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Sample records for graphite design gatlinburg

  1. Graphite design handbook

    SciTech Connect

    Ho, F.H.

    1988-09-01

    The objectives of the Graphite Design Handbook (GDH) are to provide and maintain a single source of graphite properties and phenomenological model of mechanical behavior to be used for design of MHTGR graphite components of the Reactor System, namely, core support, permanent side reflector, hexagonal reflector elements, and prismatic fuel elements; to provide a single source of data and material models for use in MHTGR graphite component design, performance, and safety analyses; to present properties and equations representing material models in a form which can be directly used by the designer or analyst without the need for interpretation and is compatible with analytical methods and structural criteria used in the MHTGR project, and to control the properties and material models used in the MHTGR design and analysis to proper Quality Assurance standards and project requirements. The reference graphite in the reactor internal components is the nuclear grade 2020. There are two subgrades of interest, the cylinder nuclear grade and the large rectangular nuclear grade. The large rectangular nuclear grade is molded in large rectangular blocks. It is the reference material for the permanent side reflector and the central column support structure. The cylindrical nuclear grade is isostatically pressed and is intended for use as the core support component. This report gives the design properties for both H-451 and 2020 graphite as they apply to their respective criteria. The properties are presented in a form for design, performance, and safety calculations that define or validate the component design. 103 refs., 20 figs., 19 tabs.

  2. Gatlinburg conference: barometer of progress in analytical chemistry

    SciTech Connect

    Shults, W.D.

    1981-01-01

    Much progress has been made in the field of analytical chemistry over the past twenty-five years. The AEC-ERDA-DOE family of laboratories contributed greatly to this progress. It is not surprising then to find a close correlation between program content of past Gatlinburg conferences and developments in analytical methodology. These conferences have proved to be a barometer of technical status.

  3. Design development of graphite primary structures enables SSTO success

    SciTech Connect

    Biagiotti, V.A.; Yahiro, J.S.; Suh, D.E.; Hodges, E.R.; Prior, D.J.

    1997-01-01

    This paper describes the development of a graphite composite wing and a graphite composite intertank primary structure for application toward Single-Stage to Orbit space vehicles such as those under development in NASA{close_quote}s X-33/Reusable Launch Vehicle (RLV) Program. The trade study and designs are based on a Rockwell vertical take-off and horizontal landing (VTHL) wing-body RLV vehicle. Northrop Grumman{close_quote}s approach using a building block development technique is described. Composite Graphite/Bismaleimide (Gr/BMI) material characterization test results are presented. Unique intertank and wing composite subcomponent test article designs are described and test results to date are presented. Wing and intertank Full Scale Section Test Article (FSTA) objectives and designs are outlined. Trade studies, supporting building block testing, and FSTA demonstrations combine to develop graphite primary structure composite technology that enables developing X-33/RLV design programs to meet critical SSTO structural weight and operations performance criteria. {copyright} {ital 1997 American Institute of Physics.}

  4. AESOP XX: summary of proceedings. [Gatlinburg, Tennessee, April 24 to 26, 1979

    SciTech Connect

    1980-03-01

    The 20th meeting of the Association for Energy Systems, Operations, and Programming (AESOP) was held in Gatlinburg, Tennessee, on April 24 to 26, 1979. Representatives of DOE Headquarters discussed the effects that new security and privacy regulations will have on automatic data processing operations. The status and future possibilities of the Business Management Information System (BMIS) were also discussed. Then representatives of various DOE offices and contractors presented reports on various topics. This report contains two-page summaries of the papers presented at the meeting. Session topics and titles of papers were as follows: Washington report (New ADP issues; BMIS: the Business Management Information System; Nuclear weapons and the computer); Improving the productivity of the computing analyst/programer (What productivity improvement tools are available; Rocky Flats experience with SDM/70; Albuquerque Operations Office experience with SDM/70; Planning and project management; Minicomputer standards and programer productivity; MRC productivity gains through applications development tools); User viewpoints and expectations of data processing (User perspectives on computer applications; User viewpoints on environmental studies; Planning and implementing a procurement system; Two sides of the DP coin); Data base management (Use of data base systems within DOE; Future trends in data base hardware; Future trends in data base software; Toward automating the data base design process); and Management discussions. Complete versions of three of the papers have already been cited in ERA. These can be located by reference to the entry CONF-790431-- in the Report Number Index. (RWR)

  5. Design for a Unitary Graphite Composite Instrument Boom

    NASA Technical Reports Server (NTRS)

    Alexander, Wes; Carlos, Rene; Sturm, James; Rossoni, Peter

    2004-01-01

    This paper describes development of a Unitary graphite composite instrument boom that incorporates carpenter-tape like hinges for stowage. While light and stiff, graphite composite is not ordinarily thought of as a flexible material. This design has taken advantage of the stiffness of the composite in tubular geometry, yet leveraged its thin- section behavior to place flexibility at the required locations. Key is the proprietary layup, which results in a tough yet flexible hinge capable of rotating over 90 degrees in each direction. When the boom deploys, there is enough torque to overcome parasitic resistance from harness, etc. It will snap to the fully extended, rigid shape. The design has addressed materials issues such as out-of-plane bending, edge cracking, and interlaminar ply separation.

  6. H-451 graphite irradiation creep design model; Revision 1

    SciTech Connect

    1988-07-01

    Available irradiation creep data on H-451 graphite area analyzed and fitted to the proposed creep model in a standard linear solid (a linear viscoelastic model). A creep equation is obtained and recommended for preliminary design use. It is found that the regression is significant and the creep equation is a good predictor. The standard error (SE) of the estimate is smaller than that used in the core graphite criteria development. This smaller SE shall be used in all future work related to criteria development. The creep coefficient and/or model can be further improved if additional creep data can be obtained. For this purpose several creep experiments are recommended. The immediate one is to capsule 87M-2A currently under design.

  7. Designing a TAC thermometer from a VHTR graphite structure

    SciTech Connect

    Smith, James A. Kotter, Dale; Garrett, Steven L.; Ali, Randall A.

    2015-03-31

    The interior of a nuclear reactor presents a particularly harsh and challenging environment for both sensors and telemetry due to high temperatures and high fluxes of energetic and ionizing particles among the radioactive decay products. Very High Temperature Reactors are pushing the in core temperatures even higher. A unique sensing approach will be discussed to address the necessary high temperature measurements. Thermoacoustic thermometry exploits high temperatures and uses materials that are immune to the effects of ionizing radiation to create a temperature sensor that is self-powered and wireless. In addition, the form-factor for the Thermoacoustic Thermometer (TACT) can be designed to be integrated within common in-pile structures. There are no physical moving parts required for TACT and the sensor is self-powered, as it uses the nuclear fuel for its heat source. TACT data will be presented from a laboratory prototype mimicking the design necessary for a VHTR graphite structure.

  8. Designing a TAC thermometer from a VHTR graphite structure

    NASA Astrophysics Data System (ADS)

    Smith, James A.; Kotter, Dale; Garrett, Steven L.; Ali, Randall A.

    2015-03-01

    The interior of a nuclear reactor presents a particularly harsh and challenging environment for both sensors and telemetry due to high temperatures and high fluxes of energetic and ionizing particles among the radioactive decay products. Very High Temperature Reactors are pushing the in core temperatures even higher. A unique sensing approach will be discussed to address the necessary high temperature measurements. Thermoacoustic thermometry exploits high temperatures and uses materials that are immune to the effects of ionizing radiation to create a temperature sensor that is self-powered and wireless. In addition, the form-factor for the Thermoacoustic Thermometer (TACT) can be designed to be integrated within common in-pile structures. There are no physical moving parts required for TACT and the sensor is self-powered, as it uses the nuclear fuel for its heat source. TACT data will be presented from a laboratory prototype mimicking the design necessary for a VHTR graphite structure.

  9. Development of design data for graphite reinforced epoxy and polyimide composites

    NASA Technical Reports Server (NTRS)

    Scheck, W. G.

    1974-01-01

    Processing techniques and design data were characterized for a graphite/epoxy composite system that is useful from 75 K to 450 K, and a graphite/polyimide composite system that is useful from 75 K to 589 K. The Monsanto 710 polyimide resin was selected as the resin to be characterized and used with the graphite fiber reinforcement. Material was purchased using the prepreg specification for the design data generation for both the HT-S/710 and HM-S/710 graphite/polyimide composite system. Lamina and laminate properties were determined at 75 K, 297 K, and 589 K. The test results obtained on the skin-stringer components proved that graphite/polyimide composites can be reliably designed and analyzed much like graphite/epoxy composites. The design data generated in the program includes the standard static mechanical properties, biaxial strain data, creep, fatigue, aging, and thick laminate data.

  10. Design and development of high efficiency 140W space TWT with graphite collector

    NASA Astrophysics Data System (ADS)

    Srivastava, V.; Purohit, G.; Sharma, R. K.; Sharma, S. M.; Bera, A.; Bhaskar, P. V.; Singh, R. R.; Prasad, K.; Kiran, V.

    2008-05-01

    4-stage graphite collector assembly has been designed and developed for a 140W Ku-band space TWT to achieve the collector efficiency more than 80%. The UHV compatible, high density, copper impregnated POCO graphite (DFP-1C) was used to fabricate the four collector electrodes of the 4-stage depressed collector. Copper impregnated graphite material is used for the collector electrodes because of its low secondary electron emission coefficient, high thermal and electrical conductivities, easy machining and brazing, low thermal expansion coefficient and low weight. The graphite material was characterized for the UHV compatibility. The collector electrodes were precisely fabricated by careful machining, and technology was developed for brazing of graphite electrodes with high voltage alumina insulators. Complete TWT with four-stage graphite collector was developed and 140W output power at gain more than 55 dB was achieved. The TWT was pumped from both the gun and the collector ends.

  11. Design of Modern Reactors for Synthesis of Thermally Expanded Graphite

    NASA Astrophysics Data System (ADS)

    Strativnov, Eugene V.

    2015-05-01

    One of the most progressive trends in the development of modern science and technology is the creation of energy-efficient technologies for the synthesis of nanomaterials. Nanolayered graphite (thermally exfoliated graphite) is one of the key important nanomaterials of carbon origin. Due to its unique properties (chemical and thermal stability, ability to form without a binder, elasticity, etc.), it can be used as an effective absorber of organic substances and a material for seal manufacturing for such important industries as gas transportation and automobile. Thermally expanded graphite is a promising material for the hydrogen and nuclear energy industries. The development of thermally expanded graphite production is resisted by high specific energy consumption during its manufacturing and by some technological difficulties. Therefore, the creation of energy-efficient technology for its production is very promising.

  12. Design of Modern Reactors for Synthesis of Thermally Expanded Graphite.

    PubMed

    Strativnov, Eugene V

    2015-12-01

    One of the most progressive trends in the development of modern science and technology is the creation of energy-efficient technologies for the synthesis of nanomaterials. Nanolayered graphite (thermally exfoliated graphite) is one of the key important nanomaterials of carbon origin. Due to its unique properties (chemical and thermal stability, ability to form without a binder, elasticity, etc.), it can be used as an effective absorber of organic substances and a material for seal manufacturing for such important industries as gas transportation and automobile. Thermally expanded graphite is a promising material for the hydrogen and nuclear energy industries. The development of thermally expanded graphite production is resisted by high specific energy consumption during its manufacturing and by some technological difficulties. Therefore, the creation of energy-efficient technology for its production is very promising. PMID:26058505

  13. Improved High-Heat-Load Graphite Filter Design At CHESS Wiggler Beamlines

    SciTech Connect

    Savino, James J.; Shen Qun; Strieter, Gretchen; Fontes, Ernest; Pauling, Alan K.

    2004-05-12

    Conductively cooled highly-oriented pyrolytic graphite (HOPG) filters have been used at CHESS wiggler beamlines to protect downstream beryllium windows under high heat loads. In the past beam currents above 350 mA have caused excessively high temperatures on the existing HOPG filters, resulting in rapid sublimation of the graphite and drastic shortening of filter lifetimes. A new filter design which eliminates some drawbacks of the existing design is described. The new design utilizes a slotted water jet, which cools a thin, 'compliant' graphite-copper braze joint. Heat-transfer enhancements should enable an installed filter to survive beam currents of 450 mA. Optimization of design features and analysis results are discussed.

  14. Development of design allowable data for Celion 6000/LARC-160, graphite/polyimide composite laminates

    NASA Technical Reports Server (NTRS)

    Ehret, R. M.; Scanlan, P. R.; Rosen, C. D.

    1982-01-01

    A design allowables test program was conducted on Celion 6000/LARC-160 graphite polyimide composite to establish material performance over a 116 K (-250 F) to 589 K (600 F) temperature range. Tension, compression, in-plane shear and short beam shear properties were determined for uniaxial, quasi-isotropic and + or - 45 deg laminates. Effects of thermal aging and moisture saturation on mechanical properties were also evaluated. Celion 6000/LARC-160 graphite/polyimide can be considered an acceptable material system for structural applications to 589 K (600 F).

  15. Design, fabrication and test of graphite/epoxy metering truss structure components, phase 3

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The design, materials, tooling, manufacturing processes, quality control, test procedures, and results associated with the fabrication and test of graphite/epoxy metering truss structure components exhibiting a near zero coefficient of thermal expansion are described. Analytical methods were utilized, with the aid of a computer program, to define the most efficient laminate configurations in terms of thermal behavior and structural requirements. This was followed by an extensive material characterization and selection program, conducted for several graphite/graphite/hybrid laminate systems to obtain experimental data in support of the analytical predictions. Mechanical property tests as well as the coefficient of thermal expansion tests were run on each laminate under study, the results of which were used as the selection criteria for the single most promising laminate. Further coefficient of thermal expansion measurement was successfully performed on three subcomponent tubes utilizing the selected laminate.

  16. Saturated Fractional Design of Experiments: Toughness and Graphite Phase Optimizing in Nihard Cast Irons

    NASA Astrophysics Data System (ADS)

    Asensio-Lozano, J.; Álvarez-Antolín, J. F.

    2008-04-01

    The aim of the present research is to identify the manufacturing factors that exert an active influence on the graphite phase formation in mottled Nihard cast irons constituting the roll shells of duplex work rolls processed by the double pour method during centrifugal casting. The studied rolls, referred to as alloy indefinite chill, were processed at industrial scale and had a core consisting of spheroidal graphite cast iron with a matrix of ferrite and pearlite. An additional aim of this study was to evaluate the effect and extent of these factors on the dynamic toughness response of the roll shell material. The research methodology employed consisted of the application of a saturated design of experiments with seven factors, eight experiments, and resolution III. The measured responses for graphite were: the volume fraction, count number per unit area, and morphology, determined by quantitative metallography. Impact testing was characterized by Charpy tests on U-notched specimens at 350 °C. The manufacturing factors studied were: the final weight percent of silicon, sulfur, and manganese; the liquidus and the casting temperatures; and, finally, inoculation with SiCaMn and A-type FeSi (with Zr). The statistical experimental method conducted allowed us to confirm the significance of factors such as the %Si, the liquidus temperature and inoculation with SiCaMn on the precipitation of graphite in a white cast iron such as the Nihard irons used in the roll shell, in agreement with the precipitation of graphite in gray cast irons widely reported in the literature. It was also shown that the development of lamellar graphite shapes were favored by an increase in the total equivalent carbon and also by the increase in the amount of A-type FeSi added. Furthermore, the impact toughness was shown to improve with the increase in both the %Si and the liquidus temperature.

  17. Design and testing of thermal-expansion-molded graphite-epoxy hat-stiffened sandwich panels

    NASA Technical Reports Server (NTRS)

    Jegley, Dawn C.

    1989-01-01

    Minimum weight configurations for two types of graphite-epoxy hat-stiffened compression-loaded panels fabricated by the thermal-expansion-molding (TEM) manufacturing process were evaluated analytically and experimentally for designs with load index Nx/L values ranging from 100 to 800. The two types of panels contain graphite-epoxy face sheets with a foam core and hat stiffeners which are either open or filled with foam. Constraints on the extensional and shear stiffnesses are imposed on the design so that the panels will satisfy typical constraints for aircraft wing structures. Optimal structurally efficient TEM panels are compared to commercially available aluminum aircraft structures. Predicted load-strain relationships agree well with experimental results. Significant impact damage to the unstiffened face sheet and foam core does not noticeably reduce the load carrying ability of the panels, but damage to the stiffened face sheet reduces the failure load by 20 percent compared to unimpacted panels.

  18. Design, fabrication, and test of a graphite/epoxy metering truss. [as applied to the LST

    NASA Technical Reports Server (NTRS)

    Oken, S.; Skoumal, D. E.

    1975-01-01

    A graphite/epoxy metering truss as applied to the large space telescope was investigated. A full-scale truss was designed, fabricated and tested. Tests included static limit loadings, a modal survey and thermal-vacuum distortion evaluation. The most critical requirement was the demonstration of the dimensional stability provided by the graphite/epoxy truss concept. Crucial to the attainment of this objective was the ability to make very sophisticated thermal growth measurements which was provided by a seven beam laser interferometer. The design of the basic truss elements were tuned to provide the high degree of dimensional stability and stiffness required by the truss. The struts and spider assembly were fabricated with Fiberite's AS/934 and HMS/934 broadgoods. The rings utilized T300 graphite fabricate with the same materials. The predicted performance of the truss was developed using the NASTRAN program. These results showed conformance with the critical stiffness and thermal distortion requirements and correlated well with the test results.

  19. Brazing graphite to graphite

    DOEpatents

    Peterson, George R.

    1976-01-01

    Graphite is joined to graphite by employing both fine molybdenum powder as the brazing material and an annealing step that together produce a virtually metal-free joint exhibiting properties similar to those found in the parent graphite. Molybdenum powder is placed between the faying surfaces of two graphite parts and melted to form molybdenum carbide. The joint area is thereafter subjected to an annealing operation which diffuses the carbide away from the joint and into the graphite parts. Graphite dissolved by the dispersed molybdenum carbide precipitates into the joint area, replacing the molybdenum carbide to provide a joint of virtually graphite.

  20. Conceptual design of a high throughput electrorefining of a uranium by using graphite cathode

    SciTech Connect

    Lee, J.H.; Kang, Y.H.; Hwang, S.C.; Park, S.B.; Shim, J.B.; Lee, H.S.; Kim, E.H.; Park, S.W.

    2007-07-01

    Conceptual designing of a high throughput electro-refiner was performed by using basic experimental data and a commercial computational fluid dynamic code, CFX. An electro-refiner concept equipped with a graphite cathode bundle was designed to recover a high purity uranium product continuously without a noble metal contamination. The performance of the process for a decontamination of a noble metal in a uranium product was evaluated as a function of the process parameters such as the rotation speeds of the stirrer and the anode basket. (authors)

  1. Controlling the number of graphene sheets exfoliated from graphite by designed normal loading and frictional motion

    SciTech Connect

    Lee, Seungjun; Lu, Wei

    2014-07-14

    We use molecular dynamics to study the exfoliation of patterned nanometer-sized graphite under various normal loading conditions for friction-induced exfoliation. Using highly ordered pyrolytic graphite (HOPG) as well as both amorphous and crystalline SiO{sub 2} substrate as example systems, we show that the exfoliation process is attributed to the corrugation of the HOPG surface and the atomistic roughness of the substrate when they contact under normal loading. The critical normal strain, at which the exfoliation occurs, is higher on a crystalline substrate than on an amorphous substrate. This effect is related to the atomistic flatness and stiffness of the crystalline surface. We observe that an increase of the van der Waals interaction between the graphite and the substrate results in a decrease of the critical normal strain for exfoliation. We find that the magnitude of the normal strain can effectively control the number of exfoliated graphene layers. This mechanism suggests a promising approach of applying designed normal loading while sliding to pattern controlled number of graphene layers or other two-dimensional materials on a substrate surface.

  2. Design, fabrication and test of graphite/polyimide composite joints and attachments for advanced aerospace vehicles

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The development of several types of graphite/polyimide (GR/PI) bonded and bolted joints is reported. The program consists of two concurrent tasks: (1) design and test of specific built up attachments; and (2) evaluation of standard advanced bonded joint concepts. A data base for the design and analysis of advanced composite joints for use at elevated temperatures (561K (550 deg F)) to design concepts for specific joining applications, and the fundamental parameters controlling the static strength characteristics of such joints are evaluated. Data for design and build GR/PI of lightly loaded flight components for advanced space transportation systems and high speed aircraft are presented. Results for compression and interlaminar shear strengths of Celion 6000/PMR-15 laminates are given. Static discriminator test results for type 3 and type 4 bonded and bolted joints and final joint designs for TASK 1.4 scale up fabrication and testing are presented.

  3. Design and fabrication of graphite-epoxy bolted wing skin splice specimens

    NASA Technical Reports Server (NTRS)

    Johnson, R. W.; Mccarty, J. E.

    1977-01-01

    Graphite-epoxy bolted joint specimens were designed and fabricated. These specimens were to be representative of a side-of-body wing skin splice with a 20-year life expectancy in a commercial transport environment. Preliminary tests were performed to determine design values of bearing and net tension stresses. Based upon the information developed, a three-fastener-wide representative wing skin splice was designed for a load of 2627 KN/m (15,000 lbf/in.). One joint specimen was fabricated and tested at NASA. The wing skin splice failed at 106 percent of design ultimate load. This joint design achieved all static load objectives. Fabrication of six specimens, together with their loading fixtures, was completed, and the specimens were delivered to NASA-LRC.

  4. Analysis, design, and test of a graphite/polyimide Shuttle orbiter body flap segment

    NASA Technical Reports Server (NTRS)

    Graves, S. R.; Morita, W. H.

    1982-01-01

    For future missions, increases in Space Shuttle orbiter deliverable and recoverable payload weight capability may be needed. Such increases could be obtained by reducing the inert weight of the Shuttle. The application of advanced composites in orbiter structural components would make it possible to achieve such reductions. In 1975, NASA selected the orbiter body flap as a demonstration component for the Composite for Advanced Space Transportation Systems (CASTS) program. The progress made in 1977 through 1980 was integrated into a design of a graphite/polyimide (Gr/Pi) body flap technology demonstration segment (TDS). Aspects of composite body flap design and analysis are discussed, taking into account the direct-bond fibrous refractory composite insulation (FRCI) tile on Gr/Pi structure, Gr/Pi body flap weight savings, the body flap design concept, and composite body flap analysis. Details regarding the Gr/Pi technology demonstration segment are also examined.

  5. Design and implementation of automatic opto-electrical detection system for spheroidal graphite cast iron metallographic phase

    NASA Astrophysics Data System (ADS)

    Meng, Qing-xin; Xiao, Ze-xin; Deng, Shi-chao

    2010-11-01

    Spheroidal graphite cast iron,with excellent mechanical properties,is widely used in manufacturing many advanced castings,such as crankshaft,gears,pistons,and a variety of machine parts.Its microstructure morphology reflects the quality performance of the products,which leads to an urgent need for a simple,accurate and automatic microstructure morphology detection technique for detecting the quality of spheroidal graphite cast iron.In this paper,opto-electrical detection technique is employed for designing a spheroidal graphite cast iron microstructure automatic detection system,in which the microstructure is imaged by optical microscopy system,and the digital images are obtained by industrial cameras and sent to the computer.A series of digital image processing algorithms,including gray transformation, binarization,edge detection,image morphology and seed filling etc,are adopted to calculate and analyze the microstructure images.The morphology and microstructure analysis methods are combined to obtain the characteristic parameters such as the size of the graphite,the ball classification,the number of graphite nodules and so on.The experiment results show that this method is simple,fast,and accurate and can be employed for assessment of the spheroidal graphite cast iron metallographic phase instead of manual detection.

  6. Multidisciplinary Simulation of Graphite-Composite and Cermet Fuel Elements for NTP Point of Departure Designs

    NASA Technical Reports Server (NTRS)

    Stewart, Mark E.; Schnitzler, Bruce G.

    2015-01-01

    This paper compares the expected performance of two Nuclear Thermal Propulsion fuel types. High fidelity, fluid/thermal/structural + neutronic simulations help predict the performance of graphite-composite and cermet fuel types from point of departure engine designs from the Nuclear Thermal Propulsion project. Materials and nuclear reactivity issues are reviewed for each fuel type. Thermal/structural simulations predict thermal stresses in the fuel and thermal expansion mis-match stresses in the coatings. Fluid/thermal/structural/neutronic simulations provide predictions for full fuel elements. Although NTP engines will utilize many existing chemical engine components and technologies, nuclear fuel elements are a less developed engine component and introduce design uncertainty. Consequently, these fuel element simulations provide important insights into NTP engine performance.

  7. Design, fabrication and test of graphite/polyimide composite joints and attachments. [spacecraft control surfaces

    NASA Technical Reports Server (NTRS)

    Cushman, J. B.; Mccleskey, S. F.; Ward, S. H.

    1982-01-01

    The design, analysis, and testing performed to develop four types of graphite/polyimide (Gr/PI) bonded and bolted composite joints for lightly loaded control surfaces on advanced space transportation systems that operate at temperatures up to 561 K (550 F) are summarized. Material properties and small specimen tests were conducted to establish design data and to evaluate specific design details. Static discriminator tests were conducted on preliminary designs to verify structural adequacy. Scaled up specimens of the final joint designs, representative of production size requirements, were subjected to a series of static and fatigue tests to evaluate joint strength. Effects of environmental conditioning were determined by testing aged (125 hours at 589 K (600 F)) and thermal cycled (116 K to 589 K (-250 F to 600 F), 125 times) specimens. It is concluded Gr/PI joints can be designed and fabricated to carry the specified loads. Test results also indicate a possible resin loss or degradation of laminates after exposure to 589 K (600 F) for 125 hours.

  8. Stiffener attachment concepts for graphite-epoxy panels designed for postbuckling strength

    NASA Technical Reports Server (NTRS)

    Dickson, John N.; Biggers, Sherrill B.; Starnes, James H., Jr.

    1985-01-01

    Stiffener attachment concepts for suppressing or delaying the onset of the skin-stiffener separation failure mode in graphite-epoxy compression panels designed for postbuckling strength were experimentally studied. The effectiveness of these concepts was evaluated using panels with 16-ply skins and a single centrally-located I-shaped stiffener with both static and cyclic compressive loadings. Analytical results suggest that tailoring the relative thicknesses of the panel skin, stiffener attachment flange, and the stiffener web rotational stiffness can minimize the adverse effects of high interface shear and normal stresses. Interface stress levels may be reduced by tapering the thickness of the stiffener attachment flange and properly selecting the stacking sequences of the skin and stiffener attachment flange laminates.

  9. Molecular design driving tetraporphyrin self-assembly on graphite: a joint STM, electrochemical and computational study

    NASA Astrophysics Data System (ADS)

    El Garah, M.; Santana Bonilla, A.; Ciesielski, A.; Gualandi, A.; Mengozzi, L.; Fiorani, A.; Iurlo, M.; Marcaccio, M.; Gutierrez, R.; Rapino, S.; Calvaresi, M.; Zerbetto, F.; Cuniberti, G.; Cozzi, P. G.; Paolucci, F.; Samorì, P.

    2016-07-01

    Tuning the intermolecular interactions among suitably designed molecules forming highly ordered self-assembled monolayers is a viable approach to control their organization at the supramolecular level. Such a tuning is particularly important when applied to sophisticated molecules combining functional units which possess specific electronic properties, such as electron/energy transfer, in order to develop multifunctional systems. Here we have synthesized two tetraferrocene-porphyrin derivatives that by design can selectively self-assemble at the graphite/liquid interface into either face-on or edge-on monolayer-thick architectures. The former supramolecular arrangement consists of two-dimensional planar networks based on hydrogen bonding among adjacent molecules whereas the latter relies on columnar assembly generated through intermolecular van der Waals interactions. Scanning Tunneling Microscopy (STM) at the solid-liquid interface has been corroborated by cyclic voltammetry measurements and assessed by theoretical calculations to gain multiscale insight into the arrangement of the molecule with respect to the basal plane of the surface. The STM analysis allowed the visualization of these assemblies with a sub-nanometer resolution, and cyclic voltammetry measurements provided direct evidence of the interactions of porphyrin and ferrocene with the graphite surface and offered also insight into the dynamics within the face-on and edge-on assemblies. The experimental findings were supported by theoretical calculations to shed light on the electronic and other physical properties of both assemblies. The capability to engineer the functional nanopatterns through self-assembly of porphyrins containing ferrocene units is a key step toward the bottom-up construction of multifunctional molecular nanostructures and nanodevices.Tuning the intermolecular interactions among suitably designed molecules forming highly ordered self-assembled monolayers is a viable approach to

  10. Graphite Technology Development Plan

    SciTech Connect

    W. Windes; T. Burchell; M.Carroll

    2010-10-01

    The Next Generation Nuclear Plant (NGNP) will be a helium-cooled High Temperature Gas Reactor (HTGR) with a large graphite core. Graphite physically contains the fuel and comprises the majority of the core volume. Graphite has been used effectively as a structural and moderator material in both research and commercial high-temperature gas-cooled reactors. This development has resulted in graphite being established as a viable structural material for HTGRs. While the general characteristics necessary for producing nuclear grade graphite are understood, historical “nuclear” grades no longer exist. New grades must be fabricated, characterized, and irradiated to demonstrate that current grades of graphite exhibit acceptable non-irradiated and irradiated properties upon which the thermomechanical design of the structural graphite in NGNP is based. This Technology Development Plan outlines the research and development (R&D) activities and associated rationale necessary to qualify nuclear grade graphite for use within the NGNP reactor.

  11. Design detail verification tests for a lightly loaded open-corrugation graphite-epoxy cylinder

    NASA Technical Reports Server (NTRS)

    Davis, R. C.; Starnes, J. H., Jr.

    1982-01-01

    Flat corrugated graphite-epoxy panels were tested in compression to verify selected design details of a ring-stiffened cylinder that was designed to support an axial compressive load of 157.6 kN/m without buckling. Three different sizes of subcomponent panels, with the same basic corrugation geometry, were tested: (1) 60.96-cm-long by 45.72-cm-wide panels to evaluate the local buckling strength of the shell wall design; (2) 91.44-cm-long by 45.72-cm-wide panels to evaluate a longitudinal joint and the load-introduction method; and (3) 254.0-cm-long by 91.44-cm-wide panels with four simulated-ring stiffeners to evaluate the ring-attachment method. The test results indicate that the modified shell-wall design, the longitudinal joint, the load-introduction method, and the stiffener-attachment method for the proposed cylinder have adequate strength to support the design load.

  12. Molecular design driving tetraporphyrin self-assembly on graphite: a joint STM, electrochemical and computational study.

    PubMed

    El Garah, M; Santana Bonilla, A; Ciesielski, A; Gualandi, A; Mengozzi, L; Fiorani, A; Iurlo, M; Marcaccio, M; Gutierrez, R; Rapino, S; Calvaresi, M; Zerbetto, F; Cuniberti, G; Cozzi, P G; Paolucci, F; Samorì, P

    2016-07-14

    Tuning the intermolecular interactions among suitably designed molecules forming highly ordered self-assembled monolayers is a viable approach to control their organization at the supramolecular level. Such a tuning is particularly important when applied to sophisticated molecules combining functional units which possess specific electronic properties, such as electron/energy transfer, in order to develop multifunctional systems. Here we have synthesized two tetraferrocene-porphyrin derivatives that by design can selectively self-assemble at the graphite/liquid interface into either face-on or edge-on monolayer-thick architectures. The former supramolecular arrangement consists of two-dimensional planar networks based on hydrogen bonding among adjacent molecules whereas the latter relies on columnar assembly generated through intermolecular van der Waals interactions. Scanning Tunneling Microscopy (STM) at the solid-liquid interface has been corroborated by cyclic voltammetry measurements and assessed by theoretical calculations to gain multiscale insight into the arrangement of the molecule with respect to the basal plane of the surface. The STM analysis allowed the visualization of these assemblies with a sub-nanometer resolution, and cyclic voltammetry measurements provided direct evidence of the interactions of porphyrin and ferrocene with the graphite surface and offered also insight into the dynamics within the face-on and edge-on assemblies. The experimental findings were supported by theoretical calculations to shed light on the electronic and other physical properties of both assemblies. The capability to engineer the functional nanopatterns through self-assembly of porphyrins containing ferrocene units is a key step toward the bottom-up construction of multifunctional molecular nanostructures and nanodevices. PMID:27376633

  13. Design Allowables Test Program, Celion 3000/PMR-15 and Celion 6000/PMR-15, Graphite/Polyimide Composites

    NASA Technical Reports Server (NTRS)

    Cushman, J. B.; Mccleskey, S. F.

    1982-01-01

    A design allowables test program was conducted on Celion 3000/PRM-15 and Celion 6000/PMR-15 graphite/polyimide composite to establish material performance over a 116 K (-250 F) to 589 K (600 F) temperature range. Effects of aging, thermal cycling and moisture were also evaluated. Tension, compression and in plane shear properties were determined for uniaxial, pseudoisotropic and +45 laminates. Test results show sufficient strength and stiffness to substantiate graphite/polyimide composites as an acceptable structural material for high temperature structural applications.

  14. Design of the Next Generation Nuclear Plant Graphite Creep Experiments for Irradiation in the Advanced Test Reactor

    SciTech Connect

    S. Blaine Grover

    2009-05-01

    The United States Department of Energy’s Next Generation Nuclear Plant (NGNP) Program will be irradiating six gas reactor graphite creep experiments in the Advanced Test Reactor (ATR) located at the Idaho National Laboratory (INL). The ATR has a long history of irradiation testing in support of reactor development and the INL has been designated as the new United States Department of Energy’s lead laboratory for nuclear energy development. The ATR is one of the world’s premiere test reactors for performing long term, high flux, and/or large volume irradiation test programs. These graphite irradiations are being accomplished to support development of the next generation reactors in the United States. The graphite experiments will be irradiated over the next six to eight years to support development of a graphite irradiation performance data base on the new nuclear grade graphites now available for use in high temperature gas reactors. The goals of the irradiation experiments are to obtain irradiation performance data at different temperatures and loading conditions to support design of the Next Generation Nuclear Plant Very High Temperature Gas Reactor, as well as other future gas reactors. The experiments will each consist of a single capsule that will contain seven separate stacks of graphite specimens. Six of the specimen stacks will have half of their graphite specimens under a compressive load, while the other half of the specimens will not be subjected to a compressive load during irradiation. The six stacks will be organized into pairs with a different compressive load being applied to the top half of each pair of specimen stacks. The seventh stack will not have a compressive load on the graphite specimens during irradiation. The specimens will be irradiated in an inert sweep gas atmosphere with on-line temperature and compressive load monitoring and control. There will also be the capability of sampling the sweep gas effluent to determine if any

  15. Design, fabrication and test of graphite/polyimide composite joints and attachments for advanced aerospace vehicles

    NASA Technical Reports Server (NTRS)

    Barclay, D. L.

    1980-01-01

    Results of an experimental program to develop several types of graphite/polyimide (GR/PI) bonded and bolted joints for lightly loaded flight components for advanced space transportation systems and high speed aircraft are presented. Tasks accomplished include: a literature survey; design of static discriminator specimens; design allowables testing; fabrication of test panels and specimens; small specimen testing; and standard joint testing. Detail designs of static discriminator specimens for each of the four major attachment types are presented. Test results are given for the following: (1) transverse tension of Celion 3000/PMR-15 laminate; (2) net tension of a laminate for both a loaded and unloaded bolt hole; (3) comparative testing of bonded and co-cured doublers along with pull-off tests of single and double bonded angles; (4) single lap shear tests, transverse tension and coefficient of thermal expansion tests of A7F (LARC-13 amide-imide modified) adhesive; and (5) tension tests of standard single lap, double lap, and symmetric step lap bonded joints. Also, included are results of a finite element analysis of a single lap bonded composite joint.

  16. Material Based Structure Design: Numerical Analysis Thermodynamic Response of Thermal Pyrolytic Graphite /Al Sandwich Composites

    NASA Astrophysics Data System (ADS)

    Wang, Junxia; Yan, Shilin; Yu, Dingshan

    2016-06-01

    Amine-grafted multiwalled carbon nanotubes (MWCNTs) based thermally conductive adhesive (TCA) was studied in the previous paper and applied here in thermal pyrolytic graphite (TPG)/Al radiator due to its high thermal conductivity, toughness and cohesiveness. In this paper, in an attempt to confirm the application of TCA to TPG/Al sandwich radiator, the thermodynamic response in TPG/Al sandwich composites associated with key material properties and structural design was investigated using finite element simulation with commercial available ANSYS software. The induced thermal stress in TCA layer is substantial due to the thermal expansion mismatch between Al plate and TPG. The maximum thermal stress is located near the edge of TCA layer with the von Mises stress value of 4.02 MPa and the shear stress value of 1.66 MPa. The reasonable adjustment of physical-mechanical properties including thermal conductivity, thermal expansion, Young,s modulus and the thickness of TCA layer, Al plate and TPG are beneficial for reducing the temperature of the top surface of the upper skin and their effects on the reduction of thermal structural response in some ways. These findings will highlight the structural optimization of TPG/Al radiator for future application.

  17. Design, fabrication and performance of small, graphite electrode, multistage depressed collectors with 200-W, CW, 8- to 18-GHz traveling-wave tubes

    NASA Technical Reports Server (NTRS)

    Ebihara, Ben T.; Ramins, Peter

    1987-01-01

    Small multistage depressed collectors (MDC's) which used pyrolytic graphite, ion-beam-textured pyrolytic graphite, and isotropic graphite electrodes were designed, fabricated, and evaluated in conjuntion with 200-W, continuous wave (CW), 8- to 18-GHz traveling-wave tubes (TWT's). The design, construction, and performance of the MDC's are described. The bakeout performance of the collectors, in terms of gas evolution, was indistinguishable from that of typical production tubes with copper collectors. However, preliminary results indicate that some additional radiofrequency (RF) and dc beam processing time (and/or longer or higher temperature bakeouts) may be needed beyond that of typical copper electrode collectors. This is particularly true for pyrolytic graphite electrodes and for TWT's without appendage ion pumps. Extended testing indicated good long-term stability of the textured pyrolytic graphite and isotropic graphite electrode surfaces. The isotropic graphite in particular showed considerable promise as an MDC electrode material because of its high purity, low cost, simple construction, potential for very compact overall size, and relatively low secondary electron emission yield characteristics in the as-machined state. However, considerably more testing experience is required before definitive conclusions on its suitability for electronic countermeasure systems and space TWT's can be made.

  18. Graphite-based photovoltaic cells

    DOEpatents

    Lagally, Max; Liu, Feng

    2010-12-28

    The present invention uses lithographically patterned graphite stacks as the basic building elements of an efficient and economical photovoltaic cell. The basic design of the graphite-based photovoltaic cells includes a plurality of spatially separated graphite stacks, each comprising a plurality of vertically stacked, semiconducting graphene sheets (carbon nanoribbons) bridging electrically conductive contacts.

  19. Self-assembled monolayers of shape-persistent macrocycles on graphite: interior design and conformational polymorphism

    PubMed Central

    Vollmeyer, Joscha; Eberhagen, Friederike; Höger, Sigurd

    2014-01-01

    Summary Three shape-persistent naphthylene–phenylene–acetylene macrocycles of identical backbone structures and extraannular substitution patterns but different (empty, apolar, polar) nanopore fillings are self-assembled at the solid/liquid interface of highly oriented pyrolytic graphite and 1,2,4-trichlorobenzene. Submolecularly resolved images of the resulting two-dimensional (2D) crystalline monolayer patterns are obtained by in situ scanning tunneling microscopy. A concentration-dependent conformational polymorphism is found, and open and more dense packing motifs are observed. For all three compounds alike lattice parameters are found, therefore the intermolecular macrocycle distances are mainly determined by their size and symmetry. This is an excellent example that the graphite acts as a template for the macrocycle organization independent from their specific interior. PMID:25550743

  20. Design, fabrication, and test of a Graphite/Epoxy Metering Shell (GEMS). [for the large space telescope

    NASA Technical Reports Server (NTRS)

    1975-01-01

    A program to design, fabricate and test a dimensionally stable metering structure in support of the large space telescope (LST) program is discussed. Graphite/epoxy was the material selected as the only viable candidate material which can meet the stringent thermal expansion criteria of the LST. A metering shell was designed and fabricated, with emphasis on dimensional stability in conjunction with low cost. Thermal expansion test coupons extracted from the layups of the skin panels indicated the attainment of a coefficient of thermal expansion of 0.0666 micrometers/m K. Subsequent thermal vacuum chamber tests on the complete metering shell demonstrated an expansion of the 2.95-meter overall length of 0.27 micrometers/K. Static and dynamics tests, which demonstrated adequacy with respect to limit loads and stiffness, were also accomplished.

  1. GRAPHITE EXTRUSIONS

    DOEpatents

    Benziger, T.M.

    1959-01-20

    A new lubricant for graphite extrusion is described. In the past, graphite extrusion mixtures have bcen composed of coke or carbon black, together with a carbonaceous binder such as coal tar pitch, and a lubricant such as petrolatum or a colloidal suspension of graphite in glycerin or oil. Sinee sueh a lubricant is not soluble in, or compatible with the biiider liquid, such mixtures were difficult to extrude, and thc formed pieees lacked strength. This patent teaches tbe use of fatty acids as graphite extrusion lubricants and definite improvemcnts are realized thereby since the fatty acids are soluble in the binder liquid.

  2. Graphite Technology Development Plan

    SciTech Connect

    W. Windes; T. Burchell; R. Bratton

    2007-09-01

    This technology development plan is designed to provide a clear understanding of the research and development direction necessary for the qualification of nuclear grade graphite for use within the Next Generation Nuclear Plant (NGNP) reactor. The NGNP will be a helium gas cooled Very High Temperature Reactor (VHTR) with a large graphite core. Graphite physically contains the fuel and comprises the majority of the core volume. Considerable effort will be required to ensure that the graphite performance is not compromised during operation. Based upon the perceived requirements the major data needs are outlined and justified from the perspective of reactor design, reatcor performance, or the reactor safety case. The path forward for technology development can then be easily determined for each data need. How the data will be obtained and the inter-relationships between the experimental and modeling activities will define the technology development for graphite R&D. Finally, the variables affecting this R&D program are discussed from a general perspective. Factors that can significantly affect the R&D program such as funding, schedules, available resources, multiple reactor designs, and graphite acquisition are analyzed.

  3. Graphite technology development plan

    SciTech Connect

    1986-07-01

    This document presents the plan for the graphite technology development required to support the design of the 350 MW(t) Modular HTGR within the US National Gas-Cooled Reactor Program. Besides descriptions of the required technology development, cost estimates, and schedules, the plan also includes the associated design functions and design requirements.

  4. Design, fabrication and test of graphite/polyimide composite joints and attachments for advanced aerospace vehicles

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Principal program activities dealt with the literature survey, design of joint concepts, assessment of GR/PI material quality, fabrication of test panels and specimens, and small specimen testing. Bonded and bolted designs are presented for each of the four major attachment types. Quality control data are presented for prepreg Lots 2W4651 and 3W2020. Preliminary design allowables test results for tension tests and compression tests of laminates are also presented.

  5. Design, fabrication and test of graphite/polyimide composite joints and attachments for advanced aerospace vehicles

    NASA Technical Reports Server (NTRS)

    Skoumal, D. E.

    1980-01-01

    Bonded and bolted designs are presented for each of four major attachment types. Prepreg processing problems are discussed and quality control data are given for lots 2W4604, 2W4632 and 2W4643. Preliminary design allowables test results for tension tests and compression tests of laminates are included. The final small specimen test matrix is defined and the configuration of symmetric step-lap joint specimens are shown. Finite element modeling studies of a double lap joint were performed to evaluate the number of elements required through the adhesive thickness to assess effects of various joint parameters on stress distributions. Results of finite element analyses assessing the effect of an adhesive fillet on the stress distribution in a double lap joint are examined.

  6. Baseline Graphite Characterization: First Billet

    SciTech Connect

    Mark C. Carroll; Joe Lords; David Rohrbaugh

    2010-09-01

    The Next Generation Nuclear Plant Project Graphite Research and Development program is currently establishing the safe operating envelope of graphite core components for a very high temperature reactor design. To meet this goal, the program is generating the extensive amount of quantitative data necessary for predicting the behavior and operating performance of the available nuclear graphite grades. In order determine the in-service behavior of the graphite for the latest proposed designs, two main programs are underway. The first, the Advanced Graphite Creep (AGC) program, is a set of experiments that are designed to evaluate the irradiated properties and behavior of nuclear grade graphite over a large spectrum of temperatures, neutron fluences, and compressive loads. Despite the aggressive experimental matrix that comprises the set of AGC test runs, a limited amount of data can be generated based upon the availability of space within the Advanced Test Reactor and the geometric constraints placed on the AGC specimens that will be inserted. In order to supplement the AGC data set, the Baseline Graphite Characterization program will endeavor to provide supplemental data that will characterize the inherent property variability in nuclear-grade graphite without the testing constraints of the AGC program. This variability in properties is a natural artifact of graphite due to the geologic raw materials that are utilized in its production. This variability will be quantified not only within a single billet of as-produced graphite, but also from billets within a single lot, billets from different lots of the same grade, and across different billets of the numerous grades of nuclear graphite that are presently available. The thorough understanding of this variability will provide added detail to the irradiated property data, and provide a more thorough understanding of the behavior of graphite that will be used in reactor design and licensing. This report covers the

  7. Design, fabrication, and performance of brazed, graphite electrode, multistage depressed collectors with 500-W, continuous wave, 4.8- to 9.6-GHz traveling-wave tubes

    NASA Technical Reports Server (NTRS)

    Ramins, Peter; Ebihara, Ben

    1989-01-01

    A small, isotropic graphite electrode, multistage depressed collector (MDC) was designed, fabricated, and evaluated in conjunction with a 500-W, continuous wave (CW), 4.8- to 9.6-GHz traveling-wave tube (TWT). The carbon electrode surfaces were used to improve the TWT overall efficiency by minimizing the secondary electron emission losses in the MDC. The design and fabrication of the brazed graphite MDC assembly are described. The brazing technique, which used copper braze filler metal, is compatible with both vacuum and the more commonly available hydrogen atmosphere brazing furnaces. The TWT and graphite electrode MCC bakeout, processing, and outgassing characteristics were evaluated and found to be comparable to TWT's equipped with copper electrode MDC's. The TWT and MDC performance was optimized for broadband CW operation at saturation. The average radiofrequency (RF), overall, and MDC efficiencies were 14.9, 46.4, and 83.6 percent, respectively, across the octave operating band. A 1500-hr CW test, conducted without the use of an appendage ion pump, showed no gas buildup and excellent stability of the electrode surfaces.

  8. AGC-2 Graphite Preirradiation Data Package

    SciTech Connect

    David Swank; Joseph Lord; David Rohrbaugh; William Windes

    2012-10-01

    The NGNP Graphite R&D program is currently establishing the safe operating envelope of graphite core components for a Very High Temperature Reactor (VHTR) design. The program is generating quantitative data necessary for predicting the behavior and operating performance of the new nuclear graphite grades. To determine the in-service behavior of the graphite for pebble bed and prismatic designs, the Advanced Graphite Creep (AGC) experiment is underway. This experiment is examining the properties and behavior of nuclear grade graphite over a large spectrum of temperatures, neutron fluences and compressive loads. Each experiment consists of over 400 graphite specimens that are characterized prior to irradiation and following irradiation. Six experiments are planned with the first, AGC-1, currently being irradiated in the Advanced Test Reactor (ATR) and pre-irradiation characterization of the second, AGC-2, completed. This data package establishes the readiness of 512 specimens for assembly into the AGC-2 capsule.

  9. Thermally exfoliated graphite oxide

    NASA Technical Reports Server (NTRS)

    Prud'Homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor); Abdala, Ahmed (Inventor)

    2011-01-01

    A modified graphite oxide material contains a thermally exfoliated graphite oxide with a surface area of from about 300 sq m/g to 2600 sq m/g, wherein the thermally exfoliated graphite oxide displays no signature of the original graphite and/or graphite oxide, as determined by X-ray diffraction.

  10. Bridged graphite oxide materials

    NASA Technical Reports Server (NTRS)

    Herrera-Alonso, Margarita (Inventor); McAllister, Michael J. (Inventor); Aksay, Ilhan A. (Inventor); Prud'homme, Robert K. (Inventor)

    2010-01-01

    Bridged graphite oxide material comprising graphite sheets bridged by at least one diamine bridging group. The bridged graphite oxide material may be incorporated in polymer composites or used in adsorption media.

  11. AGC-3 Graphite Preirradiation Data Analysis Report

    SciTech Connect

    William Windes; David Swank; David Rohrbaugh; Joseph Lord

    2013-09-01

    This report describes the specimen loading order and documents all pre-irradiation examination material property measurement data for the graphite specimens contained within the third Advanced Graphite Capsule (AGC-3) irradiation capsule. The AGC-3 capsule is third in six planned irradiation capsules comprising the Advanced Graphite Creep (AGC) test series. The AGC test series is used to irradiate graphite specimens allowing quantitative data necessary for predicting the irradiation behavior and operating performance of new nuclear graphite grades to be generated which will ascertain the in-service behavior of the graphite for pebble bed and prismatic Very High Temperature Reactor (VHTR) designs. The general design of AGC-3 test capsule is similar to the AGC-2 test capsule, material property tests were conducted on graphite specimens prior to loading into the AGC-3 irradiation assembly. However the 6 major nuclear graphite grades in AGC-2 were modified; two previous graphite grades (IG-430 and H-451) were eliminated and one was added (Mersen’s 2114 was added). Specimen testing from three graphite grades (PCEA, 2114, and NBG-17) was conducted at Idaho National Laboratory (INL) and specimen testing for two grades (IG-110 and NBG-18) were conducted at Oak Ridge National Laboratory (ORNL) from May 2011 to July 2013. This report also details the specimen loading methodology for the graphite specimens inside the AGC-3 irradiation capsule. The AGC-3 capsule design requires "matched pair" creep specimens that have similar dose levels above and below the neutron flux profile mid-plane to provide similar specimens with and without an applied load. This document utilized the neutron flux profile calculated for the AGC-3 capsule design, the capsule dimensions, and the size (length) of the selected graphite and silicon carbide samples to create a stacking order that can produce "matched pairs" of graphite samples above and below the AGC-3 capsule elevation mid-point to

  12. NGNP Graphite Selection and Acquisition Strategy

    SciTech Connect

    Burchell, T.; Bratton, R.; Windes, W.

    2007-09-30

    The nuclear graphite (H-451) previously used in the United States for High-Temperature Reactors (HTRs) is no longer available. New graphites have been developed and are considered suitable candidates for the Next-Generation Nuclear Plant (NGNP). A complete properties database for these new, available, candidate grades of graphite must be developed to support the design and licensing of NGNP core components. Data are required for the physical, mechanical (including radiation-induced creep), and oxidation properties of graphites. Moreover, the data must be statistically sound and take account of in-billet, between billets, and lot-to-lot variations of properties. These data are needed to support the ongoing development1 of the risk-derived American Society of Mechanical Engineers (ASME) graphite design code (a consensus code being prepared under the jurisdiction of the ASME by gas-cooled reactor and NGNP stakeholders including the vendors). The earlier Fort St. Vrain design of High-Temperature Reactor (HTRs) used deterministic performance models for H-451, while the NGNP will use new graphite grades and risk-derived (probabilistic) performance models and design codes, such as that being developed by the ASME. A radiation effects database must be developed for the currently available graphite materials, and this requires a substantial graphite irradiation program. The graphite Technology Development Plan (TDP)2 describes the data needed and the experiments planned to acquire these data in a timely fashion to support NGNP design, construction, and licensing. The strategy for the selection of appropriate grades of graphite for the NGNP is discussed here. The final selection of graphite grades depends upon the chosen reactor type and vendor because the reactor type (pebble bed or prismatic block) has a major influence on the graphite chosen by the designer. However, the time required to obtain the needed irradiation data for the selected NGNP graphite is sufficiently

  13. Preparation of graphitic articles

    DOEpatents

    Phillips, Jonathan; Nemer, Martin; Weigle, John C.

    2010-05-11

    Graphitic structures have been prepared by exposing templates (metal, metal-coated ceramic, graphite, for example) to a gaseous mixture that includes hydrocarbons and oxygen. When the template is metal, subsequent acid treatment removes the metal to yield monoliths, hollow graphitic structures, and other products. The shapes of the coated and hollow graphitic structures mimic the shapes of the templates.

  14. Inhibition of Oxidation in Nuclear Graphite

    SciTech Connect

    Phil Winston; James W. Sterbentz; William E. Windes

    2013-10-01

    Graphite is a fundamental material of high temperature gas cooled nuclear reactors, providing both structure and neutron moderation. Its high thermal conductivity, chemical inertness, thermal heat capacity, and high thermal structural stability under normal and off normal conditions contribute to the inherent safety of these reactor designs. One of the primary safety issues for a high temperature graphite reactor core is the possibility of rapid oxidation of the carbon structure during an off normal design basis event where an oxidizing atmosphere (air ingress) can be introduced to the hot core. Although the current Generation IV high temperature reactor designs attempt to mitigate any damage caused by a postualed air ingress event, the use of graphite components that inhibit oxidation is a logical step to increase the safety of these reactors. Recent experimental studies of graphite containing between 5.5 and 7 wt% boron carbide (B4C) indicate that oxidation is dramatically reduced even at prolonged exposures at temperatures up to 900°C. The proposed addition of B4C to graphite components in the nuclear core would necessarily be enriched in B-11 isotope in order to minimize B-10 neutron absorption and graphite swelling. The enriched boron can be added to the graphite during billet fabrication. Experimental oxidation rate results and potential applications for borated graphite in nuclear reactor components will be discussed.

  15. Chapter 20: Graphite

    SciTech Connect

    Burchell, Timothy D

    2012-01-01

    Graphite is truly a unique material. Its structure, from the nano- to the millimeter scale give it remarkable properties that lead to numerous and diverse applications. Graphite bond anisotropy, with strong in-plane covalent bonds and weak van der Waals type bonding between the planes, gives graphite its unique combination of properties. Easy shear of the crystal, facilitated by weak interplaner bonds allows graphite to be used as a dry lubricant, and is responsible for the substances name! The word graphite is derived from the Greek to write because of graphites ability to mark writing surfaces. Moreover, synthetic graphite contains within its structure, porosity spanning many orders of magnitude in size. The thermal closure of these pores profoundly affects the properties for example, graphite strength increases with temperature to temperatures in excess of 2200 C. Consequently, graphite is utilized in many high temperature applications. The basic physical properties of graphite are reviewed here. Graphite applications include metallurgical; (aluminum and steel production), single crystal silicon production, and metal casting; electrical (motor brushes and commutators); mechanical (seals, bearings and bushings); and nuclear applications, (see Chapter 91, Nuclear Graphite). Here we discuss the structure, manufacture, properties, and applications of Graphite.

  16. Pyrolytic graphite collector development program

    NASA Technical Reports Server (NTRS)

    Wilkins, W. J.

    1982-01-01

    Pyrolytic graphite promises to have significant advantages as a material for multistage depressed collector electrodes. Among these advantages are lighter weight, improved mechanical stiffness under shock and vibration, reduced secondary electron back-streaming for higher efficiency, and reduced outgassing at higher operating temperatures. The essential properties of pyrolytic graphite and the necessary design criteria are discussed. This includes the study of suitable electrode geometries and methods of attachment to other metal and ceramic collector components consistent with typical electrical, thermal, and mechanical requirements.

  17. The Treatment of PPCP-Containing Sewage in an Anoxic/Aerobic Reactor Coupled with a Novel Design of Solid Plain Graphite-Plates Microbial Fuel Cell

    PubMed Central

    Chang, Yi-Tang; Yang, Chu-Wen; Chang, Yu-Jie; Chang, Ting-Chieh; Wei, Da-Jiun

    2014-01-01

    Synthetic sewage containing high concentrations of pharmaceuticals and personal care products (PPCPs, mg/L level) was treated using an anoxic/aerobic (A/O) reactor coupled with a microbial fuel cell (MFC) at hydraulic retention time (HRT) of 8 h. A novel design of solid plain graphite plates (SPGRPs) was used for the high surface area biodegradation of the PPCP-containing sewage and for the generation of electricity. The average CODCr and total nitrogen removal efficiencies achieved were 97.20% and 83.75%, respectively. High removal efficiencies of pharmaceuticals, including acetaminophen, ibuprofen, and sulfamethoxazole, were also obtained and ranged from 98.21% to 99.89%. A maximum power density of 532.61 mW/cm2 and a maximum coulombic efficiency of 25.20% were measured for the SPGRP MFC at the anode. Distinct differences in the bacterial community were presented at various locations including the mixed liquor suspended solids and biofilms. The bacterial groups involved in PPCP biodegradation were identified as Dechloromonas spp., Sphingomonas sp., and Pseudomonas aeruginosa. This design, which couples an A/O reactor with a novel design of SPGRP MFC, allows the simultaneous removal of PPCPs and successful electricity production. PMID:25197659

  18. AGC-2 Graphite Preirradiation Data Analysis Report

    SciTech Connect

    William Windes; W. David Swank; David Rohrbaugh; Joseph Lord

    2013-08-01

    This report described the specimen loading order and documents all pre-irradiation examination material property measurement data for the graphite specimens contained within the second Advanced Graphite Capsule (AGC-2) irradiation capsule. The AGC-2 capsule is the second in six planned irradiation capsules comprising the Advanced Graphite Creep (AGC) test series. The AGC test series is used to irradiate graphite specimens allowing quantitative data necessary for predicting the irradiation behavior and operating performance of new nuclear graphite grades to be generated which will ascertain the in-service behavior of the graphite for pebble bed and prismatic Very High Temperature Reactor (VHTR) designs. Similar to the AGC-1 specimen pre-irradiation examination report, material property tests were conducted on specimens from 18 nuclear graphite types but on an increased number of specimens (512) prior to loading into the AGC-2 irradiation assembly. All AGC-2 specimen testing was conducted at Idaho National Laboratory (INL) from October 2009 to August 2010. This report also details the specimen loading methodology for the graphite specimens inside the AGC-2 irradiation capsule. The AGC-2 capsule design requires “matched pair” creep specimens that have similar dose levels above and below the neutron flux profile mid-plane to provide similar specimens with and without an applied load. This document utilized the neutron flux profile calculated for the AGC-2 capsule design, the capsule dimensions, and the size (length) of the selected graphite and silicon carbide samples to create a stacking order that can produce “matched pairs” of graphite samples above and below the AGC-2 capsule elevation mid-point to provide specimens with similar neutron dose levels.

  19. Multiaxial graphite test specimen

    SciTech Connect

    1988-09-01

    A multiaxial test program is to be conducted by Oak Ridge National Laboratory (ORNL) on the core component graphite. The objectives of the tests are to obtain failure data under uniaxial and biaxial states of stress in order to construct a failure surface in a two-dimensional stress space. These data will be used in verifying the accuracy of the maximum stress failure theory being proposed for use in designing the core graphite components. Tubular specimens are proposed to be used and are either loaded axially and/or subjected to internal pressure. This report includes a study on three specimen configurations. The conclusions of that study indicate that an elliptical transition geometry procedures the smallest discontinuity effects. Several loading combustions were studied using the elliptical transition specimen. The primary purpose is to establish the location of the highest stress state and its relation to the gage section for all of the loading conditions. The tension/internal pres sure loading condition (1:1) indicated that the high stress area is just outside the gage section but still should be acceptable. 5 refs., 18 figs.

  20. Verification of computer-aided designs of traveling-wave tubes utilizing novel dynamic refocusers and graphite electrodes for the multistage depressed collector

    NASA Technical Reports Server (NTRS)

    Ramins, P.; Kosmahl, H. G.; Force, D. A.; Palmer, R. W.; Dayton, J. A., Jr.

    1985-01-01

    A computational procedure for the design of TWT-refocuser-MDC systems was used to design a short dynamic refocusing system and highly efficient four-stage depressed collector for a 200-W, 8- to 18-GHz, TWT. The computations were carried out with advanced, multidimensional computer programs which model the electron beam as a series of disks of charge and follow their trajectories from the RF input of the TWT, through the slow-wave structure and refocusing section, to their points of impact in the depressed collector. Secondary emission losses in the MDC were treated semi-quantitatively by injecting a representative beam of secondary electrons into the MDC analysis at the point of impact of each primary beam. A comparison of computed and measured TWT and MDC performance showed very good agreement. The electrodes of the MDC were fabricated from a particular form of isotropic graphite that was selected for its low secondary electron yield, ease of machinability, and vacuum properties. This MDC was tested (at CW) for more than 1000 hr with negligible degradation in TWT and MDC performances.

  1. AGC-2 Graphite Pre-irradiation Data Package

    SciTech Connect

    David Swank; Joseph Lord; David Rohrbaugh; William Windes

    2010-08-01

    The NGNP Graphite R&D program is currently establishing the safe operating envelope of graphite core components for a Very High Temperature Reactor (VHTR) design. The program is generating quantitative data necessary for predicting the behavior and operating performance of the new nuclear graphite grades. To determine the in-service behavior of the graphite for pebble bed and prismatic designs, the Advanced Graphite Creep (AGC) experiment is underway. This experiment is examining the properties and behavior of nuclear grade graphite over a large spectrum of temperatures, neutron fluences and compressive loads. Each experiment consists of over 400 graphite specimens that are characterized prior to irradiation and following irradiation. Six experiments are planned with the first, AGC-1, currently being irradiated in the Advanced Test Reactor (ATR) and pre-irradiation characterization of the second, AGC-2, completed. This data package establishes the readiness of 512 specimens for assembly into the AGC-2 capsule.

  2. THE NEXT GENERATION NUCLEAR PLANT GRAPHITE PROGRAM

    SciTech Connect

    William E. Windes; Timothy D. Burchell; Robert L. Bratton

    2008-09-01

    Developing new nuclear grades of graphite used in the core of a High Temperature Gas-cooled Reactor (HTGR) is one of the critical development activities being pursued within the Next Generation Nuclear Plant (NGNP) program. Graphite’s thermal stability (in an inert gas environment), high compressive strength, fabricability, and cost effective price make it an ideal core structural material for the HTGR reactor design. While the general characteristics necessary for producing nuclear grade graphite are understood, historical “nuclear” grades no longer exist. New grades must be fabricated, characterized, and irradiated to demonstrate that current grades of graphite exhibit acceptable non-irradiated and irradiated properties upon which the thermo-mechanical design of the structural graphite in NGNP is based. The NGNP graphite R&D program has selected a handful of commercially available types for research and development activities necessary to qualify this nuclear grade graphite for use within the NGNP reactor. These activities fall within five primary areas; 1) material property characterization, 2) irradiated material property characterization, 3) modeling, and 4) ASTM test development, and 5) ASME code development efforts. Individual research and development activities within each area are being pursued with the ultimate goal of obtaining a commercial operating license for the nuclear graphite from the US NRC.

  3. Radiation Effects in Graphite

    SciTech Connect

    Burchell, Timothy D

    2012-01-01

    The requirements for a solid moderator are reviewed and the reasons that graphite has become the solid moderator of choice discussed. The manufacture and properties of some currently available near-isotropic and isotropic grades are described. The major features of a graphite moderated reactors are briefly outlined. Displacement damage and the induced structural and dimensional changes in graphite are described. Recent characterization work on nano-carbons and oriented pyrolytic graphites that have shed new light on graphite defect structures are reviewed, and the effect of irradiation temperature on the defect structures is highlighted. Changes in the physical properties of nuclear graphite caused by neutron irradiation are reported. Finally, the importance of irradiation induced creep is presented, along with current models and their deficiencies.

  4. Thermal and flammability characterization of graphite composites

    NASA Technical Reports Server (NTRS)

    Kourtides, D. A.

    1986-01-01

    Thermal, mechanical, and flammability properties of graphite composites fabricated with XU71775/H795, a bismaleimide/vinyl-polystyrylpyridine formulation; H795, a bismaleimide; Cycom 6162, a phenolic; and PSP 6022M, a polystyrylpyridine and two types of graphite reinforcement were evaluated and compared with a composite made with an epoxy resin as a matrix. The measured properties included limiting-oxygen index, smoke evolution, thermal degradation products, total-heat release, heat-release rates, mass loss, flame spread, ignition resistance, thermogravimetric analysis, and selected mechanical properties. It was found that the combination of XU71775/H795 with the graphite tape was the optimum design giving the lowest heat release rate.

  5. Producing graphite with desired properties

    NASA Technical Reports Server (NTRS)

    Dickinson, J. M.; Imprescia, R. J.; Reiswig, R. D.; Smith, M. C.

    1971-01-01

    Isotropic or anisotropic graphite is synthesized with precise control of particle size, distribution, and shape. The isotropic graphites are nearly perfectly isotropic, with thermal expansion coefficients two or three times those of ordinary graphites. The anisotropic graphites approach the anisotropy of pyrolytic graphite.

  6. Oxidation Resistant Graphite Studies

    SciTech Connect

    W. Windes; R. Smith

    2014-07-01

    The Very High Temperature Reactor (VHTR) Graphite Research and Development Program is investigating doped nuclear graphite grades exhibiting oxidation resistance. During a oxygen ingress accident the oxidation rates of the high temperature graphite core region would be extremely high resulting in significant structural damage to the core. Reducing the oxidation rate of the graphite core material would reduce the structural effects and keep the core integrity intact during any air-ingress accident. Oxidation testing of graphite doped with oxidation resistant material is being conducted to determine the extent of oxidation rate reduction. Nuclear grade graphite doped with varying levels of Boron-Carbide (B4C) was oxidized in air at nominal 740°C at 10/90% (air/He) and 100% air. The oxidation rates of the boronated and unboronated graphite grade were compared. With increasing boron-carbide content (up to 6 vol%) the oxidation rate was observed to have a 20 fold reduction from unboronated graphite. Visual inspection and uniformity of oxidation across the surface of the specimens were conducted. Future work to determine the remaining mechanical strength as well as graphite grades with SiC doped material are discussed.

  7. Development and evaluation of graphite and boron polyimide composites.

    NASA Technical Reports Server (NTRS)

    Scheck, W. G.; Stuckey, J. M.

    1972-01-01

    This paper covers the development and evaluation of the HT-S/710 graphite/polyimide system and initial evaluations of high modulus graphite and boron reinforced polyimide systems. Detail design properties of the HT-S/710 graphite/polyimide systems, test results of test sheet stringer components, and initial test evaluations of high modulus graphite and boron reinforced polyimide composites are presented. Preliminary design applications utilizing the basic processing and design data from this development program are presented as to their utilization in aircraft and space applications.

  8. Graphite nanoreinforcements in polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Fukushima, Hiroyuki

    , or carbon blacks. The exfoliated graphite flakes reached the percolation threshold at 1.93 wt% (1.13 vol%) in an epoxy system and the resistivity of the composite showed 39 ohm•cm with 7 wt% of exfoliated graphite, which is comparable to the high-grade carbon black based systems. The vapor grown carbon fiber based composites showed higher resistivity at the same filler contents while the conventional carbon fiber composites showed much higher resistivity and percolation threshold. Stress distribution analysis by Finite Element Method revealed the stress concentration condition of composite systems is affected by factors such as shape of the reinforcements, aspect ratio, and geological arrangements. Based on these results, an optimal morphology design of nanocomposite system was proposed. Market research revealed that there is a realistic possibility for applying the new process and material in commercial products and a venture business plan was proposed based on this new technology. The venture plan won "The Most Innovative Design" award at the 2002 Michigan Collegiate Entrepreneur's Conference.

  9. Induction graphitizing furnace acceptance test report

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The induction furnace was designed to provide the controlled temperature and environment required for the post-cure, carbonization and graphitization processes for the fabrication of a fibrous graphite NERVA nozzle extension. The acceptance testing required six tests and a total operating time of 298 hrs. Low temperature mode operations, 120 to 850 C, were completed in one test run. High temperature mode operations, 120 to 2750 C, were completed during five tests.

  10. Graphite/Thermoplastic-Pultrusion Die

    NASA Technical Reports Server (NTRS)

    Wilson, Maywood L.; Frye, Mark W.; Johnson, Gary S.; Stanfield, Clarence E.

    1990-01-01

    Attachment to extruder produces thermoplastic-impregnated graphite tape. Consists of profile die, fiber/resin collimator, and crosshead die body. Die designed to be attached to commercially available extrusion machine capable of extruding high-performance thermoplastics. Simple attachment to commercial extruder enables developers of composites to begin experimenting with large numbers of proprietary resins, fibers, and hybrid composite structures. With device, almost any possible fiber/resin combination fabricated.

  11. Modelling the graphite fracture mechanisms

    SciTech Connect

    Jacquemoud, C.; Marie, S.; Nedelec, M.

    2012-07-01

    In order to define a design criterion for graphite components, it is important to identify the physical phenomena responsible for the graphite fracture, to include them in a more effective modelling. In a first step, a large panel of experiments have been realised in order to build up an important database; results of tensile tests, 3 and 4 point bending tests on smooth and notched specimens have been analysed and have demonstrated an important geometry related effects on the behavior up to fracture. Then, first simulations with an elastic or an elastoplastic bilinear constitutive law have not made it possible to simulate the experimental fracture stress variations with the specimen geometry, the fracture mechanisms of the graphite being at the microstructural scale. That is the reason why a specific F.E. model of the graphite structure has been developed in which every graphite grain has been meshed independently, the crack initiation along the basal plane of the particles as well as the crack propagation and coalescence have been modelled too. This specific model has been used to test two different approaches for fracture initiation: a critical stress criterion and two criteria of fracture mechanic type. They are all based on crystallographic considerations as a global critical stress criterion gave unsatisfactory results. The criteria of fracture mechanic type being extremely unstable and unable to represent the graphite global behaviour up to the final collapse, the critical stress criterion has been preferred to predict the results of the large range of available experiments, on both smooth and notched specimens. In so doing, the experimental observations have been correctly simulated: the geometry related effects on the experimental fracture stress dispersion, the specimen volume effects on the macroscopic fracture stress and the crack propagation at a constant stress intensity factor. In addition, the parameters of the criterion have been related to

  12. Coating method for graphite

    DOEpatents

    Banker, John G.; Holcombe, Jr., Cressie E.

    1977-01-01

    A method of limiting carbon contamination from graphite ware used in induction melting of uranium alloys is provided comprising coating the graphite surface with a suspension of Y.sub.2 O.sub.3 particles in water containing about 1.5 to 4% by weight sodium carboxymethylcellulose.

  13. Coating method for graphite

    DOEpatents

    Banker, J.G.; Holcombe, C.E. Jr.

    1975-11-06

    A method of limiting carbon contamination from graphite ware used in induction melting of uranium alloys is provided. The graphite surface is coated with a suspension of Y/sub 2/O/sub 3/ particles in water containing about 1.5 to 4 percent by weight sodium carboxymethylcellulose.

  14. Thermal neutron scattering in graphite

    NASA Astrophysics Data System (ADS)

    Al-Qasir, Iyad Ibrahim

    Generation IV Very High Temperature Reactor (VHTR) concepts, are graphite moderated and gas cooled thermal spectrum reactors. The characteristics of the low energy (E < 1 eV) neutron spectrum in these reactors will be dictated by the process of neutron slowing-down and thermalization in the graphite moderator. The ability to accurately predict this process in these reactors can have significant neutronic and safety implications. In reactor design calculations, thermal neutron scattering cross section libraries are needed for the prediction of the thermal neutron environment in the core. Currently used libraries (ENDF/B-VII) are a product of the 1960s and remain based on many physical approximations. In addition, these libraries show noticeable discrepancies with experimental data. In this work, investigation of thermal neutron scattering in graphite as a function of temperature was performed. The fundamental input for the calculation of thermal neutron scattering cross sections, i.e., the phonon frequency distribution and/or the dispersion relations, was generated using a modern approach that is based on quantum mechanical electronic structure (ab initio) simulations combined with a lattice dynamics direct method supercell approach. The calculations were performed using the VASP and PHONON codes. The VASP calculations used the local density approximation, and the projector augmented-wave pseudopotential. A supercell of 144 atoms was used; and the integration over the Brillouin zone was confined to a 3x3x4 k-mesh generated by the Monkhorst-Pack scheme. A plane-wave basis set with an energy cutoff of 500 eV was applied. The corresponding dispersion relations, heat capacity, and phonon frequency distribution show excellent agreement with experimental data. Despite the use of the above techniques to produce more accurate input data, the examination of the results indicated persistence of the inconsistencies between calculations and measurements at neutron energies

  15. Method for producing dustless graphite spheres from waste graphite fines

    DOEpatents

    Pappano, Peter J; Rogers, Michael R

    2012-05-08

    A method for producing graphite spheres from graphite fines by charging a quantity of spherical media into a rotatable cylindrical overcoater, charging a quantity of graphite fines into the overcoater thereby forming a first mixture of spherical media and graphite fines, rotating the overcoater at a speed such that the first mixture climbs the wall of the overcoater before rolling back down to the bottom thereby forming a second mixture of spherical media, graphite fines, and graphite spheres, removing the second mixture from the overcoater, sieving the second mixture to separate graphite spheres, charging the first mixture back into the overcoater, charging an additional quantity of graphite fines into the overcoater, adjusting processing parameters like overcoater dimensions, graphite fines charge, overcoater rotation speed, overcoater angle of rotation, and overcoater time of rotation, before repeating the steps until graphite fines are converted to graphite spheres.

  16. Three-dimensional architecture of lithium-anodes made from graphite fibers coated with thin-films of silicon oxycarbide: Design, performance and manufacturability

    NASA Astrophysics Data System (ADS)

    Saleh, Ibrahim; Raj, Rishi

    2016-04-01

    Silicon oxycarbide (SiCO) is an amorphous molecular network of Sisbnd Csbnd O tetrahedra anchored to graphene-like carbon. The graphene forms a three dimensional cellular network with a domain size of ∼5 nm. Therefore nanometer thick films of SiCO grown on graphite may be expected to have unusual behavior. We grow these films on a bed of commercially available graphite fibers that serve the dual function of a current collector. The electrochemical behavior of the composite is measured as a function of the thickness of the SiCO films. Thick films approach the typical behavior of bulk SiCO (which has three times the capacity of graphite, but suffers from poor first cycle efficiency). However, films, approximately 100 nm thick, show high first cycle efficiency as well as high capacity. The composite performs better than the prediction from the rule-of-mixtures, which further substantiates the unusual behavior of the thin-film architecture. The Raman spectra of these thin films also differ from bulk SiCO. The development of thin graphite fibers, with a high surface to volume ratio that have the same capacity as the current graphite-powder technology, coupled with manufacturing of these thin-films by a liquid-polymer precursor based process, can propel these results toward commercialization.

  17. Preparation of graphite oxide by sodium cholate intercalation and sonication from Indonesian natural graphite

    NASA Astrophysics Data System (ADS)

    Panatarani, Camellia; Maulana, Ayu Oktama; Rianto, Anton; Joni, I. Made

    2016-02-01

    Graphite oxide is widely use in renewable energy application such as solar cells, fuel-cells, battery electrodes, catalyst support, etc. This paper reports the preparation of graphite oxide from Indonesian natural graphite by sodium cholate intercalation. The enrichment process of as received graphite with carbon content of 60% was carried out by using acid leaching (HF) method. The enrichment process successfully obtained graphite with carbon content 95.61% with contaminant minerals observed by EDS were magnesium and aluminum. Purified graphite was then intercalated by sodium cholate at various concentration and sonication time. The XRD results shows that preparation with concentration of sodium cholate 2 Wt.% and sonication 10 hours formed a peak characteristic of graphite oxide at 2θ=15°. In addition, the successful oxidation process designated by the C/O ratio of 15.75 observed from EDS and supported by the present of functional C-H and C-O obtained from the FTIR observation. It is concluded that the graphite oxide successfully prepared by intercalation using sodium cholate and sonication.

  18. Laboratory for Characterization of Irradiated Graphite

    SciTech Connect

    Karen A. Moore

    2010-03-01

    The newly completed Idaho National Laboratory (INL) Carbon Characterization Laboratory (CCL) is located in Labs C19 and C20 of the Idaho National Laboratory Research Center (IRC). The CCL was established under the Next Generation Nuclear Plant (NGNP) Project to support graphite and ceramic composite research and development activities. The research is in support of the Advanced Graphite Creep (AGC) experiment — a major material irradiation experiment within the NGNP Graphite program. The CCL is designed to characterize and test low activated irradiated materials such as high purity graphite, carbon-carbon composites, and silicon-carbide composite materials. The laboratory is fully capable of characterizing material properties for both irradiated and nonirradiated materials.

  19. Laser nanoablation of graphite

    NASA Astrophysics Data System (ADS)

    Frolov, V. D.; Pivovarov, P. A.; Zavedeeev, E. V.; Komlenok, M. S.; Kononenko, V. V.; Konov, V. I.

    2014-01-01

    Experimental data on laser ablation of highly oriented pyrolitic graphite by nanosecond pulsed UV ( nm) and green ( nm) lasers are presented. It was found that below graphite vaporization threshold 1 J/cm, the nanoablation regime can be realized with material removal rates as low as 10 nm/pulse. The difference between physical (vaporization) and physical-chemical (heating + oxidation) ablation regimes is discussed. Special attention is paid to the influence of laser fluence and pulse number on ablation kinetics. Possibility of laser-induced graphite surface nanostructuring has been demonstrated. Combination of tightly focused laser beam and sharp tip of scanning probe microscope was applied to improve material nanoablation.

  20. Design of an electrolyte composition for stable and rapid charging-discharging of a graphite negative electrode in a bis(fluorosulfonyl)imide-based ionic liquid

    NASA Astrophysics Data System (ADS)

    Matsui, Yukiko; Yamagata, Masaki; Murakami, Satoshi; Saito, Yasuteru; Higashizaki, Tetsuya; Ishiko, Eriko; Kono, Michiyuki; Ishikawa, Masashi

    2015-04-01

    We evaluate the effects of lithium salt on the charge-discharge performance of a graphite negative electrode in 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMImFSI) ionic liquid-based electrolytes. Although the graphite negative electrode exhibits good cyclability and rate capability in both 0.43 mol dm-3 LiFSI/EMImFSI and LiTFSI/EMImFSI (TFSI- = bis(trifluoromethylsulfonyl)imide) at room temperature, only the LiFSI/EMImFSI system enables the graphite electrode to be operated with sufficient discharge capacity at the low temperature of 0 °C, even though there is no noticeable difference in ionic conductivity, compared with LiTFSI/EMImFSI. Furthermore, a clear difference in the low-temperature behaviors of the two cells composed of EMImFSI with a high-concentration of lithium salts is observed. Additionally, charge-discharge operation of the graphite electrode at C-rate of over 5.0 can be achieved using of the high-concentration LiFSI/EMImFSI electrolyte. Considering the low-temperature characteristics in both high-concentration electrolytes, the stable and rapid charge-discharge operation in the high-concentration LiFSI/EMImFSI is presumably attributed to a suitable electrode/electrolyte interface with low resistivity. These results suggest that optimization of the electrolyte composition can realize safe and high-performance lithium-ion batteries that utilize ionic liquid-based electrolytes.

  1. NEW METHOD OF GRAPHITE PREPARATION

    DOEpatents

    Stoddard, S.D.; Harper, W.T.

    1961-08-29

    BS>A method is described for producing graphite objects comprising mixing coal tar pitch, carbon black, and a material selected from the class comprising raw coke, calcined coke, and graphite flour. The mixture is placed in a graphite mold, pressurized to at least 1200 psi, and baked and graphitized by heating to about 2500 deg C while maintaining such pressure. (AEC)

  2. Status of ASME Section III Task Group on Graphite Support Core Structures

    SciTech Connect

    Robert L. Bratton; Tim D. Burchell

    2005-08-01

    This report outlines the roadmap that the ASME Project Team on Graphite Core Supports is pursuing to establish design codes for unirradiated and irradiated graphite core components during its first year of operation. It discusses the deficiencies in the proposed Section III, Division 2, Subsection CE graphite design code and the different approaches the Project Team has taken to address those deficiencies.

  3. Fission Product Sorptivity in Graphite

    SciTech Connect

    Tompson, Jr., Robert V.; Loyalka, Sudarshan; Ghosh, Tushar; Viswanath, Dabir; Walton, Kyle; Haffner, Robert

    2015-04-01

    graduate student meant that data acquisition with the packed bed systems ended up competing for the graduate student’s available time with the electrodynamic balance redesign and assembly portions of the project. This competition for available time was eventually mitigated to some extent by the later recruitment of an undergraduate student to help with data collection using the packed bed system. It was only the recruitment of the second student that allowed the single particle balance design and construction efforts to proceed as far as they did during the project period. It should be added that some significant time was also spent by the graduate student cataloging previous work involving graphite. This eventually resulted in a review paper being submitted and accepted (“Adsorption of Iodine on Graphite in High Temperature Gas-Cooled Reactor Systems: A Review,” Kyle L. Walton, Tushar K. Ghosh, Dabir S. Viswanath, Sudarshan K. Loyalka, Robert V. Tompson). Our specific revised objectives in this project were as follows: Experimentally obtain isotherms of Iodine for reactor grade IG-110 samples of graphite particles over a range of temperatures and pressures using an EDB and a temperature controlled EDB; Experimentally obtain isotherms of Iodine for reactor grade IG-110 samples of graphite particles over a range of temperatures and pressures using a packed column bed apparatus; Explore the effect that charge has on the adsorption isotherms of iodine by varying the charges on and the voltages used to suspend the microscopic particles in the EDB; and To interpret these results in terms of the existing models (Langmuir, BET, Freundlich, and others) which we will modify as necessary to include charge related effects.

  4. Role of Nuclear Grade Graphite in Oxidation in Modular HTGRs

    SciTech Connect

    Willaim Windes; G. Strydom; J. Kane; R. Smith

    2014-11-01

    The passively safe High Temperature Gas-cooled Reactor (HTGR) design is one of the primary concepts considered for Generation IV and Small Modular Reactor (SMR) programs. The helium cooled, nuclear grade graphite moderated core achieves extremely high operating temperatures allowing either industrial process heat or electricity generation at high efficiencies. In addition to their neutron moderating properties, nuclear grade graphite core components provide excellent high temperature stability, thermal conductivity, and chemical compatibility with the high temperature nuclear fuel form. Graphite has been continuously used in nuclear reactors since the 1940’s and has performed remarkably well over a wide range of core environments and operating conditions. Graphite moderated, gas-cooled reactor designs have been safely used for research and power production purposes in multiple countries since the inception of nuclear energy development. However, graphite is a carbonaceous material, and this has generated a persistent concern that the graphite components could actually burn during either normal or accident conditions [ , ]. The common assumption is that graphite, since it is ostensibly similar to charcoal and coal, will burn in a similar manner. While charcoal and coal may have the appearance of graphite, the internal microstructure and impurities within these carbonaceous materials are very different. Volatile species and trapped moisture provide a source of oxygen within coal and charcoal allowing them to burn. The fabrication process used to produce nuclear grade graphite eliminates these oxidation enhancing impurities, creating a dense, highly ordered form of carbon possessing high thermal diffusivity and strongly (covalently) bonded atoms.

  5. Graphite matrix materials for nuclear waste isolation

    SciTech Connect

    Morgan, W.C.

    1981-06-01

    At low temperatures, graphites are chemically inert to all but the strongest oxidizing agents. The raw materials from which artificial graphites are produced are plentiful and inexpensive. Morover, the physical properties of artificial graphites can be varied over a very wide range by the choice of raw materials and manufacturing processes. Manufacturing processes are reviewed herein, with primary emphasis on those processes which might be used to produce a graphite matrix for the waste forms. The approach, recommended herein, involves the low-temperature compaction of a finely ground powder produced from graphitized petroleum coke. The resultant compacts should have fairly good strength, low permeability to both liquids and gases, and anisotropic physical properties. In particular, the anisotropy of the thermal expansion coefficients and the thermal conductivity should be advantageous for this application. With two possible exceptions, the graphite matrix appears to be superior to the metal alloy matrices which have been recommended in prior studies. The two possible exceptions are the requirements on strength and permeability; both requirements will be strongly influenced by the containment design, including the choice of materials and the waste form, of the multibarrier package. Various methods for increasing the strength, and for decreasing the permeability of the matrix, are reviewed and discussed in the sections in Incorporation of Other Materials and Elimination of Porosity. However, it would be premature to recommend a particular process until the overall multi-barrier design is better defined. It is recommended that increased emphasis be placed on further development of the low-temperature compacted graphite matrix concept.

  6. Recompressed exfoliated graphite articles

    DOEpatents

    Zhamu, Aruna; Shi, Jinjun; Guo, Jiusheng; Jang, Bor Z

    2013-08-06

    This invention provides an electrically conductive, less anisotropic, recompressed exfoliated graphite article comprising a mixture of (a) expanded or exfoliated graphite flakes; and (b) particles of non-expandable graphite or carbon, wherein the non-expandable graphite or carbon particles are in the amount of between about 3% and about 70% by weight based on the total weight of the particles and the expanded graphite flakes combined; wherein the mixture is compressed to form the article having an apparent bulk density of from about 0.1 g/cm.sup.3 to about 2.0 g/cm.sup.3. The article exhibits a thickness-direction conductivity typically greater than 50 S/cm, more typically greater than 100 S/cm, and most typically greater than 200 S/cm. The article, when used in a thin foil or sheet form, can be a useful component in a sheet molding compound plate used as a fuel cell separator or flow field plate. The article may also be used as a current collector for a battery, supercapacitor, or any other electrochemical cell.

  7. Graphite Gamma Scan Results

    SciTech Connect

    Mark W. Drigert

    2014-04-01

    This report documents the measurement and data analysis of the radio isotopic content for a series of graphite specimens irradiated in the first Advanced Graphite Creep (AGC) experiment, AGC-1. This is the first of a series of six capsules planned as part of the AGC experiment to fully characterize the neutron irradiation effects and radiation creep behavior of current nuclear graphites. The AGC-1 capsule was irradiated in the Advanced Test Reactor (ATR) at INL at approximately 700 degrees C and to a peak dose of 7 dpa (displacements per atom). Details of the irradiation conditions and other characterization measurements performed on specimens in the AGC-1 capsule can be found in “AGC-1 Specimen Post Irradiation Data Report” ORNL/TM 2013/242. Two specimens from six different graphite types are analyzed here. Each specimen is 12.7 mm in diameter by 25.4 mm long. The isotope with the highest activity was 60Co. Graphite type NBG-18 had the highest content of 60Co with an activity of 142.89 µCi at a measurement distance of 47 cm.

  8. Interlayer interactions in graphites

    PubMed Central

    Chen, Xiaobin; Tian, Fuyang; Persson, Clas; Duan, Wenhui; Chen, Nan-xian

    2013-01-01

    Based on ab initio calculations of both the ABC- and AB-stacked graphites, interlayer potentials (i.e., graphene-graphene interaction) are obtained as a function of the interlayer spacing using a modified Möbius inversion method, and are used to calculate basic physical properties of graphite. Excellent consistency is observed between the calculated and experimental phonon dispersions of AB-stacked graphite, showing the validity of the interlayer potentials. More importantly, layer-related properties for nonideal structures (e.g., the exfoliation energy, cleave energy, stacking fault energy, surface energy, etc.) can be easily predicted from the interlayer potentials, which promise to be extremely efficient and helpful in studying van der Waals structures. PMID:24192753

  9. Cesium diffusion in graphite

    SciTech Connect

    Evans, R.B. III; Davis, W. Jr.; Sutton, A.L. Jr.

    1980-05-01

    Experiments on diffusion of /sup 137/Cs in five types of graphite were performed. The document provides a completion of the report that was started and includes a presentation of all of the diffusion data, previously unpublished. Except for data on mass transfer of /sup 137/Cs in the Hawker-Siddeley graphite, analyses of experimental results were initiated but not completed. The mass transfer process of cesium in HS-1-1 graphite at 600 to 1000/sup 0/C in a helium atmosphere is essentially pure diffusion wherein values of (E/epsilon) and ..delta..E of the equation D/epsilon = (D/epsilon)/sub 0/ exp (-..delta..E/RT) are about 4 x 10/sup -2/ cm/sup 2//s and 30 kcal/mole, respectively.

  10. Irradiation Creep in Graphite

    SciTech Connect

    Ubic, Rick; Butt, Darryl; Windes, William

    2014-03-13

    An understanding of the underlying mechanisms of irradiation creep in graphite material is required to correctly interpret experimental data, explain micromechanical modeling results, and predict whole-core behavior. This project will focus on experimental microscopic data to demonstrate the mechanism of irradiation creep. High-resolution transmission electron microscopy should be able to image both the dislocations in graphite and the irradiation-induced interstitial clusters that pin those dislocations. The team will first prepare and characterize nanoscale samples of virgin nuclear graphite in a transmission electron microscope. Additional samples will be irradiated to varying degrees at the Advanced Test Reactor (ATR) facility and similarly characterized. Researchers will record microstructures and crystal defects and suggest a mechanism for irradiation creep based on the results. In addition, the purchase of a tensile holder for a transmission electron microscope will allow, for the first time, in situ observation of creep behavior on the microstructure and crystallographic defects.

  11. Interlayer interactions in graphites

    NASA Astrophysics Data System (ADS)

    Chen, Xiaobin; Tian, Fuyang; Persson, Clas; Duan, Wenhui; Chen, Nan-Xian

    2013-11-01

    Based on ab initio calculations of both the ABC- and AB-stacked graphites, interlayer potentials (i.e., graphene-graphene interaction) are obtained as a function of the interlayer spacing using a modified Möbius inversion method, and are used to calculate basic physical properties of graphite. Excellent consistency is observed between the calculated and experimental phonon dispersions of AB-stacked graphite, showing the validity of the interlayer potentials. More importantly, layer-related properties for nonideal structures (e.g., the exfoliation energy, cleave energy, stacking fault energy, surface energy, etc.) can be easily predicted from the interlayer potentials, which promise to be extremely efficient and helpful in studying van der Waals structures.

  12. Coatings for graphite fibers

    NASA Technical Reports Server (NTRS)

    Galasso, F. S.; Scola, D. A.; Veltri, R. D.

    1980-01-01

    Graphite fibers released from composites during burning or an explosion caused shorting of electrical and electronic equipment. Silicon carbide, silica, silicon nitride and boron nitride were coated on graphite fibers to increase their electrical resistances. Resistances as high as three orders of magnitude higher than uncoated fiber were attained without any significant degradation of the substrate fiber. An organo-silicone approach to produce coated fibers with high electrical resistance was also used. Celion 6000 graphite fibers were coated with an organo-silicone compound, followed by hydrolysis and pyrolysis of the coating to a silica-like material. The shear and flexural strengths of composites made from high electrically resistant fibers were considerably lower than the shear and flexural strengths of composites made from the lower electrically resistant fibers. The lower shear strengths of the composites indicated that the coatings on these fibers were weaker than the coating on the fibers which were pyrolyzed at higher temperature.

  13. Transition from glass to graphite in manufacture of composite aircraft structure

    NASA Technical Reports Server (NTRS)

    Buffum, H. E.; Thompson, V. S.

    1978-01-01

    The transition from fiberglass reinforced plastic composites to graphite reinforced plastic composites is described. Structural fiberglass design and manufacturing background are summarized. How this experience provides a technology base for moving into graphite composite secondary structure and then to composite primary structure is considered. The technical requirements that must be fulfilled in the transition from glass to graphite composite structure are also included.

  14. Vibratory compaction tests on graphite powders for neutron shielding

    SciTech Connect

    Morgan, W.C.

    1982-05-01

    Mistures of three size ranges of graphite powders have been vibratory packed to densities as high as 1.40 gm/cm/sup 3/, which is 87.5 percent of the design density for the graphte segment of the FMIT test cell shield. Ultrasonic resonance vibration of the particles was determined to be an impractical method for achieving the required density. Possible options for fabricating the shield are: (1) revert to solid graphite, rather than vibratory packed powder, or (2) develop the mechanical vibratory compaction method, which would require (a) designing for the higher heat-load attendant with the reduced graphite density, or (b) increasing the thickness of the graphite segment by 15 percent or (c) seeking a new source of graphite powder with higher particle density.

  15. Improved graphite furnace atomizer

    DOEpatents

    Siemer, D.D.

    1983-05-18

    A graphite furnace atomizer for use in graphite furnace atomic absorption spectroscopy is described wherein the heating elements are affixed near the optical path and away from the point of sample deposition, so that when the sample is volatilized the spectroscopic temperature at the optical path is at least that of the volatilization temperature, whereby analyteconcomitant complex formation is advantageously reduced. The atomizer may be elongated along its axis to increase the distance between the optical path and the sample deposition point. Also, the atomizer may be elongated along the axis of the optical path, whereby its analytical sensitivity is greatly increased.

  16. Lightweight graphite/polyimide panels

    NASA Technical Reports Server (NTRS)

    Poesch, J. G.; Merlette, J. B.

    1973-01-01

    Panels are constructed of honeycombed polyimide/graphite core covered with thin face sheet of same material. Fabrication is based on extension of thin-gage graphite technology and modification of glass filament polyimide honeycomb techniques.

  17. Development of Graphite/Epoxy Corner Fittings

    NASA Technical Reports Server (NTRS)

    Faile, G.; Hollis, R.; Ledbetter, F.; Maldonado, J.; Sledd, J.; Stuckey, J.; Waggoner, G.; Engler, E.

    1986-01-01

    Report documents development project aimed at improving design and load-carrying ability of complicated corner fitting for optical bench. New fitting made of graphite filaments in epoxy-resin matrix. Composite material selected as replacement for titanium because lighter and dimensions change little with temperature variations.

  18. Scanning tunneling microscopy on graphite and gold

    NASA Astrophysics Data System (ADS)

    Guichar, G. M.; Han, B.; Morand, M.; Belkaid, M. S.

    1993-03-01

    A compact, UHV-compatible scanning tunneling microscope has been built together with the necessary controlling electronics. We report on the design, development and evaluation of this setup. Some experimental results performed on highly oriented pyrolitic graphite and gold evaporated on stainless steel samples are presented.

  19. Coatings for Graphite Fibers

    NASA Technical Reports Server (NTRS)

    Galasso, F. S.; Scola, D. A.; Veltri, R. D.

    1980-01-01

    Several approaches for applying high resistance coatings continuously to graphite yarn were investigated. Two of the most promising approaches involved (1) chemically vapor depositing (CVD) SiC coatings on the surface of the fiber followed by oxidation, and (2) drawing the graphite yarn through an organo-silicone solution followed by heat treatments. In both methods, coated fibers were obtained which exhibited increased electrical resistances over untreated fibers and which were not degraded. This work was conducted in a previous program. In this program, the continuous CVD SiC coating process used on HTS fiber was extended to the coating of HMS, Celion 6000, Celion 12000 and T-300 graphite fiber. Electrical resistances three order of magnitude greater than the uncoated fiber were measured with no significant degradation of the fiber strength. Graphite fibers coated with CVD Si3N4 and BN had resistances greater than 10(exp 6) ohm/cm. Lower pyrolysis temperatures were used in preparing the silica-like coatings also resulting in resistances as high as three orders of magnitude higher than the uncoated fiber. The epoxy matrix composites prepared using these coated fibers had low shear strengths indicating that the coatings were weak.

  20. Graphite criteria peer review

    SciTech Connect

    1986-09-01

    This report documents a review of the stress criteria proposed for the graphite components of the modular high temperature gas-cooled reactor (MHTGR) core. The review was conducted by a panel of six independent consultants, chosen for their expertise over a range of relevant disciplines.

  1. (Irradiation creep of graphite)

    SciTech Connect

    Kennedy, C.R.

    1990-12-21

    The traveler attended the Conference, International Symposium on Carbon, to present an invited paper, Irradiation Creep of Graphite,'' and chair one of the technical sessions. There were many papers of particular interest to ORNL and HTGR technology presented by the Japanese since they do not have a particular technology embargo and are quite open in describing their work and results. In particular, a paper describing the failure of Minor's law to predict the fatigue life of graphite was presented. Although the conference had an international flavor, it was dominated by the Japanese. This was primarily a result of geography; however, the work presented by the Japanese illustrated an internal program that is very comprehensive. This conference, a result of this program, was better than all other carbon conferences attended by the traveler. This conference emphasizes the need for US participation in international conferences in order to stay abreast of the rapidly expanding HTGR and graphite technology throughout the world. The United States is no longer a leader in some emerging technologies. The traveler was surprised by the Japanese position in their HTGR development. Their reactor is licensed and the major problem in their graphite program is how to eliminate it with the least perturbation now that most of the work has been done.

  2. GRAPHITE BONDING METHOD

    DOEpatents

    King, L.D.P.

    1964-02-25

    A process for bonding or joining graphite members together in which a thin platinum foil is placed between the members, heated in an inert atmosphere to a temperature of 1800 deg C, and then cooled to room temperature is described. (AEC)

  3. Structural graphitic carbon foams

    SciTech Connect

    Kearns, K.M.; Anderson, H.J.

    1998-12-31

    Graphitic carbon foams are a unique material form with very high structural and thermal properties at a light weight. A process has been developed to produce microcellular, open-celled graphitic foams. The process includes heating a mesophase pitch preform above the pitch melting temperature in a pressurized reactor. At the appropriate time, the pressure is released, the gas nucleates bubbles, and these bubbles grow forming the pitch into the foam structure. The resultant foamed pitch is then stabilized in an oxygen environment. At this point a rigid structure exists with some mechanical integrity. The foam is then carbonized to 800 C followed by a graphitization to 2700 C. The shear action from the growing bubbles aligns the graphitic planes along the foam struts to provide the ideal structure for good mechanical properties. Some of these properties have been characterized for some of the foam materials. It is known that variations of the blowing temperature, blowing pressure and saturation time result in foams of variously sized with mostly open pores; however, the mechanism of bubble nucleation is not known. Therefore foams were blown with various gases to begin to determine the nucleation method. These gases are comprised of a variety of molecular weights as well as a range of various solubility levels. By examining the resultant structures of the foam, differences were noted to develop an explanation of the foaming mechanism.

  4. Intercalating oleylamines in graphite oxide.

    PubMed

    Yang, Kaikun; Liang, Si; Zou, Lianfeng; Huang, Liwei; Park, Cheol; Zhu, Lisheng; Fang, Jiye; Fu, Qiang; Wang, Howard

    2012-02-01

    Graphite oxide has been synthesized from raw graphite particles and been treated with various mass amounts of oleylamine as intercalants to form intercalation compounds. X-ray diffraction patterns reveal that the inter-sheet distances strongly depend on the graphite oxide to oleylamine mass ratios. The equilibrium-like behavior implies diffusion-dominated oleylamine adsorption on graphite oxide in solution and excluded volume intercalations among oleylamine-adsorbed graphite oxide during restacking. The intercalation compounds are soluble in organic solvents, and their applications in the fabrication of transparent and conductive coatings have been demonstrated. PMID:22229856

  5. Development and fabrication of a graphite polyimide box beam

    NASA Technical Reports Server (NTRS)

    Nadler, M. A.; Darms, F. J.

    1972-01-01

    The state-of-the-art of graphite/polyimide structures was evaluated and key design and fabrication issues to be considered in future hardware programs are defined. The fabrication and testing at 500 F of a graphite/polyimide center wing box beam using OV-10A aircraft criteria was accomplished. The baseline design of this box was developed in a series of studies of other advanced composite materials: glass/epoxy, boron/epoxy, and boron/polyimide. The use of this basic design permits ready comparison of the performance of graphite/polyimide with these materials. Modifications to the baseline composite design were made only in those areas effected by the change of materials. Processing studies of graphite fiber polyimide resins systems resulted in the selection of a Modmor II/Gemon L material.

  6. Carbon Characterization Laboratory Readiness to Receive Irradiated Graphite Samples

    SciTech Connect

    Karen A. Moore

    2011-05-01

    The Carbon Characterization Laboratory (CCL) is located in Labs C19 and C20 of the Idaho National Laboratory Research Center. The CCL was established under the Next Generation Nuclear Plant Project to support graphite and ceramic composite research and development activities. The research conducted in this laboratory will support the Advanced Graphite Creep experiments—a major series of material irradiation experiments within the Next Generation Nuclear Plant Graphite program. The CCL is designed to characterize and test low activated irradiated materials such as high purity graphite, carbon-carbon composites, silicon-carbide composite, and ceramic materials. The laboratory is fully capable of characterizing material properties for both irradiated and nonirradiated materials. Major infrastructural modifications were undertaken to support this new radiological facility at Idaho National Laboratory. Facility modifications are complete, equipment has been installed, radiological controls and operating procedures have been established and work management documents have been created to place the CCL in readiness to receive irradiated graphite samples.

  7. A graphite-lined regeneratively cooled thrust chamber

    NASA Technical Reports Server (NTRS)

    Stubbs, V. R.

    1972-01-01

    Design concepts, based on use of graphite as a thermal barrier for regeneratively cooled FLOX-methane thrust chambers, have been screened and concepts selected for detailed thermodynamic, stress, and fabrication analyses. A single design employing AGCarb-101, a fibrous graphite composite material, for a thermal barrier liner and an electroformed nickel structure with integral coolant passages was selected for fabrication and testing. The fabrication processes and the test results are described and illustrated.

  8. Effects of prestresses on mechanical properties of isotropic graphite materials

    NASA Astrophysics Data System (ADS)

    Oku, T.; Kurumada, A.; Imamura, Y.; Kawamata, K.; Shiraishi, M.

    1998-10-01

    Graphite materials which are used for plasma facing components and other components are subjected to stresses due to the high heat flux from the fusion plasma. Some mechanical properties of graphite materials can change due to the prestresses. The property changes should be considered for the design of the plasma facing components. The purpose of this study is to examine the effects of prestresses on the mechanical properties of isotropic graphite materials. Compressive prestresses were applied to two kinds of isotropic fine-grained graphites (IG-430 and IG-11) at 298 K (both), 1873 K (IG-11), 2273 K (IG-11) and 2283 K (IG-430). As a result, the decrease in Young's modulus for IG-430 due to high-temperature prestressing was 56% which was much larger than the 6.4% that was due to prestressing at 298 K. The results for IG-11 were the same as those for IG-430 graphite. This finding was considered to be due primarily to a difference in degree of the preferred orientation of crystallites in the graphite on the basis of the Bacon anisotropy factor (BAF) obtained from X-ray diffraction measurement of the prestressed specimens. Furthermore, high-temperature compressive prestressing produced an increase in the strength of the isotropic graphite, although room temperature prestressing produced no such effect. The results obtained here suggest that the isotropic graphite which is subjected to high-temperature compressive stresses can become anisotropic in service.

  9. Graphite Polyhedral Crystals

    NASA Astrophysics Data System (ADS)

    Gogotsi, Yury; Libera, Joseph A.; Kalashnikov, Nikolay; Yoshimura, Masahiro

    2000-10-01

    Polyhedral nano- and microstructures with shapes of faceted needles, rods, rings, barrels, and double-tipped pyramids, which we call graphite polyhedral crystals (GPCs), have been discovered. They were found in pores of glassy carbon. They have nanotube cores and graphite faces, and they can exhibit unusual sevenfold, ninefold, or more complex axial symmetry. Although some are giant radially extended nanotubes, Raman spectroscopy and transmission electron microscopy suggest GPCs have a degree of perfection higher than in multiwall nanotubes of similar size. The crystals are up to 1 micrometer in cross section and 5 micrometers in length, and they can probably be grown in much larger sizes. Preliminary results suggest a high electrical conductivity, strength, and chemical stability of GPC.

  10. Industrial Applications of Graphite Fluoride Fibers

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh; Kucera, Donald

    1991-01-01

    Based on fluorination technology developed during 1934 to 1959, and the fiber technology developed during the 1970s, a new process was developed to produce graphite fluoride fibers. In the process, pitch based graphitized carbon fibers are at first intercalated and deintercalated several times by bromine and iodine, followed by several cycles of nitrogen heating and fluorination at 350 to 370 C. Electrical, mechanical, and thermal properties of this fiber depend on the fluorination process and the fluorine content of the graphite fluoride product. However, these properties are between those of graphite and those of PTFE (Teflon). Therefore, it is considered to be a semiplastic. The physical properties suggest that this new material may have many new and unexplored applications. For example, it can be a thermally conductive electrical insulator. Its coefficient of thermal expansion (CTE) can be adjusted to match that of silicon, and therefore, it can be a heat sinking printed circuit board which is CTE compatible with silicon. Using these fibers in printed circuit boards may provide improved electrical performance and reliability of the electronics on the board over existing designs. Also, since it releases fluorine at 300 C or higher, it can be used as a material to store fluorine and to conduct fluorination. This application may simplify the fluorination process and reduce the risk of handling fluorine.

  11. CMB-13 research on carbon and graphite

    NASA Technical Reports Server (NTRS)

    Smith, M. C.

    1972-01-01

    Preliminary results of the research on carbon and graphite accomplished during this report period are presented. Included are: particle characteristics of Santa Maria fillers, compositions and density data for hot-molded Santa Maria graphites, properties of hot-molded Santa Maria graphites, and properties of hot-molded anisotropic graphites. Ablation-resistant graphites are also discussed.

  12. METHOD OF FABRICATING A GRAPHITE MODERATED REACTOR

    DOEpatents

    Kratz, H.R.

    1963-05-01

    S>A nuclear reactor formed of spaced bodies of uranium and graphite blocks is improved by diffusing helium through the graphite blocks in order to replace the air in the pores of the graphite with helium. The helium-impregnated graphite conducts heat better, and absorbs neutrons less, than the original air- impregnated graphite. (AEC)

  13. Heat exchanger using graphite foam

    SciTech Connect

    Campagna, Michael Joseph; Callas, James John

    2012-09-25

    A heat exchanger is disclosed. The heat exchanger may have an inlet configured to receive a first fluid and an outlet configured to discharge the first fluid. The heat exchanger may further have at least one passageway configured to conduct the first fluid from the inlet to the outlet. The at least one passageway may be composed of a graphite foam and a layer of graphite material on the exterior of the graphite foam. The layer of graphite material may form at least a partial barrier between the first fluid and a second fluid external to the at least one passageway.

  14. Graphitic packing removal tool

    SciTech Connect

    Meyers, K.E.; Kolsun, G.J.

    1996-12-31

    Graphitic packing removal tools are described for removal of the seal rings in one piece from valves and pumps. The packing removal tool has a cylindrical base ring the same size as the packing ring with a surface finish, perforations, knurling or threads for adhesion to the seal ring. Elongated leg shanks are mounted axially along the circumferential center. A slit or slits permit insertion around shafts. A removal tool follower stabilizes the upper portion of the legs to allow a spanner wrench to be used for insertion and removal.

  15. Graphitic packing removal tool

    DOEpatents

    Meyers, K.E.; Kolsun, G.J.

    1997-11-11

    Graphitic packing removal tools for removal of the seal rings in one piece are disclosed. The packing removal tool has a cylindrical base ring the same size as the packing ring with a surface finish, perforations, knurling or threads for adhesion to the seal ring. Elongated leg shanks are mounted axially along the circumferential center. A slit or slits permit insertion around shafts. A removal tool follower stabilizes the upper portion of the legs to allow a spanner wrench to be used for insertion and removal. 5 figs.

  16. Graphitic packing removal tool

    DOEpatents

    Meyers, Kurt Edward; Kolsun, George J.

    1997-01-01

    Graphitic packing removal tools for removal of the seal rings in one piece. he packing removal tool has a cylindrical base ring the same size as the packing ring with a surface finish, perforations, knurling or threads for adhesion to the seal ring. Elongated leg shanks are mounted axially along the circumferential center. A slit or slits permit insertion around shafts. A removal tool follower stabilizes the upper portion of the legs to allow a spanner wrench to be used for insertion and removal.

  17. Purification and preparation of graphite oxide from natural graphite

    NASA Astrophysics Data System (ADS)

    Panatarani, C.; Muthahhari, N.; Rianto, Anton; Joni, I. Made

    2016-03-01

    Graphite oxide has attracted much interest as a possible route for preparation of natural graphite in the large-scale production and manipulation of graphene as a material with extraordinary electronic properties. Graphite oxide was prepared by modified Hummers method from purified natural graphite sample from West Kalimantan. We demonstrated that natural graphite is well-purified by acid leaching method. The purified graphite was proceed for intercalating process by modifying Hummers method. The modification is on the reaction time and temperature of the intercalation process. The materials used in the intercalating process are H2SO4 and KMNO4. The purified natural graphite is analyzed by carbon content based on Loss on Ignition test. The thermo gravimetricanalysis and the Fouriertransform infrared spectroscopy are performed to investigate the oxidation results of the obtained GO which is indicated by the existence of functional groups. In addition, the X-ray diffraction and energy dispersive X-ray spectroscopy are also applied to characterize respectively for the crystal structure and elemental analysis. The results confirmed that natural graphite samples with 68% carbon content was purified into 97.68 % carbon content. While the intercalation process formed a formation of functional groups in the obtained GO. The results show that the temperature and reaction times have improved the efficiency of the oxidation process. It is concluded that these method could be considered as an important route for large-scale production of graphene.

  18. Atomic resolution images of graphite in air

    SciTech Connect

    Grigg, D.A.; Shedd, G.M.; Griffis, D.; Russell, P.E.

    1988-12-01

    One sample used for proof of operation for atomic resolution in STM is highly oriented pyrolytic graphite (HOPG). This sample has been imaged with many different STM`s obtaining similar results. Atomic resolution images of HOPG have now been obtained using an STM designed and built at the Precision Engineering Center. This paper discusses the theoretical predictions and experimental results obtained in imaging of HOPG.

  19. Graphite Oxidation Simulation in HTR Accident Conditions

    SciTech Connect

    El-Genk, Mohamed

    2012-10-19

    Massive air and water ingress, following a pipe break or leak in steam-generator tubes, is a design-basis accident for high-temperature reactors (HTRs). Analysis of these accidents in both prismatic and pebble bed HTRs requires state-of-the-art capability for predictions of: 1) oxidation kinetics, 2) air helium gas mixture stratification and diffusion into the core following the depressurization, 3) transport of multi-species gas mixture, and 4) graphite corrosion. This project will develop a multi-dimensional, comprehensive oxidation kinetics model of graphite in HTRs, with diverse capabilities for handling different flow regimes. The chemical kinetics/multi-species transport model for graphite burning and oxidation will account for temperature-related changes in the properties of graphite, oxidants (O2, H2O, CO), reaction products (CO, CO2, H2, CH4) and other gases in the mixture (He and N2). The model will treat the oxidation and corrosion of graphite in geometries representative of HTR core component at temperatures of 900°C or higher. The developed chemical reaction kinetics model will be user-friendly for coupling to full core analysis codes such as MELCOR and RELAP, as well as computational fluid dynamics (CFD) codes such as CD-adapco. The research team will solve governing equations for the multi-dimensional flow and the chemical reactions and kinetics using Simulink, an extension of the MATLAB solver, and will validate and benchmark the model's predictions using reported experimental data. Researchers will develop an interface to couple the validated model to a commercially available CFD fluid flow and thermal-hydraulic model of the reactor , and will perform a simulation of a pipe break in a prismatic core HTR, with the potential for future application to a pebble-bed type HTR.

  20. Design optimization of LiNi0.6Co0.2Mn0.2O2/graphite lithium-ion cells based on simulation and experimental data

    NASA Astrophysics Data System (ADS)

    Appiah, Williams Agyei; Park, Joonam; Song, Seonghyun; Byun, Seoungwoo; Ryou, Myung-Hyun; Lee, Yong Min

    2016-07-01

    LiNi0.6Co0.2Mn0.2O2 cathodes of different thicknesses and porosities are prepared and tested, in order to optimize the design of lithium-ion cells. A mathematical model for simulating multiple types of particles with different contact resistances in a single electrode is adopted to study the effects of the different cathode thicknesses and porosities on lithium-ion transport using the nonlinear least squares technique. The model is used to optimize the design of LiNi0.6Co0.2Mn0.2O2/graphite lithium-ion cells by employing it to generate a number of Ragone plots. The cells are optimized for cathode porosity and thickness, while the anode porosity, anode-to-cathode capacity ratio, thickness and porosity of separator, and electrolyte salt concentration are held constant. Optimization is performed for discharge times ranging from 10 h to 5 min. Using the Levenberg-Marquardt method as a fitting technique, accounting for multiple particles with different contact resistances, and employing a rate-dependent solid-phase diffusion coefficient results in there being good agreement between the simulated and experimentally determined discharge curves. The optimized parameters obtained from this study should serve as a guide for the battery industry as well as for researchers for determining the optimal cell design for different applications.

  1. Examining graphite reinforcement in composites

    NASA Technical Reports Server (NTRS)

    Sanders, R. E.; Yates, C. I.

    1980-01-01

    Structure of graphite layers in composite parts can be checked by pyrolizing epoxy portion of composite samples. After 2-3 hours in nitrogen atmosphere at 540 C, only graphite fibers remain. These can be separated and checked for proper number, thickness, and orientation.

  2. REFRACTORY COATING FOR GRAPHITE MOLDS

    DOEpatents

    Stoddard, S.D.

    1958-06-24

    Refractory coating for graphite molds used in the casting of uranium is described. The coating is an alumino-silicate refractory composition which may be used as a mold surface in solid form or as a coating applied to the graphite mold. The composition consists of a mixture of ball clay, kaolin, alumina cement, alumina, water, sodium silicate, and sodium carbonate.

  3. Cryotribology of diamond and graphite

    SciTech Connect

    Iwasa, Yukikazu; Ashaboglu, A.F.; Rabinowicz, E.R.

    1996-12-31

    An experimental study was carried out on the tribological behavior of materials of interest in cryogenic applications, focusing on diamond and graphite. Both natural diamond (referred in the text as diamond) and chemical-vapor-deposition (CVD) diamond (CVD-diamond) were used. The experiment was carried out using a pin-on-disk tribometer capable of operating at cryogenic temperatures, from 4.2 to 293 K. Two basic scenarios of testing were used: (1) frictional coefficient ({mu}) vs velocity (v) characteristics at constant temperatures; (2) {mu} vs temperature (T) behavior at fixed sliding speeds. For diamond/CVD-diamond, graphite/CVD-diamond, stainless steel/CVD-diamond pairs, {mu}`s are virtually velocity independent. For each of diamond/graphite, alumina/graphite, and graphite/graphite pairs, the {partial_derivative}{mu}/{partial_derivative}v characteristic is favorable, i.e., positive. For diamond/CVD-diamond and graphite/CVD-diamond pairs, {mu}`s are nearly temperature independent between in the range 77 - 293 K. Each {mu} vs T plot for pin materials sliding on graphite disks has a peak at a temperature in the range 100 - 200 K.

  4. Graphite fluoride fibers and their applications in the space industry

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Chen; Long, Martin; Dever, Therese

    1990-01-01

    Characterization and potential space applications of graphite fluoride fibers from commercially available graphitized carbon fibers are presented. Graphite fluoride fibers with fluorine to carbon ratios of 0.65 and 0.68 were found to have electrical resistivity values of 10(exp 4) and 10(exp 11) Ohms-cm, respectively, and thermal conductivity values of 24 and 5 W/m-K, respectively. At this fluorine content range, the fibers have tensile strength of 0.25 + or - 0.10 GPa (36 + or - 14 ksi), Young's modulus of 170 + or - 30 GPa (25 + or - 5 Msi). The coefficient of thermal expansion value of a sample with fluorine to carbon ratio of 0.61 was found to be 7 ppm/C. These properties change and approach the graphite value as the fluorine content approach 0. Electrically insulative graphite fluoride fiber is at least five times more thermally conductive than fiberglass. Therefore, it can be used as a heat sinking printed circuit board material for low temperature, long life power electronics in spacecraft. Also, partially fluorinated fiber with tailor-made physical properties to meet the requirements of certain engineering design can be produced. For example, a partially fluorinated fiber could have a predetermined CTE value in -1.5 to 7 ppm/C range and would be suitable for use in solar concentrators in solar dynamic power systems. It could also have a predetermined electrical resistivity value suitable for use as a low observable material. Experimental data indicate that slightly fluorinated graphite fibers are more durable in the atomic oxygen environment than pristine graphite. Therefore, fluorination of graphite used in the construction of spacecraft that would be exposed to the low Earth orbit atomic oxygen may protect defect sites in atomic oxygen protective coatings and therefore decrease the rate of degradation of graphite.

  5. Electronic structure of graphite oxide

    NASA Astrophysics Data System (ADS)

    Jeong, Hae Kyung; Yang, Cheolsoo; Kim, Bong Soo; Kim, Ki-Jeong

    2011-03-01

    We have investigated the electronic structure of graphite oxide by photoelectron spectroscopy at the Pohang Accelerator Laboratory, Korea. The typical sp 2 hybridization states found in graphite were also seen in graphite oxide. However, the π state disappeared near the Fermi level because of bonding between the π and oxygen-related states originating from graphite oxide, indicating electron transfer from graphite to oxygen and resulting in a downward shift of the highest occupied molecular orbital (HOMO) state to higher binding energies. The band gap opening increased to about 1.8 eV, and additional oxygen-related peaks were observed at 8.5 and 27 eV. This research was supported by the Basic Science Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Education, Science and Technology (2010-0004592), and partly by the MEST (2009-0087138). Experiments at the PLS were supported in part by POSTECH and MEST.

  6. PMR Graphite Engine Duct Development

    NASA Technical Reports Server (NTRS)

    Stotler, C. L.; Yokel, S. A.

    1989-01-01

    The objective was to demonstrate the cost and weight advantages that could be obtained by utilizing the graphite/PMR15 material system to replace titanium in selected turbofan engine applications. The first component to be selected as a basis for evaluation was the outer bypass duct of the General Electric F404 engine. The operating environment of this duct was defined and then an extensive mechanical and physical property test program was conducted using material made by processing techniques which were also established by this program. Based on these properties, design concepts to fabricate a composite version of the duct were established and two complete ducts fabricated. One of these ducts was proof pressure tested and then run successfully on a factory test engine for over 1900 hours. The second duct was static tested to 210 percent design limit load without failure. An improved design was then developed which utilized integral composite end flanges. A complete duct was fabricated and successfully proof pressure tested. The net results of this effort showed that a composite version of the outer duct would be 14 percent lighter and 30 percent less expensive that the titanium duct. The other type of structure chosen for investigation was the F404 fan stator assembly, including the fan stator vanes. It was concluded that it was feasible to utilize composite materials for this type structure but that the requirements imposed by replacing an existing metal design resulted in an inefficient composite design. It was concluded that if composites were to be effectively used in this type structure, the design must be tailored for composite application from the outset.

  7. Review of thermal properties of graphite composite materials

    SciTech Connect

    Kourtides, D.A.

    1987-12-01

    Flammability, thermal, and selected mechanical properties of composites fabricated with epoxy and other thermally stable resin matrices are described. Properties which were measured included limiting-oxygen index, smoke evolution, thermal degradation products, total-heat release, heat-release rates, mass loss, flame spread, ignition resistance, thermogravimetric analysis, and selected mechanical properties. The properties of 8 different graphite composite panels fabricated using four different resin matrices and two types of graphite reinforcement are described. The resin matrices included: XU71775/H795, a blend of vinyl polystyryl pyridine and bismaleimide; H795, a bismaleimide; Cycom 6162, a phenolic; and PSP 6022M, a polystyryl pyridine. The graphite fiber used was AS-4 in the form of either tape or fabric. The properties of these composites were compared with epoxy composites. It was determined that the blend of vinyl polystyryl pyridine and bismaleimide (XU71775/H795) with the graphite tape was the optimum design giving the lowest heat release rate.

  8. Review of thermal properties of graphite composite materials

    NASA Technical Reports Server (NTRS)

    Kourtides, D. A.

    1987-01-01

    Flammability, thermal, and selected mechanical properties of composites fabricated with epoxy and other thermally stable resin matrices are described. Properties which were measured included limiting-oxygen index, smoke evolution, thermal degradation products, total-heat release, heat-release rates, mass loss, flame spread, ignition resistance, thermogravimetric analysis, and selected mechanical properties. The properties of 8 different graphite composite panels fabricated using four different resin matrices and two types of graphite reinforcement are described. The resin matrices included: XU71775/H795, a blend of vinyl polystyryl pyridine and bismaleimide; H795, a bismaleimide; Cycom 6162, a phenolic; and PSP 6022M, a polystyryl pyridine. The graphite fiber used was AS-4 in the form of either tape or fabric. The properties of these composites were compared with epoxy composites. It was determined that the blend of vinyl polystyryl pyridine and bismaleimide (XU71775/H795) with the graphite tape was the optimum design giving the lowest heat release rate.

  9. Graphitic heat shields for solar probe missions

    NASA Technical Reports Server (NTRS)

    Lundell, J. H.

    1981-01-01

    The feasibility of using a graphitic heat-shield system on a solar probe going to within 4 solar radii of the center of the sun is investigated. An analysis of graphite vaporization, with commonly used vaporization coefficients, indicates that the maximum mass-loss rate from a conical shield as large as 4 m in diameter can be kept low enough to avoid interference with measurements of the solar environment. In addition to the mass-loss problem, the problem of protecting the payload from the high-temperature (up to 2300 K) primary shield must be solved. An analysis of radiation exchange between concentric disks provides a technique for designing the intermediate shielding. The technique is applied to the design of a system for the Starprobe spacecraft, and it is found that a system with 10 shields and a payload surface temperature of 600 K will have a payload diameter of 2.45 m. Since this is 61% of the 4-m diameter of the primary shield, it is concluded that a graphitic heat-shield system is feasible for the Starprobe mission.

  10. Hypervelocity impacts into graphite

    NASA Astrophysics Data System (ADS)

    Latunde-Dada, S.; Cheesman, C.; Day, D.; Harrison, W.; Price, S.

    2011-03-01

    Studies have been conducted into the characterisation of the behaviour of commercial graphite (brittle) when subjected to hypervelocity impacts by a range of projectiles. The experiments were conducted with a two-stage gas gun capable of launching projectiles of differing density and strength to speeds of about 6kms-1 at right angles into target plates. The damage caused is quantified by measurements of the crater depth and diameters. From the experimental data collected, scaling laws were derived which correlate the crater dimensions to the velocity and the density of the projectile. It was found that for moderate projectile densities the crater dimensions obey the '2/3 power law' which applies to ductile materials.

  11. Optical properties of graphite oxide and reduced graphite oxide

    NASA Astrophysics Data System (ADS)

    Jung, Eilho; Lee, Seokbae; Roh, Seulki; Hwang, Eunhee; Lee, Junghyun; Lee, Hyoyoung; Hwang, Jungseek

    2014-07-01

    We studied the optical properties of a graphite oxide and a reduced graphite oxide by using the optical spectroscopic technique. The graphite oxide does not show a finite dc conductivity and has several characteristic absorption modes in the mid-infrared region, caused by an epoxide functional group and hydroxyl and carboxyl moieties in the mid-infrared range. The reduced graphite oxide shows a Drude-like response in the far-infrared region and the estimated dc conductivity and electric mobility are around 200 Ω-1cm-1 and ˜100 cm2V-1s-1, respectively. We found that the optical conductivity cannot be fitted with a simple Drude model, which indicates that the charge carriers are correlated. We applied an extended Drude model and obtained the optical scattering rate and the optical effective mass. We found that the optical effective mass can carry information of both the enhanced mass by correlation and the electronic band structure.

  12. Graphitized needle cokes and natural graphites for lithium intercalation

    SciTech Connect

    Tran, T.D.; Spellman, L.M.; Pekala, R.W.; Goldberger, W.M.; Kinoshita, K.

    1996-05-10

    This paper examined effects of heat treatment and milling (before or after heat treatment) on the (electrochemical) intercalating ability of needle petroleum coke; natural graphite particles are included for comparison. 1 tab, 4 figs, 7 refs.

  13. Spent graphite fuel element processing

    SciTech Connect

    Holder, N.D.; Olsen, C.W.

    1981-07-01

    The Department of Energy currently sponsors two programs to demonstrate the processing of spent graphite fuel elements. General Atomic in San Diego operates a cold pilot plant to demonstrate the processing of both US and German high-temperature reactor fuel. Exxon Nuclear Idaho Company is demonstrating the processing of spent graphite fuel elements from Rover reactors operated for the Nuclear Rocket Propulsion Program. This work is done at Idaho National Engineering Laboratory, where a hot facility is being constructed to complete processing of the Rover fuel. This paper focuses on the graphite combustion process common to both programs.

  14. Graphite Isotope Ratio Method Development Report: Irradiation Test Demonstration of Uranium as a Low Fluence Indicator

    SciTech Connect

    Reid, B.D.; Gerlach, D.C.; Love, E.F.; McNeece, J.P.; Livingston, J.V.; Greenwood, L.R.; Petersen, S.L.; Morgan, W.C.

    1999-10-20

    This report describes an irradiation test designed to investigate the suitability of uranium as a graphite isotope ratio method (GIRM) low fluence indicator. GIRM is a demonstrated concept that gives a graphite-moderated reactor's lifetime production based on measuring changes in the isotopic ratio of elements known to exist in trace quantities within reactor-grade graphite. Appendix I of this report provides a tutorial on the GIRM concept.

  15. Mineral resource of the month: graphite

    USGS Publications Warehouse

    U.S. Geological Survey

    2008-01-01

    The article presents facts about graphite ideal for industrial applications. Among the characteristics of graphite are its metallic luster, softness, perfect basal cleavage and electrical conductivity. Batteries, brake linings and powdered metals are some of the products that make use of graphite. It attributes the potential applications for graphite in high-technology fields to innovations in thermal technology and acid-leaching techniques.

  16. Method of Obtaining Uniform Coatings on Graphite

    DOEpatents

    Campbell, I. E.

    1961-04-01

    A method is given for obtaining uniform carbide coatings on graphite bodies. According to the invention a metallic halide in vapor form is passed over the graphite body under such conditions of temperature and pressure that the halide reacts with the graphite to form a coating of the metal carbide on the surface of the graphite.

  17. METHOD OF OBTAINING UNIFORM COATINGS ON GRAPHITE

    DOEpatents

    Campbell, I.E.

    1961-04-01

    A method is given for obtaining uniform carbide coatings on graphite bodies. According to the invention a metallic halide in vapor form is passed over the graphite body under such conditions of temperature and pressure that the halide reacts with the graphite to form a coating of the metal carbide on the surface of the graphite.

  18. Fillers for improved graphite fiber retention by polymer matrix composites

    NASA Technical Reports Server (NTRS)

    House, E. E.; Sheppard, C. H.

    1981-01-01

    The results of a program designed to determine the extent to which elemental boron and boron containing fillers added to the matrix resin of graphite/epoxy composites prevent the release of graphite fibers when the composites are exposed to fire and impact conditions are described. The fillers evaluated were boron, boron carbide and aluminum boride. The conditions evaluated were laboratory simulations of those that could exist in the event of an aircraft crash and burn situation. The baseline (i.e., unfilled) laminates evaluated were prepared from commercially available graphite/epoxy. The baseline and filled laminates' mechanical properties, before and after isothermal and humidity aging, also were compared. It was found that a small amount of graphite fiber was released from the baseline graphite/epoxy laminates during the burn and impact conditions used in this program. However, the extent to which the fibers were released is not considered a severe enough problem to preclude the use of graphite reinforced composites in civil aircraft structure. It also was found that the addition of boron and boron containing fillers to the resin matrix eliminated this fiber release. Mechanical properties of laminates containing the boron and boron containing fillers were lower than those of the baseline laminates. These property degradations for two systems: boron (5 micron) at 2.5 percent filler loading, and boron (5 micron) at 5.0 percent filler loading do not appear severe enough to preclude their use in structural composite applications.

  19. Intercalated hybrid graphite fiber composite

    NASA Technical Reports Server (NTRS)

    Gaier, James R. (Inventor)

    1993-01-01

    The invention is directed to a highly conductive lightweight hybrid material and methods of producing the same. The hybrid composite is obtained by weaving strands of a high strength carbon or graphite fiber into a fabric-like structure, depositing a layer of carbon onto the structure, heat treating the structure to graphitize the carbon layer, and intercalating the graphitic carbon layer structure. A laminate composite material useful for protection against lightning strikes comprises at least one layer of the hybrid material over at least one layer of high strength carbon or graphite fibers. The composite material of the present invention is compatible with matrix compounds, has a coefficient of thermal expansion which is the same as underlying fiber layers, and is resistant to galvanic corrosion in addition to being highly conductive. These materials are useful in the aerospace industry, in particular as lightning strike protection for airplanes.

  20. CALANDRIA TYPE SODIUM GRAPHITE REACTOR

    DOEpatents

    Peterson, R.M.; Mahlmeister, J.E.; Vaughn, N.E.; Sanders, W.J.; Williams, A.C.

    1964-02-11

    A sodium graphite power reactor in which the unclad graphite moderator and fuel elements are contained within a core tank is described. The core tank is submersed in sodium within the reactor vessel. Extending longitudinally through the core thnk are process tubes with fuel elements positioned therein. A bellows sealing means allows axial expansion and construction of the tubes. Within the core tank, a leakage plenum is located below the graphite, and above the graphite is a gas space. A vent line regulates the gas pressure in the space, and another line removes sodium from the plenum. The sodium coolant flows from the lower reactor vessel through the annular space between the fuel elements and process tubes and out into the reactor vessel space above the core tank. From there, the heated coolant is drawn off through an outlet line and sent to the heat exchange. (AEC)

  1. A novel nanoporous graphitic composite.

    PubMed

    Wang, Zheng-Ming; Hoshinoo, Kumiko; Xue, M; Kanoh, Hirofumi; Ooi, Kenta

    2002-08-21

    A novel nanoporous composite containing micrographitic carbon layers is synthesized by preliminarily expanding the interlayer of an oxidized product of graphite using surfactant, followed by Si bridging/pillaring, and carbonization. PMID:12211211

  2. Graphite for the nuclear industry

    SciTech Connect

    Burchell, T.D.; Fuller, E.L.; Romanoski, G.R.; Strizak, J.P.

    1991-01-01

    Graphite finds applications in both fission and fusion reactors. Fission reactors harness the energy liberated when heavy elements, such as uranium or plutonium, fragment or fission''. Reactors of this type have existed for nearly 50 years. The first nuclear fission reactor, Chicago Pile No. 1, was constructed of graphite under a football stand at Stagg Field, University of Chicago. Fusion energy devices will produce power by utilizing the energy produced when isotopes of the element hydrogen are fused together to form helium, the same reaction that powers our sun. The role of graphite is very different in these two reactor systems. Here we summarize the function of the graphite in fission and fusion reactors, detailing the reasons for their selection and discussing some of the challenges associated with their application in nuclear fission and fusion reactors. 10 refs., 15 figs., 1 tab.

  3. Graphite-reinforced bone cement

    NASA Technical Reports Server (NTRS)

    Knoell, A. C.

    1976-01-01

    Chopped graphite fibers added to surgical bone cement form bonding agent with mechanical properties closely matched to those of bone. Curing reaction produces less heat, resulting in reduced traumatization of body tissues. Stiffness is increased without affecting flexural strength.

  4. Irradiation Induced Creep of Graphite

    SciTech Connect

    Burchell, Timothy D; Murty, Prof K.L.; Eapen, Dr. Jacob

    2010-01-01

    The current status of graphite irradiation induced creep strain prediction is reviewed and the major creep models are described. The ability of the models to quantitatively predict the irradiation induced creep strain of graphite is reported. Potential mechanisms of in-crystal creep are reviewed as are mechanisms of pore generation under stress. The case for further experimental work is made and the need for improved creep models across multi-scales is highlighted.

  5. Electronic applications of flexible graphite

    NASA Astrophysics Data System (ADS)

    Luo, Xiangcheng; Chugh, Randy; Biller, Brian C.; Hoi, Yie Meng; Chung, D. D. L.

    2002-05-01

    Flexible graphite is effective for electronic applications, specifically electromagnetic interference (EMI) gasketing, resistive heating, thermoelectric-energy generation, and heat dissipation. It is comparable to or better than conductive-filled silicone materials for EMI gasketing. The shielding effectiveness reaches 125 dB. Flexible graphite as a heating element provides temperatures up to 980°C, response half-time down to 4 sec, and heat output at 60 sec up to 5600 J. The through-thickness, absolute thermoelectric power of flexible graphite is -2.6 µV/°C. Flexible graphite is effective as a thermal-interface material if the thickness is low (0.13 mm), the density is low (1.1 g/cm3), and the contact pressure is high (11.1 MPa). These applications make use of the flexibility and compliance of flexible graphite, in addition to its electronic and thermal behavior. Compliance is particularly important for the use of flexible graphite as interface materials, whether the interface is electrom agnetic, thermoelectric, or thermal.

  6. Development of lead-free copper alloy-graphite casting. Annual report, January--December 1994

    SciTech Connect

    Rohatgi, P.K.

    1996-02-01

    Water model experiments were conducted to develop a two-stage stirring method for obtaining higher yields and a more uniform distribution of particles in copper alloys. This was followed by several melts for synthesis of copper-graphite alloys in which T1 was used as a wetting agent to improve the wettability of graphite in the copper melt. In the first stage, a vortex method was employed to facilitate the suction of graphite particles into the copper melt. In the second stage, the specially designed stirrer was used to avoid the formation of vortex in melt. The two stage stirring was found to considerably improve the recovery of graphite, over those obtained with the prior practice of single stage stirring. In addition, graphite recoveries increased with increasing Ti content. Flotation, fluidity, and directional solidification experiments were also conducted on copper-graphite alloys synthesized in this study. Tests showed that the spiral fluidity length of the yellow brass alloy increased with temperature and decreased with graphite. The fluidity of copper-graphite alloys investigated to date remained adequate to make a variety of castings. The observations of microstructure of directional solidification and flotation showed that in certain castings the graphite particles were agglomerated and they float to the upper part of the castings where they reduced the size of grains. However, in the agglomerated form, the graphite particles improved the machinability of copper alloys in a manner similar to lead. The result of the first years work provide an improved method of synthesis of lead free copper graphite alloys with improved machinability and adequate fluidity. Future work will continue to further improve the distribution of graphite particles in casting while retaining adequate fluidity and improved machinability. Techniques like centrifugal casting will be developed to concentrate graphite in regions where it is required for machinability in bearings.

  7. Tunable Graphitic Carbon Nano-Onions Development in Carbon Nanofibers for Multivalent Energy Storage

    SciTech Connect

    Schwarz, Haiqing L.

    2016-01-01

    We developed a novel porous graphitic carbon nanofiber material using a synthesis strategy combining electrospinning and catalytic graphitization. RF hydrogel was used as carbon precursors, transition metal ions were successfully introduced into the carbon matrix by binding to the carboxylate groups of a resorcinol derivative. Transition metal particles were homogeneously distributed throughout the carbon matrix, which are used as in-situ catalysts to produce graphitic fullerene-like nanostructures surrounding the metals. The success design of graphitic carbons with enlarged interlayer spacing will enable the multivalent ion intercalation for the development of multivalent rechargeable batteries.

  8. Preliminary evaluation of graphite in the FMIT test cell

    SciTech Connect

    Morgan, W.C.

    1980-03-01

    A design for the Test Cell of the Fusion Materials Irradiation Test facility includes composite steel-graphite cooling/shielding panels. A graphite damage fluence of about 3.2 x 10/sup 20//cm/sup 2/ at about 80/sup 0/C can be expected over 20 years of operation. This review defines the potential problem areas (stored energy and dimensional changes) and recommends approaches to avoid or alleviate those problems. It is concluded that the design is viable and that no insurmountable problems are likely to be encountered.

  9. Ferric chloride graphite intercalation compounds prepared from graphite fluoride

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh

    1994-01-01

    The reaction between graphite fluoride and ferric chloride was observed in the temperature range of 300 to 400 C. The graphite fluorides used for this reaction have an sp3 electronic structure and are electrical insulators. They can be made by fluorinating either carbon fibers or powder having various degrees of graphitization. Reaction is fast and spontaneous and can occur in the presence of air. The ferric chloride does not have to be predried. The products have an sp2 electronic structure and are electrical conductors. They contain first stage FeCl3 intercalated graphite. Some of the products contain FeCl2*2H2O, others contain FeF3 in concentrations that depend on the intercalation condition. The graphite intercalated compounds (GIC) deintercalated slowly in air at room temperature, but deintercalated quickly and completely at 370 C. Deintercalation is accompanied by the disappearing of iron halides and the formation of rust (hematite) distributed unevenly on the fiber surface. When heated to 400 C in pure N2 (99.99 vol %), this new GIC deintercalates without losing its molecular structure. However, when the compounds are heated to 800 C in quartz tube, they lost most of its halogen atoms and formed iron oxides (other than hematite), distributed evenly in or on the fiber. This iron-oxide-covered fiber may be useful in making carbon-fiber/ceramic-matrix composites with strong bonding at the fiber-ceramic interface.

  10. Ferrix Chloride-Graphite Intercalation Compounds Prepared From Graphite Flouride

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh

    1995-01-01

    The reaction between graphite fluoride and ferric chloride was observed in the temperature range of 300 to 400 C. The graphite fluorides used for this reaction have an sp(sup 3) electronic structure and are electrical insulators. They can be made by fluorinating either carbon fibers or powder having various degrees of graphitization. Reaction is fast and spontaneous and can occur in the presence of air. The ferric chloride does not have to be predried. The products have an sp(sup 2) electronic structure and are electrical conductors. They contain first-stage FeCl3 intercalated graphite. Some of the products contain FeCl2 (center dot) 2H2O, others contain FeF3, in concentrations that depend on the intercalation condition. The graphite intercalated compounds (GIC) deintercalated slowly in air at room temperature, but deintercalated quickly and completely at 370 C. Deintercalation is accompanied by the disappearance of iron halides and the formation of rust (hematite) distributed unevenly on the fiber surface. When heated to 400 C in pure N2 (99.99 vol%), this new GIC deintercalates without losing its molecular structure. However, when the compounds are exposed to 800 C N2, in a quartz tube, they lost most of their halogen atoms and formed iron oxides (other than hematite), distributed evenly in or on the fiber.

  11. Catalyst-free growth of nanocrystalline graphene/graphite patterns from photoresist.

    PubMed

    Zhang, Zengxing; Ge, Binghui; Guo, Yunxian; Tang, Dongsheng; Wang, Xiaojuan; Wang, Fengli

    2013-04-01

    Catalyst-free growth of a nanocrystalline few-layer graphene (or graphite) film from photoresist on variable substrates was demonstrated. The thickness of the film can be easily controlled from 1 nm to hundreds of nanometers. With this method, graphene/graphite patterns with different thicknesses have been designed for integrated electronics. PMID:23439870

  12. Isotropic graphite multistage depressed collectors - A progress report

    NASA Astrophysics Data System (ADS)

    Ramins, Peter; Ebihara, Ben T.

    1989-04-01

    A small isotropic-graphite-electrode multistage depressed collector (MDC) was designed, fabricated, and evaluated in conjunction with a 500-W CW 4.8-9.6-GHz TWT. The carbon electrode surfaces were used to improve the TWT overall efficiency by minimizing the secondary-electron emission losses in the MDC. The design and fabrication of the brazed graphite MDC assembly are described. The TWT and graphite-electrode MDC bakeout and processing (outgassing) characteristics were evaluated and found to be comparable to those for TWTs equipped with copper-electrode MDCs. The TWT and MDC performance was optimized for broadband CW operation at saturation. The average RF, overall, and MDC efficiencies were 14.9, 46.4, and 83.6 percent, respectively, across the octave operating band. A 1500-h CW test showed no gas buildup and excellent stability of the electrode surfaces.

  13. Graphite deposits in Siskiyou County, California

    USGS Publications Warehouse

    Rynearson, Garn A.

    1945-01-01

    The graphite deposits examined are in sec. 7, T. 47 N., R. 11 W., Siskiyou County, Calif., on the summit of the Siskiyou Mts. between Elk Meadow and the northeast end of "mill 6220" (see map of the Seias quadrangle). Four claims, designated as the Black Jack Nos. 1, 2, 3, and 4 claims, and a five-acre mill site have been located by W. H. Gassaway, W. B. Stewart, and E. R. Stewart. Development consists of four small cuts and several shallow trenches.

  14. Graphite Formation in Cast Iron

    NASA Technical Reports Server (NTRS)

    Stefanescu, D. M.

    1985-01-01

    In the first phase of the project it was proven that by changing the ratio between the thermal gradient and the growth rate for commercial cast iron samples solidifying in a Bridgman type furnace, it is possible to produce all types of graphite structures, from flake to spheroidal, and all types of matrices, from ferritic to white at a certain given level of cerium. KC-135 flight experiments have shown that in a low-gravity environment, no flotation occurs even in spheroidal graphite cast irons with carbon equivalent as high as 5%, while extensive graphite flotation occurred in both flake and spheroidal graphite cast irons, in high carbon samples solidified in a high gravity environment. This opens the way for production of iron-carbon composite materials, with high carbon content (e.g., 10%) in a low gravity environment. By using KC-135 flights, the influence of some basic elements on the solidification of cast iron will be studied. The mechanism of flake to spheroidal graphite transition will be studied, by using quenching experiments at both low and one gravity for different G/R ratios.

  15. Development of lead-free copper alloy-graphite castings. Technical report, January 1994--December 1994

    SciTech Connect

    Rohatgi, P.K.

    1995-07-01

    Water model experiments were conducted to develop a two-stage stirring method for obtaining higher yields and a more uniform distribution of graphite particles in copper alloys. This was followed by several melts for synthesis of copper-graphite alloys in which Ti was used as a wetting agent to improve the wettability of graphite in the copper melt. In the first stage, a vortex method was employed to facilitate the addition of graphite particles into the copper melt. In the second stage, a specially designed stirrer was used for uniform particle distribution while avoiding the formation of vortex in the melt. The two-stage stirring was found to considerably improve the recovery of graphite, over those obtained with the prior practice of single-stage stirring and resulting in a more uniform particle distribution. In addition, graphite recoveries increased with increasing Ti content in the range investigated. Floatation, fluidity, and directional solidification experiments were also conducted on copper-graphite alloys synthesized in this study. Fluidity tests showed that the spiral fluidity length of the yellow brass alloy increased with temperature and decreased with graphite. The fluidity of copper-graphite alloys investigated to-date remained adequate to make a variety of castings. The observations of casting microstructure under directional solidification and floatation showed that in certain castings the graphite particles remained agglomerated, and they readily floated to the upper part of the castings where they reduced the size of gains. However, even in the agglomerated form, the graphite particles improved the machinability of copper alloys in a manner similar to lead. The results of the first year work provide an improved method of synthesis of lead free copper graphite alloys with improved machinability and adequate fluidity.

  16. Kinetics of Chronic Oxidation of NBG-17 Nuclear Graphite by Water Vapor

    SciTech Connect

    Contescu, Cristian I; Burchell, Timothy D; Mee, Robert

    2015-05-01

    This report presents the results of kinetic measurements during accelerated oxidation tests of NBG-17 nuclear graphite by low concentration of water vapor and hydrogen in ultra-high purity helium. The objective is to determine the parameters in the Langmuir-Hinshelwood (L-H) equation describing the oxidation kinetics of nuclear graphite in the helium coolant of high temperature gas-cooled reactors (HTGR). Although the helium coolant chemistry is strictly controlled during normal operating conditions, trace amounts of moisture (predictably < 0.2 ppm) cannot be avoided. Prolonged exposure of graphite components to water vapor at high temperature will cause very slow (chronic) oxidation over the lifetime of graphite components. This behavior must be understood and predicted for the design and safe operation of gas-cooled nuclear reactors. The results reported here show that, in general, oxidation by water of graphite NBG-17 obeys the L-H mechanism, previously documented for other graphite grades. However, the characteristic kinetic parameters that best describe oxidation rates measured for graphite NBG-17 are different than those reported previously for grades H-451 (General Atomics, 1978) and PCEA (ORNL, 2013). In some specific conditions, certain deviations from the generally accepted L-H model were observed for graphite NBG-17. This graphite is manufactured in Germany by SGL Carbon Group and is a possible candidate for the fuel elements and reflector blocks of HTGR.

  17. Optical properties of thin graphitic nanopetal arrays

    NASA Astrophysics Data System (ADS)

    Bao, Hua; Kumar, Anurag; Cai, Yuannan; Ji, Yuzhong; Fisher, Timothy S.; Ruan, Xiulin

    2015-06-01

    Thermal radiative properties of thin graphitic petal arrays are theoretically and experimentally investigated. Finite-difference time-domain (FDTD) simulations are first performed to calculate optical properties of vertical graphitic arrays of different structures, namely, graphitic gratings, periodic graphitic cavities, and random graphitic cavities. For graphitic gratings, the absorptance and reflectance are relatively larger when the incident electric field is parallel to the graphitic plane, while the absorptance and reflectance are both significantly lower when the electric field is polarized perpendicular to the graphitic plane. Ordered graphitic petal cavity arrays show optical properties falling between the above two cases of different polarizations. Random vertical cavity arrays with various angles of orientation show similar properties to ordered petal cavities. For oblique gratings, the reflectance will increase with oblique angle for both polarizations, while the absorptance decreases with oblique angle for the in-plane polarization and increases with oblique angle for the out-of-plane polarization. The oblique effects are explained by the strong anisotropic nature of graphitic petals. The FDTD results are compared to effective medium theory to find that the latter describes the optical properties of the graphitic grating and cavity well, and we propose an approach based on effective medium theory to approximate the dielectric function of graphitic petals with random orientation. The predicted hemispherical total reflectance based on this model gives about 2% reflectance in the visible spectrum and agrees well with experimental data from a fabricated graphitic petals sample.

  18. Thermal Pyrolytic Graphite Enhanced Components

    NASA Technical Reports Server (NTRS)

    Hardesty, Robert E. (Inventor)

    2015-01-01

    A thermally conductive composite material, a thermal transfer device made of the material, and a method for making the material are disclosed. Apertures or depressions are formed in aluminum or aluminum alloy. Plugs are formed of thermal pyrolytic graphite. An amount of silicon sufficient for liquid interface diffusion bonding is applied, for example by vapor deposition or use of aluminum silicon alloy foil. The plugs are inserted in the apertures or depressions. Bonding energy is applied, for example by applying pressure and heat using a hot isostatic press. The thermal pyrolytic graphite, aluminum or aluminum alloy and silicon form a eutectic alloy. As a result, the plugs are bonded into the apertures or depressions. The composite material can be machined to produce finished devices such as the thermal transfer device. Thermally conductive planes of the thermal pyrolytic graphite plugs may be aligned in parallel to present a thermal conduction path.

  19. NGNP Graphite Testing and Qualification Specimen Selection Strategy

    SciTech Connect

    Robert Bratton

    2005-05-01

    The available grades of graphite for the NGNP are reviewed. A selection matrix is presented outlining the available grades for the NGNP graphite irradiation program based upon input from potential NGNP vendors, graphite manufactures, and graphite experts.

  20. Graphite fiber reinforced thermoplastic resins

    NASA Technical Reports Server (NTRS)

    Novak, R. C.

    1975-01-01

    Mechanical properties of neat resin samples and graphite fiber reinforced samples of thermoplastic resins were characterized with particular emphasis directed to the effects of environmental exposure (humidity, temperature and ultraviolet radiation). Tensile, flexural, interlaminar shear, creep and impact strengths were measured for polysulfone, polyarylsulfone and a state-of-the-art epoxy resin samples. In general, the thermoplastic resins exhibited environmental degradation resistance equal to or superior to the reference epoxy resin. Demonstration of the utility and quality of a graphite/thermoplastic resin system was accomplished by successfully thermoforming a simulated compressor blade and a fan exit guide vane.

  1. Graphite filament wound pressure vessels

    NASA Technical Reports Server (NTRS)

    Feldman, A.; Damico, J. J.

    1972-01-01

    Filament wound NOL rings, 4-inch and 8-inch diameter closed-end vessels involving three epoxy resin systems and three graphite fibers were tested to develop property data and fabrication technology for filament wound graphite/epoxy pressure vessels. Vessels were subjected to single-cycle burst tests at room temperature. Manufacturing parameters were established for tooling, winding, and curing that resulted in the development of a pressure/vessel performance factor (pressure x volume/weight) or more than 900,000 in. for an oblate spheroid specimen.

  2. Composition and method for brazing graphite to graphite

    DOEpatents

    Taylor, Albert J.; Dykes, Norman L.

    1984-01-01

    The present invention is directed to a brazing material for joining graphite structures that can be used at temperatures up to about 2800.degree. C. The brazing material formed of a paste-like composition of hafnium carbide and uranium oxide with a thermosetting resin. The uranium oxide is converted to uranium dicarbide during the brazing operation and then the hafnium carbide and uranium dicarbide form a liquid phase at a temperature about 2600.degree. C. with the uranium diffusing and vaporizing from the joint area as the temperature is increased to about 2800.degree. C. so as to provide a brazed joint consisting essentially of hafnium carbide. This brazing temperature for hafnium carbide is considerably less than the eutectic temperature of hafnium carbide of about 3150.degree. C. The brazing composition also incorporates the thermosetting resin so that during the brazing operation the graphite structures may be temporarily bonded together by thermosetting the resin so that machining of the structures to final dimensions may be completed prior to the completion of the brazing operation. The resulting brazed joint is chemically and thermally compatible with the graphite structures joined thereby and also provides a joint of sufficient integrity so as to at least correspond with the strength and other properties of the graphite.

  3. Impact damage of a graphite/PEEK

    SciTech Connect

    Demuts, E.

    1994-12-31

    Low-velocity non-penetrating impact has been applied to graphite polyetheretherketone (AS4/APC-2) laminates in accordance with the USAF guidelines for designing damage tolerant primary structures. The extent of delaminations and dent depths for two lay ups and five thicknesses at room temperature and ambient moisture conditions have been determined. Based on these findings as well as those presented elsewhere it may be concluded that the ``softer`` lay up (40/50/10), up to about 75-ply thickness, is more damage tolerant than the ``harder`` lay up (60/30/10) because within this thickness range the ``softer`` lay up displays smaller dent depths, smaller delaminated areas and higher post-impost compressive strength (PICS). For laminates thicker than 75 plies, the relative situation in delamination extent and PICS is reversed, i.e. the ``harder`` lay up is more damage tolerant than the ``softer`` one. The test data obtained in this experimental investigation provide the amount of initial damage to be assumed for a damage tolerant design of USAF primary structures made out of AS4/APC-2 graphite/PEEK. In addition, 9 these data may serve to validate the predictive capability of appropriate analytic models.

  4. Systems and methods for forming defects on graphitic materials and curing radiation-damaged graphitic materials

    DOEpatents

    Ryu, Sunmin; Brus, Louis E.; Steigerwald, Michael L.; Liu, Haitao

    2012-09-25

    Systems and methods are disclosed herein for forming defects on graphitic materials. The methods for forming defects include applying a radiation reactive material on a graphitic material, irradiating the applied radiation reactive material to produce a reactive species, and permitting the reactive species to react with the graphitic material to form defects. Additionally, disclosed are methods for removing defects on graphitic materials.

  5. RECOVERY OF VALUABLE MATERIAL FROM GRAPHITE BODIES

    DOEpatents

    Fromm, L.W. Jr.

    1959-09-01

    An electrolytic process for recovering uranium from a graphite fuel element is described. The uraniumcontaining graphite body is disposed as the anode of a cell containing a nitric acid electrolyte and a 5 amp/cm/sup 2/ current passed to induce a progressive disintegration of the graphite body. The dissolved uranium is quickly and easily separated from the resulting graphite particles by simple mechanical means, such as centrifugation, filtration, and decontamination.

  6. The irradiation dimensional changes of grade TSX graphite

    SciTech Connect

    Kennedy, C R; Woodruff, E M

    1988-01-01

    Grade TSX graphite is used as a moderator in the N Reactor which has operated since 1963. This reactor, designed for a 25-year life, is under study to determine the possibility of significantly extending the operating life. One limiting factor is dimensional growth of the graphite lattice making up the core of the reactor. Since the original demands (25-year life) were modest, the dimensional change behavior was derived from a compendium of irradiation data from other grades and only confirmed by a few low-exposure irradiation experiments. Therefore, to generate actual dimensional change data for grade TSX to exposures relevant to the life extension plans, a series of irradiations of TSX graphite were run in the High Flux Isotope Reactor (HFIR) at Oak Ridge. This report contains experimental results of such testing. 5 refs., 3 figs.

  7. Practical Aspects for Characterizing Air Oxidation of Graphite

    SciTech Connect

    Contescu, Cristian I; Azad, Samina; Miller, Doug; Lance, Michael J; Baker, Frederick S; Burchell, Timothy D

    2008-01-01

    The efforts for designing of a meaningful and acceptable standard test method for characterization of kinetic parameters of air oxidation of graphite helped identify several practical issues that must be considered for the development of such a test. Using standard size (and shape) specimens, large enough in size to accommodate the inherent local microstructure differences between graphite samples, resulted in non-uniform oxidation profiles and preferential binder oxidation; this was not expected based on the linearity of Arrhenius plots and the (large) values of activation energy. It was found that the transition between the regimes 1 and 2 of graphite oxidation occurs gradually, depending both on the oxidation temperature and rate of oxygen supply. Nevertheless, measuring oxidation rates obtained on standard size samples provides a basis for a meaningful comparison among materials, which may serve as much needed information for predictive models.

  8. Development of lightweight graphite/polyimide sandwich panels.

    NASA Technical Reports Server (NTRS)

    Poesch, J. G.

    1972-01-01

    Lightweight graphite/polyimide composite honeycomb core and sandwich panels were fabricated and tested. Honeycomb cores of 1/4-in. and 3/8-in. cell sizes of hexagonal configuration were produced from thin plus or minus 45 deg cross plied sheets of prepreg producing core weights between 1.8 and 3.6 lb/cu ft. Thin gauge prepreg using Hercules graphite tow and Monsanto Skybond 710 polyimide resin were manufactured to produce cured ply thicknesses of 0.001 to 0.002 in. Graphite core properties measured at temperatures from -150 to 600 F are reported. Core properties which are superior to available materials were obtained. Sandwich panels weighing less than 0.5 lb/sq ft were designed and fabricated which meet the support structure loads for the shuttle orbiter thermal protection system.

  9. High speed hydrogen/graphite interaction

    NASA Technical Reports Server (NTRS)

    Kelly, A. J.; Hamman, R.; Sharma, O. P.; Harrje, D. T.

    1974-01-01

    Various aspects of a research program on high speed hydrogen/graphite interaction are presented. Major areas discussed are: (1) theoretical predictions of hydrogen/graphite erosion rates; (2) high temperature, nonequilibrium hydrogen flow in a nozzle; and (3) molecular beam studies of hydrogen/graphite erosion.

  10. CMB-13 research on carbon and graphite

    NASA Technical Reports Server (NTRS)

    Smith, M. C.

    1972-01-01

    The research on graphite and carbon for this period is reported. Topics discussed include: effects of grinding on the Santa Marie graphites, properties and purities of coal-tar, resin-bonded graphite, carbonization of resin components, and glass-like carbon filler.

  11. Separation medium containing thermally exfoliated graphite oxide

    NASA Technical Reports Server (NTRS)

    Prud'homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor); Herrera-Alonso, Margarita (Inventor)

    2012-01-01

    A separation medium, such as a chromatography filling or packing, containing a modified graphite oxide material, which is a thermally exfoliated graphite oxide with a surface area of from about 300 m.sup.2/g to 2600 m.sup.2/g, wherein the thermally exfoliated graphite oxide has a surface that has been at least partially functionalized.

  12. Method of Joining Graphite Fibers to a Substrate

    NASA Technical Reports Server (NTRS)

    Beringer, Durwood M. (Inventor); Caron, Mark E. (Inventor); Taddey, Edmund P. (Inventor); Gleason, Brian P. (Inventor)

    2014-01-01

    A method of assembling a metallic-graphite structure includes forming a wetted graphite subassembly by arranging one or more layers of graphite fiber material including a plurality of graphite fibers and applying a layer of metallization material to ends of the plurality of graphite fibers. At least one metallic substrate is secured to the wetted graphite subassembly via the layer of metallization material.

  13. High-strain-rate characterization of TPOs and graphite/epoxy and graphite/peek composites

    NASA Astrophysics Data System (ADS)

    Brar, N. S.; Simha, H.; Pratap, A.

    2001-06-01

    Tensile and compressive stress-strain response of two types of TPOs and graphite-epoxy composites are investigated at strain rates in the range 0.001/s-1000/s. Specimen strain in the low strain rate regime 0.001-100/s was determined using an optical extensometer in conjunction with standard MTS machine. Tensile test at high strain rate were performed on newly developed tensile version of All- Polymeric Split Hopkinson Bar. Tensile TPO specimens in the dog-bone configuration are placed in specially designed grips fabricated from nylatron. Compression response of TPO specimens at high strain rate is determined using 25.4-mm diameter aluminum bars. Peak compressive stress increases from 10 MPa at a strain rate of 100/s to 35 MPa at a strain rate of 1000/s. Preliminary data on high strain rate tensile response of graphite-epoxy and graphite-peek composites are presented. These data are intended to develop a material model incorporating strain rate sensitivity for TPOs and to be used in car crash simulations.

  14. Strength of modified carbon-graphite composites

    SciTech Connect

    Bolotina, K.S.; Shchugorev, V.N.

    1995-01-01

    Composite materials are being more and more widely used in the nontraditional power generation fields, particularly in powerplants using the ecologically clean energy sources (solar, wind, and tidal plants). The less expensive composites are preferred. Requirements of a functional nature are usually imposed on the composites: high (or low) thermal conductivity and high electroconductive (or electroinsulative) properties. At the same time, many powerplant components act as load-carrying structures and require analysis of their mechnical reliability and service life. Because of the considerable intrinsic mass (for large structures) and the wind, snow, and wave loads with long periods of operation, the mechnical analysis is a critical part of the design process. Various modification techniques are used to obtain materials with the required combination of mechanical, thermophysical, and electrical properties on the basis of the inexpensive composites. These techniques include modification of the properties of the binders by selecting the curing technique and introducing additives to the binder, and also the use of composites containing a quite high percentage of modifiers - metallic powders, ferromagnetics, ferroelectrics, and so on. The authors have studied the influence of the modifiers on the mechanical properties of the carbon-graphite composites that are created on the basis of powdered carbon-graphites and phenolformaldehyde resins. Such composites are already used in the heat engineering field. The carbon-graphite materials are obtained from a mixture of pulverized coke and coal tar with subsequent pressing into rod or blocks, which are sintered at 1200{degrees}C in air-free furnaces.

  15. Graphite oral tattoo: case report.

    PubMed

    Moraes, Renata Mendonça; Gouvêa Lima, Gabriela de Morais; Guilhermino, Marinaldo; Vieira, Mayana Soares; Carvalho, Yasmin Rodarte; Anbinder, Ana Lia

    2015-10-01

    Pigmented oral lesions compose a large number of pathological entities, including exogenous pigmentat oral tattoos, such as amalgam and graphite tattoos. We report a rare case of a graphite tattoo on the palate of a 62-year-old patient with a history of pencil injury, compare it with amalgam tattoos, and determine the prevalence of oral tattoos in our Oral Pathology Service. We also compare the clinical and histological findings of grafite and amalgam tattoos. Oral tattoos affect women more frequently in the region of the alveolar ridge. Graphite tattoos occur in younger patients when compared with the amalgam type. Histologically, amalgam lesions represent impregnation of the reticular fibers of vessels and nerves with silver, whereas in cases of graphite tattoos, this impregnation is not observed, but it is common to observe a granulomatous inflammatory response, less evident in cases of amalgam tattoos. Both types of lesions require no treatment, but in some cases a biopsy may be done to rule out melanocytic lesions. PMID:26632800

  16. Igneous Graphite in Enstatite Chondrites

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.

    1997-01-01

    Igneous graphite. a rare constituent in terrestrial mafic and ultramafic rocks. occurs in three EH and one EL enstatite chondrite impact-melt breccias as 2-150 Ilm long euhedrallaths. some with pyramidal terminations. In contrast. graphite in most enstatite chondrites exsolved from metallic Fe-Ni as polygonal. rounded or irregular aggregates. Literature data for five EH chondrites on C combusting at high temperatures show that Abee contains the most homogeneous C isotopes (i.e. delta(sup 13)C = -8.1+/-2.1%); in addition. Abee's mean delta(sup l3)C value is the same as the average high-temperature C value for the set of five EH chondrites. This suggests that Abee scavenged C from a plurality of sources on its parent body and homogenized the C during a large-scale melting event. Whereas igneous graphite in terrestrial rocks typically forms at relatively high pressure and only moderately low oxygen fugacity (e.g., approx. 5 kbar. logfO2, approx. -10 at 1200 C ). igneous graphite in asteroidal meteorites formed at much lower pressures and oxygen fugacities.

  17. Fracture toughness of anisotropic graphites

    SciTech Connect

    Kennedy, C.R.; Kehne, M.T.

    1985-01-01

    Fracture toughness measurements have been made at 0, 30, 45, 60, and 90/sup 0/ from the extrusion axis on a reasonably anisotropic graphite, grade AGOT. It was found that the fracture toughness did not vary appreciably with orientation. An observed variation in strength was found to be the result of defect orientation.

  18. Treatment of Irradiated Graphite from French Bugey Reactor - 13424

    SciTech Connect

    Brown, Thomas; Poncet, Bernard

    2013-07-01

    Beginning in 2009, in order to determine an alternative to direct disposal for decommissioned irradiated graphite from EDF's Bugey NPP, Studsvik and EDF began a test program to determine if graphite decontamination and destruction were practicable using Studsvik's thermal organic reduction (THOR) technology. The testing program focused primarily on the release of C-14, H-3, and Cl-36 and also monitored graphite mass loss. For said testing, a bench-scale steam reformer (BSSR) was constructed with the capability of flowing various compositions of gases at temperatures up to 1300 deg. C over uniformly sized particles of graphite for fixed amounts of time. The BSSR was followed by a condenser, thermal oxidizer, and NaOH bubbler system designed to capture H-3 and C-14. Also, in a separate series of testing, high concentration acid and peroxide solutions were used to soak the graphite and leach out and measure Cl-36. A series of gasification tests were performed to scope gas compositions and temperatures for graphite gasification using steam and oxygen. Results suggested higher temperature steam (1100 deg. C vs. 900 deg. C) yielded a practicable gasification rate but that lower temperature (900 deg. C) gasification was also a practicable treatment alternative if oxygen is fed into the process. A series of decontamination tests were performed to determine the release behavior of and extent to which C-14 and H-3 were released from graphite in a high temperature (900-1300 deg. C), low flow roasting gas environment. In general, testing determined that higher temperatures and longer roasting times were efficacious for releasing H-3 completely and the majority (80%) of C-14. Manipulating oxidizing and reducing gas environments was also found to limit graphite mass loss. A series of soaking tests was performed to measure the amount of Cl-36 in the samples of graphite before and after roasting in the BSSR. Similar to C-14 release, these soaking tests revealed that 70-80% Cl-36

  19. Reinforcement of cement-based matrices with graphite nanomaterials

    NASA Astrophysics Data System (ADS)

    Sadiq, Muhammad Maqbool

    micro-scale fibers were used for comparison purposes at different volume fractions. Replicated mixes and tests were considered to provide the basis for statistically reliable inferences. Theoretical studies were conducted in order to develop insight into the reinforcement mechanisms of properly functionalized graphite nanomaterials. The results suggested that modified graphite nanomaterials improve the mechanical performance of cement-based matrices primarily through control of microcrack size and propagation, relying on their close spacing within matrix and dissipation of substantial energy by debonding and frictional pullout over their enormous surface areas. The gains in barrier qualities of cement-based materials with introduction of modified graphite nanomaterials could be attributed to the increased tortuosity of diffusion paths in the presence of closely spaced nanomaterials. Experimental investigations were designed and implemented towards identification of the optimum (nano- and micro-scale) reinforcement systems for high-performance concrete through RSA (Response Surface Analysis). A comprehensive experimental data base was developed on the mechanical, physical and durability characteristics as well as the structure and composition of high-performance cementitious nanocomposites reinforced with modified graphite nanomaterials and/ or different micro-fibers.

  20. Progress in Developing Finite Element Models Replicating Flexural Graphite Testing

    SciTech Connect

    Robert Bratton

    2010-06-01

    This report documents the status of flexural strength evaluations from current ASTM procedures and of developing finite element models predicting the probability of failure. This work is covered under QLD REC-00030. Flexural testing procedures of the American Society for Testing and Materials (ASTM) assume a linear elastic material that has the same moduli for tension and compression. Contrary to this assumption, graphite is known to have different moduli for tension and compression. A finite element model was developed and demonstrated that accounts for the difference in moduli tension and compression. Brittle materials such as graphite exhibit significant scatter in tensile strength, so probabilistic design approaches must be used when designing components fabricated from brittle materials. ASTM procedures predicting probability of failure in ceramics were compared to methods from the current version of the ASME graphite core components rules predicting probability of failure. Using the ASTM procedures yields failure curves at lower applied forces than the ASME rules. A journal paper was published in the Journal of Nuclear Engineering and Design exploring the statistical models of fracture in graphite.

  1. Orientation relationships in graphitic cast irons

    NASA Astrophysics Data System (ADS)

    Kim, Sooho; Phillips, D. S.

    1987-11-01

    Ferrite/graphite and martensite/graphite interfaces in three commercial cast irons have been analyzed using transmission electron microscopy. Two recurring orientation relationships have been found to account for over 60 pct of the ferrite/graphite interfaces analyzed. A similar pair of relationships discovered in martensitic material strongly suggests that the prior austenite/graphite interface was also ordered. The same relationships were prominent in gray and ductile irons. One of the relationships observed can be transformed through the Kurdjumov-Sachs relationship to a previously-reported austenite/graphite relationship.

  2. Optimized Conditioning of Activated Reactor Graphite

    SciTech Connect

    Tress, G.; Doehring, L.; Pauli, H.; Beer, H.-F.

    2002-02-25

    The research reactor DIORIT at the Paul Scherrer Institute was decommissioned in 1993 and is now being dismantled. One of the materials to be conditioned is activated reactor graphite, approximately 45 tons. A cost effective conditioning method has been developed. The graphite is crushed to less than 6 mm and added to concrete and grout. This graphite concrete is used as matrix for embedding dismantling waste in containers. The waste containers that would have been needed for separate conditioning and disposal of activated reactor graphite are thus saved. Applying the new method, the cost can be reduced from about 55 SFr/kg to about 17 SFr/kg graphite.

  3. Research on graphite reinforced glass matrix composites

    NASA Technical Reports Server (NTRS)

    Bacon, J. F.; Prewo, K. M.

    1977-01-01

    The results of research for the origination of graphite-fiber reinforced glass matrix composites are presented. The method selected to form the composites consisted of pulling the graphite fiber through a slurry containing powdered glass, winding up the graphite fiber and the glass it picks up on a drum, drying, cutting into segments, loading the tape segment into a graphite die, and hot pressing. During the course of the work, composites were made with a variety of graphite fibers in a glass matrix.

  4. Ag-catalyzed InAs nanowires grown on transferable graphite flakes

    NASA Astrophysics Data System (ADS)

    Meyer-Holdt, Jakob; Kanne, Thomas; Sestoft, Joachim E.; Gejl, Aske; Zeng, Lunjie; Johnson, Erik; Olsson, Eva; Nygård, Jesper; Krogstrup, Peter

    2016-09-01

    Semiconducting nanowires grown by quasi-van-der-Waals epitaxy on graphite flakes are a new class of hybrid materials that hold promise for scalable nanostructured devices within opto-electronics. Here we report on high aspect ratio and stacking fault free Ag-seeded InAs nanowires grown on exfoliated graphite flakes by molecular beam epitaxy. Ag catalyzes the InAs nanowire growth selectively on the graphite flakes and not on the underlying InAs substrates. This allows for easy transfer of the flexible graphite flakes with as-grown nanowire ensembles to arbitrary substrates by a micro-needle manipulator. Besides the possibilities for fabricating novel nanostructure device designs, we show how this method is used to study the parasitic growth and bicrystal match between the graphite flake and the nanowires by transmission electron microscopy.

  5. Investigation of the strength of H440 graphite when subjected to combined primary and secondary stress

    SciTech Connect

    Anderson, C.A.; Fly, G.W.; Lundberg, L.B.; Romero, J.A.

    1986-04-01

    An experimental and analytical investigation of the strength of a fine-grained graphite, H440, under combined mechanical and thermal stress is described. Small sample laboratory tests were carried out to establish a mechanical property data base from which statistical parameters could be determined and then used in finite element codes for predicting failure probabilities of large graphite structural components under load. The theory was applied to graphite rings under an imposed thermal stress from a heat flux applied to the inner surface of the rings and under mechhanical stress caused by diametrically opposed concentrated loads applied to the outer surface of the rings. Rings of H440 graphite were fabricated in two sizes and tested to the combined thermal and mechanical loadings. From the results of theory and the experiments, a design rule for combining mechanical and thermal stress in graphite structural components is proposed.

  6. Ag-catalyzed InAs nanowires grown on transferable graphite flakes.

    PubMed

    Meyer-Holdt, Jakob; Kanne, Thomas; Sestoft, Joachim E; Gejl, Aske; Zeng, Lunjie; Johnson, Erik; Olsson, Eva; Nygård, Jesper; Krogstrup, Peter

    2016-09-01

    Semiconducting nanowires grown by quasi-van-der-Waals epitaxy on graphite flakes are a new class of hybrid materials that hold promise for scalable nanostructured devices within opto-electronics. Here we report on high aspect ratio and stacking fault free Ag-seeded InAs nanowires grown on exfoliated graphite flakes by molecular beam epitaxy. Ag catalyzes the InAs nanowire growth selectively on the graphite flakes and not on the underlying InAs substrates. This allows for easy transfer of the flexible graphite flakes with as-grown nanowire ensembles to arbitrary substrates by a micro-needle manipulator. Besides the possibilities for fabricating novel nanostructure device designs, we show how this method is used to study the parasitic growth and bicrystal match between the graphite flake and the nanowires by transmission electron microscopy. PMID:27479073

  7. Composition and method for brazing graphite to graphite

    DOEpatents

    Taylor, A.J.; Dykes, N.L.

    1982-08-10

    A brazing material is described for joining graphite structures that can be used up to 2800/sup 0/C. The brazing material is formed of a paste-like composition of hafnium carbide and uranium oxide with a thermosetting resin. The uranium oxide is converted to uranium dicarbide during the brazing operation and then the hafnium carbide and uranium dicarbide form a liquid phase at a temperature about 2600/sup 0/C with the uranium diffusing and vaporizing from the joint area as the temperature is increased to about 2800/sup 0/C so as to provide a brazed joint consisting essentially of hafnium carbide. The resulting brazed joint is chemically and thermally compatible with the graphite structures.

  8. Graphite Foam Heat Exchangers for Thermal Management

    SciTech Connect

    Klett, J.W.

    2004-06-07

    Improved thermal management is needed to increase the power density of electronic and more effectively cool electronic enclosures that are envisioned in future aircraft, spacecraft and surface ships. Typically, heat exchanger cores must increase in size to more effectively dissipate increased heat loads, this would be impossible in many cases, thus improved heat exchanger cores will be required. In this Phase I investigation, MRi aimed to demonstrate improved thermal management using graphite foam (Gr-foam) core heat exchangers. The proposed design was to combine Gr-foams from POCO with MRi's innovative low temperature, active metal joining process (S-Bond{trademark}) to bond Gr-foam to aluminum, copper and aluminum/SiC composite faceplates. The results were very favorable, so a Phase II SBIR with the MDA was initiated. This had primarily 5 tasks: (1) bonding, (2) thermal modeling, (3) cooling chip scale packages, (4) evaporative cooling techniques and (5) IGBT cold plate development. The bonding tests showed that the ''reflow'' technique with S-Bond{reg_sign}-220 resulted in the best and most consistent bond. Then, thermal modeling was used to design different chip scale packages and IGBT cold plates. These designs were used to fabricate many finned graphite foam heat sinks specifically for two standard type IC packages, the 423 and 478 pin chips. These results demonstrated several advantages with the foam. First, the heat sinks with the foam were lighter than the copper/aluminum sinks used as standards. The sinks for the 423 design made from foam were not as good as the standard sinks. However, the sinks made from foam for the 478 pin chips were better than the standard heat sinks used today. However, this improvement was marginal (in the 10-20% better regime). However, another important note was that the epoxy bonding technique resulted in heat sinks with similar results as that with the S-bond{reg_sign}, slightly worse than the S-bond{reg_sign}, but still

  9. Graphite moderated (252)Cf source.

    PubMed

    Sajo-Bohus, Laszlo; Barros, Haydn; Greaves, Eduardo D; Vega-Carrillo, Hector Rene

    2015-06-01

    The Thorium molten-salt reactor is an attractive and affordable nuclear power option for developing countries with insufficient infrastructure and limited technological capability. In the aim of personnel training and experience gathering at the Universidad Simon Bolivar there is in progress a project of developing a subcritical thorium liquid-fuel reactor. The neutron source to run this subcritical reactor is a (252)Cf source and the reactor will use high-purity graphite as moderator. Using the MCNP5 code the neutron spectra of the (252)Cf in the center of the graphite moderator has been estimated along the channel where the liquid thorium salt will be inserted; also the ambient dose equivalent due to the source has been determined around the moderator. PMID:25770393

  10. Universal Optical Conductance of Graphite

    SciTech Connect

    Kuzmenko, A. B.; Heumen, E. van; Carbone, F.; Marel, D. van der

    2008-03-21

    We find experimentally that the optical sheet conductance of graphite per graphene layer is very close to ({pi}/2)e{sup 2}/h, which is the theoretically expected value of dynamical conductance of isolated monolayer graphene. Our calculations within the Slonczewski-Weiss-McClure model explain well why the interplane hopping leaves the conductance of graphene sheets in graphite almost unchanged for photon energies between 0.1 and 0.6 eV, even though it significantly affects the band structure on the same energy scale. The f-sum rule analysis shows that the large increase of the Drude spectral weight as a function of temperature is at the expense of the removed low-energy optical spectral weight of transitions between hole and electron bands.

  11. 3D-graphite structure

    SciTech Connect

    Belenkov, E. A. Ali-Pasha, V. A.

    2011-01-15

    The structure of clusters of some new carbon 3D-graphite phases have been calculated using the molecular-mechanics methods. It is established that 3D-graphite polytypes {alpha}{sub 1,1}, {alpha}{sub 1,3}, {alpha}{sub 1,5}, {alpha}{sub 2,1}, {alpha}{sub 2,3}, {alpha}{sub 3,1}, {beta}{sub 1,2}, {beta}{sub 1,4}, {beta}{sub 1,6}, {beta}{sub 2,1}, and {beta}{sub 3,2} consist of sp{sup 2}-hybridized atoms, have hexagonal unit cells, and differ in regards to the structure of layers and order of their alternation. A possible way to experimentally synthesize new carbon phases is proposed: the polymerization and carbonization of hydrocarbon molecules.

  12. Poco Graphite Mirror Metrology Report

    NASA Technical Reports Server (NTRS)

    Kester, Thomas J.

    2005-01-01

    Recently a lightweight mirror technology was tested at Marshall Space Flight Center's Space Optic Manufacturing Technology Center (MSFC, SOMTC). The mirror is a Poco Graphite CVD Si clad SiC substrate. It was tested for cryogenic (cryo) survivability to 20deg Kelvin in SOMTC's X-ray Calibration and Cryogenic Test Facility. The surface figure of the mirror was measured before and after cry0 cycling. The test technique and results are discussed.

  13. Graphite Nanoreinforcements for Aerospace Nanocomposites

    NASA Technical Reports Server (NTRS)

    Drzal, Lawrence T.

    2005-01-01

    New advances in the reinforcement of polymer matrix composite materials are critical for advancement of the aerospace industry. Reinforcements are required to have good mechanical and thermal properties, large aspect ratio, excellent adhesion to the matrix, and cost effectiveness. To fulfill the requirements, nanocomposites in which the matrix is filled with nanoscopic reinforcing phases having dimensions typically in the range of 1nm to 100 nm show considerably higher strength and modulus with far lower reinforcement content than their conventional counterparts. Graphite is a layered material whose layers have dimensions in the nanometer range and are held together by weak Van der Waals forces. Once these layers are exfoliated and dispersed in a polymer matrix as nano platelets, they have large aspect ratios. Graphite has an elastic modulus that is equal to the stiffest carbon fiber and 10-15 times that of other inorganic reinforcements, and it is also electrically and thermally conductive. If the appropriate surface treatment can be found for graphite, its exfoliation and dispersion in a polymer matrix will result in a composite with excellent mechanical properties, superior thermal stability, and very good electrical and thermal properties at very low reinforcement loadings.

  14. Development of polyphenylquinoxaline graphite composites

    NASA Technical Reports Server (NTRS)

    Hoggatt, J. T.; Hergenrother, P. M.; Shdo, J. G.

    1973-01-01

    The potential of polyphenylquinoxaline (PPQ)/graphite composites to serve as structural material at 316 C (600 F)has been demonstrated using a block copolymer, BlCo(13), PPQ derivative. Initially, thirteen polyphenylquinoxalines were evaluated. From this work, four candidate polymers were selected for preliminary evaluation as matrices for HMS graphite fiber reinforced composites. The preliminary composite evaluation enabled selection of one of the four polymers for advanced composite preparation and testing. Using an experimentally established cure schedule for each of the four polymers, preliminary laminates of 50% resin volume content, prepared without postcure, were tested for flexure strength and modulus, interlaminar shear strength (short beam), and tensile strength and modulus at ambient temperature. A block copolymer (Bl Co 13) derived from one mole p-bis (phenylglyoxalyl) benzene, one fourth mole 3,3'-diaminobenzidine and three-fourths mole 3,3', 4,4'-tetraminobenzophenone was selected for extensive study. Tensile, flexural, and interlaminar shear values were obtained after aging and testing postcured BlCo(13) laminates at 316 C (600 F). The potential of PPQ/graphite laminates to serve as short term structural materials at temperatures up to 371 C (700 F) was demonstrated through weight loss experiments.

  15. Electrochemical Ultracapacitors Using Graphitic Nanostacks

    NASA Technical Reports Server (NTRS)

    Marotta, Christopher

    2012-01-01

    Electrochemical ultracapacitors (ECs) have been developed using graphitic nanostacks as the electrode material. The advantages of this technology will be the reduction of device size due to superior power densities and relative powers compared to traditional activated carbon electrodes. External testing showed that these materials display reduced discharge response times compared to state-of-the-art materials. Such applications are advantageous for pulsed power applications such as burst communications (satellites, cell phones), electromechanical actuators, and battery load leveling in electric vehicles. These carbon nanostructures are highly conductive and offer an ordered mesopore network. These attributes will provide more complete electrolyte wetting, and faster release of stored charge compared to activated carbon. Electrochemical capacitor (EC) electrode materials were developed using commercially available nanomaterials and modifying them to exploit their energy storage properties. These materials would be an improvement over current ECs that employ activated carbon as the electrode material. Commercially available graphite nanofibers (GNFs) are used as precursor materials for the synthesis of graphitic nanostacks (GNSs). These materials offer much greater surface area than graphite flakes. Additionally, these materials offer a superior electrical conductivity and a greater average pore size compared to activated carbon electrodes. The state of the art in EC development uses activated carbon (AC) as the electrode material. AC has a high surface area, but its small average pore size inhibits electrolyte ingress/egress. Additionally, AC has a higher resistivity, which generates parasitic heating in high-power applications. This work focuses on fabricating EC from carbon that has a very different structure by increasing the surface area of the GNF by intercalation or exfoliation of the graphitic basal planes. Additionally, various functionalities to the GNS

  16. INITIAL COMPARISON OF BASELINE PHYSICAL AND MECHANICAL PROPERTIES FOR THE VHTR CANDIDATE GRAPHITE GRADES

    SciTech Connect

    Carroll, Mark C

    2014-09-01

    High-purity graphite is the core structural material of choice in the Very High Temperature Reactor (VHTR) design, a graphite-moderated, helium-cooled configuration that is capable of producing thermal energy for power generation as well as process heat for industrial applications that require temperatures higher than the outlet temperatures of present nuclear reactors. The Baseline Graphite Characterization Program is endeavoring to minimize the conservative estimates of as-manufactured mechanical and physical properties in nuclear-grade graphites by providing comprehensive data that captures the level of variation in measured values. In addition to providing a thorough comparison between these values in different graphite grades, the program is also carefully tracking individual specimen source, position, and orientation information in order to provide comparisons both in specific properties and in the associated variability between different lots, different billets, and different positions from within a single billet. This report is a preliminary comparison between each of the grades of graphite that are considered “candidate” grades from four major international graphite producers. These particular grades (NBG-18, NBG-17, PCEA, IG-110, and 2114) are the major focus of the evaluations presently underway on irradiated graphite properties through the series of Advanced Graphite Creep (AGC) experiments. NBG-18, a medium-grain pitch coke graphite from SGL from which billets are formed via vibration molding, was the favored structural material in the pebble-bed configuration. NBG-17 graphite from SGL is essentially NBG-18 with the grain size reduced by a factor of two. PCEA, petroleum coke graphite from GrafTech with a similar grain size to NBG-17, is formed via an extrusion process and was initially considered the favored grade for the prismatic layout. IG-110 and 2114, from Toyo Tanso and Mersen (formerly Carbone Lorraine), respectively, are fine-grain grades

  17. Measurement of damping of graphite epoxy materials

    NASA Technical Reports Server (NTRS)

    Crocker, M. J.

    1985-01-01

    The design of an experiment to measure the damping of a cylindrical graphite-epoxy specimen with a three point support and a knife edge support is described as well as equipment used in tests conducted to determine the influence of the support at the two ends of the specimen and to simulate an idealized free-free boundary condition at the two edges. A curve fitting technique is being used to process the frequency response data obtained. Experiments conducted on the thin plate specimen also reveal the influence of the end support condition on the damping ratio of the specimen. The damping ratio values measured for both specimens appear to be strongly influenced by the shape of the specimen and appear to depend on length and fiber orientation as well as the presence of discontinuities such as sharp bends, corners, and notches.

  18. On residual gas analysis during high temperature baking of graphite tiles

    NASA Astrophysics Data System (ADS)

    Prakash, A. A.; Chaudhuri, P.; Khirwadkar, S.; Chauhan, N.; Raole, P. M.; Reddy, D. Chenna; Saxena, Y. C.

    2008-05-01

    Steady-state Super-conducting Tokamak-1 (SST-1) is a medium size tokamak with major radius of 1.1 m and minor radius of 0.20 m. It is designed for plasma discharge duration of 1000 seconds to obtain fully steady-state plasma operation. Plasma Facing Components (PFC), consisting of divertors, passive stabilizers, baffles and poloidal limiters are also designed to be UHV compatible for steady state operation. All PFC are made up of graphite tiles mechanically attached to the copper alloy substrate. Graphite is one of the preferred first wall armour material in present day tokamaks. High thermal shock resistance and low atomic number of carbon are the most important properties of graphite for this application. High temperature vacuum baking of graphite tiles is the standard process to remove the impurities. Residual Gas Analyzer (RGA) has been used for qualitative and quantitative measurements of released gases from graphite tiles during baking. Surface Analysis of graphite tiles has also been done before and after baking. This paper describes the residual gas analysis during baking and surface analysis of graphite tiles.

  19. Thermal charging study of compressed expanded natural graphite/phase change material composites

    DOE PAGESBeta

    Mallow, Anne; Abdelaziz, Omar; Graham, Jr., Samuel

    2016-08-12

    The thermal charging performance of paraffin wax combined with compressed expanded natural graphite foam was studied for different graphite bulk densities. Constant heat fluxes between 0.39 W/cm2 and 1.55 W/cm2 were applied, as well as a constant boundary temperature of 60 °C. Thermal charging experiments indicate that, in the design of thermal batteries, thermal conductivity of the composite alone is an insufficient metric to determine the influence of the graphite foam on the thermal energy storage. By dividing the latent heat of the composite by the time to end of melt for each applied boundary condition, the energy storage performancemore » was calculated to show the effects of composite thermal conductivity, graphite bulk density, and latent heat capacity. For the experimental volume, the addition of graphite beyond a graphite bulk density of 100 kg/m3 showed limited benefit on the energy storage performance due to the decrease in latent heat storage capacity. These experimental results are used to validate a numerical model to predict the time to melt and for future use in the design of heat exchangers with graphite-foam based phase change material composites. As a result, size scale effects are explored parametrically with the validated model.« less

  20. Environmentally benign graphite intercalation compound composition for exfoliated graphite, flexible graphite, and nano-scaled graphene platelets

    DOEpatents

    Zhamu, Aruna; Jang, Bor Z.

    2014-06-17

    A carboxylic-intercalated graphite compound composition for the production of exfoliated graphite, flexible graphite, or nano-scaled graphene platelets. The composition comprises a layered graphite with interlayer spaces or interstices and a carboxylic acid residing in at least one of the interstices, wherein the composition is prepared by a chemical oxidation reaction which uses a combination of a carboxylic acid and hydrogen peroxide as an intercalate source. Alternatively, the composition may be prepared by an electrochemical reaction, which uses a carboxylic acid as both an electrolyte and an intercalate source. Exfoliation of the invented composition does not release undesirable chemical contaminants into air or drainage.

  1. Pyrolytic graphite gauge for measuring heat flux

    NASA Technical Reports Server (NTRS)

    Bunker, Robert C. (Inventor); Ewing, Mark E. (Inventor); Shipley, John L. (Inventor)

    2002-01-01

    A gauge for measuring heat flux, especially heat flux encountered in a high temperature environment, is provided. The gauge includes at least one thermocouple and an anisotropic pyrolytic graphite body that covers at least part of, and optionally encases the thermocouple. Heat flux is incident on the anisotropic pyrolytic graphite body by arranging the gauge so that the gauge surface on which convective and radiative fluxes are incident is perpendicular to the basal planes of the pyrolytic graphite. The conductivity of the pyrolytic graphite permits energy, transferred into the pyrolytic graphite body in the form of heat flux on the incident (or facing) surface, to be quickly distributed through the entire pyrolytic graphite body, resulting in small substantially instantaneous temperature gradients. Temperature changes to the body can thereby be measured by the thermocouple, and reduced to quantify the heat flux incident to the body.

  2. Uranium Oxide Aerosol Transport in Porous Graphite

    SciTech Connect

    Blanchard, Jeremy; Gerlach, David C.; Scheele, Randall D.; Stewart, Mark L.; Reid, Bruce D.; Gauglitz, Phillip A.; Bagaasen, Larry M.; Brown, Charles C.; Iovin, Cristian; Delegard, Calvin H.; Zelenyuk, Alla; Buck, Edgar C.; Riley, Brian J.; Burns, Carolyn A.

    2012-01-23

    The objective of this paper is to investigate the transport of uranium oxide particles that may be present in carbon dioxide (CO2) gas coolant, into the graphite blocks of gas-cooled, graphite moderated reactors. The transport of uranium oxide in the coolant system, and subsequent deposition of this material in the graphite, of such reactors is of interest because it has the potential to influence the application of the Graphite Isotope Ratio Method (GIRM). The GIRM is a technology that has been developed to validate the declared operation of graphite moderated reactors. GIRM exploits isotopic ratio changes that occur in the impurity elements present in the graphite to infer cumulative exposure and hence the reactor’s lifetime cumulative plutonium production. Reference Gesh, et. al., for a more complete discussion on the GIRM technology.

  3. METHOD FOR COATING GRAPHITE WITH METALLIC CARBIDES

    DOEpatents

    Steinberg, M.A.

    1960-03-22

    A method for producing refractory coatings of metallic carbides on graphite was developed. In particular, the graphite piece to be coated is immersed in a molten solution of 4 to 5% by weight of zirconium, titanium, or niobium dissolved in tin. The solution is heated in an argon atmosphere to above 1400 deg C, whereby the refractory metal reacts with the surface of the graphite to form a layer of metalic carbide. The molten solution is cooled to 300 to 400 deg C, and the graphite piece is removed. Excess tin is wiped from the graphite, which is then heated in vacuum to above 2300 deg C. The tin vaporizes from the graphite surface, leaving the surface coated with a tenacious layer of refractory metallic carbide.

  4. Preliminary economic evaluation of the use of graphite composite materials in surface transportation, phase 1 results

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Composite materials are discussed with emphasis on the identification of the characteristics of those materials that make them attractive for use in surface transportation. Potential uses of graphite composites are given including automotive applications and the effects of materials substitution on vehicle characteristics and performance. Preliminary estimates of the economic effects of the use of graphite composite materials on vehicle manufacturers and consumers are included. The combined impact on the national economy of vehicle design changes to meet mandated fuel efficiency requirements and the extensive use of graphite composite materials in the automotive industry is considered.

  5. Reversible Intercalation of Fluoride-Anion Receptor Complexes in Graphite

    NASA Technical Reports Server (NTRS)

    West, William C.; Whitacre, Jay F.; Leifer, Nicole; Greenbaum, Steve; Smart, Marshall; Bugga, Ratnakumar; Blanco, Mario; Narayanan, S. R.

    2007-01-01

    We have demonstrated a route to reversibly intercalate fluoride-anion receptor complexes in graphite via a nonaqueous electrochemical process. This approach may find application for a rechargeable lithium-fluoride dual-ion intercalating battery with high specific energy. The cell chemistry presented here uses graphite cathodes with LiF dissolved in a nonaqueous solvent through the aid of anion receptors. Cells have been demonstrated with reversible cathode specific capacity of approximately 80 mAh/g at discharge plateaus of upward of 4.8 V, with graphite staging of the intercalant observed via in situ synchrotron X-ray diffraction during charging. Electrochemical impedance spectroscopy and B-11 nuclear magnetic resonance studies suggest that cointercalation of the anion receptor with the fluoride occurs during charging, which likely limits the cathode specific capacity. The anion receptor type dictates the extent of graphite fluorination, and must be further optimized to realize high theoretical fluorination levels. To find these optimal anion receptors, we have designed an ab initio calculations-based scheme aimed at identifying receptors with favorable fluoride binding and release properties.

  6. Development of a portable graphite calorimeter for radiation dosimetry.

    PubMed

    Sakama, Makoto; Kanai, Tatsuaki; Fukumura, Akifumi

    2008-01-01

    We developed and performance-tested a portable graphite calorimeter designed to measure the absolute dosimetry of various beams including heavy-ion beams, based on a flexible and convenient means of measurement. This measurement system is fully remote-controlled by the GPIB system. This system uses a digital PID (Proportional, Integral, Derivative) control method based on the LabVIEW software. It was possible to attain stable conditions in a shorter time by this system. The standard deviation of the measurements using the calorimeter was 0.79% at a dose rate of 0.8 Gy/min in 17 calorimeter runs for a (60)Co photon beam. The overall uncertainties for the absorbed dose to graphite and water of the (60)Co photon beam using the developed calorimeter were 0.89% and 1.35%, respectively. Estimations of the correction factors due to vacuum gaps, impurities in the core, the dose gradient and the radiation profile were included in the uncertainties. The absorbed doses to graphite and water irradiated by the (60)Co photon beam were compared with dosimetry measurements obtained using three ionization chambers. The absorbed doses to graphite and water estimated by the two dosimetry methods agreed within 0.1% and 0.3%, respectively. PMID:21976250

  7. Recent buckling experiences with spiral wound flexible graphite filled gaskets

    SciTech Connect

    Mueller, R.T.

    1996-12-01

    Given the long and successful history of spiral wound asbestos filled gaskets as widely used in petrochemical plants and refineries, the evolution to flexible graphite filled spiral wound gaskets was expected to be relatively straightforward. For the most part, the transition to flexible graphite has occurred with relatively good success consistent with its improved sealing performance. However, recent experiences reported with buckling type instability problems of flexible graphite filled spiral wound gaskets warrants another look at the industry practices covering this type of gasket. The paper presents findings from 2 different but related instability problems involving spiral would flexible graphite filled gaskets. The first involved Class 1500 and 2500 spiral wound gaskets fitted with inner retaining rings which suffered severe inward buckling with initial boltup. The second experience pertains to Class 600 and lower gaskets supplied without inner retaining rings. Gaskets supplied in both cases complied fully with ASME B16.20 requirements, which highlights possible inadequacies in this standard for spiral wound gaskets. Efforts have been initiated to work with manufacturers in their assessment of fundamental design considerations and with appropriate Code committees to address apparent deficiencies discovered with the industry standards for this type of gasket.

  8. Sealing nuclear graphite with pyrolytic carbon

    NASA Astrophysics Data System (ADS)

    Feng, Shanglei; Xu, Li; Li, Li; Bai, Shuo; Yang, Xinmei; Zhou, Xingtai

    2013-10-01

    Pyrolytic carbon (PyC) coatings were deposited on IG-110 nuclear graphite by thermal decomposition of methane at ∼1830 °C. The PyC coatings are anisotropic and airtight enough to protect IG-110 nuclear graphite against the permeation of molten fluoride salts and the diffusion of gases. The investigations indicate that the sealing nuclear graphite with PyC coating is a promising method for its application in Molten Salt Reactor (MSR).

  9. Removal of carbon-14 from irradiated graphite

    NASA Astrophysics Data System (ADS)

    Dunzik-Gougar, Mary Lou; Smith, Tara E.

    2014-08-01

    Approximately 250,000 tonnes of irradiated graphite waste exists worldwide and that quantity is expected to increase with decommissioning of Generation II reactors and deployment of Generation IV gas-cooled, graphite moderated reactors. This situation indicates the need for a graphite waste management strategy. On of the isotopes of great concern for long-term disposal of irradiated graphite is carbon-14 (14C), with a half-life of 5730 years. Study of irradiated graphite from some nuclear reactors indicates 14C is concentrated on the outer 5 mm of the graphite structure. The aim of the research presented here is to develop a practical method by which 14C can be removed. In parallel with these efforts, the same irradiated graphite material is being characterized to identify the chemical form of 14C in irradiated graphite. A nuclear-grade graphite, NBG-18, and a high-surface-area graphite foam, POCOFoam®, were exposed to liquid nitrogen (to increase the quantity of 14C precursor) and neutron-irradiated (1013 neutrons/cm2/s). During post-irradiation thermal treatment, graphite samples were heated in the presence of an inert carrier gas (with or without the addition of an oxidant gas), which carries off gaseous products released during treatment. Graphite gasification occurs via interaction with adsorbed oxygen complexes. Experiments in argon only were performed at 900 °C and 1400 °C to evaluate the selective removal of 14C. Thermal treatment also was performed with the addition of 3 and 5 vol% oxygen at temperatures 700 °C and 1400 °C. Thermal treatment experiments were evaluated for the effective selective removal of 14C. Lower temperatures and oxygen levels correlated to more efficient 14C removal.

  10. Nanostructured carbon films with oriented graphitic planes

    SciTech Connect

    Teo, E. H. T.; Kalish, R.; Kulik, J.; Kauffmann, Y.; Lifshitz, Y.

    2011-03-21

    Nanostructured carbon films with oriented graphitic planes can be deposited by applying energetic carbon bombardment. The present work shows the possibility of structuring graphitic planes perpendicular to the substrate in following two distinct ways: (i) applying sufficiently large carbon energies for deposition at room temperature (E>10 keV), (ii) utilizing much lower energies for deposition at elevated substrate temperatures (T>200 deg. C). High resolution transmission electron microscopy is used to probe the graphitic planes. The alignment achieved at elevated temperatures does not depend on the deposition angle. The data provides insight into the mechanisms leading to the growth of oriented graphitic planes under different conditions.

  11. METHOD FOR COATING GRAPHITE WITH NIOBIUM CARBIDE

    DOEpatents

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

    1962-01-16

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

  12. Destruction of nuclear graphite using closed chamber incineration

    SciTech Connect

    Senor, D.J.; Hollenberg, G.W.; Morgan, W.C.; Marianowski, L.G.

    1994-03-01

    Closed chamber incineration (CCI) is a novel technique by which irradiated nuclear graphite may be destroyed without the risk of radioactive cation release into the environment. The process utilizes an enclosed combustion chamber coupled with molten carbonate fuel cells (MCFCs). The transport of cations is intrinsically suppressed by the MCFCs, such that only the combustion gases are conducted through for release to the environment. An example CCI design was developed which had as its goal the destruction of graphite fuel elements from the Fort St. Vrain reactor (FSVR). By employing CCI, the volume of high level waste from the FSVR will be reduced by approximately 87 percent. Additionally, the incineration process will convert the SiC coating on the FSVR fuel particles to SiO{sub 2}, thus creating a form potentially suitable for direct incorporation in a vitrification process stream. The design is compact, efficient, and makes use of currently available technology.

  13. A new ring-shaped graphite monitor ionization chamber

    NASA Astrophysics Data System (ADS)

    Yoshizumi, M. T.; Caldas, L. V. E.

    2010-07-01

    A ring-shaped monitor ionization chamber was developed at the Instituto de Pesquisas Energéticas e Nucleares. This ionization chamber presents an entrance window of aluminized polyester foil. The guard ring and collecting electrode are made of graphite coated Lucite plates. The main difference between this new ionization chamber and commercial monitor chambers is its ring-shaped design. The new monitor chamber has a central hole, allowing the passage of the direct radiation beam without attenuation; only the penumbra radiation is measured by the sensitive volume. This kind of ionization chamber design has already been tested, but using aluminium electrodes. By changing the electrode material from aluminium to a graphite coating, an improvement in the chamber response stability was expected. The pre-operational tests, as saturation curve, recombination loss and polarity effect showed satisfactory results. The repeatability and the long-term stability tests were also evaluated, showing good agreement with international recommendations.

  14. Gasifiable carbon-graphite fibers

    NASA Technical Reports Server (NTRS)

    Humphrey, Marshall F. (Inventor); Ramohalli, Kumar N. R. (Inventor); Dowler, Warren L. (Inventor)

    1982-01-01

    Fine, carbon-graphite fibers do not combust during the combustion of a composite and are expelled into the air as fine conductive particles. Coating of the fibers with a salt of a metal having a work function below 4.2 eV such as an alkaline earth metal salt, e.g., calcium acetate, catalytically enhances combustion of the fibers at temperatures below 1000.degree. C. such that the fibers self-support combustion and burn to produce a non-conductive ash. Fire-polishing the fibers before application of the coating is desirable to remove sizing to expose the carbon surface to the catalyst.

  15. Resin/graphite fiber composites

    NASA Technical Reports Server (NTRS)

    Cavano, P. J.; Jones, R. J.; Vaughan, R. W.

    1972-01-01

    High temperature resin matrices suitable for use in advanced graphite fiber composites for jet engine applications were evaluated. A series of planned, sequential screening experiments with resin systems in composite form were performed to reduce the number of candidates to a single A-type polyimide resin that repetitively produced void-free, high strength and modulus composites acceptable for use in the 550 F range for 1000 hours. An optimized processing procedure was established for this system. Extensive mechanical property studies characterized this single system, at room temperature, 500 F, 550 F and 600 F, for various exposure times.

  16. Estimation of partial pressure during graphite conditioning by matrix method

    NASA Astrophysics Data System (ADS)

    Chaudhuri, P.; Prakash, A.; Reddy, D. C.

    2008-05-01

    Plasma Facing Components (PFC) of SST-1 tokamak are designed to be compatible for UHV as it is kept in the main vacuum vessel. Graphite is the most widely used plasma facing material in present day tokamaks. High thermal shock resistance and low atomic number carbon are the most important properties of graphite for this application. However, graphite is porous and absorbs gases, which may be released during plasma operation. Graphite tiles are baked at high temperature of about 1000 °C in high vacuum (10-5 Torr) for several hours before installing them in the tokamak to remove the impurities (mainly water vapour and metal impurities), which may have been deposited during machining of the tiles‥ The measurements of the released gas (such as H2, H2O, CO, CO2, Hydrocarbons, etc.) from graphite tiles during baking are accomplished with the help of a Quadrupole Mass Analyzer (QMA). Since, the output of this measurement is a mass spectrum and not the partial pressures of the residual gases, one needs to adopt some procedure to convert the spectrum to obtain the partial pressures. The conventional method of analysis is tedious and time consuming. We propose a new approach based on constructing a set of linear equations and solving them using matrix operations. This is a simple method compared to the conventional one and also eliminates the limitations of the conventional method. A Fortran program has been developed which identifies the likely gases present in the vacuum system and calculates their partial pressures from the data of the residual gas analyzers. Application of this method of calculating partial pressures from mass spectra data will be discussed in detail in this paper.

  17. Graphitized-carbon fiber/carbon char fuel

    SciTech Connect

    Cooper, John F.

    2007-08-28

    A method for recovery of intact graphitic fibers from fiber/polymer composites is described. The method comprises first pyrolyzing the graphite fiber/polymer composite mixture and then separating the graphite fibers by molten salt electrochemical oxidation.

  18. Evaluation of long-duration exposure to the natural space environment on graphite-polyimide and graphite-epoxy mechanical properties (A0175)

    NASA Technical Reports Server (NTRS)

    Powell, J. H.; Welch, D. W.

    1984-01-01

    The primary objective of this experiment is to accumulate the needed operational data associated with the exposure of graphite-polyimide and graphite-epoxy material to the environments of space. The experiment will be mounted in two 3-in.-deep peripheral trays. Graphite-polyimide specimens will occupy 1 1/3 trays and the graphite-epoxy specimens will occupy two-thirds of a tray. The experiment approach requires two matched sets of specimens with traceable records that are maintained for materials processing and specimen quality. After fabrication, one set of each test specimen will be sectioned and structurally tested to serve as a data baseline. After the flight, the other set of specimens will undergo extensive measurements of mechanical properties for comparison with the original data baseline. Structural testing of the graphite-polyimide specimens will provide strength and elastic data in tension, compression, and shear. Transverse tension microcracking and crack propagation will be evaluated by photomicroscopy. Structural testing of the graphite-epoxy specimens will include verification of laminate, core, adhesive, and fatigue properties as applied to the design and analysis of the payload bay door. Microcracking and crack propagation will also be analyzed by photomicroscopy.

  19. The action of macrosounds on graphite ore and derived products

    NASA Technical Reports Server (NTRS)

    Bradeteanu, C.; Dragan, O.

    1974-01-01

    A suspension of graphite ore, floated graphite, and the gangue left over from flotation were subjected to the action of macrosounds under determinant conditions. The following was found: (1) The graphite ore undergoes an efficient settling action. (2) The floated graphite is strongly crushed down to the dimensions of colloidal graphite. (3) The gangue left over from flotation can be further processed to recuperate graphite from its nuclei.

  20. Hydrogen storage in graphite nanofibers

    SciTech Connect

    Park, C.; Tan, C.D.; Hidalgo, R.; Baker, R.T.K.; Rodriguez, N.M.

    1998-08-01

    Graphite nanofibers (GNF) are a type of material that is produced by the decomposition of carbon containing gases over metal catalyst particles at temperatures around 600 C. These molecularly engineered structures consist of graphene sheets perfectly arranged in a parallel, perpendicular or at angle orientation with respect to the fiber axis. The most important feature of the material is that only edges are exposed. Such an arrangement imparts the material with unique properties for gas adsorption because the evenly separated layers constitute the most ordered set of nanopores that can accommodate an adsorbate in the most efficient manner. In addition, the non-rigid pore walls can also expand so as to accommodate hydrogen in a multilayer conformation. Of the many varieties of structures that can be produced the authors have discovered that when gram quantities of a selected number of GNF are exposed to hydrogen at pressures of {approximately} 2,000 psi, they are capable of adsorbing and storing up to 40 wt% of hydrogen. It is believed that a strong interaction is established between hydrogen and the delocalized p-electrons present in the graphite layers and therefore a new type of chemistry is occurring within these confined structures.

  1. Development of polyphenylquinoxaline graphite composites

    NASA Technical Reports Server (NTRS)

    Hoggatt, J. T.; Hill, S. G.; Shdo, J. G.

    1974-01-01

    This exploratory program was divided into four basic tasks. The initial phase was devoted toward investigating processing variables associated with previously developed PPO resins. These polymers were derived from p-bis(phenyl glyoxalyl)benzene reacted with 3,3'-diamino benzidine and/or 3,3',4,4'-tetramino benzophenone. Four new phenyl quinoxaline polymers were synthesized and characterized in Tasks 2 and 3. These consisted of a hydroxyl group containing PPQ synthesized from 3,3'-diamino benzidine (DAB), m-bis(phenyl glyoxal)benzene and m-bis(p'-hydroxy phenyl glyoxalyl) benzene; a cyano group containing PPQ from the reaction of DAB and p-bis(p'-cyano phenoxy phenyl glyoxalyl)benzene; an end-capped block copolymer; and a polymer from the reaction of 3,3',4,4'-tetraamino benzo phenone and m-bis(phenyl glyoxalyl)benzene. The latter two polymers were chosen for composite studies in the latter two tasks of the program. Mechanical properties of the graphite reinforced PPQ composites were determined over the temperature range of +21 C to 316 C. Flexural strengths of the HMS graphite fiber composites were in excess of 8.97 X 10 to the 8th power N/sq m (130,000 psi) at +21 C (70 F) with over 50% strength retention at +316 C.

  2. SIMPLIFIED SODIUM GRAPHITE REACTOR SYSTEM

    DOEpatents

    Dickinson, R.W.

    1963-03-01

    This patent relates to a nuclear power reactor comprising a reactor vessel, shielding means positioned at the top of said vessel, means sealing said reactor vessel to said shielding means, said vessel containing a quantity of sodium, a core tank, unclad graphite moderator disposed in said tank, means including a plurality of process tubes traversing said tank for isolating said graphite from said sodium, fuel elements positioned in said process tubes, said core tank being supported in spaced relation to the walls and bottom of said reactor vessel and below the level of said sodium, neutron shielding means positioned adjacent said core tank between said core tank and the walls of said vessel, said neutron shielding means defining an annuiar volume adjacent the inside wall of said reactor vessel, inlet plenum means below said core tank for providing a passage between said annular volume and said process tubes, heat exchanger means removably supported from the first-named shielding means and positioned in said annular volume, and means for circulating said sodium over said neutron shielding means down through said heat exchanger, across said inlet plenum and upward through said process tubes, said last-named means including electromagnetic pumps located outside said vessel and supported on said vessel wall between said heat exchanger means and said inlet plenum means. (AEC)

  3. Mineral Resource of the Month: Graphite

    USGS Publications Warehouse

    Olson, Donald W.

    2008-01-01

    Graphite, a grayish black opaque mineral with a metallic luster, is one of four forms of pure crystalline carbon (the others are carbon nanotubes, diamonds and fullerenes). It is one of the softest minerals and it exhibits perfect basal (one-plane) cleavage. Graphite is the most electrically and thermally conductive of the nonmetals, and it is chemically inert.

  4. Chemical Sputtering Studies of Lithiated Graphite

    NASA Astrophysics Data System (ADS)

    Raman, Priya; Groll, Andrew; Abrams, Tyler; Curreli, Davide; Andruczyk, Daniel; Ruzic, D. N.

    2012-10-01

    Lithium treatments in the National Spherical Torus Experiment have shown dramatic improvements in plasma performance. In order to understand the complex system of lithiated ATJ graphite, chemical sputtering measurements of plain and lithiated ATJ graphite are conducted in IIAX (Ion Surface Interaction Experiment) facility with a differentially pumped Magnetic Sector Residual Gas Analyzer (MSRGA). The ATJ graphite target is mounted in such way that the target can be translated along a line to different positions to get direct comparison of ATJ and lithiated ATJ. Target is heated using joule heating and is connected to a biasing circuitry. Chemical sputtering of graphite is dependent on the ion energy and substrate temperature, hence the total effects of treating ATJ graphite with lithium in hydrogen plasma is investigated in terms of different target temperatures and bias voltages. For this purpose, lithium is evaporated in-situ onto ATJ graphite and chemically sputtered species in hydrogen plasma is measured using MSRGA. The dominant chemical sputtering product is CH4. It was found that lithium treatments have suppressed the chemical sputtering of ATJ Graphite. The suppression of chemical sputtering effect is presented as a function of varying lithium thickness on ATJ Graphite.

  5. Tire containing thermally exfoliated graphite oxide

    NASA Technical Reports Server (NTRS)

    Prud'homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor)

    2011-01-01

    A tire, tire lining or inner tube, containing a polymer composite, made of at least one rubber and/or at least one elastomer and a modified graphite oxide material, which is a thermally exfoliated graphite oxide with a surface area of from about 300 sq m/g to 2600 sq m/g.

  6. Developments in Hollow Graphite Fiber Technology

    NASA Technical Reports Server (NTRS)

    Stallcup, Michael; Brantley, Lott W., Jr. (Technical Monitor)

    2002-01-01

    Hollow graphite fibers will be lighter than standard solid graphite fibers and, thus, will save weight in optical components. This program will optimize the processing and properties of hollow carbon fibers developed by MER and to scale-up the processing to produce sufficient fiber for fabricating a large ultra-lightweight mirror for delivery to NASA.

  7. The effect of neutron irradiation damage on the properties of grade NBG-10 graphite

    NASA Astrophysics Data System (ADS)

    Burchell, Timothy D.; Snead, Lance L.

    2007-09-01

    Nuclear block graphite-10 (NBG-10) is a medium-grain, near-isotropic graphite manufactured by SGL Carbon Company at their plant in Chedde, France. NBG-10 graphite was developed as a candidate core structural material for the pebble bed modular reactor (PBMR) currently being designed in South Africa, and for prismatic reactor concepts being developed in the USA and Europe. NBG-10 is one of several graphites included in the US-DOE Very High Temperature Reactor (VHTR) program. Thirty-six NBG-10 graphite flexure bars have been successfully irradiated in a series of 18 HFIR PTT capsules at ORNL. The capsule irradiation temperatures were 294 ± 25, 360 ± 25 and 691 ± 25 °C. The peak doses attained were 4.93, 6.67, and 6.69 × 10 25 n/m 2 [ E > 0.1 MeV] at ˜294, ˜360, and ˜691 °C, respectively. The high temperature irradiation volume and dimensional change behavior, and flexure strength and elastic modulus changes of NBG-10 were similar to other extruded, near-isotropic grades, such as H-451, which has been irradiated previously at ORNL. The low temperature (˜294 °C) irradiation volume and dimensional change behavior was also as expected for extruded graphites, i.e., exhibiting low dose swelling prior to shrinkage. This behavior was attributed to the relaxation of internal stress arising from the graphite manufacturing process and specimen machining. While the data reported here do not represent a complete database for NBG-10 graphite, they give a measure of confidence that the current generation of nuclear graphites will behave in a familiar and well understood manner.

  8. Microstructural Characterization of Next Generation Nuclear Graphites

    SciTech Connect

    Karthik Chinnathambi; Joshua Kane; Darryl P. Butt; William E. Windes; Rick Ubic

    2012-04-01

    This article reports the microstructural characteristics of various petroleum and pitch based nuclear graphites (IG-110, NBG-18, and PCEA) that are of interest to the next generation nuclear plant program. Bright-field transmission electron microscopy imaging was used to identify and understand the different features constituting the microstructure of nuclear graphite such as the filler particles, microcracks, binder phase, rosette-shaped quinoline insoluble (QI) particles, chaotic structures, and turbostratic graphite phase. The dimensions of microcracks were found to vary from a few nanometers to tens of microns. Furthermore, the microcracks were found to be filled with amorphous carbon of unknown origin. The pitch coke based graphite (NBG-18) was found to contain higher concentration of binder phase constituting QI particles as well as chaotic structures. The turbostratic graphite, present in all of the grades, was identified through their elliptical diffraction patterns. The difference in the microstructure has been analyzed in view of their processing conditions.

  9. Research on graphite reinforced glass matrix composites

    NASA Technical Reports Server (NTRS)

    Bacon, J. F.; Prewo, K. M.; Thompson, E. R.

    1978-01-01

    A composite that can be used at temperatures up to 875 K with mechanical properties equal or superior to graphite fiber reinforced epoxy composites is presented. The composite system consist of graphite fiber, uniaxially or biaxially, reinforced borosilicate glass. The mechanical and thermal properties of such a graphite fiber reinforced glass composite are described, and the system is shown to offer promise as a high performance structural material. Specific properties that were measured were: a modified borosilicate glass uniaxially reinforced by Hercules HMS graphite fiber has a three-point flexural strength of 1030 MPa, a four-point flexural strength of 964 MPa, an elastic modulus of 199 GPa and a failure strain of 0.0052. The preparation and properties of similar composites with Hercules HTS, Celanese DG-102, Thornel 300 and Thornel Pitch graphite fibers are also described.

  10. Significance of primary irradiation creep in graphite

    NASA Astrophysics Data System (ADS)

    Erasmus, Christiaan; Kok, Schalk; Hindley, Michael P.

    2013-05-01

    Traditionally primary irradiation creep is introduced into graphite analysis by applying the appropriate amount of creep strain to the model at the initial time-step. This is valid for graphite components that are subjected to high fast neutron flux fields and constant stress fields, but it does not allow for the effect of movement of stress locations around a graphite component during life, nor does it allow primary creep to be applied rate-dependently to graphite components subject to lower fast neutron flux. This paper shows that a differential form of primary irradiation creep in graphite combined with the secondary creep formulation proposed by Kennedy et al. performs well when predicting creep behaviour in experimental samples. The significance of primary irradiation creep in particular in regions with lower flux is investigated. It is shown that in low flux regions with a realistic operating lifetime primary irradiation creep is significant and is larger than secondary irradiation creep.

  11. Modeling Fission Product Sorption in Graphite Structures

    SciTech Connect

    Szlufarska, Izabela; Morgan, Dane; Allen, Todd

    2013-04-08

    The goal of this project is to determine changes in adsorption and desorption of fission products to/from nuclear-grade graphite in response to a changing chemical environment. First, the project team will employ principle calculations and thermodynamic analysis to predict stability of fission products on graphite in the presence of structural defects commonly observed in very high- temperature reactor (VHTR) graphites. Desorption rates will be determined as a function of partial pressure of oxygen and iodine, relative humidity, and temperature. They will then carry out experimental characterization to determine the statistical distribution of structural features. This structural information will yield distributions of binding sites to be used as an input for a sorption model. Sorption isotherms calculated under this project will contribute to understanding of the physical bases of the source terms that are used in higher-level codes that model fission product transport and retention in graphite. The project will include the following tasks: Perform structural characterization of the VHTR graphite to determine crystallographic phases, defect structures and their distribution, volume fraction of coke, and amount of sp2 versus sp3 bonding. This information will be used as guidance for ab initio modeling and as input for sorptivity models; Perform ab initio calculations of binding energies to determine stability of fission products on the different sorption sites present in nuclear graphite microstructures. The project will use density functional theory (DFT) methods to calculate binding energies in vacuum and in oxidizing environments. The team will also calculate stability of iodine complexes with fission products on graphite sorption sites; Model graphite sorption isotherms to quantify concentration of fission products in graphite. The binding energies will be combined with a Langmuir isotherm statistical model to predict the sorbed concentration of fission

  12. Synthesis of Diamond Nanoplatelets/Carbon Nanowalls on Graphite Substrate by MPCVD

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Lyu, Jilei; Lin, Xiaoqi; Zhu, Jinfeng; Man, Weidong; Jiang, Nan

    2015-07-01

    The films composed of carbon nanowalls and diamond nanoplatelets, respectively, can be simultaneously formed on graphite substrate by controlling the hydrogen etching rate during microwave plasma chemical vapor deposition. To modulate the etching rate, two kinds of substrate design were used: a bare graphite plate and a graphite groove covered with a single crystal diamond sheet. After deposition at 1200°C for 3 hours, we find that dense diamond nanoplatelets were grown on the bare graphite, whereas carbon nanowalls were formed on the grooved surface, indicating that not only reaction temperature but also etching behavior is a key factor for nanostructure formation. supported by the Public Welfare Technology Application Projects of Zhejiang Province, China (No. 2013C33G3220012)

  13. Detection of graphite balls for the fuel handling system in HTGR using eddy current testing

    NASA Astrophysics Data System (ADS)

    Dong, Li; ZhenGuo, Sun; Qiang, Chen

    2010-06-01

    The spherical graphite fuel elements (graphite balls) are transported into and out of the core in high-temperature gas-cooled pebble bed reactors (HTGR) by a fuel handling system (FHS) during plant operation. In order to control the reactor, it is necessary to have information on the location and movement of the graphite balls at various points of the FHS. In this paper, a new through-transmission eddy current testing probe has been put forward to detect the graphite balls. The probe's electromagnetic finite element model (FEM) has been established so as to study the factors affecting the performance of the probe. On this basis, electromagnetic detection parameters and probe designs have been optimised. According to the results of analysis, a bidirectional detector for the fuel ball handling system of HTGR has been developed. The experimental results confirm the validity of the FEM, and show that the detector works accurately and reliably, which meets the requirements of application in HTGR.

  14. Next Generation Nuclear Plant Phenomena Identification and Ranking Tables (PIRTs) Volume 5: Graphite PIRTs

    SciTech Connect

    Burchell, Timothy D; Bratton, Rob; Marsden, Barry; Srinivasan, Makuteswara; Penfield, Scott; Mitchell, Mark; Windes, Will

    2008-03-01

    Here we report the outcome of the application of the Nuclear Regulatory Commission (NRC) Phenomena Identification and Ranking Table (PIRT) process to the issue of nuclear-grade graphite for the moderator and structural components of a next generation nuclear plant (NGNP), considering both routine (normal operation) and postulated accident conditions for the NGNP. The NGNP is assumed to be a modular high-temperature gas-cooled reactor (HTGR), either a gas-turbine modular helium reactor (GTMHR) version [a prismatic-core modular reactor (PMR)] or a pebble-bed modular reactor (PBMR) version [a pebble bed reactor (PBR)] design, with either a direct- or indirect-cycle gas turbine (Brayton cycle) system for electric power production, and an indirect-cycle component for hydrogen production. NGNP design options with a high-pressure steam generator (Rankine cycle) in the primary loop are not considered in this PIRT. This graphite PIRT was conducted in parallel with four other NRC PIRT activities, taking advantage of the relationships and overlaps in subject matter. The graphite PIRT panel identified numerous phenomena, five of which were ranked high importance-low knowledge. A further nine were ranked with high importance and medium knowledge rank. Two phenomena were ranked with medium importance and low knowledge, and a further 14 were ranked medium importance and medium knowledge rank. The last 12 phenomena were ranked with low importance and high knowledge rank (or similar combinations suggesting they have low priority). The ranking/scoring rationale for the reported graphite phenomena is discussed. Much has been learned about the behavior of graphite in reactor environments in the 60-plus years since the first graphite rectors went into service. The extensive list of references in the Bibliography is plainly testament to this fact. Our current knowledge base is well developed. Although data are lacking for the specific grades being considered for Generation IV (Gen IV

  15. Evaluation of co-cokes from bituminous coal with vacuum resid or decant oil, and evaluation of anthracites, as precursors to graphite

    NASA Astrophysics Data System (ADS)

    Nyathi, Mhlwazi S.

    2011-12-01

    Graphite is utilized as a neutron moderator and structural component in some nuclear reactor designs. During the reactor operaction the structure of graphite is damaged by collision with fast neutrons. Graphite's resistance to this damage determines its lifetime in the reactor. On neutron irradiation, isotropic or near-isotropic graphite experiences less structural damage than anisotropic graphite. The degree of anisotropy in a graphite artifact is dependent on the structure of its precursor coke. Currently, there exist concerns over a short supply of traditional precursor coke, primarily due to a steadily increasing price of petroleum. The main goal of this study was to study the anisotropic and isotropic properties of graphitized co-cokes and anthracites as a way of investigating the possibility of synthesizing isotropic or near-isotropic graphite from co-cokes and anthracites. Demonstrating the ability to form isotropic or near-isotropic graphite would mean that co-cokes and anthracites have a potential use as filler material in the synthesis of nuclear graphite. The approach used to control the co-coke structure was to vary the reaction conditions. Co-cokes were produced by coking 4:1 blends of vacuum resid/coal and decant oil/coal at temperatures of 465 and 500 °C for reaction times of 12 and 18 hours under autogenous pressure. Co-cokes obtained were calcined at 1420 °C and graphitized at 3000 °C for 24 hours. Optical microscopy, X-ray diffraction, temperature-programmed oxidation and Raman spectroscopy were used to characterize the products. It was found that higher reaction temperature (500 °C) or shorter reaction time (12 hours) leads to an increase in co-coke structural disorder and an increase in the amount of mosaic carbon at the expense of textural components that are necessary for the formation of anisotropic structure, namely, domains and flow domains. Characterization of graphitized co-cokes showed that the quality, as expressed by the degree of

  16. Supercapacitors with graphene oxide separators and reduced graphite oxide electrodes

    NASA Astrophysics Data System (ADS)

    Shulga, Y. M.; Baskakov, S. A.; Baskakova, Y. V.; Volfkovich, Y. M.; Shulga, N. Y.; Skryleva, E. A.; Parkhomenko, Y. N.; Belay, K. G.; Gutsev, G. L.; Rychagov, A. Y.; Sosenkin, V. E.; Kovalev, I. D.

    2015-04-01

    A supercapacitor (SC) with electrodes fabricated from graphite oxide reduced by a microwave exfoliation (MEGO) method and the separator made from the graphite oxide paper (GOP) formed after precipitation of water suspension of graphene oxide was designed for the first time. The specific capacitance of this SC exceeded 200 F/g. The specific area of our MEGO is 2400 m2/g when measured using the standard contact porosimetry method, whereas it is several times smaller (∼600 m2/g) when measured by using the Brunauer-Emmett-Teller method based on the low-temperature nitrogen adsorption. By using the angle resolved X-ray photoelectron spectroscopy we found that surface layers of the GOP separator contain smaller oxygen concentration than the bulk layers.

  17. Heptagraphene: Tunable Dirac Cones in a Graphitic Structure.

    PubMed

    Lopez-Bezanilla, Alejandro; Martin, Ivar; Littlewood, Peter B

    2016-01-01

    We predict the existence and dynamical stability of heptagraphene, a new graphitic structure formed of rings of 10 carbon atoms bridged by carbene groups yielding seven-membered rings. Despite the rectangular unit cell, the band structure is topologically equivalent to that of strongly distorted graphene. Density-functional-theory calculations demonstrate that heptagraphene has Dirac cones on symmetry lines that are robust against biaxial strain but which open a gap under shear. At high deformation values bond reconstructions lead to different electronic band arrangements in dynamically stable configurations. Within a tight-binding framework this richness of the electronic behavior is identified as a direct consequence of the symmetry breaking within the cell which, unlike other graphitic structures, leads to band gap opening. A combined approach of chemical and physical modification of graphene unit cell unfurls the opportunity to design carbon-based systems in which one aims to tune an electronic band gap. PMID:27622775

  18. Aging behavior and life prediction of graphite composites

    NASA Technical Reports Server (NTRS)

    Ramohalli, Kumar; Raasch, David

    1989-01-01

    This paper presents experimental data from two independent tests, designed to determine the long-term reliability of composite materials. The technique of accelerated aging at elevated temperatures is employed. In the first set, graphite fiber, epoxy composites in five ply layups are manufactured and tested in the standard short-beam shear mode. In the second set, Nomex honeycomb, graphite fiber/epoxy composite face and rear sheet sandwich coupons are tested. After satisfying simple consistency checks, data interpretation is attempted within the framework of an Arrhenius degradation model. The elevated temperature is assumed to influence the degradation according to this temperature-dependent rate law. From these tests on five-ply composites and honeycomb sandwiches, it is concluded that aging is not a serious problem.

  19. Superconductivity in graphite intercalation compounds

    SciTech Connect

    Smith, Robert P.; Weller, Thomas E.; Howard, Christopher A.; Dean, Mark P. M.; Rahnejat, Kaveh C.; Saxena, Siddharth S.; Ellerby, Mark

    2015-02-26

    This study examines the field of superconductivity in the class of materials known as graphite intercalation compounds which has a history dating back to the 1960s. This paper recontextualizes the field in light of the discovery of superconductivity in CaC₆ and YbC₆ in 2005. In what follows, we outline the crystal structure and electronic structure of these and related compounds. We go on to experiments addressing the superconducting energy gap, lattice dynamics, pressure dependence, and how this relates to theoretical studies. The bulk of the evidence strongly supports a BCS superconducting state. However, important questions remain regarding which electronic states and phonon modes are most important for superconductivity and whether current theoretical techniques can fully describe the dependence of the superconducting transition temperature on pressure and chemical composition.

  20. Superconductivity in graphite intercalation compounds

    DOE PAGESBeta

    Smith, Robert P.; Weller, Thomas E.; Howard, Christopher A.; Dean, Mark P. M.; Rahnejat, Kaveh C.; Saxena, Siddharth S.; Ellerby, Mark

    2015-02-26

    This study examines the field of superconductivity in the class of materials known as graphite intercalation compounds which has a history dating back to the 1960s. This paper recontextualizes the field in light of the discovery of superconductivity in CaC₆ and YbC₆ in 2005. In what follows, we outline the crystal structure and electronic structure of these and related compounds. We go on to experiments addressing the superconducting energy gap, lattice dynamics, pressure dependence, and how this relates to theoretical studies. The bulk of the evidence strongly supports a BCS superconducting state. However, important questions remain regarding which electronic statesmore » and phonon modes are most important for superconductivity and whether current theoretical techniques can fully describe the dependence of the superconducting transition temperature on pressure and chemical composition.« less

  1. Retention of hydrogen in graphite

    SciTech Connect

    Langley, R.A.

    1986-10-01

    The retention of hydrogen in POCO AXF-5Q graphite has been measured at room temperature as a function of fluence and flux for H/sub 2//sup +/ ions at energies from 250 to 500 eV provided by a glow discharge. More than 2 x 10/sup 18/ H/cm/sup 2/ has been retained, and no indication of saturation has been observed to a fluence of 5 x 10/sup 19/ H/cm/sup 2/. In this experiment, retention was found to increase linearly with fluence for constant flux. A flux dependence was observed; that is, the retention rate was observed to decrease monotonically as the flux increased. A change-over experiment, deuterium to hydrogen, was conducted; the results show that significant change-over occurs (i.e., about 30% change-over for a fluence of 5 x 10/sup 17/ D/cm/sup 2/).

  2. Resin/graphite fiber composites

    NASA Technical Reports Server (NTRS)

    Cavano, P. J.

    1974-01-01

    Processing techniques were developed for the fabrication of both polyphenylquinoxaline and polyimide composites by the in situ polymerization of monomeric reactants directly on the graphite reinforcing fibers, rather than using previously prepared prepolymer varnishes. Void-free polyphenylquinoxaline composites were fabricated and evaluated for room and elevated flexure and shear properties. The technology of the polyimide system was advanced to the point where the material is ready for commercial exploitation. A reproducible processing cycle free of operator judgment factors was developed for fabrication of void-free composites exhibiting excellent mechanical properties and a long time isothermal life in the range of 288 C to 316 C. The effects of monomer reactant stoichiometry and process modification on resin flow were investigated. Demonstration of the utility and quality of this polyimide system was provided through the successful fabrication and evaluation of four complex high tip speed fan blades.

  3. Development of polyphenylquinoxaline graphite composites

    NASA Technical Reports Server (NTRS)

    Shdo, J. D.

    1976-01-01

    Six polyphenylquinoxalines (PPQ) containing pendant cyano (CN) groups were synthesized. The polymers were characterized in terms of inherent viscosity, glass transition temperature, softening temperature and weight loss due to aging in air at 316 C (600 F). The potential for crosslinking PPQs by trimerization of pendant CN groups was investigated. A polymer derived from 1 mole 3,3,4,4 -tetraaminobenzophenone, .2 mole p-bis(p -cyanophenoxyphenylglyoxalyl)benzene and .8 mole p-bis(phenylglyoxalyl)benzene was selected for more extensive characterization in HM-S graphite fiber-reinforced composites. Mechanical properties were determined using composites made from HM-S fiber and polymer and composites made from HM-S fiber, polymer and a potential CN group trimerization catalyst. Composite mechanical properties, inter-laminar shear strength and flexure properties, were determined over the temperature range of +21 C to 316 C.

  4. Graphite Composite Booms with Integral Hinges

    NASA Technical Reports Server (NTRS)

    Alexander, Wes; Carlos, Rene; Rossoni, Peter; Sturm, James

    2006-01-01

    A document discusses lightweight instrument booms under development for use aboard spacecraft. A boom of this type comprises a thin-walled graphite fiber/ matrix composite tube with an integral hinge that can be bent for stowage and later allowed to spring back to straighten the boom for deployment in outer space. The boom design takes advantage of both the stiffness of the composite in tubular geometry and the flexibility of thin sections of the composite. The hinge is formed by machining windows in the tube at diametrically opposite locations so that there remain two opposing cylindrical strips resembling measuring tapes. Essential to the design is a proprietary composite layup that renders the hinge tough yet flexible enough to be bendable as much as 90 in either of two opposite directions. When the boom is released for deployment, the torque exerted by the bent hinge suffices to overcome parasitic resistance from harnesses and other equipment, so that the two sections of the hinge snap to a straight, rigid condition in the same manner as that of measuring tapes. Issues addressed in development thus far include selection of materials, out-of-plane bending, edge cracking, and separation of plies.

  5. Parametric study of graphite foam fins and application in heat exchangers

    NASA Astrophysics Data System (ADS)

    Collins, Michael

    This thesis focuses on the simulation and experimental studies of finned graphite foam extended surfaces to test their heat transfer characteristics and potential applications in condensers. Different fin designs were developed to conduct a parametric study on the thermal effectiveness with respect to thickness, spacing and fin offset angle. Each fin design was computationally simulated to estimate the heat transfer under specific conditions. The simulations showed that this optimal fin configuration could conduct more than 297% the amount of thermal energy as compared to straight aluminum fins. Graphite foam fins were then implemented into a simulation of the condenser system. The condenser was simulated with six different orientations of baffles to examine the incoming vapor and resulting two-phase flow patterns. The simulations showed that using both horizontal and vertical baffling provided the configuration with the highest heat transfer and minimized the bypass regions where the vapor would circumvent the graphite foam. This baffle configuration increased the amount of vapor flow through the inner graphite fins and cold water pipes, which gave this configuration the highest heat transfer. The results from experimental tests using the condenser system confirmed that using three baffles will increase performance consistent with the simulation results. The experimental data showed that the condenser using graphite foam had five times the heat transfer compared to the condenser using only aluminum fins. Incorporating baffles into the condenser using graphite foam enabled this system to conduct nearly ten times more heat transfer than the condenser system which only had aluminum fins without baffles. The results from this research indicate that graphite foam is a far superior material heat transfer enhancement material for heat transfer compared to aluminum used as an extended surface. The longitudinal and horizontal baffles incorporated into the condenser system

  6. Statistical Comparison of the Baseline Mechanical Properties of NBG-18 and PCEA Graphite

    SciTech Connect

    Mark C. Carroll; David T. Rohrbaugh

    2013-08-01

    High-purity graphite is the core structural material of choice in the Very High Temperature Reactor (VHTR), a graphite-moderated, helium-cooled design that is capable of producing process heat for power generation and for industrial process that require temperatures higher than the outlet temperatures of present nuclear reactors. The Baseline Graphite Characterization Program is endeavoring to minimize the conservative estimates of as-manufactured mechanical and physical properties by providing comprehensive data that captures the level of variation in measured values. In addition to providing a comprehensive comparison between these values in different nuclear grades, the program is also carefully tracking individual specimen source, position, and orientation information in order to provide comparisons and variations between different lots, different billets, and different positions from within a single billet. This report is a preliminary comparison between the two grades of graphite that were initially favored in the two main VHTR designs. NBG-18, a medium-grain pitch coke graphite from SGL formed via vibration molding, was the favored structural material in the pebble-bed configuration, while PCEA, a smaller grain, petroleum coke, extruded graphite from GrafTech was favored for the prismatic configuration. An analysis of the comparison between these two grades will include not only the differences in fundamental and statistically-significant individual strength levels, but also the differences in variability in properties within each of the grades that will ultimately provide the basis for the prediction of in-service performance. The comparative performance of the different types of nuclear grade graphites will continue to evolve as thousands more specimens are fully characterized from the numerous grades of graphite being evaluated.

  7. The characterization of fluorinated graphite

    SciTech Connect

    Hagaman, E.W.; Gakh, A.A.; Annis, B.K.

    1995-12-31

    The characterization of solid fossil fuels by chemical and spectroscopic methods requires extensive modelling in less complex systems for chemical proof of principle and technique development. In previous work coal was fluorinated with dilute, elemental fluorine under conditions that were expected to lead to materials that contain only fluoromethine moieties. The solid state, cross polarization/magic angle spinning (CP/MAS) {sup 13}C NMR spectra of the fluorinated coal are complex, indicating more chemical modification than originally anticipated. Our goal in the coal derivatization was to sequentially increase the severity of the fluorination and observe by {sup 19}F and {sup 13}C NMR the type and concentration of fluorine functional groups created in the coal milieu. This requires the ability to discriminate between C, CF, CF{sub 2}, and CF, moieties in the coal matrix. The task can be accomplished by implementing the spectral editing technique of Wu and Zilm which distinguishes different kinds of carbon resonances, especially CH and CH{sub 2} resonances. These experiments utilize cross polarization (CP) and polarization inversion (PI) to effect the discrimination. Our version of this experiment is a triple resonance experiment that incorporates {sup 19}F-{sup 13}C CP, PI, and simultaneous {sup 1}H and {sup 19}F dipolar decoupling. In order to evaluate the elemental fluorine chemistry in a matrix simpler than coal, fluorinated graphite was prepared. X-ray photoelectron spectroscopy (XPS) was used to characterize the surface species, i.e., count CF, CF{sub 2} and CF{sub 3} species. These well-characterized samples are the models we will use to test the NIVIR editing experiments. The XPS and atomic force microscopy (AFM) data on the first fluorinated graphites we have prepared are reported in this paper.

  8. Graphitized carbons for solid-phase extraction.

    PubMed

    Hennion, M C

    2000-07-14

    The objective of this review is to provide updated information about the most important features of graphitized carbonaceous sorbents used for solid-phase extraction (SPE) of organic compounds from liquid natural matrices or extracts. The surface characteristics of graphitized carbon blacks and porous graphitic carbons are described which are responsible for the various types interactions (hydrophobic, electronic and ion-exchange) with analytes. The method development is given which is based on the prediction from liquid chromatographic retention data obtained using porous graphitic carbon. Emphasis is placed on their capability for trapping very polar and water-soluble analytes from aqueous samples. Comparison is made between carbon-based SPE sorbents and other reversed-phase materials such as octadecyl silicas and highly cross-linked copolymers. Especially, the difficulty encountered for the desorption of some strongly retained analytes is explained by LC data and solutions are given for optimizing the composition and volume of the desorption solution. Many examples illustrate the various common features of graphitized carbons which are the extraction of very polar analytes and multiresidue extractions. Some applications are specific to graphitized carbon black due to the presence of surface functional groups. They include the extraction of anionic compounds such as benzene and naphthalene sulfonates or acidic pesticides. Other applications are specific to porous graphitic carbon due to its flat and homogeneous surface. One example is the trace extraction of coplanar polychlorinated biphenyls (PCBs), dibenzo-p-dioxins and dibenzofurans from other PCB congeners. PMID:10941668

  9. Effect of covalently bonded polysiloxane multilayers on the electrochemical behavior of graphite electrode in lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Pan, Qinmin; Jiang, Yinghua

    Polysiloxane multilayers were covalently bonded to the surface of natural graphite particles via diazonium chemistry and silylation reaction. The as-prepared graphite exhibited excellent discharge-charge behavior as negative electrode materials in lithium ion batteries. The improvement in the electrochemical performance of the graphite electrodes was attributed to the formation of a stable and flexible passive film on their surfaces. It was also revealed that the chemical compositions of the multilayers exerted influence on the electrochemical behavior of the graphite electrodes. The result of this study presents a new strategy to the formation of elastic and strong passive film on the graphite electrode via molecular design. Owing to the diversity of polysilxoane multilayers, this method also enables researchers to control the surface chemistries of carbonaceous materials with flexibility.

  10. Application of a Barrier Filter at a High Purity Synthetic Graphite Plant, CRADA 99-F035, Final Report

    SciTech Connect

    National Energy Technology Laboratory

    2000-08-31

    Superior Graphite Company and the US Department of Energy have entered into a Cooperative Research and Development Agreement (CRADA) to study the application of ceramic barrier filters at its Hopkinsville, Kentucky graphite plant. Superior Graphite Company is a worldwide leader in the application of advanced thermal processing technology to produce high purity graphite and carbons. The objective of the CRADA is to determine the technical and economic feasibility of incorporating the use of high-temperature filters to improve the performance of the offgas treatment system. A conceptual design was developed incorporating the ceramic filters into the offgas treatment system to be used for the development of a capital cost estimate and economic feasibility assessment of this technology for improving particulate removal. This CRADA is a joint effort of Superior Graphite Company, Parsons Infrastructure and Technology Group, and the National Energy Technology Laboratory (NETL) of the US Department of Energy (DOE).