe with Ag dopants but also provides a method to enhance the thermal stability of amorphous phase-change materials for memory and brain-inspired computing applications.

  6. Enhanced mechanical behavior of a nanocrystallised stainless steel and its thermal stability

    International Nuclear Information System (INIS)

    Roland, T.; Retraint, D.; Lu, K.; Lu, J.

    2007-01-01

    This paper discusses the mechanical properties of a nanocrystallised stainless steel obtained using surface mechanical attrition treatment (SMAT) and the underlying grain refinement mechanism using transmission electron microscopy (TEM). It was shown that grain refinement down to the nanometer range has the potential to significantly improve the mechanical properties of a 316L stainless steel which becomes comparable in strength to titanium alloys. Hence, promising structural applications could be considered for such a material. At the same time, the thermal stability of this nanocrystallised material was studied in the temperature range from 100 to 800 deg. C. The results show that the nanometer scaled microstructure is retained up to 600 deg. C and that a controlled annealing treatment could even lead to enhancement of both strength and ductility of this material. All these results are explained in terms of microstructural investigations, X-ray diffraction measurements, tensile and bending tests as well as microhardness measurements

  7. Enhanced mechanical behavior of a nanocrystallised stainless steel and its thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Roland, T. [ICD, LASMIS, University of Technology of Troyes, 10010 Troyes (France); Retraint, D. [ICD, LASMIS, University of Technology of Troyes, 10010 Troyes (France)]. E-mail: delphine.retraint@utt.fr; Lu, K. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110015 (China); Lu, J. [Department of Mechanical Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China)

    2007-02-15

    This paper discusses the mechanical properties of a nanocrystallised stainless steel obtained using surface mechanical attrition treatment (SMAT) and the underlying grain refinement mechanism using transmission electron microscopy (TEM). It was shown that grain refinement down to the nanometer range has the potential to significantly improve the mechanical properties of a 316L stainless steel which becomes comparable in strength to titanium alloys. Hence, promising structural applications could be considered for such a material. At the same time, the thermal stability of this nanocrystallised material was studied in the temperature range from 100 to 800 deg. C. The results show that the nanometer scaled microstructure is retained up to 600 deg. C and that a controlled annealing treatment could even lead to enhancement of both strength and ductility of this material. All these results are explained in terms of microstructural investigations, X-ray diffraction measurements, tensile and bending tests as well as microhardness measurements.

  8. Long-term thermal stability of Equal Channel Angular Pressed 2024 aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Güher, E-mail: guherkotan@gmail.com [Middle East Technical University, Metallurgical and Materials Engineering Department, 06800 Ankara (Turkey); Mersin University, Metallurgical and Materials Engineering Department, 33343 Yenisehir, Mersin (Turkey); Kalay, Y. Eren; Gür, C. Hakan [Middle East Technical University, Metallurgical and Materials Engineering Department, 06800 Ankara (Turkey)

    2016-11-20

    The strength of bulk metallic materials can be improved by creating ultra-fine grained structure via severe plastic deformation (SPD). However, the thermal stability of severely deformed materials has been a major issue that restricts their practical use within the industry. Although there are studies on the thermal stability of SPD metals, the long-term annealing response of particularly complex alloys, such as the age hardenable ones, remains undetermined. In the present study, annealing behavior of the single-pass Equal Channel Angular Pressed age hardenable 2024 Al alloy was investigated in the 0.38–0.52 homologous temperature range for up to 1000 h. Microstructures and the corresponding mechanical properties of the samples were determined by transmission electron microscopy, electron back-scatter diffraction analyses, and micro-hardness measurements. After long annealing durations at 80 °C and 120 °C, a secondary hardening was observed whereas a fast softening occurred at 200 °C. At 150 °C, however, a softening followed by a slight secondary hardening was also detected. The increased coarsening rate of S precipitates accompanied with dislocation annihilation was found to be the major cause of the hardness loss. Furthermore, dislocation-rich structure and Mg clusters remaining from the S precipitate dissolution eased the nucleation of Ω precipitates which are responsible for the secondary hardening. It was concluded that below 120 °C the single pass ECAPed Al 2024 components preserve their improved hardness for a prolonged period of time.

  9. Production and thermal stability of pure and Cr3+ -doped hydroxyapatite

    International Nuclear Information System (INIS)

    De Araujo, T S; De Souza, S O; De Sousa, E M B; Araujo, M S

    2010-01-01

    Hydroxyapatite (HAP) have been used as starting material for biomedical applications. The pure and Cr 3+ -doped hydroxyapatite were prepared by chemical precipitation reactions at 100, 500 e 800 0 C in order to investigate the thermal stability of these materials. The characterization of the thermal behavior of this phosphate, especially on the structural changes with heating, is very important for production of sunscreens The powders were characterized using chemical analysis: X-ray diffraction (XRD) and thermal analysis. The present study was successful in the preparation of pure hydroxyapatite and chromium substituted hydroxyapatites with good thermal stability and nanoparticles formation.

  10. Thermal stability analysis and auxiliary power feedback control for the tokamak engineering test breeder (TETB-II)

    International Nuclear Information System (INIS)

    Sheng Guangzhao

    1993-01-01

    The thermal stability of TETB-II is analyzed using different methods, viz., POPCON, linear stability analysis and the time evolution calculation of plasma parameters. A thermal instability of the TETB-II is predicted. Auxiliary power feedback control for thermal stability appears feasible and efficient

  11. Crystallization behaviour and thermal stability of two aluminium-based metallic glass powder materials

    Energy Technology Data Exchange (ETDEWEB)

    Li, X.P.; Yan, M. [University of Queensland, School of Mechanical and Mining Engineering, ARC Centre of Excellence for Design in Light Metals, Brisbane, QLD 4072 (Australia); Yang, B.J. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Wang, J.Q., E-mail: jqwang@imr.ac.cn [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Schaffer, G.B. [University of Queensland, School of Mechanical and Mining Engineering, ARC Centre of Excellence for Design in Light Metals, Brisbane, QLD 4072 (Australia); Qian, M., E-mail: ma.qian@uq.edu.au [University of Queensland, School of Mechanical and Mining Engineering, ARC Centre of Excellence for Design in Light Metals, Brisbane, QLD 4072 (Australia)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer The crystallization paths and products of Al{sub 86}Ni{sub 7}Y{sub 4.5}Co{sub 1}La{sub 1.5} powder have been identified. Black-Right-Pointing-Pointer The thermal stability of Al{sub 86}Ni{sub 7}Y{sub 4.5}Co{sub 1}La{sub 1.5} powder has been assessed. Black-Right-Pointing-Pointer The Al{sub 86}Ni{sub 7}Y{sub 4.5}Co{sub 1}La{sub 1.5} powder shows a wide processing window of 75 K. Black-Right-Pointing-Pointer The powder has the potential to be consolidated into thick BMG components based on the findings. Black-Right-Pointing-Pointer The Al{sub 85}Ni{sub 5}Y{sub 6}Co{sub 2}Fe{sub 2} powder shows similar characteristics but inferior thermal stability. - Abstract: The crystallization behaviour and thermal stability of two Al-based metallic glass powder materials, Al{sub 85}Ni{sub 5}Y{sub 6}Co{sub 2}Fe{sub 2} and Al{sub 86}Ni{sub 6}Y{sub 4.5}Co{sub 2}La{sub 1.5}, have been investigated using differential scanning calorimetry (DSC), X-ray diffraction (XRD) and electron microscopy. Both alloy powders show a distinct three-stage crystallization process with a similar gap of {approx}75 K between the onset crystallization temperature (T{sub x}) and the second crystallization temperature. Crystallization occurs by the precipitation and growth of fcc-Al, without intermetallic formation. The apparent activation energy for each stage of crystallization was determined from DSC analyses and the phases resulting from each crystallization stage were identified by XRD and electron microscopy. The critical cooling rate for each alloy powder was calculated from the DSC data. These results are necessary to inform the consolidation of amorphous powder particles of Al{sub 85}Ni{sub 5}Y{sub 6}Co{sub 2}Fe{sub 2} or Al{sub 86}Ni{sub 6}Y{sub 4.5}Co{sub 2}La{sub 1.5} into thick (>1 mm) metallic glass components.

  12. Investigating the Thermal and Phase Stability of Nanocrystalline Ni-W Produced by Electrodeposition, Sputtering, and Mechanical Alloying

    Science.gov (United States)

    Marvel, Christopher Jonathan

    The development of nanocrystalline materials has been increasingly pursued over the last few decades. They have been shown to exhibit superior properties compared to their coarse-grain counterparts, and thus present a tremendous opportunity to revolutionize the performance of nanoscale devices or bulk structural materials. However, nanocrystalline materials are highly prone to grain growth, and if the nanocrystalline grains coarsen, the beneficial properties are lost. There is a strong effort to determine the most effective thermal stability mechanisms to avoid grain growth, but the physical nature of nanocrystalline grain growth is still unclear due to a lack of detailed understanding of nanocrystalline microstructures. Furthermore, the influence of contamination has scarcely been explored with advanced transmission electron microscopy techniques, nor has there been a direct comparison of alloys fabricated with different bulk processes. Therefore, this research has applied aberration-corrected scanning transmission electron microscopy to characterize nanocrystalline Ni-W on the atomic scale and elucidate the physical grain growth behavior. Three primary objectives were pursued: (1) explore the thermal stability mechanisms of nanocrystalline Ni-W, (2) evaluate the phase stability of Ni-W and link any findings to grain growth behavior, and (3) compare the influences of bulk fabrication processing, including electrodeposition, DC magnetron sputtering, and mechanical alloying, on the thermal stability and phase stability of Ni-W. Several thermal stability mechanisms were identified throughout the course of this research. First and foremost, W-segregation was scarcely observed to grain boundaries, and it is unclear if W-segregation improves thermal stability contrary to most reports in the 2 literature. Long-range Ni4W chemical ordering was observed in alloys with more than 20 at.% W, and it is likely Ni4W domains reduce grain boundary mobility. In addition, lattice

  13. High electron thermal conductivity of chiral carbon nanotubes

    International Nuclear Information System (INIS)

    Mensah, S.Y.; Allotey, F.K.A.; Nkrumah, George; Mensah, N.G.

    2003-11-01

    Solving the Boltzmann kinetic equation with energy dispersion relation obtained in the tight binding approximation, the carrier thermal conductivity κ e of a chiral carbon nanotube (CCNT) was determined. The dependence of κ e on temperature T, chiral geometric angle φ h and overlap integrals Δ z and Δ s were obtained. The results were numerically analysed. Unusually high values of κ e were observed suggesting that ne is nontrivial in the calculation of the thermal conductivity κ of CCNT. More interestingly we noted also that at 104 K and for Δ z and Δ s values of 0.020 eV and 0.0150 eV respectively the κ e value is about 41000 W/mK as reported for a 99.9% pure 12 C crystal. We predict that the electron thermal conductivity of CCNT should exceed 200,000 W/mK at ∼ 80 K. (author)

  14. Preparation of shape-stabilized co-crystallized poly (ethylene glycol) composites as thermal energy storage materials

    International Nuclear Information System (INIS)

    Qian, Yong; Wei, Ping; Jiang, Pingkai; Li, Zhi; Yan, Yonggang; Ji, Kejian; Deng, Weihua

    2013-01-01

    Highlights: • Shape-stabilized PEG composites were prepared by sol–gel process. • The increased energy storage ability of composite was from cocrystallization effect. • Diammonium phosphate improved flame retardancy properties of PEG composite. • PEG composites had potential to be used as thermal energy storage materials. - Abstract: Shape-stabilized co-crystallized poly (ethylene glycol) (PEG) composites were prepared by sol–gel process. Tetraethoxysilane was utilized as supporting matrix precursor. The crystallization property as well as thermal energy storage properties of PEG was influenced by silica network. The combination of PEG 2k and PEG 10k with suitable ratio (3:1 by weight) led to synergistically increased fusion enthalpy attributed to cocrystallization effect. Furthermore, halogen-free flame retarded PEG composites were obtained using diammonium phosphate as flame retardant. With suitable composition, the latent heat value of flame retarded PEG composite was 96.7 kJ/kg accompanied with good thermal stability and improved flame retardancy properties. Fourier transform infrared spectrum (FT-IR), X-ray diffraction (XRD), polarized optical microscope (POM) and scanning electron microscope (SEM) were used to characterize the structure of PEG composites. Thermal stability properties of PEG composites were investigated by thermogravimetric analyzer (TGA). Char residue obtained from muffle furnace of PEG composites was analyzed by SEM and FT-IR. Flame retardancy properties of PEG composites were estimated by pyrolysis combustion flow calorimeter. Results showed that it was potential for shape-stabilized halogen-free flame retarded PEG composite to be applied in thermal energy storage field

  15. Screening of hydrocarbons as supercritical ORCs working fluids by thermal stability

    International Nuclear Information System (INIS)

    Dai, Xiaoye; Shi, Lin; An, Qingsong; Qian, Weizhong

    2016-01-01

    Highlights: • A rapid evaluation method for thermal stability of hydrocarbons for ORCs. • Methane and hydrogen are confirmed to be decomposition indicators. • The decomposition temperatures for some hydrocarbons using the rapid method. • Long carbon chain hydrocarbons are not suitable for supercritical ORCs. - Abstract: Organic Rankine Cycle (ORC) systems are widely used for industrial waste heat recovery and renewable energy utilization. The supercritical ORC is currently one of the main development directions due to its low exergy loss, high thermal efficiency and high work output. The thermal stability is the major limitation of organic working fluid selection with high temperature heat sources. This paper presents a rapid experimental method for assessing the thermal stability of hydrocarbons for ORCs. The fluids were tested in a high temperature reactor with methane and hydrogen theoretically and experimentally confirmed to be the indicators of thermal decomposition. The thermal decomposition temperatures were obtained for n-hexane, n-pentane, isopentane, cyclopentane, n-butane and isobutane using the rapid experimental method. The results show that cycloalkanes are not the good choices by thermal stability and long carbon chain hydrocarbons (longer than C6) are not suitable for supercritical ORCs due to the thermal stability limitation.

  16. Electron thermal confinement in a partially stochastic magnetic structure

    Science.gov (United States)

    Morton, L. A.; Young, W. C.; Hegna, C. C.; Parke, E.; Reusch, J. A.; Den Hartog, D. J.

    2018-04-01

    Using a high-repetition-rate Thomson scattering diagnostic, we observe a peak in electron temperature Te coinciding with the location of a large magnetic island in the Madison Symmetric Torus. Magnetohydrodynamic modeling of this quasi-single helicity plasma indicates that smaller adjacent islands overlap with and destroy the large island flux surfaces. The estimated stochastic electron thermal conductivity ( ≈30 m 2/s ) is consistent with the conductivity inferred from the observed Te gradient and ohmic heating power. Island-shaped Te peaks can result from partially stochastic magnetic islands.

  17. Preparation and properties of shape-stabilized phase change materials based on fatty acid eutectics and cellulose composites for thermal energy storage

    International Nuclear Information System (INIS)

    Cao, Lei; Tang, Yaojie; Fang, Guiyin

    2015-01-01

    Shape-stabilized fatty acid eutectics/carboxy methyl cellulose-1 composites as phase change materials (PCMs) were synthesized by absorbing liquid eutectics into the carboxy methyl cellulose-1 fibers. The chemical structure, crystalloid phase and morphology were determined by the Fourier transformation infrared spectroscope, X-ray diffractometer and scanning electronic microscope. The thermal properties and thermal stability were measured by the differential scanning calorimeter, thermogravimetric analyzer and the thermal cycling test, respectively. The results indicate that the eutectics are well adsorbed in the porous structure of the carboxy methyl cellulose-1. According to the DSC (differential scanning calorimeter) results, the composites melt at 32.2 °C with latent heat of 114.6 kJ/kg and solidify at 29.2 °C with latent heat of 106.8 kJ/kg. The thermal cycling test proves that the composites have good thermal reliability. It is envisioned that the prepared shape-stabilized PCMs have considerable potential for developing their roles in thermal energy storage. - Highlights: • The fatty acid eutectic/carboxy methyl cellulose-1 composites as PCMs were prepared. • Chemical structure and microstructure of composites were determined by FT-IR and SEM. • Thermal properties and stabilities were investigated by DSC and TGA. • The thermal cycling test confirmed that the composite has good thermal reliability

  18. Investigation of thermal management materials for automotive electronic control units

    International Nuclear Information System (INIS)

    Mallik, Sabuj; Ekere, Ndy; Best, Chris; Bhatti, Raj

    2011-01-01

    Today's electronics packages are smaller and more powerful than ever before. This leads to ever increasing thermal challenges for the systems designer. The automotive electronic control unit (ECU) package faces the same challenge of thermal management as the industry in general. This is coupled with the latest European Union legislation (Euro 6 standard) which forced the ECU manufacturers to completely re-design their ECU platform with improved hardware and software capability. This will result in increased power densities and therefore, the ability to dissipate heat will be a key factor. A higher thermal conductivity (TC) material for the ECU housing (than the currently used Aluminium) could improve heat dissipation from the ECU. This paper critically reviews the state-of-the-art in thermal management materials which may be applicable to an automotive ECU. This review shows that of the different materials currently available, the Al/SiC composites in particular have very good potential for automotive ECU application. In terms of metal composites processing, the liquid metal infiltration process is recommended as it has a lower processing cost and it also has the ability to produce near net-shape materials.

  19. Stability and electronic properties of low-dimensional nanostructures

    Science.gov (United States)

    Guan, Jie

    As the devices used in daily life become smaller and more concentrated, traditional three-dimensional (3D) bulk materials have reached their limit in size. Low-dimensional nanomaterials have been attracting more attention in research and getting widely applied in many industrial fields because of their atomic-level size, unique advanced properties, and varied nanostructures. In this thesis, I have studied the stability and mechanical and electronic properties of zero-dimensional (0D) structures including carbon fullerenes, nanotori, metallofullerenes and phosphorus fullerenes, one-dimensional (1D) structures including carbon nanotubes and phosphorus nanotubes, as well as two-dimensional (2D) structures including layered transition metal dichalcogenides (TMDs), phosphorene and phosphorus carbide (PC). I first briefly introduce the scientific background and the motivation of all the work in this thesis. Then the computational techniques, mainly density functional theory (DFT), are reviewed in Chapter 2. In Chapter 3, I investigate the stability and electronic structure of endohedral rare-earth metallofullerene La C60 and the trifluoromethylized La C60(CF3)n with n ≤ 5. Odd n is preferred due to the closed-shell electronic configuration or large HOMO-LUMO gap, which is also meaningful for the separation of C 60-based metallofullerenes. Mechanical and electronic properties of layered materials including TMDs and black phosphorus are studied in Chapter 4 and 5. In Chapter 4, a metallic NbSe2/semiconducting WSe2 bilayer is investigated and besides a rigid band shift associated with charge transfer, the presence of NbSe2 does not modify the electronic structure of WSe2. Structural similarity and small lattice mismatch results in the heterojunction being capable of efficiently transferring charge acrossthe interface. In Chapter 5, I investigate the dependence of stability and electronic band structure on the in-layer strain in bulk black phosphorus. In Chapters 6, 7 and

  20. Structure and Mechanical Properties of Al-Cu-Fe-X Alloys with Excellent Thermal Stability

    Directory of Open Access Journals (Sweden)

    Andrea Školáková

    2017-11-01

    Full Text Available In this work, the structure and mechanical properties of innovative Al-Cu-Fe based alloys were studied. We focused on preparation and characterization of rapidly solidified and hot extruded Al-Cu-Fe, Al-Cu-Fe-Ni and Al-Cu-Fe-Cr alloys. The content of transition metals affects mechanical properties and structure. For this reason, microstructure, phase composition, hardness and thermal stability have been investigated in this study. The results showed exceptional thermal stability of these alloys and very good values of mechanical properties. Alloying by chromium ensured the highest thermal stability, while nickel addition refined the structure of the consolidated alloy. High thermal stability of all tested alloys was described in context with the transformation of the quasicrystalline phases to other types of intermetallics.

  1. Thermal stability analysis and modelling of advanced perpendicular magnetic tunnel junctions

    Science.gov (United States)

    Van Beek, Simon; Martens, Koen; Roussel, Philippe; Wu, Yueh Chang; Kim, Woojin; Rao, Siddharth; Swerts, Johan; Crotti, Davide; Linten, Dimitri; Kar, Gouri Sankar; Groeseneken, Guido

    2018-05-01

    STT-MRAM is a promising non-volatile memory for high speed applications. The thermal stability factor (Δ = Eb/kT) is a measure for the information retention time, and an accurate determination of the thermal stability is crucial. Recent studies show that a significant error is made using the conventional methods for Δ extraction. We investigate the origin of the low accuracy. To reduce the error down to 5%, 1000 cycles or multiple ramp rates are necessary. Furthermore, the thermal stabilities extracted from current switching and magnetic field switching appear to be uncorrelated and this cannot be explained by a macrospin model. Measurements at different temperatures show that self-heating together with a domain wall model can explain these uncorrelated Δ. Characterizing self-heating properties is therefore crucial to correctly determine the thermal stability.

  2. Thermal conductivity and stability of nano size carbon black filled PDMS: Fuel cell perspective

    CSIR Research Space (South Africa)

    Chen, H

    2011-01-01

    Full Text Available Carbon black filled Polydimethylsiloxane (PDMS) was considered as a prospective bipolar plate material candidate for a Fuel Cell. In this perspective, thermal conductivity and stability of the composites were investigated. Samples with filler weight...

  3. Structure and Mechanical Properties of Al-Cu-Fe-X Alloys with Excellent Thermal Stability.

    Science.gov (United States)

    Školáková, Andrea; Novák, Pavel; Mejzlíková, Lucie; Průša, Filip; Salvetr, Pavel; Vojtěch, Dalibor

    2017-11-05

    In this work, the structure and mechanical properties of innovative Al-Cu-Fe based alloys were studied. We focused on preparation and characterization of rapidly solidified and hot extruded Al-Cu-Fe, Al-Cu-Fe-Ni and Al-Cu-Fe-Cr alloys. The content of transition metals affects mechanical properties and structure. For this reason, microstructure, phase composition, hardness and thermal stability have been investigated in this study. The results showed exceptional thermal stability of these alloys and very good values of mechanical properties. Alloying by chromium ensured the highest thermal stability, while nickel addition refined the structure of the consolidated alloy. High thermal stability of all tested alloys was described in context with the transformation of the quasicrystalline phases to other types of intermetallics.

  4. Cyclotron radiation from thermal and non-thermal electrons in the WEGA-stellarator

    International Nuclear Information System (INIS)

    Piekaar, H.W.; Rutgers, W.R.

    1980-11-01

    Electron cyclotron radiation measurements on the WEGA-stellarator are reported. Emission spectra around 2ωsub(ce) and 3ωsub(ce) were measured with a far-infra-red spectrometer and InSb detectors. When the plasma loop voltage is high, runaway electrons give rise to intense broad-band emission. Runaway particles can be removed by increasing the plasma density. For low loop voltage discharges the electron temperature profile was deduced from thermal emission around 2ωsub(ce). In spite of the low E-field, runaway particles are still created and pitch-angle scattered because ωsub(pe)/ωsub(ce) approximately 1. From non-thermal emission below 2ωsub(ce) and 3ωsub(ce) the energy and number of particles could be calculated, and was found to be in agreement with existing theories

  5. Electron thermal transport in tokamak: ETG or TEM turbulences?

    International Nuclear Information System (INIS)

    Lin, Z.; Chen, L.; Nishimura, Y.; Qu, H.; Hahm, T.S.; Lewandowski, J.; Rewoldt, G.; Wang, W.X.; Diamond, P.H.; Holland, C.; Zonca, F.; Li, Y.

    2005-01-01

    This paper reports progress on numerical and theoretical studies of electron transport in tokamak including: (1) electron temperature gradient turbulence; (2) trapped electron mode turbulence; and (3) a new finite element solver for global electromagnetic simulation. In particular, global gyrokinetic particle simulation and nonlinear gyrokinetic theory find that electron temperature gradient (ETG) instability saturates via nonlinear toroidal couplings, which transfer energy successively from unstable modes to damped modes preferably with longer poloidal wavelengths. The electrostatic ETG turbulence is dominated by nonlinearly generated radial streamers. The length of streamers scales with the device size and is much longer than the distance between mode rational surfaces or electron radial excursions. Both fluctuation intensity and transport level are independent of the streamer size. These simulations with realistic plasma parameters find that the electron heat conductivity is much smaller than the experimental value and in contrast with recent findings of flux-tube simulations that ETG turbulence is responsible for the anomalous electron thermal transport in fusion plasmas. The nonlinear toroidal couplings represent a new paradigm for the spectral cascade in plasma turbulence. (author)

  6. Theory of thermal conductivity in the disordered electron liquid

    Energy Technology Data Exchange (ETDEWEB)

    Schwiete, G., E-mail: schwiete@uni-mainz.de [Johannes Gutenberg Universität, Spin Phenomena Interdisciplinary Center (SPICE) and Institut für Physik (Germany); Finkel’stein, A. M. [Texas A& M University, Department of Physics and Astronomy (United States)

    2016-03-15

    We study thermal conductivity in the disordered two-dimensional electron liquid in the presence of long-range Coulomb interactions. We describe a microscopic analysis of the problem using the partition function defined on the Keldysh contour as a starting point. We extend the renormalization group (RG) analysis developed for thermal transport in the disordered Fermi liquid and include scattering processes induced by the long-range Coulomb interaction in the sub-temperature energy range. For the thermal conductivity, unlike for the electrical conductivity, these scattering processes yield a logarithmic correction that may compete with the RG corrections. The interest in this correction arises from the fact that it violates the Wiedemann–Franz law. We checked that the sub-temperature correction to the thermal conductivity is not modified either by the inclusion of Fermi liquid interaction amplitudes or as a result of the RG flow. We therefore expect that the answer obtained for this correction is final. We use the theory to describe thermal transport on the metallic side of the metal–insulator transition in Si MOSFETs.

  7. Theory of thermal conductivity in the disordered electron liquid

    International Nuclear Information System (INIS)

    Schwiete, G.; Finkel’stein, A. M.

    2016-01-01

    We study thermal conductivity in the disordered two-dimensional electron liquid in the presence of long-range Coulomb interactions. We describe a microscopic analysis of the problem using the partition function defined on the Keldysh contour as a starting point. We extend the renormalization group (RG) analysis developed for thermal transport in the disordered Fermi liquid and include scattering processes induced by the long-range Coulomb interaction in the sub-temperature energy range. For the thermal conductivity, unlike for the electrical conductivity, these scattering processes yield a logarithmic correction that may compete with the RG corrections. The interest in this correction arises from the fact that it violates the Wiedemann–Franz law. We checked that the sub-temperature correction to the thermal conductivity is not modified either by the inclusion of Fermi liquid interaction amplitudes or as a result of the RG flow. We therefore expect that the answer obtained for this correction is final. We use the theory to describe thermal transport on the metallic side of the metal–insulator transition in Si MOSFETs.

  8. Non-isothermal Crystallization, Thermal Stability, and Mechanical Performance of Poly(L-lactic acid/Barium Phenylphosphonate Systems

    Directory of Open Access Journals (Sweden)

    Cai Yan-Hua

    2017-11-01

    Full Text Available The introduction of a nucleating agent in semi-crystalline polymers is a frequently utilized way to improve the crystallization performance, and the use of a nucleating agent has a very great effect on the performance of the polymer in other areas including thermal stability and mechanical properties. In this investigation, barium phenylphosphonate (BaP was prepared as a crystallization accelerator for Poly(L-lactic acid (PLLA, and the non-isothermal crystallization behavior, thermal stability, and mechanical properties of PLLA modified by BaP were investigated using differential scanning calorimetry (DSC, X-ray diffraction (XRD, thermogravimetric analysis (TGA, and electronic tensile testing. Non-isothermal crystallization analysis showed that the BaP could significantly accelerate the crystallization of PLLA, and the non-isothermal crystallization peak shifted to a higher temperature with increasing concentration of BaP, however, the corresponding crystallization peak became wider. XRD results after non-isothermal crystallization confirmed the non-isothermal crystallization DSC results. Additionally, the addition of BaP did not change the crystal form of PLLA. A comparative study on thermal stability indicated that BaP decreased the onset decomposition temperature of PLLA, resulting from the formation of more tiny and imperfect crystals. Whereas the influence of BaP on the thermal decomposition profile of PLLA was negligible. In terms of mechanical properties, the tensile strength and elastic modulus of PLLA/BaP increased compared to the virgin PLLA, unfortunately, the elongation at break decreased.

  9. Thermal Stability Test of Sugar Alcohols as Phase Change Materials for Medium Temperature Energy Storage Application

    OpenAIRE

    Solé, Aran; Neumann, Hannah; Niedermaier, Sophia; Cabeza, Luisa F.; Palomo, Elena

    2014-01-01

    Sugar alcohols are potential phase change materials candidates as they present high phase change enthalpy values, are non-toxic and low cost products. Three promising sugar-alcohols were selected: D-mannitol, myo-inositol and dulcitol under high melting enthalpy and temperature criterion. Thermal cycling tests were performed to study its cycling stability which can be determining when selecting the suitable phase change material. D-mannitol and dulcitol present poor thermal stability...

  10. Structure and Mechanical Properties of Al-Cu-Fe-X Alloys with Excellent Thermal Stability

    OpenAIRE

    Školáková, Andrea; Novák, Pavel; Mejzlíková, Lucie; Průša, Filip; Salvetr, Pavel; Vojtěch, Dalibor

    2017-01-01

    In this work, the structure and mechanical properties of innovative Al-Cu-Fe based alloys were studied. We focused on preparation and characterization of rapidly solidified and hot extruded Al-Cu-Fe, Al-Cu-Fe-Ni and Al-Cu-Fe-Cr alloys. The content of transition metals affects mechanical properties and structure. For this reason, microstructure, phase composition, hardness and thermal stability have been investigated in this study. The results showed exceptional thermal stability of these allo...

  11. A first principles study of the electronic structure, elastic and thermal properties of UB2

    Science.gov (United States)

    Jossou, Ericmoore; Malakkal, Linu; Szpunar, Barbara; Oladimeji, Dotun; Szpunar, Jerzy A.

    2017-07-01

    Uranium diboride (UB2) has been widely deployed for refractory use and is a proposed material for Accident Tolerant Fuel (ATF) due to its high thermal conductivity. However, the applicability of UB2 towards high temperature usage in a nuclear reactor requires the need to investigate the thermomechanical properties, and recent studies have failed in highlighting applicable properties. In this work, we present an in-depth theoretical outlook of the structural and thermophysical properties of UB2, including but not limited to elastic, electronic and thermal transport properties. These calculations were performed within the framework of Density Functional Theory (DFT) + U approach, using Quantum ESPRESSO (QE) code considering the addition of Coulomb correlations on the uranium atom. The phonon spectra and elastic constant analysis show the dynamic and mechanical stability of UB2 structure respectively. The electronic structure of UB2 was investigated using full potential linear augmented plane waves plus local orbitals method (FP-LAPW+lo) as implemented in WIEN2k code. The absence of a band gap in the total and partial density of states confirms the metallic nature while the valence electron density plot reveals the presence of covalent bond between adjacent B-B atoms. We predicted the lattice thermal conductivity (kL) by solving Boltzmann Transport Equation (BTE) using ShengBTE. The second order harmonic and third-order anharmonic interatomic force constants required as input to ShengBTE was calculated using the Density-functional perturbation theory (DFPT). However, we predicted the electronic thermal conductivity (kel) using Wiedemann-Franz law as implemented in Boltztrap code. We also show that the sound velocity along 'a' and 'c' axes exhibit high anisotropy, which accounts for the anisotropic thermal conductivity of UB2.

  12. Thermal stability and fracture toughness of epoxy resins modified with epoxidized castor oil and Al2O3 nanoparticles

    International Nuclear Information System (INIS)

    Zhu, Lin; Jin, Fanlong; Park, Soojin

    2012-01-01

    This study examined the effects of the epoxidized castor oil (ECO) and Al 2 O 3 content on the thermal stability and fracture toughness of the diglycidylether of bisphenol-A (DGEBA)/ECO/Al 2 O 3 ternary composites using a range of techniques. The thermal stability of the composites was decreased by the addition of ECO and Al 2 O 3 nanoparticles. The fracture toughness of the composites was improved significantly by the addition of ECO and Al 2 O 3 nanoparticles. The composite containing 3 wt % Al 2 O 3 nanoparticles showed the maximum flexural strength. Scanning electron microscopy (SEM) revealed tortuous cracks in the DGEBA/ECO/Al 2 O 3 composites, which prevented deformation and crack propagation

  13. Preparation of polyurethane/montmorillonite nanocomposites by solution: characterization using low-field NMR and study of thermal stability

    International Nuclear Information System (INIS)

    Silva, Marcos Anacleto da; Tavares, Maria Ines B.

    2009-01-01

    Polyurethanes (PU) are important and versatile class of polymer materials, especially because of their desirable properties, such as high abrasion resistance, tear strength, excellent shock absorption, flexibility and elasticity. However, there also exist some disadvantages, for example, low thermal stability and barrier properties. To overcome the disadvantages, research on novel polyurethane/clay nanocomposites has been carried out. The investigation of the structure of polyurethane/clay nanocomposites has been mostly done by X-ray diffraction (XRD) and transmission electron microscopy (TEM). In this work, PU/clay films were prepared by solution, and the obtained nanocomposites were characterized by XRD and low-field nuclear magnetic resonance (NMR). Low field NMR measurements were able to provide important information on molecular dynamics of the polymeric nanocomposites PU/OMMT. In addition, they also confirmed the results obtained by XRD. The thermal stability was determined by thermogravimetric analysis (TGA). (author)

  14. Thermal stability of double-ceramic-layer thermal barrier coatings with various coating thickness

    International Nuclear Information System (INIS)

    Dai Hui; Zhong Xinghua; Li Jiayan; Zhang Yanfei; Meng Jian; Cao Xueqiang

    2006-01-01

    Double-ceramic-layer (DCL) coatings with various thickness ratios composed of YSZ (6-8 wt.% Y 2 O 3 + ZrO 2 ) and lanthanum zirconate (LZ, La 2 Zr 2 O 7 ) were produced by the atmospheric plasma spraying. Chemical stability of LZ in contact with YSZ in DCL coatings was investigated by calcining powder blends at different temperatures. No obvious reaction was observed when the calcination temperature was lower than 1250 deg. C, implying that LZ and YSZ had good chemical applicability for producing DCL coating. The thermal cycling test indicate that the cycling lives of the DCL coatings are strongly dependent on the thickness ratio of LZ and YSZ, and the coatings with YSZ thickness between 150 and 200 μm have even longer lives than the single-layer YSZ coating. When the YSZ layer is thinner than 100 μm, the DCL coatings failed in the LZ layer close to the interface of YSZ layer and LZ layer. For the coatings with the YSZ thickness above 150 μm, the failure mainly occurs at the interface of the YSZ layer and the bond coat

  15. Thermal stability of carbon-encapsulated Fe-Nd-B nanoparticles

    International Nuclear Information System (INIS)

    Bystrzejewski, M.; Cudzilo, S.; Huczko, A.; Lange, H.

    2006-01-01

    Thermal stability of various magnetic nanomaterials is very essential, due to their prospective future applications. In this paper, thermal behaviour of the carbon-encapsulated Fe-Nd-B nanoparticles is studied. These nanostructures were produced by direct current arcing of carbon anodes filled with Nd 2 Fe 14 B material. The thermogravimetry and differential thermal analysis curves were recorded in an oxygen atmosphere. The thermal processes were monitored by X-ray diffraction to follow the changes in the phase composition. The investigated samples have been thermally stable up to 600 K

  16. Non-thermal plasma instabilities induced by deformation of the electron energy distribution function

    Science.gov (United States)

    Dyatko, N. A.; Kochetov, I. V.; Napartovich, A. P.

    2014-08-01

    Non-thermal plasma is a key component in gas lasers, microelectronics, medical applications, waste gas cleaners, ozone generators, plasma igniters, flame holders, flow control in high-speed aerodynamics and others. A specific feature of non-thermal plasma is its high sensitivity to variations in governing parameters (gas composition, pressure, pulse duration, E/N parameter). This sensitivity is due to complex deformations of the electron energy distribution function (EEDF) shape induced by variations in electric field strength, electron and ion number densities and gas excitation degree. Particular attention in this article is paid to mechanisms of instabilities based on non-linearity of plasma properties for specific conditions: gas composition, steady-state and decaying plasma produced by the electron beam, or by an electric current pulse. The following effects are analyzed: the negative differential electron conductivity; the absolute negative electron mobility; the stepwise changes of plasma properties induced by the EEDF bi-stability; thermo-current instability and the constriction of the glow discharge column in rare gases. Some of these effects were observed experimentally and some of them were theoretically predicted and still wait for experimental confirmation.

  17. Finite length thermal equilibria of a pure electron plasma column

    International Nuclear Information System (INIS)

    Prasad, S.A.; O'Neil, T.M.

    1979-01-01

    The electrons of a pure electron plasma may be in thermal equilibrium with each other and still be confined by static magnetic and electric fields. Since the electrons make a significant contribution to the electric field, only certain density profiles are consistent with Poisson's equation. The class of such distributions for a finite length cylindrical column is investigated. In the limit where the Debye length is small compared with the dimensions of the column, the density is essentially constant out to some surface of revolution and then falls off abruptly. The falloff in density is a universal function when measured along the local normal to the surface of revolution and scaled in terms of the Debye length. The solution for the shape of the surface of revolution is simplified by passage to the limit of zero Debye length

  18. Enhancement of thermal stability of silver(I) acetylacetonate by platinum(II) acetylacetonate

    Czech Academy of Sciences Publication Activity Database

    Křenek, T.; Kovářík, T.; Pola, M.; Jakubec, Ivo; Bezdička, Petr; Bastl, Zdeněk; Pokorná, Dana; Urbanová, Markéta; Galíková, Anna; Pola, Josef

    2013-01-01

    Roč. 554, FEB (2013), s. 1-7 ISSN 0040-6031 Institutional support: RVO:61388980 ; RVO:61388955 ; RVO:67985858 Keywords : thermal gravimetric analysis * differential scanning calorimetry * silver(I) acetylacetonate * platinum(II) acetylacetonate * enhancement of thermal stability Subject RIV: CA - Inorganic Chemistry; CF - Physical ; Theoretical Chemistry (UFCH-W) Impact factor: 2.105, year: 2013

  19. Lignin-based carbon fibers: Carbon nanotube decoration and superior thermal stability

    KAUST Repository

    Xu, Xuezhu; Zhou, Jian; Jiang, Long; Lubineau, Gilles; Payne, Scott A.; Gutschmidt, David

    2014-01-01

    and the properties of the resultant products were studied and compared. The CF–CNT hybrid structure produced at 850 °C using a palladium catalyst showed the highest thermal stability, i.e., 98.3% residual weight at 950 °C. A mechanism for such superior thermal

  20. Synthesis, characterization, and thermal stability of SiO2/TiO2/CR-Ag multilayered nanostructures

    Science.gov (United States)

    Díaz, Gabriela; Chang, Yao-Jen; Philipossian, Ara

    2018-06-01

    The controllable synthesis and characterization of novel thermally stable silver-based particles are described. The experimental approach involves the design of thermally stable nanostructures by the deposition of an interfacial thick, active titania layer between the primary substrate (SiO2 particles) and the metal nanoparticles (Ag NPs), as well as the doping of Ag nanoparticles with an organic molecule (Congo Red, CR). The nanostructured particles were composed of a 330-nm silica core capped by a granular titania layer (10 to 13 nm in thickness), along with monodisperse 5 to 30 nm CR-Ag NPs deposited on top. The titania-coated support (SiO2/TiO2 particles) was shown to be chemically and thermally stable and promoted the nucleation and anchoring of CR-Ag NPs, which prevented the sintering of CR-Ag NPs when the structure was exposed to high temperatures. The thermal stability of the silver composites was examined by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). Larger than 10 nm CR-Ag NPs were thermally stable up to 300 °C. Such temperature was high enough to destabilize the CR-Ag NPs due to the melting point of the CR. On the other hand, smaller than 10 nm Ag NPs were stable at temperatures up to 500 °C because of the strong metal-metal oxide binding energy. Energy dispersion X-ray spectroscopy (EDS) was carried out to qualitatively analyze the chemical stability of the structure at different temperatures which confirmed the stability of the structure and the existence of silver NPs at temperatures up to 500 °C.

  1. Investigation for thermal stability of U3Si2 and protection methods

    International Nuclear Information System (INIS)

    Zhang Huiying; Sun Jichang; Sun Rongxian

    1994-08-01

    The thermal stability of U 3 Si 2 in Ar, N 2 and air, and the interaction between U 3 Si 2 and Al, Zr have been investigated by thermal analysis method. According to the results of thermal analysis, protection measures for various procedures have been improved. From the practice, it shows that the protection measures can ensure the safety of production and raise the product quality as well as reduce the cost effectively

  2. Thermal Shock Resistance of Stabilized Zirconia/Metal Coat on Polymer Matrix Composites by Thermal Spraying Process

    Science.gov (United States)

    Zhu, Ling; Huang, Wenzhi; Cheng, Haifeng; Cao, Xueqiang

    2014-12-01

    Stabilized zirconia/metal coating systems were deposited on the polymer matrix composites by a combined thermal spray process. Effects of the thicknesses of metal layers and ceramic layer on thermal shock resistance of the coating systems were investigated. According to the results of thermal shock lifetime, the coating system consisting of 20 μm Zn and 125 μm 8YSZ exhibited the best thermal shock resistance. Based on microstructure evolution, failure modes and failure mechanism of the coating systems were proposed. The main failure modes were the formation of vertical cracks and delamination in the outlayer of substrate, and the appearance of coating spallation. The residual stress, thermal stress and oxidation of substrate near the substrate/metal layer interface were responsible for coating failure, while the oxidation of substrate near the substrate/coating interface was the dominant one.

  3. Polymer/Silicate Nanocomposites Developed for Improved Strength and Thermal Stability

    Science.gov (United States)

    Campbell, Sandi G.

    2003-01-01

    Over the past decade, polymer-silicate nanocomposites have been attracting considerable attention as a method of enhancing polymer properties. The nanometer dimensions of the dispersed silicate reinforcement can greatly improve the mechanical, thermal, and gas barrier properties of a polymer matrix. In a study at the NASA Glenn Research Center, the dispersion of small amounts (less than 5 wt%) of an organically modified layered silicate (OLS) into the polymer matrix of a carbon-fiber-reinforced composite has improved the thermal stability of the composite. The enhanced barrier properties of the polymer-clay hybrid are believed to slow the diffusion of oxygen into the bulk polymer, thereby slowing oxidative degradation of the polymer. Electron-backscattering images show cracking of a nanocomposite matrix composite in comparison to a neat resin matrix composite. The images show that dispersion of an OLS into the matrix resin reduces polymer oxidation during aging and reduces the amount of cracking in the matrix significantly. Improvements in composite flexural strength, flexural modulus, and interlaminar shear strength were also obtained with the addition of OLS. An increase of up to 15 percent in these mechanical properties was observed in composites tested at room temperature and 288 C. The best properties were seen with low silicate levels, 1 to 3 wt%, because of the better dispersion of the silicate in the polymer matrix.

  4. Hierarchical evolution and thermal stability of microstructure with deformation twins in 316 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S.J. [Department of Materials Science and Engineering, Texas A& M University, College Station, TX 77843 (United States); Jozaghi, T. [Department of Mechanical Engineering, Texas A& M University, College Station, TX 77843 (United States); Karaman, I., E-mail: ikaraman@tamu.edu [Department of Materials Science and Engineering, Texas A& M University, College Station, TX 77843 (United States); Department of Mechanical Engineering, Texas A& M University, College Station, TX 77843 (United States); Arroyave, R. [Department of Materials Science and Engineering, Texas A& M University, College Station, TX 77843 (United States); Department of Mechanical Engineering, Texas A& M University, College Station, TX 77843 (United States); Chumlyakov, Y.I. [Siberian Physical Technical Institute, Tomsk State University, Tomsk 634050 (Russian Federation)

    2017-05-10

    We report extensive nano-twin formation in 316 stainless steel (SS) and the evolution of a hierarchical microstructure through the formation of multi-scale twin bundles after uniaxial tension with uniform elongation levels of 20%, 30%, and 40%. Multiscale characterization techniques were employed to reveal the nature of these twins. The twin density increases with the increasing strain level, however, the twin width remains the same, notably reducing the mean free path of dislocations. Concurrently, significant work hardening is observed during subsequent deformation. The deformation-induced nano-twins are thermally stable up to ~800 °C, shown by both interrupted and in-situ transmission electron microscopy experiments, above which the recrystallization takes place in the vicinity of the twins. Such favorable thermal stability of the twins in nano-twin strengthened 316 SS offers a promising approach for microstructurally engineering these materials for potential applications at elevated temperatures. The related strengthening mechanisms are discussed in the light of the mean free path of dislocations and the dislocation interactions with twin boundaries.

  5. Thermal stability analysis of thin film Ni-NiOx-Cr tunnel junctions

    International Nuclear Information System (INIS)

    Krishnan, S.; Emirov, Y.; Bhansali, S.; Stefanakos, E.; Goswami, Y.

    2010-01-01

    This research reports on the thermal stability of Ni-NiO x -Cr based Metal-Insulator-Metal (MIM) junction. Effect of annealing (250 to 400 o C) on the electrical and physical transport properties of this MIM stack was understood to determine the thermal budget allowable when using these diodes. MIM tunnel junctions were fabricated by sputtering and the NiO x was formed through reactive sputtering. The performance of the tunnel junctions after exposure to elevated temperatures was investigated using current-voltage measurements. This was correlated to the structural properties of the interfaces at different temperatures, characterized by Atomic Force Microscopy, X-ray Diffraction and Transmission Electron Microscopy (TEM). MIM tunnel junctions annealed up to 350 o C demonstrated satisfactory current-voltage characteristics and sensitivity. MIM junctions exhibited improved electrical performance as they were heated to 250 o C (sensitivity of 42 V -1 and a zero-bias resistance of ∼300 Ω) due to improved crystallization of the layers within the stack. At temperatures over 350 o C, TEM and Energy Dispersive Spectra confirmed a breakdown of the MIM structure due to interdiffusion.

  6. Mechanical and Thermal Stability Properties of Modified Rice Straw Fiber Blend with Polycaprolactone Composite

    Directory of Open Access Journals (Sweden)

    Roshanak Khandanlou

    2014-01-01

    Full Text Available The goal of this study was to investigate the effect of modified rice straw (ORS on the mechanical and thermal properties of modified rice straw/polycaprolactone composites (ORS/PCL-Cs. The composites (Cs of polycaprolactone (PCL with ORS were successfully synthesized using the solution-casting method. The RS modified with octadecylamine (ODA as an organic modifier. The prepared composites were characterized by using powder X-ray diffraction (XRD, thermogravimetric analysis (TGA, scanning electron microscopy (SEM, and Fourier transforms infrared spectroscopy (FT-IR, and mechanical properties were investigated. Composites of ORS/PCL showed superior mechanical properties due to greater compatibility of ORS with PCL. The XRD results showed that the intensity of the peaks decreased with the increase of ORS content from 1.0 to 7.0 wt.% in comparison with PCL peaks. Tensile measurement showed an increase in tensile modulus but a decrease in tensile strength and elongation at break as the ORS contents are increased from 1.0 to 7.0 wt.%; on the other hand, tensile strength was improved with the addition of 5.0 wt.% of ORS. Thermal stability was decreased with the increase of ORS contents. SEM micrograph indicated good dispersion of ORS into the matrix, and FT-IR spectroscopy showed that the interaction between PCL and ORS is physical interaction.

  7. Synergistic effect and mechanism of platinum catalyst and nitrogen-containing silane on the thermal stability of silicone rubber

    International Nuclear Information System (INIS)

    Chen, Wanjuan; Zeng, Xingrong; Lai, Xuejun; Li, Hongqiang; Fang, Weizhen; Liu, Tian

    2016-01-01

    Highlights: • Platinum (Pt) and nitrogen-containing silane (NS) were introduced into silicone rubber. • The thermal stability was improved by Pt/NS both under nitrogen and air atmosphere. • The TG-FTIR of evolved gases during degradation was performed. • The synergistic effect and mechanism of Pt and NS were proposed. - Abstract: Platinum (Pt) catalyst and nitrogen-containing silane (NS) were introduced to improve the thermal stability of silicone rubber. The effects of Pt and NS on thermal stability and degradation mechanism of silicone rubber were investigated by thermogravimetry (TG), thermogravimetry-Fourier transform infrared spectrometry (TG-FTIR), scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDXS) and Fourier transform infrared spectrometry (FTIR). A significant synergism was found between Pt and NS for improving the thermal stability of silicone rubber. When 6.67 ppm of Pt and 1.4 phr of NS were introduced, the temperature of 10% and 20% weight loss under nitrogen atmosphere were respectively increased by 36 °C and 119 °C. Meanwhile, the residue weight at 900 °C was doubled to 68% in the presence of Pt/NS. The synergistic mechanism might be that the nitrogen atom coordinated with Pt and improved the catalytic efficiency of Pt. Additionally, NS preserved the catalytic activity of Pt under air atmosphere. Hence, Pt/NS efficiently catalyzed thermal crosslinking and suppressed degradation of silicone chains. Moreover, it revealed that the presence of Pt/NS protected silicone chains from oxidation. Thus, the unzipping depolymerization by silanol groups was reduced significantly.

  8. Synergistic effect and mechanism of platinum catalyst and nitrogen-containing silane on the thermal stability of silicone rubber

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wanjuan; Zeng, Xingrong, E-mail: psxrzeng@gmail.com; Lai, Xuejun; Li, Hongqiang; Fang, Weizhen; Liu, Tian

    2016-05-20

    Highlights: • Platinum (Pt) and nitrogen-containing silane (NS) were introduced into silicone rubber. • The thermal stability was improved by Pt/NS both under nitrogen and air atmosphere. • The TG-FTIR of evolved gases during degradation was performed. • The synergistic effect and mechanism of Pt and NS were proposed. - Abstract: Platinum (Pt) catalyst and nitrogen-containing silane (NS) were introduced to improve the thermal stability of silicone rubber. The effects of Pt and NS on thermal stability and degradation mechanism of silicone rubber were investigated by thermogravimetry (TG), thermogravimetry-Fourier transform infrared spectrometry (TG-FTIR), scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDXS) and Fourier transform infrared spectrometry (FTIR). A significant synergism was found between Pt and NS for improving the thermal stability of silicone rubber. When 6.67 ppm of Pt and 1.4 phr of NS were introduced, the temperature of 10% and 20% weight loss under nitrogen atmosphere were respectively increased by 36 °C and 119 °C. Meanwhile, the residue weight at 900 °C was doubled to 68% in the presence of Pt/NS. The synergistic mechanism might be that the nitrogen atom coordinated with Pt and improved the catalytic efficiency of Pt. Additionally, NS preserved the catalytic activity of Pt under air atmosphere. Hence, Pt/NS efficiently catalyzed thermal crosslinking and suppressed degradation of silicone chains. Moreover, it revealed that the presence of Pt/NS protected silicone chains from oxidation. Thus, the unzipping depolymerization by silanol groups was reduced significantly.

  9. Star formation through thermal instability of radiative plasma with finite electron inertia and finite Larmor radius corrections

    Energy Technology Data Exchange (ETDEWEB)

    Kaothekar, Sachin, E-mail: sackaothekar@gmail.com [Department of Physics, Mahakal Institute of Technology, Ujjain-456664, Madhya Pradesh (India)

    2016-08-15

    I have studied the effects of finite electron inertia, finite ion Larmor radius (FLR) corrections, and radiative heat-loss function on the thermal instability of an infinite homogeneous, viscous plasma incorporating the effect of thermal conductivity for star formation in interstellar medium (ISM). A general dispersion relation is derived using the normal mode analysis method with the help of relevant linearized perturbation equations of the problem. The wave propagation is discussed for longitudinal and transverse directions to the external magnetic field and the conditions of modified thermal instabilities and stabilities are discussed in different cases. We find that the thermal instability criterion is get modified into radiative instability criterion by inclusion of radiative heat-loss functions with thermal conductivity. The viscosity of medium removes the effect of FLR corrections from the condition of radiative instability. Numerical calculation shows stabilizing effect of heat-loss function, viscosity and FLR corrections, and destabilizing effect of finite electron inertia on the thermal instability. Results carried out in this paper shows that stars are formed in interstellar medium mainly due to thermal instability.

  10. Star formation through thermal instability of radiative plasma with finite electron inertia and finite Larmor radius corrections

    Directory of Open Access Journals (Sweden)

    Sachin Kaothekar

    2016-08-01

    Full Text Available I have studied the effects of finite electron inertia, finite ion Larmor radius (FLR corrections, and radiative heat-loss function on the thermal instability of an infinite homogeneous, viscous plasma incorporating the effect of thermal conductivity for star formation in interstellar medium (ISM. A general dispersion relation is derived using the normal mode analysis method with the help of relevant linearized perturbation equations of the problem. The wave propagation is discussed for longitudinal and transverse directions to the external magnetic field and the conditions of modified thermal instabilities and stabilities are discussed in different cases. We find that the thermal instability criterion is get modified into radiative instability criterion by inclusion of radiative heat-loss functions with thermal conductivity. The viscosity of medium removes the effect of FLR corrections from the condition of radiative instability. Numerical calculation shows stabilizing effect of heat-loss function, viscosity and FLR corrections, and destabilizing effect of finite electron inertia on the thermal instability. Results carried out in this paper shows that stars are formed in interstellar medium mainly due to thermal instability.

  11. Thermal stability and electrochemical properties of PVP-protected Ru nanoparticles synthesized at room temperature

    Science.gov (United States)

    Kumar, Manish; Devi, Pooja; Shivling, V. D.

    2017-08-01

    Stable ruthenium nanoparticles (RuNPs) have been synthesized by the chemical reduction of ruthenium trichloride trihydrate (RuCl3 · 3H2O) using sodium borohydride (NaBH4) as a reductant and polyvinylpyrrolidone (PVP) as a protecting agent in the aqueous medium at room temperature. The nanoparticles thus prepared were characterized by their morphology and structural analysis from transmission electron microscopy (TEM), X-ray powder diffraction (XRD), UV-vis spectroscopy, Fourier transformation infrared and thermogravimetric analysis (TGA) techniques. The TEM image suggested a homogeneous distribution of PVP-protected RuNPs having a small average diameter of 2-4 nm with a chain-like network structure. The XRD pattern also confirmed that a crystallite size is around 2 nm of PVP-protected RuNPs having a single broad peak. The thermal stability studied using TGA, indicated good stability and the electrochemical properties of these nanoparticles revealed that saturation current increases for PVP-protected RuNPs/GC.

  12. Cooled electronic system with liquid-cooled cold plate and thermal spreader coupled to electronic component

    Science.gov (United States)

    Chainer, Timothy J.; Graybill, David P.; Iyengar, Madhusudan K.; Kamath, Vinod; Kochuparambil, Bejoy J.; Schmidt, Roger R.; Steinke, Mark E.

    2018-03-27

    Apparatus and method are provided for facilitating cooling of an electronic component. The apparatus includes a liquid-cooled cold plate and a thermal spreader associated with the cold plate. The cold plate includes multiple coolant-carrying channel sections extending within the cold plate, and a thermal conduction surface with a larger surface area than a surface area of the component to be cooled. The thermal spreader includes one or more heat pipes including multiple heat pipe sections. One or more heat pipe sections are partially aligned to a first region of the cold plate, that is, where aligned to the surface to be cooled, and partially aligned to a second region of the cold plate, which is outside the first region. The one or more heat pipes facilitate distribution of heat from the electronic component to coolant-carrying channel sections of the cold plate located in the second region of the cold plate.

  13. Thermal Degradation Mechanism of a Thermostable Polyester Stabilized with an Open-Cage Oligomeric Silsesquioxane

    Directory of Open Access Journals (Sweden)

    Yolanda Bautista

    2017-12-01

    Full Text Available A polyester composite was prepared through the polymerization of an unsaturated ester resin with styrene and an open-cage oligomeric silsesquioxane with methacrylate groups. The effect of the open-cage oligomeric silsesquioxane on the thermal stability of the thermostable polyester was studied using both thermogravimetric analysis and differential thermal analysis. The results showed that the methacryl oligomeric silsesquioxane improved the thermal stability of the polyester. The decomposition mechanism of the polyester/oligomer silsesquioxane composite was proposed by Fourier transform infrared spectroscopy (FTIR analysis of the volatiles.

  14. Effect of Filler Concentration on Thermal Stability of Vinyl Copolymer Elastomer (VCE) Composites

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Dali [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hubbard, Kevin Mark [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Devlin, David James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Henderson, Kevin C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pacheco, Robin Montoya [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-03-06

    To study the thermal stability of vinyl copolymer elastomer (VCE) in its composite form, systematic TGA characterizations were conducted in both nonisothermal and isothermal modes. The effects of filler concentration on the aging behaviors of the VCE/filler composites were investigated under nitroplasticizer (NP) environment. FTIR characterization was used to probe the structural changes in the VCE polymer before and after the thermal treatments. This study suggests that the filler concentration significantly deteriorates the thermal stability of NP at a moderate temperature (< 70 °C). The degradation of NP, in turn, accelerates the aging process of the VCE polymer in its composite form.

  15. Effectiveness of electronic stability control on single-vehicle accidents

    DEFF Research Database (Denmark)

    Lyckegaard, Allan; Hels, Tove; Bernhoft, Inger Marie

    2015-01-01

    the injury severity categories (slight, severe, and fatal). Conclusions: In line with previous results, this study concludes that ESC reduces the risk for single-vehicle injury accidents by 31% when controlling for various confounding factors related to the driver, the car, and the accident surroundings......Objective: This study aims at evaluating the effectiveness of electronic stability control (ESC) on single-vehicle injury accidents while controlling for a number of confounders influencing the accident risk. Methods: Using police-registered injury accidents from 2004 to 2011 in Denmark with cars...... the following were significant. For the driver: Age, gender, driving experience, valid driving license, and seat belt use. For the vehicle: Year of registration, weight, and ESC. For the accident surroundings: Visibility, light, and location. Finally, for the road: Speed limit, surface, and section...

  16. Thermal expansion model for multiphase electronic packaging materials

    International Nuclear Information System (INIS)

    Allred, B.E.; Warren, W.E.

    1991-01-01

    Control of thermal expansion is often necessary in the design and selection of electronic packages. In some instances, it is desirable to have a coefficient of thermal expansion intermediate between values readily attainable with single or two phase materials. The addition of a third phase in the form of fillers, whiskers, or fibers can be used to attain intermediate expansions. To help design the thermal expansion of multiphase materials for specific applications, a closed form model has been developed that accurately predicts the effective elastic properties of isotropic filled materials and transversely isotropic lamina. Properties of filled matrix materials are used as inputs to the lamina model to obtain the composite elastic properties as a function of the volume fraction of each phase. Hybrid composites with two or more fiber types are easily handled with this model. This paper reports that results for glass, quartz, and Kevlar fibers with beta-eucryptite filled polymer matrices show good agreement with experimental results for X, Y, and Z thermal expansion coefficients

  17. Thermal Management and Reliability of Power Electronics and Electric Machines

    Energy Technology Data Exchange (ETDEWEB)

    Narumanchi, Sreekant

    2016-08-03

    Increasing the number of electric-drive vehicles (EDVs) on America's roads has been identified as a strategy with near-term potential for dramatically decreasing the nation's dependence on oil -- by the U.S. Department of Energy, the federal cross-agency EV-Everywhere Challenge, and the automotive industry. Mass-market deployment will rely on meeting aggressive technical targets, including improved efficiency and reduced size, weight, and cost. Many of these advances will depend on optimization of thermal management. Effective thermal management is critical to improving the performance and ensuring the reliability of EDVs. Efficient heat removal makes higher power densities and lower operating temperatures possible, and in turn enables cost and size reductions. The National Renewable Energy Laboratory (NREL), along with DOE and industry partners is working to develop cost-effective thermal management solutions to increase device and component power densities. In this presentation, the activities in recent years related to thermal management and reliability of automotive power electronics and electric machines will be presented.

  18. Thermal Management and Reliability of Power Electronics and Electric Machines

    Energy Technology Data Exchange (ETDEWEB)

    Narumanchi, Sreekant

    2016-06-13

    Increasing the number of electric-drive vehicles (EDVs) on America's roads has been identified as a strategy with near-term potential for dramatically decreasing the nation's dependence on oil - by the U.S. Department of Energy, the federal cross-agency EV-Everywhere Challenge, and the automotive industry. Mass-market deployment will rely on meeting aggressive technical targets, including improved efficiency and reduced size, weight, and cost. Many of these advances will depend on optimization of thermal management. Effective thermal management is critical to improving the performance and ensuring the reliability of EDVs. Efficient heat removal makes higher power densities and lower operating temperatures possible, and in turn enables cost and size reductions. The National Renewable Energy Laboratory (NREL), along with DOE and industry partners is working to develop cost-effective thermal management solutions to increase device and component power densities. In this presentation, the activities in recent years related to thermal management and reliability of automotive power electronics and electric machines are presented.

  19. Electronic properties of thermally formed thin iron oxide films

    International Nuclear Information System (INIS)

    Wielant, J.; Goossens, V.; Hausbrand, R.; Terryn, H.

    2007-01-01

    The oxide layer, present between an organic coating and the substrate, guarantees adhesion of the coating and plays a determinating role in the delamination rate of the organic coating. The purpose of this study is to compare the resistive and semiconducting properties of thermal oxides formed on steel in two different atmospheres at 250 deg. C: an oxygen rich atmosphere, air, and an oxygen deficient atmosphere, N 2 . In N 2 , a magnetite layer grows while in air a duplex oxide film forms composed by an inner magnetite layer and a thin outer hematite scale. The heat treatment for different amounts of time at high temperature was used as method to sample the thickness variation and change in electronic and semiconducting properties of the thermal oxide layers. Firstly, linear voltammetric measurements were performed to have a first insight in the electrochemical behavior of the thermal oxides in a borate buffer solution. Electrochemical impedance spectroscopy in the same buffer combined with the Mott-Schottky analysis were used to determine the semiconducting properties of the thermal oxides. By spectroscopic ellipsometry (SE) and atomic force microscopy (AFM), respectively, the thickness and roughness of the oxide layers were determined supporting the physical interpretation of the voltammetric and EIS data. These measurements clearly showed that oxide layers with different constitution, oxide resistance, flatband potential and doping concentration can be grown by changing the atmosphere

  20. Comparative study of thermal stability of magnetostrictive biosensor between two kinds of biorecognition elements

    International Nuclear Information System (INIS)

    Ye, Xue-mei; Guntupalli, R.; Lakshmanan, R.S.; Chin, Bryan A.; Hu, Jing

    2014-01-01

    Magnetostrictive biosensors specific to Salmonella typhimurium were prepared by immobilizing antibody or phage as biorecognition elements onto the magnetostrictive sensor platform. The sensors were stored at temperatures of 25 °C (room temperature), 45 °C and 65 °C, respectively, and the ability to bind S. typhimurium was detected by testing the resonant frequency shift using a HP network analyzer after exposure to 1 mL of 1 × 10 9 cfu/mL of S. typhimurium at a predetermined schedule. The binding of S. typhimurium to biosensors was confirmed by Scanning Electron Microscopy (SEM). The results showed that there existed an initial sudden drop in the average density of S. typhimurium bound to the biosensor surface versus duration at different temperatures for the two kinds of recognition elements, and the binding ability to S. typhimurium of phage-immobilized biosensors was much better than that of antibody-immobilized biosensors, with longevity longer than 30 days at all tested temperatures, though decreasing gradually over the testing period. While the longevity of antibody-immobilized biosensors was only about 30, 8 and 5 days at room temperature (25 °C), 45 °C and 65 °C, respectively. Meanwhile, the activation energy of the two kinds of biosensors was investigated, and it was found that phage immobilized sensors showed much higher activation energy than antibody immobilized sensors, which resulted in less dependency on temperature and thus having much better thermal stability than antibody immobilized sensors. - Highlights: • Phage immobilized biosensors has much better thermal stability. • The longevity of phage immobilized biosensors was longer than 30 days even at 65 °C. • The activation energy of phage immobilized biosensors is much higher

  1. Comparative study of thermal stability of magnetostrictive biosensor between two kinds of biorecognition elements

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Xue-mei [School of Materials Science and Engineering, Changzhou University, Changzhou 213164 (China); Guntupalli, R.; Lakshmanan, R.S.; Chin, Bryan A. [Materials Research and Education Center, Auburn University, AL 36849 (United States); Hu, Jing, E-mail: jinghoo@126.com [School of Materials Science and Engineering, Changzhou University, Changzhou 213164 (China); Materials Research and Education Center, Auburn University, AL 36849 (United States)

    2014-08-01

    Magnetostrictive biosensors specific to Salmonella typhimurium were prepared by immobilizing antibody or phage as biorecognition elements onto the magnetostrictive sensor platform. The sensors were stored at temperatures of 25 °C (room temperature), 45 °C and 65 °C, respectively, and the ability to bind S. typhimurium was detected by testing the resonant frequency shift using a HP network analyzer after exposure to 1 mL of 1 × 10{sup 9} cfu/mL of S. typhimurium at a predetermined schedule. The binding of S. typhimurium to biosensors was confirmed by Scanning Electron Microscopy (SEM). The results showed that there existed an initial sudden drop in the average density of S. typhimurium bound to the biosensor surface versus duration at different temperatures for the two kinds of recognition elements, and the binding ability to S. typhimurium of phage-immobilized biosensors was much better than that of antibody-immobilized biosensors, with longevity longer than 30 days at all tested temperatures, though decreasing gradually over the testing period. While the longevity of antibody-immobilized biosensors was only about 30, 8 and 5 days at room temperature (25 °C), 45 °C and 65 °C, respectively. Meanwhile, the activation energy of the two kinds of biosensors was investigated, and it was found that phage immobilized sensors showed much higher activation energy than antibody immobilized sensors, which resulted in less dependency on temperature and thus having much better thermal stability than antibody immobilized sensors. - Highlights: • Phage immobilized biosensors has much better thermal stability. • The longevity of phage immobilized biosensors was longer than 30 days even at 65 °C. • The activation energy of phage immobilized biosensors is much higher.

  2. Assessment of Accrued Damage and Remaining Useful Life in Leadfree Electronics Subjected to Multiple Thermal Environments of Thermal Aging and Thermal Cycling

    Data.gov (United States)

    National Aeronautics and Space Administration — A method has been developed for prognostication of accrued prior damage in electronics subjected to overlapping sequential environments of thermal aging and thermal...

  3. Vehicle rollover risk and electronic stability control systems.

    Science.gov (United States)

    MacLennan, P A; Marshall, T; Griffin, R; Purcell, M; McGwin, G; Rue, L W

    2008-06-01

    Electronic stability control (ESC) systems were developed to reduce motor vehicle collisions (MVCs) caused by loss of control. Introduced in Europe in 1995 and in the USA in 1996, ESC is designed to improve vehicle lateral stability by electronically detecting and automatically assisting drivers in unfavorable situations. To examine the relationship between vehicle rollover risk and presence of ESC using a large national database of MVCs. A retrospective cohort study for the period 1995 through 2006 was carried out using data obtained from the National Automotive Sampling System General Estimates System. All passenger cars and sport utility vehicles (SUVs)/vans of model year 1996 and later were eligible. Vehicle ESC (unavailable, optional, standard) was determined on the basis of make, model, and model year. Risk ratios (RRs) and 95% CIs were calculated to compare rollover risk by vehicle ESC group. For all crashes, vehicles equipped with standard ESC had decreased risk of rollover (RR = 0.62, 95% CI 0.50 to 0.77) compared with vehicles with ESC unavailable. The association was consistent for single-vehicle MVCs (RR = 0.61, 95% CI 0.46 to 0.82); passenger cars had decreased rollover risk (RR = 0.77, 95% CI 0.52 to 1.12), but SUVs/vans had a more dramatically decreased risk (RR = 0.40, 95% CI 0.26 to 0.61). This study supports previous results showing ESC to be effective in reducing the risk of rollover. ESC is more effective in SUVs/vans for rollovers related to single-vehicle MVCs.

  4. Experimental studies of thermal and non-thermal electron cyclotron phenomena in tokamaks

    International Nuclear Information System (INIS)

    McDermott, F.S.

    1984-12-01

    A direct measurement of wave absorption in the ISX-B tokamak at the second harmonic of the electron cyclotron frequency is reported. Measurements of the absorption of a wave polarized in the extraordinary mode and propagating perpendicular to the toroidal magnetic field are in agreement with the absorption predicted by the linearized Vlasov equation for a thermal plasma. Agreement is found both for an analytic approximation to the wave absorption and for a numerical simulation of ray propagation in toroidal geometry. Observations are also reported on a non-linear, three-wave interaction process occurring during high power electron cyclotron resonance heating in the Versator II tokamak. The measured spectra and the threshold power are consistent with a model in which the incident power in the extraordinary mode of polarization decays at the upper hybrid resonance layer into a lower hybrid wave and an electron Bernstein wave. Finally, measurements of non-thermal emission at the second harmonic of the electron cyclotron frequency and below the electron plasma frequency are reported from low density, non-Maxwellian plasma in the Versator II tokamak. The emission spectra are in agreement with a model in which waves are driven unstable at the anomalous Doppler resonance, while only weakly damped at the Cerenkov resonance

  5. Electron thermalization in rare gases and their mixtures

    International Nuclear Information System (INIS)

    Bronic, I.K.; Kimura, M.

    1996-01-01

    The time evolution and temperature dependence of electron energy distribution functions (EDFs) are studied in pure rare gases (He, Ne, Ar, Kr, Xe) as well as in their mixtures by using solutions of the Boltzmann equation. A clear difference between the gases having the Ramsauer endash Townsend (RT) minimum in the momentum-transfer cross section, (RT gases: Ar, Kr, and Xe), and those without the RT minimum (non-RT gases: He and Ne) is pointed out. The influence of the position and the depth of the RT minimum on the EDF and time evolution is studied for three different initial electron energies. A formula proposed for describing thermalization time in a mixture is tested on (i) a non-RT endash non-RT gas mixture, (ii) a RT endash non-RT mixture and (iii) a RT endash RT gas mixture. The linear combination of the reciprocal thermalization times in gas mixture with the component concentrations as weighting factors is found to be valid for gases with a similar energy dependence of the momentum-transfer cross section, σ m , and also for all rare-gas binary mixtures if the initial electron energy is sufficiently below the RT minimum. Conspicuous deviations from the linear relationship are observed in mixtures of gases whose energy dependence of σ m (or the stopping cross section) are different, and theoretical rationales for these findings are provided. copyright 1996 American Institute of Physics

  6. Phase Behavior, Thermal Stability and Rheological Properties of PPEK/PC Blends

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Phase behavior, thermal stability and rheological properties of the blends of poly(phthalazinone ether ketone) (PPEK)with bisphenol-A polycarbonate (PC) prepared by solution coprecipitation were studied using differential scanning calorimetry (DSC), Frourier-Transform IR spectroscopy (FT-IR), thermogravimetric analysis (TGA) and capillary rheometer. The DSC results indicated that PPEK/PC blends are almost immiscible in full compositions. FT-IR investigation showed that there were no apparent specific interactions between the constituent polymers. The blends keep excellent thermal stability and the addition of PC degrades the thermal stability of blends to some degree. The thermal degradation processes of the blends are much similar to that of PC. The studies on rheological properties of blends show that blending PPEK with PC is beneficial to reducing the melt viscosity and improving the appearance of PPEK.

  7. Polymer stabilization of the smectic C-alpha* liquid crystal phase—Over tenfold thermal stabilization by confining networks of photo-polymerized reactive mesogens

    International Nuclear Information System (INIS)

    Labeeb, A.; Gleeson, H. F.; Hegmann, T.

    2015-01-01

    The smectic C*-alpha (SmC α *) phase is one of the sub-phases of ferroelectric liquid crystals that has drawn much interest due to its electro-optical properties and ultrafast switching. Generally observed above the ferroelectric SmC* phase in temperature, the SmC α * commonly shows only very narrow phase temperature range of a few degree Celsius. To broaden the SmC α * phase, polymer stabilization was investigated for thermal phase stabilization. Two different reactive monomers were tested in three mixtures, and all three broadened the temperature range of the SmC α * phase from 3 °C to 39 °C. The current reversal method was used to determine the phase existence versus temperature. Moreover, the texture and network structure was studied by polarized optical microscopy and scanning electron microscopy, with the latter revealing the confinement of the smectic layer structure within the porous polymer network

  8. Analysis of protein stability and ligand interactions by thermal shift assay.

    Science.gov (United States)

    Huynh, Kathy; Partch, Carrie L

    2015-02-02

    Purification of recombinant proteins for biochemical assays and structural studies is time-consuming and presents inherent difficulties that depend on the optimization of protein stability. The use of dyes to monitor thermal denaturation of proteins with sensitive fluorescence detection enables rapid and inexpensive determination of protein stability using real-time PCR instruments. By screening a wide range of solution conditions and additives in a 96-well format, the thermal shift assay easily identifies conditions that significantly enhance the stability of recombinant proteins. The same approach can be used as an initial low-cost screen to discover new protein-ligand interactions by capitalizing on increases in protein stability that typically occur upon ligand binding. This unit presents a methodological workflow for small-scale, high-throughput thermal denaturation of recombinant proteins in the presence of SYPRO Orange dye. Copyright © 2015 John Wiley & Sons, Inc.

  9. Polyetherimide/bucky gels nanocomposites with superior conductivity and thermal stability

    KAUST Repository

    Chen, Ye

    2013-08-14

    Polyetherimide (PEI) nanocomposites comprising bucky gels of industrial-grade multiwalled carbon nanotubes (MWCNTs) and ionic liquid (IL, 1-butyl-3-methyl imidazolium hexafluorophosphate ([BMIM][PF6])) were prepared. The processing framework for this nanocomposite is simple, reproducible, and easily scalable. The strong interaction between IL and MWCNTs caused the latter to uniformly disperse in the PEI matrix while IL flowed into the gaps between the nanotubes\\' walls. The nanocomposite exhibited an enhanced conductivity of 2.01 × 104 Ω·cm volume resistivity at room temperature; the value decreased dramatically by 12 orders of magnitude, compared to pristine PEI. The IL free ions and MWCNTs networks provided excellent channels for electron transfer. PEI/bucky gels nanocomposites also showed improved thermal stability and high tensile strength. Other than having antiwear properties, this material can have numerous applications in the aerospace and electronics industries. Moreover, our work presents a "green" method toward modified nanocomposites industrial production as IL is environmentally safe and is easily recyclable. © 2013 American Chemical Society.

  10. Polyetherimide/bucky gels nanocomposites with superior conductivity and thermal stability

    KAUST Repository

    Chen, Ye; Tao, Jing; Deng, Lin; LI, LIANG; Li., Jun; Yang, Yang; Khashab, Niveen M.

    2013-01-01

    Polyetherimide (PEI) nanocomposites comprising bucky gels of industrial-grade multiwalled carbon nanotubes (MWCNTs) and ionic liquid (IL, 1-butyl-3-methyl imidazolium hexafluorophosphate ([BMIM][PF6])) were prepared. The processing framework for this nanocomposite is simple, reproducible, and easily scalable. The strong interaction between IL and MWCNTs caused the latter to uniformly disperse in the PEI matrix while IL flowed into the gaps between the nanotubes' walls. The nanocomposite exhibited an enhanced conductivity of 2.01 × 104 Ω·cm volume resistivity at room temperature; the value decreased dramatically by 12 orders of magnitude, compared to pristine PEI. The IL free ions and MWCNTs networks provided excellent channels for electron transfer. PEI/bucky gels nanocomposites also showed improved thermal stability and high tensile strength. Other than having antiwear properties, this material can have numerous applications in the aerospace and electronics industries. Moreover, our work presents a "green" method toward modified nanocomposites industrial production as IL is environmentally safe and is easily recyclable. © 2013 American Chemical Society.

  11. Thermal stability of Ti{sub 3}SiC{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Emmerlich, Jens [Linkoeping University, Department of Physics, IFM, Thin Film Physics Division, SE-581 83 Linkoeping (Sweden)]. E-mail: jenem@ifm.liu.se; Music, Denis [Materials Chemistry, RWTH Aachen University, Kopernikusstrasse 16, D-52074 Aachen (Germany); Eklund, Per [Linkoeping University, Department of Physics, IFM, Thin Film Physics Division, SE-581 83 Linkoeping (Sweden); Wilhelmsson, Ola [Uppsala University, Department of Materials Chemistry, The Angstroem Laboratory, P.O. Box 538, SE-751 21 Uppsala (Sweden); Jansson, Ulf [Uppsala University, Department of Materials Chemistry, The Angstroem Laboratory, P.O. Box 538, SE-751 21 Uppsala (Sweden); Schneider, Jochen M. [Materials Chemistry, RWTH Aachen University, Kopernikusstrasse 16, D-52074 Aachen (Germany); Hoegberg, Hans [Linkoeping University, Department of Physics, IFM, Thin Film Physics Division, SE-581 83 Linkoeping (Sweden); Hultman, Lars [Linkoeping University, Department of Physics, IFM, Thin Film Physics Division, SE-581 83 Linkoeping (Sweden)

    2007-02-15

    The thermal stability of Ti{sub 3}SiC{sub 2}(0 0 0 1) thin films is studied by in situ X-ray diffraction analysis during vacuum furnace annealing in combination with X-ray photoelectron spectroscopy, transmission electron microscopy and scanning transmission electron microscopy with energy dispersive X-ray analysis. The films are found to be stable during annealing at temperatures up to {approx}1000 deg. C for 25 h. Annealing at 1100-1200 deg. C results in the rapid decomposition of Ti{sub 3}SiC{sub 2} by Si out-diffusion along the basal planes via domain boundaries to the free surface with subsequent evaporation. As a consequence, the material shrinks by the relaxation of the Ti{sub 3}C{sub 2} slabs and, it is proposed, by an in-diffusion of O into the empty Si-mirror planes. The phase transformation process is followed by the detwinning of the as-relaxed Ti{sub 3}C{sub 2} slabs into (1 1 1)-oriented TiC{sub 0.67} layers, which begin recrystallizing at 1300 deg. C. Ab initio calculations are provided supporting the presented decomposition mechanisms.

  12. Thermal stability of Ti3SiC2 thin films

    International Nuclear Information System (INIS)

    Emmerlich, Jens; Music, Denis; Eklund, Per; Wilhelmsson, Ola; Jansson, Ulf; Schneider, Jochen M.; Hoegberg, Hans; Hultman, Lars

    2007-01-01

    The thermal stability of Ti 3 SiC 2 (0 0 0 1) thin films is studied by in situ X-ray diffraction analysis during vacuum furnace annealing in combination with X-ray photoelectron spectroscopy, transmission electron microscopy and scanning transmission electron microscopy with energy dispersive X-ray analysis. The films are found to be stable during annealing at temperatures up to ∼1000 deg. C for 25 h. Annealing at 1100-1200 deg. C results in the rapid decomposition of Ti 3 SiC 2 by Si out-diffusion along the basal planes via domain boundaries to the free surface with subsequent evaporation. As a consequence, the material shrinks by the relaxation of the Ti 3 C 2 slabs and, it is proposed, by an in-diffusion of O into the empty Si-mirror planes. The phase transformation process is followed by the detwinning of the as-relaxed Ti 3 C 2 slabs into (1 1 1)-oriented TiC 0.67 layers, which begin recrystallizing at 1300 deg. C. Ab initio calculations are provided supporting the presented decomposition mechanisms

  13. Thermal stability of hydroxyapatite in biphasic calcium phosphate ceramics

    CSIR Research Space (South Africa)

    Nilen, RWN

    2008-04-01

    Full Text Available temperatures greater than 1125 C. Because the HA/b-TCP ratio dominantly determines the rate and extent of BCP resorption in vivo, the possible thermal decomposition of HA during BCP synthesis must be considered, particularly if high temperature treatments...

  14. Discrete Diffusion Monte Carlo for Electron Thermal Transport

    Science.gov (United States)

    Chenhall, Jeffrey; Cao, Duc; Wollaeger, Ryan; Moses, Gregory

    2014-10-01

    The iSNB (implicit Schurtz Nicolai Busquet electron thermal transport method of Cao et al. is adapted to a Discrete Diffusion Monte Carlo (DDMC) solution method for eventual inclusion in a hybrid IMC-DDMC (Implicit Monte Carlo) method. The hybrid method will combine the efficiency of a diffusion method in short mean free path regions with the accuracy of a transport method in long mean free path regions. The Monte Carlo nature of the approach allows the algorithm to be massively parallelized. Work to date on the iSNB-DDMC method will be presented. This work was supported by Sandia National Laboratory - Albuquerque.

  15. Thermal stability and microstructure of catalytic alumina composite support with lanthanum species

    Energy Technology Data Exchange (ETDEWEB)

    Ozawa, Masakuni, E-mail: ozawa@numse.nagoya-u.ac.jp; Nishio, Yoshitoyo

    2016-09-01

    Highlights: • Thermal stability of La-modified γ-Al{sub 2}O{sub 3} with nanometer-scaled structure. • LaAlO{sub 3} particles are dispersed in the aggregated particles of alumina. • Increase of the surface basicity of La modified alumina using CO{sub 2}-TPD. - Abstract: Lanthanum (La) modified γ-alumina composite was examined for application toward thermostable catalytic support at elevated temperature. La added alumina was prepared through an aqueous process using lanthanum (III) nitrate and then characterized by surface area measurement, X-ray powder diffraction (XRD), differential thermal analysis (DTA), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoemission spectroscopy (XPS) and surface desorption of CO{sub 2}. It was found that the properties depended on the La content and heat treatment temperatures. The characterization of the surface, structural and chemical properties of La-Al{sub 2}O{sub 3} showed the existence of a strong interaction between the La species and alumina via formation of new phase and modified surface in Al{sub 2}O{sub 3} samples. LaAlO{sub 3} nanoparticle formed among alumina particles by the solid phase reaction of Al{sub 2}O{sub 3} and La{sub 2}O{sub 3}. The increase of the surface basicity of La modified alumina was demonstrated using CO{sub 2} temperature programmed desorption experiments. The controlled surface interaction between La oxide and alumina provide the unique surface and structural properties of the resulting mixed oxides as catalysts and catalytic supports.

  16. PREFACE: Eurotherm Seminar 102: Thermal Management of Electronic Systems

    Science.gov (United States)

    Punch, J.; Walsh, E.

    2014-07-01

    About EUROTHERM The aim of the EUROTHERM Committee (www.eurothermcommittee.eu) is to promote and foster European cooperation in Thermal Sciences and Heat Transfer by gathering together scientists and engineers working in specialized areas. The Committee consists of members representing and appointed by national bodies in the EU countries. The current President of EUROTHERM is Professor Anton van Steenhoven from the University of Eindhoven (The Netherlands). The Committee organizes and coordinates European scientific events such as the EUROTHERM Seminars (about 4 per year) and the European Thermal Sciences Conference (every 4 years). About EUROTHERM Seminar 102 (www.eurothermseminar102.com) This seminar, part of the long-running series of European seminars on the thermal sciences, took place in June 2014 at the University of Limerick in Limerick, Ireland. The seminar addressed the topic of 'Thermal Management of Electronic Systems', a critical contemporary application area which represents a vibrant challenge for practitioners of the thermal sciences. We convey special thanks to the reviewers who have evaluated these papers. We also thank the scientific committee, consisting of internationally recognized experts. Their role has been to manage the evaluation of abstracts and the papers selection process as co-coordinators for specific topics. This seminar was hosted by the Stokes Institute at the University of Limerick. It could not have been organized without the efficient help of our administrators and technicians for IT support. This volume of Journal of Physics: Conference Series includes 27 articles presented at the seminar. Dr. Jeff Punch, Chair Stokes Institute, University of Limerick, Limerick, Ireland Email: jeff.punch@ul.ie Prof. Edmond Walsh, Co-Chair Associate Professor, Osney Laboratories, Department of Engineering Science, University of Oxford, UK Email: edmond.walsh@bnc.ox.ac.uk

  17. Bounds of thermal stability of infinite cylindrical structures with non-uniform internal heat generation

    International Nuclear Information System (INIS)

    Gadalla, M.A.

    1992-01-01

    This paper presents an overview analyses of the thermal instability or thermal viability of infinite cylindrical structures with non-linear and non-uniform internal heat generation. The structure may be subjected to different and combined boundary conditions. An analytical solution is obtained for the generalized problem in spite of the non-linearity and the non-homogeneity of the source term. Four case studies with different boundary conditions are presented. The analyses show that the critical parameter for thermal stability may be though of as an altitude of surface below which the cylindrical structure will be thermally stable and performance worthy. The results also show that the bounds of thermal stability of a cylindrical structure system (solid or hollow) is eminently determined by the boundary conditions to which the system is subjected and can significantly alter the life-span of the structure

  18. Preparation and thermal conductivity enhancement of composite phase change materials for electronic thermal management

    International Nuclear Information System (INIS)

    Wu, Weixiong; Zhang, Guoqing; Ke, Xiufang; Yang, Xiaoqing; Wang, Ziyuan; Liu, Chenzhen

    2015-01-01

    Highlights: • A kind of composite phase change material board (PCMB) is prepared and tested. • PCMB presents a large thermal storage capacity and enhanced thermal conductivity. • PCMB displays much better cooling effect in comparison to natural air cooling. • PCMB presents different cooling characteristics in comparison to ribbed radiator. - Abstract: A kind of phase change material board (PCMB) was prepared for use in the thermal management of electronics, with paraffin and expanded graphite as the phase change material and matrix, respectively. The as-prepared PCMB presented a large thermal storage capacity of 141.74 J/g and enhanced thermal conductivity of 7.654 W/(m K). As a result, PCMB displayed much better cooling effect in comparison to natural air cooling, i.e., much lower heating rate and better uniformity of temperature distribution. On the other hand, compared with ribbed radiator technology, PCMB also presented different cooling characteristics, demonstrating that they were suitable for different practical application

  19. Thermal stability of diamond-like carbon–MoS{sub 2} thin films in different environments

    Energy Technology Data Exchange (ETDEWEB)

    Niakan, H., E-mail: hamid.niakan@usask.ca [Department of Mechanical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9 (Canada); Zhang, C. [Department of Mechanical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9 (Canada); Hu, Y. [Canadian Light Source, 101 Perimeter Road, Saskatoon, SK S7N 0X4 (Canada); Szpunar, J.A.; Yang, Q. [Department of Mechanical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9 (Canada)

    2014-07-01

    Diamond-like carbon (DLC) based coatings are ideal for low friction and wear resistant applications. For those tribological applications, the coatings may expose to high temperature environments. Therefore, the thermal stability of the coating is very important for its long-term performance. In this work, DLC–MoS{sub 2} composite thin films were synthesized using biased target ion beam deposition technique in which MoS{sub 2} was produced by sputtering a MoS{sub 2} target using Ar ion beams while DLC was deposited by an ion source with CH{sub 4} gas as carbon source. DLC films without MoS{sub 2} deposited under similar conditions were used as reference samples. After the deposition, DLC and DLC–MoS{sub 2} thin films were heat-treated in ambient air and low pressure environments at different temperatures ranging from 100 to 600 °C for 2 h. The effect of annealing on the structure, mechanical and tribological properties of the resulting films were studied by means of Raman spectroscopy, X-ray absorption near edge structure, scanning electron microscopy, nanoindentation, and ball-on-disk testing. The results showed that the structure, hardness, Young's modulus, friction coefficient and wear coefficient of the DLC films were stable up to 200 °C annealing in air and 300 °C in low pressure. At higher temperature, the annealing led to the transformation of sp{sup 3} to sp{sup 2}, which degraded the mechanical and tribological properties of the thin films. Comparing with the DLC films, the DLC–MoS{sub 2} thin films showed a slower rate of graphitization and higher structure stability throughout the range of annealing temperatures, indicating a relatively higher thermal stability. - Highlights: • Thermal stability of diamond-like carbon (DLC) and DLC–MoS{sub 2} films were evaluated. • DLC–MoS{sub 2} films can be synthesized by biased target ion beam deposition technique. • Comparing with DLC films, the DLC–MoS{sub 2} thin films showed higher

  20. Co-simulation of heavy truck tire dynamics and electronic stability control systems (phase A).

    Science.gov (United States)

    2009-07-01

    Electronic stability control (ESC) systems have been proven to be an effective means of preventing instability and loss of control on both passenger vehicles and heavy trucks. In addition, roll stability algorithms are an effective means of reducing ...

  1. From Molecular Electronics to Solar Thermal Energy Storage

    DEFF Research Database (Denmark)

    Olsen, Stine Tetzschner

    The Sun's signicant resource potential provides a solution for the world's increasing energy demand in a sustainable and responsible manner. However, the intrinsic property of the on-o cycles of the solar irradiation, i.e. daynight, sunny-cloudy, and summer-winter, constitutes a signicant challenge...... for the utilization of solar energy. An eective technology for storing the solar energy is required. This thesis focuses on solar thermal energy storage in molecules, since it oers a very compact and eective storage method. The rst chapter after the introduction of the thesis, chapter two, introduces the fundamental...... properties of the molecule, i.e. the electronic behaviour of the molecule in dierent environments, which is a key property for investigations of solar energy storage. The main focus of the research is on the electron transport in the Coulomb blockade regime. The third chapter goes into the challenge...

  2. Encapsulation of β-carotene within ferritin nanocages greatly increases its water-solubility and thermal stability.

    Science.gov (United States)

    Chen, Lingli; Bai, Guangling; Yang, Rui; Zang, Jiachen; Zhou, Ting; Zhao, Guanghua

    2014-04-15

    Carotenoids may play a number of potential health benefits for human. However, their use in food industry is limited mostly because of their poor water-solubility and low thermal stability. Ferritins are widely distributed in nature with a shell-like structure which offers a great opportunity to improve the water-solubility and thermal stability of the carotenoids by encapsulation. In this work, recombinant human H-chain ferritin (rHuHF) was prepared and used to encapsulate β-carotene, a typical compound among carotenoids, by taking advantage of the reversible dissociation and reassembly characteristic of apoferritin in different pH environments. Results from high-performance liquid chromatography (HPLC), UV/Vis spectroscopy and transmission electron microscope (TEM) indicated that β-carotene molecules were successfully encapsulated within protein cages with a β-carotene/protein molar ratio of 12.4-1. Upon such encapsulation, these β-carotene-containing apoferritin nanocomposites were water-soluble. Interestingly, the thermal stability of the β-carotene encapsulated within apoferritin nanocages was markedly improved as compared to free β-carotene. These new properties might be favourable to the utilisation of β-carotene in food industry. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Preparation, melting behavior and thermal stability of poly(lactic acid)/poly(propylene carbonate) blends processed by vane extruder

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Wei, E-mail: zw55624@163.com; Chen, Rongyuan; Zhang, Haichen; Qu, Jinping, E-mail: jpqu@scut.edu.cn [National Engineering Research Center of Novel Equipment for Polymer Processing, South China University of Technology, Guangzhou 510640 (China)

    2016-03-09

    Poly (lactic acid) (PLA)/Poly (propylene carbonate) (PPC) blends were prepared by vane extruder which is a type of novel polymer processing extruder based on elongation force field. Scanning electron microscope (SEM), differential scanning calorimetry (DSC) and thermogravimetric (TG) were used respectively to analyze the compatibility, the melting behavior and thermal stability properties of PLA/PPC blends affected by the different content of PPC. The results showed that with the increase of the PPC content, the glass transition temperature of PLA was reduced, and the glass transition temperature of PPC was increased, which indicated that PLA and PPC had partial compatibility. The cold crystallization temperature of PLA increased with the increase of the PPC content, which showed that PPC hindered the cold crystallization process of PLA. The addition of PPC had little impact on the melting process of PLA, and the melting temperature of PLA was almost kept the same value. Thermogravimetric analysis showed that the thermal stability of PPC was worse than that of PLA, the addition of PPC reduced the thermal stability of PLA.

  4. Models of electron conductivity which lead to ablation stabilization of fluid instabilities in laser-driven implosions

    International Nuclear Information System (INIS)

    Lindl, J.D.; Mead, W.C.

    1975-01-01

    LASNEX calculations with a modified electron conductivity show the existence of a firepolishing stabilization effect. By modifying the thermal conductivity so that K α T/sup n//rho/sup m/, one is able to construct a situation in which the electrons deposit their energy in a thin layer at the ablation surface and closely match the zero order solutions assumed earlier. The firepolishing effect appears to require that a significant fraction of the total pressure be due to the ablation process itself rather than the thermal pressure in the corona gas. It also requires KL approximately 1 where L is the scale height for decay of thermal perturbations generated at the ablation surface. For classical electron conductivity, because the thermal flux depends linearly on the grams/cm 2 necessary to stop the electrons, (1/rho) nabla rho approximately (1/T) nabla T near the ablation surface so that the pressure is nearly constant across the ablation surface. Hence there is no ablation pressure as such and no firepolishing effect for electron-driven implosions

  5. Mechanical properties and thermal stability of Al–Fe–Ni alloys prepared by centrifugal atomisation and hot extrusion

    International Nuclear Information System (INIS)

    Průša, F.; Vojtěch, D.; Michalcová, A.; Marek, I.

    2014-01-01

    In this work, Al–12Fe and Al–7Fe–5Ni (wt%) alloys prepared by a novel technique including centrifugal atomisation and hot extrusion were studied. The microstructures were investigated using light microscopy, electron scanning microscopy, transmission electron microscopy and X-ray diffraction. The mechanical properties were determined by Vickers hardness measurements and compressive stress–strain tests. To study the thermal stability, the mechanical properties were also measured after 100 h of annealing at 300 °C and 400 °C. In addition, creep tests at a stress of 120 MPa and a temperature of 300 °C were performed. The investigated materials were composed of fine-grained α-Al and intermetallic phases identified as Al 13 Fe 4 and Al 9 FeNi. The Vickers hardness and compressive yield strength were 68 HV5 and 183 MPa, respectively, for the Al–12Fe alloy and 73 HV5 and 226 MPa, respectively, for the Al–7Fe–5Ni alloy. After long-term annealing, the change in the mechanical properties was negligible, indicating the excellent thermal stability of both materials. The creep tests confirmed the highest thermal stability of the Al–7Fe–5Ni alloy with a total compressive creep strain of 15%. The “thermally stable” casting Al–12Si–1Cu–1Mg–1Ni alloy treated by the T6 regime was used as a reference material. The casting alloy exhibited sufficient mechanical properties (hardness and compressive yield strength) at room temperature. However, annealing remarkably softened and reduced its compressive yield strength to almost 50% of the initial values. Additionally, the total creep strain of the casting reference material was almost three times higher than that of the Al–7Fe–5Ni alloy. It has been proven that centrifugally atomised materials quickly compacted via hot extrusion can compete or even exceed the properties of common casting aluminium alloys that are used in automotive industry

  6. Property comparisons of commercially available silica-based microporous insulations I. Machinability and thermal dimensional stability

    International Nuclear Information System (INIS)

    Kramer, Daniel P.; McNeil, Dennis C.; Ruhkamp, Joseph D.; Wells, Donna J.; Stringer, Robert L.; Howell, Edwin I.

    2002-01-01

    Maximizing the thermal to electrical conversion efficiency of a nuclear space power system requires that all of the available thermal energy be utilized in the most efficient manner. Microporous insulations are attractive for application in space power systems due to their very low thermal conductivity. Over the last few years, several new silica-based microporous insulating materials have become commercially available. Property comparisons of the various insulations obtained from company literature and experiments on microporous sample specimens are discussed. The results demonstrate that their machinability and thermal dimensional stability as a function of time at temperature and atmosphere are dependent on the particular material

  7. Carbon nanotube-copper exhibiting metal-like thermal conductivity and silicon-like thermal expansion for efficient cooling of electronics.

    Science.gov (United States)

    Subramaniam, Chandramouli; Yasuda, Yuzuri; Takeya, Satoshi; Ata, Seisuke; Nishizawa, Ayumi; Futaba, Don; Yamada, Takeo; Hata, Kenji

    2014-03-07

    Increasing functional complexity and dimensional compactness of electronic devices have led to progressively higher power dissipation, mainly in the form of heat. Overheating of semiconductor-based electronics has been the primary reason for their failure. Such failures originate at the interface of the heat sink (commonly Cu and Al) and the substrate (silicon) due to the large mismatch in thermal expansion coefficients (∼300%) of metals and silicon. Therefore, the effective cooling of such electronics demands a material with both high thermal conductivity and a similar coefficient of thermal expansion (CTE) to silicon. Addressing this demand, we have developed a carbon nanotube-copper (CNT-Cu) composite with high metallic thermal conductivity (395 W m(-1) K(-1)) and a low, silicon-like CTE (5.0 ppm K(-1)). The thermal conductivity was identical to that of Cu (400 W m(-1) K(-1)) and higher than those of most metals (Ti, Al, Au). Importantly, the CTE mismatch between CNT-Cu and silicon was only ∼10%, meaning an excellent compatibility. The seamless integration of CNTs and Cu was achieved through a unique two-stage electrodeposition approach to create an extensive and continuous interface between the Cu and CNTs. This allowed for thermal contributions from both Cu and CNTs, resulting in high thermal conductivity. Simultaneously, the high volume fraction of CNTs balanced the thermal expansion of Cu, accounting for the low CTE of the CNT-Cu composite. The experimental observations were in good quantitative concurrence with the theoretically described 'matrix-bubble' model. Further, we demonstrated identical in-situ thermal strain behaviour of the CNT-Cu composite to Si-based dielectrics, thereby generating the least interfacial thermal strain. This unique combination of properties places CNT-Cu as an isolated spot in an Ashby map of thermal conductivity and CTE. Finally, the CNT-Cu composite exhibited the greatest stability to temperature as indicated by its low

  8. Thermal stability of nanocrystalline ε-Fe2O3

    Czech Academy of Sciences Publication Activity Database

    Brázda, Petr; Večerníková, Eva; Pližingrová, Eva; Lančok, Adriana; Nižňanský, D.

    2014-01-01

    Roč. 117, č. 1 (2014), s. 85-91 ISSN 1388-6150 R&D Projects: GA ČR GAP204/10/0035 Institutional support: RVO:61388980 Keywords : ε-Fe2O3 * Differential thermal analysis * Evolved gas analysis * Infrared spectroscopy * Thermogravimetry * X-ray powder diffraction Subject RIV: CA - Inorganic Chemistry Impact factor: 2.042, year: 2014

  9. Thermal stability in a newly designed columnar-conical fluidized bed for combustion of rice husk

    Energy Technology Data Exchange (ETDEWEB)

    Rozainee, M.; Salema, A.A.; Ngo, S.P.; Chye, G.B. [Malaysian Technological Univ., Johor Bahru (Malaysia). Dept. of Chemical Engineering

    2006-07-01

    The effects of fluidizing and liquid propane gas (LPG) flow rates on thermal stability of a fluidized bed were examined. The aim of the study was to hybridize a columnar and conical fluidized bed (CCFB) in order to encourage the combustion of low-calorific fuels such as rice husks. Experiments were conducted to examine the thermal stability of the CCFB. Premixed primary air and liquid propane gas (LPG) was fed into the bed in order to verify its thermal stability. Temperature profiles of the combustor and bed were measured. The impact of the fluidizing velocity and LPG flow rate on the temperature profile was examined in order to analyze the influence of the fluidizing velocity and LPG rate on combustion rates. Results of the study showed that the combustion of the CCFB was sustained at a fluidizing velocity of 1.5 U{sub mf} and at an LPG flow rate of 8 liters per minute. Results of the study showed that fluidizing velocity played an important role on the thermal stability of the bed. It was concluded that the thermal stability of the combustor is sufficient for the CCFB. 13 refs., 2 tabs., 5 figs.

  10. Thermal stability of butter oils produced from sheep’s non-pasteurized and pasteurized milk

    Directory of Open Access Journals (Sweden)

    FLAVIA POP

    Full Text Available The physical and chemical characteristics and thermal stability of butter oil produced from non-pasteurized and pasteurized sheep’s milk were studied. Thermal stability of samples was estimated by using the accelerated shelf-life testing method. Samples were stored at 50, 60 and 70oC in the dark and the reaction was monitored by measuring peroxide, thiobarbituric acid and free fatty acid values. The peroxide and thiobarbituric acid values increased as the temperature increased. The increase of acid values of the two samples was not significant. A slight increase in free fatty acid value showed that hydrolytic reactions were not responsible for the deterioration of butter oil samples in thermal stability studies. When compared, butter oil produced from pasteurized sheep’s milk has higher thermal stability than butter oil produced from non-pasteurized sheep’s milk. Although butter oil produced from non-pasteurized milk was not exposed to any heat treatment, the shelf-life of this product was lower than the shelf-life of butter oil produced from pasteurized sheep’s milk. Therefore, heat treatment for pasteurization did not affect the thermal stability of butter oil.

  11. The Thermal Stabilization of Vaccines Against Agents of Bioterrorism

    Science.gov (United States)

    2005-09-01

    intramuscular administration of an adenovirusbased vaccine encoding humanized protective antigen. Hum Gene Ther 14(17): 1673-1682. 7. Abrami L, Lindsay M...1-106) against valley fever was synthesized and purified by scientists at the Southern Arizona Veterans Administrations Medical Center. The reverse...storage stability, more like the original constructs. 60 The chimeric valley fever protein was encapsulated into nanoparticles in an effort to improve

  12. Comparative evaluation of thermal decomposition behavior and thermal stability of powdered ammonium nitrate under different atmosphere conditions.

    Science.gov (United States)

    Yang, Man; Chen, Xianfeng; Wang, Yujie; Yuan, Bihe; Niu, Yi; Zhang, Ying; Liao, Ruoyu; Zhang, Zumin

    2017-09-05

    In order to analyze the thermal decomposition characteristics of ammonium nitrate (AN), its thermal behavior and stability under different conditions are studied, including different atmospheres, heating rates and gas flow rates. The evolved decomposition gases of AN in air and nitrogen are analyzed with a quadrupole mass spectrometer. Thermal stability of AN at different heating rates and gas flow rates are studied by differential scanning calorimetry, thermogravimetric analysis, paired comparison method and safety parameter evaluation. Experimental results show that the major evolved decomposition gases in air are H 2 O, NH 3 , N 2 O, NO, NO 2 and HNO 3 , while in nitrogen, H 2 O, NH 3 , NO and HNO 3 are major components. Compared with nitrogen atmosphere, lower initial and end temperatures, higher heat flux and broader reaction temperature range are obtained in air. Meanwhile, higher air gas flow rate tends to achieve lower reaction temperature and to reduce thermal stability of AN. Self-accelerating decomposition temperature of AN in air is much lower than that in nitrogen. It is considered that thermostability of AN is influenced by atmosphere, heating rate and gas flow rate, thus changes of boundary conditions will influence its thermostability, which is helpful to its safe production, storage, transportation and utilization. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Thermal stability relationships between PMR-15 resin and its composites

    Science.gov (United States)

    Bowles, Kenneth J.; Jayne, Douglas; Leonhardt, Todd A.; Bors, Dennis

    1993-01-01

    A study was conducted to investigate the relationship between the thermo-oxidative stability of PMR-15 matrix resin and the stability of graphite-fiber-reinforced composites that contain this resin as the matrix material. Three areas were investigated. The first was the effect of fiber/matrix interfacial bond strength on the isothermal aging weight loss of composites. By using type-A graphite fibers produced by Hercules, it was possible to study composites reinforced with fibers that were processed to receive different surface treatments. One of the fibers was untreated, a second fiber was treated by oxidation to enhance fiber/matrix bonding, and the third type of fiber was coated with an epoxy sizing. These treatments produced three significantly different interfacial bond strengths. The epoxy sizing on the third fiber was quickly oxidized from the bare fiber surfaces at 288, 316, and 343 C. The weight loss due to the removal of the sizing was constant at 1.5 percent. This initial weight loss was not observed in thermo-oxidative stability studies of composites. The PMR-15 matrix satisfactorily protected the reinforcemnt at all three temperatures.

  14. Influence of surface modified nanoilmenite/amorphous silica composite particles on the thermal stability of cold galvanizing coating

    Directory of Open Access Journals (Sweden)

    A.M. Al-Sabagh

    2018-03-01

    Full Text Available The present approach investigates the use of novel nanoilmenite/amorphous silica composite (NI/AS particles fabricated from ilmenite nanoparticles (FeTiO3 NPs and synthesized amorphous silica grains to improve thermal stability of the cold galvanizing coating. Transmission electron microscopic (TEM images demonstrated that both nanoilmenite and nanocomposite particles were of flaky-like nature and the average diameter of the particles is 20 nm. The lamellar shape of the nanocomposite and spherical nature of Zn-dust particles were illustrated by scanning electron microscopy (SEM micrographs. Different alkyd-based cold galvanizing coating formulations were modified using uniformly dispersing various amounts of the processed nanocomposite particles as a modifier to form some engineering nanocomposite coatings. Thermal stability of the nanocomposite and Zn-dust particles was determined by thermo-gravimetric analysis (TGA. From the obtained results it could be observed that the weight loss (% as a feature of the thermal stability in case of the nanocomposite particles was 2.9 compared to 85.9 for Zn-dust powder grains. Derivative thermo-gravimetric (DTG measurements were done under nitrogen atmosphere for the cured cold galvanizing coating samples heated from room temperature to 1000 °C. The obtained results revealed that the maximum decomposition temperature point in the third degradation step for 6% nanocomposite surface modified cured sample (CG-F was detected at 693 °C and was less value for unmodified conventional cold galvanizing coating (CG-A at 612 °C. The increase in thermal stability with increasing the concentration of nanocomposite particles could be mainly attributed to the interface surface interaction between the nanocomposite particles and alkyd resin matrix in which enhancing the inorganic-organic network stiffness by causing a reduction in the total free spaces and enhancement in the cross-linking density of the cured film

  15. Non-thermal plasma mills bacteria: Scanning electron microscopy observations

    International Nuclear Information System (INIS)

    Lunov, O.; Churpita, O.; Zablotskii, V.; Jäger, A.; Dejneka, A.; Deyneka, I. G.; Meshkovskii, I. K.; Syková, E.; Kubinová, Š.

    2015-01-01

    Non-thermal plasmas hold great promise for a variety of biomedical applications. To ensure safe clinical application of plasma, a rigorous analysis of plasma-induced effects on cell functions is required. Yet mechanisms of bacteria deactivation by non-thermal plasma remain largely unknown. We therefore analyzed the influence of low-temperature atmospheric plasma on Gram-positive and Gram-negative bacteria. Using scanning electron microscopy, we demonstrate that both Gram-positive and Gram-negative bacteria strains in a minute were completely destroyed by helium plasma. In contrast, mesenchymal stem cells (MSCs) were not affected by the same treatment. Furthermore, histopathological analysis of hematoxylin and eosin–stained rat skin sections from plasma–treated animals did not reveal any abnormalities in comparison to control ones. We discuss possible physical mechanisms leading to the shred of bacteria under non-thermal plasma irradiation. Our findings disclose how helium plasma destroys bacteria and demonstrates the safe use of plasma treatment for MSCs and skin cells, highlighting the favorability of plasma applications for chronic wound therapy

  16. The relationship between fatty acid compositions and thermal stability of extra virgin olive oils

    Directory of Open Access Journals (Sweden)

    Fayegh Moulodi

    2014-11-01

    Full Text Available Background: Fatty acids are one of the most important compounds in edible oils. Further, the stability of oils depends on the composition of fatty acids. So, this study was conducted to investigate the effect of fatty acid composition on the oxidative stability of extra virgin olive oils during the heating process. Methods: In total, eight samples of extra virgin olive oil were studied. To evaluate their thermal stability, the oils were heated at 120 ° C for 4 h and sampling was carried out in 2-hour intervals. Then, fatty acid composition, peroxide value, anisidine value and totox value were evaluated according to Iranian national standards. Results: Results showed a significantly direct correlation between Palmitoleic acid and Totox index in the second (r=0.786 and fourth hours (r=0.762, and between linoleic and Totox index in the second (r=0.643 and fourth hours (r=0.786. However, there was a significantly inverse relationship between oleic acid and Totox index in the fourth hour (r=-0.833. Conclusion: Result indicated that linoleic and Palmitoleic acids had a reducing effect on thermal stability of extra virgin olive oil after the second hour. But, Oleic acid caused a positive effect on thermal stability after the fourth hour. Thus, it is concluded that unsaturated fatty acids especially oleic acid affect the thermal stability at final hours.

  17. Preparation and performance of lipophilic α-zirconium phosphate with high thermal stability and its application in thermal-plastic polymers

    Directory of Open Access Journals (Sweden)

    Ya Du

    2015-10-01

    Full Text Available To prepare lipophilic α-zirconium phosphate with high grafting ratio and thermal stability (OZrP-HT and explore its potential application in thermal-plastic polymers, a novel method was developed by surface lipophilicity enhancement strategy. The commercial α-zirconium phosphate (α-ZrP was pre-intercalated by n-propylamine (PA and grafted by silane coupling agents. Then the pre-intercalated PA was removed by heat-treatment, and the obtained OZrP-HT was utilized to fabricate the phosphorous-containing polyester (P-co-PET/OZrP-HT nanocomposites by melt-blending method. The prepared OZrP-HT and P-co-PET/OZrP-HT nanocomposites were characterized by Wide Angle X-ray Diffraction (WAXD, Fourier Transform Infrared Spectroscopy (FTIR, Thermogravimetric Analysis (TGA, Transmission Electron Microscope (TEM, etc. The results show that OZrP-HT with high grafting ratio (13.78 wt% and thermal stability (Tonset=368 °C was successfully prepared via this novel method and was uniformly intercalated by P-co-PET molecular chains. OZrP-HT had no significant effect on the fiber processability of P-co-PET polymer, and flame retardant properties of (P-co-PET/OZrP-HT nanocomposites were improved. This method may be suitable for organic modification of general inorganic layered compounds and could extend the potential applications in thermo-plastic polymers.

  18. Stability, rheology and thermal analysis of functionalized alumina- thermal oil-based nanofluids for advanced cooling systems

    International Nuclear Information System (INIS)

    Ilyas, Suhaib Umer; Pendyala, Rajashekhar; Narahari, Marneni; Susin, Lim

    2017-01-01

    Highlights: • Alumina nanoparticles are functionalized with oleic acid. • Functionalization of alumina nanoparticles gives better dispersion in thermal oil. • Thermophysical properties of nanofluids are experimentally measured. • TGA confirms the improvement in life of nanofluids. - Abstract: Thermal oils are widely used as cooling media in heat transfer processes. However, their potential has not been utilised exquisitely in many applications due to low thermal properties. Thermal oil-based nanofluids are prepared by dispersing functionalized alumina with varying concentrations of 0.5–3 wt.% to enhance thermal properties of oil for advanced cooling systems. The oleic acid coated alumina is prepared and then dispersed in the oil to overcome the aggregation of nanoparticles in base fluid. The surface characterizations of functionalized nanoparticles are performed using different analysis such as XRD, EDS, SEM, TEM and FTIR. Dispersion behaviour and agglomeration studies are conducted at natural and functionalized conditions using different analysis to ensure long-term stability of nanofluids. In addition, rheological behaviour of non-Newtonian nanofluids is studied at high shear rates (100–2000 s"−"1). Effective densities and enhancement in thermal conductivities are measured for different nanofluids concentrations. Specific heat capacity is measured using Differential Scanning Calorimetry. The correlations are developed for thermophysical properties of nanofluids. Thermogravimetric analysis is performed with respect to temperature and time to exploit the effect of the addition of nanoparticles on the degradation of nanofluids. Significant improvement in the thermal properties of oil is observed using highly stable functionalized alumina nano-additives.

  19. Cu-Ag core–shell nanoparticles with enhanced oxidation stability for printed electronics

    International Nuclear Information System (INIS)

    Lee, Changsoo; Kim, Na Rae; Koo, Jahyun; Lee, Yung Jong; Lee, Hyuck Mo

    2015-01-01

    In this work, we synthesized uniform Cu–Ag core–shell nanoparticles using a facile two-step process that consists of thermal decomposition and galvanic displacement methods. The core–shell structure of these nanoparticles was confirmed through characterization using transmission electron microscopy, energy-dispersive spectroscopy, and x-ray diffraction. Furthermore, we investigated the oxidation stability of the Cu–Ag core–shell nanoparticles in detail. Both qualitative and quantitative x-ray photoelectron spectroscopy analyses confirm that the Cu–Ag core–shell nanoparticles have considerably higher oxidation stability than Cu nanoparticles. Finally, we formulated a conductive ink using the synthesized nanoparticles and coated it onto glass substrates. Following the sintering process, we compared the resistivity of the Cu–Ag core–shell nanoparticles with that of the Cu nanoparticles. The results of this study clearly show that the Cu–Ag core–shell nanoparticles can potentially be used as an alternative to Ag nanoparticles because of their superior oxidation stability and electrical properties. (paper)

  20. Thermal stability of gold-PS nanocomposites thin films

    Indian Academy of Sciences (India)

    Low-temperature transmission electron microscopy (TEM) studies were performed on polystyrene (PS, w = 234 K) – Au nanoparticle composite thin films that were annealed up to 350°C under reduced pressure conditions. The composite thin films were prepared by wet chemical approach and the samples were then ...

  1. Thermal stability of gold-PS nanocomposites thin films

    Indian Academy of Sciences (India)

    Administrator

    be more effective at modifying properties, specifically such as the electronic and .... embedded inside will become more mobile leading to coalescence of these particles ... particle in a polymer matrix with a d spacing of. 0⋅235 ± 0⋅005 nm ...

  2. Preparation and characterizations of HDPE-EVA alloy/OMT nanocomposites/paraffin compounds as a shape stabilized phase change thermal energy storage material

    International Nuclear Information System (INIS)

    Cai Yibing; Hu Yuan; Song Lei; Lu Hongdian; Chen Zuyao; Fan Weicheng

    2006-01-01

    A kind of shape stabilized phase change nanocomposites materials (PCNM) based on high density polyethylene (HDPE)/ethylene-vinyl acetate (EVA) alloy, organophilic montmorillonite (OMT), paraffin and intumescent flame retardant (IFR) are prepared using twin-screw extruder technique. The structures of the HDPE-EVA alloy/OMT nanocomposites are evidenced by the X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that an ordered intercalated nanomorphology of the HDPE-EVA alloy/OMT nanocomposites is formed. Then the structures of the shape stabilized PCNM are characterized by scanning electron microscopy (SEM). The HDPE-EVA alloy/OMT nanocomposites act as the supporting material and form the three-dimensional network structure. The paraffin acts as a phase change material and disperses in the three-dimensional network structure. Its latent heat is given by differential scanning calorimeter (DSC) method. The SEM and DSC results show that the additives of IFR have little effect on the network structure and the latent heat of shape stabilized PCNM, respectively. The thermal stability properties are characterized by thermogravimetric analysis (TGA). The TGA analysis results indicate that the flame retardant shape stabilized PCNM produce a larger amount of char residue at 800 deg. C than that of shape stabilized PCNM, although the onset of weight loss of the flame retardant shape stabilized PCNM occur at a lower temperature. The formed multicellular char residue contributes to the improvement of thermal stability performance. The probable combustion mechanisms are also discussed in this paper

  3. Thermal Stabilization of Cryogenic System in Superconducting Cyclotron

    International Nuclear Information System (INIS)

    Shin, Seung Jae; Kim, Kyung Min; Cho, Hyung Hee; Hong, Bong Hwan; Kang, Joon Sun; Ahn, Dong Hyun

    2011-01-01

    Radiology has some useful applications for medical purpose. For cancer therapy, the superconducting cyclotron should generate heavy ion beams. It radiates heavy ion beams to cancer patients. In order to make cyclotron system stable, the cryogenic system which makes superconducting state should work constantly. However, radiation heat transfer of cryogenic system should be considered because liquid helium's boiling point is extremely low and there is huge temperature difference between the cryogenic system and ambient temperature. Accordingly, thermal analysis should be carried out. In this paper, the numerical analysis of the cryogenic system in practical superconducting cyclotron show temperature distribution and suggest the number of coolers using ANSYS Workbench program

  4. High-temperature stability of yttria-stabilized zirconia thermal barrier ...

    Indian Academy of Sciences (India)

    temperature drop was found to increase with the coating thickness of YSZ. The coatings ... thermal barrier coating system on niobium alloys for supersonic vehicles. .... Voltage (V). 75 ..... However, distribution of the other elements; such as Ni,.

  5. Effect of Microstructure on the Thermal Conductivity of Plasma Sprayed Y2O3 Stabilized Zirconia (8% YSZ

    Directory of Open Access Journals (Sweden)

    Ningning Hu

    2017-11-01

    Full Text Available In this paper, the effect of microstructure on the thermal conductivity of plasma-sprayed Y2O3 stabilized ZrO2 (YSZ thermal barrier coatings (TBCs is investigated. Nine freestanding samples deposited on aluminum alloys are studied. Cross-section morphology such as pores, cracks, m-phase content, grain boundary density of the coated samples are examined by scanning electron microscopy (SEM and electron back-scattered diffraction (EBSD. Multiple linear regressions are used to develop quantitative models that describe the relationship between the particle parameters, m-phase content and features of the microstructure such as porosity, crack-porosity, and the length density of small and big angle-cracks. Moreover, the relationship between the microstructure and thermal conductivity is investigated. Results reveal that the thermal conductivity of the coating is mainly determined by the microstructure and grain boundary density at room temperature (25 °C, and by the length density of big-angle-crack, monoclinic phase content and grain boundary density at high temperature (1200 °C.

  6. On the Boltzmann Equation of Thermal Transport for Interacting Phonons and Electrons

    Directory of Open Access Journals (Sweden)

    Amelia Carolina Sparavigna

    2016-05-01

    Full Text Available The thermal transport in a solid can be determined by means of the Boltzmann equations regarding its distributions of phonons and electrons, when the solid is subjected to a thermal gradient. After solving the coupled equations, the related thermal conductivities can be obtained. Here we show how to determine the coupled equations for phonons and electrons.

  7. Advanced kinetics for calorimetric techniques and thermal stability screening of sulfide minerals

    International Nuclear Information System (INIS)

    Iliyas, Abduljelil; Hawboldt, Kelly; Khan, Faisal

    2010-01-01

    Thermal methods of analysis such as differential scanning calorimetry (DSC) provide a powerful methodology for the study of solid reactions. This paper proposes an improved thermal analysis methodology for thermal stability investigation of complex solid-state reactions. The proposed methodology is based on differential iso-conversional approach and involves peak separation, individual peak analysis and combination of isothermal/non-isothermal DSC measurements for kinetic analysis and prediction. The proposed thermal analysis, which coupled with Mineral Libration Analyzer (MLA) technique was employed to investigate thermal behavior of sulfide mineral oxidation. The importance of various experimental variables such as particle size, heating rate and atmosphere were investigated and discussed. The information gained from such an advanced thermal analysis method is useful for scale-up processes with potential of significant savings in plant operations, as well as in mitigating adverse environmental and safety issues arising from handling and storage of sulfide minerals.

  8. Nonlinear features of the electron temperature gradient mode and electron thermal transport in tokamaks

    International Nuclear Information System (INIS)

    Kaw, P.K.; Singh, R.; Weiland, J.G.

    2001-01-01

    Analytical investigations of several linear and nonlinear features of ETG turbulence are reported. The linear theory includes effects such as finite beta induced electromagnetic shielding, coupling to electron magnetohydrodynamic modes like whistlers etc. It is argued that nonlinearly, turbulence and transport are dominated by radially extended modes called 'streamers'. A nonlinear mechanism generating streamers based on a modulational instability theory of the ETG turbulence is also presented. The saturation levels of the streamers using a Kelvin Helmholtz secondary instability mechanism are calculated and levels of the electron thermal transport due to streamers are estimated. (author)

  9. Thermal stability and primary phase of Al-Ni(Cu)-La amorphous alloys

    International Nuclear Information System (INIS)

    Huang Zhenghua; Li Jinfu; Rao Qunli; Zhou Youhe

    2008-01-01

    Thermal stability and primary phase of Al 85+x Ni 9-x La 6 (x = 0-6) and Al 85 Ni 9-x Cu x La 6 (x = 0-9) amorphous alloys were investigated by X-ray diffraction and differential scanning calorimeter. It is revealed that replacing Ni in the Al 85 Ni 9 La 6 alloy by Cu decreases the thermal stability and makes the primary phase change from intermetallic compounds to single fcc-Al as the Cu content reaches and exceeds 4 at.%. When the Ni and La contents are fixed, replacing Al by Cu increases the thermal stability but also promotes the precipitation of single fcc-Al as the primary phase

  10. Thermal stability of the krypton Hall effect thruster

    Directory of Open Access Journals (Sweden)

    Szelecka Agnieszka

    2017-03-01

    Full Text Available The Krypton Large IMpulse Thruster (KLIMT ESA/PECS project, which has been implemented in the Institute of Plasma Physics and Laser Microfusion (IPPLM and now is approaching its final phase, was aimed at incremental development of a ~500 W class Hall effect thruster (HET. Xenon, predominantly used as a propellant in the state-of-the-art HETs, is extremely expensive. Krypton has been considered as a cheaper alternative since more than fifteen years; however, to the best knowledge of the authors, there has not been a HET model especially designed for this noble gas. To address this issue, KLIMT has been geared towards operation primarily with krypton. During the project, three subsequent prototype versions of the thruster were designed, manufactured and tested, aimed at gradual improvement of each next exemplar. In the current paper, the heat loads in new engine have been discussed. It has been shown that thermal equilibrium of the thruster is gained within the safety limits of the materials used. Extensive testing with both gases was performed to compare KLIMT’s thermal behaviour when supplied with krypton and xenon propellants.

  11. Thermal stability of the C106 dye in robust electrolytes

    DEFF Research Database (Denmark)

    Lund, Torben; Phuong, Nguyen Tuyet; Pechy, Peter

    -MPN) introduced by Gao et al. in 2008. [1]. Figure 1 Thermal degradation of C106 bound to TiO2 at 80 ºC in dark as a function of heating time. ● C106 = RuLL´(NCS)2 ■ RuLL´(NCS)(NBB)+ ▲ RuLL´(NCS)(3-MPN)+ The C106 dye was attached to the surface of TiO2 nano-particles and stable colloidal solutions...... of the particles were prepared in electrolyte mixture B. The solutions were thermally treated at 80 ◦C for 0-2000 hours followed by dye extraction and analysis by HPLC coupled to UV/Vis and electro spray mass spectrometry [2]. Figure 1 shows the concentration profiles of C106 samples prepared under ambient...... and glove box conditions as a function of the heating time. Preparation of the samples under strict atmospheric moisture control in a glove box gives the best results with a steady state surface concentration of 80% intact C106 and 20% NBB substitution product after ~1500 hours of heating at 80 ºC. If dye...

  12. Surface modification of montmorillonite on surface Acid-base characteristics of clay and thermal stability of epoxy/clay nanocomposites.

    Science.gov (United States)

    Park, Soo-Jin; Seo, Dong-Il; Lee, Jae-Rock

    2002-07-01

    In this work, the effect of surface treatments on smectitic clay was investigated in surface energetics and thermal behaviors of epoxy/clay nanocomposites. The pH values, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) were used to analyze the effect of cation exchange on clay surface and the exfoliation phenomenon of clay interlayer. The surface energetics of clay and thermal properties of epoxy/clay nanocomposites were investigated in contact angles and thermogravimetric analysis (TGA), respectively. From the experimental results, the surface modification of clay by dodecylammonium chloride led to the increases in both distance between silicate layers of about 8 A and surface acid values, as well as in the electron acceptor component (gamma(+)(s)) of surface free energy, resulting in improved interfacial adhesion between basic (or electron donor) epoxy resins and acidic (electron acceptor) clay interlayers. Also, the thermal stability of nanocomposites was highly superior to pure epoxy resin due to the presence of the well-dispersed clay nanolayer, which has a barrier property in a composite system.

  13. Characterization of phycocyanin from Spirulina fusiformis and its thermal stability

    Science.gov (United States)

    Munawaroh, H. S. H.; Darojatun, K.; Gumilar, G. G.; Aisyah, S.; Wulandari, A. P.

    2018-05-01

    Microalgae have some pigments which are potential to be used as functional colorant for foods and cosmetics industries. Here, Spirulina fusiformis is one of the major sources of a blue pigment phycocyanin which has commercial and biotechnological value for biomedical research, as well as a natural colorant for food and cosmetic industries. This study aims at investigating the characteristic of isolated C-phycocyanin from Spirulina fusiformis and its stability under different temperature. A food grade phycocyanin with purity of 2.0 (A620/A280) was obtained successfully from Spirulina fusiformis cultured in seawater-based modified medium and purified by ammonium sulfate precipitation. No significant changes were observed in the spectrum absorbance of C-phycocyanin at temperature up to 60°C over 30 minutes of incubation, and was observed to significantly denaturation at 70°C and higher temperature. Incubation of the pigment at relatively high temperature resulted in a decrease in the spectrum intensities of the C-phycocyanin in a temperature-dependent manner. Taken together, our results suggest that the optimal condition for preserving the stability of food grade phycocyanin isolated from Spirulina fusiformis is taking it at low temperature.

  14. The influence of polyol type on cell geometry and the thermal stability of polyurethane foams

    Directory of Open Access Journals (Sweden)

    Prendžov Slobodan J.

    2006-01-01

    Full Text Available The aim of this study was to examine the influence of substituting defined amounts of polyol Voranol 3322 by polyol Voranol CP 1055 on the cell geometry and thermal stability of the synthesized flexible polyurethane foams. The influence of the amount of antipyrene on the cell geometry and their thermal stability was also investigated. The following components were used in the synthesis of the polyurethanes: a mixture of two polyols (Voranol 3322 with the hydroxyl number 47 mg KOH/g, mean molecular mass 3400 and Voranol CP 1055 with the hydroxyl number 156 mg KOH/g, mean molecular mass 1000, toluene discarnate as the isocyanate component, a combination of an organic-metallic compound and a tertiary amine as catalysts, surfactant and water as the coreactant. The thermal stability was determined by thermogravimetric analysis (in a nitrogen atmosphere. The cell geometry was analyzed by optical microscopy. Examination of the cell geometry revealed different cell shapes. The form factor as an indicator of cell deviation from spherical shape increased (more round forms were observed with increasing amount of Voranol CP 1055. The TG examination showed that specimens with 6 and 8 g of Voranol 3322 substituted by Voranol CP 1055 completely degraded at 350 °C, while foams with 10 and 12 g of Voranol 3322 substituted by Voranol CP 1055 displayed lower mass loss at higher temperatures and had residual masses of 46 % and 43 % at 600°C respectively. The addition of antipyrene in an amount of 1% (based on the amount of polyol contributed to improved thermal stability, no visible color change of the specimen tested at 210°C for 40 minutes, and to rounder cell forms. Considering the obtained results it can be concluded that an increase in the amount of Voranol CP 1055 yielded more spherically shaped cells and better thermal stability of the synthesized flexible polyurethane foams. The addition of antipyrene improves the thermal stability and the cell geometry.

  15. Evaluation of electronic stability control effectiveness in Australasia.

    Science.gov (United States)

    Scully, Jim; Newstead, Stuart

    2008-11-01

    Electronic stability control (ESC) is an in-vehicle technology aimed at improving primary safety by assisting the driver in avoiding loss of control of the vehicle. The aim of this study was to use available crash data from Australia and New Zealand to evaluate the effectiveness of ESC in reducing crash risk and to establish whether benefits estimated from overseas studies have translated to the Australian and New Zealand environments. The sample analysed included 7699 crashed vehicles fitted with ESC which comprised of 90 different models. Poisson regression was used to test whether the differences in the observed and expected crash counts for ESC fitted vehicles were significant, with exposure being induced from counts of rear end impacts. It was found that ESC reduced the risk of single vehicle crashes in which the driver was injured by 68% for 4WDs compared with 27% for passenger cars. The effect of ESC on multiple vehicle crashes in Australia and New Zealand was not clear. The long-term benefits of fitting ESC to all vehicles in Australia were also investigated based on the estimated single vehicle crash reductions.

  16. Is electronic stability program effective on French roads?

    Science.gov (United States)

    Page, Yves; Cuny, Sophie

    2006-03-01

    This paper proposes an evaluation of the effectiveness of the electronic stability program (ESP) in terms of reduction of injury accidents in France. The method consists of 3 steps: The identification, in the French National injury accident census, of accident-involved cars for which the determination of whether or not the car was fitted with ESP is possible. A sampler of 136 cars involved in injury accidents occurred in 2000, 2001, 2002 and 2003 was then selected. But we had to restrict the analysis to only 588 Renalut Laguna's. The identification of accident situations for which we can determine whether or not ESP is pertinent ( for example ESP is pertinent for loss of control accidents whilst it is not for cars pulling out of a junction). The calculation, via a logistic regression, of the relative risk of being involved in an ESP-pertinent accident for ESP equipped cars versus unequipped cars, divided by the relative risk of being involved in a non-ESP-pertinent accident for ESP equipped cars versus unequipped cars. This relative risk is assumed to be the best estimator of ESP effectiveness. The arguments for such a method, effectiveness indicator and implicit hypothesis are presented and discussed in the paper. Based on a few assumptions, ESP is proved to be likely effective. Currently, the relative risk of being involved in an ESP-pertinent accident for ESP-equipped cars is lower (-44%, although not statistically significant) than for other cars.

  17. Car drivers' perceptions of electronic stability control (ESC) systems.

    Science.gov (United States)

    Vadeby, Anna; Wiklund, Mats; Forward, Sonja

    2011-05-01

    As a way to reduce the number of car crashes different in-car safety devices are being introduced. In this paper one such application is being investigated, namely the electronic stability control system (ESC). The study used a survey method, including 2000 private car drivers (1000 driving a car with ESC and 1000 driving a car without ESC). The main objective was to investigate the effect of ESC on driver behaviour. Results show that drivers report that they drive even more carelessly when they believe that they have ESC, than when they do not. Men are more risk prone than women and young drivers more than older drivers. Using the theory of planned behaviour the results show that attitude, subjective norm and perceived control explain between 62% and 67% of driver's variation of intentions to take risks. When descriptive norm was added to the model a small but statistically significant increase was found. The study also shows that more than 35% erroneously believe that their car is equipped with an ESC system. These findings may suggest that driver behaviour could reduce the positive effect ESC has on accidents. It also shows that drivers who purchase a new car are not well informed about what kind of safety devices the car is equipped with. These findings highlight the need for more targeted information to drivers. Copyright © 2010 Elsevier Ltd. All rights reserved.

  18. High thermal stability solution-processable narrow-band gap molecular semiconductors.

    Science.gov (United States)

    Liu, Xiaofeng; Hsu, Ben B Y; Sun, Yanming; Mai, Cheng-Kang; Heeger, Alan J; Bazan, Guillermo C

    2014-11-19

    A series of narrow-band gap conjugated molecules with specific fluorine substitution patterns has been synthesized in order to study the effect of fluorination on bulk thermal stability. As the number of fluorine substituents on the backbone increase, one finds more thermally robust bulk structures both under inert and ambient conditions as well as an increase in phase transition temperatures in the solid state. When integrated into field-effect transistor devices, the molecule with the highest degree of fluorination shows a hole mobility of 0.15 cm(2)/V·s and a device thermal stability of >300 °C. Generally, the enhancement in thermal robustness of bulk organization and device performance correlates with the level of C-H for C-F substitution. These findings are relevant for the design of molecular semiconductors that can be introduced into optoelectronic devices to be operated under a wide range of conditions.

  19. Thermal stability of hydrogenated small-diameter carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Podlivaev, A. I., E-mail: AIPodlivayev@mephi.ru; Openov, L. A. [National Research Nuclear University “MEPhI” (Russian Federation)

    2017-02-15

    The initial stage of hydrogen desorption from fully hydrogenated carbon nanotubes (3.0) and (2.2) is numerically studied by the molecular dynamics method. The temperature dependence of the desorption rate is directly determined at T = 1800–2500 K. The characteristic desorption times are determined at temperatures outside this range by extrapolation. It is shown that hydrogen desorption leads to the appearance of electronic states in the band gap.

  20. Stability of electron-beam energy monitor for quality assurance of the electron-beam energy from radiotherapy accelerators

    International Nuclear Information System (INIS)

    Chida, Koichi; Zuguchi, Masayuki; Saito, Haruo; Takai, Yoshihiro; Mitsuya, Masatoshi; Sakakida, Hideharu; Yamada, Shogo; Kohzuki, Masahiro

    2002-01-01

    Information on electron energy is important in planning radiation therapy using electrons. The Geske 3405 electron beam energy monitor (Geske monitor, PTW Nuclear Associates, Carle Place, NY, USA) is a device containing nine ionization chambers for checking the energy of the electron beams produced by radiotherapy accelerators. We wondered whether this might increase the likelihood of ionization chamber trouble. In spite of the importance of the stability of such a quality assurance (QA) device, there are no reports on the stability of values measured with a Geske monitor. The purpose of this paper was therefore to describe the stability of a Geske monitor. It was found that the largest coefficient of variation (CV) of the Geske monitor measurements was approximately 0.96% over a 21-week period. In conclusion, the stability of Geske monitor measurements of the energy of electron beams from a linear accelerator was excellent. (author)

  1. The formation of α-phase SnS nanorods by PVP assisted polyol synthesis: Phase stability, micro structure, thermal stability and defects induced energy band transitions

    Energy Technology Data Exchange (ETDEWEB)

    Baby, Benjamin Hudson; Mohan, D. Bharathi, E-mail: d.bharathimohan@gmail.com

    2017-05-01

    We report the formation of single phase of SnS nanostructure through PVP assisted polyol synthesis by varying the source concentration ratio (Sn:S) from 1:1M to 1:12M. The effect of PVP concentration and reaction medium towards the preparation of SnS nanostructure is systematically studied through confocal Raman spectrometer, X-ray diffraction, thermogravimetry analysis, scanning electron microscope, transmission electron microscopy, X-ray photoelectron spectroscopy, UV–Vis–NIR absorption and fluorescence spectrophotometers. The surface morphology of SnS nanostructure changes from nanorods to spherical shape with increasing PVP concentration from 0.15M to 0.5M. Raman analysis corroborates that Raman active modes of different phases of Sn-S are highly active when Raman excitation energy is slightly greater than the energy band gap of the material. The presence of intrinsic defects and large number of grain boundaries resulted in an improved thermal stability of 20 °C during the phase transition of α-SnS. Band gap calculation from tauc plot showed the direct band gap of 1.5 eV which is attributed to the single phase of SnS, could directly meet the requirement of an absorber layer in thin film solar cells. Finally, we proposed an energy band diagram for as synthesized single phase SnS nanostructure based on the experimental results obtained from optical studies showing the energy transitions attributed to band edge transition and also due to the presence of intrinsic defects. - Highlights: • PVP stabilizes the orthorhombic (α) phase of SnS. • Optical band gap of P type SnS tuned by PVP for photovoltaic applications. • The formation of Sn rich SnS phase is investigated through XPS analysis. • Intrinsic defects enhance the thermal stability of α-SnS. • The feasibility of energy transition liable to point defects is discussed.

  2. Local thermal conductivity of polycrystalline AlN ceramics measured by scanning thermal microscopy and complementary scanning electron microscopy techniques

    International Nuclear Information System (INIS)

    Zhang Yue-Fei; Wang Li; Wei Bin; Ji Yuan; Han Xiao-Dong; Zhang Ze; Heiderhoff, R.; Geinzer, A. K.; Balk, L. J.

    2012-01-01

    The local thermal conductivity of polycrystalline aluminum nitride (AlN) ceramics is measured and imaged by using a scanning thermal microscope (SThM) and complementary scanning electron microscope (SEM) based techniques at room temperature. The quantitative thermal conductivity for the AlN sample is gained by using a SThM with a spatial resolution of sub-micrometer scale through using the 3ω method. A thermal conductivity of 308 W/m·K within grains corresponding to that of high-purity single crystal AlN is obtained. The slight differences in thermal conduction between the adjacent grains are found to result from crystallographic misorientations, as demonstrated in the electron backscattered diffraction. A much lower thermal conductivity at the grain boundary is due to impurities and defects enriched in these sites, as indicated by energy dispersive X-ray spectroscopy. (condensed matter: structural, mechanical, and thermal properties)

  3. Stabilizing effects of hot electrons on low frequency plasma drift waves

    International Nuclear Information System (INIS)

    Huang Chaosong; Qiu Lijian; Ren Zhaoxing

    1988-01-01

    The MHD equation is used to study the stabilization of low frequency drift waves driven by density gradient of plasma in a hot electron plasma. The dispersion relation is derived, and the stabilizing effects of hot electrons are discussed. The physical mechanism for hot electron stabilization of the low frequency plasma perturbations is charge uncovering due to the hot electron component, which depends only on α, the ratio of N h /N i , but not on the value of β h . The hot electrons can reduce the growth rate of the interchange mode and drift wave driven by the plasma, and suppress the enomalous plasma transport caused by the drift wave. Without including the effectof β h , the stabilization of the interchange mode requires α≅2%, and the stabilization of the drift wave requires α≅40%. The theoretical analyses predict that the drift wave is the most dangerous low frequency instability in the hot electron plasma

  4. The thermal stability of the Fusarium solani pisi cutinase as a function of pH

    OpenAIRE

    Petersen, Steffen B; Fojan, Peter; Petersen, Evamaria I; Petersen, Maria Teresa Neves

    2001-01-01

    We have investigated the thermal stability of the Fusarium solani pisi cutinase as a function of pH, in the range from pH 2–12. Its highest enzymatic activity coincides with the pH-range at which it displays its highest thermal stability. The unfolding of the enzyme as a function of pH was investigated by microcalorimetry. The ratio between the calorimetric enthalpy (ΔHcal) and the van′t Hoff enthalpy (ΔHv) obtained, is far from unity, indicating that cutinase does not exhibit a simple...

  5. Time and Temperature Test Results for PFP Thermal Stabilization Furnaces

    International Nuclear Information System (INIS)

    COMPTON, J.A.

    2000-01-01

    The national standard for plutonium storage acceptability (standard DOE-STD-3013-99, generally known as ''the 3013 standard'') has been revised to clarify the requirement for processes that will produce acceptable storage materials. The 3013 standard (Reference 1) now states that ''Oxides shall be stabilized by heating the material in an oxidizing atmosphere to a Material Temperature of at least 950 C (1742 F) for not less than 2 hours.'' The process currently in use for producing stable oxides for storage at the Plutonium Finishing Plant (PFP) heats a furnace atmosphere to 1000 C and holds it there for 2 hours. The temperature of the material being stabilized is not measured directly during this process. The Plutonium Process Support Laboratories (PPSL) were requested to demonstrate that the process currently in use at PFP is an acceptable method of producing stable plutonium dioxide consistently. A spare furnace identical to the production furnaces was set up and tested under varying conditions with non-radioactive surrogate materials. Reference 2 was issued to guide the testing program. The process currently in use at the PFP for stabilizing plutonium-bearing powders was shown to heat all the material in the furnace to at least 950 C for at least 2 hours. The current process will work for (1) relatively pure plutonium dioxide, (2) dioxide powders mixed with up to 20 weight percent magnesium oxide, and (3) dioxide powders with up to 11 weight percent magnesium oxide and 20 weight percent magnesium nitrate hexahydrate. Time and temperature data were also consistent with a successful demonstration for a mixture containing 10 weight percent each of sodium and potassium chloride; however, the molten chloride salts destroyed the thermocouples in the powder and temperature data were unavailable for part of that run. These results assume that the current operating limits of no more than 2500 grams per furnace charge and a powder height of no more than 1.5 inches remain

  6. Cu-based shape memory alloys with enhanced thermal stability and mechanical properties

    International Nuclear Information System (INIS)

    Chung, C.Y.; Lam, C.W.H.

    1999-01-01

    Cu-based shape memory alloys were developed in the 1960s. They show excellent thermoelastic martensitic transformation. However the problems in mechanical properties and thermal instability have inhibited them from becoming promising engineering alloys. A new Cu-Zn-Al-Mn-Zr Cu-based shape memory alloy has been developed. With the addition of Mn and Zr, the martensitic transformation behaviour and the grain size ca be better controlled. The new alloys demonstrates good mechanical properties with ultimate tensile strenght and ductility, being 460 MPa and 9%, respectively. Experimental results revealed that the alloy has better thermal stability, i.e. martensite stabilisation is less serious. In ordinary Cu-Zn-Al alloys, martensite stabilisation usually occurs at room temperature. The new alloy shows better thermal stability even at elevated temperature (∝150 C, >A f =80 C). A limited small amount of martensite stabilisation was observed upon ageing of the direct quenched samples as well as the step quenched samples. This implies that the thermal stability of the new alloy is less dependent on the quenching procedure. Furthermore, such minor martensite stabilisation can be removed by subsequent suitable parent phase ageing. The new alloy is ideal for engineering applications because of its better thermal stability and better mechanical properties. (orig.)

  7. [Thermal stability of rhodopsins and opsins in warm- and cold-blooded vertebrates].

    Science.gov (United States)

    Berman, A L; Suvorov, S A; Parnova, R G; Gracheva, O A; Rychkova, M P

    1981-01-01

    Thermal stability of rhodopsins and opsins has been studied in endothermic (sheep, cattle, pig, rat) and ectothermic (frog) animals under two different conditions -- in the intact photoreceptor membranes (PM) and after substitution of the lipid surrounding of rhodopsins by molecules of a detergent Triton X-100. Lipid composition of PM in these animals was also studied, as well as the effect of proteases (pronase and papaine) upon thermal stability of rhodopsins in PM and in 1% Triton X-100 solutions. The thermal resistance of rhodopsins in PM was found to vary in the animals used to a great extent. The maximal differences in thermal stability of rhodopsins in ecto- and endothermic animals were due to the properties of photoreceptor protein itself, whereas in ectothermic animals they resulted mainly from differences in the lipid composition of PM. PM of endothermic animals differ from those of ectothermic ones by a lower content of polyenoic fatty acids and by a higher amount of phosphatidyl ethanolamine. The thermal stability of rhodopsins is not due to rhodopsin molecule as a whole, and depends mainly on its part which is directly bound to 11-cis retinal, located in hydrophobic region of PM and inaccessible to protease attack.

  8. Model Development for MODIS Thermal Band Electronic Crosstalk

    Science.gov (United States)

    Chang, Tiejun; Wu, Aisheng; Geng, Xu; Li, Yonghonh; Brinkman, Jake; Keller, Graziela; Xiong, Xiaoxiong

    2016-01-01

    MODerate-resolution Imaging Spectroradiometer (MODIS) has 36 bands. Among them, 16 thermal emissive bands covering a wavelength range from 3.8 to 14.4 m. After 16 years on-orbit operation, the electronic crosstalk of a few Terra MODIS thermal emissive bands developed substantial issues that cause biases in the EV brightness temperature measurements and surface feature contamination. The crosstalk effects on band 27 with center wavelength at 6.7 m and band 29 at 8.5 m increased significantly in recent years, affecting downstream products such as water vapor and cloud mask. The crosstalk effect is evident in the near-monthly scheduled lunar measurements, from which the crosstalk coefficients can be derived. The development of an alternative approach is very helpful for independent verification.In this work, a physical model was developed to assess the crosstalk impact on calibration as well as in Earth view brightness temperature retrieval. This model was applied to Terra MODIS band 29 empirically to correct the Earth brightness temperature measurements. In the model development, the detectors nonlinear response is considered. The impact of the electronic crosstalk is assessed in two steps. The first step consists of determining the impact on calibration using the on-board blackbody (BB). Due to the detectors nonlinear response and large background signal, both linear and nonlinear coefficients are affected by the crosstalk from sending bands. The second step is to calculate the effects on the Earth view brightness temperature retrieval. The effects include those from affected calibration coefficients and the contamination of Earth view measurements. This model links the measurement bias with crosstalk coefficients, detector non-linearity, and the ratio of Earth measurements between the sending and receiving bands. The correction of the electronic cross talk can be implemented empirically from the processed bias at different brightness temperature. The implementation

  9. Studies on Thermal Oxidation Stability of Aviation Lubricating Oils

    Directory of Open Access Journals (Sweden)

    Wu Nan

    2017-01-01

    Full Text Available Simulating the operating condition of aviation engine via autoclave experiment of high temperature and pressure, we studied the physic-chemical property of poly-α-olefin base oil samples mixed with antioxidants of 2,6-di-tert-butyl-4-methylphenol and p,p’-diisooctyl diphenylamine at different temperature. The mechanism of degradation of PAO aviation lubricating oil was analyzed according to the oxidized products by modern analytical instruments. The results showed that the aviation lubricating oil produced a large number of low molecule compounds while increasing the temperature, and resulted in the viscosity decreasing and acid value increasing which indicated that the thermal oxidation of the oil sample underwent a radical process.

  10. Effects of additives on thermal stability of Li ion cells

    Science.gov (United States)

    Doughty, Daniel H.; Roth, E. Peter; Crafts, Chris C.; Nagasubramanian, G.; Henriksen, Gary; Amine, Khalil

    Li ion cells are being developed for high-power applications in hybrid electric vehicles, because these cells offer superior combination of power and energy density over current cell chemistries. Cells using this chemistry are proposed for battery systems in both internal combustion engine and fuel cell-powered hybrid electric vehicles. However, the safety of these cells needs to be understood and improved for eventual widespread commercial applications. The thermal-abuse response of Li ion cells has been improved by the incorporation of more stable anode carbons and electrolyte additives. Electrolyte solutions containing vinyl ethylene carbonate (VEC), triphenyl phosphate (TPP), tris(trifluoroethyl)phosphate (TFP) as well as some proprietary flame-retardant additives were evaluated. Test cells in the 18,650 configuration were built at Sandia National Laboratories using new stable electrode materials and electrolyte additives. A special test fixture was designed to allow determination of self-generated cell heating during a thermal ramp profile. The flammability of vented gas and expelled electrolyte was studied using a novel arrangement of a spark generator placed near the cell to ignite vent gas if a flammable gas mixture was present. Flammability of vent gas was somewhat reduced by the presence of certain additives. Accelerating rate calorimetry (ARC) was also used to characterize 18,650-size test cell heat and gas generation. Gas composition was analyzed by gas chromatography (GC) and was found to consist of CO 2, H 2, CO, methane, ethane, ethylene and small amounts of C1-C4 organic molecules.

  11. Thermal stabilities of various rubber vulcanization cured by sulfur, peroxide and gamma radiation

    International Nuclear Information System (INIS)

    Basfar, A.A.; Shamshad Ahmed; Abdel Aziz, M.M.

    1999-01-01

    Sulfur and peroxide-cured rubber vulcanizates of NR and EPDM were obtained by blending the elastomers with fillers, antioxidants and appropriate accelerators, followed by vulcanization at 150 - 160 degree C. Blends of the same elastomers with appropriate co-agents and additives were also cured by gamma radiation at 150 and 200 kGy. A comparison of the thermal stabilities of these vulcanizates prepared by different curing techniques has been made by thermogravimetric analysis (TGA), assessed on the basis of comparison of DTG peak maxima, temperature for loss of 50% mass and actual thermal curves. The comparison reveals that the sulfur-cured vulcanizates are less thermally stable than their peroxide-cured counterparts. This may be attributed to the presence of a stronger C-C bond in case of peroxide-cured vulcanizates compared to weaker C-S sub x-C bond in case of sulfur-cured vulcanizates. However, compared to peroxide-cured vulcanizates, radiation-cured formulations demonstrated much improved thermal stability. This may originate from the existence of more uniformly distributed crosslinks and the enhanced rate of crosslink formation in the radiation process as compared to peroxide curing. In all the formulations whether sulfur, peroxide or radiation-cured, the natural rubber vulcanizates were found to be thermally much inferior to the synthetic contender, EPDM. Influence of variation of the amount of co-agent and other additives on the thermal stabilities of formulations of radiation cured NR and EPDM vulcanizates was also investigated

  12. Accelerated Metastable Solid-liquid Interdiffusion Bonding with High Thermal Stability and Power Handling

    Science.gov (United States)

    Huang, Ting-Chia; Smet, Vanessa; Kawamoto, Satomi; Pulugurtha, Markondeya R.; Tummala, Rao R.

    2018-01-01

    Emerging high-performance systems are driving the need for advanced packaging solutions such as 3-D integrated circuits (ICs) and 2.5-D system integration with increasing performance and reliability requirements for off-chip interconnections. Solid-liquid interdiffusion (SLID) bonding resulting in all-intermetallic joints has been proposed to extend the applicability of solders, but faces fundamental and manufacturing challenges hindering its wide adoption. This paper introduces a Cu-Sn SLID interconnection technology, aiming at stabilization of the microstructure in the Cu6Sn5 metastable phase rather than the usual stable Cu3Sn phase. This enables formation of a void-free interface yielding higher mechanical strength than standard SLID bonding, as well as significantly reducing the transition time. The metastable SLID technology retains the benefits of standard SLID with superior I/O pitch scalability, thermal stability and current handling capability, while advancing assembly manufacturability. In the proposed concept, the interfacial reaction is controlled by introducing Ni(P) diffusion barrier layers, designed to effectively isolate the metastable Cu6Sn5 phase preventing any further transformation. Theoretical diffusion and kinetic models were applied to design the Ni-Cu-Sn interconnection stack to achieve the targeted joint composition. A daisy chain test vehicle was used to demonstrate this technology as a first proof of concept. Full transition to Cu6Sn5 was successfully achieved within a minute at 260°C as confirmed by scanning electron microscope (SEM) and x-ray energy dispersive spectroscopy (XEDS) analysis. The joint composition was stable through 10× reflow, with outstanding bond strength averaging 90 MPa. The metastable SLID interconnections also showed excellent electromigration performance, surviving 500 h of current stressing at 105 A/cm2 at 150°C.

  13. The Electronic Library of the Thermal Physical Databases

    International Nuclear Information System (INIS)

    Zhuravleva, Y.; Mingaleeva, G.; Mokrousov, K.; Yashnikov, D.

    2008-01-01

    Up-to-date quality assurance procedure requires the permanent verification of the best-estimate thermal-hydraulic system codes and the uncertainty analysis of results. Therefore, the researches need the growing up amount of the experimental data. Over the last years RDIPE has been carried out the verification of RELAP5/mod3.2 code and safety analysis for NPP with RBMK reactor. Moreover, these activities include both Russian (Puchok, Korsar, RATEG) and foreign codes (RELAP, MELCOR, ATHLET). Such activities require of the accumulation and the assessment of the large amount of experimental data. Electronic data base library was created in order to unify and keep the large amount of the primary experimental data. The special attention was given to completeness and sufficiency of information for modelling of the experiments. Generally this activity was carried out in the collaboration with the authors of experiment. First of all the experimental data for the additional verification of Russian and foreign codes relating to RBMK reactor safety analysis were included in the library. The following phenomena are specific and important: outflow from the main circulation circuit including critical flow of water, two phases mixture and vapour through the break, flow limiters, long channels with/ without local resistance and other circuit elements; thermal hydraulic process in reactor channels: pressure-drop, relative movement of phases, countercurrent flow, reflooding; heat transfer in fuel bundles including radiation heat transfer; heat transfer before and after critical heat flux transition in the rod bundle; variation of steam-water level in drum separator. These phenomena were studied at the test sites of KPI (Ukraine), Lithuanian Energy Institute, RDIPE (Russia), Russian Research Center 'Kurchatov Institute', EREC (Russia) and others. Transient modes data from operating power plants became the important part of the library. The authors of the electronic thermal physical

  14. Thermal shock behavior of platinum aluminide bond coat/electron beam-physical vapor deposited thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Zhenhua, E-mail: zhxuciac@163.com [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); Dai, Jianwei [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); Niu, Jing [Shenyang Liming Aero-engine (Group) Corporation Ltd., Institute of Metallurgical Technology, Technical Center, Shengyang 110043 (China); Li, Na; Huang, Guanghong; He, Limin [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China)

    2014-12-25

    Highlights: • TBCs of (Ni, Pt)Al bond coat with grit blasting process and YSZ ceramic coating. • Grain boundary ridges are the sites for spallation damage initiation in TBCs. • Ridges removed, cavities formation appeared and the damage initiation deteriorated. • Damage initiation and progression at interface lead to a buckling failure. - Abstract: Thermal barrier coating systems (TBCs) including of chemical vapor deposited (Ni, Pt)Al bond coat with grit blasting process and electron beam physical vapor deposited Y{sub 2}O{sub 3}-stabilized-ZrO{sub 2} (YSZ) ceramic coating were investigated. The phase structures, surface and cross-sectional morphologies, thermal shock behaviors and residual stresses of the coatings were studied in detail. Grain boundary ridges still remain on the surface of bond coat prior to the deposition of the ceramic coating, which are shown to be the major sites for spallation damage initiation in TBCs. When these ridges are mostly removed, they appear some of cavities formation and then the damage initiation mode is deteriorated. Damage initiation and progression occurs at the bond coat to thermally grown oxide (TGO) interface leading to a buckling failure behavior. A buckle failure once started may be arrested when it runs into a region of high bond coat to TGO interface toughness. Thus, complete failure requires further loss in toughness of the bond coat to TGO interface during cooling. The suppressed cavities formation, the removed ridges at the grain boundaries, the relative high TGO to bond coat interface toughness, the uniform growth behavior of TGO thickening and the lower of the residual stress are the primary factors for prolonging the lifetime of TBCs.

  15. Thermal strain measurements in graphite using electronic speckle pattern interferometry

    International Nuclear Information System (INIS)

    Tamulevicius, S.; Augulis, L.; Augulis, R.; Zabarskas, V.; Levinskas, R.; Poskas, P.

    2001-01-01

    Two 1500 MW(e) RBMK Units are operated at Ignalina NPP in Lithuania. Due to recent decision of the Parliament on the earlier closure of Unit 1, preparatory work for decommissioning have been initiated. Preferred decommissioning strategy is based on delayed dismantling after rather long safe enclosure period. Since graphite is one of the basic and probably the most voluminous components of the reactor internals, a sufficient information on status and behaviour of graphite moderator and reflector during long time safe enclosure period is of special significance. In this context, thermal strain in graphite is one of the parameters requiring particular interest. Electronic speckle pattern interferometry has been proposed and successfully tested to control this parameter using the real samples of graphite from Ignalina NPP Units. (author)

  16. Laser aided direct metal deposition of Inconel 625 superalloy: Microstructural evolution and thermal stability

    International Nuclear Information System (INIS)

    Dinda, G.P.; Dasgupta, A.K.; Mazumder, J.

    2009-01-01

    Direct metal deposition technology is an emerging laser aided manufacturing technology based on a new additive manufacturing principle, which combines laser cladding with rapid prototyping into a solid freeform fabrication process that can be used to manufacture near net shape components from their CAD files. In the present study, direct metal deposition technology was successfully used to fabricate a series of samples of the Ni-based superalloy Inconel 625. A high power CO 2 laser was used to create a molten pool on the Inconel 625 substrate into which an Inconel 625 powder stream was delivered to create a 3D object. The structure and properties of the deposits were investigated using optical and scanning electron microscopy, X-ray diffraction and microhardness test. The microstructure has been found to be columnar dendritic in nature, which grew epitaxially from the substrate. The thermal stability of the dendritic morphology was investigated in the temperature range 800-1200 deg. C. These studies demonstrate that Inconel 625 is an attractive material for laser deposition as all samples produced in this study are free from relevant defects such as cracks, bonding error and porosity.

  17. Polyacrylonitrile nanofibers with added zeolitic imidazolate frameworks (ZIF-7) to enhance mechanical and thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Min Wook [Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, 842 W. Taylor St., Chicago, Illinois 60607-7022 (United States); An, Seongpil; Song, Kyo Yong; Joshi, Bhavana N.; Jo, Hong Seok; Yoon, Sam S., E-mail: skyoon@korea.ac.kr, E-mail: ayarin@uic.edu [School of Mechanical Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Al-Deyab, Salem S. [Department of Chemistry, King Saud University, Riyadh 11451 (Saudi Arabia); Yarin, Alexander L., E-mail: skyoon@korea.ac.kr, E-mail: ayarin@uic.edu [Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, 842 W. Taylor St., Chicago, Illinois 60607-7022 (United States); School of Mechanical Engineering, Korea University, Seoul 136-713 (Korea, Republic of)

    2015-12-28

    Zeolitic imidazolate framework 7/polyacrylonitrile (ZIF-7/PAN) nanofiber mat of high porosity and surface area can be used as a flexible fibrous filtration membrane that is subjected to various modes of mechanical loading resulting in stresses and strains. Therefore, the stress-strain relation of ZIF-7/PAN nanofiber mats in the elastic and plastic regimes of deformation is of significant importance for numerous practical applications, including hydrogen storage, carbon dioxide capture, and molecular sensing. Here, we demonstrated the fabrication of ZIF-7/PAN nanofiber mats via electrospinning and report their mechanical properties measured in tensile tests covering the elastic and plastic domains. The effect of the mat fabrication temperature on the mechanical properties is elucidated. We showed the superior mechanical strength and thermal stability of the compound ZIF-7/PAN nanofiber mats in comparison with that of pure PAN nanofiber mats. Material characterization including scanning electron microscope, energy-dispersive X-ray spectroscopy, tensile tests, differential scanning calorimetry, and Fourier transform infrared spectroscopy revealed the enhanced chemical bonds of the ZIF-7/PAN complex.

  18. Laser aided direct metal deposition of Inconel 625 superalloy: Microstructural evolution and thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Dinda, G.P., E-mail: dindag@focushope.edu [Center for Advanced Technologies, Focus: HOPE, Detroit, MI 48238 (United States); Center for Laser Aided Intelligent Manufacturing, University of Michigan, Ann Arbor, MI 48109 (United States); Dasgupta, A.K. [Center for Advanced Technologies, Focus: HOPE, Detroit, MI 48238 (United States); Mazumder, J. [Center for Laser Aided Intelligent Manufacturing, University of Michigan, Ann Arbor, MI 48109 (United States)

    2009-05-25

    Direct metal deposition technology is an emerging laser aided manufacturing technology based on a new additive manufacturing principle, which combines laser cladding with rapid prototyping into a solid freeform fabrication process that can be used to manufacture near net shape components from their CAD files. In the present study, direct metal deposition technology was successfully used to fabricate a series of samples of the Ni-based superalloy Inconel 625. A high power CO{sub 2} laser was used to create a molten pool on the Inconel 625 substrate into which an Inconel 625 powder stream was delivered to create a 3D object. The structure and properties of the deposits were investigated using optical and scanning electron microscopy, X-ray diffraction and microhardness test. The microstructure has been found to be columnar dendritic in nature, which grew epitaxially from the substrate. The thermal stability of the dendritic morphology was investigated in the temperature range 800-1200 deg. C. These studies demonstrate that Inconel 625 is an attractive material for laser deposition as all samples produced in this study are free from relevant defects such as cracks, bonding error and porosity.

  19. Plasma fluorination of vertically aligned carbon nanotubes: functionalization and thermal stability.

    Science.gov (United States)

    Struzzi, Claudia; Scardamaglia, Mattia; Hemberg, Axel; Petaccia, Luca; Colomer, Jean-François; Snyders, Rony; Bittencourt, Carla

    2015-01-01

    Grafting of fluorine species on carbon nanostructures has attracted interest due to the effective modification of physical and chemical properties of the starting materials. Various techniques have been employed to achieve a controlled fluorination yield; however, the effect of contaminants is rarely discussed, although they are often present. In the present work, the fluorination of vertically aligned multiwalled carbon nanotubes was performed using plasma treatment in a magnetron sputtering chamber with fluorine diluted in an argon atmosphere with an Ar/F2 ratio of 95:5. The effect of heavily diluted fluorine in the precursor gas mixture is investigated by evaluating the modifications in the nanotube structure and the electronic properties upon plasma treatment. The existence of oxygen-based grafted species is associated with background oxygen species present in the plasma chamber in addition to fluorine. The thermal stability and desorption process of the fluorine species grafted on the carbon nanotubes during the fluorine plasma treatment were evaluated by combining different spectroscopic techniques.

  20. Plasma fluorination of vertically aligned carbon nanotubes: functionalization and thermal stability

    Directory of Open Access Journals (Sweden)

    Claudia Struzzi

    2015-12-01

    Full Text Available Grafting of fluorine species on carbon nanostructures has attracted interest due to the effective modification of physical and chemical properties of the starting materials. Various techniques have been employed to achieve a controlled fluorination yield; however, the effect of contaminants is rarely discussed, although they are often present. In the present work, the fluorination of vertically aligned multiwalled carbon nanotubes was performed using plasma treatment in a magnetron sputtering chamber with fluorine diluted in an argon atmosphere with an Ar/F2 ratio of 95:5. The effect of heavily diluted fluorine in the precursor gas mixture is investigated by evaluating the modifications in the nanotube structure and the electronic properties upon plasma treatment. The existence of oxygen-based grafted species is associated with background oxygen species present in the plasma chamber in addition to fluorine. The thermal stability and desorption process of the fluorine species grafted on the carbon nanotubes during the fluorine plasma treatment were evaluated by combining different spectroscopic techniques.

  1. EFFECT OF FINITE LARMOR RADIUS CORRECTIONS ON THE THERMAL INSTABILITY OF THERMALLY CONDUCTING VISCOUS PLASMA WITH HALL CURRENT AND ELECTRON INERTIA

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Shweta; Sharma, Prerana [Physics Department, Ujjain Engineering College, Ujjain, MP-456010 (India); Kaothekar, Sachin [Physics Department, Mahakal Institute of Technology, Ujjain, MP-456664 (India); Chhajlani, R. K., E-mail: sackaothekar@gmail.com [Retired, School of Studies in Physics, Vikram University Ujjain, MP-456010 (India)

    2016-10-01

    The thermal instability of an infinite homogeneous, thermally conducting, and rotating plasma, incorporating finite electrical resistivity, finite electron inertia, and an arbitrary radiative heat-loss function in the presence of finite Larmor radius corrections and Hall current, has been studied. Analysis has been made with the help of linearized magnetohydrodynamics (MHD) equations. A general dispersion relation is obtained using the normal mode analysis method, and the dispersion relation is discussed for longitudinal propagation and transverse propagation separately. The dispersion relation has been solved numerically to obtain the dependence of the growth rate on the various parameters involved. The conditions of modified thermal instability and stability are discussed in the different cases of interest.

  2. Experimental Study of Turbine Fuel Thermal Stability in an Aircraft Fuel System Simulator

    Science.gov (United States)

    Vranos, A.; Marteney, P. J.

    1980-01-01

    The thermal stability of aircraft gas turbines fuels was investigated. The objectives were: (1) to design and build an aircraft fuel system simulator; (2) to establish criteria for quantitative assessment of fuel thermal degradation; and (3) to measure the thermal degradation of Jet A and an alternative fuel. Accordingly, an aircraft fuel system simulator was built and the coking tendencies of Jet A and a model alternative fuel (No. 2 heating oil) were measured over a range of temperatures, pressures, flows, and fuel inlet conditions.

  3. Optical and Thermal Stability of Oligofluorene/Rubber Luminescent Blend.

    Science.gov (United States)

    Barbosa, Camila G; Faez, Roselena; Péres, Laura O

    2016-09-01

    This paper proposes to obtain homogeneous and stable blends of oligo(9,9-dioctylfluorene)-co-phenylene (OF), a conjugated oligomer with strong tendency of formation of excimers in the solid state, and nitrile rubber (NBR). This rubber protection reduces the formation of polymer excimers in the films. The fluorene oligomer was synthesized via Suzuki reaction and incorporated in the nitrile rubber. The films were formed by spin coating and casting techniques on the proportions of 1, 5, 10, 20 and 50 % (w/w) of OF in the nitrile rubber (NBR). The structural, optical and thermal properties of the films were evaluated with infrared, UV-Vis, fluorescence and thermogravimetry, respectively. The nitrile rubber proved to be essential for the preparation of homogeneous and stable films, since it was not possible to obtain films with only fluorene using the above-mentioned techniques. Furthermore, luminescent properties of OF are unchanged and the excimers formation in the solid state decrease suggesting the efficiency of nitrile rubber as the matrix for making films.

  4. Stability of global entanglement in thermal states of spin chains

    International Nuclear Information System (INIS)

    Brennen, Gavin K.; Bullock, Stephen S.

    2004-01-01

    We investigate the entanglement properties of a one-dimensional chain of qubits coupled via nearest-neighbor spin-spin interactions. The entanglement measure used is the n-concurrence, which is distinct from other measures on spin chains such as bipartite entanglement in that it can quantify 'global' entanglement across the spin chain. Specifically, it computes the overlap of a quantum state with its time-reversed state. As such, this measure is well suited to study ground states of spin-chain Hamiltonians that are intrinsically time-reversal-symmetric. We study the robustness of n-concurrence of ground states when the interaction is subject to a time-reversal antisymmetric magnetic field perturbation. The n-concurrence in the ground state of the isotropic XX model is computed and it is shown that there is a critical magnetic field strength at which the entanglement experiences a jump discontinuity from the maximum value to zero. The n-concurrence for thermal mixed states is derived and a threshold temperature is computed below which the system has nonzero entanglement

  5. Thermal Stability Threshold for Amyloid Formation in Light Chain Amyloidosis

    Directory of Open Access Journals (Sweden)

    Tanya L. Poshusta

    2013-11-01

    Full Text Available Light chain (AL amyloidosis is a devastating disease characterized by amyloid deposits formed by immunoglobulin light chains. Current available treatments involve conventional chemotherapy and autologous stem cell transplant. We have recently concluded a phase III trial comparing these two treatments. AL amyloidosis patients who achieve hematological complete response (CR do not necessarily achieve organ response regardless of the treatment they received. In order to investigate the possible correlation between amyloid formation kinetics and organ response, we selected AL amyloidosis patients from the trial with kidney involvement and CR after treatment. Six patients were selected and their monoclonal immunoglobulin light chains were characterized. The proteins showed differences in their stability and their kinetics of amyloid formation. A correlation was detected at pH 7.4, showing that less stable proteins are more likely to form amyloid fibrils. AL-T03 is too unstable to form amyloid fibrils at pH 7.4. This protein was found in the only patient in the study that had organ response, suggesting that partially folded species are required for amyloid formation to occur in AL amyloidosis.

  6. Thermal stability and haemolytic effects of depolymerized guar gum derivatives.

    Science.gov (United States)

    Hussain, Majid; Zahoor, Tahir; Akhtar, Saeed; Ismail, Amir; Hameed, Aneela

    2018-03-01

    The purpose of current study was to purify and partially depolymerize guar gum by β-mannanase, HCl, Ba(OH) 2 actions and subjected to inspect compositional, thermogravimetric analysis (TGA) and haemolytic activity. Chemical composition revealed mannose and galactose ratio remained un-altered even after process of purification and hydrolysis. TGA thermograms affirmed initial and final decomposition temperature in various zones. Major decomposition stages apparently revealed partially hydrolyzed guar gum (PHGG) exhibited better heat stable properties having more zones of degradation than crude one. Furthermore, all guar fractions (2.5-250 mg/mL) were subjected to haemolysis to evaluate toxic effects during process of hydrolysis. The crude and hydrolyzed guar galactomannans exhibited minor haemolytic activity (1.9 ± 0.03-7.24 ± 0.02%) when compared to 0.1% Triton-X 100 (100% haemolysis) showing no toxic effects to human RBC's. Conclusively, hydrolyzed guar-galactomannans are safe and can be used in food products with improved heat stability.

  7. The relationship between fatty acid compositions and thermal stability of extra virgin olive oils

    OpenAIRE

    Fayegh Moulodi; Peyman Qajarbeigi; Ashraf Haj Hosseini Babaei; Asghar Mohammadpoor Asl

    2014-01-01

    Background: Fatty acids are one of the most important compounds in edible oils. Further, the stability of oils depends on the composition of fatty acids. So, this study was conducted to investigate the effect of fatty acid composition on the oxidative stability of extra virgin olive oils during the heating process. Methods: In total, eight samples of extra virgin olive oil were studied. To evaluate their thermal stability, the oils were heated at 120 ° C for 4 h and sampling was carried o...

  8. Investigation on Synthesis, Stability, and Thermal Conductivity Properties of Water-Based SnO2/Reduced Graphene Oxide Nanofluids

    Science.gov (United States)

    Yu, Xiaofen; Wu, Qibai; Zhang, Haiyan; Zeng, Guoxun; Li, Wenwu; Qian, Yannan; Li, Yang; Yang, Guoqiang; Chen, Muyu

    2017-01-01

    With the rapid development of industry, heat removal and management is a major concern for any technology. Heat transfer plays a critically important role in many sectors of engineering; nowadays utilizing nanofluids is one of the relatively optimized techniques to enhance heat transfer. In the present work, a facile low-temperature solvothermal method was employed to fabricate the SnO2/reduced graphene oxide (rGO) nanocomposite. X-ray diffraction (XRD), thermogravimetric analysis (TGA), X-ray photoelectron spectroscope (XPS), Raman spectroscopy, and transmission electron microscopy (TEM) have been performed to characterize the SnO2/rGO nanocomposite. Numerous ultrasmall SnO2 nanoparticles with average diameters of 3–5 nm were anchored on the surface of rGO, which contain partial hydrophilic functional groups. Water-based SnO2/rGO nanofluids were prepared with various weight concentrations by using an ultrasonic probe without adding any surfactants. The zeta potential was measured to investigate the stability of the as-prepared nanofluid which exhibited great dispersion stability after quiescence for 60 days. A thermal properties analyzer was employed to measure thermal conductivity of water-based SnO2/rGO nanofluids, and the results showed that the enhancement of thermal conductivity could reach up to 31% at 60 °C under the mass fraction of 0.1 wt %, compared to deionized water. PMID:29280972

  9. Investigation on Synthesis, Stability, and Thermal Conductivity Properties of Water-Based SnO2/Reduced Graphene Oxide Nanofluids

    Directory of Open Access Journals (Sweden)

    Xiaofen Yu

    2017-12-01

    Full Text Available With the rapid development of industry, heat removal and management is a major concern for any technology. Heat transfer plays a critically important role in many sectors of engineering; nowadays utilizing nanofluids is one of the relatively optimized techniques to enhance heat transfer. In the present work, a facile low-temperature solvothermal method was employed to fabricate the SnO2/reduced graphene oxide (rGO nanocomposite. X-ray diffraction (XRD, thermogravimetric analysis (TGA, X-ray photoelectron spectroscope (XPS, Raman spectroscopy, and transmission electron microscopy (TEM have been performed to characterize the SnO2/rGO nanocomposite. Numerous ultrasmall SnO2 nanoparticles with average diameters of 3–5 nm were anchored on the surface of rGO, which contain partial hydrophilic functional groups. Water-based SnO2/rGO nanofluids were prepared with various weight concentrations by using an ultrasonic probe without adding any surfactants. The zeta potential was measured to investigate the stability of the as-prepared nanofluid which exhibited great dispersion stability after quiescence for 60 days. A thermal properties analyzer was employed to measure thermal conductivity of water-based SnO2/rGO nanofluids, and the results showed that the enhancement of thermal conductivity could reach up to 31% at 60 °C under the mass fraction of 0.1 wt %, compared to deionized water.

  10. Carbon coated CoS_2 thermal battery electrode material with enhanced discharge performances and air stability

    International Nuclear Information System (INIS)

    Xie, Song; Deng, Yafeng; Mei, Jun; Yang, Zhaotang; Lau, Woon-Ming; Liu, Hao

    2017-01-01

    Graphical abstract: A novel carbon coated CoS_2 composite is prepared and investigated as a cathode material for thermal batteries. - Highlights: • A novel C@CoS_2 composite is successfully prepared by hydrothermal method. • The growth of CoS_2 in the glucose solution results in a smaller grain size. • The coating of carbon favors electron transfer and buffers polysulfides formation. • The in situ coated carbon layer effectively prevents the oxidation of CoS_2. • The C@CoS_2 composite shows competitive thermal stability and discharge property. - Abstract: Cobalt disulfide (CoS_2) is a promising thermal battery electrode material for its superior thermal stability and discharge performance. However, the low natural resource and poor air stability restrict its application in thermal battery fabrication. In this work, carbon coated CoS_2 composite was prepared by a facile one-pot hydrothermal method with glucose as carbon source. During the growth of CoS_2, the glucose molecules were in situ adsorbed and carbonized on the surface of the as-synthesized CoS_2, and the resultant carbon coating provided improved electrical conductivity and discharge performances to the composite. The thermal battery cell, which was fabricated with such a composite cathode and with a Li-Si anode, can output a capacity of 235.8 mAh g"−"1 and an energy density of 416.9 Wh kg"−"1 at a cut-off voltage of 1.7 V. This carbon coated CoS_2 composite also presented enhanced air stability. After being stored in dry air for 3 months, the composite can still provide a capacity of 232.4 mAh g"−"1 to 1.7 V, whereas the capacity of bare CoS_2 stored with the same condition dropped from 202.4 mAh g"−"1 to 189.7 mAh g"−"1.

  11. Thermal stability and phase transformation in fully indium oxide (InO{sub 1.5}) stabilized zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Piva, R.H., E-mail: honorato.piva@ua.pt; Piva, D.H.; Morelli, M.R.

    2017-01-15

    Indium oxide (InO{sub 1.5}) stabilized zirconia (InSZ) is an attractive material as electrolyte, or electrode, in solid oxide fuel cells (SOFCs), and as corrosion resistant top coat in thermal barrier coatings. However, little is known about the phase stability of cubic InSZ at temperatures that simulate the conditions in an operating SOFC or turbine. This article provides an investigation of the phase stability and phase transformations in cubic InSZ after heat treatments at 800, 1000, and 1200 °C for periods up to 2000 h. The results revealed that cubic InSZ is not stable during annealing at 1000 and 1200 °C, owing to a fast destabilization of the initial cubic phase to tetragonal, and eventually to monoclinic (c → t → m). The c → t → m transition in InSZ is intimately associated with the indium volatilization. On the other hand, cubic InSZ remained stable for 2000 h at 800 °C, although the partial formation of the tetragonal phase was observed along with a 0.25% contraction in the unit cell volume of the cubic phase, caused by short-range ordering. These results demonstrate that technological applications of cubic InSZ are restricted to temperatures at which the volatilization of the InO{sub 1.5} stabilizer does not occur. - Highlights: •Phase stability of fully InO{sub 1.5} stabilized zirconia (cubic InSZ) was evaluated. •Cubic InSZ is instable at temperatures ≥ 1000 °C, owing to the cubic-to-tetragonal-to-monoclinic destabilization. •Cubic InSZ undergoes the cubic-to-tetragonal transformation at ~ 800 °C. •Owing to the low phase stability, applications of cubic InSZ in TBCs or SOFCs are restricted.

  12. Effectiveness of electronic stability control on single-vehicle accidents.

    Science.gov (United States)

    Lyckegaard, Allan; Hels, Tove; Bernhoft, Inger Marie

    2015-01-01

    This study aims at evaluating the effectiveness of electronic stability control (ESC) on single-vehicle injury accidents while controlling for a number of confounders influencing the accident risk. Using police-registered injury accidents from 2004 to 2011 in Denmark with cars manufactured in the period 1998 to 2011 and the principle of induced exposure, 2 measures of the effectiveness of ESC were calculated: The crude odds ratio and the adjusted odds ratio, the latter by means of logistic regression. The logistic regression controlled for a number of confounding factors, of which the following were significant. For the driver: Age, gender, driving experience, valid driving license, and seat belt use. For the vehicle: Year of registration, weight, and ESC. For the accident surroundings: Visibility, light, and location. Finally, for the road: Speed limit, surface, and section characteristics. The present study calculated the crude odds ratio for ESC-equipped cars of getting in a single-vehicle injury accident as 0.40 (95% confidence interval [CI], 0.34-0.47) and the adjusted odds ratio as 0.69 (95% CI, 0.54-0.88). No difference was found in the effectiveness of ESC across the injury severity categories (slight, severe, and fatal). In line with previous results, this study concludes that ESC reduces the risk for single-vehicle injury accidents by 31% when controlling for various confounding factors related to the driver, the car, and the accident surroundings. Furthermore, it is concluded that it is important to control for human factors (at a minimum age and gender) in analyses where evaluations of this type are performed.

  13. Thermal equilibrium properties of an intense relativistic electron beam

    International Nuclear Information System (INIS)

    Davidson, R.C.; Uhm, H.S.

    1979-01-01

    The thermal equilibrium properties of an intense relativistic electron beam with distribution function f 0 /sub b/=Z -1 /sub b/exp[-(H-β/sub b/cP/sub z/-ω/sub b/P/sub theta/) /T] are investigated. This choice of f 0 /sub b/ allows for a mean azimuthal rotation of the beam electrons (when ω/sub b/not =0), and corresponds to an important generalization of the distribution function first analyzed by Bennett. Beam equilibrium properties, including axial velocity profile V 0 /sub z/b(r), azimuthal velocity profile V 0 /sub thetab/(r), beam temperature profile T 0 /sub b/(r), beam density profile n 0 /sub b/(r), and equilibrium self-field profiles, are calculated for a broad range of system parameters. For appropriate choice of beam rotation velocity ω/sub b/, it is found that radially confined equilibrium solutions [with n 0 /sub b/(r→infinity) =0] exist even in the absence of a partially neutralizing ion background that weakens the repulsive space-charge force. The necessary and sufficient conditions for radially confined equilibria are ω - /sub b/ + /sub b/ for 0 2 /sub b/p /ω 2 /sub b/c) (1-f-β 2 /sub b/) 2 /sub b/p/ω 2 /sub b/c) (1-f-β 2 /sub b/) <0

  14. Testing of High Thermal Cycling Stability of Low Strength Concrete as a Thermal Energy Storage Material

    Directory of Open Access Journals (Sweden)

    Chao Wu

    2016-09-01

    Full Text Available Concrete has the potential to become a solution for thermal energy storage (TES integrated in concentrating solar power (CSP systems due to its good thermal and mechanical properties and low cost of material. In this study, a low strength concrete (C20 is tested at high temperatures up to 600 °C. Specimens are thermally cycled at temperatures in the range of 400–300 °C, 500–300 °C, and 600–300 °C, which TES can reach in operation. For comparison, specimens also cycled at temperature in the range of 400–25 °C (room temperature, 500–25 °C, and 600–25 °C. It is found from the test results that cracks are not observed on the surfaces of concrete specimens until the temperature is elevated up to 500 °C. There is mechanical deterioration of concrete after exposure to high temperature, especially to high thermal cycles. The residual compressive strength of concrete after 10 thermal cycles between 600 °C and 300 °C is about 58.3%, but the specimens remain stable without spalling, indicating possible use of low strength concrete as a TES material.

  15. Pickering emulsions stabilized by whey protein nanoparticles prepared by thermal cross-linking

    NARCIS (Netherlands)

    Wu, Jiande; Shi, Mengxuan; Li, Wei; Zhao, Luhai; Wang, Ze; Yan, Xinzhong; Norde, Willem; Li, Yuan

    2015-01-01

    A Pickering (o/w) emulsion was formed and stabilized by whey protein isolate nanoparticles (WPI NPs). Those WPI NPs were prepared by thermal cross-linking of denatured WPI proteins within w/o emulsion droplets at 80. °C for 15. min. During heating of w/o emulsions containing 10% (w/v) WPI

  16. New class of thermosetting plastics has improved strength, thermal and chemical stability

    Science.gov (United States)

    Burns, E. A.; Dubrow, B.; Lubowitz, H. R.

    1967-01-01

    New class of thermosetting plastics has high hydrocarbon content, high stiffness, thermal stability, humidity resistance, and workability in the precured state. It is designated cyclized polydiene urethane, and is applicable as matrices to prepare chemically stable ablative materials for rocket nose cones of nozzles.

  17. Computer program for storage and retrieval of thermal-stability data for explosives

    International Nuclear Information System (INIS)

    Ashcraft, R.W.

    1981-06-01

    A computer program for storage and retrieval of thermal stability data has been written in HP Basic for the HP-9845 system. The data library is stored on a 9885 flexible disk. A program listing and sample outputs are included as appendices

  18. Improving the thermal dimensional stability of flexible polymer composite backing materials for ultrasound transducers

    NARCIS (Netherlands)

    State, M.; Brands, P.J.; Vosse, van de F.N.

    2010-01-01

    Novel ultrasound backing materials based on polymer composites with improved dimensional stability and low coefficient of thermal expansion are being developed and analyzed. For this purpose a filled epoxy resin (Stycast1265), a commonly used backing material, was considered reference material and

  19. Structure-activity relationships between sterols and their thermal stability in oil matrix.

    Science.gov (United States)

    Hu, Yinzhou; Xu, Junli; Huang, Weisu; Zhao, Yajing; Li, Maiquan; Wang, Mengmeng; Zheng, Lufei; Lu, Baiyi

    2018-08-30

    Structure-activity relationships between 20 sterols and their thermal stabilities were studied in a model oil system. All sterol degradations were found to be consistent with a first-order kinetic model with determination of coefficient (R 2 ) higher than 0.9444. The number of double bonds in the sterol structure was negatively correlated with the thermal stability of sterol, whereas the length of the branch chain was positively correlated with the thermal stability of sterol. A quantitative structure-activity relationship (QSAR) model to predict thermal stability of sterol was developed by using partial least squares regression (PLSR) combined with genetic algorithm (GA). A regression model was built with R 2 of 0.806. Almost all sterol degradation constants can be predicted accurately with R 2 of cross-validation equals to 0.680. Four important variables were selected in optimal QSAR model and the selected variables were observed to be related with information indices, RDF descriptors, and 3D-MoRSE descriptors. Copyright © 2018 Elsevier Ltd. All rights reserved.

  20. Improved thermal stability of gas-phase Mg nanoparticles for hydrogen storage

    NARCIS (Netherlands)

    Krishnan, Gopi; Palasantzas, G.; Kooi, B. J.

    2010-01-01

    This work focuses on improving the thermal stability of Mg nanoparticles (NPs) for use in hydrogen storage. Three ways are investigated that can achieve this goal. (i) Addition of Cu prevents void formation during NP production and reduces the fast evaporation/voiding of Mg during annealing. (ii)

  1. Why collagens best survived in fossils? Clues from amino acid thermal stability

    DEFF Research Database (Denmark)

    Wang, Shuang-Yin; Cappellini, Enrico; Zhang, Hong-Yu

    2012-01-01

    Explaining why type I collagens are preferentially preserved in the geological time scale remains a challenge. Several pieces of evidence indicate that its rich content in the bone and its unique, stable structure played key roles in its preservation. By considering the distinct thermal stability...

  2. Enhanced thermal stability of the thylakoid membranes from spruce. A comparison with selected angiosperms

    Czech Academy of Sciences Publication Activity Database

    Karlický, Václav; Kurasová, Irena; Ptáčková, B.; Večeřová, Kristýna; Urban, Otmar; Špunda, Vladimír

    2016-01-01

    Roč. 130, 1-3 (2016), s. 357-371 ISSN 0166-8595 R&D Projects: GA MŠk(CZ) LO1415; GA ČR GA13-28093S Institutional support: RVO:67179843 Keywords : Norway spruce * Thermal stability * Circular dichroism * Photosystem II organization * Thylakoid membrane Subject RIV: ED - Physiology Impact factor: 3.864, year: 2016

  3. A review of typical thermal fatigue failure models for solder joints of electronic components

    Science.gov (United States)

    Li, Xiaoyan; Sun, Ruifeng; Wang, Yongdong

    2017-09-01

    For electronic components, cyclic plastic strain makes it easier to accumulate fatigue damage than elastic strain. When the solder joints undertake thermal expansion or cold contraction, different thermal strain of the electronic component and its corresponding substrate is caused by the different coefficient of thermal expansion of the electronic component and its corresponding substrate, leading to the phenomenon of stress concentration. So repeatedly, cracks began to sprout and gradually extend [1]. In this paper, the typical thermal fatigue failure models of solder joints of electronic components are classified and the methods of obtaining the parameters in the model are summarized based on domestic and foreign literature research.

  4. Extracellular ascorbate stabilization as a result of transplasma electron transfer in Saccharomyces cerevisiae.

    Science.gov (United States)

    Santos-Ocaña, C; Navas, P; Crane, F L; Córdoba, F

    1995-12-01

    The presence of yeast cells in the incubation medium prevents the oxidation of ascrobate catalyzed by copper ions. Ethanol increases ascorbate retention. Pyrazole, an alcohol dehydrogenase inhibitor, prevents ascorbate stabilization by cells. Chelation of copper ions does not account for stabilization, since oxidation rates with broken or boiled cells or conditioned media are similar to control rates in the absence of cells. Protoplast integrity is needed to reach optimal values of stabilization. Chloroquine, a known inhibitor of plasma membrane redox systems, inhibits the ascorbate stabilization, the inhibition being partially reversed by coenzyme Q6. Chloroquine does not inhibit ferricyanide reduction. Growth of yeast in iron-deficient media to increase ferric ion reductase activity also increases the stabilization. In conclusion, extracellular ascorbate stabilization by yeast cells can reflect a coenzyme Q dependent transplasmalemma electron transfer which uses NADH as electron donor. Iron deficiency increases the ascorbate stabilization but the transmembrane ferricyanide reduction system can act independently of ascorbate stabilization.

  5. Effects of Mg doping on the gate bias and thermal stability of solution-processed InGaZnO thin-film transistors

    International Nuclear Information System (INIS)

    Su, Bo-Yuan; Chu, Sheng-Yuan; Juang, Yung-Der; Liu, Ssu-Yin

    2013-01-01

    Graphical abstract: Mg-doped IGZO TFTs showed improved TFT performance and thermal stability due to fewer oxygen deficiencies and less interface electron trapping. Highlights: •We fabricated Mg-doped IGZO TFTs with improved performance using solution-process. •Mg doping reduced the oxygen deficiencies and less interface electron trapping of a-IGZO films. •Mg dope-TFT showed high mobility of 2.35 cm 2 /V s and an on–off current ratio over 10 6 . •For better device stability (gate-bias and thermal stability) was proved. -- Abstract: The effects of magnesium (Mg) doping (molar ratio Mg/Zn = (0–10 at.%)) on solution-processed amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) grown using the sol–gel method are investigated. TFT devices fabricated with Mg-doped films showed an improved field-effect mobility of 2.35 cm 2 /V s and a subthreshold slope (S) of 0.42 V/dec compared to those of an undoped a-IGZO TFT (0.73 cm 2 /V s and 0.74 V/dec, respectively), and an on–off current ratio of over 10 6 . Moreover, the 5 at.% Mg-doped TFT device showed improved gate bias and thermal stability due to fewer oxygen deficiencies, smaller carrier concentration, and less interface electron trapping in the a-IGZO films

  6. Synthesis of Zirconium-Containing Polyhedral Oligometallasilsesquioxane as an Efficient Thermal Stabilizer for Silicone Rubber

    Directory of Open Access Journals (Sweden)

    Jiedong Qiu

    2018-05-01

    Full Text Available Free radicals play a negative role during the thermal degradation of silicone rubber (SR. Quenching free radicals is proposed to be an efficient way to improve the thermal-oxidative stability of SR. In this work, a novel zirconium-containing polyhedral oligometallasilsesquioxane (Zr-POSS with free-radical quenching capability was synthesized and characterized. The incorporation of Zr-POSS effectively improved the thermal-oxidative stability of SR. The T5 (temperature at 5% weight loss of SR/Zr-POSS significantly increased by 31.7 °C when compared to the unmodified SR. Notably, after aging 12 h at 280 °C, SR/Zr-POSS was still retaining about 65%, 60%, 75%, and 100% of the tensile strength, tear strength, elongation at break, and hardness before aging, respectively, while the mechanical properties of the unmodified SR were significantly decreased. The possible mechanism of Zr-POSS for improving the thermal-oxidative stability of SR was intensively studied and it was revealed that the POSS structure could act as a limiting point to suppress the random scission reaction of backbone. Furthermore, Zr could quench the free radicals by its empty orbital and transformation of valence states. Therefore, it effectively suppressed the thermal-oxidative degradation and crosslinking reaction of the side chains.

  7. Study on thermal stability and chemical structure of polyamide blended with small amount of Cu

    International Nuclear Information System (INIS)

    Arai, Tsuyoshi; Ueno, Tomonaga; Kajiya, Takafumi; Ishikawa, Tomoyuki; Takeda, Kunihiko

    2007-01-01

    The thermal stability and the chemical structure of Polyamide 66 (PA66) blended with a small amount of copper have been studied. The thermal degradation of the blend with 35 ppm or more of copper was restrained and no strong influence of the concentration of copper was observed. The molecular weight of PA66 decreased by the thermal aging process but the amount of decrease of the blend was smaller than that of the non-blend. The water uptake of the blend increased. The chemical structure, which was observed by IR and NMR, changed slightly by blending with copper after aging at higher temperatures. Multiple items influenced the thermal stability of PA66 blended with a small amount of copper instead of just one. Namely, the main chain of PA66 is cut by heat and the degree of the cut is restrained by the copper. The diffusion time of copper atoms that disperse uniformly in the PA66 matrix is short enough to cover the individual amide groups and the effect enlarges the entire configuration of the PA66 chain to enhance the thermal stability. (author)

  8. Network structure and thermal stability study of high temperature seal glass

    Science.gov (United States)

    Lu, K.; Mahapatra, M. K.

    2008-10-01

    High temperature seal glass has stringent requirement on glass thermal stability, which is dictated by glass network structures. In this study, a SrO-La2O3-Al2O3-B2O3-SiO2 based glass system was studied using nuclear magnetic resonance, Raman spectroscopy, and x-ray diffraction for solid oxide cell application purpose. Glass structural unit neighboring environment and local ordering were evaluated. Glass network connectivity as well as silicon and boron glass former coordination were calculated for different B2O3:SiO2 ratios. Thermal stability of the borosilicate glasses was studied after thermal treatment at 850 °C. The study shows that high B2O3 content induces BO4 and SiO4 structural unit ordering, increases glass localized inhomogeneity, decreases glass network connectivity, and causes devitrification. Glass modifiers interact with either silicon- or boron-containing structural units and form different devitrified phases at different B2O3:SiO2 ratios. B2O3-free glass shows the best thermal stability among the studied compositions, remaining stable after thermal treatment for 200 h at 850 °C.

  9. Structural properties, deformation behavior and thermal stability of martensitic Ti-Nb alloys

    Energy Technology Data Exchange (ETDEWEB)

    Boenisch, Matthias

    2016-06-10

    . Also, experimental evidence indicates a deformation-induced martensite to austenite (α'' → β) conversion. The influence of Nb content on the thermal stability and on the occurrence of decomposition reactions in martensitic Ti-Nb alloys is examined by isochronal differential scanning calorimetry, dilatometry and in-situ synchrotron X-ray diffraction complemented by transmission electron microscopy. The thermal decomposition and transformation behavior exhibits various phase transformation sequences during heating into the β-phase field in dependence of composition. Eventually, the transformation temperatures, interval, hysteresis and heat of the β <-> α'' martensitic transformation are investigated in relation to the Nb content. The results obtained in this study are useful for the development and optimization of β-stabilized Ti-based alloys for structural, Ni-free shape memory and/or superelastic, as well as for biomedical applications.

  10. Microstructure and thermal stability of Fe, Ti and Ag implanted Yttria-stabilized zirconia

    NARCIS (Netherlands)

    van Hassel, B.A.; van Hassel, B.A.; Burggraaf, Anthonie; Burggraaf, A.J.

    1991-01-01

    Yttria-stabilized zirconia (YSZ) was implanted with 15 keV Fe or Ti ions up to a dose of 8×1016 at cm−2. The resulting “dopant” concentrations exceeded the concentrations corresponding to the equilibrium solid solubility of Fe2O3 or TiO2 in YSZ. During oxidation in air at 400° C, the Fe and Ti

  11. Chemical and thermal stability of core-shelled magnetite nanoparticles and solid silica

    Science.gov (United States)

    Cendrowski, Krzysztof; Sikora, Pawel; Zielinska, Beata; Horszczaruk, Elzbieta; Mijowska, Ewa

    2017-06-01

    Pristine nanoparticles of magnetite were coated by solid silica shell forming core/shell structure. 20 nm thick silica coating significantly enhanced the chemical and thermal stability of the iron oxide. Chemical and thermal stability of this structure has been compared to the magnetite coated by mesoporous shell and pristine magnetite nanoparticles. It is assumed that six-membered silica rings in a solid silica shell limit the rate of oxygen diffusion during thermal treatment in air and prevent the access of HCl molecules to the core during chemical etching. Therefore, the core/shell structure with a solid shell requires a longer time to induce the oxidation of iron oxide to a higher oxidation state and, basically, even strong concentrated acid such as HCl is not able to dissolve it totally in one month. This leads to the desired performance of the material in potential applications such as catalysis and environmental protection.

  12. Effect of supramolecular organization of a cartilaginous tissue on thermal stability of collagen II

    Science.gov (United States)

    Ignat'eva, N. Yu.; Averkiev, S. V.; Lunin, V. V.; Grokhovskaya, T. E.; Obrezkova, M. V.

    2006-08-01

    The thermal stability of collagen II in various cartilaginous tissues was studied. It was found that heating a tissue of nucleus pulposus results in collagen II melting within a temperature range of 60-70°C; an intact tissue of hyaline cartilage (of nasal septum and cartilage endplates) is a thermally stable system, where collagen II is not denatured completely up to 100°C. It was found that partial destruction of glycosaminoglycans in hyaline cartilage leads to an increase in the degree of denaturation of collagen II upon heating, although a significant fraction remains unchanged. It was shown that electrostatic interactions of proteoglycans and collagen only slightly affect the thermal stability of collagen II in the tissues. Evidently, proteoglycan aggregates play a key role: they create topological hindrances for moving polypeptide chains, thereby reducing the configurational entropy of collagen macromolecules in the state of a random coil.

  13. Degradation mechanism and thermal stability of urea nitrate below the melting point

    International Nuclear Information System (INIS)

    Desilets, Sylvain; Brousseau, Patrick; Chamberland, Daniel; Singh, Shanti; Feng, Hongtu; Turcotte, Richard; Anderson, John

    2011-01-01

    Highlights: → Decomposition mechanism of urea nitrate. → Spectral characterization of the decomposition mechanism. → Thermal stability of urea nitrate at 50, 70 and 100 o C. → Chemical balance of decomposed products released. - Abstract: Aging and degradation of urea nitrate below the melting point, at 100 o C, was studied by using thermal analysis and spectroscopic methods including IR, Raman, 1 H and 13 C NMR techniques. It was found that urea nitrate was completely degraded after 72 h at 100 o C into a mixture of solids (69%) and released gaseous species (31%). The degradation mechanism below the melting point was clearly identified. The remaining solid mixture was composed of ammonium nitrate, urea and biuret while unreacted residual nitric and isocyanic acids as well as traces of ammonia were released as gaseous species at 100 o C. The thermal stability of urea nitrate, under extreme storage conditions (50 o C), was also examined by isothermal nano-calorimetry.

  14. Thermal stability of morpholine, AMP and sarcosine in PWR secondary systems. Laboratory and loop experiments

    International Nuclear Information System (INIS)

    Feron, D.; Lambert, I.

    1991-01-01

    Laboratory and loop tests have been carried out in order to investigate the thermal stability of three amines (morpholine, AMP and sarcosine) in PWR secondary conditions. Laboratory experiments have been performed in a titanium autoclave at 300 deg C. The results pointed out high thermal decomposition rates of AMP and sarcosine. A decomposition mechanism is proposed for the 3 amines. Loop tests have been performed in order to compare steam cycle conditioning with ammonia, morpholine and AMP. The amine concentrations and the decomposition products such as acetate and formate have been followed around the secondary circuit of the ORION loop which reproduces the main physico-chemical characteristics of a PWR secondary circuit. These concentrations are reported together with the evolution of cationic conductivities. The influence of oxygen concentration on amine thermal stability has been observed. Results are expressed also in terms of decomposition rates and of relative volatility

  15. High-temperature stability of chemically vapor-deposited tungsten-silicon couples rapid thermal annealed in ammonia and argon

    International Nuclear Information System (INIS)

    Broadbent, E.K.; Morgan, A.E.; Flanner, J.M.; Coulman, B.; Sadana, D.K.; Burrow, B.J.; Ellwanger, R.C.

    1988-01-01

    A rapid thermal anneal (RTA) in an NH 3 ambient has been found to increase the thermal stability of W films chemically vapor deposited (CVD) on Si. W films deposited onto single-crystal Si by low-pressure CVD were rapid thermal annealed at temperatures between 500 and 1100 0 C in NH 3 and Ar ambients. The reactions were studied using Rutherford backscattering spectrometry, x-ray diffraction, Auger electron spectroscopy, transmission electron microscopy, and four-point resistivity probe. High-temperature (≥1000 0 C) RTA in Ar completely converted W into the low resistivity (31 μΩ cm) tetragonal WSi 2 phase. In contrast, after a prior 900 0 C RTA in NH 3 , N inclusion within the W film and at the W/Si interface almost completely suppressed the W-Si reaction. Detailed examination, however, revealed some patches of WSi 2 formed at the interface accompanied by long tunnels extending into the substrate, and some crystalline precipitates in the substrate close to the interface. The associated interfacial contact resistance was only slightly altered by the 900 0 C NH 3 anneal. The NH 3 -treated W film acted as a diffusion barrier in an Al/W/Si contact metallurgy up to at least 550 0 C, at which point some increase in contact resistance was measured

  16. High-temperature stability of chemically vapor-deposited tungsten-silicon couples rapid thermal annealed in ammonia and argon

    Energy Technology Data Exchange (ETDEWEB)

    Broadbent, E.K.; Morgan, A.E.; Flanner, J.M.; Coulman, B.; Sadana, D.K.; Burrow, B.J.; Ellwanger, R.C.

    1988-12-15

    A rapid thermal anneal (RTA) in an NH/sub 3/ ambient has been found to increase the thermal stability of W films chemically vapor deposited (CVD) on Si. W films deposited onto single-crystal Si by low-pressure CVD were rapid thermal annealed at temperatures between 500 and 1100 /sup 0/C in NH/sub 3/ and Ar ambients. The reactions were studied using Rutherford backscattering spectrometry, x-ray diffraction, Auger electron spectroscopy, transmission electron microscopy, and four-point resistivity probe. High-temperature (greater than or equal to1000 /sup 0/C) RTA in Ar completely converted W into the low resistivity (31 ..mu cap omega.. cm) tetragonal WSi/sub 2/ phase. In contrast, after a prior 900 /sup 0/C RTA in NH/sub 3/, N inclusion within the W film and at the W/Si interface almost completely suppressed the W-Si reaction. Detailed examination, however, revealed some patches of WSi/sub 2/ formed at the interface accompanied by long tunnels extending into the substrate, and some crystalline precipitates in the substrate close to the interface. The associated interfacial contact resistance was only slightly altered by the 900 /sup 0/C NH/sub 3/ anneal. The NH/sub 3/-treated W film acted as a diffusion barrier in an Al/W/Si contact metallurgy up to at least 550 /sup 0/C, at which point some increase in contact resistance was measured.

  17. Preparation, characterization, and thermal stability of β-cyclodextrin/soybean lecithin inclusion complex.

    Science.gov (United States)

    Wang, Xinge; Luo, Zhigang; Xiao, Zhigang

    2014-01-30

    β-Cyclodextrin (β-CD), which is widely used to increase the stability, solubility, and bioavailability of guests, can form host-guest inclusion complexes with a wide variety of organic molecules. In this study the β-CD/soybean lecithin inclusion complex was prepared. The effect of reaction parameters such as reaction temperature, reaction time and the molar ratio of β-CD/soybean lecithin on inclusion ratio were studied. The inclusion ratio of the product prepared under the optimal conditions of β-CD/soybean lecithin molar ratio 2:1, reaction temperature 60°C reaction time 2h was 40.2%. The results of UV-vis, DSC, XRD and FT-IR spectrum indicated the formation of inclusion complex. The thermal stability experiment indicated that the thermal stability of soybean lecithin in inclusion complex was significantly improved compared with free soybean lecithin. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Improving thermal stability and efficacy of BCNU in treating glioma cells using PAA-functionalized graphene oxide

    Directory of Open Access Journals (Sweden)

    Lu YJ

    2012-03-01

    Full Text Available Yu-Jen Lu1,2,#, Hung-Wei Yang1,#, Sheng-Che Hung3, Chiung-Yin Huang2, Shin-Ming Li4, Chen-Chi M Ma4, Pin-Yuan Chen2, Hong-Chieh Tsai2, Kuo-Chen Wei2, Jyh-Ping Chen1 1Department of Chemical and Materials Engineering, Chang Gung University, Kwei-San, Taoyuan, Taiwan; 2Department of Neurosurgery, Chang Gung Memorial Hospital, Kwei-San, Taoyuan, Taiwan; 3Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan; 4Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan#These authors contributed equally to this workBackground: 1,3-bis(2-chloroethyl-1-nitrosourea (BCNU, a commercial chemotherapeutic drug for treating malignant brain tumors, has poor thermal stability and a short half-life. Immobilization of BCNU on a nanocarrier might increase the thermal stability of BCNU and extend its half-life.Methods: Nanosized graphene oxide (GO could be modified by polyacrylic acid (PAA to improve the aqueous solubility and increase the cell penetration efficacy of the nanocarrier. PAA–GO intended as a drug carrier for BCNU was prepared and characterized in this study. The size and thickness of PAA–GO was investigated by transmission electron microscopy and atomic force microscopy, and the presence of PAA functional groups was confirmed by electron spectroscopy for chemical analysis and thermogravimetric analysis. BCNU was conjugated to PAA–GO by covalent binding for specific killing of cancer cells, which could also enhance the thermal stability of the drug.Results: Single layer PAA–GO (about 1.9 nm with a lateral width as small as 36 nm was successfully prepared. The optimum drug immobilization condition was by reacting 0.5 mg PAA–GO with 0.4 mg BCNU, and the drug-loading capacity and residual drug activity were 198 µg BCNU/mg PAA–GO and 70%, respectively. This nanocarrier significantly prolonged the half-life of bound BCNU from 19 to 43 hours compared with free drug and showed efficient intracellular

  19. Electron beam induced strong organic/inorganic grafting for thermally stable lithium-ion battery separators

    Science.gov (United States)

    Choi, Yunah; Kim, Jin Il; Moon, Jungjin; Jeong, Jongyeob; Park, Jong Hyeok

    2018-06-01

    A tailored interface between organic and inorganic materials is of great importance to maximize the synergistic effects from hybridization. Polyethylene separators over-coated with inorganic thin films are the state-of-the art technology for preparing various secondary batteries with high safety. Unfortunately, the organic/inorganic hybrid separators have the drawback of a non-ideal interface, thus causing poor thermal/dimensional stability. Here, we report a straightforward method to resolve the drawback of the non-ideal interface between vapor deposited SiO2 and polyethylene separators, to produce a highly stable lithium-ion battery separator through strong chemical linking generated by direct electron beam irradiation. The simple treatment with an electron beam with an optimized dose generates thermally stable polymer separators, which may enhance battery safety under high-temperature conditions. Additionally, the newly formed Si-O-C or Si-CH3 chemical bonding enhances electrolyte-separator compatibility and thus may provide a better environment for ionic transport between the cathode and anode, thereby leading to better charge/discharge behaviors.

  20. Improvement of the thermal and thermo-oxidative stability of high-density polyethylene by free radical trapping of rare earth compound

    Energy Technology Data Exchange (ETDEWEB)

    Ran, Shiya; Zhao, Li; Han, Ligang [Laboratory of Polymer Materials and Engineering, Ningbo Institute of Technology, ZhejiangUniversity, Ningbo, 315100 (China); MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Institute of Polymer Composites, Zhejiang University, Hangzhou, 310027 (China); Guo, Zhenghong, E-mail: guozhenghong@nit.zju.edu.cn [Laboratory of Polymer Materials and Engineering, Ningbo Institute of Technology, ZhejiangUniversity, Ningbo, 315100 (China); Fang, Zhengping [Laboratory of Polymer Materials and Engineering, Ningbo Institute of Technology, ZhejiangUniversity, Ningbo, 315100 (China); MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Institute of Polymer Composites, Zhejiang University, Hangzhou, 310027 (China)

    2015-07-20

    Highlights: • Polyethylene filled with ytterbium trifluoromethanesulfonate was prepared. • A low Yb loading improved thermal stability of PE obviously by radical trapping. • Yb(OTf){sub 3} is expected to be an efficient thermal stabilizer for the polymer. - Abstract: A kind of rare earth compound, ytterbium trifluoromethanesulfonate (Yb(OTf){sub 3}), was introduced into high-density polyethylene (HDPE) by melt compounding to investigate the effect of Yb(OTf){sub 3} on the thermal and thermo-oxidative stability of HDPE. The results of thermogravimetric (TG) and differential scanning calorimetry (DSC) showed that the addition of Yb(OTf){sub 3} made the thermal degradation temperatures dramatically increased, the oxidative induction time (OIT) extended, and the enthalpy (ΔH{sub d}) reduced. Very low Yb(OTf){sub 3} loading (0.5 wt%) in HDPE could increase the onset degradation temperature in air from 334 to 407 °C, delay the OIT from 11.0 to 24.3 min, and decrease the ΔH{sub d} from 61.0 to 13.0 J/g remarkably. Electron spin resonance spectra (ESR), thermogravimetric analysis coupled to Fourier transform infrared spectroscopy (TGA-FTIR), rheological investigation and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) indicated that the free radicals-trapping ability of Yb(OTf){sub 3} was responsible for the improved thermal and thermo-oxidative stability.

  1. Thermal Management of Power Electronics and Electric Motors for Electric-Drive Vehicles (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Narumanchi, S.

    2014-09-01

    This presentation is an overview of the power electronics and electric motor thermal management and reliability activities at NREL. The focus is on activities funded by the Department of Energy Vehicle Technologies Office Advanced Power Electronics and Electric Motors Program.

  2. Recent advances in thermal analysis and stability evaluation of insensitive plastic bonded explosives (PBXs)

    International Nuclear Information System (INIS)

    Yan, Qi-Long; Zeman, Svatopluk; Elbeih, Ahmed

    2012-01-01

    Highlights: ► We summarize currently used insensitive polymer based explosives and their ingredients. ► We examine the calculation methods that are suitable for kinetic evaluation of polymer based explosives. ► The calculation method for thermal stability parameters of polymer based explosives are summarized, which mainly include shelf life, explosion delay, critical temperature, thermostability threshold, 500 day cookoff temperature and approximate time to explosion. ► The polymer bases could greatly affect the thermal properties of PBXs, including their thermal stability, kinetic parameters and thermodynamic properties. ► PBXs, containing some innovative energetic fillers such as CL-20, NTO, Fox-12 and BCHMX, are only at design stage, which need more research work in the future. - Abstract: In this paper, several fundamental investigations published over the past decades with regard to the thermal analysis of polymer-based explosives (PBXs) have been briefly reviewed. A number of explosive fillers and polymer bases that were used as their main ingredients of PBXs are summarized herein. In addition, the calculation methods for their decomposition kinetics and thermal stability parameters are also introduced in detail. It was concluded that only PBXs based on HMX, RDX and TATB have been widely investigated, and that some other PBXs containing innovative fillers, such as CL-20, TNAZ, NTO and BCHMX are at the design stage. The isoconversional methods and model fitting procedures are usually used to analyze the discrete thermolysis processes of PBXs. In addition, their thermal stability parameters such as shelf life, explosion delay, critical temperature, thermostability threshold, 500-day cookoff temperature and approximate time to explosion could be calculated easily from the kinetic data.

  3. THERMAL PROTECTION AND THERMAL STABILIZATION OF FIBER-OPTICAL GYROSCOPE INCLUDED IN STRAPDOWN INERTIAL NAVIGATION SYSTEM

    Directory of Open Access Journals (Sweden)

    D. S. Gromov

    2014-03-01

    Full Text Available It is known, that temperature perturbations and thermal modes have significant influence on the accuracy of a fiber-optical gyroscope. Nowadays, thermal perturbations are among the main problems in the field of navigation accuracy. Review of existing methods for decrease of temperature influences on the accuracy of a strapdown inertial navigation system with fiberoptical gyros showed, that the usage of constructive and compensation methods only is insufficient and, therefore, thermostabilization is required. Reversible thermostabilization system is offered, its main executive elements are thermoelectric modules (Peltier’s modules, heat transfer from which is provided by heatsinks at work surfaces of modules. This variant of thermostabilization maintenance is considered; Peltier’s modules and temperature sensors for the system are chosen. Parameters of heatsinks for heat transfer intensification are calculated. Fans for necessary air circulation in the device are chosen and thickness of thermal isolation is calculated. Calculations of thermal modes of navigation system with thermostabilization are made in modern software Autodesk Simulation CFD. Comparison of results for present and previous researches and calculations shows essential decrease in gradients of temperature on gyro surfaces and better uniformity of temperature field in the whole device. Conclusions about efficiency of the given method usage in view of accuracy improvement of navigation system are made. Thermostabilization provision of a strapdown inertial navigation system with fiberoptical gyros is proved. Thermostabilization application in combination with compensational methods can reach a necessary accuracy of navigation system.

  4. Extreme temperature stability of thermally insulating graphene-mesoporous-silicon nanocomposite

    Science.gov (United States)

    Kolhatkar, Gitanjali; Boucherif, Abderraouf; Rahim Boucherif, Abderrahim; Dupuy, Arthur; Fréchette, Luc G.; Arès, Richard; Ruediger, Andreas

    2018-04-01

    We demonstrate the thermal stability and thermal insulation of graphene-mesoporous-silicon nanocomposites (GPSNC). By comparing the morphology of GPSNC carbonized at 650 °C as-formed to that after annealing, we show that this nanocomposite remains stable at temperatures as high as 1050 °C due to the presence of a few monolayers of graphene coating on the pore walls. This does not only make this material compatible with most thermal processes but also suggests applications in harsh high temperature environments. The thermal conductivity of GPSNCs carbonized at temperatures in the 500 °C-800 °C range is determined through Raman spectroscopy measurements. They indicate that the thermal conductivity of the composite is lower than that of silicon, with a value of 13 ± 1 W mK-1 at room temperature, and not affected by the thin graphene layer, suggesting a role of the high concentration of carbon related-defects as indicated by the high intensity of the D-band compared to G-band of the Raman spectra. This morphological stability at high temperature combined with a high thermal insulation make GPSNC a promising candidate for a broad range of applications including microelectromechanical systems and thermal effect microsystems such as flow sensors or IR detectors. Finally, at 120 °C, the thermal conductivity remains equal to that at room temperature, attesting to the potential of using our nanocomposite in devices that operate at high temperatures such as microreactors for distributed chemical conversion, solid oxide fuel cells, thermoelectric devices or thermal micromotors.

  5. Thermal stability study of crystalline and novel spray-dried amorphous nilotinib hydrochloride.

    Science.gov (United States)

    Herbrink, Maikel; Vromans, Herman; Schellens, Jan; Beijnen, Jos; Nuijen, Bastiaan

    2018-01-30

    The thermal characteristics and the thermal degradation of crystalline and amorphous nilotinib hydrochloride (NH) were studied. The spray drying technique was successfully utilized for the amorphization of NH and was evaluated by spectroscopic techniques and differential scanning calorimetry (DSC). The ethanolic spray drying process yielded amorphous NH with a glass transition temperature (T g ) of 147°C. Thermal characterization of the amorphous phase was performed by heat capacity measurements using modulated DSC (mDSC). Thermal degradation was studied by thermogravimetric analysis (TGA). The derived thermodynamic properties of the amorphous NH indicate fragile behaviour and a low crystallization tendency. NH was found to be molecularly stable up to 193°C. After which, the thermal degradation displayed two phases. The values of the thermal degradation parameters were estimated using the Ozawa-Flynn-Wall and Friedman non-isothermal, model-free, isoconversional methods The results indicate the two phases to be single-step reactions. The examination of the physical stability of amorphous NH during storage and at elevated temperatures showed stability at 180°C for at least 5h and at 20-25°C/60% RH for at least 6 months. During these periods, no crystallization was observed. This study is the first to report the thermal characteristics of NH. Additionally, it is also the first to describe the full thermal analysis of a spray-dried amorphous drug. The thermal data may be used in the projection of future production processes and storage conditions of amorphous NH. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. A study on the structure and thermal stability of titanate nano-tubes as a function of sodium content

    Energy Technology Data Exchange (ETDEWEB)

    Morgado, E.; Abreu, M.A.S. de; Pravia, O.R.C. [Petrobras S.A./Cenpes, Research and Development Centre, Cidade Univ., Rio de Janeiro, RJ (Brazil); Marinkovic, B.A.; Jardim, P.M.; Rizzo, F.C. [Pontifical Catholic Univ., Dept. of Materials Science and Metallurgy, Rio de Janeiro (Brazil); Araujo, A.S. [University of Rio Grande do Norte, Dept. of Chemistry, RN (Brazil)

    2006-07-01

    Titanate Nano-Tubes (TTNT) were synthesized by hydrothermal treatment of TiO{sub 2} anatase in 10 M NaOH at 120 C followed by repeated water washing, with and without ion exchanging by HCl 0.1 M. Samples with different contents of remnant sodium in nano-tubes were characterized, as synthesized and after heat-treatment, by X-ray diffraction, transmission electron microscopy, thermal analysis and N{sub 2} adsorption. It was demonstrated that TTNT consisted of a tri-titanate structure with general formula Na{sub x}H{sub 2}-xTi{sub 3}O{sub 7}.nH{sub 2}O, where 0{<=}x{<=}2 and n{<=}1.2, depending on the degree of proton exchange after washing. As-synthesized nano-tubes retained interlayer water in its multi-walled structure. The removal of sodium reduced the amount of this intercalated water and increased the specific surface area, while thermal stability was reduced. The mechanism through which TTNT dehydrated and converted into their condensed titanates and/or TiO{sub 2} polymorphs after thermal treatment as a function of the sodium content was discussed and a schematic picture of the thermal transformations was proposed. (authors)

  7. A study on the structure and thermal stability of titanate nano-tubes as a function of sodium content

    International Nuclear Information System (INIS)

    Morgado, E.; Abreu, M.A.S. de; Pravia, O.R.C.; Marinkovic, B.A.; Jardim, P.M.; Rizzo, F.C.; Araujo, A.S.

    2006-01-01

    Titanate Nano-Tubes (TTNT) were synthesized by hydrothermal treatment of TiO 2 anatase in 10 M NaOH at 120 C followed by repeated water washing, with and without ion exchanging by HCl 0.1 M. Samples with different contents of remnant sodium in nano-tubes were characterized, as synthesized and after heat-treatment, by X-ray diffraction, transmission electron microscopy, thermal analysis and N 2 adsorption. It was demonstrated that TTNT consisted of a tri-titanate structure with general formula Na x H 2 -xTi 3 O 7 .nH 2 O, where 0≤x≤2 and n≤1.2, depending on the degree of proton exchange after washing. As-synthesized nano-tubes retained interlayer water in its multi-walled structure. The removal of sodium reduced the amount of this intercalated water and increased the specific surface area, while thermal stability was reduced. The mechanism through which TTNT dehydrated and converted into their condensed titanates and/or TiO 2 polymorphs after thermal treatment as a function of the sodium content was discussed and a schematic picture of the thermal transformations was proposed. (authors)

  8. The role of glycosylation and domain interactions in the thermal stability of human angiotensin-converting enzyme.

    Science.gov (United States)

    O'Neill, Hester G; Redelinghuys, Pierre; Schwager, Sylva L U; Sturrock, Edward D

    2008-09-01

    The N and C domains of somatic angiotensin-converting enzyme (sACE) differ in terms of their substrate specificity, inhibitor profiling, chloride dependency and thermal stability. The C domain is thermally less stable than sACE or the N domain. Since both domains are heavily glycosylated, the effect of glycosylation on their thermal stability was investigated by assessing their catalytic and physicochemical properties. Testis ACE (tACE) expressed in mammalian cells, mammalian cells in the presence of a glucosidase inhibitor and insect cells yielded proteins with altered catalytic and physicochemical properties, indicating that the more complex glycans confer greater thermal stabilization. Furthermore, a decrease in tACE and N-domain N-glycans using site-directed mutagenesis decreased their thermal stability, suggesting that certain N-glycans have an important effect on the protein's thermodynamic properties. Evaluation of the thermal stability of sACE domain swopover and domain duplication mutants, together with sACE expressed in insect cells, showed that the C domain contained in sACE is less dependent on glycosylation for thermal stabilization than a single C domain, indicating that stabilizing interactions between the two domains contribute to the thermal stability of sACE and are decreased in a C-domain-duplicating mutant.

  9. Comparison of Thermal Stability of Dry High-strength Concrete and Wet High-strength Concrete

    Science.gov (United States)

    Musorina, Tatiana; Katcay, Aleksandr; Selezneva, Anna; Kamskov, Victor

    2018-03-01

    High-strength concrete is a modern material, which occupies it`s own niche on the construction material market. It is applicable in a large-scale high-rise construction, particularly an underground construction is a frequently used solution for a space saving. Usually underground structure is related to a wet usage environment. Though not all properties of the high-strength concrete are investigated to the full extent. Under adverse climatic conditions of the Russian Federation one of the most important properties for constructional materials is a thermal capacity. Therefore, the main purpose of the paper is to compare a thermal capacity of the high-strength concrete in humid conditions and a thermal capacity of the high-strength concrete in dry operational condition. During the study dependency between thermal capacity and design wall thickness and ambient humidity has to be proven with two experiments. As a result the theoretical relation between thermal capacity characteristic - thermal inertia and wall thickness and ambient humidity was confirmed by the experimental data. The thermal capacity of a building is in direct ratio to the construction thickness. It follows from the experiments and calculations that wet high-strength concrete has less thermal stability.

  10. New method of thermal cycling stability test of phase change material

    Directory of Open Access Journals (Sweden)

    Putra Nandy

    2017-01-01

    Full Text Available Phase Change Material (PCM is the most promising material as thermal energy storage nowadays. As thermal energy storage, examination on endurance of material for long-term use is necessary to be carried out. Therefore, thermal cycling test is performed to ensure thermal stability of PCM. This study have found a new method on thermal cycling test of PCM sample by using thermoelectric as heating and cooling element. RT 22 HC was used as PCM sample on this thermal cycling test. The new method had many advantages compared to some references of the same test. It just needed a small container for PCM sample. The thermoelectric could release heat to PCM sample and absorb heat from PCM sample uniformly, respectively, was called as heating and cooling process. Hence, thermoelectric had to be supported by a relay control device to change its polarity so it could heat and cool PCM sample alternately and automatically. On the other hand, the thermoelectric was cheap, easy to be found and available in markets. It can be concluded that new method of thermal cycling test by using thermoelectric as source of heating and cooling can be a new reference for performing thermal cycling test on PCM.

  11. A Pathway to Reduce Energy Consumption in the Thermal Stabilization Process of Carbon Fiber Production

    Directory of Open Access Journals (Sweden)

    Srinivas Nunna

    2018-05-01

    Full Text Available Process parameters, especially in the thermal stabilization of polyacrylonitrile (PAN fibers, play a critical role in controlling the cost and properties of the resultant carbon fibers. This study aimed to efficiently handle the energy expense areas during carbon fiber manufacturing without reducing the quality of carbon fibers. We introduced a new parameter (recirculation fan frequency in the stabilization stage and studied its influence on the evolution of the structure and properties of fibers. Initially, the progress of the cyclization reaction in the fiber cross-sections with respect to fan frequencies (35, 45, and 60 Hz during stabilization was analyzed using the Australian Synchrotron-high resolution infrared imaging technique. A parabolic trend in the evolution of cyclic structures was observed in the fiber cross-sections during the initial stages of stabilization; however, it was transformed to a uniform trend at the end of stabilization for all fan frequencies. Simultaneously, the microstructure and property variations at each stage of manufacturing were assessed. We identified nominal structural variations with respect to fan frequencies in the intermediate stages of thermal stabilization, which were reduced during the carbonization process. No statistically significant variations were observed between the tensile properties of fibers. These observations suggested that, when using a lower fan frequency (35 Hz, it was possible to manufacture carbon fibers with a similar performance to those produced using a higher fan frequency (60 Hz. As a result, this study provided an opportunity to reduce the energy consumption during carbon fiber manufacturing.

  12. Examination of lignocellulosic fibers for chemical, thermal, and separations properties: Addressing thermo-chemical stability issues

    Science.gov (United States)

    Johnson, Carter David

    Natural fiber-plastic composites incorporate thermoplastic resins with fibrous plant-based materials, sometimes referred to as biomass. Pine wood mill waste has been the traditional source of natural fibrous feedstock. In anticipation of a waste wood shortage other fibrous biomass materials are being investigated as potential supplements or replacements. Perennial grasses, agricultural wastes, and woody biomass are among the potential source materials. As these feedstocks share the basic chemical building blocks; cellulose, hemicellulose, and lignin, they are collectively called lignocellulosics. Initial investigation of a number of lignocellulosic materials, applied to fiber-plastic composite processing and material testing, resulted in varied results, particularly response to processing conditions. Less thermally stable lignocellulosic filler materials were physically changed in observable ways: darkened color and odor. The effect of biomass materials' chemical composition on thermal stability was investigated an experiment involving determination of the chemical composition of seven lignocellulosics: corn hull, corn stover, fescue, pine, soy hull, soy stover, and switchgrass. These materials were also evaluated for thermal stability by thermogravimetric analysis. The results of these determinations indicated that both chemical composition and pretreatment of lignocellulosic materials can have an effect on their thermal stability. A second study was performed to investigate what effect different pretreatment systems have on hybrid poplar, pine, and switchgrass. These materials were treated with hot water, ethanol, and a 2:1 benzene/ethanol mixture for extraction times of: 1, 3, 6, 12, and 24 hours. This factorial experiment demonstrated that both extraction time and medium have an effect on the weight percent of extractives removed from all three material types. The extracted materials generated in the above study were then subjected to an evaluation of thermal

  13. Enhanced surface transfer doping of diamond by V{sub 2}O{sub 5} with improved thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, Kevin G., E-mail: k.crawford.2@research.gla.ac.uk; Moran, David A. J. [School of Engineering, University of Glasgow, Glasgow G12 8LT (United Kingdom); Cao, Liang [High Magnetic Field Laboratory, Chinese Academy of Sciences, 350 Shushanhu Road, Hefei 230031, Anhui (China); Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, Singapore 117542 (Singapore); Qi, Dongchen, E-mail: d.qi@latrobe.edu.au [Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria 3086 (Australia); Tallaire, Alexandre [LSPM-CNRS, Université Paris 13, Villetaneuse 93430 (France); Limiti, E.; Verona, C. [Department of Industrial Engineering, “Tor Vergata” University, Rome 00173 (Italy); Wee, Andrew T. S. [Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, Singapore 117542 (Singapore)

    2016-01-25

    Surface transfer doping of hydrogen-terminated diamond has been achieved utilising V{sub 2}O{sub 5} as a surface electron accepting material. Contact between the oxide and diamond surface promotes the transfer of electrons from the diamond into the V{sub 2}O{sub 5} as revealed by the synchrotron-based high resolution photoemission spectroscopy. Electrical characterization by Hall measurement performed before and after V{sub 2}O{sub 5} deposition shows an increase in hole carrier concentration in the diamond from 3.0 × 10{sup 12} to 1.8 × 10{sup 13 }cm{sup −2} at room temperature. High temperature Hall measurements performed up to 300 °C in atmosphere reveal greatly enhanced thermal stability of the hole channel produced using V{sub 2}O{sub 5} in comparison with an air-induced surface conduction channel. Transfer doping of hydrogen-terminated diamond using high electron affinity oxides such as V{sub 2}O{sub 5} is a promising approach for achieving thermally stable, high performance diamond based devices in comparison with air-induced surface transfer doping.

  14. Thermal stability of Trichoderma reesei c30 cellulase and aspergillus niger; -glucosidase after ph and chemical modification

    Energy Technology Data Exchange (ETDEWEB)

    Woodward, J.; Whaley, K.S.; Zachry, G.S.; Wohlpart, D.L.

    1981-01-01

    Treatment of Trichoderma reesei C30 cellulase at pH 10.0 for 1 h at room temperature increased its pH and thermal stability. Chemical modification of the free epsilon-amino groups of cellulase at pH 10.0 resulted in no further increase in stability. Such chemical modification, however, decreased the thermal stability of the cellulose-cellulase complex. On the contrary, the chemical modification of Aspergillus niger glucosidase with glutaraldehyde at pH 8.0 increased the thermal stability of this enzyme.

  15. Thermal stability of Trichoderma reesei C30 cellulase and Aspergillus niger. beta. -glucosidase after pH and chemical modification

    Energy Technology Data Exchange (ETDEWEB)

    Woodward, J.; Whaley, K.S.; Zachry, G.S.; Wohlpart, D.L.

    1981-01-01

    Treatment of Trichoderma reesei C30 cellulase at pH 10.0 for 1 h at room temperature increased its pH and thermal stability. Chemical modification of the free epsilon-amino groups of cellulase at pH 10.0 resulted in no further increase in stability. Such chemical modification, however, decreased the thermal stability of the cellulose-cellulase complex. On the contrary, the chemical modification of Aspergillus niger ..beta..-glucosidase with glutaraldehyde at pH 8.0 increased the thermal stability of this enzyme.

  16. Tribological and wear behavior of yttria stabilized zirconia thermal barrier coatings on mild steel

    International Nuclear Information System (INIS)

    Farooq, M.; Pervez, A.

    2012-01-01

    The perfection of the temperature confrontation of the engine essentials can be obtained by claim of a single ceramic thermal barrier coating (TBC) or several composite layers. Engine elements protected by TBC can work safely in elevated temperature range above 1000 degree C. Continuous endeavor to increase thermal resistance of engine the elements requires, apart from laboratory investigations, also numerical study of the different engine parts. The high temperatures and stress concentrations can act as the local sources of damage initiation and defects propagation in the form of cracks. The current study focuses the development of Yttria stabilized zirconia thermal barrier coating by Thermal spray technique. Mild steel was used as a substrate and the coating was then characterized for tribological analysis followed by the optical analysis of wear tracks and found the TBC behavior more promising then steel. (author)

  17. Data on blueberry peroxidase kinetic characterization and stability towards thermal and high pressure processing

    Directory of Open Access Journals (Sweden)

    Netsanet Shiferaw Terefe

    2017-08-01

    Full Text Available The data presented in this article are related to a research article entitled ‘Thermal and high pressure inactivation kinetics of blueberry peroxidase’ (Terefe et al., 2017 [1]. In this article, we report original data on the activity of partially purified blueberry peroxidase at different concentrations of hydrogen peroxide and phenlylenediamine as substrates and the effects of thermal and high pressure processing on the activity of the enzyme. Data on the stability of the enzyme during thermal (at temperatures ranging from 40 to 80 °C and combined thermal-high pressure processing (100–690 MPa, 30–90 °C are included in this report. The data are presented in this format in order to facilitate comparison with data from other researchers and allow statistical analyses and modeling by others in the field.

  18. Thermal Stability of Hexamethyldisiloxane (MM for High-Temperature Organic Rankine Cycle (ORC

    Directory of Open Access Journals (Sweden)

    Markus Preißinger

    2016-03-01

    Full Text Available The design of efficient Organic Rankine Cycle (ORC units for the usage of industrial waste heat at high temperatures requires direct contact evaporators without intermediate thermal oil circuits. Therefore, the thermal stability of high-temperature working fluids gains importance. In this study, the thermal degradation of hexamethyldisiloxane (MM is investigated in an electrically heated tube. Qualitative results concerning remarks on degradation products as well as quantitative results like the annual degradation rate are presented. It is shown that MM is stable up to a temperature of 300 °C with annual degradation rates of less than 3.5%. Furthermore, the break of a silicon–carbon bond can be a main chemical reaction that influences the thermal degradation. Finally, it is discussed how the results may impact the future design of ORC units.

  19. Synthesis and characterization of conducting composites of polyaniline and carbon black with high thermal stability

    Directory of Open Access Journals (Sweden)

    Fabio R. Simões

    2009-01-01

    Full Text Available In this work, a detailed chemical route to prepare thermally stable polyaniline (PANI/carbon black (CB composites is described. The syntheses were performed by chemical polymerization of aniline over CB particles, using different PANI/CB mass ratios. The thermal and electrical properties were characterized. Composites with mass ratio up to 65:35 (PANI:CB showed excellent thermal stability maintaining their conducting properties when thermally treated at 230 °C for two hours, which is adequate to process these materials. Moreover, the results showed an important reduction in the surface area of the composites which have a good relationship with the improvement of the rheological properties in melt processing.

  20. Theoretical study on thermal stability of molten salt for solar thermal power

    International Nuclear Information System (INIS)

    Wei, Xiaolan; Peng, Qiang; Ding, Jing; Yang, Xiaoxi; Yang, Jianping; Long, Bin

    2013-01-01

    Molten salt (HTS) composed of 53% KNO 3 , 40% NaNO 2 and 7 wt.% NaNO 3 has been used as heat transfer media and thermal storage fluid in the solar thermal power, but thermal decomposition will occur at higher temperature because of the oxidation of nitrite to nitrate in the air. In this paper, the reaction mechanism of NO 2 − oxidation is researched by quantum mechanical method. The results show that two components of the transition state (O 2 NO 2 − ) and intermediate ([NO 4 − ]) are found in the reaction. This reaction is an exothermic reaction and the activation barrier is 94.0 kJ mol −1 . The energy difference of this reaction is very large, so the reaction rate is very slow. -- Highlights: ► The mechanism of the oxidation of nitrite salt in HTS is explained. ► Two components of the transition state (O 2 NO 2 − ) and intermediate ([NO 4 − ]) are found. ► The activation barrier of the nitrite oxidation is determined